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Contents | Zoom in | Zoom out For navigation instructions please click here Search Issue | Next PageNOVEMBER/DECEMBER 2011SIL EuropeConference highlightsP.21 & P.29LEDsmagazine.comTECHNOLOGY AND APPLICATIONS OF LIGHT EMITTING DIODESStandardsTM-21 and LEDlifetime P.37Edge LightingLearning frombacklights P.61ModulesStandardized andreplaceable LEDs P.43Contents | Zoom in | Zoom out For navigation instructions please click here Search Issue | Next Page

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM | Next PageqqM qMMQmagsTHE WORLD’S NEWSSTAND ®___________________________________________Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM qMM MQmags| Next Page q qTHE WORLD’S NEWSSTAND ®

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM | Next PageqqM qMMQmagsTHE WORLD’S NEWSSTAND ®SpotlightsHong Kong Office:Rm. 223-231, 2/F., East Wing, TST Centre,66 Mody Road, TST East, Kowloon, Hong KongTel: (0755) 3309 3752 / (852) 2723 2302Fax: (852) 2722 1040E-mail: lighting@matrix.hk.comWorldwide Offices: N28650www.viribright.comwww.viribright.com.cn_________________________________Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM qMM MQmags| Next Page q qTHE WORLD’S NEWSSTAND ®

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM | Next PageqqM qMMQmagsTHE WORLD’S NEWSSTAND ®commentaryEuropean focus in aglobal LED industryIn early October, LEDs Magazine held itssecond Strategies in Light Europe conference,which featured a wide range ofpresentations on subjects relating to markettransformation and technology in theLEDs and lighting space (pages 21 and 29).The LED lighting market in Europe is predictedto grow at a CAGR of 41% from 2010 to2015, according to the market-research firmStrategies Unlimited. A key driver will be thegrowth in sales of LED retrofit lamps, drivenby the European directive that has alreadyphased out various types of incandescentlamps at 60W and above. As our article discusses,there are a number of other policyledactions that are promoting the adoptionof solid-state lighting throughout Europe.For example, 2 or 3 major demonstrationprojects are set to be announced shortly,and public procurement will be encouragedto lead by example by making use of energyefficientproducts and services.The European Commission has alsointroduced an EU Quality Charter,which is a voluntary set of criteria thatis intended to promote high-quality LEDlamp products and raise customer awareness.The criteria have been used by EUmember countries to develop their ownquality labels for LED lamps…but ultimatelythis might result in 27 differentlabels! Industry groups, notably the ELC,are calling for a standardized Europe-wideapproach to lamp labelling.Standardization provided a major discussionpoint at Strategies in Light Europe,with particular emphasis on the efforts bythe Zhaga Consortium to provide standardinterfaces for LED light engines (page 43).Three light-engine specifications have beenapproved to date, and Zhaga members arebusy designing products according to thesespecs, although non-members don’t haveaccess to the details. This is perhaps understandable,as Zhaga members want to protecttheir interests and gain a first-moveradvantage. However, this demonstrates asurprising feature of standardization efforts– in most cases, the organizations responsibledo a lousy job of telling industry andother interested parties when new standardsare finalized. TM-21, covering the projectionof long-term lumen maintenance of LEDlight sources (page 37), is a good example.This is hugely important for the LED lightingindustry, but there was little or no fanfarewhen it was finally published after yearsin development. And the IES charges $40 todownload a copy.Strategies in Light Europe also heard fromtwo organizations that are working on aglobal basis; the Global Lighting Forum, andthe IEA Annex on SSL (page 24). Both areexamples of how global cooperation is workingtowards harmonization of standards,and test and measurement protocols, whilealso building a strong consensus withrespect to the benefits of LED lighting.Another organization, the China-basedInternational SSL Alliance, has similar aims.And speaking of China, the recent announcementof a firm schedule for incandescentlamp phase-out (page 17) had a positiveeffect on the share prices of a number of USbasedcompanies with an interest in the LEDmarket, demonstrating again the globaldimension of the LED lighting industry.Tim Whitaker, EDITORtwhitaker@pennwell.comSENIOR VICE PRESIDENT Christine Shaw& PUBLISHING DIRECTOR cshaw@pennwell.comEDITOR Tim Whitakertwhitaker@pennwell.comASSOCIATE EDITOR Nicole Pelletiernicolep@pennwell.comSENIOR TECHNICAL Maury WrightEDITOR maurywright@gmail.comSENIOR TECHNICAL Laura PetersEDITOR laurap@pennwell.comMARKETING MANAGER Luba HrynykPRESENTATION MANAGER Kelli MylchreestPRODUCTION DIRECTOR Mari RodriguezSENIOR ILLUSTRATOR Christopher HippAUDIENCE DEVELOPMENT Jayne Sears-RenferEDITORIAL OFFICES PennWell Corporation,LEDs Magazine98 Spit Brook Road, LL-1Nashua, NH 03062-5737Tel: +1 603 891-0123Fax: +1 603 891-0574www.ledsmagazine.comSALES OFFICESSALES MANAGER Mary Donnelly(US EAST COAST) maryd@pennwell.comTel. +1 603 891 9398SALES MANAGER Allison O’Connor(US WEST COAST) allison@jagmediasales.comTel. +1 480 991 9109SALES MANAGER Joanna Hook(EUROPE) joannah@pennwell.comTel. +44(0)117 946 7262SALES MANAGER Masaki Mori(JAPAN) mori-masaki@ics-inc.co.jpTel: +81 3 3219 3641SALES MANAGER Mark Mak(CHINA & HONG KONG) markm@actintl.com.hkTel: +852 2838 6298SALES MANAGER Diana Wei(TAIWAN) diana@arco.com.twTel: 886-2-2396-5128 ext:270SALES MANAGER Young Baek(KOREA) ymedia@chol.comTel: +82 2 2273 4818CORPORATE OFFICERSCHAIRMAN Frank T. LauingerPRESIDENT AND CEO Robert F. BiolchiniCHIEF FINANCIAL OFFICER Mark C. WilmothTECHNOLOGY GROUPSENIOR VICE PRESIDENT Christine A. Shaw& PUBLISHING DIRECTORSENIOR VP OF AUDIENCE Gloria S. AdamsDEVELOPMENTSUBSCRIPTIONS: For subscription inquiries:Tel: +1 847 559-7330;Fax: +1 847 291-4816;e-mail: led@omeda.com;ledsmagazine.com/subscribeWe make portions of our subscriber list available to carefully screenedcompanies that offer products and services that may be important foryour work. If you do not want to receive those offers and/or informationvia direct mail, please let us know by contacting us at List ServicesLEDs, 98 Spit Brook Road LL-1, Nashua, NH 03062.Copyright © 2011 PennWell Corp (ISSN 2156-633X). All rightsreserved. Contents of this publication may not be reproduced in anyform without prior written consent of Publishers.4 NOVEMBER/DECEMBER 2011 LEDsmagazine.comPrevious Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM qMM MQmags| Next Page q qTHE WORLD’S NEWSSTAND ®

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM | Next PageqqM qMMQmagsTHE WORLD’S NEWSSTAND ®GELightingFrom a Tiny Twist Grows a Full Revolution.The GE Infusion LED Module is more than flexible, it’s built for the future. As LED technology advances, you can twist in newergenerations of the Infusion module without replacing fixtures. And with a full line of lumen packages up to 3500, multiple colortemperatures, and CRI and dimming options, the energy efficient LED module paves the way for a revolution in lighting design.Explore the GE Infusion LED Module, luminaire options and a variety of applications online at www.gelighting.com/infusion© 2011 GEPrevious Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM qMM MQmags| Next Page q qTHE WORLD’S NEWSSTAND ®

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM | Next PageqqM qMMQmagsTHE WORLD’S NEWSSTAND ®Webcasts:LED Lighting Made Easy – A Modular SystemApproach to Designing FixturesDATE: October 2011PRESENTERS: Costa Politakis, FutureLighting SolutionsDan Sullivan, Philips LightingLight and Color - Methods of AchievingHigh CRI with LEDsDATE: October 2011PRESENTER: Marc Dyble, Osram Opto SemiconductorsEfficient Driving and Safe Monitoringof Multiple LED ArraysDATE: October 2011Creating Highly Efficient, Highly ReliableLighting Designs with Multiple LED StringsDATE: November 2011PRESENTER: Alexander Craig,Fairchild SemiconductorAn LED Luminaire Solution ForIndoor Area LightingDATE: November 2011PRESENTER: Valentin Kulilov, ON SemiconductorDiagnosing and Solving Thermal Challengesin Next-Generation LEDsDATE: November 2011PRESENTER: Boris Marovic, Mentor GraphicsVisit www.ledsmagazine.com/webcaststo access upcoming and archived presentations.FEATURED article| onlineChinese LED manufacturing – more than just LEDsSignificant investments and subsidies have enhanced Chinese companies’capabilities to produce not only LED chips and packaged devices, but also materialsand equipment used in LED manufacturing, as TOM HAUSKEN explains.www.ledsmagazine.com/features/8/11/1ADVERTISERS indexBeautiful Light Tech ............................27Cree, Inc. ................................... 23, C4CSA International ...............................25EBV Elektronik .............................. 40-41Evergreen International Corp. ............. 50Fin-Core Corp. ....................................31Fusion Optix ...................................... 48Future Electronics, Inc. ...................... 64GE Lighting Solutions ............................5Global Lighting Technologies .............. 63Helio Optoelectronics Corp. ................52Instrument Systems GmbH .................70Inventronics (Hangzhou) Co., Ltd. ....... 60Lambda Research Corp. .................... 12Ledlink Optics Inc. ..............................19Linear Technology .............................. C3Lutron Electrics Co, Inc. ..................... C2Matrix Lighting Limited, Hong Kong .......1MeanWell USA ....................................16National Semiconductor..................... 45Nordson Asymtek .............................. 33Optotune AG .......................................67Optronic Laboratories .........................59Orb Optronix ...................................... 34Phihong USA ..................................... 20Philips Lighting BV ............. 9, 11, 13, 15Philips Lumileds ...................................2Farnell Danmark AS ............................42Proto Labs, Inc. ................................. 53Recom Distribution &Logistics Gmbh ..................................28Samsung LED America ...................... 35Seoul Semiconductor Co Ltd. ................7Shanxi Guangyu LedLighting Co Ltd. ..................................14Shenzhen RefondOptoelectronics Co., Ltd. ................... 46Sichuan Jiuzhou ElectricGroup Co Ltd. .................................... 49Signcomplex Ltd. ................................73Specialty Coating Systems..................47Stellarnet, Inc. ................................... 39Supertex Inc. ......................................77Thomas Research Products ............... 56Underwriters Laboratories ................. 36VS Optoelectronic GmbH & Co KG ...... 266 NOVEMBER/DECEMBER 2011 LEDsmagazine.comPrevious Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM qMM MQmags| Next Page q qTHE WORLD’S NEWSSTAND ®

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM | Next PageqqM qMMQmagsTHE WORLD’S NEWSSTAND ®Fortimo LED Modulesfor today, for tomorrowNew!Fortimo LED SLM gen 2Future-proof, high quality andprogressive LED technology for retail.Designed to give you the best quality of white lightand easy design-in, now and in the future. Many leadingmanufacturers already use Fortimo as the trusted lightsource in their luminaires. See why at philips.com/fortimoPrevious Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM qMM MQmags| Next Page q qTHE WORLD’S NEWSSTAND ®

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM | Next PageqqM qMMQmagsTHE WORLD’S NEWSSTAND ®Fortimo LED Modulesfor today, for tomorrowFuture-proof, high quality andprogressive LED technology for hospitality.Designed to give you flexible warm white light, now andin the future. Many leading manufacturers already useFortimo as the trusted light source in their luminaires.See why at philips.com/fortimoPrevious Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM qMM MQmags| Next Page q qTHE WORLD’S NEWSSTAND ®

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM | Next PageqqM qMMQmagsTHE WORLD’S NEWSSTAND ®news+viewsHowever, Veeco’s third-quarter bookingswere $133 million, a decline of 57% sequentially.LED & Solar orders declined 59%sequentially to $112 million, with MOCVDorders at $103 million. “Veeco’s third-quarterorders were impacted by weak near-termLED industry demand, low MOCVD equipmentutilization rates in Asia, and decreasedbusiness activity in China,” commented JohnPeeler, Veeco’s CEO.Aixtron’s equipment order intake was alsodown sequentially by 77% to EUR 51.5 million($71 million) in Q3 of 2011, relative toEUR 222.2 million ($306.0 million) in Q2.Equipment order intake in the first 9 monthsof 2011 was down 11% year-over-year at EUR484.1 million ($666.8 million).Aixtron’s quarterly revenues decreasedby nearly half (49%) from EUR 175.6 million($241.9 million) in Q2 to EUR89.8 million($123.7 million) in Q3 2011. Revenues inthe first 9 months of 2011 decreased 16% toEUR 470.8 million ($648.4 million) from EUR558.1 million ($768.7 million) in the sameperiod last year. The cause was customerdelays in delivery dates and credit tighteningin Asia, said the company.Paul Hyland, president and CEO of Aixtron,described current market conditions as“difficult” but said: “There can be no doubt inanybody’s mind that the LED lighting investmentcycle will come and will be the biggestend-market opportunity this industry hasever seen. It is not a question of ‘if’ it is onlya question of ‘when’.” ◀MORE: www.ledsmagazine.com/news/8/11/3OUTDOORWelland switches to LEDsThe City Council in Welland, Ontario,Canada, has voted unanimously to completelyreplace the city’s street lights withLED fixtures. The Council approved anagreement with SSL Energy Solutions andAppalachian Lighting Systems Inc. (ALSI)to replace the existing street-lighting systemthroughout the city with ALSI’s ALLEDfixtures and ALLink control system.The capital cost of CAN$2.74 million willbe financed through a debenture, and paidback by utilizing the energy savings fromthe program. In year one, street-lightingenergy costs should be reduced by $221,553with a saving in maintenance costs of$159,250. Phase 1 of the project will includethe replacement of 4300 cobrahead HPSfixtures by April 2012. Phase 2 will consistof replacement of 2410 decorative fixtures,scheduled for completion in December2012.Welland estimates that the total cost ofoperating its current HPS-based lightingsystem would amount to almost $18 millionover 15 years, which is the “estimatedtrue cost of doing nothing.” By switching toLED lighting, the City will save $6.8 millionin operating costs. After paying the variouscharges including debt repayments, thecity will save $2.38 million in total over the15-year term of the agreement. ◀MORE: www.ledsmagazine.com/news/8/9/31Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM qMM MQmags| Next Page q qTHE WORLD’S NEWSSTAND ®

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM | Next PageqqM qMMQmagsTHE WORLD’S NEWSSTAND ®Fortimo LED Modulesfor today, for tomorrowFuture-proof, high quality andprogressive LED technology for outdoor.Designed to give you the best LED performancewith high quality of white light, now and in thefuture. Many leading manufacturers alreadyuse Fortimo as the trusted light source in theirluminaires. See why at philips.com/fortimoPrevious Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM qMM MQmags| Next Page q qTHE WORLD’S NEWSSTAND ®

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM | Next PageqqM qMMQmagsTHE WORLD’S NEWSSTAND ®news+viewsLED FABRICATIONOptogan opens LED chip fabOptogan GmbH has held an opening ceremonyfor its LED chip-production facilityin the German city of Landshut. The sitepreviously housed a Hitachi semiconductorfactory, with a clean-roomarea of 4000 m². Optoganhas invested tens of millionsof euros in the site,which will employ up to100 people. Initial capacitywill be over one billionLED chips per year.According to Optogan,the facility is Europe’s second-largestLED chip-productionsite. The largestis also in Germany, namely Osram OptoSemiconductors’ plant in Regensburg. TheOptogan Group, headquartered in Russia,opened a large LED packaging facility in St.Petersburg last year (www.ledsmagazine.com/news/7/11/29).“In Landshut, we have discovered theideal infrastructure for our future highvolumeproduction of LED chips,” saidHans Peter Ehweiner, managing director ofOptogan GmbH. “Our LED lamps and luminairesare on the way towards lighting upindoor, outdoor, and residential areas allover the world.” ◀MORE: www.ledsmagazine.com/news/8/10/14LED MATERIALSRubicon ships 200,000th6-inch waferRubicon Technology, Inc. (Nasdaq:RBCN) hasstated that it has shipped over 200,000 six-inchsapphire wafers to LED manufacturers worldwide.Rubicon had previously announced thatit had upgraded the crystal-growth furnacesin its three manufacturing facilities to allow8-inch sapphire wafer production. Rubiconhas production facilities in Bensenville, IL,Batavia, IL and Penang, Malaysia.Also, Rubicon says it has begun productionof aluminum oxide, the startingmaterial used to manufacture sapphire.On-site processing of aluminumoxide will allow better process controland the growth of higher-quality sapphirewith larger crystals. Some analystsexpect 8-in wafers to account for morethan 50% of the LED market by 2016.MORE: www.ledsmagazine.com/news/8/10/32_____________ _________Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM qMM MQmags| Next Page q qTHE WORLD’S NEWSSTAND ®

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM | Next PageqqM qMMQmagsTHE WORLD’S NEWSSTAND ®Fortimo LED Modulesfor today, for tomorrowFuture-proof, high quality andprogressive LED technology for offices.Designed to give you the highest energy efficiency andcomfortable white light, now and in the future. Many leadingmanufacturers already use Fortimo as the trusted lightsource in their luminaires. See why at philips.com/fortimoPrevious Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM qMM MQmags| Next Page q qTHE WORLD’S NEWSSTAND ®

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM | Next PageqqM qMMQmagsTHE WORLD’S NEWSSTAND ®__________________Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM qMM MQmags| Next Page q qTHE WORLD’S NEWSSTAND ®

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM | Next PageqqM qMMQmagsTHE WORLD’S NEWSSTAND ®fundingprogramsEPA releases first draft ofEnergy Star Lamps specThe US Environmental Protection Agency(EPA) has published the first draft of theEnergy Star Lamps v1.0 specification atwww.energystar.gov/lamps. This is intendedto replace the existing Compact FluorescentLamps and Integral LED Lamps specifications.Comments or concerns about this firstdraft should be sent to lamps@energystar.govby December 9.The specification is described by the EPAas “technology-neutral” and includes a proposalto align lamp-life requirements acrosstechnologies by introducing a 10,000-hr minimumlifetime requirement (for LED lamps,this would be a 10,000-hr rated lumen maintenancelife).The specification is limited to lampsintended to be connected to the electricpower grid. It includes photometric performancerequirements, lumen maintenance andreliability requirements, luminous-intensitydistribution requirements, electrical performancerequirements, dimensional requirements,and lamp labeling and packagingrequirements for all lamp types included inthe specification.In December 2009, the EPA laid out a plan tointegrate the four existing Energy Star lightingspecifications into two, new, technologyneutralspecifications: Luminaires (light fixtures- www.ledsmagazine.com/news/8/5/23)and Lamps (light bulbs). EPA says that its goalwas “to better serve the consumer interest inidentifying energy-saving lighting products byensuring that performance requirements andtesting methods reward efficiency and quality,irrespective of technology.” In doing so, theEPA is also seeking to remove any overlap orcontradiction among specifications.For lamps, the EPA initiated a consultationprocess in March 2011, feedback from whichcan be viewed on the Lamps website (www. ____energystar.gov/lamps). This feedback focusedthe EPA’s attention on further improvementsto quality-related requirements rather thanincreases to the already-high efficiencyrequirements.The EPA has addressed consumer barriersto adoption by developing proposed improvementsto lamp start time, run-up time, colorconsistency, and reliability in high-heat andfrequent-switching applications. The EPA alsore-evaluated the lamp labeling and packagingrequirements in the existing specifications.The first draft also includes a proposal toalign lamp-life requirements across technologies,creating an “even playing field.” Specifically,the draft includes a proposal for a10,000-hr minimum lifetime requirement.The EPA says that product data shows thisrequirement to be readily attainable withCFLs. While the Integral LED Lamps specificationhas required a 15,000- to 25,000-hrminimum, “there are disadvantages to thisapproach which appear to be hindering adoptionof LED lamps,” said the EPA.Several lamps are excluded from the specificationincluding lamps that operate on anexternal ballast, driver or transformer; lampspowered by an internal power source, e.g.solar; lamps with other power-consuming featuresthat do not provide useful illumination;lamp technologies without industry-standardizedmethods of measurement; lampswith bases not detailed in ANSI standards;and Zhaga-defined LED modules. ◀China unveils plansfor incandescentlamp phase-outChina has unveiled its three-step planfor phasing out energy-inefficient incandescentlamps. The announcement onNov 4 caused a surge in the share price ofseveral LED companies, including Cree.According to the Xinhua News Agency,the phase-out will ban imports and salesof incandescent lamps in the followingcategories, as follows:• 100W and above: October 1, 2012• 60W and above: October 1, 2014• 15W and above: October 1, 2016Xie Ji, deputy director of the environmentalprotection department with China’sNational Development and ReformCommission (NDRC), said that the planshows China’s determination to pressahead in its efforts to save energy, reduceemissions and curb climate change.China is a major manufacturer andconsumer of lighting products and is theworld’s largest producer of both energysavinglamps (CFLs) and incandescentbulbs. In 2010, incandescent-lamp productiontotaled 3.85 billion units, anddomestic sales stood at 1.07 billion units,said Ji.Power consumption for lighting inChina accounted for 12% percent of thecountry’s total electricity use in 2010.The NRDC expects that the plan willenable China to save 48 billion kWh ofpower per year and reduce CO2 emissionsby 48 million tonnes annually.China’s phase-out ties in with legislationin other countries and regionsto stop using these products. Europe’sincandescent phase-out affected60W-and-higher lamps from September2011 (www.ledsmagazine.com/________news/8/9/1), while the US begins itsnationwide ban on 100W-and-aboveincandescent lamps from January 1,2012. ◀MORE: www.ledsmagazine.com/news/8/11/7 _______LEDsmagazine.com NOVEMBER/DECEMBER 2011 17Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM qMM MQmags| Next Page q qTHE WORLD’S NEWSSTAND ®

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM | Next PageqqM qMMQmagsTHE WORLD’S NEWSSTAND ®fundingprogramsLUMEN coalition launches websiteThe LUMEN (Lighting Understanding for a More Efficient Nation)coalition has launched a website (www.lumennow.org) dedicatedto informing US consumers regarding energy-efficient residentiallighting options. The coalition is led by the Alliance to SaveEnergy, the American Lighting Association (ALA) and the NationalElectrical Manufacturers Association (NEMA) and includes participantsfrom more than 40 nonprofit energy-efficiency advocacygroups, utilities, lighting manufacturers and trade associations.The coalition has estimated an annual energy saving per householdof up to $100 by replacing less-efficient bulbs with halogen,CFL or LED options. “Understanding which option is best for aspecific application is where LUMEN members can help the homeowner,”said Larry Lauck of the ALA.The website includes a guide to selecting replacement bulbs,frequently-asked questions, and news regarding energy-efficientlighting options. The website also explains the new FTC LightingFacts label, which will be required on all medium screw-basebulbs sold in the US as of January 1, 2012. ◀MORE: www.ledsmagazine.com/news/8/10/23The city of Stamford, CT, has installed over 1000 cobraheadLED fi xtures from GE, leading to an annual saving in energycosts of $146,000. Initially, LED street lights did not farewell in comparison with other products, but the newer GEproducts offered improvements in terms of a color temperatureof 4300K, better uniformity and reduced glare (www. ___ledsmagazine.com/news/8/10/33).DOE consortium publishes LEDstreet-lighting guidelinesThe DOE Municipal Solid-State Street Lighting Consortium hasposted specification templates for use by utilities and municipalitiesthat are evaluating or implementing LED street-lighting projects.The first draft of the Model Specification was posted in Apriland the revised specification takes into account feedback fromconsortium members and the wider community.The Model Specification contains two guidelines and is availableat www.ssl.energy.gov/specification.html. _________________________ The System Specificationoption for municipalities (Appendix A), is designed tomaximize application efficiency and incorporates site characteristicssuch as pole spacing and mounting height. Meanwhile, theMaterial Specification option for utilities (Appendix B), emphasizesluminaire efficiency and does not consider site characteristics.The flexible format of the guideline allows users to modifydefault values to fit their local design criteria, which typicallyvary from city to city, and even from application to applicationwithin a given city. ◀MORE: www.ledsmagazine.com/news/8/10/29_________________________Competition begins for NextGeneration LuminairesThe US DOE has announced that its Next Generation Luminaires(NGL) SSL competition has been separated into two competitions,for indoor and outdoor products, due to growth in participation.Each competition will have its own judging panel, and the datesare now staggered. The intent-to-submit deadline for indoor NGLsis December 16, while final online submissions are due by January13, 2012. Physical product samples are due by January 18, andwinners will be announced in May. The DOE will send out its callfor entries for the outdoor NGL competition in March 2012, withawards being presented in August 2012.The competition is jointly sponsored by the DOE, the IlluminationEngineering Society of North America (IESNA), and the InternationalAssociation of Lighting Designers (IALD). In the NGL SSLcompetition, the judges examine lighted samples in their intendedapplications, as well as photometric data and other documentation.Evaluation criteria include the quality and quantity of illumination,energy efficiency, and serviceability. ◀MORE: www.ledsmagazine.com/news/8/2/27DOE releases promising resultsfrom Round 13 Caliper testingThe US Department of Energy (DOE) has completed Round 13of product testing through its SSL Caliper program. Round 13included three types of products: LED and benchmark high-bayluminaires, LED wallpack luminaires, and LED and benchmark2x2-foot troffers. The summary report provides an overview ofphotometric performance results, compares the results withrespect to similar products that use conventional light sources,and can be downloaded at www.ssl.energy.gov/reports.html.On average, the round 13 LED luminaires showed a significantimprovement in efficacy over LED luminaires tested in 2009 and 2010,with a minimum efficacy close to the average observed in 2009-2010.In addition, the variation in performance across the Round 13 LEDluminaires was less than in 2009-2010 products; that is, there weresmaller differences between minimum and maximum efficacy. A similartrend was observed with other performance parameters includinginitial lumen output, CCT and CRI.MORE: www.ledsmagazine.com/news/8/10/1618 NOVEMBER/DECEMBER 2011 LEDsmagazine.comPrevious Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM qMM MQmags| Next Page q qTHE WORLD’S NEWSSTAND ®

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM | Next PageqqM qMMQmagsTHE WORLD’S NEWSSTAND ®_______________________Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM qMM MQmags| Next Page q qTHE WORLD’S NEWSSTAND ®

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM | Next PageqqM qMMQmagsTHE WORLD’S NEWSSTAND ®Think Phihongenergy efficient LED drivers...or it’s lights out.Shouldn’t your LED driver last as long as your LEDs?Why spec LEDs with 40 – 50,000 hour life if your LED driver doesn’t make it past 5K?Built on a tradition of high quality, high efficiency power products, Phihong’s high quality LEDdrivers support multiple strings with independent current control, a wide range of applications(3-200W) and feature dimming, IP67 rating for outdoor environments and UL and FCC certification.Phihong ships millions of OEM products every month with millions of hours DMTBF.Make sure your next LED product design keeps operating. Phihong LED drivers won’tleave you standing in the dark.New LED driversfrom PhihongFor complete technical information visitwww.phihong.com/LED or call 1.888.PHIHONG (744.4664)Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM qMM MQmags| Next Page q qTHE WORLD’S NEWSSTAND ®

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM | Next PageqqM qMMQmagsTHE WORLD’S NEWSSTAND ®conferences | STRATEGIES IN LIGHT EUROPEStrategies in Light Europe focuses onLED lighting and market transformationEurope-wide policies related to solid-state lighting, as well as standardization, lighting quality,product labels and global initiatives, were among the many subjects tackled at Strategies in LightEurope 2011. TIM WHITAKER reports.With more than 900 registeredparticipants, the second annualStrategies in Light Europe 2011conference and exhibition took place inMilan, Italy, on October 4-6, 2011. Onenew feature of this year’s event was theintroduction of parallel tracks on MarketTransformation and Technology: the latteris covered in a separate article on page 29.The LED lighting market in Europe isexpected to grow at a compound annualgrowth rate of 41% between 2010 and 2015,according to the Keynote presentation byVrinda Bhandarkar, Strategies Unlimited’sDirector of LED Lighting Research (Fig. 1).The replacement-lamps sector will growmost rapidly, as the impact is felt of Europewidelegislation to remove inefficient lampsfrom the market.Bhandarkar said that the global LEDlighting market had revenues of $5 billionin 2010, of which 21% was from replacementlamps and the remainder from luminaires.In general, performance is improving andprices are falling, but there are “huge issueswith low-quality, under-performing LEDproducts,” said Bhandarkar. She also saidthat standards setting is moving rapidly, butneeds consistency between regions. Productquality, labeling, and standardizationwere all themes taken up by other speakersat the conference. Module standards, forexample, were discussed by Andy Davies ofGE Lighting (see www.ledsmagazine.com/________news/8/10/10 and page 43 of this issue).Also in the Keynote session, DominikWee and Arthur Jaunich from McKinsey &Company covered the main points of theirrecent report entitled “Lighting the way:Perspectives on LEDs and the global lightingmarket” (www.ledsmagazine.com/features/8/9/13)._________A different perspective was provided bySimon Fisher, general manager EMEA forIndoor Luminaire Solutions with GE Lighting.Fisher, formerly an independent lightingdesigner, gave a talk entitled “Designingwith LEDs: Redefiningthe Lit Environment”but he was ($ Billion)Revenuekeen to stress that 7LEDs are not the6only game in town.“This is the Strategiesin Light con-5ference,” he said. 4“It’s important to3develop LED solutionsbut not ignore 2other technologies…1this is GE’s strategygoing forward.” 0Fisher advocateda holistic approachto product design,encompassing notonly the components and application design,but also system integration and quality andreliability. “We need to have a solution-orientatedapproach to customer needs,” he said.Focusing on modules, Fisher said that connectivityis the “design key.” While electricalcompatibility reduces losses, good thermalcontact sustains the LED lifetime and astrong mechanical connection maintains systemintegrity.From a client perspective, good opticalquality is key, said Fisher. Clients requirea choice of beam angles, high light-outputratio (LOR), and repeatable performance.He then discussed GE optics that are compatiblewith the company’s module products,and also revealed that GE will introducemodule-based luminaires for indooruse in Q3 2012.Fisher said that the lighting industryhas changed recently: “Five or six yearsago the discussion was mainly on capitalLED lighting market in EuropeCAGR 41%2010 2011 2012 2013 2014 2015ReplacementlampsLuminairesSource:Strategies UnlimitedFIG. 1. Market forecast for LED lighting product sales in Europe.cost, now return-on-investment is part ofthe discussion,” he said. “This is important,because we’re going to be asking people tospend more on their lighting than they doat present.”European SSL policies and actionsEU policies for the promotion of SSL werediscussed in detail by Paolo Bertoldi of theEuropean Commission (EC) Joint ResearchCentre (http://re.jrc.ec.europa.eu/energyefficiency).____ Energy efficiency, including lighting,is a key component for reaching Europe’s variousclimate and energy objectives by 2020.“Lighting is covered by many policies andactions, including the new strategy for SSLLEDsmagazine.com NOVEMBER/DECEMBER 2011 21Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM qMM MQmags| Next Page q qTHE WORLD’S NEWSSTAND ®

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM | Next PageqqM qMMQmagsTHE WORLD’S NEWSSTAND ®conferences | STRATEGIES IN LIGHT EUROPEunder the Digital Agenda for Europe,” saidBertoldi. Among the activities are energylabeling, public procurement, the Eco-Designdirective, and R&D programs in the currentFP7 and future FP8 programs. The generalaim is to support the most efficient technologies,and to introduce financial schemes thatcan overcome the barrier of high initial cost,a particular problem for SSL.For many years, Europe has used theenergy label, which grades appliances(including lamps) from A to G according toenergy usage. This is now under review andis due to be revised by May 2012. Also, by settingminimum energy-efficiency requirements,the Eco-Design Directive has alreadyhad a major impact on the lamp market inEurope: 60W incandescent lamps were effectivelyoutlawed from September 2011 (www. ____ledsmagazine.com/news/8/9/1). As Bertoldiexplained, the second phase of the Directive,covering directional lamps, is due tobe adopted by July 2012.Lighting is also part of the Energy Performancefor Building Directive, which is aimingto move towards “almost zero-energybuildings.” However, feeling the need for anew impetus, the EC has put forward a proposalfor a new Energy-Efficiency Directive(EED). One aspect would be to call on thepublic sector to lead by example, by purchasingproducts, servicesand buildings thathave high energy-efficiencystandards. Also,national energy-efficiencyschemes couldencourage utilities todistribute LED lamps toconsumers, which Bertoldidescribed as a “greatopportunity” for LEDs.SSL is a central partof the Digital Agenda forEurope, which focuses onways that informationand communicationstechnology (ICT) canstimulate the EU economyand benefit society.Specific SSL-relatedactions include a GreenPaper, to be published later this year, and thelarge-scale SSL demonstration projects thatshould start at the beginning of 2012 (www.___________FIG. 2. Module-based luminaires on the GE Lighting stand at SIL Europe.FIG. 3. Dekra’s certifi cation markfor LED products.___ledsmagazine.com/news/8/2/5).In R&D, the EC is currently funding variousprograms in LEDs and OLEDs to thetune of around EUR 90 million, said Bertoldi.He also gave a number of project examplesfrom the GreenLight program (www. ____eu-greenlight.org), an EC-lead voluntary initiativeto reduce lightingenergy use in commercialand industrial sectorsand in street lighting.Standards andCELMA guidelinesStandardization was acentral discussion topicat SIL Europe, and wascovered in detail by KayRauwerdink of CELMA,an organization that representsthe Europeanlighting industry for luminairesand components.CELMA has written aguidance paper on qualitycriteria for LED luminaireperformance thatfocuses on two PublicAvailable Specifications (PAS) documents thatwere recently published by IEC, the internationalstandards body. IEC/PAS 62717 coversperformance requirements for LED modules,while IEC/PAS 62722 covers LED luminaires,in both cases for general lighting.Rauwerdink said the industry needs totransition from “comparing apples andpears” when it comes to commercial products,and instead make apples-to-applescomparisons. “Evaluating performanceclaims from different manufacturers cannotbe done without using a standardizedset of quality criteria that are measured incompliance with appropriate standards,” hesaid. The CELMA guide suggests that usersof LED luminaires should request LED luminairespecifications that are measured incompliance with the new IEC documents.The documents were released simultaneouslyto ensure consistency between module-and luminaire-quality criteria. Thesecriteria include a large selection of metrics,including input power, luminous flux andefficacy; luminous intensity distribution;CRI and chromaticity coordinate values,both initial and maintained; rated life (inhours) and associated rated lumen maintenance(in lux); and failure fraction (Fy), correspondingto the rated life of the LED modulein the luminaire.The CELMA guide explains the best methodsfor measuring these criteria, and why22 NOVEMBER/DECEMBER 2011 LEDsmagazine.comPrevious Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM qMM MQmags| Next Page q qTHE WORLD’S NEWSSTAND ®

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM | Next PageqqM qMMQmagsTHE WORLD’S NEWSSTAND ®®LIGHTING-CLASS LEDsXLAMP ML-B & ML-E LEDsOPTIMIZED FORSMOOTH-LOOK LIGHTINGLonger lifetime than backlighting LEDs(and the LM-80 data to prove it)Best color consistency with industry’ssmallest color binsXLAMP XP-E HEW LEDsOPTIMIZED FORNON-DIRECTIONAL LIGHTINGLowers the cost of high-efficiencyLED systemsLight optimized for your application—many CCT & CRI options availableXLAMP CXA2011 LEDsOPTIMIZED FORNON-DIRECTIONAL LIGHTINGSimple assembly—no solderingor connectors requiredWide lumen output range—upto 3500 lumensat 45W, 85°CCREE XLAMP LEDs ARE APPLICATIONOPTIMIZED FOR LOWEST SYSTEM COSTREVOLUTIONARY!Cree XLamp ® Lighting-Class LEDs arepurposefully designed to deliver theindustry’s best performance and optimizedspecifically for distinct applications.Our revolutionary product portfolio enablesyou to design brighter, more efficientluminaires with fewer LEDs or simply useless LEDs and save space. So whetheryou’re designing the next generation ofindoor downlights or lights that emulatethe look of fluorescent tubes, you canlower your system cost.Get samples of Cree XLamp LEDs orcontact a Cree Solutions Provider atcree.com or call us at 800.533.2583Get Cree reference designsfor non-directional applicationsat cree.com/refPrevious Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM qMM MQmags| Next Page q qTHE WORLD’S NEWSSTAND ®

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM | Next PageqqM qMMQmagsTHE WORLD’S NEWSSTAND ®conferences | STRATEGIES IN LIGHT EUROPEthey are important. The document furtherexplains the difference between lifetimeclaims based on lumen maintenance andluminaire lifetime claims that depend oncomponent reliability.LED Quality CharterWith the advent of the Eco-Design Directiveto remove inefficient lamps from theEuropean market, it was also deemed necessaryto establish an EU LED QualityCharter (EU-QC), which was discussed atSIL Europe by Casper Kofod of Energy Piano.The EU-QC is a voluntary set of criteria thatis intended to promote high-quality LEDbasedlamps, to raise consumer awarenessand confidence, and to support promotionand procurement campaigns. Organizationscan sign up to support the EU-QC, which isrestricted only to LED lamps (not modules orluminaires), and to the residential, not commercial,sector.Importantly, the EU-QC is not a qualitylabel, although individual EU member countriescan use the EU-QC to develop their ownenergy-efficiency labels, such as those introducedin the UK or in Kofod’s home countryof Denmark. The recommended criteria canby viewed by downloading the EU-QC documentfrom the Residential Lighting sectionof the JRC website (http://re.jrc.ec.europa._____________eu/energyefficiency/).Surprisingly, considering levels set byother similar programs, the EU-QC requirementfor power factor (PF) is a minimum of0.5. Kofod said that “the consumer has noadvantages of high PF requirement, but disadvantagesif an extra corrector-circuit isinstalled.” The disadvantages come in termsof additional size, consumption, cost andother factors. He also said that lighting iscurrently 15-17% of domestic consumption,but in the future, when LEDs predominate, itwill be only 2-4%. In this case, a high PF willonly provide a marginal advantage: “We’retalking about peanuts,” said Kofod.The Danish Energy Savings Trust (EST)has developed a quality label for lampsthat meet EU regulations and the requirementsof the EU-QC, explained Kofod. Thelamps are self-certified, but the EST mayperform random testing. Demark is at theforefront of green policy development, andrecently announced that renewable energysources would be required to cover all electricityand heat consumption by 2035, andall energy consumption by 2050. “There is agreat future for LEDs to help slash energyconsumption in Denmark,” said Kofod.However, not everyone agrees that EUmember states should use the EU-QC todevelop their own labels: one obvious potentialconsequence could be 27 different labelingschemes, one for each country. AfterKofod’s talk, Jürgen Sturm of the EuropeanLamp Companies Federation (ELC) saidthat the European lighting industry “favorsa Europe-wide approach, not fragmentationof labels on a country-wide basis.”Dekra performance markIn his presentation, Jacob Neusink ofDekra, a quality and safety service-provider,asked: “Is there a need for an LEDquality mark?” Not surprisingly, Neusink’sanswer was yes, giventhat Dekra has alreadyissued its own LED performancemark (Fig. 3) totwo Netherlands-basedmanufacturers, LemnisLighting and Ledned.In explaining why themark was introduced,Neusink quoted commentsfrom Dekra’s customers.He said thatinstallers ask: “How canI be sure that the claimsmy supplier makes aretrue and how do I knowthat the products I buywill perform?” Meanwhile,manufacturerssay: “I have a high-qualityproduct with good performance,and my customerdoes not believewhat I am saying.” Toaddress such comments,the Dekra mark sets performancelevels for LEDlamps, or modules, orluminaires.Neusink pointed outthat this is a “qualitymark,” where testingconfirms that the performancereaches or exceeds the requiredlevels set by Dekra, rather than a “truthmark,” which simply confirms that the figuresquoted by the manufacturer are accurate.It’s important to note that Dekra offersits mark on a commercial basis, as distinctfrom government-sponsored programssuch as the Danish EST label mentionedabove (www.dekra-certification.com/en/led-performance-mark).______________Global initiativesThe challenge of harmonizing SSL-relatedactivities on a global basis has been taken upby at least two new organizations. The mainaims of the International Energy Agency(IEA) Annex on SSL (http://ssl.iea-4e.org), asdescribed at SIL Europe by Marc Fontoynont(Fig. 4), are to develop SSL quality assurance,to harmonize SSL performance testing,and to promote standards and developFIG. 4. Marc Fontoynont of Aalborg University discussed theIEA Annex on SSL, which aims to increase confi dence in SSL,and to allow governments to prepare more ambitious policiesfor energy-effi cient lighting products, for example relating toregulation and labels.24 NOVEMBER/DECEMBER 2011 LEDsmagazine.comPrevious Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM qMM MQmags| Next Page q qTHE WORLD’S NEWSSTAND ®

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM | Next PageqqM qMMQmagsTHE WORLD’S NEWSSTAND ® ® Third-party certifi cation and verifi cation are nowENERGY STAR requirements. CSA International hasENERGY STAR TestingFacility and Certifi cation Body. That means today wecan meet all of your lighting product safety and energyeffi ciency testing needs with a single, seamlesslyeffi cient testing program that saves you timeand money.Look to CSA International to meet ENERGY STARrequirements for lighting products including:If you prefer to perform testing using your own testinglaboratory, we can qualify your lab facilities under ourTesting Laboratory program, then verify your test resultsContact us today and learn how much time andmoney a combined safety and energy efficiencytesting program with CSA International can save you.1-866-463-1785 cert.sales@csa-international.orgwww.csa-international.orgPrevious Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM qMM MQmags| Next Page q qTHE WORLD’S NEWSSTAND ®

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM | Next PageqqM qMMQmagsTHE WORLD’S NEWSSTAND ®conferences | STRATEGIES IN LIGHT EUROPE____________an accreditation infrastructure.Meanwhile, the lighting industry is representedby the Global Lighting Forum (GLF),a gathering of lighting organizations fromaround the world representing over 5,000lighting manufacturers and US$50 billionin annual sales. Jürgen Sturm, GLF generalsecretary, explained that the GLF aims toshare knowledge of global lighting trendsand legislative developments. It acts as anetworking forum, developing joint industrypositions and communicating these togovernment authorities and other stakeholders.One of its specific priorities is to “acceleratethe uptake of LED and OLED lightingsolutions,” he said.The benefits of SSL can be defined, saidSturm, in seven dimensions: energy, system,environmental, biological, business, designand quality. “The benefits over all otherlighting technologies are unique, as only SSLcombines all [these] dimensions,” he said. Inthe biological dimension, Sturm said that“biological effective lighting” can influenceour well-being and health, and that LEDtechnology can help to manage the effects ofdemographic change, particularly for agingpopulations. However, he described the biologicaldimension as a “research topic” thatoften “raises a lot of tension.”In terms of business, Sturm said that “thecharacteristics and benefits of LED-lightingtechnology will lead to a change in businessmodels in lighting.” Models based on recurringrevenues from replacement sales (i.e.lamps) will be superseded by models basedon revenues over life including energy savings,but these will require innovative financingmodels. Sturm also said that LED lampsales will peak in 2018 due to the growth insales of integrated lamps and systems.LED market in RussiaEvgeny Dolin, chairman of the Russiannational association for manufacturersof LEDs and LED-based systems (www. ____nprpss.ru), ______ said that the Russian LED marketexperienced very rapid growth of 50-60%in 2010. Even so, LED lighting fixtures wereonly about 5% of the total lighting market in2010, with revenues of US $67 million. Thesefigures are expected to increase to 15% and$333 million by 2015.Dolin said that the Russian government issupporting energy efficiency and promotingthe use of LEDs, while the biggest corporationsare starting investment programs forLED lighting. One example is Russian Railways,which invested EUR 13 million in 2010,and EUR 24 million in 2011. Russia is tryingto derive maximum benefit by switchingdirectly from incandescent lamps to LEDlamps, skipping the move to compact-fluorescentlamps (CFLs) that has been prevalentelsewhere in Europe.Dolin’s organization is of course involved instandards work, and he said that Russia hasadopted the LED color-coordinates specifiedin the ANSI C78.377 standard. Also, October2011 saw a national requirement come intoplay for a minimum efficacy of 50 lm/W forLED lighting. In the case of retrofit lamps, theminimum is between 50 lm/W and 70 lm/Wdepending on color temperature.Dolin said that the organization is workingto harmonize Russian measurement laboratorieswith international efforts. He pointedout that it is difficult for Russia to use USdevelopedstandards without modifications,due to differences such as climate, and thenature of the electrical grid.Business developmentOne member of the Russian LED manufacturers’association is Optogan, which has amajor production facility in St. Petersburgand also recently opened an LED chip productionfacility in Landshut, Germany (page14). Optogan’s Markus Zeiler spoke abouthow the company has set about enablingfast adoption of LED lighting. One strategyis to set up a network of “technological andregional champions,” he said, enabling eachcompany to stay focused on its own technologicalareas of strength. One example is atechnical cooperation on AC-LEDs betweenOptogan and Lynk Labs.Another strategy is product modularity.“We need to reduce complexity and keep itsimple for our customers,” said Zeiler, offeringa preview of a scalable chip-on-board (COB)concept which he said was analogous to Legobricks. Finally, he discussed new sales channelsand the value of franchising via remotebusiness owners with regional know-how, asan alternative to setting up branch offices.“This keeps investment low, but enablesglobal branding,” he said.26 NOVEMBER/DECEMBER 2011 LEDsmagazine.comPrevious Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM qMM MQmags| Next Page q qTHE WORLD’S NEWSSTAND ®

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM | Next PageqqM qMMQmagsTHE WORLD’S NEWSSTAND ®___________Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM qMM MQmags| Next Page q qTHE WORLD’S NEWSSTAND ®

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM | Next PageqqM qMMQmagsTHE WORLD’S NEWSSTAND ®LED DriversBuck/Boost LED Drivers - From 1W to 100W.5 Year WarrantyHighest EfficiencyDimming down to 0%TRIAC DimmingAC or DC InputFor Application Support contact yourlocal RECOM sales contact or go to:www.recom-power.comPrevious Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM qMM MQmags| Next Page q qTHE WORLD’S NEWSSTAND ®

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM | Next PageqqM qMMQmagsTHE WORLD’S NEWSSTAND ®conferences | STRATEGIES IN LIGHT EUROPESIL Europe technology track focuseson design, from optics to luminairesThe technology track at Strategies in Light Europe featured several presentations specifi cally aimedat selecting the right materials, optics, drivers and luminaire designs to best take advantage of LEDtechnology, writes LAURA PETERS.The Strategies in Light (SIL) Europeconference and exposition was heldin Milan, Italy on October 4-6 andfeatured two days of discussion regardingthe technological developments thatgo into solid-state lighting (SSL) products.A key message of these presentationsrings true: LED lighting has matured to thepoint where luminaire design, whether itis for street lights, recessed downlights orintegral replacement lamps, must bringtogether optimized drivers, optics andthermal design to best take advantage of allthat LED technology has to offer. SIL Europealso featured parallel sessions in the MarketTransformation track (page 21).Luminaire designHans Laschefski, a consultant with AlanodAluminium-Veredlung GmbH in Ennepetal,Germany, discussed a trend toward multiplereflectors as a means to control glarewith high-power arrays of packaged LEDs.As the industry moves to smaller, denserarrays, glare increases and must be managedto provide an acceptable user experience.“When evaluating glare, people oftentalk about the average luminance, but sinceLEDs are spot-light sources, we should evaluatethe spot illuminance, which is unfortunatelydifficult since the necessary measurementequipment is not typically available,”he explained.Laschefski showed several advancedreflector designs, all of which do not uselenses directly on the packaged LEDs butrather have the LEDs facing angled mirrorsand reflectors. This helps to improve the lightLAURA PETERS is a Senior Technical Editorwith LEDs Magazine.distribution, achieve bettercolor mixing, andreduce glare. One of theadvantages to havingvery-high reflectivityfrom aluminum-basedalloys (95-98% reflectancewith Alanod'sMiro and Miro Silverreflectors) is that multiplereflections can eliminate the observationof a point-light-source by a person lookingdirectly at the luminaire. For instance, inthe Deflecto luminaire street light by AriannaLEDof Padova, Italy (Fig. 1), the multiplereflections sufficiently scatter the light. “Inthese designs, you cannot even tell the lightMultiple reflector light patternFIG. 1. Defl ecto street lights utilize multiple refl ections toeliminate point-light-source glare. Inset: Light distributionpattern from luminaire (source: AriannaLED).source is an LED,” Laschefski said.Laschefski stated that by separating theLEDs from the optics, the problem of lensaging can be controlled. He explained thatwhen LEDs are closely coupled to optics inan air-tight environment, volatile organiccompounds (VOCs) used in LED assemblyLEDsmagazine.com NOVEMBER/DECEMBER 2011 29Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM qMM MQmags| Next Page q qTHE WORLD’S NEWSSTAND ®

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM | Next PageqqM qMMQmagsTHE WORLD’S NEWSSTAND ®conferences | SIL EUROPEmay permeate the silicone dome. Light exposurecauses the VOCs to oxidize, creating adiscoloration of the silicone. If, instead, theLED emitters are not contained in an airtightenvironment, VOCs have a chance todiffuse out and not interfere with the opticaltransmission.The importance of visual comfort with LEDluminaires was also emphasized by GiorgiaTordini, an optical designer with Philips ProfessionalLighting Solutions, who presented“The visual barrier: Designing the nightappearance of an LED product.” She definednight appearance as a person's visual perceptionwhen a light is first switched on in itsapplication. Very high luminance from LEDlight (108 cd/m²) can cause glare, which is anuncomfortable reaction to brightness. Tordininoted that glare is different from photobiologicaldamage, which is caused mainly bylight in the UV realm.Tordini described the optical system ofPhilips’ DayZone luminaire for office lighting,which has a task light in the middle anda separately-controlled outer ring-light forambient lighting. The luminance of the outerring is 3x smaller than that of the inner portion.The luminance limit for work spaces,according to British Standard EN-12464,is 1000 cd/m² at a 90-degree to 65-degreeangle from the vertical axis.Tordini explained that the optical designuses primary optics at the LED level (whichis a multi-LED package) to convert the lightdistribution into a controlled beam. Theplastic optics consists of a microlens arrayfabricated from polymethylmethacrylate(PMMA). This serves to minimize chromaticaberration due to first-order interference,while enhancing scattering to allow auniform visual appearance of light. Transmittancethrough the PMMA film is 92%.This patterned film is available in roll-torollsheets and therefore is flexible to applyin different shapes and sizes. Beyond thisprimary optic, a secondary optic, consistingof a hollow prism ring, modifies the light distributionand controls the light level transmittedto the target surface.Achieving omni-directionalityMarkus Hofmann, a senior developmentengineer with Osram GmbH of Munich,Germany, presented the pros and consof four different approaches to achievingomni-directionality with integral lampsfor residential applications. He said thatomni-directionality can be achieved usinglight guides, reflectors, a remote phosphoror a three-dimensional (3D) arrangementof LEDs.The key advantage of using light guidesOmni-directional lamp in base-up positionRepeat measurements invertical 45° and 90° planesfrom initial planeEnergy Star program requirements for integral LED lamps180°is that an incandescent-like bulb in appearancecan be achieved. However, there isgreat light loss and low efficiency associatedwith this approach, and meetingEnergy Star specifications (Fig. 2) is verydifficult. As a result, light-guide approachesare currently limited to low-lumen-output,design-driven applications.Meeting Energy Star requirements ismuch more practical if reflectors are usedinside the bulb to direct the light. Anotheradvantage is that a classical bulb designis possible. Hofmann said that reflectorsinside retrofit lamps currently work bestfor lamps with medium lumen output.When it comes to achieving high lumenoutput, the remote phosphor approach issuitable because light losses are low andthe phosphor is compatible with externalaluminum fins that function as the heatsink. The downside, particularly in today’smarket according to Hofmann, is the highcost of remote phosphors that contain rareearthmaterials. Assembly of the bulbs isalso a more complex process, he said, butEnergy Star requirements can be met.0°At least 5% of total flux (lm)in 130°-180° zone135°Luminous intensity (cd) at any anglein the 0°-135° zone shall not differfrom the mean intensity for the entire0°-135° zone by more than 20%.Source: OsramFIG. 2. Omnidirectionality is one of the more diffi cult requirements of Energy Star.Alternatively, a 3D arrangement of theLEDs can meet high-lumen-output needsand also meet Energy Star requirements.Hofmann stated that 60W-equivalent (850lm) and 75W-equivalent (1060 lm) lampsthat meet Energy Star requirements withgood CRI, CCT and lifetime have been fabricatedusing 3D approaches. “Realizationof 100W-equivalent lamps with 3DLED arrangements will be coming soon,”he added.Another presentation in the same sessionrevealed a less-traditional approach tofabricating and marketing retrofit lamps.Martijn Dekker, CTO of Lemnis Lighting,an LED lamp maker based in the Netherlands,announced that Lemnis has enteredinto a multiyear commitment with a largeretailer to develop and market cost-effectiveLED lamps. The first products are 400-lm and 200-lm lamps, which will be introducedin European stores soon. Althoughnot confirmed by Dekker, the retailer isthought to be Sweden-based Ikea. WhileDekker noted that the lamps do not meetEnergy Star requirements and have ashorter lifetime rating (20,000 hours) thanmost replacement lamps, the overridinggoal in development was achieving acceptableconsumer price points while deliveringquality lamps.“The price target for these lamps was lessthan €9.99 ($13.77) for the 45W-replacementlamp and €6.99 ($9.64) for the 25W-replace-30 NOVEMBER/DECEMBER 2011 LEDsmagazine.comPrevious Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM qMM MQmags| Next Page q qTHE WORLD’S NEWSSTAND ®

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM | Next PageqqM qMMQmagsTHE WORLD’S NEWSSTAND ®conferences | SIL EUROPENormalized system efficacy (%)120100ment,” explained Dekker. The 400lm lamp offers a CCT of 2700Kand a CRI above 85. The LEDdesign combines two red LEDswith four phosphor-convertedblue LEDs, but the company plansto move to a phosphor-only arrayin 2012 products.Dekker referred to the novelbusiness agreement with Lemnis’partners as a virtual verticallyintegratedcompany involvingthe retailer, the lighting manufacturer,an LED fabrication partnerin India and other supply partners.These companies are sharingthe project risk to achieve long-termvolume sales of LED lamps priced at $8/klmat the lamp level. “A non-integrated supplychain leads to a stacking of profit marginsthrough the supply chain,” he said, whichlimits the industry’s ability to hit low commercialprice points.80604020LEDsystem efficacyCFLsystem efficacyHIDsystem efficacy00 20 40 60 80 100Input power (%)Source: Harvard EngineeringFIG. 3. System effi cacy of various technologies when dimmed.Optimizing opticsAmong all retrofit lamps, perhaps the LEDbasedMR16, because of its small size, is one ofthe more difficult to design. Mike Bean, headof design and development at Carclo TechnicalPlastics (CTP), a designer and manufacturerof optical components based in London, UK,described the MR16 halogen lampas a tough act to follow. “MR16design using LEDs is quite a challenge…despitethe fact that thereare several commercially-availablereplacement lamps, most donot come close to the 50W halogenin performance,” said Bean.According to the US Departmentof Energy’s (DOE’s) Caliper testingof LED-based MR16 lamps, while50W-equivalent performance isthe goal, typical measurementsare closer to those of 25W- or35W-equivalent lamps (Fig. 3).To achieve the required centerbeamintensity and a narrow overall beamangle, one key to the lamp design is to combinesmaller LEDs with focusing optics.Smaller LEDs and total internal reflection(TIR) optics allow the beam angle to bereduced from 40 to 27˚, while still delivering2250 cd at 27˚. In this design, the 30-mm-__________Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM qMM MQmags| Next Page q qTHE WORLD’S NEWSSTAND ®

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM | Next PageqqM qMMQmagsTHE WORLD’S NEWSSTAND ®conferences | SIL EUROPEIntensity (cd)8000700060005000400030002000diameter optic was optimallyplaced 15 mm above the multichipLED source, allowing thereflector to fit within the specifiedgeometry of the MR16 lamp(per ANSI C78.24 specification).Bean said that in addition tohelping with the beam angle, themulti-chip LED approach alsoaffords more driver options,including serial or parallel operation.The reference design useda Diodes 1.5A driver, a Cree MT-GLED package and a Carclo TIRoptic to deliver an initial outputof 611 lm at 10.1W (61 lm/W).SIL presentations alsoaddressed luminaire design elementsrelated to product life. Klaus Reinartz,director of the global LED programat Bayer MaterialScience LLC (BMS) inLeverkusen, Germany, explained howadvanced polycarbonate materials can50Wequilvalent35Wequilvalent20Wequilvalent50W reference design1000Round-11 Caliper results00 10 20 30 40 50 60Beam angle (°)offer increased transparency in a thinneroptical lens with a much smaller yellownessindex than previous-generation materials.The company’s Makrolon products are stableagainst 90-degree LED light with anSource: CTPFIG. 4. Energy Star center-beam intensity targets for MR16lamps, showing seleted Caliper results and reference design.intensity of 46 lm/cm², and thecompany is currently performingtrials at higher temperaturesand light intensities.Advanced polycarbonatematerials can be injectionmoldedinto a wide variety ofshapes and sizes to meet LEDlight transmission, shapingand diffusing needs. One of thenewer developments that Reinartzdescribed is thermally conductivegrades of polycarbonate(up to 40W/m∙K), which canbe custom-molded to act as alighter, more flexible heat sinkthan aluminum options.Driver and dimmer designRasib Khan, an engineering managerwith Harvard Engineering plc, based inWakefield, UK, presented a comparisonof dimming system efficacy among LED,Complex componentsneed reliable protection.When you need to precisely spray and dispense liquid coatings and materials, the SCS Precisioncoat selectivespray and dispense coating system provides maximum accuracy and flexibility. The 3-5 axes system offersa wide array of industry-leading optional features to meet any production requirement, includingprogrammable tilt and rotate, needle calibration, vision system, offline programming and a barcode reader.The new SCS Precisioncoat potting platform automates the potting process to increase production accuracyand efficiency. The PC-controlled system allows users to precisely control the volume of material dispensed,can be configured with one head or multiple heads, and can dispense one or two-part materials.Contact SCS to find out more about our innovative solutions for your advanced technologies.World Headquarters (US): 317.244.1200www.scsequip.com32 NOVEMBER/DECEMBER 2011 LEDsmagazine.comPrevious Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM qMM MQmags| Next Page q qTHE WORLD’S NEWSSTAND ®

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM | Next PageqqM qMMQmagsTHE WORLD’S NEWSSTAND ®Ultra-PreciseDispensingEssential for manufacturingSide-View LEDs for smartphones,tablets and e-readersConsistent weight every timeTight color qualityMore units per hourAutomatic closed-loop controlFind out more about Jet Dispensingat www.NordsonASYMTEK.com/LEDsWithNordson ASYMTEKjetting systems, 0.1 to 0.2 mmdots of silicone phosphor areeasily dispensed tofill the 0.4 mm cavity.The Spectrum Series jetting system automatically maintainsconsistent shot weight for improved process capability (CpK) whileensuring higher UPH. Using CPJ+, available only from NordsonASYMTEK, process variability is reduced to maintain a constant Takttime. The system is easy to program and adjustments are not requiredafter set-up, keeping your process under machine control.Email: info@nordsonasymtek.comUSA: +1.760.431.1919China, Shanghai: +8621.3866.9166China, Beijing: +8610.8453.6388China, Guangzhou: +8620.8554.0092Europe: +31.43.352.4466India: +91.44.4353.9024Japan: +81.3.5762.2801Korea: +82.31.765.8337S.E. Asia/Australia: +65.6796.9514Taiwan: +886.2.2902.1860nordsonasymtek.comPrevious Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM qMM MQmags| Next Page q qTHE WORLD’S NEWSSTAND ®

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM | Next PageqqM qMMQmagsTHE WORLD’S NEWSSTAND ®conferences | SIL EUROPECFL and high-pressure sodium (HPS) lightsources. The greatest energy savings areassociated with using LEDs and appropriatedimming levels. As a comparison, HPSsources can only be dimmed to approximately40% of their maximum lumen outputand system efficacy is compromised withall levels of dimming (Fig. 4). In other words,higher input power is required to producethe same lumen output. For example, a 60WCosmo luminaire with Harvard DALI ballastat a 50% light-output level requires approximately67% of input power.System efficacy is better with CFLs, wherehigh efficacy is maintained down to about40% lumen output levels. For a typical fixture,30% lumen output requires approximately35% input power. However, below a40% dimming level, CFLs suffers from cathodeand driver inefficiencies.LEDs are easier to dim and hypotheticallycan be dimmed readily to as low as1%. System efficacy is excellent from 100%LM-80 / LM-79 TEST SERVICESSetting the Standard for LED MeasurementORBoptronix>DဒϬ>DϳဓdĞƐƟŶŐ^ĞƌǀŝĐĞƐKƌďKƉƚƌŽŶŝdžŝƐƚŚĞĮƌƐƚŝŶĚĞƉĞŶĚĞŶƚϯ ƌĚ ƉĂƌƚLJ/^KϭϳϬϮϱĐĐƌĞĚŝƚĞĚh^>ĂďŽƌĂƚŽƌLJŽīĞƌŝŶŐĐŽŵƉůĞƚĞ>DဒϬ>ƵŵĞŶDĂŝŶƚĞŶĂŶĐĞdĞƐƟŶŐEZ'z^dZWZĞĐŽŐŶŝnjĞĚK>ŝWZ^^>>ƵŵŝŶĂŝƌĞdĞƐƟŶŐĚĚŝƟŽŶĂů^ĞƌǀŝĐĞƐ>LJĞ^ĂĨĞƚLJǀĂůWƌŽĚƵĐƚdĞƐƟŶŐĨŽƌZŝƐŬ'ƌŽƵƉůĂƐƐŝĮĐĂƟŽŶdK>ŚĂƌĂĐƚĞƌŝnjĂƟŽŶ^ĞƌǀŝĐĞETO-S20-P6-HPAETO-TEC-100to around 20% of light output. For instance,a 50W-equivalent luminaire with Harvard700 mA DALI driver at 50% light outputonly requires 44% input power. With currenttechnology, system efficacy becomesimpacted by driver efficiency below 20% oflight output.According to Khan, simple analogswitch dimming (0-10V) works well on asmall scale, but requires too much cable forlarge-scale implementations. More expensivecontrol options such as DALI can providegreatwer flexibility for projects of allsizes and are re-configurable. However,DALI and other approaches require furtherwork to fully maximize control efficiencyand power factor over the control range.Ultimately, Khan expects the industry tomove to wireless intelligent control systemscapable of plug-and-play operation.Also in the drivers session, Steve Roberts,technical manager at Recom, Austria,discussed the significant impact that&RPSOHWH6(59,&(6&RPSOHWH6ŚĂƌĂĐƚĞƌŝnjĂƟŽŶ^LJƐƚĞŵƐddĞŵƉŽŶƚƌŽůǁŝƚŚdƐdĐdũDŽŶŝƚŽƌŝŶŐ,ŝŐŚůLJĐĐƵƌĂƚĞ>^ƉĞĐƚƌĂů&ůƵdžDĞĂƐƵƌĞŵĞŶƚƐĂŶĚWtDWŽǁĞƌ^ƵƉƉůLJŽŶƚƌŽůƐE/^ddƌĂĐĞĂďůĞůĞĐƚƌŝĐĂůdŚĞƌŵĂůKƉƟĐĂůĂƚĂƵƚŽŵĂƚĞĚĂƚĂĐƋƵŝƐŝƟŽŶĂŶĚŶĂůLJƐŝƐdŽŽůƐϰtŝƌĞsŽůƚĂŐĞĂŶĚƵƌƌĞŶƚDĞĂƐƵƌĞŵĞŶƚƐ,ĂƌĚǁĂƌĞ^ŽůƵƚŝŽŶƐŝŶĐůƵĚŝŶŐZĞƚƌŽĨŝƚŽƌƵƐƚŽŵ25%237521,;,1&6DOHV#2UE2SWURQL[FRP3OHDVHYLVLW2UE2SWURQL[FRPIRUDIXOOOLVWRISURGXFWV _____________VHUYLFHVhigh temperature can have on luminairereliability. He made several design recommendationsfor minimizing temperatureincreases in LED luminaires includingmounting the LEDs so that they havelow thermal impedance to the heat sinkand mounting the driver away from theLEDs and heat sink. The heat sink shouldbe designed for the most efficient size/efficiencyratio. Thermal derating can be usedto reduce the LED current if the junctiontemperature approaches specification limits.Roberts further recommends limitingthermal cycling and allowing for a singleLED failure in multiple LED installations.Input-output voltage transients can bemanaged by using spike protection as wellas short input cables with relatively-longeroutput cables.Regarding triac dimmers, Roberts recommendsthat engineers consider the timingof triggers and the effect on the driverelectronics. Rather than separate AC/DCballasts, a centralized DC-power-distributionapproach should be used with a largeAC/DC power supply feeding multiple DC/DC LED drivers. Finally, Roberts recommendsconsideration of the reliability ofevery component in the luminaire system.Designing power-distribution networksA presentation by Marc Ottolini of iSoteraLtd of Hoddesdon, UK, considered the utilityof DC-power-distribution networks forSSL. Ottolini compared four scenarios –the legacy architecture, a centralized DCStar approach where one AC/DC supplyfeeds DC/DC drivers, a DC grid where lowvoltageDC leaves the AC/DC supply, or acentralized high-frequency AC (HFAC) busapproach. For each approach, he looked atsimplicity of installation, cost, safety, reliabilityand controllability.He concluded that there is no compellingbenefit to implementing a full-DC-powerdistributionsystem for LED lighting. However,a centralized (bulk) power processingapproach can be advantageous if up anddown (2-stage) conversion can be made efficientenough, which depends on the diversityof the LED load. He finalized with thestatement that energy-efficiency benefitsalone (2-5%) do not provide enough impetusto begin setting new standards.34 NOVEMBER/DECEMBER 2011 LEDsmagazine.comPrevious Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM qMM MQmags| Next Page q qTHE WORLD’S NEWSSTAND ®

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM | Next PageqqM qMMQmagsTHE WORLD’S NEWSSTAND ®RELY ON ULAs lighting technology evolves, so does UL. In addition to product safetycertification, we also provide industry-leading performance testing,environmental programs and robust training initiatives.UL is widely known for our dedication to quality, technical expertise andbeing a symbol of trust. From code authorities to specifiers and consumersto retailers, our 100-year history of advancing safety demonstrates ourcommitment to protecting people, products and places.When you rely on UL for your lighting product needs, your future is bright.VISIT WWW.UL.COM/BRIGHT___________________Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM qMM MQmags| Next Page q qTHE WORLD’S NEWSSTAND ®

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM | Next PageqqM qMMQmagsTHE WORLD’S NEWSSTAND ®standards | TM-21The elusive “life” of LEDs:How TM-21 contributes to the solutionThe newly-introduced TM-21 document presents a method for lumen-depreciation projection basedon LM-80 data, enabling LED lifetime extrapolations beyond 6000 hours, says ERIC RICHMAN.In August 2011, the IlluminatingEngineering Society (IES) published theTM-21 document entitled “Lumen degradationlifetime estimation method for LED lightsources.” TM-21 is the IES-recommendedmethod for projecting lumen degradation ofan LED package, array or module based ondata collected according to LM-80.The lighting community expects TM-21 tobecome the standard method for projectinguseful LED lighting product life at realisticoperating temperature. This article presentsthe development process behind TM-21, andclarifies how and when to apply the lifetimeextrapolation method to arrive at reasonableand useful estimations.Lumen output(%)Typical "life" of standard lighting technologies10510095908580LED75INC FL HID706560551,000 11,000 21,000 31,000 41,000 51,000 61,000Hours of operationRepresentative only - not to scaleFIG. 1. Lumen degradation and failure behavior for incandescent (INC), fl uorescent(FL), high-intensity discharge (HID), and LED lamps.Why TM-21 and why now?We are all familiar with the very real butsometimes exaggerated long-life attributesof LED technology. Not the least of theseis the potential for very long life that helpsmake it an attractive design choice. Thetrick has been and continues to be how tomeasure or estimate this longevity to provideassurance to users of this technology’sreliability (life) compared to other options.We also understand that the overall reliabilityof a complete LED lighting fixturecan be affected by the reliability of individualproduct components (driver, lens, etc.)and should be accounted for in lifetimeestimations.The useful life of standard lighting technologiesis defined as the time to filamentor cathode failure. For most of these lamps,the time period prior to failure exhibitsacceptable levels of light output, as shownERIC RICHMAN (eric.richman@pnnl.gov) is a Senior Research Engineer with Pacific NorthwestNational Laboratories and follows standards development for the DOE SSL program (www.ssl.energy.gov). PNNL (www.pnl.gov) is a research laboratory of the US Department of Energy.______with the solid lines in Fig. 1. This makes iteasy to determine when to replace the lamp.However, LEDs do not have filament burnoutthat conveniently announces the endof life (dashed line in Fig. 1). Further, therapid development of the technology andthe desire to bring products to market ina timely manner does not allow for actualtesting verification of the long lives claimed(100,000 or even 35,000 hours). As a result,the industry has come to accept a definitionof the end of the useful life of an LED as thepoint when it no longer provides a specifiedlevel of light output.And finally, the life and performance ofLED lighting products depends greatly onexcess heat retained at the diode. This is whyLEDs require testing at multiple temperaturessuch that when a source is installed ina luminaire, its actual operating temperaturecan be measured and lumen depreciationof the product can be derived.Therefore, to serve the solid-state lightingindustry, the Technical Procedures Committee(TPC) of the IES proceeded to developappropriate tests for use in rating LED productlongevity. The initial need was a measureof the basic lumen degradation of LEDsource components identified by a module,package, or array of diodes and this came inthe form of LM-80. Importantly, LM-80 onlyspecifies how to measure lumen depreciationto a minimum of 6000 hours (but recommendstesting to 10,000 hours or longer).LM-80 stops short of using that data to estimateany depreciation after that, which iswhere TM-21 comes in.The TM-21 working group (WG) as partof the IES TPC was formed to develop thelumen depreciation projection methodand spent over three years exploring manyoptions. The WG evaluated various projectionoptions starting with an analysis of variousmathematical, engineering-based modelsto provide effective depreciation fit and auseful projection method.LEDsmagazine.com NOVEMBER/DECEMBER 2011 37Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM qMM MQmags| Next Page q qTHE WORLD’S NEWSSTAND ®

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM | Next PageqqM qMMQmagsTHE WORLD’S NEWSSTAND ®standards | TM-21Next, the WG analyzed LED lumen maintenancebehavior using over 40 sets of LM-80-08test data (20 sets with 10,000 hours or more)collected from four major LED manufacturers.The working group also examined theaccuracy of proposed projections using variousproposed models and LM-80 data thatextended up to 15,000 hours.Insight from LED manufacturers’ dataThis analysis showed that the LED lumendepreciation trends often change after 6000hours in one way or another and there is noreliable and consistent approach to predictsuch trends from 6000-hour data points.Ts,1, ( 0 C) 55Ts,1, (K) 328.15a11.684E-06B1 0.9639Ts,2, ( 0 C) 85Ts,2, (K) 358.15a23.354E-06B2 0.9525Ea/kB 2699A6.283E-03B09.582E-01Ts,i, ( 0 C) 70Ts,i, (K) 343.15ai2.413E-06Projected L70(Dk) 130,131Reported L70(Dk) >60,000TABLE 1. Parameters of interpolationusing 10,000 hours of LM-80 data for insitucase temperature Ts,i of 70˚C.Even a 10,000 hour stream of data is oftennot sufficient to provide rigid statistical confidencein an extrapolation of a decay curveout to large numbers such as 35,000 hours.In addition, the LED industry understandsthat degradation associated witheffects other than the diode itself tends tomanifest earlier in life rather than later. TheWG concluded that the most reasonableapproach to extrapolation of lumen degradationwas to avoid using any initial variabledata. This initial data variability is commonlyassociated with an early rise in outputfollowed by the eventual decline, identifiedas a hump in the data. Instead, by utilizinga fit to the later data streams (Figs. 2 and 3),a more accurate representation of the product’slumen degradation curve is obtained.What TM-21 is and is not!First, TM-21 does not determine a traditionallife or time-to-failure like we are used to forother lighting sources.What TM-21 does provide is a projectionof the lumen maintenance of an LED source(package/array/module) based on data collectedaccording to LM-80. This projectioninformation can then be used to project theexpected lumen degradation of the lightsource as part of a complete system (fixture).It is important to note, however, that TM-21is not a complete lifetime estimation tool.TM-21 does make use of all data providedin an LM-80 test format. LM-80 requires6000 hours of data at 1000-hour increments,but the TM-21 WG determined that longerstreams of data and data taken at shorterintervals (less than 1000 hours) will providefor a better estimate. The methodology firstnormalizes the provided data to 1 (100%) at0 hours and averages each point for all samplesof the device for each test condition(temperature).TM-21 also provides a suggested samplesize of 20 LED packages, arrays or modules.Based on an evaluation of the uncertaintyof measurement at various samplesizes, a larger sample size (30) does notsignificantly increase the uncertaintyand smaller size (10) would significantlyreduce the uncertainty of the degradationestimates.How it worksAs discussed previously, later data tends toexhibit the more characteristic decay curvethat is of interest. So for 6000 hours of data(LM-80 minimum) and up to 10,000 hours,TM-21 applies curve fitting to the last 5000hours of collected data. For collected datagreater than 10,000 hours, TM-21 uses thelast half of the data.The method then applies an exponentialleast-squares-curve fit to the data:Φ(t) = B exp(-αt)Where:t = operating time in hours;Φ(t) = averaged normalized luminousflux output at time t;Relative lumen maintenance1.101.081.061.041.021.000.980.960.946k hour fitTest data10k hour fit0.920.900 5000 10,000Operated hoursRelative lumen maintenance1.051.000.950.900.85Test data6k hour fit10k hour fit15,000FIG. 2. Later TM-80 data points providea better estimate of long-term lumenmaintenance.0 5000 10,000 15,000Operated hoursFIG. 3. As also shown in Fig. 2, a fi t toLM-80 data collected later provides thebest estimate of lumen maintenance forLEDs.B = projected initial constant derivedby the least-squares-curve fit;α = decay rate constant derived by theleast-squares-curve fit.And a projected lumen maintenance valueis derived using:Lp = ln(100∙B/p)/αWhere:Lp= lumen maintenance life in hourswhere p is the maintained percentage of initiallumen outputThis process can accommodate any useridentifiedlevel of light output (i.e. L70 or L50).If the desired light output level is reachedduring the course of LM-80 testing, then thattime value is reported.During the development of the method, it38 NOVEMBER/DECEMBER 2011 LEDsmagazine.comPrevious Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM qMM MQmags| Next Page q qTHE WORLD’S NEWSSTAND ®

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM | Next PageqqM qMMQmagsTHE WORLD’S NEWSSTAND ®standards | TM-21became clear that limited 6000-hour data canproduce mathematical results that are notnecessarily rational or believable. For example,flat or increasing delay curves would beunreasonable for LED products. Clearly, reasonablelimits on predictions are needed.The WG analyzed 40 sets of data to determinemodel-fit uncertainty and its relationshipto prediction limits. The recommendedextrapolation limits are:• For a sample size of 20 units, the maximumprojection = 6× the test duration• For a sample size of only 10 units, themaximum projection = 5.5× the testduration.TM-21 also provides for interpolatingbetween test data curves to determine theactual degradation characteristics the productwill exhibit when installed in a fixturewhere heat conditions will change. When thein-fixture measured temperature is withinthe LM-80 test temperatures (55°C, 85°C, andmanufacturer chosen), then TM-21 prescribesthe use of the Arrhenius equation to interpolatebetween test temperatures. The Arrheniusrelationship accounts for the temperatureeffect on decay rate constants, which iscritical for temperature-dependent LEDs.For instance, Table 1 presents an exampleof an extrapolation with an in-fixturetemperature of 70˚C with the graphicLumen maintenance(%)100908055°Cdata85°C55°Cdata 70°C85°C700 10,000 20,000 30,000 40,000 50,000 60,000Time (h)FIG. 4. Degradation curves from measured data and fromin-fi xture interpolation at 70˚C.results in Figure 4. Extrapolation outsideof LM-80 test temperatures is not recommendedor supported.The TM-21 document provides a nomenclaturefor results to provide uniform reportingbetween products. The general form is:Lp (Dk)Where:p = the percentage of initial lumen outputthat is maintainedD = the total duration of the test in hoursdivided by 1000 and roundedFor example:L70(6k) = 34,000 hours represents resultsat 6000 hours of test dataL70(10k) = 51,000 hours represents resultsat 10,000 hours of test dataL70(6k) > 36,000 hours represents resultswith the 6 times rule appliedL70(4k) = 4400 hours represents results ata value reached during testing.The methodology is provided in theTM-21 document as formulas and procedurebut can be developed into spreadsheetsor other software-tool formats. Themethod can also be misapplied in softwareprograms, so a set of examples is includedfor users to check the results.Where does TM-21 fit in the industry’scharacterization of LED life?TM-21 is the result of extensive analysis andit presents a realistic method of projectinglumen maintenance of LED packages,arrays and modules in actual operating conditions.However, diode lumen degradationover time is only one of many possible LEDproduct-degradationmechanisms. The industryis seeking to betterunderstand componentreliability metrics suchas driver life, and theeffect on lighting productperformance.The TM-21 documentmay be applied in variousways. It can be usedby laboratories, manufacturers,or othersas defined by the programor organizationrequiring its application.TM-21 data can berequested as part of LM-80 testing or appliedby the manufacturer of an LED product.TM-21 is expected to achieve widespread useby organizations and program certifications(e.g. Energy Star) as part of their required documentationof performance.____________________LEDsmagazine.com NOVEMBER/DECEMBER 2011 39Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM qMM MQmags| Next Page q qTHE WORLD’S NEWSSTAND ®

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM | Next PageqqM qMMQmagsTHE WORLD’S NEWSSTAND ®EBV Elektronik and Avago – Your Strong Partners,Especially for LED Lighting ProductsAvago Technologies is one of the largest producers of visibleHigh Power LEDs in the world and ships billions of productsannually. Known for its High Power LEDs’ performance,efficiency and reliability, Avago offers an extensive portfolio ofproducts at globally competitive prices.From a supplier of discrete LEDs, Avago has emerged tooffer total solutions for illumination and lighting applications.Key products include high brightness and high power LEDs,PLCC surface-mount LEDs, and display backlighting modulesolutions.These LEDs and display modules address a wide range ofmarkets, including electronic signs and signals, automotive,solid state lighting and LCD display backlighting.EBV Elektronik provides a narrow binning service for selectedAvago products, delivery from stock as well as the full rangeof associated products, like drivers, lenses, etc.REGISTER NOW to find more information and towin an MR16 LED spotlight and get FREE LED samples:www.ebv.com/avagoledDistribution is today.Tomorrow is EBV!www.ebv.comPrevious Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM qMM MQmags| Next Page q qTHE WORLD’S NEWSSTAND ®

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM | Next PageqqM qMMQmagsTHE WORLD’S NEWSSTAND ®Avago´s Next Generation Brighter Performance 0.5W PLCC-4 White LEDsNow Available – For All Your Lighting NeedsThe world’s brightest 0.5W PLCC-4 SMT LED has been designedto optimize your products for backlighting, automotivelighting, decorative lighting, cabin lighting, shop lighting andother lighting applications. This mid-power LED series has awide viewing angle of 120°. It comes in an industry-standardPLCC-4 package (3.2 x 2.8 x 1.9 mm) – enhanced for betterheat dissipation to sustain high drive currents and to producehigher light output with better flux performance.EBV and Avago support narrow colour and flux bin selectionsfrom inventory with various options in Warm, Neutral andCool White.KEY FEATURES• Minimum 43 Lumen at 150 mA in Cool White• Low thermal resistance 40°C/W• Operating temperature –40 to +120 °C• AEC-Q101 Automotive qualified• Full range of colors, including cool, neutral and warm whiteREGISTER NOW to find more information and towin an MR16 LED spotlight and get FREE LED samples:www.ebv.com/avagoledDistribution is today.Tomorrow is EBV!www.ebv.comPrevious Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM qMM MQmags| Next Page q qTHE WORLD’S NEWSSTAND ®

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM | Next PageqqM qMMQmagsTHE WORLD’S NEWSSTAND ®THE LATESTAND GREATESTLED LIGHTING> A world of 10,000 LED lighting components and design solutions> LEDs, Power and Thermal management, Interconnect and Opticproducts available> Global portfolio of industry leading manufacturerswww.farnell.com/lightingwww.element14.comDesign with the bestPrevious Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM qMM MQmags| Next Page q qTHE WORLD’S NEWSSTAND ®

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM | Next PageqqM qMMQmagsTHE WORLD’S NEWSSTAND ®lighting | MODULES AND STANDARDSLED modules simplify luminaire designwhile Zhaga closes on initial specificationsLED-based modules for SSL can simplify product design and even make products fi eldupgradeable,reports MAURY WRIGHT. Zhaga standards will yield interoperable modular productsfrom multiple vendors.Modular LED light engines can allowluminaire makers to develop solidstate-lighting(SSL) products withoutfacing the technical details of electronicdriver circuits, LED selection and configuration,thermal management, and opticsdesign. Manufacturers should understandthe basics and importance of these product-designdisciplines, but a proven modulevendor can ensure the details get properattention. The modular approach can speedproduct development and enable upgradeableproducts. Today, the available modules areproprietary to each manufacturer, but standardssuch as those the Zhaga Consortiumhas under development will yield interoperablemodules from multiple vendors.Modular LED light engines arequickly gaining favor. A number ofmajor LED manufacturers and LEDlightingcompanies including Cree,Osram, Philips, and GE Lighting havemodules available for a variety of applicationsranging from indoor downlightsto outdoor street lights.Let’s start by defining some terminologyfor the scope of this article becausewords such as light engine and modulearen’t used consistently in the SSLindustry. Zhaga (see www.ledsmagazine.com/features/8/11/4 for background informationand an update on Zhaga activity)defines a light engine as the combination ofan LED module and its associated controlgear or driver.Zhaga sticks with the term light enginewhether or not the driver is integrated intoa modular package along with the LEDs.Zhaga is developing specifications forlight engines with integrated control gearand light engines with separate controlgear. In the latter case the driver is alsoessentially a packaged module or subsystem.For this article, we will use the terms LEDmodule and LED light engine interchangeablyand simply specify whether a driver isintegrated in the module. Indeed the modulemakers mentioned above use the termmodule whether or not a driver is included.We will include discussion of modules thatfasten into a luminaire using screws or otherfasteners, and modules that use some formof snap-in or twist-lock mounting mechanism.The latter are sometimes referred toas tool-less or tool-free designs, and ZhagaPhilips Fortimo DLM modules in Hoffmeister luminaireslight the parliament building in Dusseldorf.uses the term socketable if the module canbe installed without tools.The modular advantageModules can offer a number of advantagesover what some call integral luminaireswhere the fixture manufacturer assemblesthe requisite components including LEDsand the driver ICs that precisely match theapplication at hand into a finished product.As mentioned, buying an off-the-shelfmodule, and perhaps a driver, greatly simplifiesthe product-development processdelivering the aforementioned advantageLEDsmagazine.com NOVEMBER/DECEMBER 2011 43Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM qMM MQmags| Next Page q qTHE WORLD’S NEWSSTAND ®

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM | Next PageqqM qMMQmagsTHE WORLD’S NEWSSTAND ®lighting | MODULES AND STANDARDSin speedier development.Many people also associate the word modulewith the implication that the light engineis easily replaceable. In contrast, many integralluminaires on the market require a completefixture replacement if the light enginefails of if an upgrade to greater lumen outputor perhaps a different color temperature isdesired. Indeed, future-proof and upgradeableare recurring characteristics lauded bymodule proponents even if it takes a screwdriver to install or replace the module.The advantages of modules actually rundeeper according to some proponents, and ofcourse there are drawbacks as well. Bridgeluxand Molex were among the first companiesto offer a socketable module with thejointly-developed Helieon product introducedlast year (http://www.ledsmagazine.com/news/7/3/21). A press-and-turn actionlocks the Helieon module into a receptaclesocket mounted in the luminaire. The matingaction both secures the module in placeand makes the electrical contact.Supply chain benefitsBridgelux vice president of marketing JasonPosselt said that the modular approach canoffer manufacturers great benefits in the supplychain. He said that a single module formfactor can be used across a wide range of fixtures.Moreover Posselt said, “There is no needfor the luminaire maker to inventory largenumbers of modules.” Instead the luminairemanufacturer can build various fixtures thatare customizable in terms of light output,color temperature, beam pattern, and othercharacteristics based on the particular modularlight engine mated to the fixture. Posseltsaid, “The manufacturer can deliver the fixtureand module separately.”According to Posselt, the typical bill ofmaterials for an SSL luminaire is about a thirdattributable to the LED assembly, a third tothe driver, and a third to the remainder of thefixture. Eliminating the need to buy and stockan inventory of components that are neededto build the LED assembly can reduce theinvestment in inventory significantly.The first generation of Helieon modulesdid not include a driver. At Lightfair 2011 inMay, Bridgelux and Molex introduced the second-generationof Helieon with an integrateddriver. Posselt said, “The DC version didn’tcompletely solve the problem we were tryingto address.” That problem was fully simplifyingthe SSL design process. Posselt added, “Thedriver is a big issue for luminaire makers.”Bridgelux and Molex plan to ship the second-generationHelieon products in Q1 of2012. The companies are fine tuning thedriver design to fit a very confined space.And because the new version will operatefrom line voltage and be user replaceable,the companies are proceeding through theprocess of getting the module UL listed.The tradeoffsThe downside to modules is principally cost.A module may also restrict some of the designelements in a luminaire and therefore the aesthetics.And with modules, luminaire makerswill never have complete photometric featurefreedom, for instance in terms of choosing anexact lumen output or generating a specificcolor temperature with a custom LED mix.But the biggest tradeoff comes back to cost.Modules invariably introduce extra materialssuch as plastic or metal module housings, andcomplex electrical and mechanical connectors.Moreover the cost of separately assemblingthe module is an adder.Module proponents believe that thetechnology will ramp SSL uptake andthe greater manufacturing volumes willreduce the cost premium. Moreoverthe modular approach will likely resonatewith consumers that are accustomedto changing light bulbs rather thanreplacing fixtures. And that’s Zhaga’s missionto develop specifications that standardize amodular approach to interoperable SSL productsrather than having multiple companiesbuilding similar but incompatible products.Menno Treffers, secretary general of theZhaga Consortium, said “The key thing thatwe want to achieve is that the products frommultiple vendors fit together.” UltimatelyZhaga specifications should allow multiplevendors to make compatible light engines.Luminaire makers will also be able to buy adriver from one company, a mechanical housingfrom another, an LED module from yetFrom top: Osram PrevaLED module,Philips Fortimo SLM for spot lights, GEInfusion module, Cree LMR4 module withintegrated driver and optics.44 NOVEMBER/DECEMBER 2011 LEDsmagazine.comPrevious Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM qMM MQmags| Next Page q qTHE WORLD’S NEWSSTAND ®

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM | Next PageqqM qMMQmagsTHE WORLD’S NEWSSTAND ®Flicker-Free Dimming,Blazing PerformanceHigh-performance LED drivers deliver smooth,linear dimming without flickerTexas Instruments’ patent-pending architectures and industry-leading design tools enablestate-of-the-art TRIAC and phase dimming compatibility and performance, enabling aseamless transition to LED lighting technology.LM3445 Key Features• TRIAC-dimmable offline LED driver• Enables LEDs to be used as direct replacement forincandescent or halogen lamp systems interfacedto a TRIAC wall dimmer• Offers 100:1 full-range, uniform dimming• Flicker-free at 100/120 HzLM3450 Key Features• Phase-dimmable LED driver• Integrates active power factor correction andphase dimming decoding• Ideal for dimmable LED fixture applications withoutput powers between 10 W and 100 W• Accepts universal input voltages• Dynamic hold circuitry for excellent dimmingperformance> Learn more> Order samples> Order evaluation moduleswww.ti.com/lm3450www.ti.com/lm3445The platform bar is a trademark of Texas Instruments. © 2011 TIPrevious Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM qMM MQmags| Next Page q qTHE WORLD’S NEWSSTAND ®

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM | Next PageqqM qMMQmagsTHE WORLD’S NEWSSTAND ®lighting | MODULES AND STANDARDSanother, and optics such as a reflector fromstill another.Zhaga’s process and progressZhaga’s approach is based on defining whatit calls the mechanical, thermal, electrical,and photometric interfaces of a light engine.The mechanical elements include shape,dimensions and mounting scheme or socket.The electrical interface includes the connectorand AC- or DC-voltage specification. Thethermal interface defines how cooling elementsin the luminaire housing mate to athermal surface on the module. The photometricinterface includes elements such asthe size of the light emitting surface, lambertianor shaped-beam pattern, and uniformityof light on the task plane.The Zhaga process includes proposal,merger, specification-development, and published-specificationstages. Members of theconsortium that are interested in a particulartype of module submit proposals based ontheir own R&D. Elements of the proposals aremerged by task forces and then converted intospecifications by working groups.Zhaga has approved three light enginespecifications thus far:• A socketable LED downlight engine withintegrated control gear• An LED spotlight engine with separatecontrol gear• A socketable LED light engine with separatecontrol gear.The specifications have not been madeavailable to the public although members ofthe consortium have free access. At this timeno company can claim official Zhaga compliancefor a product because the consortiumis still working on compliance testing procedures.Treffers says that the first productsto carry the official Zhaga logo are monthsaway from the market as opposed to a year,but he can’t offer a more specific projection.Zhaga has four other specifications indevelopment including a street light module,and a rectangular module – a number ofwhich may be connected together for indoorlinear lighting. There are other proposals atearlier stages of the Zhaga process.Designed for ZhagaIn reality, there are already modules on themarket that are based on Zhaga standards,or more correctly that were the basis for acouple of the completed Zhaga specifications.Remember that Zhaga’s process is based onmerging proposals from multiple companies.When asked if individual companieswere behind any of the Zhaga specifications,Treffers said, “In all cases there were multiplecompanies involved.” Still it’s pretty clearthat in some cases a single company has providedthe majority of the technical input.For example, photos that Zhaga has publishedmake it clear that the socketableLED light engine with separate controlgear is essentially GE’s Infusion module.And the LED spotlight engine with sep-More than your expectationYour partner for high efficiency SMD LEDExhibition:8-11th Nov. 2011,INTERLIGHT 2011(Russia),Booth T12.1 in Hall 7.1Luminous Efficiency :120lm/W ZERO degradation in 5,000 hours.__________Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM qMM MQmags| Next Page q qTHE WORLD’S NEWSSTAND ®

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM | Next PageqqM qMMQmagsTHE WORLD’S NEWSSTAND ®lighting | MODULES AND STANDARDSThe Westport tracklight on the left usesthe fi rst-generation Bridgelux/MolexHelieon module mounted in the trackhead and requires the separaterectangular driver mounted on thetrack arm. The reference design onthe right uses the new AC-poweredHelieon module that’s installed inthe track head and eliminates theneed for the external driver.arate control gear is Phillips’Fortimo SLM (spot light module)module. While the companiescan’t yet claim compliance,they have both said thatthe products are designed toultimately be compatible withZhaga specifications.Given the clear tie betweenInfusion and one of Zhaga’scompleted specific a t i o n s ,w ea s k e dSteve Briggs, vicepresident of marketingand productmanagementat GE Lighting Solutions(the LED-focusedbusiness within GE Lighting) about the collaborationin the Zhaga process. Briggs saidthat multiple companies were involved inproposing concepts and added “Our Infusionmodule has been shaped and changedby the Zhaga process.”As an example Briggs pointed out adesign change that happened between theannouncement of the second-generationInfusion back at Lightfair in May and theproduction modules that just commencedshipping in Q3. The mechanical design nowincludes mechanical mounting tabs on thefront of the module that allow easy connectionof reflectors or other optics.So in some cases the multiple parties thatparticipate in the Zhaga proposal-merger processmay have interest in different elements ofa luminaire design as opposed to being companieswith competing module concepts. Forexample, Posselt said that while Bridgelux is aZhaga member, that the company’s primarygoal in the endeavor is to “make sure our coreproduct, the LED array, is not precluded fromuse in Zhaga-compliant products.”Too many or just right?The question that arises with the ZhagaWhen it comes to lighting technology,nothing protects like Parylene.LEDs require superior protection to ensure reliable operation and long performance as lightingtechnologies in the aerospace, automotive, electronics, medical and military industriescontinue to advance.SCS Parylenes can be applied to virtually any surface material to create an ultra-thin, pinhole-free,conformal coating with superior moisture, chemical and dielectric barrier properties. Additionally,SCS Parylene coatings are optically clear, so the coating does not reduce the color or lumens outputof LEDs. As electronic packages are exposed to extreme environments, SCS Parylene HT® offerslong-term UV and thermal stability (up to 450°C), higher than most industry standard coatings.Contact SCS for more information about our innovative solutions for your LED technologies.World Headquarters (US): 317.244.1200Europe: 44.1483.541000Japan: 81.426.31.8680Singapore: 65.6862.8687www.scscoatings.com/LEDLEDsmagazine.com NOVEMBER/DECEMBER 2011 47Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM qMM MQmags| Next Page q qTHE WORLD’S NEWSSTAND ®

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM | Next PageqqM qMMQmagsTHE WORLD’S NEWSSTAND ®lighting | MODULES AND STANDARDS________________________progress to date is one of how many standardsdo we need. In lighting, there areclearly different requirements for modulesin different applications. For examplestreet lights will need larger modules withspace for more LEDs. Downlights and spotlights will need small circular modules andlinear fixtures long and slim modules. Stillit’s already evident that Zhaga will publishspecifications that overlap and that may bebad for an industry looking for standardizationto ramp production volumes of interchangeableproducts.The opposite pull of the desire for standardizationand the need for optimum luminairedesign for a specific application is atough conundrum. Companies have vastlydifferent philosophies and that is surelyplaying out within Zhaga. To understand thephilosophical extremes, let’s take a closerlook at the existing module products availablefrom GE and Philips.Philips’ approach is a module for everyapplication or maybe more than one.Andrew Lindstrom, director of SSL at PhilipsLighting, said, “We have competing linesacross the board.” Consider street lightingwhere we have published numerous storiesabout applications that use Philips’ LEDginemodule (http://www.ledsmagazine.com/news/8/9/10). That module uses LEDsin an array with TIR (total internal reflection)optics on each LED to form a beam.Philips also offers the Fortimo LLM (linearlight module) that is based on remotephosphortechnology (www.ledsmagazine.com/news/8/5/2) and that targets outdoorapplications with output ranging from 1100-4500 lm. And the company has the FortimoHBM (high brightness module) thatuses phosphor-converted LEDs and delivers4000-6000 lm, and that Philips businessdevelopment manager Dan Sullivan saidis designed to be compatible with a Zhagastandard currently under development.In the indoor space the Philips line isequally if not more crowded. The FortimoDLM (down light module) uses remote phosphortechnology. Philips’ Sullivan said in arecent presentation that the remote-phosphorapproach could provide a 30-40% efficiencyadvantage. Philips’ Lindstrom addsthat the remote phosphor provides moreconsistent color and said “For the near term,12-18 months, remote phosphor is definitelygoing to be the way to go.”It’s worth noting that Zhaga doesn’t weighin on the choice of remote phosphor or directlighting using phosphor converted LEDs.Either is allowed although some mechanicaldesigns may lack the depth and size foran efficient mixing chamber needed for theremote approach.Moreover some applications aren’t compatiblewith remote phosphor even if it doesoffer an efficiency advantage. Philips forinstance, uses phosphor-converted LEDsin the aforementioned Fortimo SLM. Lindstromsaid the need for a tight beam patterndictated the choice.One module, many usesGE, conversely is planning to use Infusionacross applications. That usage certainlywon’t include street lights. Briggs said thatthe company is investigating linear modulesfor such applications. But Infusion willspan downlights, spot lights and many otherindoor products. GE has announced Infusionmodules ranging in output from 850-3500 lmand plans to go to 5000 lm.Briggs said that luminaire makers will beable to choose a module with an LED packagethat’s optimum for any specific application.They will add an optics package that’smatched to the LED package and application.GE already has a broad portfolio of optics andthird parties will offer products as well.The migration to modules is in the earlystages. It’s too soon to know if modules willbecome the dominant choice for SSL implementationsor remain a niche. Much maydepend on how well Zhaga is accepted. Evenif Zhaga yields overlapping specifications,the standardization effort does accomplishsomething else – it opens technology developedwithin companies to others. No one hasrights to the intellectual property within aGE Infusion module, for example, but otherscan build compatible products once Zhagapublishes the specification.And modules are being successfully – andspectacularly – deployed today. Our coverphoto for this issue, and another nearbyphoto, are of the Dusseldorf parliament halllit by Hoffmeister Leuchten LED downlightsthat are based on 2000-lm Philips FortimoDLM modules.48 NOVEMBER/DECEMBER 2011 LEDsmagazine.comazine.comPrevious Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM qMM MQmags| Next Page q qTHE WORLD’S NEWSSTAND ®

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM | Next PageqqM qMMQmagsTHE WORLD’S NEWSSTAND ®________________Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM qMM MQmags| Next Page q qTHE WORLD’S NEWSSTAND ®

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM | Next PageqqM qMMQmagsTHE WORLD’S NEWSSTAND ®_____________________________________________________________Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM qMM MQmags| Next Page q qTHE WORLD’S NEWSSTAND ®

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM | Next PageqqM qMMQmagsTHE WORLD’S NEWSSTAND ®national focus | CHINALED revolution advances in Chinawith government backingDespite some quality issues, China now leads the world in the deployment of LED street lights, andthe country’s next Five-Year Plan is expected to drive further advancements, writes PHILIP JESSUP.China is the epicenter of the LED revolution,accounting globally for 46%of the consumption of high-brightnessLEDs in 2009, followed by North Americaat 30% and Europe at 17%, according toStrategies Unlimited. With over 2,200 manufacturersmaking LED devices, packages andluminaires today, China is advancing rapidlyto the forefront of Asia’s LED market.Although much of the country’s LEDindustry makes contract products for westerncompanies, the central and provincialgovernments, especially Guangdong Province,are aggressively developing their owninternal markets for high-quality, highbrightness,white-lighting applications.21 City, 10,000 LED Lights programIn 2009, the Ministry of Science andTechnology launched its “21 City, 10,000 LEDLights” program, the first phase of a muchlarger national demonstration project toinstall two million LED lamps in 50 cities.A key aim of the project is to enable LEDcompanies to deploy their LED products inthe cities where they are located, using largeinstallations as platforms for demonstration,for local investment, and to attract utilityorders. As a result, the Ministry providedsubsidies directly to the LED manufacturers– a 10% subsidy has been the norm – whichthen partnered with their local municipalgovernments. Here are some typical projects:Tianjin: A variety of outdoor LED demonstrationprojects were undertaken in 2010on the Tianjin Polytechnic University campus(see photo) and on the city’s streets, aswell as many indoor installations, totalingPhoto courtesy of Ryan Pyle.110,000 lighting fixtures.Hangzhou, Zhejiang province: An outdoordemonstration was undertaken of LEDluminaires along 21 km of the Jinghang orGrand Canal and in the vicinity of WestLake. A total of 65,000 outdoor and indoorLED lamps were installed.Dongguan, Guangdong province:Demonstration of 20,000 LED street lightson a variety of streets, supplied by local firmKingsun Optoelectronic, one of China’s oldestLED product manufacturers.Shanghai: Support for LED street-lightdemonstrations at the Shanghai World ExpoPHILIP JESSUP is a Senior Advisor to The Climate Group and to its global LightSavers initiative(www.theclimategroup.com/lightsavers). The Climate Group’s Beijing staff provided research forthis article. See Jessup's article on India at www.ledsmagazine.com/features/8/10/5.This very long street on the Tianjin Polytechnical University campus in China is lit withhundreds of LED luminaires as part of a demonstration project.site, including the China Pavilion and a widevariety of streets near the Expo, as well aspublic spaces and landscape applications.Shenzhen, Guangdong province: Installationof 10,000 LED luminaires along 130 kmof expressway and tunnels, one of the largesthighway LED retrofit projects in China (www. ___ledsmagazine.com/news/8/10/13).The “21 City, 10,000 LED Lights” projectwas reportedly hampered by LED product-qualityissues. Failure rates of 70% andannual lumen depreciation as high as 30%in some locales have been reported anecdotally.Hence, the project slowed in 2011 toallow time for evaluation by the China Solid-State Lighting Alliance (CSA). Key problemsidentified by the CSA’s study were:• Municipal governments found it difficultLEDsmagazine.com NOVEMBER/DECEMBER 2011 51Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM qMM MQmags| Next Page q qTHE WORLD’S NEWSSTAND ®

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM | Next PageqqM qMMQmagsTHE WORLD’S NEWSSTAND ®national focus | CHINAto implement the programs. Financial subsidiesfrom central government were low,and restricted to the LED companies.• Technical assessment of the productsoffered by local companies and site applicationswas often insufficient, leading toa mismatch between the product and itsapplication.• Quality standards, LED procurement specifications,and project management processeswere lacking. National LED lightingstandards were still in development whenthe program unfolded.• Business modeling was challenging, due tounderestimated maintenance costs associatedwith non-standardized products andextensive product failures.• Low electricity prices and high LED costsextended payback periods under idealconditions to eight years or more in manycities.• A dearth of energy-service companies inChina with strong financial expertise in_______________energy-efficiency technologies made it difficultfor municipal governments to raiseadequate funding.• Regional trade-protection barriers withinChina prevented quality products frombeing used in many cities.Major recommendations coming out ofCSA’s review included creating nationalLED evaluation criteria; setting up quality-controlsystems; providing central-governmentsubsidies to local governments;implementing better coordination amongcentral government’s agencies; improvingLED manufacturing processes; and supportingfurther R&D. After the review, theMinistry expanded the program to a secondgroup of 16 cities in 2011.Guangdong leadershipDespite the early problems encountered,demonstration projects undertaken by citiesin Guangdong province proved very successful.This was due to the implementationof rigorous technical requirements and standardsassociated with the energy managementcontract (EMC) business model pioneeredin China by these cities.Under the EMC model, banks provideproject financing to the cities to coverthird-party testing data, feasibility analysis,street reconstruction, and light sources.The loans are repaid from energy savingsover a six-year period, which involves periodicfield monitoring. Typically, 10% ofthe project cost is subsidized by Guangdongprovince, 15% by the municipal government,and the remaining 75% financedthrough the EMC with an energy-servicecompany.Guangdong’s leadership in LEDs is drivenby the importance of the technology to theprovince’s economy. Companies located inthe province supplied 70% of China’s LEDpackages in 2010, with foreign investmentapproaching $1.5 billion in local LED firms,much of it centered in Shenzhen’s SpecialEconomic Zone.In order to maintain this momentum,Guangdong relies on aggregating local procurementto expand the provincial marketfor locally-produced LED luminaire products.As of the end of 2011, 200,000 streetlightluminaires had been installed on2,000 km of provincial streets and roads,including 100,000 units in the capital,Guangzhou (see also page 8). Installationof another three million LED street lightsis planned soon.In part due to the “21 City, 10,000 LEDLights” project and Guangdong’s leadership,China now leads the world in thedeployment of LED street lights. In 2010,approximately 350,000 LED street lightswere installed in Chinese cities, 74% of theglobal total, according to Strategies Unlimited.A temporary contraction is expectedin 2011.12th Five-Year Plan (2012-2016)China will continue its ambitious LEDlighting program in the next Five-Year Plan,which ambitiously aims for LEDs to achieve30% market share of China’s general lightingmarket by 2015. Guangdong provincehas adopted probably the most ambitiousprovincial goal: the installation of 30 millionindoor LED lights by 2015. Key elementsof the national plan include:• Continued R&D, industry promotion,and scale-up of niche applications suchas street lighting, tunnel lighting, andindoor uses.• Establishment of national photonic testinglabs in various regions, includingGuangdong.• Development of Chinese technology in thefield of metal-organic vapor-phase epitaxy(MOCVD).• Inclusion of LED domestic lamps in thecentral government’s Green Lights program,which offers substantial subsidiesin the A-lamp mass market.While quality issues have dogged China’sHB-LED efforts to date, these are notlikely to dampen the country’s long-termambition to become one of the top threeleaders in manufacturing LED products.It is expected that Chinese governmentswill effectively address LED product qualityproblems all along the supply chainthrough home-grown R&D and procurementinitiatives, and joint ventures withwestern LED companies such as Cree,while deploying a mix of well-coordinatedpolicies, subsidies, and market aggregationinitiatives that capitalize on the largesize of China’s market to gain comparativeadvantage globally.52 NOVEMBER/DECEMBER 2011 LEDsmagazine.comPrevious Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM qMM MQmags| Next Page q qTHE WORLD’S NEWSSTAND ®

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM | Next PageqqM qMMQmagsTHE WORLD’S NEWSSTAND ®Real parts. Really fast.Simply upload your 3D CADmodel, and get your lightingand LED parts fast.Injection Molding in 1–15 days.Best for 10–10,000+ parts.Priced from $1495.CNC Machining in 1–3 days.Best for 1–10 parts.Priced from $95.Choose from30 differentmaterialsincluding ABS,Nylon, PC, Delrin,PEEK, ULTEM,and aluminum.Choose fromhundreds ofengineeringgraderesins,including HDPE,Polypropylene,ABS/PC,Acetal, PBT,Polycarbonate,Nylon 66,Polyamideand LPDE.acrylic lighting componentIt’s easy to work withProto Labs.Choose CNC machining or injectionmolding, whichever is best for yourproject. Upload your CAD model andreceive an automated, interactivequote in hours. Once approved, ourcluster computing technology andautomated manufacturing systemswill deliver real parts using realmaterials in as little as one day.That’s the real story.aluminum heat sinkCheck out ourvideo design tips!©2011 Proto Labs, Inc. ISO 9001:2008 CertifiedGet Your ProtogamiOur newest design aid is a cool kaleidocyclethat shows the effect of materials on finishes.Visit www.protolabs.com/parts today andrequest your free Protogami! Enter code LM11C.Call 877.479.3680 or visit www.protolabs.comPrevious Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM qMM MQmags| Next Page q qTHE WORLD’S NEWSSTAND ®

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM | Next PageqqM qMMQmagsTHE WORLD’S NEWSSTAND ®_________________________________Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM qMM MQmags| Next Page q qTHE WORLD’S NEWSSTAND ®

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM | Next PageqqM qMMQmagsTHE WORLD’S NEWSSTAND ®conferences | STRATEGIES IN LIGHT 2012Strategies in Light 2012 to highlightLED market dynamicsWith the theme of “Navigating the Dynamic LED and Lighting Markets,” the 13 th annual Strategies inLight conference will be held in Santa Clara, California, on February 7-9, 2012 writes BOB STEELE.www.strategiesinlight.comIt can be said with some certainty that2011 is shaping up as one of the most challengingyears in the history of the HB-LEDindustry. After an astounding 108% marketgrowth in 2010, driven largely by the adoptionof LED backlights in LCD TVs, computermonitors and notebook computers, themarket is expected to grow at a rate ofless than 10% in 2011 (ledsmagazine. _________com/news/8/10/9). Demand for LCDTVs has slowed, and the oversupplyof LEDs caused by widespread capacityexpansion has put strong downwardpressure on prices. Helping conferenceattendees to understand the dynamicsof this rapidly changing and complex marketis a key goal of Strategies in Light 2012.To address the wide range of issues andgrowing pains facing the LED industry,Strategies in Light 2012 has assembled a rosterof distinguished speakers from all levelsof the LED and lighting supply chain, andfrom all parts of the globe. As usual, the conferencewill be kicked off by a presentation ofStrategies Unlimited’s most recent researchupdate and forecast for the worldwide HB-LED market, delivered by Ella Shum, Directorof LED Market Research.Headlining the conference’s Plenary Sessionwill be Ling Wu, General Secretary ofthe China Solid-State Lighting Association.With the expansion of the LED industry inChina much in the news this year, Ms. Wuwill shed light on the future developmentstrategies of China’s SSL industry. Koreahas been a key player in the recent growthof the LED market, and C.H. Lee, CEO ofSeoul Semiconductor, Korea’s largest independentLED supplier, will provide hiscompany’s perspective on the LED industry’strajectory. The final Keynote Speaker,Eric Kim, is CEO of Soraa, Inc., the startupco-founded by LED industry legend ShujiNakamura. After many months of beingin “stealth mode” regarding its technology,Mr. Kim will discuss Soraa’s holisticapproach to LED lighting.Following the opening Plenary Session,SIL 2012 will split into three paralleltracks – the traditional HB-LED Marketand LEDs in Lighting tracks, plus an LEDManufacturing track, new for 2012. Leadingoff the LEDs in Lighting track, StrategiesUnlimited’s Director of LED LightingResearch, Vrinda Bhandarkar, will providean update and forecast of the LEDluminaire and replacement lamp markets.The first keynote speaker will be veteranlighting designer Ted Ferreira, Principalat CD+M Lighting Design Group, who willaddress the issue of sustainable design asit relates to the SSL industry. Dave Ranieri,VP and General Manager of the CommercialIndoor Business Unit, Lithonia Lighting,will discuss the advent of intelligentdigital lighting.The lead keynote speaker for the LEDManufacturing track will be Iain Black, VPof Worldwide Manufacturing, Engineeringand Innovation for Philips Lumileds Lighting,who will address the manufacturingchallenges of dealing with complexity in anevolving market. He will be followed by TomMorrow, Executive VP of SEMI, who will discussthe issues associated with the recentunprecedented expansion of LED manufacturingcapacity around the world. JacobTarn, President of TSMC Solid-State LightingLtd., will provide insight on whether a majorsemiconductor company can help to acceleratethe LED cost-reduction curve.Other speakers in the HB-LED Markettrack will address topics ranging from providingLED-based lighting to the rural poor,to the market for LED backlights in displays,automotive headlamps, LED lighting,and strategies for dealing with thecurrent tumultuous LED market. Twopanel sessions will be offered – oneon new developments in phosphors(including quantum dots) and one ondrivers, controls and dimming.In the LEDs in Lighting track, presentationswill address lighting in the retailindustry, utility energy-efficiency programs,the results of DOE’s Caliper testing ofLED replacement lamps, museum lighting,“smart” street lighting, and the digital controlof lighting, among many other topics.The LEDs in Manufacturing track willfocus on the issues faced by the LED industryas it scales up to unprecedented levelsof high-volume production. Topics tobe addressed will include the developmentand application of new equipment and techniquesto move to larger substrate sizes,increase automation, improve yield andthroughput, and provide lower cost andmore robust packaging.In addition to the three main conferencetracks, Strategies in Light 2012 will continueits tradition of offering a full-day Solid-StateLighting Investor Forum, featuring presentationsby a wide range of advanced technologystart-ups. Moreover, five in-depthworkshops and two lighting tutorials will beoffered on the day before the main conference,along with numerous informative freepresentations in the LED Light and DesignPavilion on the exhibit floor.LEDsmagazine.com NOVEMBER/DECEMBER 2011 55Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM qMM MQmags| Next Page q qTHE WORLD’S NEWSSTAND ®

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM | Next PageqqM qMMQmagsTHE WORLD’S NEWSSTAND ®Products TRPSupplies to OEMsLED CoreIntegrated Light Engine, Opticsand Thermal Management DesignPutting It All TogetherFor You:INTEGRATEDLED System SolutionsLED DriversConstant-current, constant-voltage,custom outputs, and multi-channelThomas Research Products capitalizes on ourexperience in driver design to offer you the mostcost-effective solution by maximizing efficienciesof the Driver and LED Core with an emphasis onefficiency, optical and thermal performance.TransformersStep-down and step-up modelsenable fixtures to operate on anysystem voltageSurge ProtectorsANSI C62.41.2 compliant to protectfixtures from high-voltageline transientsNew20 kAModel11548 Smith Dr. Huntley, IL 60142LEDsystems@ThomasResearchProducts.comwww.thomasresearchproducts.comPrevious Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM qMM MQmags| Next Page q qTHE WORLD’S NEWSSTAND ®

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM | Next PageqqM qMMQmagsTHE WORLD’S NEWSSTAND ®strategically speaking | DRIVER MARKETLED drivers represent a criticalbut confusing marketThe LED driver market is characterized by complex and dynamic design issues, volatile pricing,varying degrees of integration and customization, and confusing terminology. TOM HAUSKEN makessense of it all.With all the attention devotedto LEDs and LED lighting, youhear surprisingly little aboutthe rest of the electronics in LED products— what is known as the driver. Yet,the driver design determines such thingsas whether the product is properly loadedor inefficient, or whether the LEDs have tobe tightly selected or can be loosely binned.And if you think that driver design is wellunderstood and mature, you are wrong, forreasons that this article will discuss. Driverdesign is evolving rapidly to keep up withnew applications and new requirements,such as improved power factor correctionand sophisticated dimming for improveduniformity and reliability.Driver IC market scales with LEDsLet’s make one thing clear: the market forLED driver ICs – an important component ofmost LED drivers – is significant, at $2 billion.Also, it’s growing at about the same rateas the LED market, about 13% per year (Fig. 1).Most LED driver ICs are used in backlightsfor LCD displays, such as in mobile phonesand TVs. These are dynamic consumer endproducts, with short product cycles and tightcontrol on performance, size, and cost. Thatmakes the driver-IC segment dynamic too.The next big opportunity in LED drivers isin LED lighting. There have been LED lightingproducts in the market for many years,but in niche categories like architecturalTOM HAUSKEN is Director of the ComponentsPractice at Strategies Unlimited, a marketresearch firm based in Mountain View,California (www.strategies-u.com). Thecompany’s most recent market-research reporton LED Driver ICs was published in June 2011.Revenue ($ Billion)4.03.53.02.52.01.51.00.50.02010 2011 2012 2013 2014 2015lighting, exit signs, and flashlights. Now,LED replacement bulbs are being sold inhardware stores, with the promise of largevolumesales but extreme demands are beingmade on size, efficiency, and cost. After thatwill come growth in general commercialand industrial luminaires, as building ownerschoose LED lighting for the lower-lifecyclecost compared to legacy lighting. Theresidential segment will take longer becauseprivate homeowners donate their labor forbulb replacement and do not strictly rationalizetheir life-cycle costs.The driver is important, but it’s underappreciatedby the industry and difficultto forecast. Why is that? The following sectionsexplain.1. Confusing terminologyOne reason is that the terminology isabsurdly confusing, although it can bemastered with a few pointers. Most important,the driver is the entire circuit, minusthe LEDs. A driver IC is one or more ICs dedicatedto controlling the current, and sometimesalso the voltage, in the driver circuit.Fig. 2 shows an example of each. Nearly everyLED-based light has a driver, even a simpleone, but not every driver has a driver IC.SignsVehiclesLightingTVs and monitorsMobile appliancesFIG. 1. Revenue growth for LED driver ICs tracks the growth in the HB-LED market. Thestrongest sales today are in backlights for displays in mobile appliances and TVs, butLED lighting is becoming the next big thing (source: Strategies Unlimited).The term controller refers to a circuit withinthe driver that controls the LED current. Weuse microcontroller to refer to programmableboxes added by the lighting designer or customerto manage the system (for example, atimer or dimmer switch). This is shown in Fig.3, in which the current controller is a key partof the driver, but the programmable microcontrolleris entirely separate.2. Complex, unique, dynamic designDriver design is not simple and standardizedas many people assume. First, LEDs requireLEDsmagazine.com NOVEMBER/DECEMBER 2011 57Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM qMM MQmags| Next Page q qTHE WORLD’S NEWSSTAND ®

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM | Next PageqqM qMMQmagsTHE WORLD’S NEWSSTAND ®strategically speaking | DRIVER MARKETconstant, high-current sources, which areunusual in electronics and create unusualchallenges for product engineers. Moreover,the designs are complex and unique to everyLED product. The end-product features areconstantly evolving: from keypads to touchscreens,from one type of edge-lighting toanother, and so forth. And, there is a wide varietyof supply arrangements that obscure thelandscape for observers: from conventionalsuppliers to contract manufacturers to widespreaduse of chip foundries to manufacturersof custom ICs for specialized driver designs.Fig. 4 shows some examples of LED drivercircuits driven from a DC voltage. Thestrings of LEDs, shown in the figure as singlediodes, require at least some current control.A common design uses only a resistor tolimit the current (Fig. 4a). This approach issimple and inexpensive, and is common invehicle lighting, but is inadequate for applicationsdemanding precise control and uniformity,such as backlights or signs. Substitutinga linear regulator (not shown) for thecurrent-limiting resistor improves the currentcontrol. Ganging multiple regulators inparallel into an IC can reduce the componentcount and improve reliability (Fig. 4b).Controlling the input rail voltage is normallyconsidered the task of the system’spower supply, but many LED applicationsrequire a voltage conversion to match theLED load. An IC may be dedicated for thatpurpose (Fig. 4c). For example, LED backlightscan operate with strings of up to 10 ormore LEDs in series, with a total string voltageof 60V or more.FIG. 2. An LED driveris the electrical circuit,minus the LEDs. The drivermay include one or more driver ICs,or none. The driver at left from ROALElectronics and the driver IC at right fromTI both serve LED lighting.3. IC integration and customizationVoltage conversion creates another option: theconverter IC may be combined with a currentregulatingfunction on the same chip (Fig. 4d).The choice to integrate voltage conversionand current regulation depends on many factors,such as the need for reduced componentcount, current requirements, and so forth.LED driver ICs are especially vexingbecause of the ways that multiple functionsor components can be integrated onto onechip. For example, in a handset the LED flashand backlight functions can be managedwith multiple ICs, or they can be integratedinto a single IC, or they can be managed withyet other handset functions in a general-purpose-power-managementIC (PMIC). We considera PMIC to be in a category apart, not anLED driver IC, if it includes management ofbattery recharging and voltage regulationfor other functions. The trend toward PMICstherefore shifts some of the sales of LED driverICs to suppliers of PMICs.The trend toward integration also offersan opportunity for chipmakers that useBCD (bipolar-CMOS-DMOS)processes to fabricate LEDdriver ICs that enable highvoltageoperation. BCD allowsfor integration of diverse circuitelements – such as lowvoltageanalog and high-voltagepower transistors – on thesame chip. It is a high-margingrowth opportunity for thefoundries and chip suppliersthat can do it.Customers must alsochoose between customASICs (application-specificICs) that form a perfect fitfor their application versusoff-the-shelf products thatleverage non-recurring engineeringcosts. Customerscommonly veer between custom and standardproducts depending on many changingdemands in their product cycles.4. Potentially disruptive AC-LEDsNovel AC-LED products have the potentialto complicate the driver market. Inits purest form, the AC-LED eliminatesthe driver, using the diode features of theLED to replace conventional diodes. Otherdesigns use some basic components to limitthe current, but sparingly. If highly successful,the AC-LED could make some LED lightingproducts – such as replacement bulbs– more competitive and greatly expand theLED-lighting market. Such a move could begood for both the LED industry and the endDriverVoltageconverter(External)programmablemicrocontrollerLED(Integrated)current controllerFIG. 3. The driver (dotted rectangle) in this simplifi edcircuit includes a voltage converter and a currentcontrollingelement. The programmable microcontrolleris not part of the driver. It is external to the LEDproduct, and may include such features as timing,dimming, and color control.users, but would displace potential driversales for those products.However, we expect that AC-LEDs will havean impact only in certain product segments.In replacement bulbs, the pressure to innovateis so high that the AC-LED is just one of severalnovel solutions, and there is no room forolder, less-innovative designs. Consequently,58 NOVEMBER/DECEMBER 2011 LEDsmagazine.comPrevious Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM qMM MQmags| Next Page q qTHE WORLD’S NEWSSTAND ®

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM | Next PageqqM qMMQmagsTHE WORLD’S NEWSSTAND ®strategically speaking | DRIVER MARKETa) b)Current-limitingresistord) c)+–+–VoltageconverterandcurrentcontrollerICthere are plenty of opportunities for everyone.The high-voltage LED (HV-LED) is anotherbuzz word but it will have minimal impacton the driver market. LED-based productscommonly use long strings of LEDs in series.Until recently, the LEDs have been packagedin discrete packages and assembled together+–+–VoltageconverterICCurrent controller ICCurrent controller ICFIG. 4. LED driver design ranges from minimal (the current-limiting resistor) tomonolithic integration of multiple channels and even voltage conversion onto a singledriver IC, with the specifi c design unique to each product and application. Strings ofLEDs are represented in the fi gures as single diodes.in the luminaire or lamp. An HV-LED integratesthe LED string onto the same chipor within the same package, gaining someadvantages for the customer. It means littleto the driver design, other than the usualconsiderations for the LED load that impactsevery product design.5. Volatile pricingEstimates for IC pricing also complicate theforecast. It’s obvious that IC prices declineover time as volumes increase and marginsshrink. What’s not as clear is the effect onthe average price of changes in the productmix. New products can appear at muchhigher prices than more-mature productsin the same category, but can earn the differencevia savings in component count orimproved LED performance. The new productsmay be priced higher because they usea larger chip that takes up more wafer area,because they use a more expensive foundryprocess, or simply because they delivermore value, and can earn greater marginfor the chip supplier.Temporary oversupply or shortages ofproducts within the supply chain – suchas driver ICs, LEDs, or the end products –also create fluctuations in prices. We ignorethese short-term fluctuations; in our studieswe focus on the underlying mediumtermtrends in demand and technology.LEDs are relatively uniform and easy tounderstand – compared to drivers. As onesupplier said, explaining drivers requiresa deep dive, but few customers have thepatience or expertise to listen for very long.Yet, with some patience, LED drivers can beappreciated as a critical partner to LEDs,which garner so much attention.___________________LEDsmagazine.com NOVEMBER/DECEMBER 2011 59Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM qMM MQmags| Next Page q qTHE WORLD’S NEWSSTAND ®

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM | Next PageqqM qMMQmagsTHE WORLD’S NEWSSTAND ®____________________________________Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM qMM MQmags| Next Page q qTHE WORLD’S NEWSSTAND ®

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM | Next PageqqM qMMQmagsTHE WORLD’S NEWSSTAND ®lighting | PLANAR FIXTURESLED backlight technology offerspromising choice for lightingEdge-lit light guides with embedded optics can provide precise light control and high opticaleffi ciency in general-lighting applications, say JOHN LANGEVIN and KENDRA DE BERTI.JOHN LANGEVIN is the director of strategicdevelopment and KENDRA DE BERTI is asenior marketing manager with Rambus (www. ___rambus.com/lighting).Planar light fixtures offer aestheticadvantages in many applicationsand the inherently-diffused conceptcan efficiently deliver the required light toa task plane. The potential market for suchfixtures has driven the solid-state lighting(SSL) industry to pursue several approachesto planar lighting including OLEDs andpanels that are edge- or back-lit by LEDs.Technology with an LCD-panel backlightunit (BLU) heritage can enable planar fixturesand may prove the best option in suchluminaires in terms of light control andapplication efficiency.In general, the introduction of LEDs tothe application of general lighting presentslighting architects and fixture designerswith unprecedented flexibility that can'tbe achieved with the constraints of bulbsand tubes. LEDs can slash energy use andoffer greater control and directionality oflight. Moreover, the light source can nowbecome an integrated part of the fixtureitself rather than a replaceable object to bedesigned around.In the BLU segment, meanwhile, thegrowing popularity of LEDs has driveninnovations in the LEDs themselves, andhas yielded new LED subsystems in theBLU that control and distribute the light.These subsystems include advanced opticsthat enable precise control of the uniformityand emission angle of light out of theBLU, while helping maximize the amountof light delivered through the LCD panel.With shared needs for lower power andcost, longer lifetimes, improved color qualityand the desire to eliminate light sourcesthat contain hazardous materials, the lightingindustry can benefit from the advancesof LED backlighting in the display industry.The proven technologies originally implementedin display backlights can be leveragedto accelerate the time-to-market andadoption of LED-based light fixtures.Direct-view fixture Indirect-view fixture Edge-lit fixtureFIG. 1. LED fi xtures can be direct- or indirect-view, or edge-lit.Thin is inBLUs can be edge- or direct-lit, with LEDsplaced on the sides or directly behind an opticallight guide. The lighting market has similaroptions for illumination. Today’s LED lightfixtures can be direct- or indirect-view, oredge-lit (Fig. 1). In a direct architecture, as thename would imply, the light source is in viewand aimed directly at the illumination target.Though seemingly the most efficient, the aestheticsof direct-lit fixtures can be unpleasant.Because of their luminous intensity, theLEDs in these direct-lit architectures createbright spots that are uncomfortable to lookat, so diffusers are often included to reduceglare. However, these diffusers reduce theoptical efficiency of the fixture.Indirect fixtures offer a softer aestheticby bouncing the light off a surface, such asa back reflector or a ceiling, before illuminatingthe desired area. While indirect fixturesavoid the glare drawbacks of direct-litarchitectures, they do so at the cost of efficiency.A portion of the light is lost throughabsorption by the surfaces used to reflectit, as well as that lost when propagated inundesired directions.A third alternative is the edge-lit architecturethat places LEDs along one ormore edges of a light guide whose principalfunction is to direct and distribute lightas desired. Light guides are typically madeof thermoplastics such as acrylic or polymethylmethacrylate(PMMA). Light emittedfrom the LEDs is directed into the edgeof the light guide and distributed throughoutusing the properties of total internalreflection (TIR). Different types of opticalelements that are printed, etched orembedded into the light guide are thenused to extract the light via the propertiesof refraction (Fig. 2).Forming optical elementsAll of these various patterning techniquesLEDsmagazine.com NOVEMBER/DECEMBER 2011 61Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM qMM MQmags| Next Page q qTHE WORLD’S NEWSSTAND ®

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM | Next PageqqM qMMQmagsTHE WORLD’S NEWSSTAND ®lighting | PLANAR FIXTURESfor edge-lit fixtures can produce good uniformity,but they have a wide range of opticalefficiencies, tooling costs, manufacturingcosts, and optical characteristics.Printed and chemically-etched dots offerlow-cost manufacturability, but producediffused light outputs that offer virtually nocontrol of the beam pattern. Laser-etchedoptical features provide improved opticalefficiency, but require long manufacturingcycle times. Light guides with embeddedoptics combine specular reflection withfast and highly-repeatable manufacturingto deliver the highest level of ray-angle controland lowest overall cost.One example of embedded optics is Rambus’MicroLens light-distribution technology.MicroLens optics are 3-dimensionalelements embedded directly into the lightguide using injection molding, extrusion,or hot-embossing processes. They producea highly-directed light output, provide rayanglecontrol, and maximize the amountof light delivered on target. In addition, thedistribution pattern can be customized tomeet specific application needs by varyingthe shape, size, location and densityof the optics.In many ways, edge-lit architectures combinethe benefits of direct and indirect fixtureswhile also providing unique benefits.They offer high optical efficiency, control ofthe light distribution, reduced number ofLEDs, and superior aesthetics. The adoptionof edge-lit BLUs has enabled sleek, ultrathinnotebook computers, tablets, monitorsand HDTVs that are less than 0.3 inchthick at a lower cost than direct-lit counterparts. Those same benefits can be leveragedfor lighting. Light guides with embeddedoptics can be implemented in countlessshapes and sizes with a wide variation oflight distribution patterns. Edge-lit fixtureswill usher in a new era of efficient, flexibleand beautiful products. But with these newcapabilities and flexibility of form factor,what is the best method for comparing relativeperformance and efficiency?Introducing a new metricWith the introduction of energy-efficientlight sources, such as fluorescents andLEDs, the reference to the wattage of a bulbis no longer an acceptable means of expressingthe light output. In an effort to ease theIn many ways, edge-lit architectures combinethe benefi ts of direct and indirect fi xtureswhile also providing unique benefi ts.PatterningtechnologyMethodOpticsOpticalefficiencyUniformityManufacturabilityPrinted dot Diffuse Good Good FastChemicaletch Diffuse Good Good FastFIG. 2. Optical elements can be formed in several ways.transition, the term "watt equivalent" hasbeen used to provide a reference. For example,a typical 60W incandescent bulb generatesabout 800 lm. But a 60W-equivalentLED bulb uses less than 12W to produce thesame amount of light. The use of lumens hasalso been incorporated to describe the luminousflux or light output of a light source.Luminous efficacy, measured in lumens-perwatt(lm/W), is an important metric whendescribing the efficiency of a light fixture,but it doesn’t tell the whole story.Lumen output provides an accurate representationof traditional light sources as it isan averaged value used to measure total lightoutput from an omnidirectional light source.However, LEDs are directional, so these metricsfail to accurately depict the true benefitsof LEDs as general light sources. By usinglumen output as a measurement for LEDbasedfixtures, the actual amount of light theluminaire is capable of delivering to a specificsurface can be misrepresented.Where all of these metrics miss the mark isthat they measure the amount of light emittedfrom a light fixture rather than the actualamount delivered to the desired applicationarea. The end goal of any lighting design isto create beautiful, functional spaces as efficientlyas possible. This is achieved throughthe uniform distribution of light to a desiredsurface, minimizing light lost in undesireddirections, and improving lighting ergonomicsthrough reduced glare.Application efficiencyIn order to truly maximize the amount oflight delivered to a desired area with theleast amount of energy required, designersmust focus on the application efficiencyof the fixture. Application efficiency is thepercentage of light delivered to the targetedarea as it relates to the total light output ofthe fixture. In other words, the amount oflight emitted from a fixture and directed toa specific surface. In order to achieve highapplication efficiency, a fixture must combinehigh luminous efficacy with the abilityto direct as much of the emitted light to thedesired surface, or area, as possible (Fig. 3.).Application efficiency depends on threeLaser etch Diffuse Better Better Slow Specular(ray angle control) Best Best FastEmbeddedoptics62 NOVEMBER/DECEMBER 2011 LEDsmagazine.comPrevious Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM qMM MQmags| Next Page q qTHE WORLD’S NEWSSTAND ®

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM | Next PageqqM qMMQmagsTHE WORLD’S NEWSSTAND ®lighting | PLANAR FIXTURESOptimizedLED-to-light-guideinterfaceCustom controlledlight outputMaximum lightextractedfrom light guideHigh opticalefficiency+ =Precise rayangle controlHighestapplication efficiencyFIG. 3. LEDs and ray control yield high application effi ciency.elements: the efficacy of the LEDs, the opticalefficiency of the total fixture, and thedegree of ray-angle control provided bythe fixture’s optics. Today’s high-brightnessLEDs deliver upwards of 140 lm/W,but not all of the light emitted from theLEDs is effectively delivered to the fixture.Special design techniques are requiredin order to maximize the efficiency of theinterface between the LED light source andthe light guide.There are additional losses introducedby the fixture inherent in the LED driverused to condition the power supplied tothe LEDs, the thermal-management systemused to cool the fixture, and the opticsused to extract light out of the fixture. Asystem-design approach which takes allof these elements into account is requiredto maximize the overall efficiency of thelight fixture.Finally, light emitted by the fixture inundesired directions is effectively lost. Theability to control the light delivered fromthe fixture to the desired area depends onthe nature of the optics used in the lightguide. While diffuse optics cannot directthe light in a specific direction, specularoptics embedded in the light guide, suchas MicroLens optics, can. As a result, morelight can be directed to the desired surface,with less light straying to an unneeded area.A system approachBy optimizing the LED efficacy, opticalefficiency, and driver design, and then providingray-angle control, fixture designerscan achieve maximum application efficiencyto reach their end goal of creating aproductive, functional space with the leastamount energy.In the display market, edge-lit architecturesare the leading way to employ LEDsfor BLUs. They deliver efficiency, thin displays,and low cost. Ultimately, these samebenefits will translate to edge-lit architecturesbecoming the preferred solutions forlighting. The added benefit of form-factorflexibility means edge-lit solutions offertremendous freedom of design. Lightingdesigners no longer need be constrainedby the limitations of legacy bulb and tubebasedfixtures. Nor should they evaluatelighting solutions only in terms of legacymeasures. By designing with maximumapplication efficiency in mind, they can createbeautiful, functional spaces with fewerfixtures and lower energy consumption._______________LEDsmagazine.com NOVEMBER/DECEMBER 2011 63Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM qMM MQmags| Next Page q qTHE WORLD’S NEWSSTAND ®

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM | Next PageqqM qMMQmagsTHE WORLD’S NEWSSTAND ®__________________Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM qMM MQmags| Next Page q qTHE WORLD’S NEWSSTAND ®

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM | Next PageqqM qMMQmagsTHE WORLD’S NEWSSTAND ®standards | OPTICAL SAFETYLED-based products must meetphotobiological safety standards: part 2The potentially complex procedure of evaluating LED photobiological safety is now a legalrequirement in Europe, but few countries have yet followed the European mandatory-testing lead.LESLIE LYONS discusses the implementation of the IEC62471 standard after an in-depth look at themeasurement of radiance and irradiance.Part one of this three-part series providedan overview of the potentialhazards to the human body posed byexposure to optical radiation, and the developmentof international standards to evaluatethe photobiological safety of non-lasersources (see LEDs Magazine October 2011,p31; ledsmagazine.com/features/8/10/8).Here, a more practical approach is adopted,in considering the finer details of source evaluationand the implementation of safety standardsin Europe and the rest of the world.Scope of IEC62471:2006The IEC62471:2006 standard “PhotobiologicalSafety of Lamps and Lamp Systems” providesguidance for the evaluation of the photobiologicalsafety of all electrically-powered,non-laser sources of optical radiationemitting in the spectral range 200-3000 nm,whether or not the emission of light is theprimary purpose of the product. The inclusionof LEDs in the scope of this standardis specifically mentioned to highlight theremoval of LEDs from the scope of the laserstandard, IEC60825.The potential hazards of exposure to theskin, the front surfaces of the eye (cornea,conjunctiva and lens) and the retina areevaluated through consideration of six specifichazards with respect to exposure limits(ELs) provided for an exposure durationof eight hours, taken as a working day. TheLESLIE LYONS is the Technical SupportManager with Bentham Instruments Ltd (www. ____________bentham.co.uk), Reading, UK. He is a member ofBSI and IEC committees including TC76, OpticalRadiation Safety and Laser Equipment.standard does notconsider the potentialeffects of longtermexposure,nor of abnormalphotosensitivity.In the case ofhazards to theskin and front surfacesof the eye,it is sufficient to FIG. 1. Defi nition of irradiance.take into accountthe amount of lightincident on the surfacein question.However, to considerhazards to thedAretina, one musttake account of theimaging propertiesof the eye. It followsthat two distinct FIG. 2. Defi nition of radiance.measurements arerequired: irradiance and radiance.The standard provides specific guidanceon the geometrical conditions under whichthese measurements should be made to takeinto account biophysical phenomena, such asthe effect of eye movements on retinal irradiation.The spectral range over which radianceshould be considered is reduced to 300-1400nm, since the retina is essentially protectedoutside this range due to the transmissioncharacteristics of the lens. Table 1 indicatesthe required measurement (radiance or irradiance)for different hazards.Measurement of irradianceIrradiance permits the evaluation of hazardsdΩθdϕdϕdAto the skin and front surfaces of the eye.Irradiance is defined as the ratio of radiantpower (dΦ) incident on an element of a surface,to the area (dA) of that element (Fig. 1).Its symbol is E and its units are W/m².Irradiance accounts for light arriving ata surface from the entire hemisphere above.However, due to its position with respect tothe bridge and nose, the eye is shielded fromwide-angle radiation. Within the scope ofthis standard, the measurement of irradiancein all but the case of the thermalskin hazard is performed over a 1.4-radianacceptance angle. Light emitted from asource outside this acceptance angle neednot be measured.LEDsmagazine.com NOVEMBER/DECEMBER 2011 65Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM qMM MQmags| Next Page q qTHE WORLD’S NEWSSTAND ®

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM | Next PageqqM qMMQmagsTHE WORLD’S NEWSSTAND ®standards | OPTICAL SAFETYIn measuring irradiance, the measurementoptic, typically a diffuser or an integratingsphere, should have a cosine angularresponse to correctly account for off-axiscontributions. At a given angle from the surfacenormal, the projected area on the surfaceis increased by the cosine of the saidangle, resulting in reduced irradiance.Knowledge of source irradiance doesnot however give any information aboutthe quantity of light coupled by the eye andimaged on the retina, for which a measurementof radiance is required.Measurement of radianceRadiance permits the evaluation of hazardsto the retina. Radiance is defined as the ratioof radiant power (dΦ) emitted by area dAinto solid angle dΩ at angle θ to the sourcenormal, to the product of solid angle dΩ andthe projected area dA∙cos θ (Fig. 2). The symbolis L and the units are W/m²sr.In viewing a source, the eye collectsSourceSourceFSolid angle, ΩγObject distance, S1Field stopγrAperture stop, DFIG. 3. Measurement of radiance: imaging technique.FIG. 4. Measurement of radiance: indirect technique.Image distance, S2γCosine correctedinput opticSkin & EyeRetinalight within a given solidangle set by the diameterof the pupil, and projectsan image of thesource onto the retina. Asthe pupil dilates (or contracts)according to thelevel of visual stimulus, orluminance, of the source,the retinal irradiance ofthe image increases (ordecreases).The law of conservationof radiance statesthat radiance cannot beincreased by passive opticalsystems such as the lens of the eye. Theretinal irradiance is therefore determinedfrom the source radiance and the solid anglesubtended by the pupil (2-7-mm diameter) atthe retina (17-mm distant) in the reverse ofthe determination of radiance from irradiance,given below.Imaged, Aperture(field stop)HazardWavelengthrange (nm)QuantitymeasuredActinic UV 200-400† IrradianceNear UV 315-400 IrradianceIR Radiation Eye 780-3000 IrradianceThermal Skin 380-3000 IrradianceBlue Light Small Source 300-700† IrradianceBlue Light 300-700† RadianceRetinal Thermal 380-1400† RadianceRetinal Thermal Weak Visual 780-1400† RadianceTABLE 1. Different hazards require the measurementof either irradiance or radiance. († Weighting functionrequired.)Radiance may be measured by two manners,either using an imaging technique orindirectly through an irradiance measurement.In both cases, the measurement is performedin a specific field of view (FOV) orsolid angle of acceptance (often described bya planar angle, θ) that defines the area of thesource measured.The imaging technique (Fig. 3) replicatesthe imaging of the eye. A telescope imagesthe source under test onto a plane at whichmay be placed apertures of varying diameterto select the required FOV of measurement.Alternatively, a measurement of irradiancewith a cosine-corrected input optic maybe performed (Fig. 4). An aperture is placeddirectly at the source to define the measurementFOV. The radiance is computed fromthe ratio of irradiance to the solid angle ofthe FOV in steradians.Physiological radianceFor momentary viewing , the retinal imageof a source subtends the same angle as doesthe source. The smallest image formed onthe retina, according to IEC62471, has anangular extent of 1.7 mrad, given the imperfectimaging performance of the eye.With increasing exposure time, due to eyemovement (saccades) and task-determinedmovement, the retinal image is smeared overa larger area of the retina, resulting in a correspondingreduction in retinal irradiance.A time-dependent function is defined to representthe spread of the retinal image in therange from 1.7 to 100 mrad. This covers therange from 0.25s (aversion response time) to10,000s exposure.66 NOVEMBER/DECEMBER 2011 LEDsmagazine.comPrevious Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM qMM MQmags| Next Page q qTHE WORLD’S NEWSSTAND ®

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM | Next PageqqM qMMQmagsTHE WORLD’S NEWSSTAND ®Adaptive lighting principle using a tunable condenser lensSecondaryopticsLEDAdaptivelensFWHM-angle45°> Apertures from 10 to 55mm,ideal for 500 to 4000 lumens> Excellent spot qualityfor all tuning states(no intensity rings as infixed lens shifting)FWHM-angle10°> Highest optical efficiency(low light loss)> Easy to motorizeManually tunablecondenser lensThe shape of our manuallytunable condenser lenscan be varied from flat tostrongly convex by rotatingan adjustment ringOptotune AG | Bernstrasse 388 | CH-8953 Dietikon | SwitzerlandPhone +41 58 856 3000 | www.optotune.com | info@optotune.comPrevious Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM qMM MQmags| Next Page q qTHE WORLD’S NEWSSTAND ®

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM | Next PageqqM qMMQmagsTHE WORLD’S NEWSSTAND ®standards | OPTICAL SAFETYIn the context of photobiological safety,the measurement of radiance is performedin a manner that reflects this phenomenoni.e. the FOV of measurement is chosen toaccount for the light falling within a givenarea of the retina. The measurement FOV followstherefore the same time dependence,from 1.7 to 100 mrad, regardless of the sizeof the source measured.The measured quantity is more accuratelytermed physiological radiance as opposed totrue radiance, which by definition samplesonly the emitting area of the source (Fig. 5).Where the physiological radiance is measuredin a FOV greater than the angle subtendedby the source, the resultant radianceis an average of the true source radianceand the dark background. Furthermore,since the angular subtense of a source varieswith distance, physiological radiance,unlike true radiance, is a function of measurementdistance.for household luminaires, but many metersfor street lighting, for example.Irradiance measurements may be performedat a convenient distance and scaledto 500 lux. However, physiological radiance,which depends on the source subtense withSpectral influenceIn the above, reference was made to irradianceand physiological radiance withno consideration for the spectrum of thesource, which is clearly very importantwithin the context of this standard. Thesequantities should, in practice, be evaluatedat each wavelength with a monochromator.This yields spectral irradiance and spectralphysiological radiance. The resultant spectrashould be weighted, where required,against hazard weighting functions to takeaccount of the strong wavelength dependenceof three of the hazards considered(Fig. 6). The result should be integrated overthe required wavelength range prior to comparisonwith ELs.Measurement distanceThe distance at which a source should beevaluated depends upon its intended application.Two exposure scenarios are considered;general lighting service (GLS) and allother applications (non-GLS).The present definition of GLS is ambiguous,but relates to finished products that emitwhite light and are intended for illuminatingspaces. Evaluation should be reported, notnecessarily measured, at a distance at whichthe source produces an illuminance of 500lux. This distance may be less than one meterFIG. 5. In each pair of images, the red circles show the measurement fi elds of view fortrue (left) and physiological (right) radiance. For true radiance measurements, thecircle encompasses only the light-emitting area, while the physiological radiance isan average of the true source radiance and the dark background.respect to the applicable FOV, should be performedat the correct distance.The rationale for the 500-lux condition isarbitrary and a bone of contention withinthe lighting industry since this in manycases does not represent a realistic exposurescenario. In the next part of this article,we shall consider how this issue is currentlybeing addressed.Non-GLS sources should be measuredat a distance of 200 mm from the (apparent)source. This distance represents thenear point of the human eye. At shorterdistances than 200 mm, the retinal imageis out of focus, resulting in lower retinalirradiance.Here, the concept of apparent source isimportant. Where a lens is used to collimatethe output of an LED, a magnified virtualimage is produced behind the chip. The200-mm measurement distance should betaken with respect to this apparent source,since it is this which the eye images.The measurement at 200 mm may representa worst-case exposure condition for theretina. However, this is not the case for theskin and front surfaces of the eye where theexposure distance may be closer. This lattereventuality has not yet been taken intoaccount in this standard, for which the primaryconcern is acute retinal damage.Comparison with ELsELs are provided in terms of radiant flux forthermal hazards or energy (radiant flux multipliedby time) for photochemical hazards:a measured irradiance result can be directlycompared with the former, and an exposuretime obtained for the latter. This proceduredoes not apply to the measurement of radiance,for which the FOV of measurement istime dependent.A pass/fail test is therefore applied to theretinal hazards based on measurements atFOVs corresponding to the minimum exposuretimes of the classification system inturn, starting from the exempt risk group.Where the resultant radiance exceeds themaximum-permissible radiance for a givenrisk group, the next risk group is tested.68 NOVEMBER/DECEMBER 2011 LEDsmagazine.comPrevious Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM qMM MQmags| Next Page q qTHE WORLD’S NEWSSTAND ®

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM | Next PageqqM qMMQmagsTHE WORLD’S NEWSSTAND ®standards | OPTICAL SAFETYThe detailed evaluation of retinal hazards israther more convoluted since source size andlevel of visual stimulus should be taken intoaccount in determining which ELs to apply.ClassificationAs outlined in part 1 of this article series,a classification system, based on the minimumexposure time before the EL isexceeded, is defined ranging from exempt(no risk) to risk group 3 (RG3; high risk).The limit irradiance (radiance) of each riskgroup can then be determined, and the measuredirradiance (radiance) may be comparedagainst these limits.LabelingIEC62471 is intended as a horizontal standard,and as such does not include manufacturingor user-safety requirements thatmay be required as a result of a productbeing assigned to a particular risk group.Relative efficacy (a.u.)1010.10.010.0010.0001200Actinic UV400Blue light600Such safety requirements vary accordingto application, and should be dealt with invertical, product-based standards. However,IEC TR 62471-2 does provide some furtherguidance on the measurement and providesa recommendation of labeling for each hazardand risk group (Fig. 7).Implementation of IEC62471 in EuropeIn the European Union, CE marking demonstratesproduct safety by compliance withthe relevant applicable EU directive, suchas the low-voltage directive (LVD), throughapplication of European Norme (EN) standardsharmonized to the directive underconsideration. While compliance with theseEN standards is not mandatory, it does providepresumption of compliance with theessential health and safety requirements ofthe directive considered.Optical radiation is specifically consideredunder the terms of the LVD. This isapplicable to electrical products operatingat voltages of 50-1000V AC. The Europeanadoption of IEC62471, namely EN62471:2008,is harmonized to the LVD.From September 1, 2011, evaluation ofLEDs against the laser standard (IEC60825)no longer allows presumption of conformitywith the essential health and safety requirementsof the LVD.From April 2010, the EU artificial opticalradiation directive (AORD), 2006/25/EC,came into force. This adopts exposure limitsslightly different to those of IEC62471.For consistency, EN62471 adopts the exposurelimits of the AORD and is the standardto be used to evaluate worker exposure toRetinal thermal800Wavelength (nm)FIG. 6. Hazard weighting functions used by IEC62471.100012001400non-laser sources of optical radiation.Also relevant to LEDs is the EU Toy Safetydirective, to which is harmonized EN62115“Safety of electric toys.” This standard hasin the past referenced the laser standard(EN60825) for the classification of LEDs. Itis currently under review, but it is expectedthat reference will be made to EN 62471where measurements are required.Finally, where products are not coveredby the LVD or toy directives, considerationshould also be made of the general productsafetydirective to which few standards arespecifically harmonized, yet for the evaluationof non-laser sources of light, EN62471 isthe relevant EN standard.Implementation of IEC62471 in ROWWhile many standardization bodies aroundthe world are considering the adoption ofIEC62471, few have yet issued nationalstandards let alone a legal framework torender testing mandatory. Of the activityRisk Group 2CAUTION. Possibly hazardousoptical radiation emitted fromthis product. Do not stare atoperating lamp. May beharmful to the eye.FIG. 7. Example label according to IEC TR62471-2.seen, much is related to the lighting industry,for which a well-defined standardizationframework is in place and under activedevelopment to accommodate solid-statelighting.To the knowledge of the author, China ispresently alone in having formally implementeda voluntary standard – GB/T 20145-2006 – with Japan expected to publish JIS C7550 in November 2011.Some countries, such as Australia andNew Zealand, are currently working onthe adoption of IEC62471 as a voluntarystandard. Another group (e.g. Hong Kong,Republic of Korea) are presently content toreference IEC62471 on a voluntary basis,while others (e.g. Canada) are at the stageof considering implementation and potentialregulations.Finally, in the US, where ANSI RP27.1exists as a voluntary standard, there is currentlyno mandatory requirement for theevaluation of non-laser sources. However,following a meeting in August 2011 of thestandards technical panel of UL/ANSI 8750“Light Emitting Diode (LED) Equipment forUse in Lighting Products,” a task group hasbeen formed to consider the implementationof photobiological safety standardsfor those lighting products covered by thisUL standard.Part 3 of this series of articles will discussthe implementation of IEC62471 to the LEDdevices of today, and its potential futuredevelopment. Also, it will be shown thatIEC62471 does not remain unknown to theworld, principally through the implementationof international IECEE CB and numerousother certification schemes.LEDsmagazine.com NOVEMBER/DECEMBER 2011 69Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM qMM MQmags| Next Page q qTHE WORLD’S NEWSSTAND ®

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeWe bring quality to light.qMqM | Next PageqqM qMMQmagsTHE WORLD’S NEWSSTAND ®LED test & measurementsolutions from the world leaderInstrument Systems continues to set the benchmark in LED metrology. Whether testing individual LEDs(standard or high-power), LED modules, or OLEDs - the global LED industry relies on us to engineer superiormeasurement equipment for high-speed production testing and high-performance R&D and QC applications.Our instruments provide accurateand reliable results as per CIErecommendations and methods: Luminous flux [lm], luminous intensity [cd],and luminance [cd/m2] Chromaticity coordinates x,y,z and u’v’ Color temperature and color rendering index Dominant wavelength and spectral data Spatial radiation patternInstrument Systems Germany · Phone: +49 89 45 49 43 0 · info@instrumentsystems.com · www.instrumentsystems.comPrevious Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM qMM MQmags| Next Page q qTHE WORLD’S NEWSSTAND ®

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM | Next PageqqM qMMQmagsTHE WORLD’S NEWSSTAND ®LED production | TESTINGProduction testing of HB-LEDs andLED modules demands the righthardware and techniquesCost-effective testing of LEDs and LED modules in a production environment can have a stronginfl uence on manufacturing effi ciency, as MARK CEJER explains.The latest high-brightness LEDs(HB-LEDs) offer ever-higher luminousflux, longer lifetimes, greaterchromaticity, and more lumens per watt. Toreduce the cost of LEDs to consumers, manufacturersare working to improve theiryields and their manufacturing-efficiencylevels. This requires cost-effective testingof LEDs and modules in a production environment.The key is to find the right combinationof test equipment and the knowledgeof how to use it effectively.MARK CEJER is a marketing director forKeithley Instruments, Inc. (www.keithley.com),Cleveland, Ohio, which is part of the Tektronixtest and measurement portfolio.HB-LED testing fundamentalsA typical diode’s electrical I-V (currentvoltage)curve is shown in Fig. 1. Althougha complete test sequence could includehundreds of points, a limited sample isgenerally sufficient to probe for the figuresof merit. Many HB-LED tests involvesupplying a known current and measuringthe resulting voltage, or vice-versa, soa single piece of hardware that synchronizesboth functions can result in quickersystem setup and enhanced throughput.Testing can be done at the die level (bothwafer and package) or the module/subassemblylevel. In the latter case, HB-LEDsare connected in series and/or parallel;therefore, higher currents are typicallyinvolved, sometimes up to 50A or more,depending on the application. Some dieleveltesting can require 5-10A, dependingon die size.Forward-voltage (V F ) test: A forwardvoltagetest verifies the device’s forwardoperating voltage. When a forward currentis applied to the diode, it begins to conduct.During the initial low-current values,the voltage drop across the diode increasesrapidly but levels off as the drive currentincreases. The region of relatively-constantvoltage is where the diode normallyoperates. Results are often used in binningdevices because an HB-LED’s V F is relatedto its chromaticity.Optical tests: Forward current biasing isalso used for optical tests because currentflow is closely related to the amount of lightemitted by an HB-LED. A photodiode orintegrating sphere can be used to capturethe emitted photons to measure opticalpower. This light is converted to a currentthat’s measured using an ammeter or onechannel of a source-measure unit (SMU).Reverse breakdown voltage (V R ) test: Anegative bias current applied to an HB-LED allows probing for its reverse breakdownvoltage. The test current should be setto a level where the measured voltage valueno longer increases significantly when currentis increased slightly. At voltages higherin magnitude than the breakdown voltage,large increases in reverse-bias current produceinsignificant changes in reverse voltage.The V R test is performed by sourcing alow-level reverse-bias current for a specifiedtime, then measuring the voltage dropacross the HB-LED. Results are typically inthe tens of volts.Leakage current testing: Moderate voltagesare normally used to measure the currentthat leaks (I L ) across an HB-LED whena reverse voltage less than breakdown isapplied. In production testing, it is commonpractice to ensure only that leakagedoesn’t exceed a specified threshold.Boosting test throughput in productionAt one time, manufacturers used an externalPC to control all aspects of HB-LED productiontesting; in each element of a testsequence, the sources and instruments hadto be configured for each test, perform thedesired action, and then return the datato the PC, which evaluated the pass/failcriteria and determined where to bin theI L testV R testIV F testFIG. 1. Typical DC current-voltage (I-V)curve for an HB-LED, showing test points(not to scale).DUT (device under test). Transferring commandsfrom the PC and results back to itate up a lot of test time.The latest generation of smart instruments,including Keithley’s new Model2651A High Power System SourceMeterinstrument (Fig. 2), is optimized to boostthroughput substantially by minimizingcommunication traffic. The majority ofthe test sequence is embedded in the testinstrumentation within a script and isexecuted by a microprocessor that allowsVLEDsmagazine.com NOVEMBER/DECEMBER 2011 71Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM qMM MQmags| Next Page q qTHE WORLD’S NEWSSTAND ®

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM | Next PageqqM qMMQmagsTHE WORLD’S NEWSSTAND ®LED production | TESTINGcontrol of the test sequence, with internalpass/fail criteria, calculations, and controlof digital I/O. The microprocessor stores auser-defined test sequence in memory andexecutes it on command to all SourceMeterinstruments in the test configuration,reducing set-up and configuration time.Communication between units takes placevia TSP-Link technology, a high-speed trigger-synchronization/inter-unitcommunicationbus, which connects multiple instrumentsin a master/slave configuration. Thiseliminates time-consuming GPIB (generalpurpose interface bus) traffic, and greatlyenhances system throughput.LED test system for a single deviceA system configuration for testing oneHB-LED at a time is shown in Fig. 3. Thecomponent handler transports the individualHB-LED to a test fixture, which isshielded from ambient light and housesa photodetector (PD) for light measurements.Two SMUs are used: SMU #1 suppliesthe test signal to the HB-LED andmeasures its electrical response, while SMU#2 monitors the photodiode during opticalmeasurements.The test sequence is programmed tobegin using a digital line from the componenthandler that serves as a start-of-test(SOT) signal. After the instrument detectsthis signal, the test sequence begins. Oncecompleted, a digital line signals measurement-completestatus to the componenthandler. In addition, the instrument’sbuilt-in intelligence performs all pass/failoperations and sends a digital commandthrough the instrument’s digital I/O port tothe component handler to bin the HB-LEDbased on the pass/fail criteria. Then, twoactions can be programmed to take placesimultaneously: data is transferred to thePCLANFIG. 2. Model 2651A High Power System SourceMeter instrument.PD26xxASMU #2LED2651ASMU #1PC for statistical process control, and a newDUT moves into the test fixture.Production testing of HB-LEDsTo achieve acceptable throughput, productiontest systems measure multiple partssimultaneously. Fig. 4 illustrates a devicetest system for three HB-LEDs that has onephotodiode (PD) channel.Junction self-heating can contributesignificant measurement error in HB-LED production testing. As the junctionheats over time, for a constant forwardbiascurrent, the forward voltage drops, soit’s crucial to manage device self-heatingto ensure accurate, repeatable measurements.Self-heating can be minimized byreducing the amount of time the test willtake, which in turn reduces the amount oftime necessary for the test current to beapplied to the device. Smart instrumentscan simplify configuration of the devicesoak time (which allows any circuit capacitanceto settle before the measurementbegins), as well as the integration time(which defines how long it takes the analog-to-digital(ADC) to acquire the inputsignal), because both factor into how longthe test will take. New SMU instruments,including Keithley’s 2651A, have digitizingComponenthandlerTest fixtureBinsDigital lines(DIO)FIG. 3. A test system for a single HB-LED, which uses twosource-measure units (SMU).50% duty cycle75% duty cycle25% duty cycleADCs, which can sampleat speeds up to onemicrosecond per pointor up to 50 times fasterthan high-performanceintegrated ADCs. Thesehigher measurementspeeds further improveoverall test times.The use of pulsed measurementsminimizestest times and junctionself-heating. ModernSMUs with high pulsewidthresolution ensure precise controlover how long power is applied to the device.Pulsed operation also allows these instrumentsto output current levels well beyondtheir DC capabilities.High-power LED module testingThe demand for a lot of light in a small packagehas led lighting manufacturers to developFIG. 5. In pulse-width modulation,the pulse level and frequency remainconstant, but the duty cycle is varied.high-power LED modules, which often consistof one or more large-die LEDs. When multipledie are present, they’re either wired inparallel or in series, depending on the applicationand the available power source. The die ofthese LEDs can be much larger than those oftypical HB-LEDs and can handle much highercurrents. In fact, it’s common for a single dieto be required to withstand current levels ashigh as 10A.Obviously, testing high powerHB-LED modules demands hardwarethat can deliver a lot of powerto the DUT. Although SMUs’ abilityto handle both sourcing and measurementnormally makes them the72 NOVEMBER/DECEMBER 2011 LEDsmagazine.comPrevious Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM qMM MQmags| Next Page q qTHE WORLD’S NEWSSTAND ®

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM | Next PageqqM qMMQmagsTHE WORLD’S NEWSSTAND ®LED production | TESTINGbest solution for testing LEDs, most SMUson the market simply can’t deliver the levelof power that testing high power HB-LEDmodules requires. Most instrument-basedSMUs are capable of delivering only 20Wof power or less, but this application oftenrequires 100W or more. Keithley’s 2651Ainstrument is capable of delivering up to200W of continuous DC power and up to2000W of pulsed power.PD LED 1DIOPC LAN26xxA 2651ATSP-linkFIG. 4. Production setup for testing three HB-LEDs.LED 22651ALED 32651APulse-width modulation and HB-LEDsPulse-width modulation (PWM) offers a wayto control the brightness of LEDs. Althoughit’s also possible to control an LED’s brightnesssimply by lowering the forward drivecurrent, this method is undesirable becausethe color of the light produced will changeslightly with current level. PWM is the preferredtechnique because it uses a constantcurrent level for each pulse and thereforeoffers greater consistency in the color of thelight produced. PWM also offers more-linearcontrol over brightness, and greater powerconversionefficiency.In this technique, the current through theLED is pulsed at a constant frequency witha constant pulse level, but the width of thepulse is varied (Fig. 5), which changes theamount of time the LED is in the ON state, aswell as the perceived level of brightness. TheLED is actually flashing but at such a highfrequency that the human eye can’t distinguishit from a constant light level.Given that LEDs are often used withPWM, it’s only appropriate that they betested with PWM techniques. As part ofPWM testing, an LED is usually tested byrunning a series of pulses through it whileusing a spectrometer to take an integratedmeasurement of the light output over thecourse of many pulses. This measurementmay take tens or hundreds of millisecondsto complete. During the pulsed output, theforward voltage is measured on every pulseto look for changes as the temperature of theLED rises._____________LEDsmagazine.com NOVEMBER/DECEMBER 2011 73Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM qMM MQmags| Next Page q qTHE WORLD’S NEWSSTAND ®

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM | Next PageqqM qMMQmagsTHE WORLD’S NEWSSTAND ®_________________Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM qMM MQmags| Next Page q qTHE WORLD’S NEWSSTAND ®

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM | Next PageqqM qMMQmagsTHE WORLD’S NEWSSTAND ®drivers | BACKLIGHTINGMatching driver design with LED backlightscheme optimizes energy savingsLED backlighting is a requisite for TVs to meet more demanding Energy Star requirements, explainsGYAN TIWARY, and matching the driver design to the backlight implementation delivers maximumenergy savings.GYAN TIWARY (gtiwary@iWatt.com) is thesenior vice president and general manager ofthe DC/DC Business Unit at iWatt, Inc. (www. ___iwatt.com).______Direct dimming*TABLE 1. Characteristics of LED backlight types.Energy Star requirements for flat-paneltelevisions have become more stringentin recent years. If the Energy Star6.0 proposal is accepted, it mandates that allTVs larger than 50 inches must consume nomore than 85W of power by the fall of 2012.Two years ago, such TVs consumed close to200W. These strict standards that attemptto curb power consumption worldwide haveled to significant innovations in LCD TVs,especially in the backlight unit (BLU) whichis a major source of power consumption.LED-based BLU can offer significant powerreduction although the driver design mustbe optimized for the different direct- andedge-backlit schemes.Active power consumption in an LCD TVconsists of two main components: displaypower and baseline power. Baseline powerencompasses the video-processing aspectsof the TV and the main power supply, andtypically accounts for about a third of thetotal power. Various components and scenarioswill impact baseline power consumption,such as frame rate and power supplyefficiency. In a 3D TV scenario, for example,additional image processing, a faster refreshrate and increased brightness can increasebaseline power by 50-100% relative to standardTVs. Similarly, smart Internet-connectedTVs require a higher performanceprocessor, additional memory, and otherelements adding a few watts of power. Still,the baseline power adders are a small fractionof the overall TV power consumption.Display power refers to the power consumedby the LCD screen, BLU, and associatedcircuitry, and accounts for about two thirds ofthe total power consumed by a TV. Therefore,it would be logical for the industry to focus onreducing power consumption in this area.Display power usage is high largelybecause the luminous efficiency of LCD TVsis very poor. An LCD panel has an extremelylow transmittance level, in the 4-6% range,as the light travels from the BLU throughthe light guide, diffuser, optical film, andcolor filter. For example, if the BLU generates8000-10000 cd/m² of luminance, thenthe final, visible-to-the-eye output mighttypically be between 380-450 cd/m².The BLU must therefore generate considerablelight and consumes the largestamount of power inside an LCD TV. Anyimprovement in BLU efficacy will lead todramatic power savings for the TV.Not too many years ago, cold cathode fluorescentlight (CCFL)-backlit LCD displayswere the biggest power guzzlers inside LCDSegment-edge/hybrid dimming*Edgedimming**Picture quality Best Medium WorseEnergy consumption Lowest Medium HighestForm factor Thicker (by

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM | Next PageqqM qMMQmagsTHE WORLD’S NEWSSTAND ®drivers | BACKLIGHTINGLED string voltage (V)200+15010050Increasing zone countand dimming complexityDirect litwith zonedimming40Hybrid edge-litwith segmentdimmingEdge lit80 120 160LED current (mA)200FIG. 1. Characteristics of different LED BLUs.Edge-lit BLUs were the initial configurationof choice for notebook computer screens andLCD TVs. As edge-lit BLUs were deployedover the past several years in larger displays,most people considered the picture qualityfrom these devices to be inferior to traditionalCCFL-backlit TVs.To improve picture quality and to benefitfrom the switching capability of theLEDs themselves, two other BLU schemesemerged with a heavy emphasis on dimmingselect portions of a screen. Direct-lit designsplace LEDs directly behind the screen. Suchdesigns can dim LEDs with fine granularityin small zones. Hybrid edge-lit designs placethe LEDs on the side of the screen, but stillsupport dimming of individual rectangularsegments that extend horizontally across thescreen. Both direct and hybrid schemes utilizedimming to significantly improve blacklevels, uniformity, and viewing angles, andreduce motion blur. Table 1 summarizes theBLU types and their characteristics.Driving requirements and challengesThe different BLU schemes require significantlydifferent driver architectures. Edgetypedrivers typically require very high outputvoltages (a few hundred volts) that in mostcases drive a single string of LEDs. Challengesrelated to driving multiple parallel stringssuch as matching current and forward voltagesare a non-issue. However, this BLU stylekeeps all of the LEDs illuminated at all times,which wastes power. The only energy savingscome from the baseline efficiency advantageof LEDs. The LEDs can be dimmed globally –the technique is sometimes called global dimming– but the dimming capability does notenhance the picture quality.A driver for an edge-lit TV mustutilize a high-voltage, boost topology.Typical voltage output from a TVpower supply is 12-14V so this is usedas an input supply to the driver circuit,which then boosts the voltage bya factor of 10-20 while still keeping theefficiency high.The driver itself can be a discreteDC-to-DC design or, in certain240 instances, the main power supplycan generate the high voltage directlyfrom the AC input. Efficiency requirementsfor such drivers are between90-95%. Typically over a hundredLEDs are strung together in series. Somedesigns do use multiple strings, typically 2-4,lowering the requisite string voltages.The majority of LED-backlit TVs in themarket today use the basic edge-lit design.The key challenge for edge-type drivers is tomaintain high efficiency at the high voltagewhile keeping the overall component countlow. Fig. 2 shows the typical driver architecturefor edge-lit TVs.Direct BLU driver issuesIn direct backlighting, LEDs are positionedright behind the LCD panel and controlled insmall zones. Each zone contains a few LEDsthat can be locally controlled. The type andnumber of zones are manufacturer specificand based on screen size, picture quality andother factors. Picture quality improves withan increase in the number of local-dimmingzones, but this also increases LED and drivercount and hence, the cost.Fig. 3 shows the typical driver configurationfor direct- and segment-edge-backlitTVs. The drive voltage is much lower thanedge-lit designs, simplifying the issue ofdesigning an efficient driver. A direct-backlitdesign would typically have a greater numberof strings with fewer LEDs per string relativeto a segment-edge design.The main driver challenge in a direct-litdesign is one of scale. Some such TVs havemore than 100 strings or channels of LEDs.Typical drivers can handle 8-16 channels. Soa TV can require many drivers.In a typical direct-lit TV, LEDs chalk upabout 40% of the total cost of the BLU bill ofmaterial, while the drivers make up another20%. The cost of the LEDs, the power theyconsume, and the system complexity are alldisadvantages.Consider the issue of the varying forwardvoltages (Vf) of the LEDs. Even after sortingthe LEDs, the varying forward voltagesamongst the many strings causes a significantamount of power to be wasted inside theTV, producing heat and increasing the chanceof thermal-stress-related LED failures.Segment-edge driversThe sheer number of LEDs and driversrequired for direct BLUs, and the cost ofthose components, has been a key reasonfor the growing popularity of the segmentedgeapproach. Moreover picture quality isnot the only purchase criteria consumersconsider. In some cases thinner form factorsare key selling points and the edge-segmentscheme enables thinner TVs. More than 60Vboost >200V1-2 strings of LEDDAC8PWMOpGroundR100+ LEDsDrivingcircuitFIG. 2. Typical edge-lit driver confi guration.segment-edge-backlit TVs were announcedin 2011 and this number is expected to growrapidly in 2012.Segment-edge dimmed TVs requireanywhere from 12-48 channels of LEDsdepending on the size of the TV and numberof segments desired by the maker.Given the high channel counts, all of thechallenges associated with drivers indirect-lit designs also apply here, albeit toa lesser degree. The aforementioned thermalproblem persists and forces the TVmaker to utilize several additional discrete76 NOVEMBER/DECEMBER 2011 LEDsmagazine.comPrevious Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM qMM MQmags| Next Page q qTHE WORLD’S NEWSSTAND ®

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Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM | Next PageqqM qMMQmagsTHE WORLD’S NEWSSTAND ®design forum | DIMMING PORTABLE DEVICESAnalog technique simplifies LEDdimming in portable applicationsProducts ranging from mobile handsets to LED fl ashlights require SSL dimming control, explainsCHRISTOPHER JAMES GLASER, and analog implementations can offer better effi ciency than PWMdimming in such products.Portable equipment that uses LEDbasedsolid-state lighting (SSL)requires an efficient drive circuitthat prolongs battery life, as well as dimmingoptions to adjust the light output forthe ambient lighting conditions. LED dimmingis necessary in applications such asthe backlight for smart phones or portableGPS navigation systems to ensure an easilyreadable display in both bright sunlightand the dark of night. In flashlights, a usermay deem longer battery life more importantthan delivering the most light possible.Either analog dimming or pulse-widthmodulation(PWM) dimming can be usedin such applications. By using an innovativeapproach to creating a reference voltage, ananalog design can prove more efficient thanPWM-based designs.Both analog and PWM dimming techniquescontrol the LED drive current, whichis proportional to the light output. Analogdimming is simple, requires the least controloverhead, and generally is more efficientthan PWM dimming due to the lowerforward voltage of the LEDs at lower drivecurrents.Analog dimming, however, requires ananalog voltage to be generated by a separatevoltage reference – perhaps using theoutput of an RC filter on a square waveinput signal, or from an expensive digitalto-analogconverter (DAC). The circuit inFig. 1 eliminates the complexity of thesetechniques to provide simple, cost-effectiveanalog dimming based on varying aCHRISTOPHER JAMES GLASER is anapplications engineer in TI’s battery powergroup (www.ti.com).VIN4V to 17V 11PVIN12PVIN4.7μF10AVIN13ENR1100k9SS/TRDEF8TPS62150RGTFSW PGND PGND7 16 15potentiometer. The total solution is an efficient,low-cost, low-component-count LEDdriver for a single high-current LED, suchas Osram’s Golden Dragon, for use in small,battery-powered devices.Circuit operationThe circuit requires a voltage-regulating,synchronous, buck converter that providesoutput currents of up to 1A from up to a17V source, such as the TPS62150. In Fig.1, this buck converter regulates the currentin the LED by using the feedback (FB)pin to control the voltage across the senseresistor R2. The FB voltage is controlled bya combination of a precision internal referencevoltage, which typically is 0.8V, andan external input on the SS/TR (slow startand tracking) pin.When the voltage on the SS/TR pin isbelow 1.25V, the FB pin voltage tracks theSS/TR pin voltage by a factor of 0.64 asexpressed by this equation –V FB = 0.64 *SWSWSWV OS12314FB5PG4AGND6ETPac172.2 μH LED current:1A maxFIG. 1. LED driver with analog dimming enabled by the potentiometer R1.R20.1522μFV SS/TR . By controlling the FB voltage andtherefore the voltage across R2, the IC variesthe current that drives the LED.The SS/TR pin has a built-in currentsource of typically 2.5 μA. This is commonlyused to charge a capacitor and createa smooth, linear ramp-up of the SS/TRpin voltage. In a typical buck converter, thisthen creates a linear and well-controlledramp-up of the output voltage while reducinginrush current from the input supply. Forthis design, a resistor to ground produces aconstant voltage at the SS/TR pin instead.A potentiometer is placed on the SS/TRpin to keep the voltage at that pin between250 mV (potentiometer = 100 kΩ) and 0V(potentiometer = 0Ω). Recalling the equationabove, that means the voltage on theFB pin varies between 160 mV and 0V. Witha 0.15Ω resistor for R2, the LED current variesbetween 1.07A and 0A. Since the FB pinvoltage is linearly related to the SS/TR pinvoltage, the potentiometer provides linear78 NOVEMBER/DECEMBER 2011 LEDsmagazine.comPrevious Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM qMM MQmags| Next Page q qTHE WORLD’S NEWSSTAND ®

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM | Next PageqqM qMMQmagsTHE WORLD’S NEWSSTAND ®design forum | DIMMING PORTABLE DEVICESanalog dimming as shown in Fig. 2.This circuit has very good efficiency,since the FB pin voltage is a relatively lowvalue. That low voltage reduces the lossesin the sense resistor, R2. In addition, theTPS62150 employs a power-save mode atlight load currents to keep the efficiencyhigh for the majority of the load range.Fig. 3 shows the efficiency of the circuitin Fig. 1 operating from a 12V input, andusing TDK’s VLF3012ST-2R2 inductor in theswitching output.The efficiency of this circuit can beimproved, but at the cost of circuit size.For example you could connect the FSW(switching frequency) control pin to theoutput voltage, which reduces the operatingfrequency, and/or select a differentinductor with lower DCR (DC resistance)and/or better AC loss characteristics. Efficienciesin excess of 90 percent are possible,although these two methods wouldlikely take more circuit board area to realize.The design presented in Fig. 1 deliversa small solution size with good, albeit notthe greatest, efficiency.Circuit limitationsSince this circuit uses an imprecise analoginput (a manually adjustable potentiometer)for regulating the LED current, the tolerancesof the sense resistor, potentiometerI out (A)1.21.00.80.60.40.20.00.000.05Dimming linearity0.10 0.15V SS/TR (V)resistance, and SS/TR pin current and howthey affect the LED brightness do not matter.If the LED is too bright, the user simplyturns the potentiometer resistance down.If it is too dim, simply turn the potentiometerresistance up. With a multi-turnpotentiometer, theLED brightness canbe sufficiently controlledfor ordinaryapplications, suchas flashlights andbacklights.One drawback ofthis design is the offsetbetween the SS/TR pin and FB pinvoltages. When theSS/TR pin is pulledall the way down to0V, by decreasing0.20FIG. 2. Dimming linearity of the circuit in Fig. 1, in whichdimming is achieved using a potentiometer.0.25Efficiency (%)10095908580750.00.1the potentiometer resistance, there is stillabout 50 mA of current flowing throughthe LED. Thus, the LED cannot be turnedoff completely unless you add a switch toground with a pull-up resistor connectedto the EN (enable) pin.Other analog dimming methodsThe advantage of using the potentiometercircuit described in this article is its simplicityand cost-effectiveness. The requiredanalog voltage for analog dimming is generatedby a precise current source alreadyin the IC which is then translated to a correspondinglight output by a user-adjustableresistor. Besides this potentiometer,no other components are required. Theinput for the dimming,the potentiometer,is the onlyneeded component.If this precise currentsource were notpresent, other methodsof generating therequired analog voltagefor analog dimmingwould have tobe considered. Sometraditional optionsinclude: using a separatereference voltageIC that createsa precise analog voltage; varying the dutycycle of the PWM output of a microcontrollerthrough an RC filter to generate theprecise analog voltage; or using a microcontrollerwith a DAC to generate the preciseanalog voltage.0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9LED current (A)FIG. 3. Effi ciency of the circuit in Fig. 1 over the dimming range.1.0Each of these three options requires aninput from the user to vary the light. Withthe reference voltage IC, a potentiometer isstill required as an input to the IC to adjustthe voltage and control light output. Thereference IC alternative is more costly thanthe simple option focused on in this article.The final two alternatives require amicrocontroller and again add cost. Whilesmart phones and GPS systems include amicrocontroller, the typical flashlight doesnot. The decision on pursuing such methodsdepends on the application at hand assome products would benefit from a moreelegant user interface, perhaps with touchscreencontrol.Option three replaces the potentiometerwith a larger and more expensive DAC. TheDAC could offer better granularity in theoutput analog voltage, and therefore morepreciselight control than does the potentiometer.The application should dictatewhether the expense is justified.Using a potentiometer on the SS/TR pinof the buck converter is a simple, small, andlow-cost method to provide linear analogdimming to a high-current LED in applicationssuch as backlights and flashlights.With analog dimming, the efficiency overmost of the dimming range remains near 85percent from a 12V input supply. The completecircuit requires only six components,plus the high-power LED.MORE: Visit the Drivers & Control section ofthe LEDs Magazine website for news, featuresand product information - www.ledsmagazine.com/Drivers.LEDsmagazine.com NOVEMBER/DECEMBER 2011 79Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM qMM MQmags| Next Page q qTHE WORLD’S NEWSSTAND ®

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM | Next PageqqM qMMQmagsTHE WORLD’S NEWSSTAND ®last wordLED industry tales from TaiwanA recent visit to Taiwan highlighted a number of issues in the local LED industry,writes ELLA SHUM, Director of HB-LED Research with STRATEGIES UNLIMITED.On a recent trip to Taiwan, it becameclear that the overall feeling amongLED industry players is prettygloomy. I came across a variety of issues relatingto LED pricing, personnel, and subsidies.However, one company, Lextar, managed togo public in September (www.ledsmagazine.com/news/8/9/35), so the news is not all bad.Concerning pricing, the industry wasshocked by rumors of a quote of $0.08 givenby a large Korean vendor for a 5630-typepackaged LED for lighting. Such packagesare often used in retrofit lamps that do notrequire high lumen output. The price is equivalentto approximately 400 lm/$. Even in Taiwan,where the art of cost-cutting is mostrefined, this price is looked upon as belowcost. A curious observer would note that asimilar package from the same vendor designatedfor backlight applications is moreexpensive. The conclusion varies, but mostpeople feel this may be an attempt to buy thelighting market, or that it is another tacticto put downward pressure on prices for thewhole industry and to force weaker playersout. Whatever it is, once the prices go down,they don’t usually go back up.Retaining personnel is a challenge forTaiwanese companies: whole teams of engineershave moved from Taiwan to China,and with a 4-5-fold increase in salary, thetemptation can be irresistible. Teams frequentlymove together, but this is essentiallya one-way street since no Taiwanesecompanies will ever hire them again. Whenthere were many start-ups in China buyingMOCVD systems last year, bidding warswere frequent for these teams. What’s interestingis that quite a few of these relocatedpersonnel have totally changed their identity.The suspicion is that these people tookvaluable IP with them. Due to the politicalsituation between the two regions, thereis no legal way to pursue or extradite suspectedcriminals from China to Taiwan. Ina Confucian society, where ancestry worshipis core to the cultural identity, changingone’s name means denying one’s ancestors.I only hope the money is worth it.I met someone from Taiwan whose companysold energy-saving electronic ballastsfor florescent lights. He secured a contractto supply 2700 ballaststo a major US retail chainstore.The product performedas specified, saving 25-30%energy, and payback was 1.5years based on 24/7 usage. Myfriend called every 6 months tocheck on the products and seeif follow-on orders were goingto come. After a couple ofyears, he gave up calling. Fouryears after the initial installation,he received an orderfor 775,000 units. Similarly, after Walmarttested LED lights from GE in their refrigeratordisplays, it took them 3 years to decide toroll out LEDs in all stores. This illustrates thechasm between the early adopters and theearly majority. Time has passed since thesestories happened, and the chasm is probablyshorter now. However, if you are a start-up inthe LED lighting market, what is your strategyfor crossing the chasm?A new kind of net profitThe mainstream semiconductor industryis used to feast and famine. During downcycles,weaker players leave the scene, whilestronger ones survive to reap the profit in thenext upturn. In this particular down-cycle,we have noticed something interesting whencomparing the net profits of two LED chipcompanies; Epistar from Taiwan and SanAnfrom China.Epistar’s net profit for the first half of2011 was NT 1.1 billion ($35.7 million), witha margin of 11%. In the same period in 2010,the margin was 29% on NT 2.7 billion ($88.6million) net profit. In contrast, SanAn’s netprofit margin for the first half of 2011 wasRMB 459 million ($72.3 million) with 64%margin. In the same period in2010, the margin was 56% onRMB 202 million ($31.8 million)net profit. Why the hugedifference in profit marginbetween the two companies?Why did SanAn’s margin andnet profit go up in 2011 whenthe overall market crashed?Upon further analysis,SanAn received RMB 583 million($91.8 million) in subsidiesfor the first 6 months of 2011from the government, and that is countedtowards its net profit. If you take out the subsidies,it lost RMB 124 million ($19.5 million).For the rest of 2011, SanAn still has RMB 928million ($146.2 million) in subsidies to add toits balance sheet.Another new player in the China LEDworld is ETI (Elec-Tech International), whichreceived subsidies totaling RMB 534 million($84.1 million) in 2011. This is an amounthigher than the net profit of the company’sLED business.I think we will have to invent a new term forthis type of “net profit,” to distinguish it fromthe hard earned “net profit” we are used to.MORE: View an extended version atwww.ledsmagazine.com/features/8/11/3.80 NOVEMBER/DECEMBER 2011 LEDsmagazine.comPrevious Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM qMM MQmags| Next Page q qTHE WORLD’S NEWSSTAND ®

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM | Next PageqqM qMMQmagsTHE WORLD’S NEWSSTAND ®Isolated LED Current Controlwith Active PFC90V to 265VACRegulatedLED Current(Typically±5%)V INDCMV IN_SENSEFBV REFLT3799CTRL3GATECTRL2SENSECTRL1V INTVCC20WLEDPowerFaultFAULTCT COMP +GNDCOMP –Complete TRIAC Dimmable SchematicTRIAC Dimmable LED Driver Needs No Opto-couplerOur LT ® 3799 isolated LED controller with active power factor correction (PFC) is specifically designed for driving LEDsover a wide input range of 24V to 480V+. It is ideal for LED applications requiring 4W to over 100W of LED power andis compatible with standard TRIAC in-wall dimmers. The LT3799’s unique current sensing scheme delivers a well regulatedcurrent to the secondary side with no opto-coupler, enabling it to provide ±5% LED current accuracy. It also offers lowharmonic distortion while delivering efficiencies as high as 90%. Open and short LED protection ensures long termreliability and a simple, compact solution footprint addresses a wide range of applications.LED Current vs TRIAC AngleLT3799 Demo Board (25W)Info & Free SamplesLED Current (A)1.21.00.80.60.4120V app0.2220V app00 30 60 90 120 150 180TRIAC Angle (Degrees)www.linear.com/product/LT37991-800-4-LINEAR______________, LT, LTC, LTM, Linear Technology and the Linear logo areregistered trademarks of Linear Technology Corporation. All othertrademarks are the property of their respective owners.Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM qMM MQmags| Next Page q qTHE WORLD’S NEWSSTAND ®

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM | Next PageqqM qMMQmagsTHE WORLD’S NEWSSTAND ®CREE XLAMP ® LIGHTING-CLASS LEDsXLAMP XM-L LEDsOPTIMIZED FOR HIGH LUMEN APPLICATIONSIndustry’s highest performance lighting-classLED— delivers up to 1000 lumens at 10W, 3ALowers system cost with breakthrough outputand high efficacyXLAMP XM-LEASYWHITE ® LEDsOPTIMIZED FOR 20-25W HALOGENREPLACEMENTSHigh lumen output in a small form factorIndustry’s tightest color consistencyXLAMP MT-GEASYWHITE ® LEDsOPTIMIZED FOR HIGH-OUTPUT, SMALL-FORM-FACTOR, DIRECTIONAL-LIGHTINGAPPLICATIONSHigh lumen output—up to 1550 lumens at25 W, 85°CAvailable in 6V and 36V optionsCREE XLAMP LEDs ARE APPLICATIONOPTIMIZED FOR LOWEST SYSTEM COSTREVOLUTIONARY!Cree XLamp ® Lighting-Class LEDs arepurposefully designed to deliver the industry’sbest performance and optimized specificallyfor distinct applications. This makes it easy todesign in the brightest, most efficient LED.Our product portfolio enables revolutionarydesigns for either brighter, more efficientluminaires with fewer LEDs or space savingfixtures using less LEDs.So whether you’re designing exterior wide arealighting or a tightly focused indoor directional,you can have excellent performance and loweryour system cost.Get samples of Cree XLamp LEDs or contacta Cree Solutions Provider at cree.comor call us at +800.533.2583Get Cree reference designs at cree.com/refPrevious Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | SubscribeqMqM qMM MQmags| Next Page q qTHE WORLD’S NEWSSTAND ®