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Contents | Zoom in | Zoom out For navigation instructions please click here Search Issue | Next PageAPRIL 2009LEDsmagazine.comTECHNOLOGY AND APPLICATIONS OF LIGHT EMITTING DIODES+ControlWhy LED dimmingis vital P.21SIL 2009LED lighting liftsthe mood P.15ThermalHeat managementfor LEDs P.41 & P.45LightingNext generationluminaires P.26Contents | 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 | Next PageTHE NEXT GENERATION CONSTANT CURRENT HIGH POWERLEAll-in-oneABE FMaGSFig. original size- Ready to use - Plug & Play- Up to 1.2A Constant Current- PWM/Digital Dimming- 100% linear Analog Dimming- 96% Efficiency- Wide Input Voltage Range- Low Emissions (EN-55022)- Long lifetime up to 600,000hrs.- Ultra Miniature Design- High op. temperature/85 o CNEW!Wired version.www.recom-power.comNo more designing, certifying and procuring.*To get your free LED-Driver Sample send an e-mail with the subject: “Free RCD-LED-Sample” to: admin@recom-power.comPrevious Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | Next PageABE FMaGS

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Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | Next PageABE FMaGSAprilISSUE 262009Cover StoryJournée Lighting won a Best in ClassAward for its AZARA track-mountedluminaire (p.26). Photo by HollandAlexander.15featuresSTRATEGIES IN LIGHTLighting on track to provide bright future for LEDsmarketHassaun Jones-Bey, Tim Whitaker21 DIMMINGControlling the expectations of LED lightingconsumers: Why dimming is so importantChris Salvestrini, Amanda Beebe, Lutron Electronics29 STANDARDSWhy 2008 was the Year of LED StandardsKevin Dowling, Philips Color Kinetics333541DESIGN FORUMAvoid themal runaway when drivingmultiple LED stringsSteve Roberts, RECOM GmbHDIRECTIONAL LIGHTINGDesigning with LED directional lights: Theimportance of delivering lux on targetQuata Ocano, LedEngin Inc.HEAT REMOVALTaking the heat out of LED fi xturesFrançoise Von Trapp712265052columns/departmentsNEWS + VIEWSLED lighting lifts the gloomLA looking at LED street lightsPerkinElmer buys Opto TechnologyNichi, Luminus form partnershipFUNDING + PROGRAMSFrench CITADEL project looksat LED lighting in buildingsFOCUS ONNext Generation LuminairesPRODUCT FOCUSLAST WORDLighting market presents numerousopportunities for LED manufacturersBernhard Stapp, Osram OptoSemiconductors45 THERMALManaging heat in power LED systemsfor optimal performanceRudi Hechfellner, Philips Lumileds Lighting Co.Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | Next PageABE FMaGS

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | Next PageABE FMaGSLEDs MAGAZINE onlineWebcastsLED Lighting Fixture Market — Challenges and OpportunitiesDATE: May 2009PRESENTER: Vrinda Bhandarkar, Senior Market Research Analyst,Strategies UnlimitedLED Luminaire Photometry & Performance TestingORGINALLY BROADCAST: March 2009PRESENTATIONS FROM: Intertek and SphereOpticsVisit www.ledsmagazine.com/webcasts to accessall of our archived presentations.ArticlesFuture remodels HQ building with LEDswww.ledsmagazine.com/features/6/3/8Energy Star Lighting Partner Meeting remembers the Alamowww.ledsmagazine.com/features/6/3/5Alamo revisited: Further notes from Energy Star meetingwww.ledsmagazine.com/features/6/3/9Alliance Optotek’s LED street light design technologywww.ledsmagazine.com/features/6/3/1Featured Companies & ProfilesThe following have recently been added to the LEDs Magazine website asFeatured Companies (see www.ledsmagazine.com/buyers/featured):American Bright Optoelectronics Corp. • Endicott Research Group(ERG), Inc. • Helio Optoelectronics Corp. • Opto Diode Corp. • RECOMPower, Inc. • Signcomplex Ltd. • Vossloh-Schwabe OptoelectronicCompany Profiles have also been added for the following (see ____ www.ledsmagazine.com/Profiles):Endicott Research Group (ERG), Inc. • RECOM Power, Inc. • Signcomplex Ltd.__________________GROUP PUBLISHER Shannon E. Alo-Mendosashannona@pennwell.comTel. +1 603 891 9137EDITOR Tim Whitakertwhitaker@pennwell.comTel. +44(0)117 946 7262MANAGING EDITOR Julie MacShanejuliem@pennwell.comTel. +1 603 891 9221CONTRIBUTING EDITORS Brian Owen, Hassaun Jones-Bey,Francoise von TrappMARKETING MANAGER Luba HrynykPRESENTATION MANAGER Cindy ChamberlinPRODUCTION DIRECTOR Mari RodriguezSENIOR ILLUSTRATOR Christopher HippAUDIENCE DEVELOPMENT Debbie BouleyEDITORIAL OFFICES PennWell Corporation, LEDs MagazineCorporate Offices98 Spit Brook Road, LL-1Nashua, NH 03062-5737Tel: +1 603 891-0123Fax: +1603 891-0574www.ledsmagazine.comSALES OFFICESSALES MANAGER Mary Donnelly(USA) maryd@pennwell.comTel. +1 603 891 9398SALES MANAGER Joanna Hook(EUROPE) joannah@pennwell.comTel. +44(0)117 946 7262SALES MANAGER Manami Konishi(JAPAN) manami.konishi@ex-press.jpTel: +81 3 5645 1271SALES MANAGER Mark Mak(CHINA & HONG KONG) markm@actintl.com.hkTel: +852 2838 6298SALES MANAGER Alice Chen(TAIWAN) alice@arco.com.twSALES ADMIN Cindy Yang(TAIWAN) cindy@arco.com.twADVERTISERS indexAristo Engineering PTE Ltd. 2Carclo Technical Plastics 50Citizen Electronics Ltd. 5Cree Inc.C4D-Led Illumination 50Technologies Ltd.Edison Opto Corporation 14Everlight Electronics 20Co Ltd.Evident Technology C2Fawoo Technology 23Fraen 48, 50Fusion Optix 38Imagineering, Inc. 9Jenoptik Polymer 49Systems GmbHKhatod 50Kingbright Electronic 24Europe GmbHKingsun 22, 50OptoelectronicsLambda Research 13LEDdynamics 46LedEngin 50,51Lutron 51Macroblock Inc. 31Mean Well USA Inc. 17Messe Frankfurt GmbH 37Ocean Optics 51Optical Research Assoc. 32ORB Optronix 34Osram Opto 6Semiconductors GmbHPerkinelmer 39OptoelectronicsQuasar Light Co Ltd. 10Recom Power 1SeesmartLED 11Seoul Semiconductor C3Co Ltd.Shin-Etsu Silicones 30of America Inc.Sichuan Jiuzhou 25Electric GroupSigncomplex Ltd. 43StellarNet 34Supertex Inc. 49Terralux 51The Bergquist Company 44UPEC 51USHIO America 28Vossloh Schwabe 51OptoelectronicCORPORATE OFFICERSCHAIRMAN Frank T. LauingerPRESIDENT AND CEO Robert F. BiolchiniCHIEF FINANCIAL OFFICER Mark C. WilmothTECHNOLOGY GROUPSENIOR VICE PRESIDENT Christine A. ShawSENOIR VP OF AUDIENCE Gloria S. AdamsDEVELOPMENTVP INTERNET SERVICES Tom CintorinoSUBSCRIPTIONS: For subscription inquiries:Tel: +1 847 559-7330;Fax: +1 847 291-4816;e-mail: led@omeda.com;ledsmagazine.com/subscribeIn Europe: Mailfast, JFK/BOS/850858,P.O. Box 66,Hounslow, United Kingdom TW5 9RT;Fax: 44 20 7504 8207We make portions of our subscriber list available to carefullyscreened companies that offer products and services that maybe important for your work. If you do not want to receive thoseoffers and/or information via direct mail, please let us know bycontacting us at List Services Magazine Name, 98 Spit BrookRoad LL-1, Nashua, NH 03062.Copyright © 2009 PennWell Corp. All rights reserved. Contents ofthis publication may not be reproduced in any form without priorwritten consent of Publishers.4 APRIL 2009 LEDsmagazine.comPrevious Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | Next PageABE FMaGS

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Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | Next PageABE FMaGSwww.osram-os.comLEDs for General Lighting SolutionsOSRAM Opto Semiconductors empowers lighting solutions for today and tomorrowPrevious Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | Next PageABE FMaGS

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | Next PageABE FMaGSMARKETSLED lighting lifts the gloomnewsviewsAlthough the high-brightness LED market looks set todeflate in 2009, the general industry mood remains positive,with certain sectors such as LCD backlighting, andlighting in particular, providing cause for optimism. BobSteele of Strategies Unlimited, a market research firm,says that the market for packaged HB-LED devices grewby 11% in 2008, but is likely to shrink by 5% in 2009 (seep.15). The fastest growing sector of the device market in2008 was lighting, although this remains small in size(below $0.5 billion). However, a separate market studyby the same firm indicates that the market for LED lightingfixtures will reach $2.14 billion in 2009 and grow to$5.33 billion. At the LED device level, visibility remainspoor. Steele expects growth to resume in 2010, assumingthe economy as a whole recovers. Between 2008 and2013, the compound average annual growth rate is predictedto be 19.3%, with the market reaching $12.4 billionin 2013. ◀OUTDOOR LIGHTINGLA looking at LEDstreet lightsThe City of Los Angeles, with help from the Clinton Climate Initiative(CCI), has unveiled what could turn out to be the largest LED streetlighting retrofit project ever undertaken by a city to date. Over afive-year period, beginning in July 2009, the city’s Bureau of StreetLighting plans to replace 140,000 existing streetlight fixtures in thecity with LED units that will improve LA’s lighting quality, reduceelectricity usage, and ease what is known as sky glow — the artificialillumination of the night sky.The City of LA believes that the $57 million overhaul will lead to a40% reduction in electricity for street lighting, while reducing carbonemissions by 40,500 tons a year. Through energy and maintenancesavings the project is expected to pay for itself in 7 years. Uponfull implementation, the city will save $10 million annually.The City plans to install 20,000 fixtures in the first year beginningJuly 2009, with 30,000 in subsequent years. More than half willreplace 100-175W lamps, with a further 40% in the 200-250W range.The project also will include the installation of remote monitoringunits at all 140,000 fixtures to automatically report failures, enablingimmediate repairs.“If every city followed the example of Los Angeles and reducedthe electricity used by their streetlights by 50 percent, it would beequivalent to eliminating over 2.5 coal plants per year,” said PresidentClinton at the project launch. “We would do that while savingtaxpayers money...[and] we would also reclaim our night sky.” CCI’sOutdoor Lighting Program works with partner cities to improve theenergy efficiency of street and traffic light systems through a combinationof technical, purchasing, and project assistance. ◀MORE DETAILS: www.ledsmagazine.com/news/6/2/16BUSINESSPerkinElmer buysOpto TechnologyPerkinElmer has acquired Opto Technology Inc., asupplier of LED-based lighting components and subsystemsbased inWheeling, Illinois.The deal adds opticalsubsystems toPerkinElmer’s portfolioof high-brightnessLED components, andwill help PerkinElmerprovide SSL productsto OEMs serving thehealth, safety andsecurity markets. Bothcompanies exhibitedat Strategies in Light2009; the photo showsTaxiway light on show atStrategies in Light.an Opto Technology LED-based in-ground taxiwaylight, which requires little or no maintenance over 5years and meets the applicable standards for color andnarrow beam patterns.“The addition of Opto Technology expands PerkinElmer’spresence in the solid-state specialty lighting marketplaceand broadens the portfolio of LED subsystem capabilitiesthat we can provide to our OEM customers,” saidDavid Nislick, president of PerkinElmer’s Illumination andDetection Solutions business. ◀MORE DETAILS: www.ledsmagazine.com/news/6/2/3LEDsmagazine.com APRIL 2009 7Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | Next PageABE FMaGS

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | Next PageABE FMaGSnews+viewsCOLLABORATIONSNichia and Luminusform partnershipTwo LED manufacturers, Japan’s NichiaCorporation and US-based Luminus DevicesInc., have announced an alliance based oncross-licensing of IP, technology sharing, anda manufacturing partnership. Details of thebusiness agreement between these t woprivatelyheldcompanies areconfidential, although theysay that the shared objective is to acceleratethe adoption of solid-state lighting bycombining their technologies, includingNichia’s phosphors and epitaxial materialsand Luminus’ large-chip technology.Nichia and Luminus said they wouldcross-license IP and share critical processknowledge, resulting in new and innovativeproducts. The first two examples havealready been released; in mid-FebruaryLuminus launched two products includingthe SST-90, a large-chip white LED in a newsurface mount (SMT) package (see ____ www.ledsmagazine.com/press/18086). The packagecontains a single, monolithic die thatis nine square mm in size, and produces1,000 lumens with 10 watts input and 2,250lumens at its maximum rated drive current,with a color temperature of 6,500K. The companiessay they have also established a manufacturingpartnership, and each companywill “contribute the resources, materialsand capabilities needed to meet the qualityand performance requirements for theproducts.” ◀MORE DETAILS:www.ledsmagazine.com/news/6/2/2PATENTSSeoul and Nichia sign crosslicensingagreementTwo rival LED makers, Seoul SemiconductorCo., Ltd. of Korea and Nichia Corporation ofJapan, have settled all their various patentdisputes currently pending in the USA, theUK, Germany, Japan and Korea. The settlementincludes a cross-licensing agreementcovering LED and laser diode technologies,which will permit the companies to accessall of each other’s patented technologies.A Seoul Semiconductor spokesperson toldLEDs Magazine that its customers will nowbe more “comfortable” in buying Seoul’sLED products, because any possible supplyor litigation problems have been removed (atleast with respect to Nichia). Another consequencewill be that Seoul is now in a strongerposition to defend its IP rights againstthird-party companies, particularly thoseselling AC-driven LEDs that are similar toSeoul’s Acriche products. Two weeks afterthe cross-licensing announcement, however,Nichia issued a statement (www.ledsmagazine.com/news/6/3/3)saying that, despite_______________________the deal, there were no “understandings”or “cooperative marketing arrangements”between the two companies, who wouldremain “law-abiding competitors.”LIGHTING| web exclusiveFuture remodels with LEDsAt the Future Electronics EMEA headquarters nearLondon, it was decided to use SSL products tocreate a new lighting ambience and to replacemany of the existing halogen and CFL fi xtures.One goal was to promote the mission of FutureLighting Solutions by turning the building into abillboard for Luxeon-based lighting applications.The photo shows the boardroom, in which eachof the three drum-shaped fi xtures hanging abovethe conference table is fi tted with six warmwhiteDialight Lumidrives MR16-compatible lightengines for task lighting. The fi xtures are topped with 18 blue Luxeon I LEDs embedded ina custom light engine that bathes the ceiling in blue. Also, the 19 perimeter MR11 fi xtureswere retrofi tted with blue LED lamps to create a blue wash on the walls. Independentswitches make it possible to turn on only the blue lights when the room is not in use. ◀MORE DETAILS: www.ledsmagazine.com/features/6/3/8More Patent News:• Toyoda Gosei and Showa Denko signpatent cross-licensing agreement• Cree and Honeywell end their patentdisputeSEE www.ledsmagazine.com/news/6/3/21• Lynk Labs awarded AC LED technologypatentSEE www.ledsmagazine.com/news/6/2/7• Evident Tech issued patent for nanocrystalsynthesisSEE www.ledsmagazine.com/press/18034VENTURE CAPITALTerraLUX receives fundingAccess Venture Partners, a venture capitalfund, has closed an investment withTerraLUX, which designs and manufactureshigh-power LED OEM solutions. Thefunds will speed up TerraLUX’s expansioninto the portable and general lighting markets.TerraLUX plans to add senior managementplus development, manufacturing andengineering talent, and will also expand itsinventory to meet the increasing demandfor its patented LED light engines. “The tremendousdemand for LED lighting in theUSA is not being met today in quality, performanceor efficiency by current providers,”said Carl Kalin, VP of sales and marketing.8 APRIL 2009 LEDsmagazine.comPrevious Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | Next PageABE FMaGS

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Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | Next PageABE FMaGSnews+views“TerraLUX is entering 2009 with a plan tocapitalize upon this situation by providing anew breed of OEM LED light engines for thegeneral lighting industry.” ◀MORE DETAILS:www.ledsmagazine.com/news/6/2/26RETROFITSCRS claims record for MR16An LED-based MR16 replacement has achieveda temperature-stabilized light output of 325lm at a color temperature of 2850K, accordingto a report from LTL Testing Laboratory Inc., aUS Department of Energy CALiPER-qualifiedfacility. CRS Electronics, located in Welland,Ontario, Canada, says the lamp has a centerbeamcandlepower of 1800, a color renderingindex (CRI) of 88, and an efficiency of 53 lm/W,more than 4 times the efficiency of many halogenMR16 lamps. ◀MORE DETAILS:www.ledsmagazine.com/news/6/2/15ENTERTAINMENTETC buys Selador product lineEntertainment lighting company ETC hasentered the LED market by acquiring theSelador product line. Fred Foster, CEO ofETC, says the company was looking for a “significantinnovation in lighting” and that theSelador product line produces a “far superiorquality of color and light to anything that wehad seen before in LEDs.” Selador’s x7 ColorSystem seven-hue technology producesbright, broad spectrum whites and intensecolors equally well, rendering pigments andskin tones in a more natural way than otherLED systems, says ETC. Color matching andHSI (hue, saturation and intensity) controlof Selador products have already been integratedinto the latest software releases ofETC’s Eos® and Congo® lighting control consolelines. Selador co-founders Rob Gerlachand Novella Smith will both join ETC. ◀MORE: www.ledsmagazine.com/news/6/2/22LIGHTINGCooper Lighting acquires IMSLighting manufacturer Cooper has acquiredIllumination Management Solutions, Inc.(IMS), an Irvine, California-based companyspecializing in optics and system design forLED fixtures, and best know for its innovativeLightBAR technology. Terms of the transactionwere not disclosed. Cooper Industries’CEO Kirk Hachigian said that LED technologyis a key growth platform for the company,which over the past two years has acquiredio Lighting and UK-based Clarity Lighting._______________________________________________________10 APRIL 2009 LEDsmagazine.comPrevious Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | Next PageABE FMaGS

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | Next PageABE FMaGSThe deal will enable Cooper “to bring moreLED-based solutions to the market faster,”said Hachigian, and “positions the companyto meet the expected global demand for moreenergy-efficient solutions and infrastructureinvestment.” More details at www.ledsmagazine.com/news/6/3/10._______________________In related news, Cooper Lighting says thatits Halo® fixture (see photo) is the first LEDbasedrecessed downlight to meet EnergyStar® requirements for solid-state lighting(SSL) luminaires (specifically the DOE’s SSLv1.0 criteria). See www.ledsmagazine.com/news/6/2/5. ◀_______VISION & MEASUREMENTASSIST guidelines shed lighton nighttime illuminationThe Alliance for Solid-State IlluminationSystems and Technologies (ASSIST) haspublished a new volume in its “ASSIST recommends”series, “Outdoor Lighting: VisualEfficacy.” Developed by the Lighting ResearchCenter (LRC) the document describes a unifiedsystem of photometry that characterizesthe often tricky photometric performance oflight sources under nighttime conditions.The human visual system uses two typesof photoreceptors, cones and rods, found inthe retina. Cones are used to process visualinformation under daytime or “photopic”light levels, while rods work under completelydark “scotopic” conditions. Thereis, however, a range of light levels called“mesopic,” where both cones and rodstogether provide input to the visual system.Mesopic light levels are typically found outdoorsat night, where streetlights, cars, andbuildings all contribute to the total lightlevel. Since commercial photometry is basedentirely upon the photopic, or daytime, luminousefficiency function, it may miss-estimatethe effectiveness of some light sourcesused at night, says LRC Director Mark Rea,one of the authors.news+viewsThe proposed unified system of photometryintegrates both the scotopic and photopicluminous efficiency functions into a completesystem that can be used across the entire rangeof light levels available to the human visualsystem. The system differentially weightsthe two efficiency functions depending uponlight level. “In effect, it is a system for choosingamong commercially available light sources todeliver the same unified, rather than photopic,photometric quantity,” says Rea.The ASSIST publication provides step-bystepinstructions for calculating the unifiedluminance of a given light source based onlight level and the scotopic-to-photopic ratioof the light source. Different combinations oflight sources and light levels may produce thesame unified luminance, which indicates photometricequivalency. Therefore, the systemcan serve as a simple method for trading offlight sources and light levels under mesopicconditions, and thereby aid in the selection oflight sources for a given application. ◀________________________________LEDsmagazine.com APRIL 2009 11Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | Next PageABE FMaGS

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | Next PageABE FMaGSfundingprogramsCITADEL key parametersPROJECT BUDGET: 1.5 million Euros (~$2M)FUNDING: ADEME (French Environmental Agency)START DATE: 9 February 2009DURATION: 3 yearsMORE DETAILS: ledsmagazine.com/news/6/2/14French CITADEL project looks atLED lighting in buildingsThe research will help French laboratories to qualify commerciallyavailable LED lighting products, writes CHRISTOPHE MARTINSONS.Currently the field of lighting is in the midstof a technological revolution, unique in itshistory, with the advent of new generationsof systems based on LEDs. Significant progressachieved by semiconductor specialistshas led to robust and compact light sources,offering attractive control capabilities. Inlaboratory conditions, white LEDs reachluminous efficacies greater than those ofmost lamps used in lighting, and, above all,they exhibit far greater life expectancy. LEDsare therefore considered, as they well shouldbe, as a major component in future solutionsfor interior and exterior lighting.Despite all these advantages enthusiasticallyput forward by the semiconductorindustry, it is commonly reported that theuse of LEDs in buildings is slowed down by acertain number of complicated problems. Therequirements for successful building integrationare very specific and often unrecognizedby LED makers. Several constraints occur inbuilding applications: visual comfort, performancesustainability over time, real-lifeexpectancy, total cost assessment, and compliancewith building standards and codes.LED lighting products should be ableto fulfill the fundamental requirementsdescribed in well-established EuropeanCHRISTOPHE MARTINSONS is head of theLighting, Electricity and ElectromagnetismDivision of CSTB, St Martin d’Hères, France.Email: christophe.martinsons@cstb.fr.lighting standards such as EN 12464-1 forindoor lighting of work places. For instance,LEDs should provide the required “qualityof light” that is associated with a minimumcolor rendering index and a range of colortemperature.Glare is a critical phenomenon often associatedwith the use of LEDs. Satisfying conditionsof visual comfort cannot be reachedwhen sources of very high luminance are inthe field of view. This is the case for “naked”high power LEDs with luminance levels measuredin millions of cd/m2 (nit). Naked LEDsor LED arrays (products with insufficientoptical design) may present visual risks.Safer products with better optical designscan still exhibit discomfort glare, which isnot very well characterized by the standardUGR (unified glare ratio). Its calculationmethod fails when applied to a multitude ofsource points such as an LED array.LED products are very thermally sensitive.LED junction temperature critically affectslight output and color, as well as life expectancy.Many LED products are designed tobe integrated in walls, ceilings or floors, andthese elements are often very well insulated(acoustically and thermally). This meansthat heat generated by LED products mightnot properly dissipate. Generated heat caneven endanger the integrity of building elements,causing for example cracking ofmaterials or deterioration of sealants, allowingmigration of humidity.CITADEL consortiumThe CITADEL consortium is formed byseveral public research laboratories, publicinstitutions and a major lighting company.The partners have complementaryskills and each specializes in a key aspectof LED lighting and building integration:CSTB: Centre Scientifique et Techniquedu Bâtiment (Centre for Building Scienceand Technology), Grenoble, France. Projectleader. In charge of photometry ofluminaires, building integration, agingprotocols, risk analyses and effective lifeexpectancy, life cycle analysis.LASH: Laboratoire des Sciences del’Habitat (ENTPE and CNRS), Lyon. Buildingintegration (visual aspects), light qualityindices, photo-realistic simulations,experiments on subjects, total cost ofownership.CEA-LETI: Grenoble. Microelectronicsexpertise on LEDs, degradation and breakdownsmechanisms of chips/packaging.LNE: Laboratoire National de Métrologieet d’Essais, Trappes. Traceability of measurements,design and construction of highpower LED standard devices.LAPLACE: University of Toulouse andCNRS, Toulouse. Expertise on electronicsaspects of LED lighting products (powersupply and controls). Accelerated aging ofLEDs and LED modules.Philips Lighting, Luminaire division, Miribel:Philips Lighting is committed to providingthe CITADEL partners with therequired product data (bill of materials,industrial processes, etc.) necessary to performlife-cycle analyses and environmentalimpact studies. ◀Footnote: CSTB, LNE, LAPLACE and Philips areactively involved in national and international normalizationactivities (AFNOR in France, CEN inEurope, CEI and CIE worldwide)12 APRIL 2009 LEDsmagazine.comPrevious Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | Next PageABE FMaGS

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | Next PageABE FMaGSAlthough LED lighting products sold inEurope bear the CE label, electrical compliancemust be thoroughly checked beforeinstallation. CE marking is neither a certificationnor a quality mark. It is based ona self-declaration procedure, relying ontests carried out by the manufacturer orthe import company on a limited numberof chosen samples. Numerous low-cost LEDlighting products exhibit very bad power factors,introduce unacceptable harmonic distortionsin the mains current, and generatehigh level of electromagnetic fields.As the American program CALiPERrevealed, specifications given by somemanufacturers are often misleading, especiallywhen dealing with LED substitutionlamps (designed to replace incandescentor fluorescent lamps). Anyone responsiblefor prescribing LED solutions in a buildingproject should first send the productsto an independent laboratory for objectivemeasurements.Research carried out in CITADELThe objective of CITADEL is to promote theoptimal integration of LEDs in buildingsthrough research, with a view of supplyingcrucial information to all those concerned bylighting. The goal is to fully characterize LEDlighting products, keeping in mind the specificneeds of buildings and their occupants.Research is necessary to provide unambiguouscharacterization techniques (optical,thermal and electrical metrology traceableto national standards). At the moment,there is a lack in Europe in the field of normalizationrelated to the measurement ofLED luminaries. (In the US, IESNA has providedLM-79 and LM-80 standards that specificallyconcern LED lighting products.)Research is also important in order todetermine the complete set of relevant performancecriteria (quality of light, visualcomfort, electrical parameters, energy-efficiency,and thermal aspects) in buildings.The degradation of these criteria will givethe true value of the lifetime of LED lightingproducts. This very important aspect will beinvestigated by defining the most appropriateaging methods, using climatic testing(accelerated aging) and endurance testing(ON-OFF cycles, voltage variations, etc).The optical and electrical measurementmethods will be devised in such a way asto supply results that present the true performanceof LEDs at their real workingtemperature. Aging procedures will thenbe developed depending on the usage frequencyof the products and the environmentalfactors which act upon them. Applyingthese procedures will enable us to analyzeand identify, while adhering to a rigorousmethodology, the diverse physical mechanismsof the LED breakdown. These stepsof physical experimentation will allow usto determine and optimize the life expectancyof LED products and establish thetotal lighting cost. The CITADEL projectwill also involve analysis of LED productlife cycle in order to ascertain their environmentalimpact during manufacturing,use and end-of-life.Primary goals of the CITADEL program• Identify the requirements and constraintsleading to a successful integration of LEDlighting product in buildings.• Compare existing and recently proposedindices for describing quality of light (e.g.color rendering index) and visual comfort(e.g. UGR or unified glare ratio). Build newcriteria adapted to LED lighting systems.• Establish reliable methods for physicalcharacterization of LEDs and LED-basedluminaries (optical, thermal, electricalaspects).• Determine accelerated aging protocols (climaticand endurance testing) based on reallifeusage and solicitations met in buildingapplications (indoor and outdoor).• Better understand the degradation andbreakdown phenomena observed in thecourse of the product lifetime.• Determine effective life expectancy ofcomplete LED lighting systems based ona multi-criteria risk analysis.• Provide tools for estimating total cost ofLED lighting solutions.• Perform life-cycle analysis of a limitednumber of well-known, commerciallyavailableLED lighting systems.The research carried out in the CITA-DEL project will help French laboratories toqualify commercially available LED lightingproducts. A certification and labeling activitywill be created during the course of theresearch program._____________________LEDsmagazine.com APRIL 2009 13Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | Next PageABE FMaGS

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Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | Next PageABE FMaGSshow report | STRATEGIES IN LIGHTLighting on track to provide brightfuture for LEDs marketThe LED lighting market continues to generate positive vibes for the industry, as HASSAUN JONES-BEYand TIM WHITAKER found out at the 10th annual Strategies in Light conference.Strategies UnlimitedThe mood was buoyant at Strategiesin Light 2009 despite predictionsthat the overall LEDs market couldfall by 5% in 2009. While some applicationsfor LEDs, such as automotive lightingand mobile phones, have been badly hitby the current recession, the lighting sectoris in good health. LEDs continue to penetratean increasing range of lighting applications,with greater use of white LEDs inareas such as street lighting and even indoorillumination.At Strategies in Light, held February 18-20,2009 in Santa Clara, California, attendeesand exhibitors were optimistic about thepotential for growth in the lighting market.The 2009 event, in its 10th year, is organizedby market research firm Strategies Unlimitedand supported by LEDs Magazine as theflagship media sponsor. There were morethan 2000 registrants this year, up by morethan 33% over 2008.A new parallel session, the LED LightingFixture function(Task light, decorative,outdoor, wet environment...)Regulatoryrequirements(UL, IES, ANSI,Energy Star,Title 24...)AestheticsDecision flowLED light engineFixture designTechnical features(Color, light output...)TestingTrack,was particularlywellattended, drawing in architectsand lighting designers to contributeto the discussion. “Ifthere is one thing to take awayfrom this track, it’s that LED lightingis aboutmuch moreOpticsDriversThermalmanagementFIG. 1. LED lighting is about much more than just LEDs, anddesigning a successful LED fi xture involves a series of keydecisions.HASSAUN JONES-BEY is a contributing editor and TIM WHITAKER is editor of LEDs Magazine.LED-Linear GmbH, an exhibitor at SIL2009, won a Recognized award inthe Next Generation Luminairescompetition (see p26) for Xoolux.This low-profi le (0.94 x 1.49-inchcross section) IP54-protectedLED luminaire can be usedfor undercabinet, task anddisplay case lighting, and hasa simple connection and railmountingsystem for easyinstallation.than just LEDs,”said Vrinda Bhandarkar,senior analystat Strategies Unlimitedand the opening speakerof the track (see “Analyzingthe LED lighting fixturesmarket” sidebar).“If the LED isn’t designedwell into the fixtureto properly throw thelight, if the drivers aren’tdesigned to be efficient,and if the thermal propertiesare not matched to the LED design, thelight fixture won’t deliver the efficiency andlifetime promised.” (See Fig. 1.)Market forecastThe main conference was opened by RobertSteele of Strategies Unlimited, who presentedhis annual high-brightness (HB) LEDmarket review and forecast. Steele said themarket for packaged HB-LED devices grewby 11% in 2008, but is likely to contract by 5%in 2009. If this happens, it will mark the firstLEDsmagazine.com APRIL 2009 15Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | Next PageABE FMaGS

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | Next PageABE FMaGSshow report | STRATEGIES IN LIGHTLutron showcased its Hi-lume LED driver, a universal-voltage dimmingdriver that provides LED dimming from 100% to 1% of total light output.The driver can be used in meeting rooms, corridors, restaurants, hotels,and many other areas where dimming performance and energy effi ciencyare valued.time the overall market has declined sinceStrategies Unlimited started to publish dataon the HB-LED market in 1999.Steele gave a historical perspective onthe HB-LED market, which was a mere $820million in 1999. Between 1999 and 2008, saidSteele, the HB-LED market grew by a factorof 6.2, reaching $5.1 billion last year. Yearon-yeargrowth has varied dramatically;approximately 50% growth in 2000, 2002and 2003 was driven by strong demand inthe mobile phone market, but in betweenthe market saw virtually zero growth in2001 as the tech sector went into recession.The growth rate dropped to below 10%in 2005, but has since risen gradually, andin 2008 the market increased by 11% comparedwith 2007. However, the fourth quarterof 2008 showed signs of market deterioration,particularly in the automotive lightingand mobile phone sectors.Unit sales of LEDs grew by more than 25%in 2008, reaching 48 billion units. Mobileappliances remained the largest application,with 43% of the overall market, comparedwith 9% for lighting (see Fig. 2). Themobile appliances sector showed the firstpositive growth (8.3%) since 2004 becauseof the growth in non-phoneproducts (smartphones, MP3players, laptop PCs, GPS, digitalcameras). Not surprisingly,the highest growth sectorwas lighting, up 39% over2007, although the sector onlyreached $460 million.Looking forward, saidSteele, the “negative economicenvironment and bleak outlookfor many LED end-usesectors indicate a lower marketin 2009.” Visibility is verylimited, and conditions couldworsen. “Recovery could bedelayed beyond 2010,” saidSteele. “The only ‘bright spots’are backlights for LCD TVs,and of course lighting.”Steele expects the penetration of LEDsinto the lighting market to continue into2009, but with a lower growth rate of 17%,compared with the level of 35% that wasforecast previously. In the longer term, thereis a positive outlook for the lighting sector,and Steele said that the market will get backon track, following the economic recovery.The prediction that the overall market willdecline by 5% in 2009 includes a conservativeforecast for growth in LCD TV backlights.This is the most uncertain of all LEDapplication sectors; when this application isexcluded, the remainder of the HB-LED marketwill shrink by 10% in 2009.Looking further out, Steele expects growthto resume in 2010, assuming the economyas a whole recovers. Between 2008 and 2013,the compound average annual growth rateis predicted to be 19.3%, with the marketreaching $12.4 billion in 2013.Illuminating consumer preferenceLED market penetration for lighting applicationsremains small and highly fragmentedinto numerous application niches, said BobSteele, and architectural lighting at 43% ofthe lighting market represents the largestniche. But the highest growth applicationsin 2008 (cumulatively accounting for 16% ofthe SSL market) were outdoor area, replacementlamps, commercial/industrial andentertainment.Numerous technology improvements duringthe last decade have contributed to therapid growth of LEDs in the lighting market,including development of high-power LEDs;increased luminous efficacy by a factor of6.7 for cool-white LEDs; and introductionof warmer whites mid-decade, which havedoubled in luminous efficacy since 2004,Steele said. And most of the major solidstate-lightingplayers have 100-lumen productson the market. As a result, the industryfocus is shifting away from technologicalissues such as achieving higher light outputand increased efficiency, to customer satisfactionissues, said Erik Milz, strategicmarketing manager with Philips Lumileds.These include the quality and uniformityof white light, the elimination of binning,enabling simplified system design, phosphorsystems, forward voltage and supply chainsafety (reliability).The three primary LED aspects to consider— flux, forward voltage and color — createa 3-dimensional (3-D) binning matrix, whilethe lamp matrix for luminaire manufacturersincludes factors such as shape, direction,style, warm or cool coloration, and power.CCFLs took a step towards improving energyefficiency and also simplifying the matrix,Milz said. But, except for places like Californiawhere government support encouragestheir use, CCFLs remain a small, single-digitpercentage of the market becauselighting performance is not predictable, orperhaps predictably unpleasing: “We don’twant solid state lighting to make the samemistake,” he said.Outdoor area lightsPerhaps nowhere is the story more dramaticallytold than in beleaguered municipalitiestrying to keep their street lightson during hard economic times. George16 APRIL 2009 LEDsmagazine.comPrevious Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | Next PageABE FMaGS

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Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | Next PageABE FMaGSshow report | STRATEGIES IN LIGHTCourtesy of Strategies UnlimitedSignals1%Lighting9%Automotive15%2008 HB-LED marketTotal market: $5.1 billionOther15%Signs/ displays17%Mobileappliances43%FIG. 2. Mobile appliances remained the largest HB-LEDapplication in 2008, although Lighting showed the mostrapid growth.Woodbury, director of energy services withRepublic ITS, provided the perspective of aformer public works director turned consultantwho has completed conversions ofover 45,000 street lights. He warned of thebad taste that can be left in the mouth ofa municipality that invests in LED streetlights and gets stuck with disappointingperformance.“In terms of reliability, we have to get thebad product out of there, and get reputablecompanies in there with good products,”Woodbury said. He talked about theimportance of avoiding “LED hype”when promising energy savings,maintenance savings and evenlife cycle costs, which for variouspractical reasons can turnout to be disappointing oncelighting is installed.All of that said, LED streetlights can be quite successful andare becoming more so with time.Currently, LEDs are bright enough forstreet light applications, but are still on theexpensive side both initially and in terms ofactual energy savings, he said. In addition,LED performance data needs standardization,and lighting industry guidelines needto be developed to account for factors suchas light measurement under mesopic conditions.However, Woodbury expects thecurrent rapid pace of technology change toaddress such issues significantly in the nextcouple of years, saying, “LEDs are gettingthere.”Replacement lightingA key factor for LEDs inreplacing conventionallight bulbs is the ongoingtransition from LED bulbs(standard LED componentsarranged to mimic conventionalbulb shapes) to SSLsources (lighting fixturesdesigned specifically forLEDs), according to MarkMcClear, business developmentdirector with Cree. “Abulb is an adaptor, a bridgeto the real LED fixtures,” hesaid. “But we’re stuck with itfor now.” LED bulbs potentiallyprovide longer life andmuch better efficacy than their conventionalcounterparts, but thermal limitations inherentto the form factor will eventually drive atransition to SSL sources.For instance, in attempting to simulatean MR16 using an LED bulb, McClear andcolleagues at Cree realized that since theycould only drive the LED device at 5 or 6 W,the performance was only equivalent to a20 W MR16 at an industry-standard 3000Ka)color temperature. “35W might be availablelater,” he said. “But 50W does not look possibleusing standardcomponents.” Theyfound similar limitationsin attempts tosimulate both A19 andPAR 38 bulb designs.Not everyone agreed withMcClear’s conclusions about thermodynamiclimits to LED bulb brightness.Densen Cao, president of CAOGroup, described 3-D LED-basedlight sources for direct replacementof traditional incandescent lamps instandard sockets, such as candelabra,S14, 1156 and others (Fig. 3). The 3-DLED and driver element essentiallytakes the place of the filament in astandard bulb structure. Ten and 25W replacements are currently availableand the company expects to havedirect replacements for the majorityof bulbs (40 and 60 W) within the nexttwo years. “The key is not the LED butheat management,” said Cao.Commercial and industrial lightingCurrently, LED bulbs can use inherentdirectionality to improve their performancewith respect to conventional lightingsources, said McClear. LED bulbs arehighly suited for refrigerated high-bayapplications because they have alreadyachieved energy parity with the most efficientalternative — T8 fluorescents — butdo not suffer from cold temperature sensitivity,as fluorescents do. Initial costb)FIG. 3. CAO Group’s a)Dynasty S14 and b) 1156LED bulbs are designedas direct replacementsfor incandescents, andcontain a replaceable LEDsource with a 360-degreebeam pattern.18 APRIL 2009 LEDsmagazine.comPrevious Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | Next PageABE FMaGS

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | Next PageABE FMaGSshow report | STRATEGIES IN LIGHTFIG. 4. Using LED task lighting forworkstations combined with individualcontrols, the California Department ofMotor Vehicles in Sacramento was ableto lower the ambient lighting levels andalso save energy. See www.fi ____________ nelite.com/about-us/success-stories._________________is still the major hurdle for LEDs in unrefrigeratedhigh-bay lighting, McClear said.But improvements in efficiency throughfactors such as optical directionality controlmay make LEDs a compelling choicefor hi-bay applications in general in thenext 3 years.Citing 10 billion square feet of commercialoffice space in the US alone, Terry Clarke,CEO of Finelite, described his company’ssuccessful approach to reducing lightingpower density by 50% and achieving overwhelmingcustomer acceptance, while keepinginstalled costs the same as with conventionallight sources. The first stepin Clarke’s process is to designthe task lighting, which iscurrently the last stepin most office lightingdesign situations.LED task luminairesalready have conventionalfluorescent taskluminaires beaten,not only in energy efficiencybut also in consumeracceptance, he© Gregory Blore PhotographyAnalyzing the LED lighting fixtures marketOpening the LED Lighting Track at SIL 2009, Vrinda Bhandarkar of Strategies Unlimitedestimated that the total global market for LED lighting fi xtures will exceed $5 billion in2012. Bhandarkar is the author of a new report entitled “LED lighting Fixtures — MarketAnalysis and Forecast.” As LED lighting extends beyond single color and color-changingapplications into general illumination,the market will grow at a compoundannual growth rate (CAGR) of 28%between 2008 and 2012 (see graph).However, many challenges face LEDfi xture suppliers, for example high initialcost; product quality and reliability; the(relative) lack of standards; the pooravailability of high-performance warmwhiteLEDs; and competing lightingtechnologies.Through 2007, LED lightingapplications included niche marketssuch as exit signs, architecturallighting, accent and decorative lightingand entertainment lighting, many ofwhich used red, green, and blue LEDs.LINKS AND DATESStrategies in Light: www.strategiesinlight.comLED Japan/SIL Japan 2009: September 16-17, YokohamaSIL 2010: February 10-12, 2010, Santa Clara, CaliforniaVideo clips from SIL 2009: www.ledsmagazine.com/videoNews from SIL 2009: www.ledsmagazine.com/features/6/1/1Strategies Unlimited6543210LED lighting fixtures market($ billion)2007 2008 2009 2010 2011 2012LED lighting market will grow at a CAGR of28% between 2008 and 2012.However, white LED fi xtures have begun to capture a strong market position in selectedapplications such as consumer portable lighting (e.g. fl ashlights, headlamps) andsolar landscape lighting, and more recently have begun to be used on a limited basisin applications such as retail display lighting, commercial and industrial lighting, andoutdoor area lighting. In 2008, white LED fi xtures accounted for just over 50% of thetotal LED lighting fi xture market, said Bhandarkar. The penetration of white LED lightingfi xtures into general illumination applications will accelerate when such fi xtures offerquantifi able energy and cost savings relative to the use of conventional light sources.Bhandarkar described a series of assumptions built into the market forecast. Theseinclude continuous improvement in the effi cacy of LEDs and LED fi xtures; price erosion;and incorporation of standards into codes and practices in 2009 and beyond. Alsoassumed is a continuing focus on energy effi ciency, including fi scal stimulus by variousgovernments to provide investment in infrastructure. ◀said. Fluorescent task luminaires produce somuch excess light and glare that 80% of peopleworking in office situations simply turnthem off. So LED task lighting reduces theenergy budget, not just for task lighting butfor the entire lighting design, because ambientlighting no longer has to be bright enoughto also provide task lighting (Fig. 4).However, warns Clark, “the changeoveris extraordinarily difficult. You need to geteveryone on board: building owners, designprofessionals and contractors.” Evidently,as is still true with cell phones, the ultimatesuccess of LED technology in general illuminationapplications will depend on a lotof talk.LEDsmagazine.com APRIL 2009 19Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | Next PageABE FMaGS

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Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | Next PageABE FMaGSlighting | DIMMINGControlling consumers' expectations ofLED lighting: why dimming is so importantManufacturers of LED lighting products need to consider the control optionsfor their products and understand the applications in which their productswill be used, say CHRIS SALVESTRINI and AMANDA BEEBE.The US Census Bureau estimated thatthere are over 75 million owner-occupiedhomes (2007) and almost 5 millioncommercial buildings (2003) in the UnitedStates. Many of these buildings, both commercialand residential, already have dimmersinstalled. These existing dimmers are controllinga multitude of light sources, from incandescentto fluorescent and now LEDs, whichis why the capacity to dim must be designedinto an LED product from the beginning.Consumers, professionals, teachers and occupantsexpect to have control of their lights,and LEDs must meet this expectation if LEDlighting solutions are going to succeed.Why dim?The story of why to dim your lights has beenaround for a long time, and many peopleknow that lighting controls can improvepersonal comfort, increase occupant productivity,extend luminaire lifetime andsave energy. However, with the introductionof new lighting technologies it seemsthat this story is often forgotten, at leastuntil the market is full of disgruntled consumersand building occupants.The LED industry is heading toward thesame negative experiences as the screw-inCFL industry and needs to correct its coursenow, before consumers become averse toLEDs. LEDs are a promising new technologythat will eventually influence, and evenchange, the lighting industry. However, theywill not reach that point as quickly as theirpotential suggests unless the industry beginsto pay attention to consumer expectations.a)b)FIG. 1. a) Forward phase control and b)reverse phase control. Light blue showswhen the control is open (off) and darkblue shows when the control is closed (on).So what are those expectations?In the home, consumers expect their lightsource to act like the incandescent lamp thatthey have lived under for 100 years, meaningthat they want two things — color, and ambiancecreated with dimming. The screw-in CFLlamp continues to fall short of expectationsbecause it has failed to meet either of these criteria.Some LED makers understand the desirefor the perfect color temperature and are creativelyusing technology to provide the exactcolor of light that a consumer wants. However,these same manufacturers do not understandthat dimming is equally as important as color— consumers want just the right amount oflight for whatever they are doing.Commercially, the lights are on in a buildingto allow people to be productive. Toooften we think of energy-saving techniquesthat are only about turning the lights off.However, this tactic does not apply when abuilding or space is occupied, which makesthe ability to dim an equally importantenergy-saving technique.Dimming can be a manual choice by auser, a tuning decision by a building owner,or an automatic change due to the amountof sunlight. However, no matter which dimmingtechnique is used, it will save energy.While additional energy savings for anLED (which already save energy by replacinga 100-W incandescent with a 25-W LEDarray) may seem less important, consumersdo not agree. They are looking for every possibleway to save energy, and dimming willsave an additional 20%-30% on average withoutsacrificing comfort.In addition to energy savings, the occupantsof these buildings are the same peoplewho expect control in their homes, so whyshould they sacrifice this control at work?Dimming allows for increased productivity,which is paramount in a working environment.Everyone has different visual abilitiesand comfort levels, and being able to optimizeyour environment goes a long way.Now that you understand why dimming isimportant, you should also know that simplybeing “able to dim” is not good enough.Dimming is a quantifiable term and it shouldalways be associated with a dimming range,such as 100% to 1% of light output, as wellas other terms that describe that range (e.g.smooth and continuous). An LED array manufacturerwould never merely state that theirproduct “provides light” because that doesn’ttell the user anything, and the same goes forsaying a fixture is simply “dimmable.”AMANDA BEEBE is LED product manager and CHRIS SALVESTRINI is a senior design anddevelopment engineer with Lutron Electronics (www.lutron.com).LED control typesOnce you have accepted that high-qualityLEDsmagazine.com APRIL 2009 21Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | Next PageABE FMaGS

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | Next PageABE FMaGSlighting | DIMMINGDimming: critical term definitionsMeasured vs. perceived light:Measured light output is the quantifi ablevalue of light measured by a light meteror similar device. This is the dimmingpercentage indicated on LED productspecifi cation sheets. Perceived light is theamount of light that your eye interprets dueto dilation. The eye’s pupil dilates at lowerlight levels, causing the amount of perceivedlight to be higher than measured (e.g. 20%measured = 45% perceived). The equationfor determining perceived light is to take thesquare root of the measured light percentage(e.g. = 0.447) — see fi gure.Pop-on:If the voltage at which a light source beginsoperation is higher than the voltage of thedimmer’s lowest setting, then the lights willinitially “pop-on”. This means there will be asection of the dimmer that will not turn onthe light until suddenly the light “pops-on.”Drop-out:If the voltage at which a light source stopsoperating is higher than the lowest settingon the dimmer, the light source will turn offbefore the dimmer has turned off. The lightswill effectively “drop-out” before the slideron the dimmer reaches the bottom.Flicker:Flicker is the unexpected modulation oflight level that is visible to the humaneye. Flicker can be caused by multiplefactors, including: line noise, control noise,circuit noise, component tolerance, andcircuit design. Flicker can be continuous(happening all of the time), or intermittent(only happening some of the time).Smooth and continuous:Smooth and continuous describes theexpectation of performance based onthe public’s knowledge of incandescent10080601% Architectural dimming5% Hi performance dimming10% Lighting managementdimming401 5 10 200 102232405060708090100MeasuredPerceived light (%)light (%)Determining perceived light. Source:IESNA Lighting Handbook, 9th Edition(New York, 2000), 27-4.dimming. A proportional change in control(dimmer) position should be refl ected by anequal change in light level. There should beno abrupt change in light level as the lightsource is being dimmed.Dead travel:Dead travel is the amount of change in thecontrol before there is any change in thelight source. In a vertical slide dimmer, ifyou can slide the dimmer halfway downbefore the light starts to dim, there is 50%“dead travel” on the dimmer. ◀ ____________ 22 APRIL 2009 LEDsmagazine.comPrevious Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | Next PageABE FMaGS

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Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | Next PageABE FMaGSlighting | DIMMINGdimming is an essential part of any goodlighting solution, and understood some ofthe critical terms (see p. 22), the next step isto gain awareness of what types of dimmingcontrols currently exist. Selecting the appropriatecontrol depends on the light source,the degree of flexibility needed in the space,and whether an interface (ballast, driver, ortransformer) is needed. Below is an overviewof each of the main control types that existtoday, indicating where they are most commonlyused:a) Two-wire controlTwo-wire control is the most commonlyused control method today, and simply indicatesthat there is a single wire between thedevice and the light source. It is the controltype of a standard light switch, where powercomes into the switch through one wireand leaves through another. Within twowirecontrol there are two different controlmethodologies:i) Forward phase control: The more prominentof the two, it is also called leading-edgecontrol. In this control scheme the controlbegins each half-cycle in the open positionand then turns on and remains on for theremainder of the half-cycle. This is illustratedin Fig. 1a, where the light blue showswhen the control is open (off) and the darkblue shows when the control is closed (on).This method works well for controllinginductive loads, and as a result forwardphase control is required to control magneticlow-voltage lighting transformers. Itis also the dominant method used to controlincandescent lights.ii) Reverse phase control: Also called trailing-edgecontrol, it is used to control electroniclow-voltage light sources. As shown inFig. 1b, this is the exact opposite of forwardphase control. While this control type can beused on incandescent lights it typically providesthe ideal control signal for capacitiveloads, such as many LED drivers.b) Three-wire controlsThree-wire controls are primarily used tocontrol fluorescent light sources becausethe power requirements of the ballast willnot impact the dimming performance ofthe light source. One of the wires providespower to the light source whenever it is on,regardless of the light level, while the otherwire provides the control signal that setsthe light level at which the fixture should beoperating.In all of the following approaches (0-10V,DALI, and DMX), the control exists on an isolatedlow voltage link from the power to thelight source. One of the benefits of this is thatthe system can be interfaced with a varietyof other devices such as occupancy sensors,daylight sensors, and infrared receivers.c) 0-10V control0-10V control is an analog control that setsthe voltage to the light source between 0V(minimum light output) and 10V (maximumlight output). IEC standard 60929 specifiesexactly what control requirements exist forthis control type.d) Digital controli) DALI: This Digital Addressable LightingInterface control standard, which emergedfrom Europe, allows for digital control ofseparate fixtures. This added level of controlprovides increased space flexibility,especially in commercial spaces.ii) DMX: This digital control type camefrom theater lighting control, and allowsfor multiple channels of light (both colorand intensity) to be controlled. It is typicallyused when trying to achieve complicatedlighting effects such as LED colormixing.ConclusionLEDs are a promising new light source forgeneral illumination, but they will neverexcel unless manufacturers understandconsumer expectations. Having control is abasic human desire, and lighting is no exception.Stereos would be limited without volumecontrols; ovens would be dysfunctionalwithout temperature controls, so why shouldlights be used without controls?24 APRIL 2009 LEDsmagazine.comPrevious Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | Next PageABE FMaGS

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Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | Next PageABE FMaGSfocus onLuminairesThe winners of the 2008 LED Next GenerationLuminaires design competition were announced atStrategies in Light in mid February. The competition issponsored by the US Department of Energy (DOE), theIlluminating Engineering Society of North America(IESNA), and the International Association of LightingDesigners (IALD). Of the 68 entries submitted, threewere chosen as “Best in Class” in the market-readycategory and a further 19 were “Recognized.” Fiveother products were selected as “Noteworthy” in theemerging products category.MORE WINNERS: www.ngldc.orgPhotometric testing was carriedout by independent testinglaboratories using IESNA testmethod LM-79-08. Where thisdata was lacking, luminaireswere tested through DOE'sCALiPER testing program.Best in Class“Immersion” byGE Lighting ▶GE says that its ImmersionLED jewelry displaycase lighting brings outmore sparkle than competingfluorescent systems.Light output:1494 lm. Power: 42.5 W.Efficacy: 35.1 lm/W. CCT:3515K. CRI: 72. Lengths:from 24–72 inches.www.gelighting.com“LED Pendant” byTech Lighting ▶Tech Lighting has introducedover 40 decorativependants that utilizea 5.8-W LED module — developed withLighting Science Group — that is easilyfield replaceable and the heat sinkremains with the fixture. Light output:200 lm. Power: 5.6 W. Efficacy: 35.7 lm/W.CCT: 2968. CRI: 80.www.techlighting.com“C-Series LED High Bay” by Albeo Technologies Inc.This LED high bay luminaire, using TEMPRthermal management technology, is a lowmaintenance,energy- efficient alternativeto traditional HID or high-intensity fluorescentlight fixtures. Light output: 18,268 lm.Power: 362 W. Efficacy: 50.4 lm/W. CCT: 5000. CRI: 75(CCT and CRI values have not been independently verified.)www.albeotech.com▶Recognized“Calculite LED downlight”by LightolierThese 4-inch LED downlights useLightolier’s remote phosphor technologyto redefine how light from blue LEDsis converted to white while providinggood glare control and consistent color.Light output: 1032 lm. Power: 20.1 W.Efficacy: 51.3 lm/W. CCT: 3015. CRI: 80.www.lightolier.com▶26 APRIL 2009 LEDsmagazine.comPrevious Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | Next PageABE FMaGS

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | Next PageABE FMaGS▶“STEP03” by Winona LightingThe STEP03 series of step lights withthree different styles provides good lateraldistribution, integral drivers, andthe flexibility to modify. Light output:454 lm. Power: 21.7 W. Efficacy: 21.3lm/W. CCT: 2996 CRI: 71.www.winonalighting.com◀ “AZARA” byJournée LightingAt the heart of the AZARA’s retro,yet functional styling is Journée’sreplaceable Sprocket LED lightengine. AZARA’s housing performs asan active heat sink. Light output: 249 lumens. Power:6.9 watts. Efficacy: 36.1 lm/W. CCT: 2911K. CRI: 85.www.journeelighting.com◀ “LED72” by MP LightingThe 12 x 1.2 W LED72 works well foraccent lighting and general directionalillumination and mounts to a standardj-box or MP Lighting rail systemwith a remote driver. Light output:373 lm. Power: 18.3 W. Efficacy:20.4 lm/W. CCT: 2953. CRI: 96.www.mplighting.com“LR24” by Cree LED LightingThe LR24 2 x 2-foot architectural layinis designed for new construction andretrofit applications inoffices, schools, hospitals,and retail environments.Light output:3237 lm. Power: 44.7W. Efficacy: 72.4 lm/W.CCT: 3491. CRI: 89.www.creelighting.com▶“Evoke 2.9” by Amer Lux Lighting SolutionsThe Evoke 2.9 LED, available in round or square aperture,features a field serviceable seven-diode cluster measuring1.25-inches (dia.) and produces uniform light in a 60° beamspread with negligible heat and UV output. Light output: 913lm. Power: 25.1 W. Efficacy: 36.3 lm/W. CCT: 2700. CRI: 83.www.amerlux.com▶LEDsmagazine.com APRIL 2009 27Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | Next PageABE FMaGS

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Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | Next PageABE FMaGSstandards | PROGRESS REVIEWWhy 2008 was the Year of LED StandardsIn the fi rst of a series of articles, KEVIN DOWLING explains the importance of standards for LEDlighting and looks at the signifi cant progress that has been made so far.In an era of rapid performance improvement,2008 is likely to be rememberedas the Year of LED Standards, which area critical ingredient in the market use andadoption of LED lighting technology. Lastyear saw the publication of several performancestandards as well as guidelines thatrequired the use of these standards — ineffect, standards based upon standards. It isa good start, but only a start. However, manyother standards are in process, and remarkableprogress has been made.Importance of standardsStandards are very important for severalreasons. Without standards, comparison isdifficult or impossible. In many cases productspecifications are not traceable to anauthoritative reference, making all such datasuspect at best, and disingenuous at worst.Furthermore, some manufacturers playspecification games; this is unacceptable.Without standards, customers and specifiersare uneasy about specifying and purchasingLED-based products. Emplacing standardslessens this issue and, as this communitygrows comfortable with the standards-basedapproach, they will specify more, not less.The market grows; adoption increases andthe results benefit both users and manufacturers.Subsequently, LEDs can also providesocietal benefits in terms of energy savedand carbon footprints reduced. This chain ofreasoning is not to be taken lightly. Withoutstandards, LED lighting will become a “WildWest” of disorder and confusion.The US Department of Energy’s CALi-PER program reveals that many LED lightingproducts already suffer from a “truthin-advertising”issue with regards topublished specifications versus actualtesting laboratory measurements. Someuse the performance of an independentdevice (i.e. the LED itself) as a proxy forthe performance of the fixture. Unsurprisingly,the real performance doesnot live up to advertised claims. Withoutdwelling on all the reasons why, it isclear that the numbers are determinedthrough means that are both inconsistentand even irrelevant. It comes downto trusting the numbers; consistent andpractical testing methods are needed.Standards emerge in 2008So what happened in 2008 to improvethis situation? Through the solidstatelighting (SSL) committees withinthe National Electrical ManufacturersAssociation (NEMA), the AmericanNational Standards Institute (ANSI) and theIlluminating Engineering Society of NorthAmerica (IESNA), we crafted three importantstandards milestones — ANSI C77.78, IESNALM-79 and IESNA LM-80 — see “Standardsfinalized in 2008”. Additionally, the IESTesting Procedures Committee worked ondefinitions around LED systems to providea consistent vocabulary around this technology(IESNA RP-16 Addendum A).ANSI C78.377-2008: ChromaticityThis standard defines eight bounded regionsthat identify particular color temperaturevalues for white LED sources. These regionswere chosen, after much discussion, to bebased upon similar regions used for compactfluorescent lamps (CFLs), which are definedKEVIN DOWLING is the VP of innovation at Philips Color Kinetics (www.colorkinetics.com) andhas been active in SSL for over 10 years. He founded and chairs the IES SSL Committee and theNEMA SSL Committee, and is a past Chairman of the Next Generation Lighting Industry Alliance.Standards finalized in 2008Chromaticity: ANSI C78.377-2008“Specifi cations for the Chromaticity of SolidState Lighting Products”Luminous Flux: IESNA LM-79“Electrical and Photometric Measurements ofSolid-State Lighting Products”Lumen Maintenance: IESNA LM-80“Measuring Lumen Maintenance of LED LightSources”Defi nitions: IESNA RP-16 Addendum A“Nomenclature and Defi nitions for IlluminatingEngineering” ◀by 7-step MacAdam ellipses. One additionalregion, 5700K, was added for LEDs to providea continuum of color temperature ranges.The use of these definitions for LED colortemperature regions is a good beginning,and LED manufacturers are already providingLED binning that is ANSI-compliant fortheir customers.IESNA LM-79: Luminous fluxLM-79 provides methods of determiningthe lumen output of LED luminaires andintegrated LED lamps. The products mustrequire only line voltage or a DC power supplyto operate. LM-79 does not cover SSLproducts requiring external operating circuitsor external heat sinks, such as LEDchips, packages, and modules. It also doesnot cover fixtures designed for SSL productsthat are sold without a light source.Traditionally, photometric measurementsare made separately for lamps and luminairesusing different test methods. However,for many SSL products, LED lamps cannotbe separated from luminaires, and noneLEDsmagazine.com APRIL 2009 29Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | Next PageABE FMaGS

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | Next PageABE FMaGSstandards | PROGRESS REVIEW______________of the existing standards for lamps or luminaires are directly applicableto SSL products. What this means is a method of measurementnot commonly used — absolute photometry.Under a relative measurement, the most common form of lightoutput determination, the luminaire under test and the lamp(s) aremeasured separately. Then the luminous intensity distribution dataare normalized by the total luminous flux of lamps used in the testedluminaire. Under the absolute method, the luminous intensity distributionof a luminaire is measured without separate measurementof the lamps.Section 9.3 of LM-79 details the measurement and the Annex goesinto the reasoning behind the requirement for absolute photometry.LM-79 recommends using an integrating sphere with a spectroradiometer,but other alternatives are provided including a sphere witha photometer and the use of a goniophotometer for measurements.The spectroradiometer returns the full spectral power distributionfrom which several characteristics are calculated, including chromaticity,CCT and CRI. For the goniophotometer, the result may bespatially non-uniform, but must be spatially averaged, weighted tointensity, over the angular range of measurement.Another key difference in photometry measurements for SSLdevices is thermal stabilization, which is determined by repeatedsequences of measurements until the difference over two measurementsis below a specified amount. In LM-79, the unit is stabilizedwhen three readings of light output and electrical power over 30 minutes,taken 15 minutes apart, fall within a 0.5% variation.The combination of the thermal stabilization, absolute photometryand other elements in LM-79 have made for a reliable test methodfor LED light sources.LM-80: Lumen maintenanceLumen maintenance is the gradual fading of the light output from anLED device over time. Many LED product specifications use lumenmaintenance to indicate product lifetime, but this is only one aspectof lifetime and not a complete measure of life. It does not, for example,provide a true measure of reliability. Lumen maintenance does, however,provide an indication of the fading of LED package light outputover time. When properly controlled and thermally managed, manyhigh-brightness LEDs can last many tens of thousands of hours, butwe need a consistent method to provide that information. Hence theneed for LM-80.The causes of this fading are only partially understood, but the primarycause relates directly to heat generated at the junction withinthe LED. It includes materials clouding, which is affected by packageand system design. A number of LED manufacturers, for example,have switched encapsulant material to silicone from epoxy, whichwas prone to yellowing from the light energy.The measurement of lumen maintenance is relatively straightforwardin concept — run the LEDs over a long period of time andmeasure the change in light output. Since it is impractical to measurethese devices for a decade, because they will be surpassed bynew generations of LEDs, some form of prediction or extrapolationis necessary.LM-80 was created for one important reason — to ensure consistency30 APRIL 2009 LEDsmagazine.comPrevious Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | Next PageABE FMaGS

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | Next PageABE FMaGSstandards | PROGRESS REVIEWof the testing regime. LM-80 does not predictlumen maintenance beyond the testingperiod. In the process of creating LM-80, furtherdiscussion around the extrapolationmodel was necessary, but it was importantto get the testing method out so that testingcould begun immediately across a widerange of devices. The more data we have,the more likely it is that we can develop agood prediction model. Another committee,TM-21, is in the process of developing sucha model now.LM-80 measures lumen maintenanceof LED light sources including LED packages,arrays and modules only. It does notinclude luminaires. LM-80 specifies a numberof electrical and thermal measurementssuch as voltage and current (AC or DC levels),voltage waveshape, etc.The case temperature is obtained from a testmeasurement point designated by the manufacturer.A key aspect of LM-80 is the value ofthe temperature measurement levels. Theyinclude 55°C, 85°C and a third temperatureselected by the manufacturer. During testingthe airflow in the region must be minimized,and any specifications for operatingorientation and spacing can be provided bythe manufacturer.LM-80 currently requires 6000 hours oftesting time, which is a long time. Some haveargued that this is too long, but unless a betterway comes along to predict lumen maintenancefrom a relatively short testing timethen there is no means with strong confidencethat provides an accurate measure oflumen maintenance. It is very likely, withouta lot of supporting data, that any predictionmethod will be limited to some multiplier ofthe testing period. The testing interval for thephotometric measurements is a minimum ofLINKSComing in part 2The next part of this article will coverfurther details on LM-80 as well aslooking at the various Guidelines (e.g.Title 24, Energy Star) that call on theStandards described above. The articlewill also look at the impressive array ofstandards that are currently in process,and the need for harmonization on aglobal basis. ◀1000 hours, so that sufficient data points canbe collected for a good sequence from whichtrends can be calculated.Webcast on photometry and standards: www.ledsmagazine.com/features/6/2/15More information and images: www.ledsmagazine.com/features/6/4/1_____________LEDsmagazine.com APRIL 2009 31Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | Next PageABE FMaGS

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | Next PageABE FMaGSILLUMINATION DESIGN SOFTWAREOptimize using the power ofLightTools and SolidWorksLink optical and mechanical design software to accelerate your illumination design process.The LightTools SolidWorks ®Link Module allows you todynamically link SolidWorksmechanical models to LightTools,where you can assign opticalproperties, optimize, and directlyupdate your SolidWorks designs.Optical precision and rapiddesign evaluationsDeliver innovative illuminationsystems withLightTools’ full opticalaccuracy and fast, powerfulanalysis features. Opticalproperties are preservedduring bidirectionalcommunications betweenLightTools and SolidWorksto reduce time and effortduring iterative design.Automatic design refinementLightTools’ integrated optimizationcapability improves systemperformance automatically withalgorithms specially tailored tosolve illumination problems.When you link your SolidWorksmodel to LightTools, you canoptimize parts, assemblies, andoptical components to meet oreven exceed your design goals.Seamless data managementFull parametric interoperabilitybetween LightTools andSolidWorks ensures that allparameter changes in LightToolsare immediately updated inSolidWorks. This integratedenvironment provides your teamwith a collaborative, streamlineddesign process.After 3 iterations, LightTools optimization improved the on-axis intensity by more than 100x.www.opticalres.comCorporate Headquarters: 3280 East Foothill Boulevard, Pasadena, CA 91107-3103 (626) 795-9101Fax (626) 795-0184 E-mail: info@opticalres.com Web: www.opticalres.comOffices: Tucson, AZ | Westborough, MA©2008 Optical Research Associates. LightTools is a registered trademark of Optical Research Associates. SolidWorks is a registered trademark of SolidWorks Corporation.Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | Next PageABE FMaGS

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | Next PageABE FMaGSdesign forum | DRIVING STRINGSAvoiding thermal runaway whendriving multiple LED stringsThe use of a current mirror confi guration and additional circuitry can ensure current balancingthrough parallel strings of LEDs, writes STEVE ROBERTS.An increasingly common method ofincreasing the light output from ahigh power LED cluster is to runparallel strings of LEDs from a single constantcurrent source. But this option is notwithout its hazards. A typical high-power350 mA white LED has a forward voltage(V f) of about 3.3 V, so if a cluster of 10 LEDswere required in an application, connectingall of the LEDs in series would require adriver capable of delivering at least 33 V. Ifthe supply voltage is 24 VDC, then an expensiveboost converter would be required withall the attendant electromagnetic compatibility(EMC) problems it creates.Connecting the 10 LEDs as two strings of5, wired in parallel, requires a 700 mA constant-currentsource but only 16.5 V outputvoltage. This means a low-cost buck converterrunning from 24 VDC can be used.This circuit configuration can be found inmany manufacturers’ datasheets. There is abasic assumption that the 700 mA regulatedcurrent will be shared approximately evenlyacross both strings of LEDs, i.e. each stringof LEDs will see 350 mA of current.However, this is rarely the case. Even ifthe LEDs are all from the same productionbatch and sequentially manufactured, theV fof individual LEDs still has a ±20% tolerance.The tolerances mean that the total V ffor each string can be very different, resultingin significant current mismatch.Overdrive situationA test was carried out using identical SMDLEDs from a single production batch, with10 LEDs connected as two strings of 5 in parallel.Using 1 Ω resistors to help balance outV in = 16~36VDC+V inRCD-24-0.70+V outAnaPWM-V-V outinthe forward voltages, the currents flowingin each string were measured to be 306 mAand 394 mA. The LED driver was still doingits job of correctly — i.e. limiting the currentto 700 mA — but the over-current flowingthrough the second string was seriouslyoverdriving the LEDs.Worse, as the LEDs started to get warm,the combined V fof the higher-currentstring started to decrease. This increasedthe imbalance and more current started toflow through the already over-driven string.The current through the other LED stringreduced as the constant current driver compensated,so they started to cool down andtheir V fincreased.The net result was thermal runaway,with the majority of current flowingthrough one string only, even though theLEDs were mounted on a large metal heatsink. The test was stopped when the currentimbalance was 600 mA to 100 mA.Obviously, if this situation was allowedto continue, the over-driven string wouldeventually fail and then the entire 700 mAwould flow through the remaining intactstring and destroy that as well. And thiscircuit is often given as a recommendedapplication example!What is required is a way of balancing theSTEVE ROBERTS is technical support manager in Europe for RECOM GmbH(www.recom-international.com). He is based in Gmunden, Austria.700mABC337LED1String1LED5BD139347mA1R5680RLED6String2LED10680R1R5Thermallyconnected350mABD139The fi nal version of the current balancingcircuit.currents flowing through the two stringsto ensure that they remain approximatelyequal, even if the combined V fvalues aremismatched. The balancing circuit mustalso continually compensate for changes inV fcaused by changes in the operating temperatureand by aging of the LEDs.Using a current mirrorFortunately, there is a very simple transistorcircuit that will do this job admirably.It is called a current mirror and “reflects”the current flowing through one referencetransistor onto the current flowing througha second transistor. As long as the transistorsare reasonably well matched in termsof their V bevalues, the currents will also bereasonably well matched.In tests using Recom’s 700 mA LED driverand two strings of 350 mA Osram LEDs, thecurrents flowing through the two stringswere matched to an accuracy of about 87%over the entire input voltage range of theLEDsmagazine.com APRIL 2009 33Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | Next PageABE FMaGS

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | Next PageABE FMaGSdesign forum | DRIVING STRINGSdriver from 16 VDC to 36 VDC. The LEDcurrents were stable as the LEDs warmedup and no thermal runaway was observed.It is important that the two transistors areboth at the same temperature, so a copperclamp was used to thermally connect bothtransistors together to keep their V bevoltagesstable._____________________________________Over-current protectionHowever, the circuit still requires over-currentprotection. The diagram (p.33) showsthe final version of the current balancingcircuit. The addition of 1.5 Ω resistors in theemitter paths makes the circuit less sensitiveto small V bechanges and balances the currentsin the two strings to 99% accuracy.The addition of a small-signal transistoras a current monitor protects the LEDsfrom being overdriven in the case of anyLED failures. If any LEDs in string 1 (LED1 -LED5) fail open-circuit, then the current instring 2 falls to zero. However, if any LEDsin string 2 (LED6 - LED10) fail, then the currentincreases in string 1 until the voltagedeveloped across the 1.5 Ω emitter resistorreaches around 0.7 V, thus turning on theBC337 transistor and pulling the base voltageof the power transistor to ground andlimiting the current. With the componentvalues given in the circuit, the measuredcurrent limit was 445 mA with string 2 opencircuit.The circuit shown can theoretically beextended to any number of LED strings byadding an NPN transistor and emitter resistorto each additional string and tying thetransistor bases together. The current flowingthrough the reference transistor willbe faithfully mirrored by all of the othertransistors.However, considering that LEDs are highreliabilityillumination sources, and thedriver and associated components need tobe equally reliable to get the maximum lifetimeout of the system, it is recommendedthat the circuitry be kept as simple as possibleand restricted to only one or two stringsper driver.Further readingA more detailed version of this article with additionalcircuit diagrams can be viewed online:www.ledsmagazine.com/features/6/2/2.34 APRIL 2009 LEDsmagazine.comPrevious Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | Next PageABE FMaGS

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | Next PageABE FMaGSlighting | DIRECTIONALDesigning with LED directional lights:the importance of delivering lux on targetThe quality of light and the amount of light reaching the targeted area are the most important factorsin directional lighting applications, explains QUATA OCANO.LEDs are known for their potentialenergy savings and longservice life, and LED lightingis often touted for its luminous efficacyas measured in lumens per watt(lm/W). However, lm/W is not the bestperformance measure for directionallighting applications (Fig. 1) such asspot, accent and task lighting. In theseapplications, manufacturers need todesign lamps and modules that maximizethe delivered light or “usablelumens” rather than the lm/W value.Focus on usable lightThe two most important things toconsider when working with directionallight are, firstly, the amount oflight reaching the targeted area and,secondly, the quality of that light.“Unless LED products satisfy ourintensity, distribution and color renderingexpectations, we will not considerinstalling LED lamps and modules regardlessof their efficiency or cost-savings,” saysBradley Bouch, Senior Lighting Designer forWynn Design and Development. “Designershave been disappointed with LED lightsthat do not live up to their own specifications,much less the designers' expectations.LED manufacturers should simply take theirproduct and shine it on a wall next to a similarhalogen MR16.”He adds, “When the quality of light fromthe LED lamp is comparable to the halogenlamp and the product is dimmable, we willbe happy to use them. We are always lookingfor ways to improve energy efficiency, but notat the expense of the lighting quality.”In short, LED lighting manufacturersneed to design products with the emphasison the delivered light, and to provide thenecessary specifications that the designercan use to incorporate LED lights into theiroverall plans.IlluminanceThe “Holy Grails” for LED lighting over thelast 10 years have been lumens and luminousefficacy to compete with incandescent,halogen and CFL products in general lightingapplications. LEDs are inherently directionaland make excellent spot and floodlights if designed properly. However, traditionalLED light measurements are notappropriate and may be counterproductive.QUATA OCANO is senior product marketing manager with LedEngin Inc. (www.ledengin.com), asolid-state lighting company based in Silicon Valley, California.FIG. 1. Directional lighting applications.In a spot or accent fixture, the objective isto highlight a specific feature or item suchas a painting or architectural element. Theonly light that matters is the light that illuminatesthe feature.The light in the target area, or illuminance,is measured in footcandles (lm/ ft 2 ),or lux (lm/m 2 ). Rather than focus on lumensor lm/W, light sources designed for directionallighting should emphasize beam angleand lux or footcandles in the center beam toprovide suitable solutions.Quality of lightThe quality of the light in the beam isalso important to accent lighting. This ismuch more subjective than the quantityof light and encompasses light uniformity,LEDsmagazine.com APRIL 2009 35Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | Next PageABE FMaGS

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | Next PageABE FMaGSlighting | DIRECTIONALa)color rendering ofobjects or features, colorhomogeneity throughout the beam, contrastat the beam edge and glare. LED solutionshave the opportunity to surpass halogenand incandescent sources with respect to thequality of light. For instance, many halogenMR16 lamps exhibit hot spots, shadows, darkrings and fringe edge patterns. Because of thedirectional nature of LEDs, well-designedLED sources can produce a uniform beamwith a smooth gradient of light with well-controlledbeam and without the stray light thatcreates an uncomfortable glare.Lighting design specificationsLED sources need to adopt lighting industrystandards and specifications so thatdesigners can more readily specify them.When selecting accent light sources, designersconsider footcandles (lux) in the targetarea. They work with center beam footcandles(lux) and the light distribution in distancefrom the source and center beam. IESlight distribution files make it easy to designwith lamps and modules. Light color measurementsthat help a designer know how touse a light source include color temperature(CCT) with binning aligned with ANSI colorbins and color rendering index (CRI).Directional lights are traditionallyMR16 or PAR incandescent or halogenlamps defined by wattage and beam angle.Although there is a wide range of performanceeven within the halogen and incandescentmanufacturers, it is presumed thatb)FIG. 2. LedEngin’s LuxDot (a) is adirect replacement for a halogenMR16, while the LuxSpot (b) is acompact MR16 integrated module.35 W halogen from one manufacturer willperform similarly to a 35 W lamp from a secondmanufacturer. LED solutions need to becharacterized in halogen or incandescentequivalent watts with comparable color andcolor quality. For consistency, LED productsneed to follow the newly established IESNAstandards for LED testing.Types of LED directional lightingThe easiest solution to speed adoption ofLEDs is a direct replacement of the MR16halogen lamp in a standard form-factorsuch as the MR16 bi-pin (GU5.3) standard.The compact size offers a challenge for LEDsolutions accommodating sufficient thermalheat sink and the transformer. However, severalLED solutions are very close, and at leastone product, the LedEngin LuxDot , doesconform to the fit, form and function of atrue halogen MR16 (see Fig. 2).There are two predominant types of LEDsolution. The most common has multiple 1W or 3 W high-efficiency emitters packedwithin a 2-inch radius surrounded by a complexoptic to try to make a uniform beampattern. These products will meet or exceedboth the lumens and lm/W standards, butwill usually fail to deliver the needed footcandles(lux) to the targeted area in a wellcontrolledbeam.The second design approach is a singleemitter made of multiple LED chips closelypacked within a small footprint. The thermalchallenges are greater because of the densepacking but the optics are much better andthe beam much more uniform in color, lightgradient and overall efficient useof light. Figure 3 compares LEDsfrom both designs.While it is expedient todesign drop-in replacementlamps that fit into existingsockets, such solutions donot take full advantage of allLEDs have to offer. The longlifetimes of LEDs let us changethe way we think about lighting,in that the light source is not a consumablebut an integral part of design,and lighting fixtures need not be designedwith replacements in mind.The real breakthroughs will come whennew integrated modules take full advantageof LEDs, accommodate their unique issuesand provide attractive alternatives to currentlighting designs. Integrated LED lightingmodules can optimize the thermal managementand drive electronics to providemaximum efficiency and usable light. Fromlow-profile under-cabinet lighting to accentor task lighting, integrated solutions thatbreak away from the existing constraintswill ultimately provide the best solutions.Challenges of working with LEDsLike virtually every other new technology,LED lighting has challenges to overcome.The good news is that evolving complementaryproducts such as electronic controls,thermal management solutions and opticswill support the adoption of LED lightingsolutions.Low voltage AC infrastructure: LEDsrequire a direct current driver to operate,but line voltages are either 120 V AC or 220V AC. There are many low-voltage applicationstoday using halogen lamps, particularlyin spot and accent lighting. These usetransformers that are either electronic ormagnetic and typically convert line voltageto 12 V AC. LED drive electronics mustwork with a wide range of non-regulatedlow voltage AC transformers and convertthe voltage into direct current to drive theLEDs. A second issue with these transformersis that they usually require a minimumpower load that is larger than the high-efficiencyLED products consume. LED driversneed to address the potential flicker causedby some of the “dirtier” transformers. Lastly,36 APRIL 2009 LEDsmagazine.comPrevious Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | Next PageABE FMaGS

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | Next PageABE FMaGSThe biggest lighting industryforum in Asia9 – 12 June 2009China Import and Export Fair Pazhou ComplexGuangzhou, ChinaShow highlights:• Asia’s largest lighting exhibition and the 2nd largestin the world• Over 1,500 exhibitors and 48,000 expected visitors• Over 100,000 gross sqm exhibition space• Dozens of symposiums featuring global speakersFor free admission, register online now atwww.light-building.messefrankfurt.com and click onGuangzhou International Lighting ExhibitionFor information, please contact:Tel +852 2238 9964Fax +852 2598 8771LBguangzhou@hongkong.messefrankfurt.comwww.light-building.messefrankfurt.comPrevious Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | Next PageABE FMaGS

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | Next PageABE FMaGSlighting | DIRECTIONALa)b)FIG. 3. Typical beam patterns from (a) amulti-emitter vs. (b) a single emitter.LED products must maintain a power factor> 0.9 to be acceptable in commercialinstallations.Dimming capabilities: Individual LEDsare capable of dimming ranges from 100%to 0% through the traditional use of pulsewidthmodulation (PWM). However, for generallighting, it is best to work with commercially-availableoffline wall dimmers. Walldimmers adjust power to the lighting systemand have been designed for halogenloads >20 W. LED MR16 solutions typicallyrun in the 6–7 W range. This can lead to limiteddimming capabilities, flickering at lowdimming levels and non-start of the transformer.Wall dimmers have a turn-on thresholdaround 3 W, so a 20 W halogen lamp canbe dimmed down to about 15%. With LEDlamps, this threshold translates dimmingto 30–40%. This is true for single LED lampson a dimmer, but multiple lamps on a singletransformer/dimmer will reach lower dimminglevels as the load increases.Thermal considerations: LED productsare more efficient than their incandescentcounterparts and require a unique approachto thermal management. Rather than theradiated heat from the infrared energy thatincandescent sources emit, most of the LEDheat is generated from the LED die and mustbe conducted away. LED packaging technologyis becoming a key part of the overallthermal solution. Designs that managethe heat most efficiently can extend the limitsof the system and increase the light outputwithout sacrificing long-term reliability.Depending on the size or power of thelamp, there will either be passive or activecooling. Passive cooling is simply a relativelylarge metal heat sink, usually withfins to increase the metal surface area forbetter heat dissipation. Active cooling solutionscan be fans or a diaphragm. Passivelycooled solutions are quiet but somewhatbulky, while active cooling systems allowfor a more compact stylish light module.The future is bright with LEDs.Optical efficiency is the challenge.Fusion Optix is the solution.Fusion Optix optical components are designed for maximumlight control with minimal light loss, resulting in highly effi cientLED lighting systems appropriate for architectural lighting andgeneral illumination.• Diffusion Lenses offer versatility and control, whilemaintaining high optical effi ciencies• Light Guides enable ultra-slim form factors and uniform lightdistribution• LED Assemblies are precisely binned and thermally managedto provide color uniformity and long lifetime• Fusion Optix offers rapid cost effective prototyping andcustomization services for OEMs in order to bring innovativeproducts to market quicklyFusion Optix, Inc. • 19 Wheeling Avenue • Woburn, MA 01801 • +1 866.506.8300 • www.fusionoptix.com38 APRIL 2009 LEDsmagazine.comPrevious Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | Next PageABE FMaGS

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | Next PageABE FMaGSlighting | DIRECTIONALBoth require some installation considerationfor proper airflow around the fixtureto dissipate the heat.LED advantages incorporated in productsSimilar design considerations apply to manyLED-based directional lighting solutions.As examples, we will look at two productsdesigned and manufactured by LedEngin,namely MR16 halogen lamp replacements(the LuxDot brand) and integrated MR16fixtures (LuxSpot brand) — see Fig. 2.High flux density: Inside the LedEnginmodules, a single, multi-chip emitter iscoupled with a secondary lens that controlsand shapes the emitted light into a high-lux,high-quality beam for the most efficient useof lumens. This results in a well-controlledlight gradient, a smooth transition at thebeam edge and uniform color over the beamangle. This provides better light quality thanmost halogen lamps that have hot spots,dark rings and fringe patterns around theedge and is preferable to LED solutions thatmust align multiple beams into a single radiationpattern.High quality color rendering: Takingadvantage of high performance LED chipsand unique phosphor recipes, LedEnginproducts have CRI values >80 across allcolor temperatures, with a CRI of 90 availablein warm white. Designers will not considerlamps with CRIs less than 80, and 90is better. However, CRI does not provide acomplete gauge of true color rendering; thequality of light in the warmer red and fleshtoneregions is also important.Thermal management: Proprietarypackaging produces a very low thermalresistance emitter, and in turn this allowsthe LED to be driven harder to provide agreater amount of directed light in thebeam without sacrificing the long servicelife and while still maintaining a smallform factor. Compact packaging allowsLedEngin modules and lamps to conformto existing MR16 fixtures and PARfixtures.Momentum builds for LED lightingLedEngin has coined the phrase “Lux onTarget” to reinforce the importance of deliveringtrue quality light when implementingdirectional lighting solutions. "We achieveLux on Target by integrating a small, powerfulLED with optimized optics, heatsinksand driver for an overall reliable, compactsystem," said Uwe Thomas, director of technicalmarketing.Improvements in LED lighting performanceand the development of complementarytechnologies make solid-state lightingan increasingly attractive option, particularlyfor the many directional lighting applicationsthat play so well to LED strengths.Add the steadily increasing demand forsustainable design, and LEDs will becomethe first choice for more and more lightingapplications.CUSTOMLED SOLUTIONS.FOR ACCELERATINGYOUR BRILLIANTDESIGNS.When it comes to accelerating your brilliantlighting designs for medical, dental, safety andsecurity, industrial and architectural markets,rely on PerkinElmer for complete customLED solutions including:n optical design and testingn mechanical and electrical designn thermal managementn custom chip-on-board packagingAccelerate your competitive edge withPerkinElmer LED Illumination Solutions.www.perkinelmer.com/ledsolutionsLEDsmagazine.com APRIL 2009 39Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | Next PageABE FMaGS

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | Next PageABE FMaGSNEARLY 5,000 OF THE WORLD’S MOST INFLUENTIAL AND MOTIVATEDMANUFACTURERS, EQUIPMENT SUPPLIERS AND END-USERS COME FACE-TO-FACEto evaluate products and services and get the information they need to conduct business.February 10–12, 2010Santa Clara Convention CenterSanta Clara, CAwww.strategiesinlight.comMORE THAN 2,000 REGISTRANTS IN 2009!For 11 years, Strategies Unlimited and PennWell Corporation have produced abusiness-oriented conference on high-brightness LEDs known as Strategies in Light.Held every February in Silicon Valley, this conference is considered to be the world’spremier event on this subject. This event provides an annual forum for presentingcurrent commercial developments in high-brightness LED applications and providingunparalleled networking opportunities for component and equipment suppliers, manufacturers,and end-users of HB LED devices.The conference and associated exhibition continues to attract record attendance –this year’s event was the biggest to date with more than 2,000 registrants. Strategiesin Light is the longest-running and largest event in the LED industry – no other event canmatch our commitment to growth and furthering the interests of the industry.FOR MORE INFORMATION ONEXHIBITING OR SPONSORINGSTRATEGIES IN LIGHT IN THE U.S:WEST COAST SALES:Tim Carli, (650) 941-3438, ext 23.tcarli@strategies-u.comEAST COAST SALES:Jeff Gallagher, (603) 891-9147jeffg@pennwell.comSeptember 16–17, 2009Exhibition: Pacifico Yokohama Hall AConference: Pan Pacific Yokohama BayHotel Tokyu Yokohama, Japanwww.strategiesinlight.com/ledjapan2009MORE THAN 2,700 REGISTRANTS IN 2008!The inaugural event in 2008 attracted more than 2,700 registrants – including morethan 60 exhibiting companies. Japan plays a leading role in both the production anduse of high-brightness LEDs and accounts for approximately 47% of the worldwideHB LED supply. Home to the world’s largest HB LED manufacturer, as well as five ofthe world’s top 10 HB LED suppliers, Japan also accounts for about $1 billion in HBLED consumption.Whether you are supplier, LED manufacturer trying to reach customers, anattendee looking for new product information, or a buyer exploring the latesttechnologies, Strategies in Light events can help you achieve your goals!CO-OWNED AND CO- PRODUCED BY:FOR MORE INFORMATION ONEXHIBITING OR SPONSORINGSTRATEGIES IN LIGHT IN THE U.S:USA, EUROPE, AND ASIA (OUTSIDE JAPAN)WEST COAST SALES:Tim Carli, (650) 941-3438, ext 23.tcarli@strategies-u.comEAST COAST SALES:Jeff Gallagher, (603) 891-9147jeffg@pennwell.comJAPAN:Manami Konishi, +81 (3) 5645-1273manami.konishi@ex-press.jpCOMMERCECONTENTCOMMUNITYLeading source of marketinformation for photonicscomponents and HB LEDsThe leading information resource for the global LED community,serving thousands of readers that specify, design and manufactureLED-based products for a wide range of end-use applications.Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | Next PageABE FMaGS

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | Next PageABE FMaGSlighting | HEAT REMOVALTaking the heat out of LED fixturesHeat sinks, heat pipes and synthetic jets are among the technologies being used byLED fi xture makers to remove heat from their products and enable them tooperate correctly, reports FRANÇOISE VON TRAPP.Temperature has a direct impact on theoptical and electrical performance ofLEDs, as well as the overall qualityand reliability of LED-based products. In atypical LED-based lighting fixture, thermalenergy is generated within the LED chip, travelsthrough the LED package, over the interconnectpath and into a metal-core PCB,where it must have some means of escape.From a thermal management perspective, thebiggest challenge in designing LED-based fixturesis maintaining the LEDs at a specifiedoperating temperature. LED chips are highlytemperature-sensitive; as the temperatureincreases, the lifetime of the LED is reduced,and at higher temperatures the overall lightemitted from the LED is reduced.Additionally, LED lighting fixtures oftencontain multiple LEDs, which can result invery high levels of dissipated power. Standardlight fixtures with well-defined formfactorstend to be restricted by size, whichreduces the cooling capacity and necessitatesinnovative cooling solutions.FRANÇOISE VON TRAPP is a contributing editor of LEDs Magazine.Designing for LEDsEffective cooling of LED fixtures beginswith a good design that generally includessome form of heatsink to remove the thermalenergy from the fixture body. In manyfixtures, the heatsink is an integral part ofthe housing design.For electronic devices in general, a passiveheatsink that relies on cooling by airflow over a large-surface-area structure isoften assisted by active cooling using fansor liquid cooling via a coldplate with liquidloops. However, LED system designers tendto shy away from traditional active devices,due to a number of concerns such as acoustic,reliability, form factor,and cosmetic considerations.“Telecomhas learned to adjust tothe inadequacies of fans,”said Mick Wilcox, director ofmarketing for Nuventix, a thermalmanagement company basedin Austin, Texas. He explained thatthey’ve learned to compensate bybuilding in redundancies and canswap out fans when they fail. This is not agood solution for LED lighting, which needsdevices that have a similar lifetime to theemitters.Liquid cooling has not been readilyadopted by LED fixture makers either,because a leak in the pipe can wreak havocon the fixture. Luckily, as the LED industrymatures, solutions more suited to its particularconcerns are being addressed. Twoemerging technologies available to enhancetraditional LED cooling designs include syntheticjet coolers and copper heat pipes thatuse phase-change processes in lieu of liquidto move heat away from the source.Heatsinks: the thermal workhorseSince the LED industry – especially the highbrightnesssector – is relatively young, thereare a multitude of possibilities for both newand old companies that manufacture heatsinks,notes Lars-Erik Lindström, marketdevelopment manager with Sapa ThermalManagement, a Swedish manufacturer ofextruded aluminum heatsinks.What makes a good heatsink? Factorsto take into consideration are their shape,design, and material properties. Die-castaluminum provides benefits including formFIG. 1. Flared-pin fi n heatsink.Cool Innovationsfactor and “almost limitless” shaping possibilities,but is poor at conducting heat. “Normaldie casting alloys have a heat dispersing coefficientof about 120 W/mK,” said Lindström.“If you use extruded aluminum instead, thesame coefficient can be as high as 210 W/mK.”Also, the height-to-width ratio, and thereforethe efficiency, of die-cast heatsinks is limitedby the release angle needed to get the finishedpart out of the die.The extruded aluminum heatsinks developedby Sapa have a high fin ratio, and areadaptable to the particular design of the LEDfixture. Lindström notes that for industrialuse, the surface finish of a product is probablynot the highest priority, compared withfunctionality and cost efficiency. “However,for home use and architectural solutions, wecan add high surface finish and design possibilitiesto the equation,” he said.A line of heatsinks featuring a flared pindesign has been introduced by Cool Innovations,an Ontario-based heatsink manufacturer(Fig. 1). According to CTO BarryDagan, these flared-pin fin heatsinks aresuitable for LED assemblies because they'redesigned to provide optimal performanceLEDsmagazine.com APRIL 2009 41Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | Next PageABE FMaGS

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | Next PageABE FMaGSlighting | HEAT REMOVALin the natural convection mode.The flared structure has a largetotal surface area combined witha wide spacing between pins thatallows air to circulate in a significantlymore efficient manner thanin a heatsink with vertical pins. Thestaggered pin design and the omnidirectionalstructure, which allowsair to enter and exit the pin arrayfrom any direction, both contributeAdvanced Thermal Solutionsto the efficiency.Dagan claims that flared pin findesigns often can be used in situationsthat would otherwise requirea much larger conventional heatsink,or an additional cooling device such asa fan. He said that flared pin fins are a greatfit for extreme, high-temperature outdoorenvironments, for very hot LED applications,and for large LED assemblies. “Although theLED market wasn’t an initial target for thesedevices,” said Dagan, “the calls started pouringin” when the products were unveiled (seewww.ledsmagazine.com/press/17958).Advanced Thermal Solutions, based inNorton, MA, offers several heatsink optionsfor use in LED fixtures of different types. Forexample, the company’s linear heatsinks areavailable specifically for LED strips, whichare widely used in architectural lighting. Itspatented spread-fin array reportedly maximizessurface area for more effective convectioncooling, particularly when air flowis limited, such as inside display cases. Thecompany also offers round heatsinks specificallyfor round LED boards, which are usedto replace halogen lamps in applicationssuch as spotlights and down lighting. Theround heatsink (see Fig. 2) has a special starshapedprofile fin design that maximizessurface area for effective convection andradiative cooling in the vertical mountingorientation, for example, inside ceilings.Heat pipesWhen heat is concentrated in an area whereadequate airflow is limited, heat pipes can beused to move the heat to where it can be efficientlyremoved by either a stand-alone heatsink,or a heatsink with a fan. Additionally,as heat pipes can be formed into differentshapes, they can be incorporated intothe heatsink design, allowing for a smallerFIG. 2. An LED-based spotlight with a round, fi nned heatsink. An IRview is shown at right.Noren ProductsHeat inEvaporator sectionLiquidVaporAdiabatic sectionWickheatsink to be used.According to Dennis Scott of Noren Products,a heat pipe manufacturer based inMenlo Park, California, copper heat pipesare isothermal structures that utilize a phasechangeprocess to create a passive heat pumpthat moves heat from the source (e.g. an LEDboard) to the output (e.g. a heatsink). Insidethe copper tube is a wick structure, along withenough fluid to “wet the wick”. When heat isintroduced to the copper tube, the water inthe wick vaporizes and pushes the heat downthe length of the tube to the outlet. As it cools,vapor condenses and re-wets the wick, creatinga closed loop system (Fig. 3).Scott points out that the heat pipe by itselfis not a cooling device, but requires a heatsource at the input, and method of removalat the outlet. The way in which the pipe isattached to the heat source and to the outletis important, and Noren works only withcustom designs. “As simple as the concept is,it provides a pretty complex solution,” saidScott. “Once it’s in place, it’s a passive solution.But putting it in placeisn’t as easy as most peoplethink.”Scott said heat pipe technologyis fairly new to theLED industry, and is provingto be especially suited tohigh power LEDs in applicationssuch as street lighting,where a longer lifetime ofcooling is required – such as10 or more years. Heat pipescan distribute heat over anLED street light’s housingfor 10-15 years. Another LEDapplication suited to heatpipes is track lighting. “Instead of individualheatsinks for each light, heat pipes canbe used to move the heat to a single, efficientheatsink,” explained Scott.Synthetic jetsSynthetic jets are an alternative option tofans as a method of active cooling. This proprietarytechnology, developed by Nuventix,comprises a module that creates turbulent,pulsated air-jets that can be directed preciselyto locations where thermal managementis needed. According to Mick Wilcox,reliability is the biggest advantage syntheticjets have over fans, because their lifetime istwice that of the LEDs themselves.Here’s how it works. Wilcox compared itto the simple act of breathing, with inflowand outflow through the same opening, andpulses of air being created by a diaphragm.In the case of a SynJet (Fig. 4), the chamberis powered electromagnetically, oscillatinga diaphragm made of elastomer upand down at 50 HzHeat outCondenser sectionFIG. 3. Heat pipes use a phase-change process to transfer heatfrom the source to the output device. See www.ledsmagazine.com/news/6/2/10 ________ for an example of a street lighting fi xture in which aheat pipe transfers thermal energy from the optical module to theheat sink.to propel rapid-firepulses of turbulentair out of the chamberand through theheatsink. The pulsesmaintain a higherheat coefficient, andtherefore can coolthe same amount ofair with half the airflowof a fan.Acoustically, the50 Hz frequencyis below human42 APRIL 2009 LEDsmagazine.comPrevious Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | Next PageABE FMaGS

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | Next PageABE FMaGSlighting | HEAT REMOVALFIG. 4. Nuventix has supplied SynJetcooling modules to a number ofluminaire manufacturers. A blackSynJet and heat sink (left) areattached to a Fortimo light enginefrom Philips. Synthetic jets (right)are created by rapid-fi re pulsesof turbulent air produced by anoscillating diaphragm.Nuventixhearing levels, while fans run at a higherRPM right in prime hearing frequency,explained Wilcox. The form-factor advantageis that it cuts the size of the heatsinkby 2 or 3×, including the SynJet module.Wilcox said this allows system integratorsto design much more compact lighting fixtures,and allows them to shrink or moldthe heatsink to suit the aesthetic appealof the fixture.Synergies exist between different technologies,and several can be included in thedesign of one LED cooling solution. Accordingto Wilcox, one scenario might involveattaching the heat source to a heat sink withan integrated heatpipe and then attachingthe synthetic jet module to the heatsink. Headded this solution would be proposed in a“very thermally challenging situation” due toits cost. The heat pipe would be eliminated,if possible, to keep the cost down.ConclusionAs the LED market matures, so do the solutionsto thermal management limitations.Advancements in heatsink technologies,copper heat pipes and synthetic jet modulesare paving the way for aesthetically pleasing,efficient, acoustically tolerable, reliable LEDfixtures that light our way._________Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | Next PageABE FMaGS

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | Next PageABE FMaGSKEEPINGLEDsCOOLIS HOT STUFF.Bergquist’s Cool Little Secret To Extending Power LED Life.Thermal Clad ® – The designers solutionfor Power LED applications.Thermal Clad is a metal-based circuit board for use with surface mountcomponents that efficiently transfers heat from the circuit layer to themetal base. No other circuit board does a better job of removing heatfrom electronic components. Because Thermal Cladis a metal-based material, it can be configuredfor special shapes, bends, and thicknesses.This distinctivecomposition allows for Power LED lampplacement into virtually any application.Superior technology helps extendLED life and reliability.Power LED light output and long life are directlyattributable to how well the LED’s are managedthermally. Mounting your Power LED’s on ThermalThermal Clad keeps even the smallest LEDscool - like this one by Innovations In Optics.Clad assures the lowest possible operating temperatures and brightestlight output.Thermal Clad is available as panels, or individual circuits tomeet your specifications.A world leader in thermal management solutions.Heat is the enemy of LED’s and other silicon containing electroniccomponents. Bergquist is the world leader in thermal managementmaterials supplying some of the best names in the business suchas Gap Pad ® , Sil-Pad ® , Hi-Flow ® , and others.HOT applications for LED’s mounted on Thermal Clad:• Headlamp / Daylight Running Lamp• Instrumentation• Interior / Exterior / Accent• Turn / Stop SignalsContact us today for your FREELED test circuit board.Now you can test multiple packagesof LEDs on Thermal Clad. Qualifyfor your FREE circuit board online:www.bergquistcompany.com/coolfutureor call 1-888-942-855218930 West 78th Street Chanhassen, MN 55317 • (952) 835-2322 Fax (952) 835-0430 • www.bergquistcompany.comThermal Products • Membrane Switches • Touch Screens • Electronic ComponentsPrevious Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | Next PageABE FMaGS

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | Next PageABE FMaGSthermal | SYSTEM DESIGNManaging heat in power LED systemsfor optimal performanceWhen designing a solid-state solution with power LEDs, one cannot underestimate theimportance of the thermal system design, as encapsulated in the phrase “Think Thermal First”.RUDI HECHFELLNER explains.To understand the role of thermaldesign in LEDs, it’s important toreview how system and electronicdrive conditions influence light output performanceand long term behavior of highpowerLEDs. The parameters shown in Fig.1 are all influenced by the junction temperatureof the LEDs, demonstrating the importanceof this subject.Temperature has a direct impact on opticaland electrical performance as well as onthe overall quality and reliability of an LEDbasedproduct. Therefore, it is critical thatengineering teams understand the system’sthermal parameters, and focus on thermodynamiccompetencies.These parameters are all interconnected.For example, a higher drive current shouldincrease the light output of the LED. However,the higher current increases the dissipatedpower, causing heating within theLED, which has a negative impact on lightoutput. Also, conversely, a higher junctiontemperature (caused for example by a higherambient temperature) causes a reduction inthe LED’s forward voltage, reducing the dissipatedpower for a constant-current source.The parameter dV/dT (the change in forwardvoltage as a function of temperature)is not constant from LED to LED, unlike ina standard silicon CMOS diode. For this reason,we do not suggest using multiple highpowerLEDs in parallel, even when forwardvoltagebins are selected very carefully atroom temperature. When the system reachesits operating temperature, the different dV/dTvalues can cause significant currentmismatch between parallel paths,resulting in different light outputsfrom LED to LED.SSL thermal systemsA typical thermal system is shownschematically in Fig. 2. The thermalenergy generated in the LEDjunction ‘travels’ through the LEDpackage, over the interconnectthermal path and into the PCB. ThePCB conducts the heat through thethermal interface material (TIM)and into the heat sink, which increases thesurface area for ambient air exposure.When evaluating the system for possibleperformance improvement, we find thatmultiple factors contribute to the system’stotal thermal path. To reduce thermal resistance,there are several routes that may beused individually or in combination:1. Optimize the entire system for thermalperformance: For example, when designingthe physical system of a luminaire,shorten the thermal paths to the best ofyour ability, while still meeting the designspecification.2. Optimize each thermal path componentto improve performance: For example, usecopper vs. aluminum.3. Remove components to eliminate theirresistances: For example, eliminate thermalinterfaces by mounting the LEDdirectly onto the heat sink.Selecting from these options, the designRUDI HECHFELLNER is technical marketing manager with Philips Lumileds Lighting Company(www.philipslumileds.com), San Jose, California, USA.Short-termbehaviorBehavior asjunction temperatureincreasesLong-termbehavior operating time FIG. 1. A number of LED operating parametersare affected by an increase in the LED junctiontemperature.engineer will need to weigh the trade-offsbetween performance, cost and industrialdesign to achieve the desired results for thespecific application.To optimize the entire system for thermalperformance, a good understanding of theactual operating environment is a requirement.Factors that need to be consideredinclude airflow, as well as regulatory parameterssuch as UL or CE certifications thatlimit the maximum temperature of the system.Without even touching on the choice ofLED, three factors come to mind as vital tothe optimization of a circuit for thermal performance.As discussed below, these factorsare heat sinks, choice of PCB, and testing.Heat sinksHeat sinks or heat spreaders are the part ofthe thermal system that distributes the heatenergy to the ambient air. Active airflow dramaticallyincreases the effectiveness, but inmost SSL applications this is not an optionbecause of lifetime, form factor and noiselimitations. Therefore, surface area is of theLEDsmagazine.com APRIL 2009 45Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | Next PageABE FMaGS

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | Next PageABE FMaGSthermal | SYSTEM DESIGNLED chipHeatsinkInterconnectLED to substrateSubstrate or PCBessence and often the limitation of the entirethermal system. Even though a heat sinkseems to be the most straightforward component,it also has the highest potential foroptimization. Engineers are on the look outfor new and advanced materials and methodsto differentiate their heat sink design.For example, the introduction of thermally-conductiveplastics opens a newdimension of lighting solutions. Thermalsystems can now be integrated into theenclosure of products manufactured inhigh volumes by injection molding withthe added benefit of less weight. Accordingto Jeff Panek, GM of Cool Shield Inc., “MostThermalinterfacematerialFIG. 2. Schematic showing main elements of an LEDthermal system.of today’s SSL applications areconvection-limited rather thanconduction-limited. Therefore atless than 300 linear foot/minute(1.52 m/s) of air, a 20 W/mK thermalplastic heat sink can workas well as a 180 W/mK aluminumheat sink. This is becausethe system is not constrained byhow quickly the heat can move through thethermal system, but rather constrained byhow effectively it can convect the heat of thesurface into the ambient air.”The most efficient way to improve theresistance in the thermal path is to eliminatecertain thermal interfaces. This can beachieved, for example, by completely removingthe PCB and soldering the LED directlyonto the heat sink. Of course, this creates theproblem of connecting the LED to the powersupply in the absence of a PCB. One solutionis a molded interconnect device (MID) thatenables higher currents and higher light outputwith increased drive current while keepingthe junction temperature the same. Insuch a case the use of advanced materialsand methods can become the main enablerin meeting a specification like Energy Star®or reducing the component count for a morecost-effective solution.Thermal materialsThe thermal characteristics of power-LEDbasedsystems have caused engineers toadopt the metal-clad PCB (MCPCB) as a primarymaterial instead of FR4 boards. TheMCPCB “Star” board is a commonly-usedformat, but it raises system cost, resultingin ongoing work to reduce it withoutsacrificing performance. As shown in thetable on p.48, using MCPCB as the indexreference for star board designs, there arenow several alternatives that offer similaror even improved thermal performance atlower cost ratios.Thermal interface materials (TIMs) areused to connect a solid-state lighting assemblyto an external heat sink. Depending on_______________Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | Next PageABE FMaGS

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | Next PageABE FMaGSwebcastsMay 2009 Sponsorship OpportunityChallenges and Opportunities for the LED Lighting Fixture MarketSPEAKER: Vrinda Bhandarkar, Senior Market Research AnalystStrategies Unlimited, World’s Leader in Photonics Market ResearchIn recent years, LED technology has made impressive performance gains, which in turn have improved the efficacyof LED lighting fixtures. The adoption of LED lighting fixtures in the general lighting market will require a new wayof looking at lighting, and the value of lighting. The webcast will discuss the drivers and challenges that affect theemerging LED lighting fixture industry.SPONSORED BY:Future WEBCAST Topics in the LEDs and LightingSeries include:• HB LED Market Overview• Thermal Management (Part 2)• Green Lighting Model with LEDs• LED Drivers*Find out about the benefits of sponsoring the upcoming webcasts.• Understanding White LED Performance• Advantages and Drawbacks of LED Technology• Interior Illumination Using White LEDs• LED Design ChallengesArchived EventsLED Luminaire Photometry & Performance TestingSPEAKERS: Todd Straka, Director, Lighting Services , IntertekChristopher Durell, Vice President Sales & Applications Engineering, SphereOptics, LLCThis Webcast discusses performance standards developed for testing solid-state lighting products, includingLM-79 and LM-80. The speakers describe the testing requirements of these standards and other performancetesting options, explaining the types of measurement that are required and the relevant test methods. TheWebcast also looks in detail at the test equipment options that companies should consider, identifying the keypieces of equipment that are necessary to make the measurements for each standard. The Webcast also discussesenvironmental performance testing.More Archived EventsThermal Design for Enhanced LED PerformanceThis Webcast explores the fundamentals of thermal management, focusing on simulation and the correct choiceof materials.Market Trends and Emerging Applications in the LED IndustryThis presentation covers major trends in the HB-LED market, and reviews developments in the major applicationareas, focusing in particular on the LED lighting sector.Essentials for Designing LED LuminairesThis Webcast discusses the key design factors that need to be considered when building LED-based luminaires.VIEW ALL CURRENT, FUTURE AND ARCHIVED EVENTS AT:www.ledsmagazine.com/webcastsPrevious Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | Next PageABE FMaGS

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | Next PageABE FMaGSthermal | SYSTEM DESIGNthe application, differenttypes of TIMs are availableon the market. In general,this layer should be verythin but able to increase theconducting surface areas byeliminating air gaps thatwould otherwise add to thethermal resistance.Material performance and cost comparison of PCB alternativesPCB materialVirtual testingTesting for thermal performanceis an expensive and time-consumingprocess that requires prototypes to bebuilt and that uses various measurementtechnologies such as infrared cameras.Evaluation programs specifically developedfor solid-state lighting, such as QLED®from Future Lighting Solutions, provideengineers with thermal simulation tools,which can deliver results based on customconditions within minutes. Changes canbe implemented and analyzed to executeAverage thermalresistance (K/W)*Relative cost per “Star”boardMetal-core (MC) PCB 20 100%High performance MCPCB 15 150-200%FR4 open vias 17 18-60%FR4 fi lled and capped vias 13 25-85%Ceramic (AlN) 11 200-300%Ceramic (Al 2O 3) 16 60-70%* Junction to bottom of boarddifferent case studies. Such an approach isalso very useful in applications with pulsedoperating conditions, for example, automotiveturn indicators or cell phone camerafl a s h e s .SummaryThe solid-state lighting industry recognizesthe importance of thermal systems, but thecomplexity of these systems is often underestimated,and the impact on the performance ofpower LEDs is not well documented.However, the mantra“Think thermal first” isbecoming more embeddedin the SSL engineering community.Pushing productperformance and lifetimeby optimizing the drive currentand emitter count isresulting in new materialsand implementation methods.Companies that historicallyfocused on electro-mechanics (i.e. connectorcompanies) now seem to be shifting tothermo-electric systems to meet the SSL industry’sneeds. Materials and methods primarilyused in very advanced, high-volume productsare now becoming available to the SSL engineerand designer. In the end, “Think thermalfirst” may not be just an engineering motto, itpossibly could be a key differentiator that willtrigger development of a successful product inthe emerging SSL industry.______________48 APRIL 2009 LEDsmagazine.comPrevious Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | Next PageABE FMaGS

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | Next PageABE FMaGScontinued from page 52last wordmove very rapidly. Although this is a positivetrend, it can also create issues. For example,customers may want to wait for the next technologystep before committing themselvesto an LED-based solution. There is tensionbetween the fast pace of technology change,and customer and product requirements.We should be able to provide intelligentupgradeability for customers, to allow theeasy incorporation of new technology. Oneexample is a board layout that can incorporatedifferent Dragon LEDs that operate atdifferent power levels from 1 to 5 W.For cool white LEDs, customers are startingto become satisfied with the efficacy(lm/W value), but for warm white, the performanceis borderline for many applications,and definitely needs improvement. Butin addition to lm/W, there are many aspectsof LED performance that need further work— for example binning, lifetime and reliability.Simultaneously, there is further work todo throughout the whole value chain — forexample in drivers, or thermal management— so that people can realize the full value ofthe LEDs’ high efficacy.We continue to work on many aspects oftechnology, for example new chip technologywith much better linearity of efficiencyversus current density. We can’t share all thedetails of our R&D program, but we certainlyhave enough LED development work to keepus very busy for at least the next five years.OLED lightingOLED lighting is still in the R&D phase,and we are now trying to validate the manypotential applications. Even the simple conceptof a glass plate that emits light createslots of opportunities, and we are workingwith designers to explore these possibilities.For example, we are trying to determineways to use attributes such as a window-likepanel that is transparent when switched off,but can emit light at night.In parallel, we are working on technologyissues, and achieved 62 lm/W last year for awhite emitter. We have to develop low-costencapsulation schemes, for example, andimprove and optimize the substrate andthe emitter stack. The highest priority is toreduce the manufacturing cost of the panels,but we also need to improve features such asefficiency, lifetime and color stability. Andthis work needs to be done in tandem witha consideration for customer-required features.For example, a bottom-emitting structuremight be the easiest to implement inproduction, but does not necessarily offerall the features that customers want.With funding from German and EU bodies,we are progressing along our projecttimeline and passing through variousgates that will eventually move OLED lightingproducts into full production. There is ahealthy community making good progressin this area, with a number of competitorsracing to become leaders in the field.MORE DETAILS: www.osram-os.com_____________________________LEDsmagazine.com APRIL 2009 49Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | Next PageABE FMaGS

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | Next PageABE FMaGSPRODUCT focusTO PROMOTE YOUR PRODUCT HERE, PLEASE CONTACT JOANNA HOOK AT joannah@pennwell.comOR MARY DONNELLY (U.S. SALES) AT maryd@pennwell.comCARCLO TECHNICAL PLASTICSCarclo announces new optics tosupport Avago and Luminus DevicesCarclo Technical Plastics, a global leader in LED optics, announcesthe immediate availability of 26.5mm optics and holders for theAvago Moonstone and Jade LEDs, as well as the Luminus DevicesSST-90 and SSR-90 light engines. Specifically designed andoptimized for these light sources, Carclo’s new optics are availablein plain tight and elliptical versions, as well as Carclo-exclusivefrosted narrow, medium, and wide beam angles.Tel: +1 724 539 6982+44 (0) 774 0205 338Email: jim.oconnor@carclo-usa.comian.bryant@carclo-plc.comWeb: www.carclo-optics.comD-LED ILLUMINATION TECHNOLOGIESD-LED’s MegaACE-ER-SD is a Professional LED engineengineered for use in The Entertainment, Media, and Architecturalmarkets.Enables Flicker free light with full control over dimming at any powerlevel, controls up to 432 LEDs (350mA) or 216 LEDs (700mA).Stand alone or DMX512 controlled, and features other operatingmodes as well. “CE”, “FCC”, “cTUVus” approved, and drives all“high brightness”, “current regulated” LED’s on the market today.Tel: +972-9-7444-222Fax: +972-9-7466-466Email: info@d-led.netFRAEN OMGOptics for LED street lightingFraen Corporation’s Optical Design and Manufacturing Group(Fraen OMG), the World’s leader in providing standard andcustom-developed optical solutions for high-power LEDs, hassuccessfully designed several innovative optical solutions tosatisfy the outdoor area lighting and street lighting markets.These patent pending solutions have been designed to meet themost challenging lighting requirements suchas IES Types I thru V.KHATOD OPTOELECTRONIC S.R.L.The future is now: ZetalensThe ever-evolving Power LED technology has led Khatod to realizeproducts that perfectly meet the new LED mechanical dimensions.Khatod showcases ZETALENS, the new futuristic lens whichhouses 7 LEDs and is fit for those applications where high lightintensity as well as diffuse light without shadows are required.Visit our website for details on Zetalensand all of our other product lines.Tel: 1-781-205-5300Email: streetlightoptics@fraen.comWeb: www.fraenomg.comTel: +39 02 66013695Fax: +39 02 66013500Email: khatod@khatod.comWeb: www.khatod.comKINGSUN OPTOELECTRONIC CO., LTD.Remote Wireless Control SystemKingsun has developed the Remote Wireless Control Systemwith its own patent which could realize remote management toLED street lights and tunnel lights. This system not only couldcontrol on-off switches and dim the light remotely ,but alsocollect relative operating data, which enables the LED streetlight management more convenient and easier.LEDENGIN, INC.LuxDot – LED MR16 replacementlamp delivers “Lux on Target”LuxDot delivers the equivalent of a 35W narrow flood halogenlamp in a standard MR16 profile. Plug-n-play replacementsimplicity and quality illumination without hot spots or darkrings. Pay back in less than 9 months!Tel: +86-769-83395678Fax: +86-769-83395679Email: ks_sales15@kingsun-china.comWeb: www.kingsun-china.comTel: 408-492-0620Fax: 408-492-0640Email: sales@ledengin.comWeb: www.luxdot.net50 APRIL 2009 LEDsmagazine.comPrevious Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | Next PageABE FMaGS

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | Next PageABE FMaGSPRODUCT focusTO PROMOTE YOUR PRODUCT HERE, PLEASE CONTACT JOANNA HOOK AT joannah@pennwell.comOR MARY DONNELLY (U.S. SALES) AT maryd@pennwell.comLEDENGIN, INC.LuxSpot now available in12VAC optionSleek, compact LuxSpot LED lighting module now offered ina 12VAC option as well as the original 24VDC. LuxSpotdelivers the performance equivalent of a 50W narrow floodhalogen lamp without the usual hot spots or dark rings.LUTRONLutron introduces highperformance dimming driverThe Hi-lume ® LED driver is an intelligent and controllabledriver that dims LEDs from 100% to 1% of total light output.It is a constant current driver for 25 Watts, is compatible withLutron EcoSystem ® and 3-wire controls, and has universalvoltage (120V and 277V). For more information, or to become aqualified fixture manufacturer,please contact:Tel: 408-492-0620Fax: 408-492-0640Email: sales@ledengin.comWeb: www.luxspot.netTel: (610) 282-6341Email: HiLumeLED@lutron.comWeb: www.lutron.com/HilumeLEDOCEAN OPTICSSimple handheld measuring is hereSay hello to Jaz: the handheld optical-sensing instrument that’sperfect for radiometric analysis of LEDs, flat panel displays,lamps and other radiant sources. Use Jaz to determine intensity,color temperature and more – without a PC!TERRALUX, INC.TerraLUX LED Light Engines ®for retrofits and replacementsLeadership in OEM SSL lighting design and manufacturingfor general and architectural lighting, industrial, medicaland consumer markets.Tel: +1 727-733-2447Email: info@oceanoptics.comWeb: www.oceanoptics.comTel: 866-498-1564Fax: 866-919-2515Email: CKalin@TerraLUXcorp.comWeb: www.TerraLUXCorp.comUPEC ELECTRONICS CORP.Unique and Innovative product —Fish LampUPEC’ s Fish Lamp can be used to collect lighting to attractspecific marine biology with specific spectrum of light. Low Power Consumption (72W vs. 1500W) DuPont TOM substrate has excellent durability & stability Longer lifetime than Metal Halide, at least 5 years Environmentally friendly High Brightness LED fish lamp(36000 lux @1m)Email: ledsmg@u-pec.comWeb: www.u-pec.comVOSSLOH-SCHWABESCHWABEDigiLED Mono CA new brightnesscontrol moduleThe cost-effective and easy to use dimming control moduleDigiLED Mono CA from VS is the best-in-class device of itstype to control monochromatic & white LED modules. Theoutput of 5A enables the dimming of a complete 10m roll of themonochromatic LEDLine Flex SMD modules with only oneDigiLED Mono CA. Its compact design allows the integrationinto luminaires.For more informationplease visitwww.vs-optoelectronic.comLEDsmagazine.com APRIL 2009 51Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | Next PageABE FMaGS

Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | Next PageABE FMaGSlast wordLighting market presents numerousopportunities for LED manufacturersThe prospects are good for strong growth in certain lighting sectors, saysBERNHARD STAPP, vice president, solid state lighting, OSRAM OPTO SEMICONDUCTORS.Within the general illuminationmarket for LED lighting, OsramOpto Semiconductors sees threemain areas for growth in the shorter term.The first of these is outdoor lighting, includingstreets, roadways, parking lots and tunnels;the second is professional indoor lighting,including offices and retail; and thethird is LED retrofits.Looking further ahead, residential lightingwill clearly become a major market. Thisis connected to building and design cycles,and the buying decision is based much moreon an emotional response, providing whatthe customer actually likes, for examplesparkling light and vivid colors. This contrastswith the current growth markets,where there is usually some form of milestoneor performance criteria that need tobe met, for example energy-efficiency targetsor specific light distribution patterns.For outdoor applications, the abilityto provide cool white LEDs with a performancelevel of ~100 lm/W has createda sweet spot that is now being exploited.There is a great deal of momentum, particularlyin Asia, where a huge amount of newinfrastructure is being installed. Anotherfactor is that many Asian countries arecomfortable with cool-white light, whereefficiency is best. We have been involved ina number of trial street-lighting installations,perhaps 20 to 30 poles at a time. Nowthis is becoming a volume business. Lifecyclecost calculations are the overriding factor,and the total cost of ownership must bebelow five years.In tunnel lighting applications, LEDs providelong lifetime and low maintenance, aswell as much better color rendering, whichis very important in emergency situations.For example, after an accident, it would bevery important to tell whether a spilt liquidwas blood or fuel.For professional lighting, a major factor isdirectionality — the ability to put the lightwhere it is required, for example to illuminatea desk or work surface. LEDs eliminatereflector designs, and officelighting power densities canbe cut in half. Success requiresprofessional fixtures that arebuilt from scratch, in order totake advantage of the propertiesof LEDs. It’s possible toachieve 60 lm/W at the systemlevel, and this compares verywell to existing technologies.Studies need to be madeinto human acceptance ofLED lighting in professionalenvironments — looking for example at theeffect of different illuminance levels in differentareas — and results need to be incorporatedinto standards. In modern building,LED lighting is likely to be part of an overallsolution that includes adaptive lighting anddaylight control.Project and customer feedbackWe are at the stage where LEDs have beenincorporated into fixtures that have beendeployed in reference projects, and we arenow receiving feedback from these projects.With each project, the argument for LEDsbecomes stronger.The LED retrofit market is clearly veryimportant, although such applicationsdon’t harvest the full potential of LED capabilitiesand performance. Current LED retrofitsstruggle with price and performanceissues; it’s possible to have good performanceor low cost, but usually you can’t find bothtogether.In terms of performance, color quality isa top priority for our company, and we areworking on areas such as color-conversion(phosphor) technology andtailoring the spectral output,as well as binning andconsistency. As a semiconductormanufacturer, ourcompany benefits from economiesof scale, so that as thevolume grows there is scopefor price reduction. Highervolume also makes it easierfor us to deal with customrequirements, for examplespecific binning requests.These issues currently add a burden to ouroverall costs.LED lighting is characterized by low lifecyclecosts, and the potential for significantenergy savings, but with higher initial costs.One of our jobs is to convince stakeholders,such as politicians, architects, light planners,and municipalities, of the value of LEDillumination. They are definitely becomingmore receptive, but they need to see referenceprojects.Some street lighting projects have been inplace for two or three years, so these are providingresults and data, but when these wereinstalled, the efficiency of the LEDs was typicallyhalf of the values today.LED technology continues to » page 4952 APRIL 2009 LEDsmagazine.comPrevious Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | Next PageABE FMaGS

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Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | Next PageABE FMaGSCREE SETS THE STANDARD FOR ARCHITECTURAL, RESIDENTIAL, COMMERCIAL AND OUTDOOR LIGHTINGTHAT’S LIGHTING-CLASS.Built to deliver energy-effi cient beautiful light, Cree XLamp LEDs outperform allothers in brightness and effi cacy. And they prove it daily at thousands ofcommercial, architectural and residential installations worldwide.Contact a Cree Solutions Provider or authorized distributor atwww.cree.com/xlamp or call 800-533-2583.Visit Cree at Lightfair Booth #1463XLamp XR-EThe proven platform.Up to 114 lumensat 350 mAXLamp MC-EUp to 456 lumensat 350 mA —4x the fl ux, samesize as an XR-E.XLamp XP-ESame output asthe XR-E at 20%the package size.Photos depict actual installations using Cree XLamp LEDs. Cree, the Cree logo and XLamp are registered trademarks of Cree, Inc.Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | Next PageABE FMaGS