le travail à l'écran de visualisation work with display units

CENTRAL PROGRAMME FOR BETTER VDU CONDITIONSK-G Lindstrôm, the Board of Occupational Safety and Health for Government Employees(SAN) and Bo Claeson, Swedish Foundation for Occupational Health & Safety for StateEmployees, Stockholm, Sweden.The public debate on the link between well-being and health in work at video display units(VDU's) has been lively in Sweden in recent years. The debate initially concerned the questionof whether work at a VDU represented a hazard to pregnancy. Other issues have graduallyemerged. Now questions are being raised about whether VDU work is capable of causing eyeproblems, skin complaints and overload injuries plus mental strain or psychosomaticcomplaints or injuries.The research results continuously published on these issues sometimes seems contradictory ordiffuse. As a result, many people who work at VDU's are becoming concerned about theirhealth and demanding unequivocal information about what we know for certain in thesematters and advice about the way of arranging VDU work to prevent the development ofproblems.SAN and Swedish Foundation for Occupational Health & Safety for State Employees arejointly publishing a booklet in the beginning of 1989 supplying the desired information andadvice. The booklet also contains a policy statement on work at a VDU. The booklet wasprepared by the central parties on the public sector labour market. This policy statement onlocal work environment efforts in the public sector offers the following advice to publicagencies and authorities:- Prepare an action plan showing how intensive, repetitive and severely constrained VDUwork can be avoided or limited. This also applies to systems already in use.- Develop work content and the work organization whenever changes in activities areintroduced.- Ensure that employees have an opportunity to develop their competence to a degree enablingthem to participate in modification work.- Ensure that the people affected participate in modification work right from the start.These policy points can be viewed as a central action programme for the entire public, labourmarket sector. The approach is in accordance with the "Scandinavian Model" in the sense thatit is based on unity and the cooperation of the parties. The value of the programme depends onwhether it achieves any practical results and leads to improvements in the work environment atVDU. At the time of writing, a follow-up and evaluation of the programme are being plannedwith such practical results as the starting point. We expect that we can give the first results ofthis follow-up in September 1989.VDT REFLECTION CONTROL: PROPOSED ISO STANDARD 9241/7John M. Cone, Monitor Products Advanced Technology, IBM Corporation, Department H29/205, PostOffice Box 12195, Research Triangle Park, North Carolina, USA.Reflections from the screen of a VDT reduce the contrast of the information displayed. Sharp details in thereflection may interfere with perception of the information displayed, and certainly cause distraction. Botheffects may adversely affect the visual ergonomics of VDTs. ISO Technical Committe 159, Subcommittee 4,Working Group 2, is charged with formulating VDT ergonomics standards, and has decided that it would beappropriate to standardize minimum requirements for the control of reflection.One requirement already exists in ISO Draft International Standard 9241/3: that whatever the contrast orreflection control method, the VDT must continue to meet all visual requirements.. Additional requirementsare contained in a new draft submitted to ISO TC 159, SC4, WG2 for consideration as a Draft Proposal.The draft has two main performance requirements:1. The inner contrast of characters on a VDT screen must meetC m(LF max) ^in the center of the reflected virtual image of a specified luminous source of veiling reflections under standardillumination.2. The reflected contrast of high-spatial-frequency details of a specified luminous grating source must bewithinC m(HF max) -orxC m(LF max)Cm(HF max) - 0-174 X C m(LF max )of the character inner contrast measured in the first requirement, depending on the measurement methodchosen.Although these requirements are easily stated, the measurements required to see that they are met must beperformed under very precisely controlled conditions* This is because:1. The specular reflectance of VDT surfaces changes as a function of the angle of incidence of light.2. The effective diffuse reflectance of VDT screens changes as a function of the angle of incidence of light.3. Some VDT anti-reflection treatments and materials, and some display technologies, have very restrictedangles of optical transmission.4. The test grating chosen for the high-spatial-frequency contrast test should be based on the high-spatialfrequencycontent of the VDT, and should allow for screen curvature.5. Devices used to help measure reflections can introduce stray light and cause measurement artifacts.This paper will outline the performance requirements and measurement procedures of the proposed draft ofISO standard 9241/7.KEYWORDS: Standards, reflection, visionKey words: Policy, Programme, HealthTEV 1989 -DEUXIÈME CONFÉRENCE SCIENTIFIQUE INTERNATIONALE • MONTRÉAL • SECOND INTERNATIONAL SCIENTIFIC CONFERENCE - WDU 1989170TEV 1989— DEUXIÈME CONFÉRENCE SCIENTIFIQUE INTERNATIONALE • MONTRÉAL • SECOND INTERNATIONAL SCIENTIFIC CONFERENCE — WWDU 1989171