Relation between Short-Term and Long-Term Assessment of Glare
The utilization of LEDs in general lighting applications,including office lighting,is accelerated by the LEDs advantages,such as a high luminous efficiency,low power consumption,and long lifetime.One disadvantage of LEDs,however,is the perceived glare as a consequence of a high brightness emitted from a relatively small light-emitting area.For example,in offices light from high-intensity LED-based luminaires in the ceiling may stray light into humans eyes,and as such cause discomfort glare.Understanding the seriousness of discomfort glare in typical office conditions is very important in relation to the design of new LED-based luminaires.Therefore,we investigated glare perceived from an experimental luminaira,consisting of a 7×7 matrix array of small LED sources,which in part of the experiment was uncovered and in part of the experiment covered with a diffuser.Twelve of these luminaires illuminated the experimental room,in which we centrally placed four large tables.The intensity of the luminaires was varied in order to determine the relation with perceived glare.As typically done in most glare-related experiments,we performed a short-term assessment,in which the subjects were asked to score the perceived glare after a one-minute task on a laptop.Two scoring methods were used:(1) a seven-point rating scale,ranging from Imperceptible to Intolerable,and (2) the question whether the subjects considered the lighting condition comfortable or not.Next to the short-term experiment we performed a long-term experiment for one particular lighting condition:i.e.,for an illuminance on the tables of 5301ux with a difference smaller than 3.6%.The long-term experiment included two sessions:in one session subjects were asked to do their own work using a laptop for 2 hours and in the other session subjects were asked to have a meeting in the room for 2 hours.Apart from perceived glare,also the general fatigue of the participants was measured with a questionnaire before and after each session of the long-term experiment.In total 32 subjects participated in the long-term experiment,with 16 participants in each session.These same subjects also performed the short-term experiment.The results on perceived glare obtained after a long exposure time (i.e.,2 hours) are consistent with those obtained after a short exposure time (i.e.,1 minute).This seems to reduce the need for long-term exposure experiments,although 2 hours of exposure may still be too short to measure adverse effects.We also didnt find a difference in reported glare between laptop work and a meeting,suggesting that the particular setting to measure glare exposure is not so important.Adding a diffuser to the LED luminaire significantly reduced perceived glare,and as a result more than 75% of the people found the luminaire comfortable (for an intensity level corresponding to 530 lux at the table).Some symptoms of eye fatigueincreased during the experiment,but their relation with the lighting condition still needs further research.
LED luminaire discomfort glare glare evaluation
Yan Tu Jihuang Zhang Fan Lu Lu Liu Lili Wang Sheng Peng Ingrid Heynderickx
Dong Fei R&D Centre, School of Electronic Science and Engineering, Southeast University, Nanjing, P. Philips Research Asia-Shanghai, P.R.China Philips Research Laboratories, Eindhoven, and Technical University Delft, the Netherlands
国际会议
9th China International Forum on Solid State Lighting(第九届中国国际半导体照明论坛)
广州
英文
319-319
2012-11-05（万方平台首次上网日期，不代表论文的发表时间）