Abstract: This research was intended to explore the effecs of VDT luminancecontrast, illuminance and two different light sources on visual performa-nce. Results of a series of related experimental studies show that VDTluminance contrast is the major parameter affecting the speed of readingChinese characters on the VDT screen. The results also suggest that thereading speed decreases as VDT illuminance increases. In order to improvevisual performance under the condition of VDT, we could either increaseVDT luminance contrast or decrease VDT illuminance,. or both. In thelight of these results, our recommanded VDT illuminance ranges from 50to 200 lux. At this VDT illuminance level, the illuminance of the hori-zontal working plane is 70-340 lux under our experimental condition.

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