Introduction of using Unified Glare Rating for visual comfort evaluation considering the brightness difference between VDT and its ambience

In order to determine a more comfortable brightness of a video display terminal (VDT), a preliminary investigation was carried out. The result shows the difference of brightness between VDT and ambient, as a factor used to affect visual comfort, is more important than brightness of VDT. For lamp system, Unified Glare Rating (UGR) is used to evaluate the influence of luminous on visual comfort. In this paper, an formula to evaluate the influence of the difference of the display equipment and the ambient brightness on visual comfort of VDT is introduced. The evaluation formula are verified by a test of 20 sample and proved to be basically feasible. More experiments will be carried out in order to get further validation or more correction factors.