Abstract: This Experiment was carried to investigate the effects of theluminance contrast between the symbols and background of VDT. Usingaccommodation and convergence time of eyes and the performance ofreading symbols, eight luminance contrasts ranging from 3: 1 to 18: 1 werecompared. It was confirmed that when the luminance of background wasabout 20cd/m~2, the optimum contrast range was about from 8: 1 to 12: 1and the permitted luminance contrast range was from 4: 1 to 18: 1.

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