Abstract We examine the effect of the (luminance) ratio of ambient luminance to tablet surface luminance on text legibility and fatigue over 1 h of long-term reading with a tablet PC in low-ambient-luminance environments limited to 45 cd/m2 (illuminance ∼ 230 lx). Four reading-pattern subject experiments are carried out at ambient-luminance-to-tablet-surface-luminance ratios of 1:1, 1:3, 1:6, and 1:9 at 15 and 45 cd/m2. As per legibility tests based on the semantic differential (SD) method, we find that subjects experience glare at luminance ratios of 1:6 and 1:9, and it is difficult to read text at the luminance ratio of 1:9 under ambient luminances of 15 and 45 cd/m2. Based on subject fatigue (determined by subjective symptom survey), we find that the feeling of fatigue, according to the change in the luminance ratio, most affects the Fuzziness group among the five subjective fatigue groups. Based on physical fatigue determined using the critical flicker fusion frequency (CFF) value, we observe significant CFF differences before and after reading for luminance ratios of 1:1 and 1:9 at the ambient luminance of 45 cd/m2 and for the ratio of 1:9 when the ambient luminance is 15 cd/m2. A larger difference between the ambient and surface luminances corresponds to higher CFF variation rates and more fatigue.

中文翻译：

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环境-平板电脑亮度比对低光照环境下长期阅读时易读性和视觉疲劳的影响

摘要 我们研究了环境亮度与平板电脑表面亮度的（亮度）比对文本易读性的影响，以及在限制为 45 cd/m2（照度）的低环境亮度环境中使用平板电脑在 1 小时内长期阅读疲劳的影响。 ∼ 230 lx)。在 15 和 45 cd/m2 下，以 1:1、1:3、1:6 和 1:9 的环境亮度与平板电脑表面亮度比进行了四个读取模式主题实验。根据基于语义差异（SD）方法的易读性测试，我们发现主体在亮度比为 1:6 和 1:9 时会感到眩光，并且在环境亮度下亮度比为 1:9 时难以阅读文本15 和 45 cd/m2。基于受试者疲劳（通过主观症状调查确定），我们发现疲劳感，根据亮度比的变化，在五个主观疲劳组中，对 Fuzziness 组的影响最大。基于使用临界闪烁融合频率 (CFF) 值确定的身体疲劳，我们观察到在 45 cd/m2 环境亮度下，亮度比为 1:1 和 1:9 时，读取前后的显着 CFF 差异，以及环境亮度为 15 cd/m2 时为 1:9。环境亮度和表面亮度之间的较大差异对应于更高的 CFF 变化率和更多的疲劳。