照明の変動知覚における変化前予告と照明位置の影響に関する研究

<p> In our research on the perception of illumination change, we conducted an experiment that incorporated as factors a warning signal before a change of lighting and various lighting positions. We analyzed the perceptual characteristics of each factor under situations that are similar to actual work spaces, and also examined the dimming method of variable lighting that is comfortable for the employees’ working environment by analyzing the results together with the findings of previous research.</p><p> In Experiment 1, general lights were installed at three locations directly above each seat, and the lighting was continuously dimmed with a dimmer. In Experiment 2, lighting positions were added that could be moved obliquely or laterally in order to examine the effect in situations where the positional relationships between the worker and the lighting were similar to those of actual working spaces. In addition, LED lamps were installed under each general light that gave a warning signal about 10 seconds before a lighting change. This process was explained to the subjects at the start of the experiment. The subjects were asked to do office work combining writing and visual-display terminal work, and to answer a questionnaire each time they noticed a change in lighting brightness while working. They answered the questionnaire about how the brightness of the interior space and desk surface changed by selecting one of three choices (brighter / darker / no change). They were also asked if they were concerned about the change (their degree of concern about the brightness change) using the seven-step semantic differential method.</p><p> From the experiment results, the following findings were obtained.</p><p> 1) Regarding warning before a change of lighting, it was found that the perception rate and degree of concern about the brightness change were low for the lighting of the seat on the separate work island. The result suggests the possibility that in actual offices where worker’s sitting down and standing up is accompanied by changes in lighting, the effects of a change in brightness at a location away from the worker may be less than the perceived rate and degree of concern obtained in previous studies.</p><p> 2) It has been shown that not only a change in illuminance but also the magnitude of the change in the subject's visual field affects the perception. In addition, it has been found that the change is more noticeable at the time of increasing the lighting than at the time of dimming the lighting.</p><p> 3) Based on the related research results, including this research, it has been found that the degree of concern of a worker about a change in brightness of fluctuating lighting is correlated with the amount of change of illuminance (the amount of change in illuminance per unit time, lx/s), and when the starting illuminance is 750 lx, a change is more likely to be noticed at a change amount of 20 lx/s or more.</p>