Fundamental study of shadow characteristics under Task Ambient Lighting

Abstract

Shadow is something we experience in our daily lives and a significant obstacle to our work. So shadow has been considered one of the important factors in lighting design. In this paper, the illuminance distributions on a desk as the working plane when Task Ambient Lighting, which is one type of office lighting systems, and a globe as a shadow caster are set up in a model room containing fixtures are obtained by the Monte Carlo method and the characteristics of the shadow are examined. First, in order to carry out the illuminance calculation by the Monte Carlo method in the case of a light source with a non-uniform diffuse distribution, the relationship between the cumulative luminous flux and uniform random numbers was found by the use of division mensuration. Next, some experiments were made under the same conditions as the calculations. Comparing the experimental results with the calculated results, difference between them, confirms that the above method is suitable. Then, we obtained and examined the shadow characteristics on the surface of the desk when the position of the shadow caster was changed. As a result, we found that Task Ambient Light makes a weaker shadow than one of Task light or Ambient light, and variations in the shadow area by Task Ambient Light are similar to those by Task light. Copyright © 2007 The Illuminating Engineering Institute of Japan.