Yoshihiko Ohtani

On the Simple Prediction Method for Luminance Distribution on Luminous Surfaces of Lit Sign

In the luminance distribution of a lit sign, having no irregularities in brightness is desirable, that is, the uniformity ratio of the luminance should be good. The uniformity ratio is decided by various factors such as the number of lamps, the spacing of the lamps, the distance between the light source and the luminous surface, the inner surface reflectance, and the luminous surface reflectance. A simple prediction method to obtain the relationship between these factors and the uniformity ratio of the luminance was tested by using calculations on a two-dimensional surface. We found that the method was suitable, because the calculated and experimental results agreed with each other.

On a measurement method of configuration factor distributions with the help of an electronic still camera and a personal computer

Abstract In the field of daylighting design, the configuration factor is widely used as an index of the brightness because it is not affected by variation of illuminance. Therefore, the authors developed a method to measure the configuration factor distribution by using several still video images taken by the electronic still camera. More by this method, the configuration factor can be obtained more simply and exactly moreover in a shorter time. This paper describes the outline of this measurement method.