| 摘要 |
PROBLEM TO BE SOLVED: To provide an illuminator which keeps the picture quality of reflected lights satisfactory and whose lighting efficiency is good. SOLUTION: This illuminator is provided with a wire like light source 1 and a light transmitting body 3 at whose side face the light source 1 is arranged and whose upper surface and lower surface are roughly parallel and on whose upper surface slits 31 formed with a difference material or air are formed with a prescribed interval. In this case, when the refractive index of the transparent substrate 3, the refractive index of the material filling the slits, the angle formed by the slits and the upper surface of the substrate 3 and the visual angle of the illuminator are respectively defined as n, n1 , θand β, the light transmission body is made to satisfy θ<sin<-1> (n1 /n)-sin<-1> (1/n) sin(β)}. As a result, the great majority of lights propagating through the inside of the light transmission body are emitted from the light transmitting body 3 by total reflections on the slits 31 formed in the body 3 to be irradiated on a reflection plate 4 and the reflected lights are made incident on the body 3 again and totally reflected light transmits to an observer side in places other than the slits 31 and the reflected light does not disturb the visual field of the observer in the slit parts. |
