| 摘要 |
PROBLEM TO BE SOLVED: To obtain uniform and bright emit light by more totally reflecting the incident light from a light source and emitting the rays of an exit angle to the extent of breaking the critical angle in a front surface part to the outside. SOLUTION: A rear surface part 6 of the light transmission plate 2 is provided with plural recessed shape parts P and mirror finished surface parts 6a, to totally reflect the rays introduced into the light transmission plate 2 once in the mirror-finished surface part 6a of the rear surface part 6. The totally reflected rays are totally reflected again in the slope parts in the incident end face part 3 direction of the recessed shape parts P to guide the rays in the surface part 5 direction. further, the recessed shape parts are disposed with the spacing density of the mirror finished surface parts 6a and the heights of the slope parts increasing gradually from the incident end face part 3 toward the reflection end face part 4, by which the total reflection quantity to be totally reflected in the mirror-finished surface parts 6a of the rear surface part 6 is increased gradually, and the more rays are totally reflected again in the slope parts and are introduced toward the front surface part 5 direction. Recessed shape parts P' are formed zigzag in shape in the flank part 7 direction between the two recessed shape parts P to correct the increase in the distance between the recessed shape parts P in a region near the reflection end face part 4, even with the large light transmission plate. |
