| 摘要 |
<P>PROBLEM TO BE SOLVED: To improve uneven brightness in a planar lighting device while preventing increase of manufacturing cost and decrease in front brightness, and to extinguish bright lines in the vicinity of an incident surface. <P>SOLUTION: In the planar lighting device, the uneven brightness is improved and the bright lines in the vicinity of the incident surface is extinguished with wave-prisms 11w included in an area Aw in a light source-side of an optical axis direction. Since the other area only includes straight prisms 11s, the front brightness of such an area is as good as that of the conventional guide plate only including straight prisms, and processing man-hour is also to be same as that of the conventional light guide plate. Since the positions where the wave-prism 11w transfers to the straight-prism 11s in the optical axis direction are randomly arranged for every part 11d of multiple protruded line parts, it is possible to prevent generation of so-called visible streaks which shine in the streak shape as a whole at the boundary of the wave-prism 11w and the straight-prism 11s generated by the brightness differences between them. <P>COPYRIGHT: (C)2012,JPO&INPIT |
