| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a planar lighting device of sidelight type capable of expanding uniform region of luminance of emitting light and improving its average luminance, while containing enlargement of the device. <P>SOLUTION: The planar lighting device 10 is a sidelight type planar lighting device having a light guide plate 12 and light sources 17, 18 which are arranged along two opposed side end faces 13, 15 of the light guide plate 12, and is provided with a double-sided prism sheet 14 that is arranged on the emission face 19 side of the light guide plate 12. The rear face 20 of the light guide plate 12 includes a first region 22 in which an optical path changing means 21 is not formed and a second region 24 in which the optical path changing means 21 is formed, and a prescribed length B in light guide direction of the first region 21 satisfies relations of 0<B<(X-Y)/2 with the total length X in light guide direction of the light guide plate 12 and the length Y in light guide direction of an effective area 28 of the emission face 20. <P>COPYRIGHT: (C)2013,JPO&INPIT |
