| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a surface light source device whose light use efficiency is not much degraded even with a smaller light guide portion formed thicker than a light guide plate body. <P>SOLUTION: At an end of the light guide body 64 in the light guide plate 63, the light guide portion 65 that is thicker than the light guide plate body 64 is provided. A point light source 62 is disposed to face an end surface (a light incident end surface 66) of the light guide portion 65. The light guide portion 65 is thicker at a projection having a form of half cone trapezoid projecting from a surface of the light guide plate 63. The outer peripheral surface of the projection is formed as a sloping surface 67. On the sloping surface 67, V-shaped groove structures 68a are arranged along the outer peripheral surface of the projection to form a directional conversion pattern 68. Furthermore, at the inner circumference portion of the directional conversion pattern 68, an auxiliary sloping surface 71 sloping at a smaller angle than the sloping surface 67 is formed along the inner circumference edge of the directional conversion pattern 68. <P>COPYRIGHT: (C)2010,JPO&INPIT |
