| 摘要 |
In a light guide plate 63, a light introducing unit 65 having a thickness larger than that of a light guide plate body 64 is provided at an end of the light guide plate body 64. A point source of light 62 is placed so as to face an end face of the light introducing unit 65 (a light incident end face 66) . The light introducing unit 65 has a protruding portion in a shape of a half of a frustum of a cone protruding from a surface on the light guide plate 63 to have a large thickness, and the protruding portion has an outer perimeter surface forming an inclined surface 67. On the inclined surface 67, V-groove structures 68a are arranged along the outer perimeter surface of the protruding portion to configure a directivity conversion pattern 68. Furthermore, on an inner perimeter portion of the directivity conversion pattern 68, an auxiliary inclined surface 71 having an angle of inclination smaller than the angle of inclination of the inclined surface 67 is formed along an inner perimeter edge of the directivity conversion pattern 68.
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