| 摘要 |
On the side surface of an optical guide plate (104), an engaging protrusion (105) is formed for fixing the optical guide plate (104) on to a frame (101) by fitting the optical guide plate in a recessed portion formed on the frame. The light emitted from an LED (107) enters the optical guide plate (104) from a light-incident end surface and travels in the optical guide plate (104) while spreading in a fan-shape. The engaging protrusion (105) is formed outside the outgoing-angle range of the beam (109) spreading in the fan-shape, thereby preventing occurrence of bright line caused by reflection of light at the corner portion of the base of the engaging protrusion (105).
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