| 摘要 |
PURPOSE: To prevent the stripe of brightness and darkness peculiar to a wedged light guide plate from intensely appearing and to improve the unevenness of luminance. CONSTITUTION: As go away from a light entering end face 1A, the thickness of the light guide plate 1 becomes smaller and smaller, and the light emitting surface 1B of the light guide plate 1 is made a rough surface. Light made incident on the inside of the light guide plate 1 from the light entering end face 1A progresses while it repeatedly totally reflected because of the difference of optical density on the light emitting surface 1B and a reflecting surface 1C, and the light guided at a critical angle or under out of the light guided to the light emitting surface 1B is emitted from the light emitting surface 1B to the outside. In such a case, the light emitting surface 1B is made horizontal, while the reflecting surface 1C is inclined, so that the light having a different phase difference is emitted from the light emitting surface 1B and interferes. However, the light emitted from the light emitting surface 1B to the outside is diffused by the fine ruggedness of the light emitting surface 1B, and the strong interference of the light is prevented. |
