WEDGE-SHAPED LIGHT GUIDE PLATE FOR FRONT LIGHT

摘要

PURPOSE: To provide a wedge-shaped light guide plate for a front light which can uniformize luminance distribution. CONSTITUTION: A light guide plate 4 has a nearly wedge-shaped cross section orthogonal to an incident plane 4a. A groove 7 is constructed by an inclined plane 5 which forms an angle β to a light-emitting plane 4c and a light collection plane 6 which forms an angle α to the light-emitting plane 4c. The mountain 8 and the valley 9 of each groove are formed by the inclined plane 5 and the light collection plane 6, and a pitch P between the bottoms of the valleys 9 is uniformly set. When the groove 7 between the incident plane and the end at the opposite plane 4b side is seen from an end at the incident plane 4a side, a groove depth dm does not decrease from the incident plane 4a side, and preferably increase monotonously from the incident plane 4a side. When the groove depths dm of adjacent grooves 7 are compared, the variation of the groove depths dm does not decrease, and the maximum variation is preferably less than 2% when compared with a side with a small groove depth dm.