| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a planar light source enabled to further restrain a brightness unevenness and attain a further even brightness distribution and a high visual field angle. <P>SOLUTION: One end face of a light guide plate 3 is made a light incident end face 3a, at a center part of which, a light source chip 2 is arranged and light is made to enter inside the light guide plate 3 from that position. A plurality of prisms 4 in an arc shape is fitted in concentricity on a face contrary to a light-emitting face 3b of the light guide plate 3, continued from one end face to another of the light guide plate 3. The concentric center So of the prisms is on a normal line passing the center of a luminous face 2a of the light source chip 2, offset to the side opposite to the prisms against the luminous face 2a. Moreover, the prisms 4 have a constant pitch P in a direction of the length of the light guide plate 3 (that is, a direction of the distance L from the center point So), but its depth D from a virtual plane 3c parallel with the light-emitting face 3b is made large in accordance with an increase of the distance L. <P>COPYRIGHT: (C)2004,JPO |
