| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a surface lighting device which prevents nonuniformity in brightness from occurring in the neighborhood of a positioning projection formed on a light guide plate and can make brightness uniform all over an output surface. <P>SOLUTION: Protrusions 11a, 11b, 11c, 12a, 12b, 12c are formed on sides 11, 12 of a light guide plate 1 to position the light guide plate 1 to a frame body 7. Recesses 20a, 20b, 20c, 21a, 21b, 21c are formed on the frame body 7 for housing the light guide plate 1 corresponding to the protrusions on the light guiding plate 1, respectively. Notches 13a, 13b, 13c, 14a, 14b, 14c are formed at the ends of the respective protrusions far away from LEDs 2. The recess is formed into a rectangular shape. A notch is formed into a shape with an edge of a protrusion cut into a plane (corner-chamfered) or into a shape with the edge round (round-chamfered), where the protrusion has the same shape as the recessed part in a rectangular shape. This reduces the amount of the light which proceeds to the center of the light guide plate 1 after reflecting at the sides of the protrusions plural times, and prevents nonuniformity in brightness from occurring in the neighborhood of the protrusion. <P>COPYRIGHT: (C)2006,JPO&NCIPI |
