| 摘要 |
PROBLEM TO BE SOLVED: To decrease the weight of a surface light source and a backlight optical system by using a light guide plate, having a form which can be easily produced and which can be made light in weight, while controlling the light quantity to be uniform. SOLUTION: In the surface light source, consisting of light source devices 3, 5 and a light guide plate 2 having a light diffusing pattern 6 formed on the inclined face (or upper face 12), the inclined face of the light guide plate 2 is formed into a shaped face by constituting from a plurality of planes 13a, 13b to decrease the weight. The light-diffusing pattern rate 6 is changed discontinuously in the border 10 (or in the part of the upper surface 12 facing the border 10) of the respective flat faces 13a, 13b and the light diffusing pattern rate for making the light quantity uniform is controlled independently in each plane. The light guide plate can be produced readily, because the light guide plate has a joined form of a plurality of wedge light guide parts 11a, 11b. |
