| 摘要 |
PROBLEM TO BE SOLVED: To uniformly control the light quantity of light from the exit face of a light transmission plate to the external over the whole area and to uniformly maintain the luminance by changing the area of dots only on a part of an irregular reflection surface in accordance with the distance from a light source. SOLUTION: Light made incident from a light source 2 upon the inside of the light transmission plate 7 reaching a dot group 8 is scattered to the inside of the plate 7 and a part of light is projected from the exit face of the plate 7 to the external. When the area of only a part of dots included in the dot group 8 on the irregular reflection surface is changed in accordance with the distance from the light source 2, the areas of respective dots included in the dot group 8 can be defined so that the light quantity of light from the exit face of the plate 7 to the outside is uniformly controlled over the whole area of the exit face. Consequently generation of luminescent lines on the light source side exit face of the plate 7 can be prevented and luminance can be uniformly maintained over the whole area of the exit face of the plate 7. Thereby unevenness is not generated on a liquid crystal screen and quality display can be obtained. |
