| 摘要 |
PROBLEM TO BE SOLVED: To provide a surface lighting device that makes even brightness possible over the whole screen. SOLUTION: A light source part is nearly arranged along one side surface 3 of a transparent substrate 2. The light source part is composed of longitudinal light guides 7a, 7b and point light sources 9, 9' that are arranged one by one on both ends of a light guide. An optical path converting means 11a that is composed of a groove 15a and an flat part 16a is formed on one side surface 14a of the light guide 7a. Non-uniformity (dark areas A, B) due to difference in brightness occurs on a transparent substrate 2 owing to light reflected by the optical path converting means 11a of the light guide 7a. On the contrary, on the area opposite the dark area A, B on one side 14b of the light guide 7b, an optical path converting means 11b composed of a groove 15b and a flat part 16b is formed. That is to say, by overlapping the bright area due to the light guide 7b on the dark area A, B due to the light guide 7a, non- uniformity of brightness occurred on the transparent substrate 2 is controlled and even surface emission on the screen is realized. |
