| 摘要 |
PROBLEM TO BE SOLVED: To provide a screen easy to see the peripheral part for a person seeing the screen on the middle position of screen by making most of transmitted light from each position of a light guide plate travel toward the middle. SOLUTION: Light is transmitted from an exit surface (the surface of a diffusion prism 11a (12a)) in which many fine diffusion grooves are parallely provided. The cross sectional shape in the orthogonal direction to the diffusion groove of the surface of the diffusion groove is formed with the equilateral sides b00, b01 of the isosceles triangle whose vertex angle is an obtuse angle in the middle part b0 and formed with two sides of a saw-shaped triangle whose side b20, having the acute vertex angle and corresponding to the groove surface forming a slope for bending most of the transmitted light in the direction of middle part, is longer than the side b21 corresponding to the groove surface forming a slope not transmitting most of the transmitted light in the direction of middle part. |
