| 摘要 |
PROBLEM TO BE SOLVED: To provide a high light emitting efficiency by forming reflecting surfaces forming an irregular pattern of surfaces crossing each other at a predetermined angle, and providing the crossing surfaces on a surface of a light guide plate at a right angle so that a flat surface, which equally divides the crossing angle into two, passes through a light source. SOLUTION: A reflecting surface forming an irregular pattern 15 is formed into a prism shape. Surfaces of a rectangular prism 15a crossing each other are provided so that a flat surface, which equally divide the cross angle into two, passes a spot light source 13 and crosses a surface of a light guide plate 12 at a right angle. The irregular pattern 15 is formed so that a light source side surface thereof is formed at 45 degree in relation to a surface of the light guide plate 12, and an angle formed by the rectangular prism 15a and the surface of the light guide plate 12 is set at 33.75 degree. When the light enters the rectangular prism 15a at a right angle, the light is reflected to the opposite direction, and even in the case where the rectangular prism 15a is inclined, if it is not inclined from over, the total reflection angle is maintained so as to reflect the incident light. Consequently, the total reflection is generated by the rectangular prism 15a. |
