| 摘要 |
PROBLEM TO BE SOLVED: To provide a light guide plate, a surface light source device and a transmission type display device having excellent in-plane evenness of brightness.SOLUTION: A light guide plate 13 is configured by arranging, in a light guide direction, a plurality of back surface side unit optical shapes 131 each of which includes a first slope part 132 located on the light incident surface side, a second slope part 133 located on the other side and totally reflecting at least a part of incident light and a top surface part 134. The ratio Wd/P1 of a dimension Wd of the second slope part 133 in the light guide direction to an array pitch P1 of the back surface side unit optical shape 131 is changed in the light guide direction, exhibits the minimum value in the light incident surface side, the ratio Wd/P1 on the light incident surface 13a side rather than the back surface side unit optical shapes 131 which exhibits the minimum value is larger than the minimum value, and the ratio Wd/P1 on the opposite surface 13b side rather than the back surface side unit optical shape 131 which exhibits the minimum value is enlarged as approaching the opposite surface 13b side. |
