Patent ID: 9010984
Filing Date: 2015-04-21
Classification: G02B

Abstract:
1. A spread illuminating apparatus comprising: a light guide plate that emits light which has entered from side end surfaces from an emitting surface, which is a principal surface; light sources disposed along two side end surfaces of the light guide plate, the two side end surfaces facing to each other; and a two-sided prism sheet disposed on the emitting surface side of the light guide plate, the spread illuminating apparatus further comprising an optical path conversion unit including a plurality of linear prisms formed repeatedly in a light guide direction on a surface on the opposite side of the emitting surface of the light guide plate, the optical path conversion unit being formed to have a symmetrical shape relative to a center in the light guide direction, wherein the plurality of linear prisms each have a triangular cross-section shape, an apex angle of each of the plurality of linear prisms increases the closer the linear prism is formed to the center in the light guide direction, when a pair of inclined surfaces of each of the plurality of linear prisms is constituted by a first inclined surface that faces one of the side end surfaces at which the light sources are disposed and a second inclined surface that faces the center in the light guide direction, an inclination angle of the second inclined surface is larger than an inclination angle of the first inclined surface, and among the plurality of linear prisms, inclination angles e