| 摘要 |
PROBLEM TO BE SOLVED: To provide a light transmission plate which has excellent transparency, heat resistance and decreased luminance unevenness, to reduce the number of parts and to simplify an assembly stage of a backlight unit by constituting the light transmission plate of an alicyclic structure-contg. polymer resin and integrally molding ruggedness for light condensing on a light exit surface side. SOLUTION: The light transmission plate 1 is a member for emitting the light of the light source 2 made incident from a light incident surface 1a without the luminance unevenness from the light exit surface 1b while introducing the light in a longitudinal direction and is composed of the alicyclic structure-contg. polymer resin. The light transmission plate 1 has such a wedge shape that the thickness decreases gradually in the direction where the cross section parts increasingly from the light source 2 side. As the cross section parts from the light source 2, the incident angle θ1 to the outside of the exit surface 1b of the light transmission plate 1 falls increasingly below the critical angle. The light exit surface 1b of the light transmission plate 1 is provided with the ruggedness 11 for light condensing. The ruggedness 11 for light condensing has the function to emit the light source light emitted from the exit surface 1b of the light transmission plate 1 to the outside by directing the direction thereof toward a perpendicular direction as far as possible. |
