| 摘要 |
PROBLEM TO BE SOLVED: To provide a surface light source unit of high brightness, a back light device and a liquid crystal display device using the same. SOLUTION: A surface light source unit LF is equipped with a light guide plate 1 that has a light deriving means 1a composed of a plurality of protruded strips 1a1 in front. The unit LF is equipped with at least one sheet of optical path correcting sheets 2, 3, with the backs of which being flat, with a plurality of strips of prisms 2a, 3a being arranged in front, and with the back of which being directly optically arranged opposite the front of the light guide plate 1. Since an optical path of output light that is condensed from the light guide plate 1 at low angle of 50 deg. or less is corrected by the optical path correcting sheets 2, 3, surface emission of 90±10 deg. is obtained in high brightness. The back light device BL is made up of the surface light source unit LF, a light source LS and a lighting circuit. |
