LIGHT GUIDE PLATE, SURFACE LIGHT SOURCE DEVICE AND LIQUID CRYSTAL DISPLAY DEVICE

摘要

PROBLEM TO BE SOLVED: To develop a light guide plate with which a light emission state hardly giving rise to the generation of partially dark parts to form shades and having excellent uniformity may be formed when the light transmission plate is used as a surface light source device and a liquid crystal display device of a bright and easily visible display may be formed and which is excellent in the utilization efficiency of light. SOLUTION: This light guide plate consists of a planar material which has at least top and under surfaces (1a and 1b) of a square shape and an incident flank (1c) consisting of the flank between the top and under surfaces and emits the incident light from the incident flank from the other of the top and under surfaces via a light exit means (A) formed on one of the top and under surfaces. The radius of curvature of corner parts 11 formed by the intersected points of the incident flank and the flanks (1e and 1f) adjacent thereto is <=0.3 mm. This surface light source device is constituted by arranging a wire-shaped light source on the incident flank of the light guide plate and this liquid crystal display device of a transmission type or reflection type or both of these types consists of at least the surface light source device and liquid crystal cells.