Illumination device having a single light source and liquid crystal display device

摘要

One major surface of a light guide plate (12) is formed, in stripe form in a plan view, with a plurality of prism grooves (14) each consisting of a slight slope and a steep slope. The inclination angles of the slight slope and the steep slope are in ranges of 1 DEG to 10 DEG and 41 DEG to 45 DEG , respectively. The width of the steep slope in the one major surface of the light guide plate increases as the position goes away from a light incident surface of the light guide plate in such a manner that the width of the steep slope amounts to 1.1 to 1.5 at a position farthest from the light incident surface if it is assumed that the width of the steep slope is equal to 1.0 at a position closest to the light incident surface.