Spread illumination apparatus

摘要

The invention describes a light reflection pattern to spread the volume of the emitted light from a bar-like light source with a plurality of grooves provided along a transparent substrate and plane portions adjacent to the grooves. By setting the inclined angle of the grooves along the transparent substrate the light is introduced with a high efficiency to a liquid crystal display device in the direction perpendicular to the substrate. By restricting the ratio of the width of the grooves to the pitch that is the occupied area in the range of 0.01-0.15 (preferably 0.01-0.1) the ratio becomes one in which the duplicate image component is not recognized by the naked eyes while image brightness is maintained.