DIRECT-UNDER BACKLIGHT

摘要

A thin direct-under backlight capable of realizing a high uniformity ratio of luminance by suppressing periodic unevenness of luminance on the emission surface while maintaining a high utilization ratio of light beam through contrivance in design of the direct-under backlight. In the direct-under backlight comprising a plurality of liner light sources arranged parallel, a reflector and a light diffuser, a prism array of saw-tooth cross-section is provided on at least one major surface of the light diffuser. If the vertex angle of the prism array on the light diffuser is y (degree), the distance between the centers of adjacent linear light sources is a (mm), and the distance between the center of the linear light source and the surface of the light diffuser on the light source side is b (mm), the following relation is satisfied: 80× (b/a)+15<y<180× (b/a)+70.