Edge-type back-lighting device for a display

摘要

There is provided a lighting panel having two rectangular surfaces opposing each other one of which is a reflection surface and t he other is a discharge surface, an edge light provided at a corner of the lighting panel. A plurality of planar prisms with a triangular base are circularly formed on the reflection surface of the lighting panel, centering the edge light. Each of the prisms has a vertical angle &thetas; comprising a first inclination angle &thetas;1 with respect to the normal to the panel surface on the edge light side and a second inclination angle &thetas;2 with respect to the normal to the panel surface opposite to the first inclination angle &thetas;1. There is a following relationship between the first inclination angle &thetas;1 and the second inclination angle &thetas;2. &thetas;1 > &thetas;2 and 60 DEG ≤&thetas;1 ≤ 89,5 DEG .