Patent ID: 8491176

Claim:
A light guide plate, comprising: a first surface; a second surface, opposite to the first surface, wherein the first surface is a light-emitting surface; and a plurality of light incident surfaces, connecting the first surface and the second surface, wherein the second surface has a plurality of ring-shaped grooves, depths of the ring-shaped grooves are gradually decreased from a place close to a center of the light guide plate towards places close to the light incident surfaces, and each of the ring-shaped grooves has: a first ring-shaped side wall surface; and a second ring-shaped side wall surface, wherein the second ring-shaped side wall surface is opposite to the first ring-shaped side wall surface, the second ring-shaped side wall surface is located between a geometry center of the ring-shaped groove and the first ring-shaped side wall surface, the first ring-shaped side wall surface is a tilted surface, and an included angle between a normal vector of the first ring-shaped side wall surface and a normal vector of the first surface is greater than 90°.