Patent ID: 8480284

Claim:
A light guide unit, comprising: a light guide plate having a first surface, a second surface opposite to the first surface, and a light incident surface connecting the first surface and the second surface, wherein the light incident surface comprises a first recess and a second recess arranged in a sequence from the first surface to the second surface, and an average radius of curvature of the first recess is less than an average radius of curvature of the second recess, wherein the first recess comprises: a first portion disposed between the first surface and a first reference plane, wherein a distance from the first reference plane to the first surface divided by a distance from the first reference plane to the second surface is substantially equal to ⅓; and a second portion disposed between the first reference plane and a second reference plane, wherein a distance from the second reference plane to the first surface divided by a distance from the second reference plane to the second surface is substantially equal to 1, and the second recess comprises: a third portion disposed between the second reference plane and a third reference plane, wherein a distance from the third reference plane to the first surface divided by a distance from the third reference plane to the second surface is substantially equal to 3; and a fourth portion disposed between the third reference plane and the second surface, wherein the first reference plane, the second reference plane, and the third reference plane are substantially parallel to the first surface, and an average radius of curvature of the first portion is less than an average radius of curvature of the second portion, the average radius of curvature of the second portion is less than an average radius of curvature of the third portion, and the average radius of curvature of the third portion is less than an average radius of curvature of the fourth portion, wherein the first recess is asymmetrical on a direction perpendicular to the first surface, and the second recess is asymmetrical on the direction perpendicular to the first surface; and a scattering reflective unit disposed on the second surface.