Patent ID: 7374329

Claim:
A light guide device, comprising: a main body, including: a first incident surface; a second opposite incident surface; an emitting surface extending from the first incident surface to the second incident surface; a reflecting surface opposite from the emitting surface; and a plurality of first microstructures formed on the reflecting surface, each first microstructure extending parallel to the first and second incident surfaces, the first microstructures having a distribution density and a relative size, the distribution density and the relative size progressively decreasing along directions from a center of the reflecting surface toward the first and second incident surfaces, respectively, wherein each of the first microstructures comprises a triangular cross-section having a first base angle that is approximately in the range from 70 to 90 degrees, a second base angle that is approximately in the range from 15 to 50 degrees, and a vertex angle that is approximately in the range from 40 to 95 degrees.