Patent ID: 7810983

Claim:
An optical plate comprising: at least one transparent plate unit having: a first surface, wherein the first surface is flat; a second surface opposite to the first surface; a plurality of enclosing V-shaped protrusions formed on the first surface; a plurality of groups of spherical protrusions formed on the second surface; and at least one lamp-receiving portion defined in at least one of the first surface and the second surface, wherein the at least one lamp-receiving portion is a through hole communicating between the first surface and the second surface; the spherical protrusions in each group are arranged on a same circle; a center of each circle substantially aligns with a center of the at least one lamp-receiving portion; a diameter of each spherical protrusion increases along a receding direction from the at least one lamp-receiving portion; each enclosing V-shaped protrusion forms a square wall surrounding the at least one lamp-receiving portion; and top tips of each of the enclosing V-shaped protrusions are positioned in a same plane that is parallel to the first surface.