Patent ID: 7798681

Claim:
A light guide block comprising: a polygonal light exit surface; an octagonal bottom surface opposite to the light exit surface with a receiving hole formed therein, the receiving hole being configured for receiving a light source therein; and a peripheral stepped side surface substantially interconnecting the light exit surface and the bottom surface, the light guide block generally tapering from the light exit surface to the bottom surface, wherein the peripheral stepped side surface comprises a plurality of first side surfaces and a plurality of second side surfaces, each of the first side surfaces defines a substantially isosceles trapezoidal shape, each of the second side surfaces defines a substantially isosceles trapezoidal main portion and a substantially triangular minor portion, the substantially isosceles trapezoidal shapes of the first side surfaces and the substantial isosceles trapezoidal main portions of the second side surfaces are alternately arranged around a center axis of the light guide block, and each substantially triangular minor portion extends from the long parallel side of the corresponding substantially isosceles trapezoidal main portion to a corresponding corner of the light exit surface.