Patent ID: 7798677

Claim:
An illumination unit for emitting light along an optic axis for a projection system comprising: an LED die; and a collimator lens comprising: a central part having a first light transmission surface and a second light transmission surface opposite to the first light transmission surface; and a peripheral part around the central part having an inner refraction wall coupled to the first light transmission surface to form a hollow for situating the LED die, an outer reflection wall opposite to the inner refraction wall, and a refraction surface connecting to the second light transmission surface and the outer reflection wall, wherein both the central part and the peripheral part of the collimator lens are rotationally asymmetrical corresponding to the optic axis; the peripheral part having a refraction surface the section of which has a curved top surface that connects to the central part on one side and to a flat surface at an acute, downward facing angle on the opposite side, the flat surface connecting to the outer reflection wall.