Back light module with birefringent crystal assemblies

摘要

A back light module (100) includes a light guide plate (130), a number of light sources (110) at one side of the light guide plate, and a number of birefringent crystal assemblies (120) respectively located between the light sources and the side of the light guide plate. Each birefringent crystal assembly includes a generally wedge-shaped first birefringent crystal (121) and a generally wedge-shaped second birefringent crystal (122) adhered to each other back-to-back. The birefringent crystal assembly enlarges a radiation angle of optical beams emitted from the corresponding light source. The optical beams with enlarged radiation angles enter the side of the light guide plate, and help provide excellent uniformity of brightness to an associated liquid crystal display panel.