Patent ID: 6172809
Filing Date: 2001-01-09
Classification: G02B,Y10S

Abstract:
A surface light source device with a polarization function comprising:a light flux parallelizer composed of a plate shaped light scattering light guide having a scattering power uniform throughout the volume of the light scattering light guide and a wedge shaped cross section, the light flux parallelizer having a thicker end side and a light exit surface;light feed means disposed at the thicker end side of the light flux parallelizer; andlight permeable polarization separating means having reflection characteristics depending on polarization and being disposed to extend along the light exit surface of the light flux parallelizer,wherein the polarization separating means comprises a polarization separating plate made of a transparent optical material having a refractive index in a range of 1.3 to 2.0,the polarization separating means receiving light emitted from the light exit surface of the light flux parallelizer, transmitting light having a first polarization and reflecting light having a second polarization, orthogonal to the first polarization to return light having the second polarization to said light scattering light guide so that light having the second polarization has a chance of being converted into light having the first polarization by the uniform scattering power, to be transmitted through said polarization separating plate after impinging again thereupon.