Patent ID: 7541723
Filing Date: 2009-06-02
Classification: F21V,G02B,G02F,H01J

Abstract:
1. A backlight comprising: a light source device; a light guide plate receiving light from said light source device; a polarization separating element disposed on one side of said light guide plate; and an interference type mirror disposed on the other side of said light guide plate; wherein said polarization separating element comprises an element which allows a first linearly polarized light having a plane of polarization including a transmission axis to transmit therethrough and a second linearly polarized light having a plane of polarization including a reflection axis to be reflected thereby; wherein said interference type mirror comprises a multi-layered structure including a plurality of layers having birefringence, and rotates the plane of polarization of the second linearly polarized light reflected by the polarization separating element, converts the second linearly polarized light into the first linearly polarized light, and makes the first linearly polarized light incident again to the polarization separation element through the light guide plate.