Backlight and display system using same

Abstract

A backlight that includes a front reflector and a back reflector that form a hollow light recycling cavity including an output surface is disclosed. The backlight further includes one or more light sources disposed to emit light into the light recycling cavity. The front reflector includes an on-axis average reflectivity of at least 90% for visible light polarized in a first plane, and an on-axis average reflectivity of at least 25% but less than 90% for visible light polarized in a second plane perpendicular to the first plane.

What is claimed is: 
     
         1 . A luminaire comprising:
 a front reflector and a back reflector that form a hollow light recycling cavity comprising an output surface; and   one or more light sources comprising multiple LEDs that emit different colors of light disposed to emit light into the light recycling cavity;   wherein the front reflector comprises a polymeric multilayer optical film having an on-axis average reflectivity of at least 65%.   
     
     
         2 . The luminaire of  claim 1  further comprising a light sensor and feedback system to detect and control white point or temperature of light from the LEDs. 
     
     
         3 . The luminaire of  claim 2  wherein one or more light sensors are located along the edge or within the light recycling cavity. 
     
     
         4 . The luminaire of  claim 1  further comprising a thermal sensor and feedback system to detect and control the output of the LEDs. 
     
     
         5 . The luminaire of  claim 1  comprising one or more side-emitting LEDs. 
     
     
         6 . The luminaire of  claim 1  wherein the luminaire provides polarized outputs. 
     
     
         7 . The luminaire of  claim 1  wherein the luminaire provides unpolarized outputs.