Reflective display system with enhanced color gamut

Abstract

A display system includes a reflective display panel and a light source tailored to enhance the color gamut of the system. The panel, which may be a Cholesteric liquid crystal display panel, includes an array of reflective pixels, each pixel comprising a first, second, and third subpixel of different first, second, and third colors. The light source illuminates a front of the display panel with source light to enable observers to view images formed by the panel. The light source includes a lamp and an enhancing element. The lamp, which may be a metal halide lamp, emits lamp light that includes the first, second, and third colors. The enhancing element may be an optical filter, a supplemental LED light source or other light source, or both. The enhancing element enhances the system color gamut, for example, by increasing the color gamut area relative to illumination with the lamp alone.

1 . A display system, comprising:
 a display panel having a front surface and a back surface, the display panel further including electronically addressable reflective pixels, each pixel comprising a first, second, and third subpixel of different first, second, and third colors, respectively,. the subpixels being separately electronically addressable; and   a light source configured to illuminate the front surface of the display panel with broadband source light, such that the broadband source light is selectively reflected by the pixels to provide a color image to an observer disposed in front of the display panel;   wherein the light source comprises a first lamp that emits a first broadband lamp light, the first broadband lamp light including light components of the first, second, and third colors;   wherein a combination of the first broadband lamp light and the display panel provide a first color gamut associated with reflection of the first broadband lamp light selectively from the first subpixel, and with reflection of the first broadband lamp light selectively from the second subpixel, and with reflection of the first broadband lamp light selectively from the third subpixel;   wherein a combination of the broadband source light and the display panel provide a second color gamut associated with reflection of the first broadband source light selectively from the first subpixel, and with reflection of the first broadband source light selectively from the second subpixel, and with reflection of the first broadband source light selectively from the third subpixel; and   wherein the light source includes a first enhancing element such that the second color gamut has an area greater than that of the first color gamut.   
     
     
         2 . The system of  claim 1 , wherein the first lamp comprises a metal halide lamp. 
     
     
         3 . The system of  claim 1 , wherein for each of the pixels, the first, second, and third subpixels have the same size as the pixel. 
     
     
         4 . The system of  claim 1 , wherein the display panel comprises a Cholesteric liquid crystal display (ChLCD) panel. 
     
     
         5 . The system of  claim 1 , wherein the area of the second color gamut is at least 10% greater than that of the first color gamut. 
     
     
         6 . The system of  claim 1 , wherein the area of the second color gamut is at least 20% greater than that of the first color gamut. 
     
     
         7 . The system of  claim 1 , wherein the area of the second color gamut is at least 30% greater than that of the first color gamut. 
     
     
         8 . The system of  claim 1 , wherein the first enhancing element comprises a first filter disposed to filter the first broadband lamp light. 
     
     
         9 . The system of  claim 8 , wherein the first filter comprises a multilayer optical interference filter. 
     
     
         10 . The system of  claim 8 , wherein the first filter comprises an absorptive filter. 
     
     
         11 . The system of  claim 8 , wherein the first filter selectively blocks light from 570 to 590 nm. 
     
     
         12 . The system of  claim 8 , wherein the light source further includes a second enhancing element, the second enhancing element comprising one or more light-emitting diode (LED). 
     
     
         13 . The system of  claim 12 , wherein the one or more LED emits visible light whose peak wavelength is greater than 600 nm. 
     
     
         14 . The system of  claim 13 , wherein the first filter transmits green and blue portions of the first broadband lamp light and blocks a red portion of the first broadband lamp light. 
     
     
         15 . The system of  claim 14 , wherein more of a red portion of the broadband source light is provided by the one or more LEDs than by the first lamp. 
     
     
         16 . The system of  claim 15 , wherein substantially all of the red portion of the broadband source light is provided by the one or more LEDs. 
     
     
         17 . The system of  claim 1 , wherein the first enhancing element comprises one or more light-emitting diode (LED). 
     
     
         18 . The system of  claim 17 , wherein the one or more LED emits visible light with a peak wavelength greater than 600 nm. 
     
     
         19 . The system of  claim 17 , wherein more of the broadband source light is provided by the first lamp than is provided by the one or more LED.