Lighting adjustment for head mounted display

Abstract

An apparatus includes a light source, a display array, a light relay, a photodetector, and control circuitry. The light source is for providing lamp light during an ON-time of the light source. The display array is positioned to receive and selectively manipulate the lamp light. The light relay is positioned to receive the image light from the display array. Control circuitry is coupled to the light source for adjusting the light source and coupled to receive an output of the photodetector.

What is claimed is: 
     
         1 . An apparatus for a head mounted display (“HMD”), the apparatus comprising:
 a light source including a first, second, and third light emitting element for sequentially providing, respectively, first, second, and third color lamp light; 
 a display array positioned to receive and selectively manipulate the first, second, and third color lamp light to generate a color sequential image; 
 a light relay positioned to receive the color sequential image from the display array and to deliver the color sequential image to a viewing end of the light relay for presenting to an eye of a user when the HMD is worn; 
 a photodetector optically coupled to receive ambient light from the light relay and optically coupled to receive the first, second, and third color lamp light; and 
 control circuitry coupled to receive an output of the photodetector and coupled to the light source for sequentially cycling the first, second, and third light emitting elements based on the output of the photodetector. 
 
     
     
         2 . The apparatus of  claim 1  further comprising a beam splitter disposed at the viewing end of the light relay for directing the ambient light into the light relay, wherein the ambient light is from an external scene-side of the light relay. 
     
     
         3 . The apparatus of  claim 1  further comprising an end reflector, wherein a display module includes the display array, the light source, and a polarizing beam splitter and the end reflector is disposed at an opposite end of an eyepiece from the display module, and wherein the end reflector is positioned to reflect the color sequential image, which is received from the display array via the light relay. 
     
     
         4 . The apparatus of  claim 3 , wherein the end reflector includes a hole and the photodetector is optically coupled to receive the ambient light and the first, second, and third color lamp light through the hole. 
     
     
         5 . The apparatus of  claim 1 , wherein the display array is a color sequential Liquid Crystal on Silicon (“LCOS”) array, and wherein the first, second, and third light emitting elements are a red, green, and blue light emitting diode (“LED”), respectively. 
     
     
         6 . The apparatus of  claim 1  further comprising a polarizing beam splitter disposed on a display side of the light relay, wherein the polarizing beam splitter is positioned to direct the first, second, and third lamp light to the display array. 
     
     
         7 . The apparatus of  claim 1 , wherein the photodetector is optically coupled to receive the first, second, and third color lamp light from the light relay. 
     
     
         8 . An apparatus for a head mounted display (“HMD”), the apparatus comprising:
 a light source for providing lamp light during an ON-time of the light source; 
 a display array positioned to receive and selectively manipulate the lamp light to generate computer generated image (“CGI”) light; 
 a light relay positioned to receive the CGI light from the display array and deliver the CGI light to a viewing end of the light relay for presenting to an eye of a user; 
 a photodetector optically coupled to receive ambient light from the light relay; and 
 control circuitry coupled to receive an output signal of the photodetector and coupled to the light source for adjusting the ON-time of the light source based on the output signal of the photodetector. 
 
     
     
         9 . The apparatus of  claim 8 , further comprising a beam splitter disposed at the viewing end of the light relay and positioned for directing the CGI light in an eyeward direction and directing the ambient light into the light relay. 
     
     
         10 . The apparatus of  claim 9 , wherein the beam splitter directs the ambient light from an external scene side of the HMD that is opposite an eyeward side of the HMD. 
     
     
         11 . The apparatus of  claim 8 , wherein the photodetector is optically coupled to receive the ambient light from the light relay that is traveling in a substantially opposite direction as the CGI light immediately leaving the display array. 
     
     
         12 . The apparatus of  claim 8  further comprising an end reflector, wherein a display module includes the display array, the light source, and a polarizing beam splitter and the end reflector is disposed at an opposite end of an eyepiece from the display module,
 wherein the end reflector includes a hole and the photodetector is optically coupled to receive the ambient light through the hole.