Image display

Abstract

A display has a screen which incorporates a light modulator. The screen may be a front projection screen or a rear-projection screen. The screen is illuminated with light from a light source comprising an array of controllable light-emitters. The controllable-emitters and elements of the light modulator may be controlled to adjust the intensity of light emanating from corresponding areas on the screen. The display may provide a high dynamic range.

What is claimed is:  
     
       1. A display comprising:
 a first light modulation stage combining a light source and light modulation in the form of a plurality of independently-controllable pixels each arranged to emit light having an intensity that is variable, the first light-modulation stage operative to produce light modulated according to image data; 
 a second light-modulation stage in series with the first light-modulation stage; 
 an optical system comprising one or more mirrors and a diffuser in an optical path between the first and second light-modulation stages, the optical system configured to image the light modulated by the first light-modulation stage onto the second light modulation stage such that light from different pixels of the first light-modulation stage overlaps on the second light-modulation stage to provide light having a smooth variation in light intensity with position for further modulation by the second light-modulation stage; 
 a controller connected to control the pixels of the first light-modulation stage and controllable-elements of the second light-modulation stage to supply image features having a high spatial resolution. 
 
     
     
       2. A display according to  claim 1  wherein the display is 10 centimeters or less in thickness. 
     
     
       3. A display according to  claim 1  comprising a light guide arranged to capture light from the pixels of the first light-modulation stage. 
     
     
       4. A display according to  claim 1  wherein the first light modulation stage comprises a pass-through modulator. 
     
     
       5. A display according to  claim 4  wherein the first light modulation stage comprises an LCD panel. 
     
     
       6. A display according to  claim 1  wherein the first light modulation stage comprises a reflective modulator. 
     
     
       7. A display according to  claim 1  wherein the first light modulation stage comprises a DMD. 
     
     
       8. A display according to  claim 1  wherein the first light modulation stage comprises a plurality of separate light sources. 
     
     
       9. A display according to  claim 1  wherein the second light modulation stage comprises a retroreflective modulator. 
     
     
       10. A display according to  claim 1  wherein the second light modulation stage comprises a color light modulator. 
     
     
       11. A display according to  claim 10  wherein the second light modulation stage comprises an LCD panel. 
     
     
       12. A display according to  claim 1  wherein the controller is configured to estimate a light intensity at a controllable element of the second light-modulation stage by adding estimates of the light from a plurality of pixels of the first light-modulation stage that overlap at the controllable element. 
     
     
       13. A display according to  claim 12  wherein the controller is configured to control modulation performed by the controllable element in response to the estimated light intensity at the controllable element. 
     
     
       14. A display according to  claim 13  wherein the controller is configured to set the controllable element to transmit light in proportion to desired luminance value for the controllable element as specified by the image data divided by the estimated light intensity at the controllable element. 
     
     
       15. A display according to  claim 1  wherein the first and second light-modulation stages adjust luminance in steps that are not equal. 
     
     
       16. A display according to  claim 1  wherein the second light-modulation stage has a higher resolution than the first light modulation stage. 
     
     
       17. A display according to  claim 16  wherein the controller is configured to determine the intensity with which any pixel of the second light modulation stage will be illuminated for the way in which the pixels of the first light modulation stage are set by summing contributions from the pixels of the first light-modulation stage. 
     
     
       18. A display according to  claim 1  wherein the light emitted by each of the pixels of the first light modulation stage is distributed non-uniformly on the second light-modulation stage. 
     
     
       19. A display according to  claim 18  wherein the light emitted by each of the pixels of the first light modulation stage has a peaked distribution having an intensity that diminishes with distance away from a corresponding point on the second light-modulation stage. 
     
     
       20. A display according to  claim 19  wherein different ones of the pixels of the first light-modulation stage have different corresponding points on the second light-modulation stage that are spaced apart from one another. 
     
     
       21. A display according to  claim 19  wherein the light from a pixel of the first light-modulation stage illuminates more than 9 of the controllable elements of the second light-modulation stage.