Pixel-shifting projection lens assembly to provide optical interlacing for increased addressability

Abstract

A projection display system includes a projection lens assembly that has multiple projection lens elements that are configured to receive light imparted with display information by a pixelated display device. The projection lens elements project the light toward a display screen. A pixel-shifting element is included within the projection lens assembly to cyclically shift between at least two positions within the projection lens assembly to form at a display screen at least two interlaced arrays of pixels. An electromechanical transducer is coupled to the pixel-shifting element to impart on it the cyclic shifting between positions.

1 . A projection display system, comprising: 
 a pixelated display device;    an illumination system that directs illumination light to the pixelated display device for display information to be imparted on the light; and    a projection lens assembly that receives the light with imparted display information from the pixelated display device and projects the light, the projection lens assembly including a pixel-shifting element that shifts between at least two positions within the projections lens assembly to form at least two interlaced arrays of pixels, the pixel-shifting element including a fold mirror.    
   
   
       2 . The projection display system of  claim 1  in which the shifting of the pixel-shifting element includes cyclic tilting of the fold mirror.  
   
   
       3 . The projection display system of  claim 1  further comprising a display screen, wherein the projection lens assembly projects the light toward the display screen to form the interlaced arrays of pixels at the display screen.  
   
   
       4 . The projection display system of  claim 1  in which the projection lens assembly further includes a lens positioned along a path of the light after the pixel-shifting element.  
   
   
       5 . The projection display system of  claim 1  in which the projection lens assembly further includes a lens positioned along a path of the light before the pixel-shifting element.  
   
   
       6 . The projection display system of  claim 1  in which the fold mirror is positioned within the projection lens assembly.  
   
   
       7 . The projection display system of  claim 1  in which the pixilated display device is a digital micromirror device (DMD).  
   
   
       8 . The projection display system of  claim 1  in which the pixel-shifting element cyclically shifts between two positions that provide a vertical offset between two arrays of pixels.  
   
   
       9 . The projection display system of  claim 1  in which the pixel-shifting element cyclically shifts between four positions to form at the display screen four interlaced arrays of pixels.  
   
   
       10 . The projection display system of  claim 1  in which the display device is operated in a field-sequential manner with red, green, and blue color sub-fields and the pixel-shifting element cyclically shifts between the at least two positions during blue color sub-fields.  
   
   
       11 . The projection display system of  claim 1  in which the pixel-shifting element includes a lens element that has at least one curved surface and is positioned within the projection lens assembly and in which the cyclic shifting of the pixel-shifting element includes cyclic translation of the lens element.  
   
   
       12 . The projection display system of  claim 1  in which the pixel-shifting element is cyclically shifted by an electromechanical transducer.  
   
   
       13 . A projection lens assembly for a projection display system, comprising: 
 multiple projection lens elements; and    a pixel-shifting element positioned between projection lens elements of the projection lens assembly and that cyclically shifts between at least two positions within the projection lens assembly.    
   
   
       14 . The projection lens assembly of  claim 13  in which the pixel-shifting element cyclically shifts between two vertically offset positions.  
   
   
       15 . The projection lens assembly of  claim 13  in which the pixel-shifting element cyclically shifts between four positions.  
   
   
       16 . The projection lens assembly of  claim 13  in which the pixel-shifting element includes a configurable wedge positioned within the projection lens assembly and in which the cyclic shifting of the pixel-shifting element includes tilting of the wedge into first and second configurations.  
   
   
       17 . The projection lens assembly of  claim 16  in which the wedge includes a transparent wedge positioned within the projection lens assembly and in which the cyclic shifting of the pixel-shifting element includes rotation about an axis extending through the wedge.  
   
   
       18 . The projection lens assembly of  claim 13  in which the pixel-shifting element includes a fold mirror.  
   
   
       19 . A liquid-crystal display projector configured to display a color image, the projector comprising: 
 a light source;    a color separation optical system for separating a light from the light source into red, green, and blue color beams;    a first, a second, and a third liquid-crystal display elements arranged to transmit the red, green, and blue color beams, respectively;    a color mixing optical system for mixing the color beams, transmitted through the liquid-crystal display elements, into one beam;    a projection lens assembly that receives the beam from the color mixing optical system and projects the beam toward a display screen, the projection lens assembly including a pixel-shifting element that shifts between at least two positions within the projections lens assembly to form interlaced arrays of pixels.    
   
   
       20 . The liquid-crystal display projector of  claim 19 , wherein the pixel-shifting element includes a fold mirror positioned within the projection lens assembly.  
   
   
       21 . The projection display system of  claim 20  in which the shifting of the pixel-shifting element includes cyclic tilting of the fold mirror.  
   
   
       22 . The projection display system of  claim 19  in which the projection lens assembly further including a lens positioned along a path of the light after the pixel-shifting element.  
   
   
       23 . The projection display system of  claim 19  in which the projection lens assembly further including a lens positioned along a path of the light before the pixel-shifting element.