Compact Edge Illuminated Diffractive Display

Abstract

There is provided a projection display device comprising: a light source, an SBG device comprising a multiplicity of separately SBG elements sandwich between transparent substrate to which transparent electrodes have been applied. The substrates function as a light guide. A least one transparent electrode comprises plurality of independently switchable transparent electrodes elements, each electrode element substantially overlaying a unique SBG element. Each SBG element encodes image information to be projected on an image surface. Light coupled into the light guide, undergoes total internal reflection until diffracted out to the light guide by an activated SBG element. The SBG diffracts light out of the light guide to form an image region on an image surface when subjected to an applied voltage via said transparent electrodes.

What is claimed is: 
     
         1 . A projection display device comprising:
 a first light source emitting light of a first wavelength;   a first SBG device comprising a multiplicity of separately switchable SBG elements disposed in a single layer;   transparent substrates sandwiching said SBG device, said substrates together functioning as a first light guide;   transparent electrodes applied to opposing faces of said substrates, at least one of said transparent electrodes comprising a plurality of independently switchable transparent electrode elements, each of said independently switchable electrode elements substantially overlaying a unique SBG element;   a means for coupling said first wavelength light into said first light guide, said first wavelength light undergoing total internal reflection within said first light guide;   each said SBG element of said first SBG device diffracting said first wavelength light to form an image region on a image surface when subjected to an applied voltage via said transparent electrodes.   
     
     
         2 . The projection display of  claim 1  wherein the image surface is disposed in proximity to said display. 
     
     
         3 . The projection display of  claim 1  wherein the image surface is more than 25 centimeters from said display. 
     
     
         4 . The projection display of  claim 1  wherein the image surface is more than 50 centimeters from said display. 
     
     
         5 . The projection display of  claim 1  wherein one said image region comprises an image of a keyboard. 
     
     
         6 . The projection display of  claim 1  wherein said image region is an image pixel. 
     
     
         7 . The projection display of  claim 1  wherein said SBG elements pre-distort the shape of said image region. 
     
     
         8 . The projection display of  claim 1  wherein image surface is a diffusing material. 
     
     
         9 . The projection display of  claim 1  wherein image surface is the retina of an eye. 
     
     
         10 . The projection display of  claim 1  wherein said image surface is curved. 
     
     
         11 . The projection display of  claim 1  further comprising: at least one infrared source; means for directing infrared light from said source towards said image surface and at least one infrared sensor operative to detect light scatter from an object disposed in proximity to said image surface. 
     
     
         12 . The projection display of  claim 11  wherein said infrared source is a laser. 
     
     
         13 . The projection display of  claim 11  wherein said infrared sensor comprises an image sensing array and lens. 
     
     
         14 . The projection display of  claim 11  wherein said first SBG device contains at least one infrared diffracting SBG element operative to diffract infrared light from said infrared source towards said image surface when said infrared diffracting SBG element is subjected to an applied voltage via said transparent electrodes. 
     
     
         15 . The projection display of  claim 1  further comprising:
 second and third light sources emitting light of second and third wavelengths; 
 second and third SBG devices each comprising a multiplicity of separately switchable SBG elements disposed in a single layer; said SBG elements of said first, second and third SBG devices substantially overlapping; 
 transparent substrates sandwiching said second SBG device, said substrates together functioning as a second light guide; 
 transparent substrates sandwiching said third SBG device, said substrates together functioning as a third light guide; 
 transparent electrodes applied to substrate faces in contact with said second and third SBG devices, at least one of said transparent electrodes in contact with said second and third SBG devices comprising a plurality of independently switchable transparent electrodes elements, each of said independently switchable electrodes substantially overlaying a unique SBG element; 
 means for coupling said first, second and third wavelength light into said first, second and third light guides, said first, second and third wavelength light undergoing total internal reflection within said light guides, 
 each element of second SBG device diffracting said second wavelength light to form a second image region on an image surface when subjected to an applied voltage via said transparent electrodes, each element of third SBG device diffracting said third wavelength light to form a third image region on an image surface when subjected to an applied voltage via said transparent electrodes. 
 
     
     
         16 . The projection display of  claim 15  wherein said first, second and third image regions substantially overlap. 
     
     
         17 . The projection display of  claim 15  wherein in each said first, second and third wavelength SBG device said SBG elements are activated in bands, each said band comprising at least one row of SBG elements, each said band being continuously scrolled vertically, wherein at least one band in each of said first, second and third SBG devices is activated at any instant, wherein no overlap exists between said first, second and third wavelength SBG device bands.