Light illumination of displays with front light guide and coupling elements

Abstract

In various embodiments described herein, a display device includes a front illumination apparatus that comprises a first light guide disposed forward of an array of display elements, such as an array of interferometric modulators, to distribute light across the array of display elements. The light guide panel is edge illuminated by a light source positioned behind the array display elements. The light from such a light source is coupled to a second light guide disposed behind the array of display elements and positioned laterally with respect to the light source. The light in the second light guide is coupled into the first light guide using a small optical coupling element such as a turning mirror. In some embodiments the second light guide may comprise the backplate of the display device.

1 . A display device comprising:
 a reflective spatial light modulator;   a light source;   a light guide forward of the reflective spatial light modulator, the light guide having forward and rearward surfaces;   a light bar disposed forward or rearward of the light guide, the light bar configured to receive light from the light source and comprising a material through which light from the light source propagates; and   a turning mirror, the light bar including turning features configured to turn light propagating therein onto the turning mirror, the turning mirror disposed to direct light into the light guide, such that the light is total internally reflected from the forward and rearward surfaces of the light guide so as to be guided along the length of the light guide,   wherein the light guide is configured to direct the light coupled therein to the reflective spatial light modulator.   
     
     
         2 . The display device of  claim 1 , wherein the reflective spatial light modulator includes a microelectromechanical system (MEMS). 
     
     
         3 . The display device of  claim 1 , wherein the reflective spatial light modulator includes a plurality of interferometric modulators. 
     
     
         4 . The display device of  claim 1 , wherein the reflective spatial light modulator includes a substrate on which a plurality of modulating elements are formed. 
     
     
         5 . The display device of  claim 1 , wherein the light source includes a light emitting diode. 
     
     
         6 . The display device of  claim 1 , wherein the light bar is forward the light guide. 
     
     
         7 . The display device of  claim 1 , wherein the light bar is rearward the light guide. 
     
     
         8 . The display device of  claim 2 , wherein the light guide further includes a plurality of turning features in or on the light guide that direct the light propagating in the light guide onto the reflective spatial light modulator. 
     
     
         9 . The display device of  claim 8 , wherein the turning features include grooves. 
     
     
         10 . The display device of  claim 8 , wherein the turning features include diffractive features. 
     
     
         11 . The display device of  claim 4 , wherein the light guide includes the substrate on which the plurality of modulating elements are formed. 
     
     
         12 . The display device of  claim 1 , wherein the light guide includes a sheet, plate, film, film stack, or combination thereof. 
     
     
         13 . The display device of  claim 4 , further including an isolation layer between the light guide and the substrate. 
     
     
         14 . The display device of  claim 1 , further including turning features disposed on or in the light bar to turn the light propagating therein onto the optical coupler. 
     
     
         15 . The display device of  claim 1 , wherein the optical coupler includes a turning mirror. 
     
     
         16 . The display device of  claim 1 , wherein the turning mirror includes a curved reflective surface. 
     
     
         17 . The display device of  claim 16 , wherein the curved reflective surface is elliptical. 
     
     
         18 . The display device of  claim 17 , wherein the elliptical surface has foci proximal to ends of the light bar and the light guide. 
     
     
         19 . The display device of  claim 1 , wherein the turning mirror includes a plurality of planar mirror surfaces oriented at an angle with respect to each other. 
     
     
         20 . The display device of  claim 19 , wherein the angle is between about 90 and 120 degrees. 
     
     
         21 . The display device of  claim 19 , wherein the angle is about 90 degrees. 
     
     
         22 . The display device of  claim 19 , wherein the angle is about 120 degrees. 
     
     
         23 . The display device of  claim 1 , further including:
 a processor that is configured to communicate with the spatial light modulator, the processor being configured to process image data; and   a memory device that is configured to communicate with the processor.   
     
     
         24 . The display device of  claim 23 , further including a driver circuit configured to send at least one signal to the spatial light modulator. 
     
     
         25 . The display device of  claim 24 , further including a controller configured to send at least a portion of the image data to the driver circuit. 
     
     
         26 . The display device of  claim 25 , further including an image source module configured to send the image data to the processor. 
     
     
         27 . The display device of  claim 26 , wherein the image source module includes at least one of a receiver, transceiver, and transmitter. 
     
     
         28 . The display device of  claim 27 , further including an input device configured to receive input data and to communicate the input data to the processor. 
     
     
         29 . A display device comprising:
 a means for reflectively modulating light;   a means for illuminating;   a means for guiding light disposed forward of the reflectively light modulating means, the means for guiding light having forward and rearward surfaces;   a means for receiving light from the illuminating means, the light receiving means disposed forward or rearward of the light guiding means and including a material through which light from the illuminating means propagates; and   a turning mirror, the light receiving means including means for turning light configured to turn light propagating therein onto the turning mirror, the turning mirror disposed to direct light received from the light receiving means into the light guiding means, such that the light is total internally reflected from the forward and rearward surfaces of the means for guiding light so as to be guided along the length of the means for guiding light,   wherein the light guiding means is configured to direct the light coupled therein to the reflectively light modulating means.   
     
     
         30 . The display device of  claim 29 , wherein the reflectively light modulating means includes reflective spatial light modulator. 
     
     
         31 . The display device of  claim 30 , wherein the reflective spatial light modulator includes a microelectromechanical system (MEMS). 
     
     
         32 . The display device of  claim 29 , wherein the illuminating means includes a light emitting diode. 
     
     
         33 . The display device of  claim 29 , wherein the light receiving means includes a light bar. 
     
     
         34 . The display of  claim 29 , wherein the light guiding means includes a light guide. 
     
     
         35 . The display device of  claim 29 , wherein the light guiding means further includes means for turning light. 
     
     
         36 . The display device of  claim 35 , wherein the light turning means includes grooves. 
     
     
         37 . The display device of  claim 35 , wherein the light turning means includes diffractive features. 
     
     
         38 . The display device of  claim 29 , wherein the light coupling means includes a turning mirror. 
     
     
         39 . The display device of  claim 29 , further including a means for supporting the reflectively light modulating means. 
     
     
         40 . The display device of  claim 39 , further including a means for isolation disposed between the supporting means and the light guiding means. 
     
     
         41 . The display device of  claim 39 , wherein the supporting means includes a substrate. 
     
     
         42 . A method of manufacturing a display device, the method comprising:
 providing a reflective spatial light modulator;   providing a light source;   disposing a light guide forward of the reflective spatial light modulator, the light guide having forward and rearward surfaces;   disposing a light bar forward or rearward of the light guide, the light bar configured to receive light from the light and including a material through which light from the light source propagates;   providing a plurality of turning features on the light bar; and   providing a turning mirror, the turning features on the light bar configured to direct light towards the turning mirror, the turning mirror configured to direct light received from the light bar into the light guide, such that the light is total internally reflected from the forward and rearward surfaces of the light guide so as to be guided along the length of the light guide.   
     
     
         43 . The method of  claim 42 , further includes forming a plurality of turning features on the light guide.