Time-multiplexed backlight, multiview display, and method

Abstract

A time-multiplexed backlight and display employ a broad-angle backlight to provide broad-angle emitted light corresponding to a 2D portion of a displayed image, a multiview backlight to provide directional emitted light corresponding to a multiview portion of the displayed image, and a mode controller configured to time-multiplex the 2D portion and the multiview portion by activating the broad-angle backlight and the multiview backlight in sequential manner as a composite image.

What is claimed is: 
     
         1 . A time-multiplexed backlight comprising:
 a broad-angle backlight configured to provide broad-angle emitted light from an emission surface during a two-dimensional (2D) mode;   a multiview backlight comprising an array of multibeam elements, each multibeam element of the multibeam element array being configured to provide a plurality of directional light beams having directions corresponding to different view directions of a multiview image during a multiview mode; and   a mode controller configured to time-multiplex the 2D and multiview modes by sequentially activating the broad-angle backlight during a first time interval and the multiview backlight during a second time interval,   wherein the multiview backlight is disposed adjacent to the emission surface of the broad-angle backlight and is transparent to the broad-angle emitted light during the 2D mode.   
     
     
         2 . The time-multiplexed backlight of  claim 1 , wherein the multiview backlight further comprises:
 a light guide configured to guide light as guided light; and   wherein the array of multibeam elements are spaced apart from one another across the light guide, each multibeam element of the multibeam element array being configured to scatter out a portion of the guided light from the light guide as the plurality of directional light beams.   
     
     
         3 . The time-multiplexed backlight of  claim 2 , wherein the light guide is configured to guide the guided light according to a predetermined collimation factor as collimated guided light. 
     
     
         4 . The time-multiplexed backlight of  claim 2 , wherein multibeam elements of the multibeam element array comprise one or more of a diffraction grating configured to diffractively scatter out the guided light, a micro-reflective element configured to reflectively scatter out the guided light, and a micro-refractive element configured to refractively scatter out the guided light. 
     
     
         5 . The time-multiplexed backlight of  claim 4 , wherein the diffraction grating of a multibeam element of the multibeam element array comprises a plurality of individual sub-gratings. 
     
     
         6 . The time-multiplexed backlight of  claim 1 , wherein the mode controller is configured to switch between the 2D mode and the multiview mode by sequentially activating a light source of the broad-angle backlight to provide the broad-angle emitted light during the 2D mode and a light source of the multiview backlight to provide the plurality of directional light beams during the multiview mode. 
     
     
         7 . A time-multiplexed multiview display comprising the time-multiplexed backlight of  claim 1 , the time-multiplexed multiview display further comprising:
 an array of light valves configured to modulate the broad-angle emitted light during the 2D mode to provide a 2D image and to modulate the plurality of directional light beams during the multiview mode to provide the multiview image.   
     
     
         8 . The time-multiplexed multiview display of  claim 7 , wherein the mode controller is configured to sequentially activate the broad-angle backlight during the first time interval to provide the 2D image and the multiview backlight during the second time interval to provide the multiview image, the 2D image and the multiview image being superimposed with each other on the time-multiplexed multiview display to provide a composite image. 
     
     
         9 . The time-multiplexed multiview display of  claim 7 , wherein a size of each multibeam element of the multibeam element array is between one quarter and two times a size of a light valve of the light valve array. 
     
     
         10 . A time-multiplexed multiview display comprising:
 a broad-angle backlight configured to provide broad-angle emitted light;   a multiview backlight comprising an array of multibeam elements, each multibeam element being configured to provide directional light beams having directions corresponding to different view directions of a multiview image;   an array of light valves configured to modulate the broad-angle emitted light to provide a 2D image and to modulate the directional light beams to provide the multiview image; and   a mode controller configured to sequentially activate the broad-angle backlight and the multiview backlight, the 2D image and multiview image being superimposed on the time-multiplexed multiview display as a composite image.   
     
     
         11 . The time-multiplexed multiview display of  claim 10 , wherein the multiview backlight further comprises:
 a light guide configured to guide light as guided light; and   wherein the array of multibeam elements are spaced apart from one another across the light guide, each multibeam element of the multibeam element array being configured to scatter out a portion of the guided light from the light guide as the directional light beams.   
     
     
         12 . The time-multiplexed multiview display of  claim 11 , wherein the light guide is configured to guide the guided light according to a collimation factor as collimated guided light, and wherein a size of each multibeam element of the multibeam element array is between one quarter and two times a size of a light valve of the light valve array. 
     
     
         13 . The time-multiplexed multiview display of  claim 11 , wherein each multibeam element of the multibeam element array comprises one or more of a diffraction grating configured to diffractively scatter out the guided light, a micro-reflective element configured to reflectively scatter out the guided light, and a micro-refractive element configured to refractively scatter out the guided light. 
     
     
         14 . The time-multiplexed multiview display of  claim 11 , wherein the mode controller is configured to activate a light source of the broad-angle backlight to provide the broad-angle emitted light and to activate a light source of the multiview backlight to provide directional light beams to sequentially activate the broad-angle backlight and the multiview backlight. 
     
     
         15 . The time-multiplexed multiview display of  claim 10 , wherein the multiview backlight is disposed between the broad-angle backlight and the light valve array, the multiview backlight being transparent to the broad-angle emitted light. 
     
     
         16 . A method of operating a time-multiplexed backlight, the method comprising:
 providing broad-angle emitted light during a 2D mode using a broad-angle backlight;   providing directional emitted light during a multiview mode using a multiview backlight having an array of multibeam elements, the directional emitted light comprising a plurality of directional light beams provided by each multibeam element of the multibeam element array; and   time multiplexing the 2D and multiview modes using a mode controller to sequentially activate the broad-angle backlight during a first sequential time interval corresponding to the 2D mode and the multiview backlight during a second sequential time interval corresponding to the multiview mode,   wherein directions of the plurality of directional light beams correspond to different view directions of a multiview image.   
     
     
         17 . The method of operating a time-multiplexed backlight of  claim 16 , wherein providing directional emitted light comprises:
 guiding light in a light guide as guided light; and   scattering out a portion of the guided light as the directional emitted light using multibeam elements of the multibeam element array, each multibeam element of the multibeam element array comprising one or more of a diffraction grating, a micro-refractive element, and a micro-reflective element.   
     
     
         18 . The method of operating a time-multiplexed backlight of  claim 17 , further comprising providing light to the light guide, the guided light within the light guide being collimated according to a predetermined collimation factor. 
     
     
         19 . The method of operating a time-multiplexed backlight of  claim 16 , further comprising:
 modulating the broad-angle emitted light using an array of light valves to provide a 2D image during the 2D mode; and   modulating the plurality of directional light beams of the directional emitted light using the light valve array to provide a multiview image during the multiview mode,   wherein time-multiplexing the 2D mode and the multiview mode superimposes the 2D image and multiview images to provide a composite image comprising both 2D content and multiview content.   
     
     
         20 . The method of operating a time-multiplexed backlight of  claim 19 , wherein a size of a multibeam element of the multibeam element array is between one quarter and two times a size of a light valve of the light valve array.