Multibeam element-based backlighting having converging views
A multiview backlight and a multiview display employ multibeam elements configured to provide a tilted plurality of light beams having different principal angular directions corresponding to different view directions of a plurality of views of the multiview display. Further, the tilted plurality of light beams has a tilt toward a center of a view zone of the multiview display to provide converging views. The multiview backlight includes a light guide and an array of the multibeam elements. The multiview display further includes multiview pixels that include view pixels to modulate the tilted plurality of light beams having the tilt and the different principal angular directions.
1. A multiview backlight comprising:
a light guide configured to guide light; and
an array of multibeam elements spaced apart from one another along a length of the light guide, each multibeam element of the array being configured to couple out from the light guide a portion of the guided light as a tilted plurality of light beams having different principal angular directions corresponding to respective different view directions of a plurality of views of a multiview display,
wherein the tilted plurality of light beams has a tilt toward a center of a view zone of the multiview display to provide converging views, a central axis of tilted plurality of light beams being configured by the tilt to intersect the view zone center.
2. The multiview backlight of claim 1 , wherein a lateral offset of a multibeam element of the multibeam element array relative to a location of a corresponding multiview pixel of the multiview display is configured to provide the tilt of the tilted plurality of light beams toward the view zone center, the offset being provided by an inter-element distance between a pair of multibeam elements of the multibeam element array that is greater than an inter-pixel distance between a corresponding pair of multiview pixels of the multiview display.
3. The multiview backlight of claim 2 , wherein each of the multibeam elements of the multibeam element array has a corresponding scattering characteristic configured to further tilt the tilted plurality of light beams towards the view zone center, the corresponding scattering characteristic of the multibeam elements varying as a function of location of each of a multibeam element within the array along the light guide length.
4. The multiview backlight of claim 1 , wherein different views of the plurality of views of the multiview display have respective view locations within the view zone, a light beam of the tilted plurality of light beams corresponding to each of the different views being configured by the tilt to intersect the view zone at the respective view locations to provide the converging views.
5. The multiview backlight of claim 1 , wherein a size of the multibeam element comparable to size of view pixel of the multiview display, the multibeam element being between fifty percent and two hundred percent of the view pixel size.
6. The multiview backlight of claim 1 , wherein the multibeam element comprises a diffraction grating configured to diffractively couple out the portion of the guided light as the tilted plurality of light beams.
7. The multiview backlight of claim 1 , wherein the multibeam element comprises one or both of a micro-reflective element and a micro-refractive element, the micro-reflective element being configured to reflectively couple out a portion of the guided light, the micro-refractive element being configured to refractively couple out a portion of the guided light.
8. The multiview backlight of claim 1 , further comprising a light source optically coupled to an input of the light guide, the light source being configured to provide the guided light, the guided light one or both of having a non-zero propagation angle and being collimated according to a predetermined collimation factor.
9. A multiview display comprising the multiview backlight of claim 1 , the multiview display further comprising an array of light valves configured to modulate light beams of the tilted plurality of light beams, a light valve of the array corresponding to a view pixel and a set of light valves of the light valve array corresponding to a multiview pixel of the multiview display.
10. A method of multiview backlight operation, the method comprising:
guiding light in a propagation direction along a length of a light guide; and
coupling a portion of the guided light out of the light guide using a multibeam element to provide a tilted plurality of light beams having different principal angular directions corresponding to respective different view directions of a multiview display,
wherein the tilted plurality of light beams has a tilt toward a center of a view zone of the multiview display to provide converging views, a central axis of tilted plurality of light beams being configured by the tilt to intersect the view zone center.
11. The method of multiview backlight operation of claim 10 , wherein a size of the multibeam element is comparable to a size of a sub-pixel in a multiview pixel of the multiview display.
12. The method of multiview backlight operation of claim 10 , further comprising providing the tilt of the tilted plurality of light beams either by selecting an inter-element distance between a pair of multibeam elements that is greater than an inter-pixel distance between a corresponding pair of multiview pixels of the multiview display or by both selecting the greater inter-element distance and varying a scattering characteristic of multibeam elements in an array of multibeam elements arranged along the light guide length as a function of location of the multibeam element within the multibeam element array.
13. The method of multiview backlight operation of claim 10 , further comprising modulating the light beams of the tilted plurality of light beams using a plurality of light valves configured as a multiview pixel of the multiview display.