Multiview backlight, display, and method with reflective sub-elements having varying protrusion distances
A multiview backlight, multiview display, and method of multiview backlight operation include reflective multibeam elements configured to provide emitted light having directional light beams with directions corresponding to view directions of a multiview image. The multiview backlight includes a light guide configured to guide light and an array of the reflective multibeam elements. Each reflective multibeam element includes a plurality of reflective sub-elements and is configured to reflectively scatter out a portion of the guided light as the emitted light. The multiview display includes the multiview backlight and an array of light valves to modulate the directional light beams to provide the multiview image. Each reflective sub-element protrudes from a guiding surface of the light guide by a respective protrusion distance. At least some of the protrusion distances can vary as a function of distance along a length of the light guide.
1. A multiview backlight comprising:
a light guide configured to guide light along a length of the light guide as guided light; and
an array of reflective multibeam elements spaced apart from one another across the light guide on a guiding surface of the light guide, each reflective multibeam element of the reflective multibeam element array comprising reflective sub-elements and being configured to reflectively scatter out a portion of the guided light as emitted light comprising directional light beams having directions corresponding to respective view directions of a multiview display,
each reflective sub-element protruding from the guiding surface of the light guide by a respective protrusion distance, at least some of the protrusion distances varying as a function of a distance along the length of the light guide,
a reflective sub-element of the reflective sub-elements protruding from the guiding surface of the light guide and away from an interior of the light guide and comprising a material of the light guide.
2. The multiview backlight of claim 1 , wherein the protrusion distances increase in a first propagation direction along the length of the light guide.
3. The multiview backlight of claim 1 , wherein:
each reflective multibeam element of the reflective multibeam element array is configured to reflectively scatter respective emitted light that has a respective emitted light optical power level; and
the protrusion distances are selected such that the emitted light optical power levels are substantially equal for at least some of the reflective multibeam elements of the reflective multibeam element array.
4. The multiview backlight of claim 1 , wherein:
each reflective multibeam element of the reflective multibeam element array is configured to reflectively scatter respective emitted light that has a respective emitted light optical power level;
each reflective multibeam element of the reflective multibeam element array has a respective width in a direction parallel to the guiding surface of the light guide; and
the widths and the protrusion distances are selected such that the emitted light optical power levels are substantially equal for at least some of the reflective multibeam elements of the reflective multibeam element array.
5. The multi view backlight of claim 1 , wherein a size of each reflective multibeam element is between twenty-five percent and two hundred percent of a size of a light valve in an array of light valves of the multiview display.
6. The multiview backlight of claim 1 , wherein a reflective multibeam element of the reflective multibeam element array further comprises a reflective material adjacent to and coating reflective surfaces of the reflective sub-elements, an extent of the reflective material being confined to an extent of the reflective multibeam element to form a reflective island.
7. The multiview backlight of claim 1 , wherein the light guide is further configured to guide the guided light in a first propagation direction along the length of the light guide and a second propagation direction opposite the first propagation direction, the reflective sub-elements being further configured to reflectively scatter out a portion of the guided light having the second propagation direction as a portion of the emitted light comprising the directional light beams having the directions corresponding to the respective view directions of the multiview display.
8. The multi view backlight of claim 7 , wherein a cross-section of at least some of the reflective sub-elements, taken orthogonal to the guiding surface of the light guide and parallel to the first propagation direction, includes a first segment extending away from the guiding surface, a second segment extending from the first segment and substantially parallel to the guiding surface, and a third segment extending from the second segment to the guiding surface, the second segment being offset from the guiding surface by an offset value, the offset value increasing in the first propagation direction along the length of the light guide.
9. A multi view display comprising the multi view backlight of claim 1 , the multiview display further comprising an array of light valves configured to modulate the directional light beams to provide a multiview image having directional views corresponding to the view directions of the multiview display.
10. A multiview display comprising:
a light guide configured to guide light along a length of the light guide as guided light;
an array of reflective multibeam elements spaced apart from one another across the light guide on a guiding surface of the light guide, each reflective multibeam element of the reflective multibeam element array comprising a plurality of reflective sub-elements and being configured to reflectively scatter out a portion of the guided light as emitted light comprising directional light beams having directions corresponding to respective view directions of a multi view image; and
an array of light valves configured to modulate the directional light beams to provide the multiview image,
each reflective sub-element protruding from the guiding surface of the light guide by a respective protrusion distance, at least some of the protrusion distances varying as a function of distance along the length of the light guide,
a reflective sub-element of the reflective sub-elements protruding from the guiding surface of the light guide and away from an interior of the light guide and comprising a material of the light guide.
11. The multiview display of claim 10 , wherein one or both of a size of the reflective multibeam elements is between twenty-five percent and two hundred percent of a size of a light valve of the light valve array and the guided light is collimated according to a predetermined collimation factor, an emission pattern of the emitted light being a function of the predetermined collimation factor of the guided light.
12. The multiview display of claim 10 , wherein a reflective multibeam element of the reflective multibeam element array further comprises a reflective material adjacent to and coating reflective surfaces of the plurality of reflective sub-elements, the reflective material being confined within a boundary of the reflective multibeam element.
13. The multiview display of claim 10 , wherein:
each reflective multibeam element of the reflective multibeam element array is configured to reflectively scatter respective emitted light that has a respective emitted light optical power level; and
the protrusion distances are selected such that the emitted light optical power levels are substantially equal for at least some of the reflective multibeam elements of the reflective multibeam element array.
14. The multiview display of claim 10 , wherein:
each reflective multibeam element of the reflective multibeam element array is configured to reflectively scatter respective emitted light that has a respective emitted light optical power level;
each reflective multibeam element of the reflective multibeam element array has a respective width in a direction parallel to the guiding surface of the light guide; and
the widths and the protrusion distances are selected such that the emitted light optical power levels are substantially equal for at least some of the reflective multibeam elements of the reflective multibeam element array.
15. The multi view display of claim 10 , wherein:
the light valves of the light valve array are arranged in sets representing multiview pixels of the multiview display;
the light valves represent sub-pixels of the multiview pixels; and
the reflective multibeam elements of the reflective multibeam element array have a one-to-one correspondence to the multiview pixels of the multiview display.
16. A method of multiview backlight operation, the method comprising:
guiding light along a length of a light guide as guided light; and
reflecting a portion of the guided light out of the light guide using an array of reflective multibeam elements disposed on a guiding surface of the light guide to provide emitted light comprising directional light beams having different directions corresponding to respective different view directions of a multiview display,
a reflective multibeam element of the reflective multibeam element array comprising a plurality of reflective sub-elements,
each reflective sub-element protruding from the guiding surface of the light guide away from an interior of the light guide by a respective protrusion distance,
at least some of the protrusion distances varying as a function of distance along the length of the light guide,
each reflective sub-element comprising a material of the light guide.
17. The method of multiview backlight operation of claim 16 , wherein:
the guided light is collimated according to a predetermined collimation factor; and
an emission pattern of the emitted light is a function of the predetermined collimation factor of the guided light.