Talbot pattern illuminator and display based thereon

Patent metadata

Field	Value
Publication number	US-11619774-B2
Application number	US-202117383245-A
Country	US
Kind code	B2
Filing date	Jul 22, 2021
Priority date	Jul 22, 2021
Publication date	Apr 4, 2023
Grant date	Apr 4, 2023

Abstract

An illuminator for a display panel includes a light source for providing a light beam and a lightguide coupled to the light source for receiving and propagating the light beam along the substrate. The lightguide includes an array of out-coupling gratings that runs parallel to the array of pixels for out-coupling portions of the light beam from the lightguide such that the out-coupled light beam portions propagate through the substrate and produce an array of optical power density peaks at the array of pixels due to Talbot effect. A period of the array of peaks is an integer multiple of a pitch of the array of pixels.

First claim

What is claimed is:

1. A display device comprising:
a display panel comprising an array of pixels on a substrate, and an illuminator for illuminating the display panel, the illuminator comprising a light source for providing a light beam, and a lightguide coupled to the light source for receiving and propagating the light beam along the substrate, the lightguide comprising a first array of out-coupling gratings;
wherein the first array runs parallel to the array of pixels for out-coupling portions of the light beam from the lightguide such that the out-coupled light beam portions propagate through the substrate and produce an array of optical power density peaks at the array of pixels due to Talbot effect, wherein a period of the array of optical power density peaks is M times p, where p is a pitch of the array of pixels, and M is an integer ≥1.

2. The display device of claim 1 , wherein a first pitch T 1 of the first array of out-coupling gratings is M times p, and wherein a distance D from a plane comprising the first array of out-coupling gratings to a plane comprising the array of pixels is D=K (T 1 ) 2 /(N λ), where K and N are integers ≥1 and λ is a wavelength of the light beam in the substrate.

3. The display device of claim 2 , wherein the first array of out-coupling gratings is disposed at a surface of the illuminator facing the substrate, wherein the distance D is equal to a thickness of the substrate.

4. The display device of claim 1 , wherein gratings of the first array of out-coupling gratings are configured to focus or defocus the out-coupled portions of the light beam.

5. The display device of claim 1 , wherein the lightguide comprises a first plate for propagating at least a portion of the light beam therein by a series of total internal reflections between opposed parallel surfaces of the first plate.

6. The display device of claim 5 , wherein the lightguide further comprises an array of redirecting gratings for redirecting portions of the light beam for spreading the light beam within the first plate.

7. The display device of claim 5 , wherein gratings of the first array of out-coupling gratings comprise volume hologram gratings.

8. The display device of claim 5 , wherein the lightguide further comprises a second plate for propagating at least a portion of the light beam therein by a series of total internal reflections between opposed parallel surfaces of the second plate, wherein the first and second plates are optically coupled together along their parallel surfaces.

9. The display device of claim 5 , further comprising a tiltable reflector in an optical path between the light source and the first plate, wherein the tiltable reflector is configured to couple the light beam into the first plate at an angle variable by tilting the tiltable reflector, whereby in operation, positions of the optical power density peaks at the array of pixels are adjustable relative to pixels of the array of pixels.

10. The display device of claim 9 , further comprising a controller operably coupled to the tiltable reflector for tilting the tiltable reflector to shift the array of optical power density peaks at the array of pixels by an integer multiple of the pitch p of the array of pixels.

11. The display device of claim 5 , wherein the light source is configured to provide first, second, and third light beam components at first, second, and third wavelengths respectively, the lightguide further comprising second and third arrays of out-coupling gratings optically coupled to the first plate, wherein the first, second, and third arrays of out-coupling gratings run parallel to the array of pixels at different distances therefrom for wavelength-selective out-coupling of portions of the first, second, and third light beam components respectively, for illuminating the array of pixels through the substrate.

12. The display device of claim 1 , wherein the lightguide comprises:
an optical dispatching circuit coupled to the light source for receiving and splitting the light beam into a plurality of sub-beams; and
a first array of linear waveguides coupled to the optical dispatching circuit for receiving the sub-beams from the optical dispatching circuit, wherein the linear waveguides run parallel to one another to propagate the sub-beams along the array of pixels, wherein the out-coupling gratings of the first array are optically coupled to linear waveguides of the first array of linear waveguides.

13. The display device of claim 12 , wherein:
the light source is configured to provide first, second, and third components of the light beam for carrying light at first, second, and third wavelengths respectively;
the optical dispatching circuit is configured for receiving and splitting each one of the first, second, and third light beam components into a plurality of sub-beams; and
the first array of linear waveguides is configured for receiving sub-beams of the first light beam component;
the lightguide further comprising:
second and third arrays of linear waveguides coupled to the optical dispatching circuit for receiving sub-beams of the second and third light beam components, respectively, from the optical dispatching circuit, wherein the linear waveguides of the second and third arrays are running parallel one another to propagate the sub-beams along the array of pixels; and
second and third arrays of out-coupling gratings optically coupled to the second and third arrays of linear waveguides, respectively, for out-coupling portions of the second and third light beam components, respectively, for illuminating the array of pixels through the substrate.

14. The display device of claim 13 , wherein the lightguide further comprises a color-selective reflector in an optical path between the first, second, and third arrays of out-coupling gratings and the substrate of the display panel, wherein the color-selective reflector is configured to provide different optical path lengths for the first, second, and third light beam components.

15. An illuminator comprising:
a light source for providing a light beam;
a plate for propagating at least a portion of the light beam therein by a series of total internal reflections between opposed parallel surfaces of the plate;
a tiltable reflector disposed in an optical path between the light source and plate and configured to couple the light beam into the plate at a variable in-coupling angle; and
a first array of out-coupling gratings optically coupled to the plate for out-coupling portions of the light beam at an out-coupling angle depending on the in-coupling angle such that the light beam portions form an array of optical power density peaks due to Talbot effect at a Talbot plane spaced apart from the plate, wherein positions of the peaks at the Talbot plane depend on the out-coupling angle of the light beam portions.

16. The illuminator of claim 15 , wherein the light source is configured to provide first, second, and third components of the light beam for carrying light at first, second, and third wavelengths respectively, the plate further comprising second and third arrays of out-coupling gratings optically coupled to the plate, wherein the first, second, and third arrays of out-coupling gratings run parallel to one another for wavelength-selective out-coupling of portions of the first, second, and third light beam components respectively, to form an array of optical power density peaks due to Talbot effect at the Talbot plane at the first, second, and third wavelengths, respectively, wherein positions of the optical power density peaks at the first, second, and t

Assignees

• Meta Platforms Tech Llc

Inventors

• Gollier Jacques
• Peng Fenglin
• Koshelev Alexander
• Calafiore Giuseppe
• Lu Lu
• Geng Ying
• Lee Yun-Han

Classifications

• G02B6/124

  Geodesic lenses or integrated gratings · CPC title

• G02B6/0036

  2-D arrangement of prisms, protrusions, indentations or roughened surfaces · CPC title

• G02B6/125

  Bends, branchings or intersections · CPC title

• G02B6/12004

  Combinations of two or more optical elements · CPC title

• G02B6/12007

  forming wavelength selective elements, e.g. multiplexer, demultiplexer · CPC title