Dual light guide grating-based backlight and electronic display using same

Patent metadata

Field	Value
Publication number	US-2018024289-A1
Application number	US-201715724209-A
Country	US
Kind code	A1
Filing date	Oct 3, 2017
Priority date	Apr 23, 2015
Publication date	Jan 25, 2018
Grant date	—

Abstract

Dual light guide, grating-based backlighting redirects light guided in a first light guide in a first direction into a second light guide in a second direction of a grating-based backlight. A dual light guide, grating-based backlight includes the first light guide, the second light guide and a redirection coupler configured to redirect the guided light beam from the first light guide into the second light guide in the second direction. The dual light guide, grating-based backlight further includes a diffraction grating configured to diffractively couple out a portion of the redirected light beam from the second light guide as a coupled-out light beam directed away from a surface of the second light guide at a predetermined principal angular direction.

First claim

What is claimed is:

1 . A dual light guide, grating-based backlight comprising:
a first plate light guide configured to guide a light beam in a first direction and at a non-zero propagation angle; a second plate light guide configured to receive and guide a redirected light beam in a second direction; a redirection coupler configured to redirect the guided light beam of the first plate light guide into the second plate light guide as the redirected light beam in the second direction; and a diffraction grating configured to diffractively couple out a portion of the redirected light beam from the second plate light guide as a coupled-out light beam directed away from a surface of the second plate light guide at predetermined principal angular direction.

2 . The dual light guide, grating-based backlight of claim 1 , wherein the guided light beam is collimated in a plane perpendicular to a plane of the first plate light guide.

3 . The dual light guide, grating-based backlight of claim 1 , wherein the first plate light guide and the second plate light guide are substantially parallel to one another, and wherein the first direction of the guided light beam is substantially opposite to the second direction of the redirected light beam.

4 . The dual light guide, grating-based backlight of claim 1 , wherein the redirection coupler comprises a corner reflector at an output end of the first plate light guide and at an input end of the second plate light guide.

5 . The dual light guide, grating-based backlight of claim 1 , wherein the redirection coupler comprises a tilted mirror and a grating coupler, the tilted mirror being configured to reflect the guided light beam received from the first plate light guide toward the grating coupler, the grating coupler being configured to diffract the reflected light beam from the tilted mirror into the second direction as the redirected light beam to be guided in the second plate light guide.

6 . The dual light guide, grating-based backlight of claim 5 , wherein the redirection coupler further comprises a second mirror configured to reflect and redirect light of a secondary diffraction product from the grating coupler into the second direction to augment the redirected light beam within the second plate light guide.

7 . The dual light guide, grating-based backlight of claim 5 , wherein the tilted mirror is configured to reflect the guided light beam from the first plate light guide toward the grating coupler to provide a substantially normal angle of incidence of the reflected light beam at the grating coupler.

8 . The dual light guide, grating-based backlight of claim 5 , wherein the grating coupler comprises a reflective diffraction grating.

9 . The dual light guide, grating-based backlight of claim 1 , wherein the redirection coupler comprises a collimating mirror.

10 . The dual light guide, grating-based backlight of claim 1 , wherein the diffraction grating comprises a multibeam diffraction grating configured to couple out the portion of the redirected light beam as a plurality of coupled-out light beams, a light beam of the coupled-out light beam plurality having a different principal angular direction from other light beams of the coupled-out light beam plurality.

11 . The dual light guide, grating-based backlight of claim 10 , wherein the multibeam diffraction grating is a linearly chirped diffraction grating.

12 . The dual light guide, grating-based backlight of claim 10 , wherein the plurality of coupled-out light beams having different principal angular directions form a light field configured to provide pixels corresponding to different views of a three dimensional (3D) electronic display.

13 . The dual light guide, grating-based backlight of claim 1 , further comprising a light source coupled to an input end of the first plate light guide opposite an output end adjacent to the redirection coupler, the light source to provide a plurality of different colors of light to be guided as a plurality of different color light beams.

14 . The dual light guide, grating-based backlight of claim 13 , wherein the different color light beams are guided within the first plate light guide at different, color-specific, non-zero propagation angles.

15 . The dual light guide, grating-based backlight of claim 13 , wherein the redirection coupler comprises a grating coupler configured to redirect the different color light beams in the second direction, each of the different color light beams being redirected at a different, color-specific, non-zero propagation angle into the second plate light guide by the grating coupler.

16 . An electronic display comprising the dual light guide, grating-based backlight of claim 1 , the electronic display further comprising a light valve configured to modulate the coupled-out light beam, the diffraction grating being at the surface of the second plate light guide that is adjacent to the light valve, wherein the modulated, coupled-out light beam corresponds to a pixel of the electronic display.

17 . A three-dimensional (3D) electronic display comprising:
a first light guide and a second light guide; a redirection coupler configured to couple and redirect a guided light beam from the first light guide into the second light guide; an array of multibeam diffraction gratings at a surface of the second light guide, a multibeam diffraction grating of the array being configured to diffractively couple out a portion of the redirected light beam guided within the second light guide as plurality of coupled-out light beams having different principal angular directions representing different views of the 3D electronic display; and a light valve array configured to modulate the coupled-out light beams, the modulated coupled-out light beams representing pixels corresponding to the different views.

18 . The 3D electronic display of claim 17 , wherein one or both of the first light guide and the second light guide comprise a plate light guide, the first and second light guides being arranged substantially co-planar to one another, and wherein the first and second light guides are configured to guide light as a collimated light beam at a non-zero propagation angle.

19 . The 3D electronic display of claim 17 , wherein the redirection coupler comprises a tilted mirror and a reflective grating coupler, the tilted mirror being configured to reflect the guided light beam from the first light guide toward the reflective grating coupler, the reflective grating coupler being configured to diffract the reflected guided light beam from the tilted mirror into the second light guide as a redirected guided light beam within the second light guide.

20 . The 3D electronic display of claim 17 , wherein the multibeam diffraction grating is a chirped diffraction grating comprising one of curved grooves and curved ridges that are spaced apart from one another.

21 . The 3D electronic display of claim 17 , further comprising a light source optically coupled to an input end of the first light guide opposite an output end of the first light guide adjacent to the redirection coupler, the light source comprising a plurality of optical emitters arranged along the input end of the first light guide to provide a corresponding plurality of light beams guided in substantially parallel bands by the first light guide.

22 . The 3D electronic display of claim 21 , wherein an optical length of the first light guide in a propagation directio

Assignees

• Leia Inc

Inventors

• Fattal David A

Classifications

• G02B6/0031

  Reflecting element, sheet or layer · CPC title

• G02B6/0076 Primary

  Stacked arrangements of multiple light guides of the same or different cross-sectional area · CPC title

• G02B6/0038

  Linear indentations or grooves, e.g. arc-shaped grooves or meandering grooves, extending over the full length or width of the light guide · CPC title

• G02B6/0028

  Light guide, e.g. taper · CPC title

• G02B6/0016

  Grooves, prisms, gratings, scattering particles or rough surfaces · CPC title