Exit pupil expander

Patent metadata

Field	Value
Publication number	US-11892623-B2
Application number	US-201917041302-A
Country	US
Kind code	B2
Filing date	Feb 19, 2019
Priority date	Mar 28, 2018
Publication date	Feb 6, 2024
Grant date	Feb 6, 2024

Abstract

There is provided an exit pupil expander (EPE) for use in a diffractive display, the EPE comprising a plurality of diffractive zones on a waveguide and a plurality of non-diffractive zones between at least some of the diffractive zones.

First claim

The invention claimed is:

1. A diffractive display element for displaying an image, comprising:
a planar waveguide element,
an in-coupling region for diffractively coupling an image into the planar waveguide element,
an out-coupling region for diffractively coupling the image out of the planar waveguide element, and
an exit pupil expander (EPE) region in the planar waveguide element between the in-coupling region and out-coupling region for expanding the exit pupil of the image on the out-coupling region,
wherein:
the EPE region includes a plurality of diffractive zones arranged on a surface of the planar waveguide element and a plurality of non-diffractive zones between the diffractive zones, and
the EPE region includes at least ten different diffractive zones and at least ten different non-diffractive zones positioned such that at least one first non-diffractive zone is positioned between two diffractive zones in a first direction and at least one second non-diffractive zone is positioned between two diffractive zones in a second direction orthogonal to the first direction.

2. The element according to claim 1 , wherein the diffractive zones and non-diffractive zones are arranged as an irregular two-dimensional pattern.

3. The element according to claim 1 , wherein the diffractive zones and non-diffractive zones are arranged as a regular two-dimensional pattern.

4. The element according to claim 3 , further comprising at least two diffractive zones and/or at least two non-diffractive zones with different sizes or shapes.

5. The element according to claim 4 , wherein the diffractive zones comprise at least two grating zones with different grating properties.

6. The element according to claim 5 , wherein the diffractive zones and non-diffractive zones are dividable in a surface plane of the planar waveguide element into equally shaped unit zones.

7. The element according to claim 6 , wherein at least 20% of the total area of the EPE is formed of non-diffractive zones.

8. The element according to claim 7 , wherein the diffractive and non-diffractive zones are positioned such that it is possible to draw at least two different cross-sectional lines in along both main optical axes thereof so that the diffractive/non-diffractive profile along those lines is different.

9. The element according to claim 8 , wherein the diffractive zones and non-diffractive zones of the EPE region are configured so that at least a majority of light incoming from the in-coupling region is diffracted by at least one diffractive zone, bounced by total internal reflection in at least one non-diffractive zone, and again diffracted by at least one diffractive zone, typically different from the first diffractive zone, before exiting the EPE towards the out-coupling region.

10. The element according to claim 9 , wherein the non-diffractive zones of the EPE region are provided therein for increasing the brightness, uniformity or color balance of the display element, compared with a situation where the non-diffractive zones were replaced with diffractive zones.

11. The element according to claim 10 , wherein the EPE region has a width which is at least the same as the width of the out-coupling region.

12. A personal display device, such as a head-mounted display (HMD) or head-up display (HUD), comprising a diffractive display element according to claim 1 .

13. The element according to claim 1 , further comprising at least two diffractive zones and/or at least two non-diffractive zones with different sizes or shapes.

14. The element according to claim 1 , wherein the diffractive zones comprise at least two grating zones with different grating properties.

15. The element according to claim 1 , wherein the diffractive zones and non-diffractive zones are dividable in the surface plane of the waveguide into equally shaped unit zones.

16. The element according to claim 1 , wherein at least 20% of the total area of the EPE is formed of non-diffractive zones.

17. The element according to claim 1 , wherein the diffractive and non-diffractive zones are positioned such that it is possible to draw at least two different cross-sectional lines in along both main optical axes thereof so that the diffractive/non-diffractive profile along those lines is different.

18. The element according to claim 1 , wherein the diffractive zones and non-diffractive zones of the EPE region are configured so that at least a majority of light incoming from the in-coupling region is diffracted by at least one diffractive zone, bounced by total internal reflection in at least one non-diffractive zone, and again diffracted by at least one diffractive zone, typically different from the first diffractive zone, before exiting the EPE towards the out-coupling region.

19. The element according to claim 1 , wherein the non-diffractive zones of the EPE region are provided therein for increasing the brightness, uniformity or color balance of the display element, compared with a situation where the non-diffractive zones were replaced with diffractive zones.

20. The element according to claim 1 , wherein the EPE region has a width which is at least the same as the width of the out-coupling region.

Assignees

• Dispelix Oy

Inventors

• Olkkonen Juuso
• Myöhänen Petri

Classifications

• G02B27/0081 Primary

  with means for altering, e.g. enlarging, the entrance or exit pupil · CPC title

• G02B5/1814

  structurally combined with one or more further optical elements, e.g. lenses, mirrors, prisms or other diffraction gratings (G02B5/189 takes precedence) · CPC title

• G02B6/0016

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

• G02B6/124

  Geodesic lenses or integrated gratings · CPC title