Display device for enlarging the field of view

Patent metadata

Field	Value
Publication number	US-11340457-B2
Application number	US-201816630648-A
Country	US
Kind code	B2
Filing date	Jul 12, 2018
Priority date	Jul 13, 2017
Publication date	May 24, 2022
Grant date	May 24, 2022

Abstract

A display device for representing two-dimensional and/or three-dimensional objects or scenes, having at least one spatial light modulation device having pixels for modulating light, at least one optical system, and at least one light guiding device. Light beams originating from the individual pixels of the spatial light modulation device are incident on the at least one light guiding device at different angles on average in relation to the surface of the at least one light guiding device and can be coupled therein, whereby a coupling angular spectrum is definable. The light beams propagating in the at least one light guiding device can be coupled out of the at least one light guiding device at different angles on average in relation to an observer region, whereby a decoupling angular spectrum is definable. The decoupling angular spectrum is enlarged in comparison to the coupling angular spectrum.

First claim

The invention claimed is:

1. A display device for representing two-dimensional and/or three-dimensional objects or scenes, comprising
at least one spatial light modulation device having pixels for modulating light,
at least one optical system,
at least one light guiding device,
where the optical system is designed in such a way that light beams originating from the individual pixels of the spatial light modulation device are incident on the at least one light guiding device at different angles on average in relation to the surface of the at least one light guiding device and can be coupled therein, whereby a coupling angular spectrum is definable, where the light beams propagating in the at least one light guiding device can be coupled out of the at least one light guiding device at different angles on average in relation to an observer region, whereby a decoupling angular spectrum is definable, where the decoupling angular spectrum is enlarged in comparison to the coupling angular spectrum.

2. The display device as claimed in claim 1 , wherein the at least one light guiding device comprises a light guide, at least one light coupling device, and at least one light decoupling device, where the light propagates within the light guide via a reflection at boundary surfaces of the light guide, and where the coupling of the light out of the light guide by means of the light decoupling device is provided after a defined number of reflections of the light at the boundary surfaces of the light guide.

3. The display device as claimed in claim 2 , wherein a controllable element is provided for varying the defined number of reflections of the light at the boundary surfaces of the light guide.

4. The display device as claimed in claim 1 , wherein if the light incident on the at least one light guiding device is formed as a light bundle or light field, which comprises multiple or a plurality of light beams, a coupling out of the light guide is provided for the light beams after a number of reflections at the boundary surfaces of the light guide of the light guiding device which is equal in each case for all light beams of the light bundle or light field.

5. The display device as claimed in claim 1 , wherein in each case a light incidence position on one of the boundary surfaces of the light guide, which the light from this pixel reaches after a defined number of reflections, is determinable from geometrical properties and optical properties of the light guide and optical properties of the light coupling device for each pixel of the at least one spatial light modulation device.

6. The display device as claimed in claim 5 , wherein a thickness and/or a possible curvature of the boundary surfaces of the light guide are usable as geometrical properties of the light guide to determine the light incidence position, where an index of refraction of the light guide material is usable as an optical property of the light guide.

7. The display device as claimed in claim 1 , wherein an image of the at least one spatial light modulation device is provided by means of the at least one light guiding device and the at least one optical system.

8. The display device as claimed in claim 1 , wherein a field of view, within which an item of information of a scene encoded in the at least one spatial light modulation device can be represented, is definable by propagation paths of different lengths of light from edge pixels of the at least one spatial light modulation device in the light guide and by a distance of the light guide to a provided observer position.

9. The display device as claimed in claim 1 , wherein a light source image of at least one light source provided in an illumination device or an image of the spatial light modulation device is provided by means of the optical system in the light path before coupling of the light into the light guiding device.

10. The display device as claimed in claim 9 , wherein the light coupling device is provided at or in a region of a position of a light source image.

11. The display device as claimed in claim 1 , wherein the light coupling device comprises at least one mirror element or at least one grating element, which is designed as a passive or controllable grating element.

12. The display device as claimed in claim 11 , wherein a grating constant of the grating element or an angle of inclination of the mirror element in relation to the surface of the light guide is usable as an optical property of the light coupling device for determining the light incidence position, which the light reaches after a defined number of reflections.

13. The display device as claimed in claim 1 , wherein the at least one light decoupling device is provided in the at least one light guiding device in such a way that the extension and the position of the light decoupling device comprises all light incidence positions which the light from different pixels of the spatial light modulation device reaches after a defined number of reflections on one of the boundary surfaces of the light guide.

14. The display device as claimed in claim 13 , wherein the light decoupling device comprises at least one grating element, in particular a deflection grating element, preferably an angle-selective deflection grating element, preferably a volume grating, or at least one mirror element.

15. The display device as claimed in claim 14 , wherein the at least one grating element is designed as controllable, where the grating period of the grating element is variably controllable in dependence on the light incidence position, which the light in the light guide reaches after a defined number of reflections, or in dependence on the light incidence angle, which the light in the light guide has after a defined number of reflections.

16. The display device as claimed in claim 1 , wherein the light guiding device comprises at least one retardation layer.

17. The display device as claimed in claim 1 , wherein the light guiding device comprises at least two retardation layers, where the at least two retardation layers each comprise a birefringent material, where the birefringent material of the at least two retardation layers is identical or different.

18. The display device as claimed in claim 17 , wherein the optical axis of the birefringent material of a first retardation layer is oriented in the plane of this layer, where the optical axis of the birefringent material of a second retardation layer is oriented perpendicularly to the plane of this layer.

19. The display device as claimed in claim 16 , wherein at least one retardation layer is applied on an outer surface of the light guide, and in that the index of refraction of this retardation layer and the propagation angle of the light propagating in the light guide are selected in such a way that total reflection of the light occurs at the boundary surface of this retardation layer to the surroundings of the light guide.

20. The display device as claimed in claim 16 , wherein the thickness of the at least one retardation layer and the birefringence and the alignment of the optical axis of the at least one retardation layer are each designed in such a way that upon incidence of linearly polarized light and for the average propagation angle of the light propagating in the light guide, after a first passage of the light through the at least one retardation layer, reflection is provided at the boundary surface to the surroundings of the light guide, and after a subsequent further passage of the light through the at least

Assignees

• Seereal Tech S A

Inventors

• Leister Norbert
• Kroll Bo
• Futterer Gerald

Classifications

• G02B27/0176 Primary

  characterised by mechanical features · CPC title

• G02B2027/0174

  holographic · CPC title

• G02B5/1828

  having means for producing variable diffraction (controlling the direction of light by means of one or more diffracting elements G02B26/0808; acousto-optical elements G02F1/11, G02F1/33; electro- or magneto-optical diffraction G02F1/292, G02F1/2955) · CPC title

• G02B6/0011

  the light guides being planar or of plate-like form · CPC title

• G02B2027/015

  involving arrangement aiming to get less bulky devices · CPC title