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1. WO2020115735 - SYSTÈME OPTIQUE D'ÉCLAIRAGE D'AFFICHAGE

Note: Texte fondé sur des processus automatiques de reconnaissance optique de caractères. Seule la version PDF a une valeur juridique

[ EN ]

CLAIMS

What is claimed is:

1. Display illumination optics for illuminating an image display device of an image generation apparatus, the display illumination optics comprising:

a source illumination distributor that includes an illumination waveguide having a front surface and a back surface opposite the front surface, the illumination waveguide being configured to internally direct light along a main direction,

wherein the illumination waveguide is configured to distribute the luminance of input illumination light launched into the illumination waveguide and propagating therein as waveguide-propagating illumination light along the main direction of the display illumination optics to obtain at back surface, along the main direction, output illumination light of desired luminance distribution for illuminating the image displace device that is configured to modulate the output illumination light to generate image-bearing light; and

wherein the illumination waveguide is further configured such that image-bearing light reflected from the image display device is directed towards the back surface to propagate through the illumination waveguide to emanate from the front surface.

2. The display illumination optics of claim 1, wherein the illumination waveguide comprises a plurality of partially reflective surfaces or diffraction gratings configured to let pass therethrough a portion of waveguide-propagating illumination light along the main direction and further configured to reflect a portion of waveguide-propagating illumination light coupled inside the illumination waveguide through the back surface towards an image display device for illumination thereof.

3. The display illumination optics of claim 1 or 2, wherein the plurality of partially reflective surfaces or diffraction gratings are slanted relative to the front surface and the back surface.

4. The display illumination optics of any of the claims 2 or 3, wherein the plurality of partially reflective surfaces or diffraction gratings are configured to reflect portions of light that is propagating in the illumination waveguide in total internal reflection (TIR) through the back surface towards the image display device.

5. The display illumination optics of any one of the claims 2 to 4, wherein the illumination waveguide comprises at least 2, at least 3, at least 4, at least 5, at least 10, or at least 20, partially reflective surfaces or diffraction gratings.

6. The display illumination optics of any one of the claims 2 to 5, wherein the plurality of partially reflective surfaces are polarizing or non-polarizing beam splitters.

7. The display illumination optics of claim 6, further comprising an optical retarder that is arranged between each two adjacent polarizing beam splitters a plurality of beam splitters and which is configured to change polarization of light emanating from a first polarizing beam splitter of the two adjacent polarizing beam splitters is changed before the light is incident onto a second polarizing beam splitter disposed downstream the first polarizing beam splitter such that a desired portion of light incident onto the second polarizing beam splitter is deflected towards the display image device by the second polarizing beam splitter arranged downstream the first polarizing beam splitter.

8. The display illumination optics of claim 7, wherein a polarizing beamsplitter that receives light reflected from a reflective image display device deflects the reflected light as reversely deflected image-bearing light towards one or more beam splitters which are arranged upstream the deflecting beam splitter, and which one or more upstream arranged beam splitters are configured to allow the reversely deflected image-bearing light pass therethrough further towards the input facet of the illumination waveguide to reduce or prevent crosstalk.

9. The display illumination optics of any one or more of claim 6 to 8, further comprising a polarization analyzer that is optically coupled with light emanating from the front surface.

10. The display illumination optics of any one of the claims 2 to 9, wherein the illumination waveguide comprises an output surface diffraction grating that is configured to diffract the input illumination light out of the back surface to obtain output illumination light that is propagating towards the image display device and that illuminates the image display device with desired luminance distribution.

11. The display illumination optics of any one of the claims 2 to 10, wherein input illumination light that is propagating in TIR in the illumination waveguide is diffracted or deflected through the back surface towards the image display device.

12. The display illumination optics of any one of the preceding claims, wherein the illumination waveguide has a length and width substantially matching the length and width of the image display device.

13. The display illumination optics of any one of the preceding claims, further comprising a light coupling structure for coupling light emitted by a light source by total internal reflection (TIR) into the illumination waveguide.

14. The display illumination optics of claim IB, wherein the light coupling structure comprises a coupling prism.

15. The display illumination optics according to any one of the preceding claim, wherein the light source is configured to emit light in one or more wavelengths.

16. The display illumination optics according to any one of the claims 13 to 15, wherein the light source is configured to emit white light.

17. An image generation apparatus for emitting image-bearing light, the image generation apparatus comprising:

an image display device; and

display illumination optics for illuminating the image display device, the display illumination optics comprising:

an illumination waveguide having a front surface and a back surface opposite the front surface and configured to internally direct light along a main direction between the front and back surface, wherein the illumination is configured to distribute the luminance of input illumination light launched into the illumination waveguide and propagating therein as waveguide-propagating illumination light along the main direction of the display illumination optics to obtain at the back surface, along the main direction, output illumination light of desired luminance distribution for illuminating the image displace device that is configured to modulate the output illumination light to generate image-bearing light;

wherein the image generation apparatus is further configured such that image bearing light reflected from the image display device is directed towards the back surface to propagate through the illumination waveguide to emanate from the front surface.

18. The image generation apparatus of claim 17, wherein the illumination waveguide comprises a plurality of partially reflective surfaces or diffraction gratings configured to let pass therethrough a portion of waveguide-propagating illumination light along the main direction and further being configured to reflect a portion of waveguide-propagating illumination light coupled inside the illumination waveguide through the back surface towards the image display device for illumination thereof

19. The image generation apparatus of claim 18, wherein the plurality of partially reflective surfaces or diffraction gratings of the illumination waveguide are slanted relative to the front and back surfaces of the illumination waveguide.

20. The image generation apparatus of claims 16 or 19, wherein the image display device comprises: a reflective display.

21. The image generation apparatus of claim 20, wherein the reflective display is based on a liquid crystal on silicon display, or based on a digital micromirror device.

22. The image generation apparatus of any one of the claims 18 to 21, wherein the plurality of partially reflective surfaces are polarizing or non-polarizing beam splitters.

23. The image generation apparatus of claim 22, further comprising an optical retarder that is arranged between each two adjacent polarizing beam splitters a plurality of beam splitters and which is configured to change polarization of light emanating from a first polarizing beam splitter of the two adjacent polarizing beam splitters is changed before the light is incident onto a second polarizing beam splitter disposed downstream the first polarizing beam splitter such that a desired portion of light incident onto the second polarizing beam splitter is deflected towards the display image device by the second polarizing beam splitter arranged downstream the first polarizing beam splitter.

24. The image generation apparatus of claim 23, wherein a polarizing beamsplitter that receives light reflected from a reflective image display device deflects the reflected light as reversely deflected image-bearing light towards one or more beam splitters which are arranged upstream the deflecting beam splitter, and which one or more upstream arranged beam splitters are configured to allow the reversely deflected image-bearing light pass therethrough further towards the input facet of the illumination waveguide to reduce or prevent crosstalk.

25. The image generation apparatus of any one or more of claim 22 to 24, further comprising a polarization analyzer that is optically coupled with light emanating from the front surface.

26. The image generation apparatus of any one of the claims 17 to 25, wherein the image generation apparatus comprises:

an input polarizer for generating S- or P-polarized light;

a reflective image display device comprising an alternate arrangement of at least one S- and P-modulating reflective display region that is configured and selectively controllable for generating correspondingly reflected S/P polarized image bearing light;

an S- or P- output polarizer for generating filtered S- or P- polarized image bearing light; and

at least one first P-polarization blocking filter which is arranged to block, in an S- polarized image bearing return path, the propagation of P-polarized light towards the output surface, and/or an S-polarization blocking filter which is arranged to block, in an P-polarized image bearing return path, the propagation of S-polarized light towards the output surface.

27. A method for illuminating an image display device of an image generation apparatus, the method comprising:

emitting input illuminating light by a light source;

introducing the input illuminating light into a source illumination distributor that includes an illumination waveguide having a front surface and a back surface opposite the front surface and which is configured to internally direct light along a main direction;

deflecting, with partially reflective surfaces or diffractive gratings, portions of waveguide-propagating illuminating light towards the image display device as output illumination light such that the image display device is lit with desired illuminance by the output illumination light to responsively generate image-bearing light that is reflected from the image display device towards the back surface, and such that the reflected image-bearing light further propagates through the partially reflective surfaces or diffractive gratings to emanate from the front surface of the illumination waveguide.

28. The method of illuminating an image display device of claim 27, further comprising directing the image-bearing light emanating from the front surface towards additional optics.

29. A method for manufacturing an illumination waveguide that is configured to illuminate an image display device, the method comprising:

providing a plurality of waveguide plates, each waveguide plate having an upper and a lower surface;

stacking the plurality of waveguide plates to obtain a stack of waveguide plates; and

cutting the stack of waveguide plates in a direction that is slanted relative to the upper and lower surfaces of the waveguide plates to obtain an illumination waveguide that comprises correspondingly slanted and partially reflective surfaces

wherein the illumination waveguide is configured to let pass therethrough a portion of waveguide-propagating illumination light along a main direction and to reflect, by the partially reflective surfaces, a portion of waveguide-propagating illumination light coupled inside the illumination waveguide through the back surface towards an image display device for illumination thereof to generate, by the image display device, reflected image-bearing light; and

wherein the illumination waveguide is further configured such that image-bearing light reflected from the image display device is directed towards the back surface to propagate through the partially reflective surfaces to emanate from the front surface.

30. A method for manufacturing an illumination waveguide that is configured to illuminate an image display device, the method comprising:

providing a waveguide slab having a front and back surface; and

disposing diffraction gratings on the front and/or the back surface of the waveguide slab,

wherein the diffraction gratings have a gradually increasing diffraction along a main direction of light propagating in the waveguide slab

such to let pass therethrough a portion of waveguide-propagating illumination light along a main direction and to diffract a portion of waveguide-propagating illumination light coupled inside the illumination waveguide through the back surface towards an image display device for illumination thereof and to generate, by the image display device, image-bearing light; and

wherein the illumination waveguide is configured such that image-bearing light reflected from the image display device is directed towards the back surface to propagate through the diffraction gratings to emanate from the front surface.