Devices for use in non-emissive displays

• US 20050018103A1
• Filed: 05/20/2004
• Published: 01/27/2005
• Est. Priority Date: 05/20/2003
• Status: Active Grant

• Current Assignee: Rambus Delaware LLC (Rambus Inc.)
• Original Assignee: Brilliant Film, LLC
• Inventors: Wojciechowski, Timothy J., Lubart, Neil D.
• Granted Patent: US 7,573,550 B2
• Time in Patent Office: Days
• US Class Current: 349/61
• CPC Class Codes: G02B 6/0053 Prismatic sheet or layer; Brightness enhancement element, sheet or layer
• CPC Class Codes: G02F 1/133555 Transflectors
• CPC Class Codes: G02F 1/133615 Edge-illuminating devices, i.e. illuminating from the side

Abstract

A liquid crystal module comprising a liquid crystal layer containing a plurality of pixels therein, a waveguide layer, and a reflective layer provided between the liquid crystal layer and the waveguide layer, the reflective layer includes a plurality of reflective areas and a plurality of apertures to permit light to pass therethrough. The waveguide layer can include a transparent material having first and second surfaces and a plurality of spaced-apart waveguide structures defining apertures therebetween disposed within the transparent material. The waveguide structures can be configured to guide light, entering the first surface of the transparent material, through the film and permit such light to exit the second surface of the transparent material.

Claims

1. An liquid crystal module comprising:

a liquid crystal layer containing a plurality of pixels therein;

a waveguide layer including;

a transparent material having first and second surfaces, the transparent material having a first index of refraction;

a plurality of spaced-apart waveguide structures defining apertures therebetween, the waveguide structures being disposed within the transparent film and having a second index of refraction different than the first index of refraction of the transparent material, the waveguide structures being configured to guide light, entering the first surface of the transparent material, through the film and permit such light to exit the second surface of the transparent material; and

a reflective layer provided between the liquid crystal layer and the waveguide layer, the reflective layer includes a plurality of reflective areas and a plurality of apertures to permit light to pass therethrough.

2. The liquid crystal module of claim 1, wherein the reflective layer is separated from the waveguide layer by a layer of air, glass, polymer or other transmissive material.

3. The liquid crystal module of claim 1, wherein the reflective and waveguide layers are not contiguous with each other.

4. The liquid crystal module of claim 1, wherein the reflective and liquid crystal layers are contiguous with each other.

5. The liquid crystal module of claim 1, wherein the liquid crystal layer, the reflective layer, and the waveguide layer are all aligned with each other such that:

each pixel in the liquid crystal layer is substantially aligned with two reflective areas separated by one of the apertures in the reflective layer, and

the apertures between each waveguide structure are substantially aligned with the apertures in the reflective layer.

6. The liquid crystal module of claim 5, wherein each waveguide structure has a base associated with the second surface of the transparent material, and each reflective area is substantially aligned with the base of one of the waveguide structures.

7. The liquid crystal module of claim 1, wherein the waveguide structures are defined by voids in the transparent material.

8. The liquid crystal module of claim 9, wherein the voids are filled with air, a metal, or polymer.

9. The liquid crystal module of claim 1 wherein the plurality of waveguide structures each include a triangular shaped cross-section having a base adjacent the second surface of the transparent material, and a pair of sidewalls that converge to an apex.

10. The liquid crystal module of claim 9, wherein the angle of each sidewall relative to the base of the triangular shaped waveguide structure is between about 76 degrees and less than 90 degrees.

11. The liquid crystal module of claim 9, wherein each of the plurality of waveguide structures has an aspect ratio of between about 2 and about 22.

12. The liquid crystal module of claim 1, further comprising a backlight assembly provided below the waveguide layer.

13. The liquid crystal module of claim 9, wherein:

light arriving from a first direction facing the first surface of the transparent material is guided by the waveguide structures and transmitted through the transparent material thereby exiting the second surface of the transparent material; and

light arriving from a second direction, opposite the first direction, is reflected by the reflecting areas of the reflecting layer back towards the second direction,

wherein the sum of the percentage of light being reflected back towards the second direction relative to the light arriving from the second direction, and the percentage of light being transmitted relative to the amount of light arriving from the first direction, is greater than 100 percent.

14. A device having transmissive and reflective properties for use in a non-emissive display having a backlight, the device comprising:

a transparent substrate including first and second surfaces, the transparent substrate having;

means for reflecting light arriving from a first direction back towards the first direction, and

means for transmitting light arriving from a second direction, opposite the first direction,

wherein the sum of the percentage of light being reflected back towards the first direction relative to the amount of light arriving from the first direction, and the percentage of light being transmitted through the transparent substrate relative to the amount of light arriving from the second direction, is greater than 100 percent when measured from a reference point facing the first surface, and

a light modification layer disposed on the first surface of the transparent substrate.

15. The device of claim 14, wherein the light reflecting means includes a plurality of spaced-apart reflective regions adjacent the first surface of the transparent substrate.

16. The device of claim 15, wherein the light transmitting means includes a plurality of waveguide structures, each waveguide structure being associated with each reflective region, each waveguide structure having an index of refraction different than the index of refraction of the transparent substrate.

17. The device of claim 16, wherein the light transmitting means is configured to guide light entering the second surface of the transparent substrate through the transparent substrate so that such light exits the first surface of the transparent substrate.

18. The device of claim 16, wherein the waveguide structure includes a base and converging sidewalls, the base being associated with the each reflective region.

19. The device of claim 14, wherein the light modification layer includes a polarizing layer configured to polarize reflected light and transmitted light orthogonal to each other.

20. The device of claim 19, wherein the polarizing layer has:

a plurality of reflecting linear polarizing regions, each reflecting linear polarizing region being substantially aligned with each reflective region of the light reflecting means, and

a plurality of transmissive linear polarizing regions, each reflecting linear polarizing region being substantially aligned with each aperture between each reflective region of the light reflecting means.

21. The device of claim 20, wherein the optic axes of the reflecting and transmissive linear polarizing regions are orthogonal to each other.

22. The device of claim 19, wherein the polarizing layer has:

a plurality of reflecting absorbing polarizing regions, each absorbing polarizing region being substantially aligned with each reflective region of the light reflecting means, and

a plurality of transmissive absorbing polarizing regions, each absorbing polarizing region being substantially aligned with each aperture between each reflective region of the light reflecting means.

23. The device of claim 22, wherein the optic axes of the reflecting and transmissive absorbing polarizing regions are orthogonal to each other.

24. The device of claim 23, wherein the transmissive absorbing polarizing regions transmit light from the transparent substrate, through the transmissive absorbing polarizing region, and cooperatively combine with the light from the reflective absorbing polarizing regions.

25. The device of claim 14, wherein the light modification layer includes a diffusing layer configured to appropriately scatter transmitted light.

26. The device of claim 25, wherein the diffusing layer has:

a plurality of reflecting diffusing regions, each reflecting polarizing region being substantially aligned with each reflective region of the light reflecting means, and

a plurality of transmissive diffusing regions, each reflecting polarizing region being substantially aligned with each aperture between each reflective region of the light reflecting means.

27. The device of claim 26, wherein the transfer function of the reflecting diffusing region is optimized by matching it to the transfer function of the reflecting region and the ambient light source.

28. The device of claim 26, wherein the transfer function of the transmissive diffusing region is optimized by matching it to the transfer function of the transparent substrate and the backlight.

29. A device having reflective and transmissive properties, the device comprising:

a transparent material having a first surface and a second surface, the transparent material having an index of refraction;

a plurality of spaced-apart waveguide structures disposed within the transparent material, each waveguide structure having a base and an index of refraction that is different than the index of refraction of the transparent material;

a plurality of reflective structures, each reflective structure being substantially aligned with and contiguous with each base of the waveguide structures; and

a light modification layer provided on the first surface of the transparent material.

30. The device of claim 29, wherein the light modification layer is selected from the group consisting of a linear polarizing layer, an absorbing layer, a diffusing layer, a collimating layer, and a quarter wave-plate layer.