DIFFRACTIVE LIQUID CRYSTAL DISPLAY

• US 20100026930A1
• Filed: 07/28/2009
• Published: 02/04/2010
• Est. Priority Date: 07/28/2008
• Status: Active Grant

• Current Assignee: John Gilmore
• Original Assignee: Pixel Qi Corporation
• Inventors: Jepsen, Mary Lou
• Granted Patent: US 8,384,861 B2
• Time in Patent Office: Days
• US Class Current: 349/62
• CPC Class Codes: G02B 5/18 Diffraction gratings holographic optical elements G02B5/32, G03H; integrally combined with optical fibres G02B6/02057; for coupling light guides G02B6/34; integrally combined with optical integrated light guides G02B6/12; grating systems G02B27/44
• CPC Class Codes: G02B 5/1842 Gratings for image generation G02B5/1847 takes precedence
• CPC Class Codes: G02F 1/133555 Transflectors
• CPC Class Codes: G02F 1/133607 the light controlling member including light directing or refracting elements, e.g. prisms or lenses
• CPC Class Codes: G02F 1/133615 Edge-illuminating devices, i.e. illuminating from the side
• CPC Class Codes: G02F 1/133618 for ambient light
• CPC Class Codes: G02F 2201/305 diffraction grating
• CPC Class Codes: G02F 2203/62 Switchable arrangements whereby the element being usually not switchable

Abstract

A liquid crystal display (LCD) comprises a light source; a light diffractor over the light source configured to diffract light received from the light source; a liquid crystal diffraction grating over the light diffractor and between liquid crystal pixel structures comprising a plurality of liquid crystal pixels; the liquid crystal diffraction grating has a changed diffraction index in response to application of a voltage differential across the diffraction grating, and when having the changed diffraction index aligns diffracted light received from the light diffractor into aligned light directed toward the liquid crystal pixel structure. An LCD may comprise a plurality of liquid crystal pixels each comprising a reflective part and a transmissive part, the reflective part of at least some of the plurality of liquid crystal pixels comprising a retroreflector configured to reflect at least some light rays, received from an external light source, toward the external light source.

Claims

1. A liquid crystal display (LCD) comprising:

a light source;

a light diffractor over the light source configured to diffract light received from the light source;

a liquid crystal diffraction grating over the light diffractor and between liquid crystal pixel structures comprising a plurality of liquid crystal pixels;

wherein the liquid crystal diffraction grating is configured to have a changed diffractive property in response to application of a voltage differential across the diffraction grating, and configured when having the changed diffractive property to align diffracted light received from the light diffractor into aligned light directed toward the liquid crystal pixel structures.

2. The LCD of claim 1 wherein the light diffractor comprises any of a prism film or a second diffraction grating.

3. The LCD of claim 1 wherein the light diffractor is configured to diffract light within a range of specular angles, and wherein the liquid crystal diffraction grating is configured to align diffracted light received in the same range of specular angles.

4. The LCD of claim 1 wherein the liquid crystal diffraction grating comprises a plurality of grooves and walls having a period ranging from 0.1 microns to 10 microns and having a groove depth ranging from 0.1 microns to 10 microns.

5. The LCD of claim 1 wherein the liquid crystal diffraction grating comprises a plurality of grooves and walls having a period of 0.5 microns and having a groove depth of 2 microns.

6. The LCD of claim 1 wherein each of the plurality of liquid crystal pixels comprises a reflective part and a transmissive part, wherein the reflective part has only part of a color filter, and at least part of the transmissive part comprises one or more color-filters that mostly or completely cover the transmissive part of the pixel.

7. The LCD of claim 6 wherein the liquid crystal diffraction grating is over only the transmissive part of each of the plurality of liquid crystal pixels.

8. The LCD of claim 6 wherein the reflective part occupies opposite corners of the plurality of pixels.

9. The LCD of claim 6 wherein the transmissive part is diagonally arranged.

10. The LCD of claim 6 wherein 1% to 50% of the reflective part has a color filter.

11. A liquid crystal display (LCD) comprising:

a plurality of liquid crystal pixels each comprising a reflective part and a transmissive part;

the reflective part of at least some of the plurality of liquid crystal pixels comprising a retroreflector configured to reflect at least some light rays, received from an external light source, toward the external light source.

12. The LCD of claim 11 wherein the reflective part of all the plurality of liquid crystal pixels comprises the retroreflector.

13. The LCD of claim 11 wherein the retroreflector is configured to reflect, toward the external light source, zero-th order non-diffracted light rays received from the external light source.

14. The LCD of claim 11 wherein the retroreflector is integrally formed with one or more colorless spacers over the reflective part.

15. The LCD of claim 11 wherein the retroreflector is formed in a thin film transistor (TFT) layer of the LCD.

16. The LCD of claim 11, further comprising:

a back light source;

a light diffractor over the back light source configured to diffract light received from the back light source;

a liquid crystal diffraction grating over the light diffractor and under a liquid crystal pixel structure comprising a plurality of liquid crystal pixels;

wherein the liquid crystal diffraction grating is configured to have a changed diffraction index in response to application of a voltage differential across the diffraction grating, and configured when having the changed diffraction index to align diffracted light received from the light diffractor into aligned light directed toward the liquid crystal pixel structure.

17. A computing device, comprising:

one or more processors;

a liquid crystal display comprising a light source, a light diffractor over the light source configured to diffract light received from the light source, and a liquid crystal diffraction grating over the light diffractor and under a liquid crystal pixel structure comprising a plurality of liquid crystal pixels;

wherein the liquid crystal diffraction grating is configured to have a changed diffraction index in response to application of a voltage differential across the diffraction grating, and configured when having the changed diffraction index to align diffracted light received from the light diffractor into aligned light directed toward the liquid crystal pixel structure.

18. The computing device of claim 17 wherein the light diffractor comprises any of a prism film or a second diffraction grating.

19. The computing device of claim 17 wherein the light diffractor is configured to diffract light within a range of specular angles, and wherein the liquid crystal diffraction grating is configured to align diffracted light received in the same range of specular angles.

20. The computing device of claim 17 wherein the liquid crystal diffraction grating comprises a plurality of grooves and walls having a period ranging from 0.1 microns to 10 microns and having a groove depth ranging from 0.1 microns to 10 microns.

21. The computing device of claim 17 wherein the liquid crystal diffraction grating comprises a plurality of grooves and walls having a period of 0.5 microns and having a groove depth of 2 microns.

22. The computing device of claim 17 comprising any of a laptop computer, notebook, netbook, handheld computer, personal digital assistant, or cell phone.

23. A computing device, comprising:

one or more processors;

a liquid crystal display (LCD) coupled to the one or more processors and comprising a plurality of liquid crystal pixels each comprising a reflective part and a transmissive part;

the reflective part of at least some of the plurality of liquid crystal pixels comprising a retroreflector configured to reflect at least some light rays, received from an external light source, toward the external light source.

24. The computing device of claim 23 wherein the reflective part of all the plurality of liquid crystal pixels comprises the retroreflector.

25. The computing device of claim 23 wherein the retroreflector is configured to reflect, toward the external light source, zero-th order non-diffracted light rays received from the external light source.

26. The computing device of claim 23 wherein the retroreflector is integrally formed with one or more colorless spacers over the reflective part.

27. The computing device of claim 23 wherein the retroreflector is formed in a thin film transistor (TFT) layer of the LCD.

28. The computing device of claim 23 further comprising:

a back light source;

a light diffractor over the back light source configured to diffract light received from the back light source;

a liquid crystal diffraction grating over the light diffractor and under a liquid crystal pixel structure comprising a plurality of liquid crystal pixels;

wherein the liquid crystal diffraction grating is configured to have a changed diffraction index in response to application of a voltage differential across the diffraction grating, and configured when having the changed diffraction index to align diffracted light received from the light diffractor into aligned light directed toward the liquid crystal pixel structure.

29. The computing device of claim 23 comprising any of a laptop computer, notebook, netbook, handheld computer, personal digital assistant, or cell phone.