Image display system and electrically actuatable image combiner therefor

• US 20020171940A1
• Filed: 04/23/2002
• Published: 11/21/2002
• Est. Priority Date: 04/23/2001
• Status: Active Grant

• Current Assignee: Reveo, Inc.
• Original Assignee: Reveo, Inc.
• Inventors: He, Zhan, Lin, Jaujeng
• Granted Patent: US 6,844,980 B2
• Time in Patent Office: Days
• US Class Current: 359/630
• CPC Class Codes: G02B 2027/0118 comprising devices for improving the contrast of the display / brillance control visibility
• CPC Class Codes: G02B 27/01 Head-up displays
• CPC Class Codes: G02B 27/017 Head mounted

Abstract

The present invention is directed to an image display system for displaying an image in a user'"'"'s line of sight including an image combiner that is electrically actuatable. The image display system generally includes an image projection device, and an electrically actuatable image combiner. The image combiner may be superposed with a transparent substrate such as a visor or a windshield.

Claims

1. An image display system for displaying an image in a user'"'"'s line of sight, said image display system comprising:

an image projection device; and

an image combiner being electrically actuatable between first and second states.

2. The image display system of claim 1 comprising a helmet mounted display.

3. The image display system of claim 2 wherein said image combiner is disposed on a visor.

4. The image display system of claim 1 comprising a windshield display.

5. The image display system of claim 4 wherein said image combiner is disposed on a motor vehicle windshield.

6. The image display system of claim 1 wherein said image projection device comprises a liquid crystal display.

7. The image display system of claim 1 wherein said image projection device comprises a cathode ray tube.

8. The image display system of claim 1 wherein said image projection device projects said image within a narrow band spectrum of light.

9. The image display system of claim 1 wherein said image combiner comprises at least one cholesteric liquid crystal layer having a reflection band.

10. The image display system of claim 9 wherein said reflection band is narrow.

11. The image display system of claim 10 wherein said reflection band has a center wavelength of about 540 nm and a bandwidth of less than about 100 nm.

12. The image display system of claim 9 wherein said at least one cholesteric liquid crystal layer comprises a mixture of a cholesteric liquid crystal material and another liquid crystal material having a molecular weight less than about 5000.

13. The image display system of claim 12 wherein said cholesteric liquid crystal layer comprises a mixture of a first material, a second material and a third material, said first material being a cholesteric liquid crystal material, said second material being a liquid crystal material having a molecular weight less than about 5000, and said third material being a chiral material.

14. The image display system of claim 9 including one cholesteric liquid crystal layer disposed between two optically transparent, electrically conductive substrates.

15. The image display system of claim 14 wherein each of said two optically transparent, electrically conductive substrates comprise indium tin oxide.

16. The image display system of claim 9 comprising two cholesteric liquid crystal layers with an optically transparent, electrically conductive interlayer disposed therebetween.

17. The image display system of claim 16 wherein said two cholesteric liquid crystal layers are disposed between two optically transparent, electrically conductive substrates.

18. The image display system of claim 17 wherein said two substrates and said interlayer each comprise indium tin oxide.

19. The image display system of claim 17 wherein said two substrates each comprise an indium tin oxide coated glass substrate.

20. The image display system of claim 17 wherein said two substrates each comprise an indium tin oxide coated plastic substrate.

21. The image display system of claim 1 further comprising a driving circuit for actuating and deactuating said image combiner, said driving circuit comprising a power supply.

22. The image display system of claim 21 wherein said driving circuit provides a voltage in the range from about 0 to about 50 volts.

23. The image display system of claim 20 wherein optically transparent couplers are used to couple said driving circuit to said image combiner.

24. The image display system of claim 23 wherein said optically transparent couplers comprise indium tin oxide.

25. The image display system of claim 1 wherein said image combiner is disposed on an optically transparent substrate with an optically transparent adhesive.

26. The image display system of claim 25 wherein said optically transparent adhesive comprises a UV curable adhesive.

27. The image display system of claim 1 wherein actuation of said image combiner from said first state to said second state substantially reduces the reflectivity of said image combiner.

28. The image display system of claim 1 wherein deactuation of said image combiner from said second state to said first state substantially increases the reflectivity of said image combiner.

29. The image display system of claim 1 wherein the reflectivity of said image combiner in said first state within a narrow spectrum of wavelengths is greater than about 90%.

30. The image display system of claim 1 wherein the reflectivity of said image combiner in said second state within a narrow spectrum of wavelengths is less than about 10%.

31. The image display system of claim 1 wherein the reflectivity of said image combiner within a narrow spectrum of wavelengths may be electrically controlled over a range from less than about 10% to greater than about 90%.

32. An image combiner for a heads up display comprising:

at least one cholesteric liquid crystal layer;

at least two optically transparent, electrically conductive substrates; and

said image combiner being actuatable between first and second states.

33. The image combiner of claim 32 wherein said at least one cholesteric liquid crystal layer comprises a mixture of a cholesteric liquid crystal material and another liquid crystal material having a molecular weight of less than about 5000.

34. The image combiner of claim 33 wherein said at least one cholesteric liquid crystal layer comprises a mixture of a first material, a second material and a third material, said first material being a cholesteric liquid crystal material, said second material being a liquid crystal material having a molecular weight of less than about 5000, and said third material being a chiral material.

35. The image combiner of claim 32 having a reflection band with a center wavelength of about 540 nm and a bandwidth of less than about 100 nm.

36. The image combiner of claim 32 comprising two cholesteric liquid crystal layers with an optically transparent, electrically conductive interlayer disposed therebetween.

37. The image combiner of claim 36 wherein said two cholesteric liquid crystal layers are disposed between two of said at least two optically transparent, electrically conductive substrates.

38. The image combiner of claim 37 wherein said at least two optically transparent, electrically conductive substrates and said interlayer each comprise indium tin oxide.

39. The image combiner of claim 32 wherein said at least two optically transparent, electrically conductive substrates each comprise an indium tin oxide coated glass substrate.

40. The image combiner of claim 32 wherein said at least two optically transparent, electrically conductive substrates each comprise an indium tin oxide coated plastic substrate.

41. The image combiner of claim 32 having a reflectivity within a narrow spectrum of wavelengths greater than about 90% when said image combiner is disposed in said first state.

42. The image combiner of claim 32 having a reflectivity within a narrow spectrum of wavelengths less than about 10% when said image combiner is disposed in said second state.

43. The image combiner of claim 32 wherein the reflectivity within a narrow spectrum of wavelengths may be electrically controlled over a range from less than about 10% to greater than about 90%.

44. A method for fabricating a heads up display system, said method comprising:

providing an image projection device;

providing an image combiner including at least one cholesteric liquid crystal layer, said image combiner being electrically actuatable between first and second states;

providing a driving circuit;

electrically connecting said image combiner with said driving circuit; and

locating said image projection device for projecting images on said image combiner.

46. The method of claim 45 wherein said electrically actuating and deactuating said image combiner further comprises electrically controlling the brightness of the projected image.

45. A method for positioning an image in a user'"'"'s line of sight, said method comprising:

positioning an image combiner including at least one cholesteric liquid crystal layer in the user'"'"'s line of sight, said image combiner being electrically actuatable between first and second states;

projecting an image to be combined with an image in user'"'"'s line of sight on said image combiner; and

selectively electrically actuating and deactuating said image combiner, wherein actuation of said image combiner from said first state to said second state substantially reduces the brightness of the projected image, and deactuation of said image combiner from said second state to said first state substantially increases the brightness of the projected image.