Display device reflecting visible and infrared radiation

• US 6,034,752 A
• Filed: 03/22/1997
• Issued: 03/07/2000
• Est. Priority Date: 03/22/1997
• Status: Expired due to Term

• Current Assignee: Kent Displays Incorporated
• Original Assignee: Kent Displays Incorporated
• Inventors: Urban, Ellison C. II, Hoke, Kellie D., Huang, Xiao-Yang, Khan, Asad A., Davis, Donald J.
• Primary Examiner(s): Sikes, William L.
• Assistant Examiner(s): TON, MINH TOAN T
• Application Number:
  US08/823,329
• Time in Patent Office: 1,081 Days
• Field of Search: 349/169, 349/115, 349/176, 349/74, 349/81, 430/20, 430/312
• US Class Current: 349/74
• CPC Class Codes: G02F 1/13473 for wavelength filtering or for colour display without the use of colour mosaic filters
• CPC Class Codes: G02F 1/13718 based on a change of the texture state of a cholesteric liquid crystal

Abstract

A liquid crystal display device includes cell wall structure and a chiral nematic liquid crystal material. The cell wall structure and the liquid crystal cooperate to form focal conic and twisted planar textures that are stable in the absence of a field. A device applies an electric field to the liquid crystal for transforming at least a portion of the material to at least one of the focal conic and twisted planar textures. The liquid crystal material has a pitch length effective to reflect radiation having a wavelength in both the visible and the infrared ranges of the electromagnetic spectrum at intensity that is sufficient for viewing by an observer. One liquid crystal material may be disposed in a single region or two liquid crystal materials may be used, each in separate regions. One aspect of the invention is directed to a photolithography method for patterning a substrate of the display. The display may also have multicolor capabilities by including at least two materials that reflect visible light.

Claims

1. A liquid crystal display device comprising cell wall stricture and chiral nematic liquid crystal material, said cell wall structure and said liquid crystal cooperating to form focal conic and twisted planar textures that are stable in an absence of a field, and means for applying an electric field to said liquid crystal for transforming at least a portion of the material to at least one of the focal conic and twisted planar textures, wherein said liquid crystal material has a pitch length effective to reflect radiation including a portion having a wavelength in an visible range of an electromagnetic spectrum and a portion having a wavelength in an infrared range of the electromagnetic spectrum at intensity such that said visible portion and said infrared portion are able to be viewed by an observer.

2. The display device of claim 1 wherein said liquid crystal material has positive dielectric anisotropy.

3. The display device of claim 1 wherein at least about 20% of the radiation incident on said material is reflected by said material.

4. The display device of claim 1 wherein said cell wall structure forms a first region in which a first chiral nematic liquid crystal material is disposed and a second region in which a second chiral nematic liquid crystal material is disposed, wherein said first liquid crystal material reflects said visible portion of said radiation and said second liquid crystal material reflects said infrared portion of said radiation.

5. The display device of claim 1 wherein said chiral nematic liquid crystal material is disposed in a single region between opposing substrates, said material reflecting said visible portion of said radiation and said infrared portion of said radiation.

6. The display device of claim 4 wherein said first region is between a first substrate and a second substrate and said second region is between a third substrate and a fourth substrate.

7. The display device of claim 4 wherein said first region is between a first substrate and a second substrate and said second region is between said second substrate and a third substrate.

8. The display device of claim 4 wherein said first region and said second region are arranged in series with respect to one another in a direction from the display toward the observer.

9. The display device of claim 4 wherein said first region is located downstream of said second region with respect to a direction from the display toward the observer.

10. The display device of claim 6 wherein a spacing between said third substrate and said fourth substrate is at least about 4 microns.

11. The display device of claim 7 wherein a spacing between said second substrate and said third substrate is at least about 4 microns.

12. The display device of claim 5 wherein a spacing between said substrates ranges from about 4 to about 10 microns.

13. The display device of claim 1 wherein said material has an optical anisotropy of at least 0.10.

14. The display device of claim 1 wherein said radiation has a wavelength in the range of from about 400 to about 2 microns.

15. The display device of claim 4 wherein the visible portion of said radiation has a wavelength not greater than about 650 nm and the infrared portion of said radiation has a wavelength of at least about 700 nm.

16. The display device of claim 1 wherein said infrared portion of said radiation is adapted to be observed through an infrared detecting device.

58. The display device of claim 1 wherein said chiral nematic liquid crystal material is without polymer.

17. A liquid crystal display device comprising

cell wall structure and chiral nematic liquid crystal material, said cell wall structure and said liquid crystal cooperating to form focal conic and twisted planar textures that are stable in an absence of a field, wherein said cell wall structure forms a first region in which first chiral nematic liquid crystal material is disposed and a second region in which second chiral nematic liquid crystal material is disposed, said cell wall structure isolating said first chiral nematic liquid crystal material from communication with said second chiral nematic liquid crystal material;

and

means for applying an electric field for transforming at least a portion of said first liquid crystal material and said second liquid crystal material to at least one of the focal conic and twisted planar textures, wherein said first liquid crystal material has a pitch length effective to reflect radiation in an visible range of an electromagnetic spectrum and said second liquid crystal material has a pitch length effective to reflect radiation in an infrared range of the spectrum at intensity such that said visible radiation and said infrared radiation are able to be viewed by an observer.

18. The display device of claim 17 wherein said liquid crystal material has positive dielectric anisotropy.

19. The display device of claim 17 wherein at least about 20% of the radiation incident on said first material and said second material is reflected from said first material and said second material.

20. The display device of claim 17 wherein said first region is between a first substrate and a second substrate and said second region is between a third substrate and a fourth substrate.

21. The display device of claim 17 wherein said first region is between a first substrate and a second substrate and said second region is between said second substrate and a third substrate.

22. The display device of claim 17 wherein said first region and said second region are arranged in series with respect to one another in a direction from the display toward the observer.

23. The display device of claim 17 wherein said first region is located downstream of said second region with respect to a direction from the display toward the observer.

24. The display device of claim 23 further comprising one of a colored paint or a black paint that is transparent to infrared radiation, said paint being disposed adjacent and downstream of the second liquid crystal material with respect to said direction.

25. A liquid crystal display device comprising cell wall structure and chiral nematic liquid crystal material, said cell wall structure and said liquid crystal cooperating to form focal conic and twisted planar textures that are stable in an absence of a field, wherein said chiral nematic liquid crystal material is disposed in a single region between opposing substrates, and means for applying an electric field to said liquid crystal for transforming at least a portion of the material to at least one of the focal conic and twisted planar textures, wherein said liquid crystal material has a pitch length effective to reflect radiation including a portion having a wavelength in an visible range of an electromagnetic spectrum and a portion having a wavelength in an infrared range of the electromagnetic spectrum at intensity such that said visible portion and said infrared portion are able to be viewed by an observer.

26. The display device of claim 25 wherein said liquid crystal material has positive dielectric anisotropy.

27. The display device of claim 25 wherein at least about 20% of the radiation incident upon said material is reflected from said material.

28. The display device of claim 25 wherein a spacing between said substrates ranges from about 4 to about 10 microns.

29. The display device of claim 25 wherein said material has an optical anisotropy of at least 0.10.

30. In instrumentation of the type that is viewed by personnel employing a night vision detector, said instrumentation producing light having a wavelength in the visible range of the electromagnetic spectrum, said improvement comprising a liquid crystal display device comprising cell wall structure and a chiral nematic liquid crystal material, said cell wall structure and said liquid crystal cooperating to form focal conic and twisted planar textures that are stable in an absence of a field, and means for applying an electric field to said liquid crystal for transforming at least a portion of the material to at least one of the focal conic and twisted planar textures, wherein said liquid crystal material has a pitch length effective to reflect radiation including a portion having a wavelength in an visible range of an electromagnetic spectrum and a portion having a wavelength in an infrared range of the spectrum at intensity such that said visible portion and said infrared portion are able to be viewed by said personnel.

31. The improvement of claim 30 wherein said liquid crystal material has positive dielectric anisotropy.

32. The improvement of claim 30 wherein at least about 20% of the radiation incident upon said material is reflected from said material.

33. The improvement of claim 30 wherein said cell wall structure forms a first region in which a first chiral nematic liquid crystal material is disposed and a second region in which a second chiral nematic liquid crystal material is disposed, wherein said first liquid crystal reflects said visible portion of said radiation and said second liquid crystal reflects said infrared portion of said radiation.

34. The improvement of claim 30 wherein said chiral nematic liquid crystal material is disposed in a single region between opposing substrates, said liquid crystal reflecting said visible portion of said radiation and said infrared portion of said radiation.

35. The improvement of claim 30 wherein said first region is between a first substrate and a second substrate and said second region is between a third substrate and a fourth substrate.

36. The improvement of claim 30 wherein said first region is between a first substrate and a second substrate and said second region is between said second substrate and a third substrate.

37. The improvement of claim 30 wherein said first region and said second region are arranged in series with respect to one another in a direction from the display toward said personnel.

38. The improvement of claim 30 wherein said first region is located downstream of said second region with respect to a direction from the display toward said personnel.

39. The improvement of claim 30 wherein said material has an optical anisotropy of at least about 0.10.

40. The improvement of claim 30 wherein the night vision detector comprises night vision goggles and said personnel can view said display device with and without said night vision goggles.

41. A method of making a display, comprising the steps of:

adjusting the pitch length of chiral nematic liquid crystal material so that the material reflects radiation including a portion having a wavelength in an visible range of an electromagnetic spectrum and a portion having a wavelength in an infrared range of the electromagnetic spectrum;

spacing apart opposing substrates at a distance effective to provide said visible portion and said infrared portion with intensity such that said visible portion and said infrared portion are able to be viewed by an observer;

filling said material between said substrates such that said cell wall structure cooperates with said liquid crystal to form focal conic and twisted planar textures that are stable in an absence of a field; and

connecting to said substrates means for applying an electric field to said liquid crystal for transforming at least a portion of the material to at least one of the focal conic and twisted planar textures.

42. The method of claim 41 wherein said liquid crystal material has positive dielectric anisotropy.

43. The method of claim 41 wherein a first chiral nematic liquid crystal that reflects said visible portion of said radiation is filled between opposing substrates of a first cell wall structure and a second chiral nematic liquid crystal that reflects said infrared portion of said radiation is filled between opposing substrates of a second cell wall structure.

44. The method of claim 41 wherein said chiral nematic liquid crystal material is filled between opposing substrates of a single cell wall structure, said liquid crystal material reflecting said visible portion of said radiation and said infrared portion of said radiation.

45. The method of claim 44 wherein said material has an optical anisotropy of at least about 0.10.

46. A liquid crystal display device comprising

cell wall structure and chiral nematic liquid crystal material, said cell wall structure and said liquid crystal cooperating to form focal conic and twisted planar textures that are stable in the absence of a field, wherein said cell wall structure forms a first region in which a first chiral nematic liquid crystal material is disposed, a second region in which a second chiral nematic liquid crystal material is disposed and a third region in which a third chiral nematic material is disposed, said cell wall structure isolating said first material, said second material and said third material from communication with each other;

and

means for applying an electric field for transforming at least a portion of said first liquid crystal, said second liquid crystal and said third liquid crystal to at least one of the focal conic and twisted planar textures, wherein each of said first material and said second material has a pitch length effective to reflect radiation in an visible range of an electromagnetic spectrum and said third material has a pitch length effective to reflect radiation in an infrared range of the spectrum at intensity such that said visible radiation reflected by said first material, said visible radiation reflected by said second material and said infrared radiation are able to be viewed by an observer.

47. The display device of claim 46 further comprising at least one other region in which a liquid crystal material that has a pitch length effective to reflect light in the visible range is disposed.

48. The display device of claim 46 wherein said first liquid crystal material has a pitch length effective to reflect light of a first color and said second liquid crystal material has a pitch length effective to reflect light of a second color.

49. The display device of claim 46 wherein said first region is between a first substrate and a second substrate, said second region is between a third substrate and a fourth substrate, and said third region is between a fifth substrate and a sixth substrate.

50. The display device of claim 46 wherein said first region is between a first substrate and a second substrate, said second region is between said second substrate and a third substrate, and said third region is between said third substrate and a fourth substrate.

51. The display device of claim 46 wherein said first region and said second region are arranged downstream of said third region with respect to a direction from the display toward the observer.

52. The display device of claim 46 wherein the cell wall structure comprises at least five substrates and a colored material is adjacent one of the substrates that has an electrode on only one side.

53. The display device of claim 46 wherein the cell wall structure comprises at least four substrates and a black material is adjacent an outer one of said substrates.

61. The display device of claim 46 comprising a layer of black material disposed upstream of said third region relative to a direction of incident light which allows passage of infrared radiation to said third region.

54. A liquid crystal display device comprising cell wall structure and chiral nematic liquid crystal material, said cell wall structure and said liquid crystal cooperating to form focal conic and twisted planar textures that are stable in an absence of a field, and means for applying an electric field to said liquid crystal for transforming at least a portion of the material to at least one of the focal conic and twisted planar textures, wherein said liquid crystal material has a pitch length effective to reflect radiation having a wavelength in an visible range of an electromagnetic spectrum and radiation having a wavelength in an infrared range of the electromagnetic spectrum at intensity such that said visible radiation and a portion of said infrared radiation of at least 780 nm are able to be viewed by an observer.

55. The display device of claim 54 wherein said cell wall structure includes a first region in which a first chiral nematic liquid crystal material is disposed and a second region in which a second chiral nematic liquid crystal material is disposed, said cell wall structure isolating said first material from communication with said second material, wherein said first material reflects said visible radiation and said second material reflects said infrared radiation.

56. The display device of claim 54 wherein said chiral nematic liquid crystal material is disposed in a single region between opposing substrates, said material reflecting both said visible radiation and said infrared radiation.

57. A liquid crystal display device comprising cell wall structure and chiral nematic liquid crystal material, said cell wall structure and said liquid crystal cooperating to form focal conic and twisted planar textures that are stable in an absence of a field, and means for applying an electric field to said liquid crystal for transforming at least a portion of the material to at least one of the focal conic and twisted planar textures, said liquid crystal material having a pitch length effective to reflect radiation having a wavelength in an visible range of an electromagnetic spectrum, said liquid crystal material having a pitch length effective to reflect radiation having a wavelength in an infrared range of the electromagnetic spectrum that extends at least up to an upper wavelength of detection of an infrared detector, wherein intensity of said visible radiation and said infrared radiation enable said visible radiation and said infrared radiation to be viewed by an observer.

59. A liquid crystal display device comprising:

first chiral nematic liquid crystal material comprising liquid crystal having a pitch length effective to reflect visible light of a first color, second chiral nematic liquid crystal material comprising liquid crystal having a pitch length effective to reflect visible light of a second color, third chiral nematic liquid crystal material comprising liquid crystal having a pitch length effective to reflect light of a third color, and fourth chiral nematic liquid crystal material having a pitch length effective to reflect infrared radiation, the liquid crystal of said first material, said second material, said third material and said fourth material having positive dielectric anisotropy;

planar substrates that form therebetween a first region in which said first material is disposed, a second region in which said second material is disposed, a third region in which said third material is disposed, and a fourth region in which said fourth material is disposed, wherein said first region, said second region, said third region and said fourth region are stacked relative to each other;

wherein said substrates cooperate with said first material, said second material, said third material, and said fourth material to form in said first region, said second region, said third region and said fourth region, focal conic and twisted planar textures that are stable in an absence of a field; and

addressing means for applying an electric field for transforming at least a portion of the liquid crystal of at least one of said first material, said second material, said third material and said fourth material, to at least one of the focal conic and twisted planar textures.

60. The display device of claim 59 comprising a layer of black material disposed upstream of said fourth region relative to a direction of incident light which allows passage of infrared radiation to said fourth region.