LCD element including regions where helical axes of LC molecules of neighboring domains in focalconic state extend in same direction

• US 6,947,114 B2
• Filed: 07/29/2004
• Issued: 09/20/2005
• Est. Priority Date: 06/30/2000
• Status: Expired due to Fees

• Current Assignee: Minolta Co., Ltd. (Konica Minolta Inc.)
• Original Assignee: Minolta Co., Ltd. (Konica Minolta Inc.)
• Inventors: Okada, Masakazu, Yamada, Jun, Miyai, Mitsuyoshi, Hashimoto, Kiyofumi
• Primary Examiner(s): CHOWDHURY, TARIFUR RASHID
• Application Number:
  US10/901,885
• Publication Number:
  US 20050007531A1
• Time in Patent Office: 418 Days
• Field of Search: 349/129, 349/169, 349/175, 349/185
• US Class Current: 349/129
• CPC Class Codes: G02F 1/133707 Structures for producing distorted electric fields, e.g. bumps, protrusions, recesses, slits in pixel electrodes
• CPC Class Codes: G02F 1/133753 with different alignment orientations or pretilt angles on a same surface, e.g. for grey scale or improved viewing angle
• CPC Class Codes: G02F 1/133757 with different alignment orientations
• CPC Class Codes: G02F 1/1347 Arrangement of liquid crystal layers or cells in which the final condition of one light beam is achieved by the addition of the effects of two or more layers or cells
• CPC Class Codes: G02F 1/13718 based on a change of the texture state of a cholesteric liquid crystal

Abstract

A liquid crystal light modulation element is provided that includes a liquid crystal layer held between a pair of substrates. The liquid crystal layer includes a liquid crystal material that exhibits a cholesteric phase and has a plurality of domains. The liquid crystal layer includes regions where the helical axes of the liquid crystal molecules in a focal conic state extend in regular directions within a plane that is substantially parallel to the surface substrate.

Claims

1. A liquid crystal light modulation element for performing light modulation by utilizing a focal conic state of liquid crystal molecules included in a liquid crystal layer having a plurality of liquid crystal domains and held between a pair of substrates, wherein the liquid crystal layer includes regions in which helical axes of the liquid crystal molecules of neighboring liquid crystal domains in the focal conic state extend in directions which are substantially the same and substantially parallel to a substrate surface, and thereby the helical axes of the liquid crystal molecules in the focal conic state extend in regular directions within a plane substantially parallel to a substrate surface.

2. A liquid crystal light modulation element according to claim 1, wherein

a region providing a different orientation regulating force is arranged partially on a surface of at least one of the substrates in contact with the liquid crystal for orienting helical axes of the liquid crystal molecules in regular directions.

3. A liquid crystal light modulation element according to claim 2, wherein

an orientation film is arranged on the surface, in contact with the liquid crystal, of the substrate provided with said region.

4. A liquid crystal light modulation element according to claim 3, wherein

said region is formed by partially effecting rubbing.

5. A liquid crystal light modulation element according to claim 3, wherein

said region is formed by partially effecting light irradiation.

6. A liquid crystal light modulation element according to claim 2, wherein

said region is formed by partially effecting rubbing.

7. A liquid crystal light modulation element according to claim 3, wherein

said region is formed by partially effecting light irradiation.

8. A liquid crystal light modulation element according to claim 2, wherein

said region is formed by partially using a different material.

9. A liquid crystal light modulation element according to claim 2, wherein

a width W of said region of the different orientation regulating force and a helical pitch p of the liquid crystal molecules satisfy a relationship of p<

W<

20p.

10. A liquid crystal light modulation element according to claim 2, wherein

an arrangement pitch L of said regions of the different orientation regulating force and a helical pitch p of the liquid crystal molecules satisfy a relationship of 5p<

L<

100p.

11. A liquid crystal light modulation element according to claim 10, wherein

said arrangement pitch L of said regions of the different orientation regulating force is not uniform within a range satisfying said relationship.

12. A liquid crystal light modulation element according to claim 2, comprising:

a plurality of pixels arranged in a direction different from a direction of arrangement of said regions of the different orientation regulating force.

13. A liquid crystal light modulation element according to claim 2, comprising:

a plurality of regions which are different in a direction of arrangement of said regions of the different orientation regulating force.

14. A multilayer liquid crystal light modulation element comprising a plurality of liquid crystal light modulation elements stacked together in which an element according to claim 1 is included.

15. A multilayer liquid crystal light modulation element according to claim 14, wherein

at least the element on the end of the front side is the element according to claim 1.

16. A multilayer liquid crystal light modulation element according to claim 14, wherein

the elements have different peak wavelengths of selective reflection, respectively.

17. A multilayer liquid crystal light modulation element according to claim 14, comprising:

at least two liquid crystal layers having different optical rotation directions, respectively.

18. A multilayer liquid crystal light modulation element according to claim 17, wherein

said liquid crystal layers having different optical rotation directions have a substantially equal peak wavelength of selective reflection.

19. A multilayer liquid crystal light modulation element comprising an element according to claim 1 and an element stacked together with said element and containing liquid crystal molecules having helical axes extending irregularly in a plane substantially parallel to a substrate surface when being in the focal conic state.

20. A liquid crystal light modulation element according to claim 19, wherein

at least the element on the end of the front side is the element according to claim 1.

21. A multilayer liquid crystal light modulation element according to claim 19, wherein

the elements have different peak wavelengths of selective reflection, respectively.

22. A multilayer liquid crystal light modulation element according to claim 19, comprising:

at least two liquid crystal layers having different optical rotation directions, respectively.

23. A multilayer liquid crystal light modulation element according to claim 22, wherein

said liquid crystal layers having different optical rotation directions have a substantially equal peak wavelength of selective reflection.

24. A liquid crystal light modulation element according to claim 1, wherein

the liquid crystal exhibiting the focal conic state is a liquid crystal exhibiting a cholesteric phase at a room temperature.

25. A liquid crystal light modulation element according to claim 24, wherein

the liquid crystal exhibiting the focal conic state is a liquid crystal having positive dielectric anisotropy.

26. A liquid crystal light modulation element according to claim 1, wherein

display is performed by switching the liquid crystal between the focal conic state and a planar state.

27. A liquid crystal light modulation element according to claim 26, wherein

the liquid crystal in the planar state has a peak of selective reflection in a visible wavelength range.

28. A liquid crystal light modulation element for performing light modulation by utilizing a focal conic state of liquid crystal molecules included in a liquid crystal layer having a plurality of liquid crystal domains and held between a pair of substrates, wherein the liquid crystal layer includes regions in which helical axes of the liquid crystal molecules of neighboring liquid crystal domains in the focal conic state are extended in directions which are substantially the same and substantially parallel to a substrate surface by orientation regulating means for orienting the helical axes of the liquid crystal molecules in the focal conic state, and thereby the helical axes of the liquid crystal molecules in the focal conic state are extended in regular directions within the plane substantially parallel to the substrate surface.

29. A liquid crystal light modulation element according to claim 28, wherein

the orientation regulating means orients the helical axes of the liquid crystal molecules in the focal conic state along the regular directions when a predetermined electric field is applied across the substrates.

30. A liquid crystal light modulation element according to claim 29, wherein

the orientation regulating means orients the helical axes of the liquid crystal molecules in the focal conic state along the regular directions by causing anisotropy in directions of lines of electric force of the electric field.

31. A liquid crystal light modulation element according to claim 30, wherein

the orientation regulating means is a projected structure formed on at least one of the substrates, and the anisotropy is caused in the directions of the equal potential lines of said electric field by the projected structure.

32. A liquid crystal light modulation element according to claim 31, wherein

said projected structure has a rib-like form.

33. A liquid crystal light modulation element according to claim 31, wherein

said projected structure has a side surface inclined with respect to a direction of a substrate normal.

34. A liquid crystal light modulation element according to claim 31, wherein

an electrode is formed on a surface of each of said substrates, and said projected structure is formed on the electrode of at least one of the substrates.

35. A liquid crystal light modulation element according to claim 31, wherein

a height h of said projected structure and a gap d between said substrates satisfy a relationship of d/20<

h<

d/2.

36. A liquid crystal light modulation element according to claim 31, wherein

a width W of said projected structure and a helical pitch p of the liquid crystal molecules satisfy a relationship of p<

W<

20p.

37. A liquid crystal light modulation element according to claim 31, wherein

an arrangement pitch L of said projected structures and a helical pitch p of the liquid crystal molecules satisfy a relationship of 5p<

L<

100p.

38. A liquid crystal light modulation element according to claim 37, wherein

said arrangement pitch L of said projected structures is not uniform within a range satisfying said relationship.

39. A liquid crystal light modulation element according to claim 31, comprising:

a plurality of pixels arranged in a direction different from a direction of arrangement of said projected structures.

40. A liquid crystal light modulation element according to claim 31, comprising:

a plurality of regions which are different in a direction of arrangement of said projected structures.

41. A liquid crystal light modulation element according to claim 30, wherein

an electrode is formed on each of said substrates and the orientation regulating means is a groove formed on the electrode on at least one of the substrates, and the anisotropy is caused in the directions of the lines of electric force of said electric field by the groove.

42. A liquid crystal light modulation element according to claim 41, wherein

a width W of said groove and a helical pitch p of the liquid crystal molecules satisfy a relationship of p<

W<

20p.

43. A liquid crystal light modulation element according to claim 41, wherein

an arrangement pitch L of said grooves and a helical pitch p of the liquid crystal molecules satisfy a relationship of 5p<

L<

100p.

44. A liquid crystal light modulation element according to claim 43, wherein

said arrangement pitch L of said grooves is not uniform within a range satisfying said relationship.

45. A liquid crystal light modulation element according to claim 41, comprising:

a plurality of pixels arranged in a direction different from a direction of arrangement of said grooves.

46. A liquid crystal light modulation element according to claim 41, comprising:

a plurality of regions which are different in a direction of arrangement of said grooves.

47. A liquid crystal light modulation element according to claim 30, wherein

an insulating film is formed on at least one of the substrates and the orientation regulating means is a groove formed on the insulating film, and the anisotropy is caused in the directions of the lines of electric force of the electric field by the groove.

48. A liquid crystal light modulation element according to claim 47, wherein

a width W of said groove and a helical pitch p of the liquid crystal molecules satisfy a relationship of p<

W<

20p.

49. A liquid crystal light modulation element according to claim 47, wherein

an arrangement pitch L of said grooves and a helical pitch p of the liquid crystal molecules satisfy a relationship of 5p<

L<

100p.

50. A liquid crystal light modulation element according to claim 49, wherein

said arrangement pitch L of said grooves is not uniform within a range satisfying said relationship.