Encapsulated liquid crystal material, apparatus and method having interconnected capsules

• US 4,884,873 A
• Filed: 10/27/1987
• Issued: 12/05/1989
• Est. Priority Date: 09/16/1981
• Status: Expired due to Fees

• Current Assignee: Manchester R & D Partnership
• Original Assignee: Manchester R & D Partnership
• Inventors: Fergason, James L.
• Primary Examiner(s): NOT, DEFINED
• Assistant Examiner(s): Gallivan, Richard
• Application Number:
  US07/114,073
• Time in Patent Office: 770 Days
• Field of Search: 350/334, 350/336, 350/347 V, 350/349, 350/350 R, 252/299.01, 252/299.1, 252/299.5, 252/299.7, 428/1, 428/402.2, 428/402.21, 427/213.3, 427/213.35, 427/213.36
• US Class Current: 349/86
• CPC Class Codes: C09K 19/544 as dispersing or encapsulating medium around the liquid crystal
• CPC Class Codes: G02F 1/1334 based on polymer dispersed liquid crystals, e.g. microencapsulated liquid crystals
• CPC Class Codes: G02F 1/1335 Structural association of cells with optical devices, e.g. polarisers or reflectors
• CPC Class Codes: G02F 1/133524 Light-guides, e.g. fibre-optic bundles, louvered or jalousie light-guides
• CPC Class Codes: G02F 1/137 characterised by the electro-optical or magneto-optical effect, e.g. field-induced phase transition, orientation effect, guest-host interaction or dynamic scattering
• CPC Class Codes: G02F 2202/043 pleochroic
• CPC Class Codes: Y10T 428/249997 Encapsulated liquid
• CPC Class Codes: Y10T 428/2984 Microcapsule with fluid core [includes liposome]
• CPC Class Codes: Y10T 428/2985 Solid-walled microcapsule from synthetic polymer

Abstract

A liquid crystal apparatus includes a plurality of volumes of liquid crystal material in a containment medium. At least some of the volumes are interconnected. The walls defining the volumes tend to distort the natural liquid crystal structure in the absence of an electric field, and the optical and electrical properties of the materials are such that in the absence of a field incident light is scattered or absorbed and in the presence of a field, scattering and/or absorption are reduced. The apparatus may be used in an optical display, optical shutter, billboard, etc., and it functions independently of polarization. Methods of making and using the apparatus also are included in the invention.

Claims

1. Liquid crystal apparatus, comprising liquid crystal material, containment means for inducing a generally non-parallel alignment of said liquid crystal material which in response to such alignment at least one of scatters and absorbs light and which in response to a prescribed input reduces the amount of such scattering or absorption, and reflector means for reflecting light scattered by or transmitted through said liquid crystal material.

2. The invention of claim 1, further comprising pleochroic dye in said liquid crystal material for absorbing light incident thereon when such liquid crystal material is in non-parallel alignment.

3. The invention of claim 1, said liquid crystal material having positive dielectric anisotropy, an ordinary index of refraction substantially matched to the index of refraction of such containment means to maximize transmission in the presence of such input and an extraordinary index of refraction different from that of said containment means to increase scattering in the absence of such input.

4. The invention of claims 1, 2 or 3, further comprising support means for supporting said liquid crystal material and containment means, a first electrode means at one side of said liquid crystal material and containment means remote from said support means, and a second electrode means between said support means and said liquid crystal material and containment means, said electrode means being positioned to apply electric field to said liquid crystal as such input.

5. The invention of claim 4, said first electrode means being substantially optically transparent, and said reflector means comprising said second electrode.

6. The invention of claim 4, said first electrode being substantially optically transparent, and said reflector means comprising a reflector on said support means.

7. The invention of claim 4, said first electrode means being substantially optically transparent, and said reflector means comprising said support means.

8. The invention of claim 7, said support means having a total internal reflection characteristic.

9. The invention of claim 4, said support means and said second electrode means being substantially optically transparent, and said reflector means comprising said first electrode means.

10. The invention of claim 9, said first electrode means comprising electrically conductive, optically reflective ink.

11. The invention of claim 4, wherein at least one of said electrode means is a patterned electrode having plural selectively energizable electrode portions to apply electric field to such liquid crystal material.

12. The invention of claim 11, wherein said first electrode means is said patterned electroded means, and further comprising electrical connection means for directly electrically connecting a source of electric energy to respective portions of said first electrode means to apply or not to apply electric field as such prescribed input to such liquid crystal material.

13. The invention of claim 12, wherein said liquid crystal material and containment means containing same are positioned in a prescribed pattern for support by said support means covering less than the entire support means.

14. The invention of claim 12, further comprising a protective layer of electrically non-conductive material over said first electrode means to protect same from external environment.

15. The invention of claim 4, wherein said liquid crystal material and containment means containing same are positioned in a prescribed pattern for support by said support means covering less than the entire support means.

16. The invention of claim 15, wherein at least one of said electrode means is a patterned electrode having plural selectively energizable electrode portions to apply electric field to such liquid crystal material.

17. The invention of claim 4, said containment means including a plurality of volumes containing said liquid crystal material.

18. The invention of claim 17, further comprising connecting means for fluidically connecting respective volumes.

19. The invention of claim 18, wherein in the absence of a prescribed input said liquid crystal material proximate a wall of such containment means tends to have the structure of said liquid crystal material aligned generally normal to such wall.

20. The invention of claim 18, wherein in the absence of a prescribed input said liquid crystal material proximate a wall of such containment means tends to have the structure of said liquid crystal material aligned generally parallel to such wall.

21. The invention of claim 20, wherein such prescribed input is an electric field and such liquid crystal structure tends to align parallel to such field in the presence thereof.

22. The invention of claim 20, wherein such prescribed input is an electric field and such liquid crystal structure tends to align parallel to such field in the presence thereof.

28. The invention of claim 22, wherein the dielectric constant of said medium is greater than the ordinary dielectric coefficient of such material.

29. The invention of claim 28, said containment means including a plurality of volumes containing said liquid crystal material.

30. The invention of claim 29, further comprising connecting means for fluidically connecting respective volumes.

23. Liquid crystal apparatus, comprising liquid crystal material, and containment means for inducing a generally non-parallel alignment of said liquid crystal material which in response to such alignment at least one of scatters and absorbs light and which in response to a prescribed input reduces the amount of such scattering or absorption, said containment means forming capsule-like volumes for containing said liquid crystal material, said volumes being of a diameter of from about 1 microns to about 5 microns.

24. Liquid crystal material and a medium means for containing discrete quantities of such liquid crystal material, said material having positive dielectric anisotropy, and wherein the difference between the ordinary index of refraction of said liquid crystal material and the index of refraction of said medium means being no greater than 0.07.

25. The invention of claim 24, said containment means including a plurality of volumes containing said liquid crystal material.

26. The invention of claim 25, further comprising connecting means for fluidically connecting respective volumes.

27. Liquid crystal material and a medium for forming volumes containing quantities of such liquid crystal material, said material having positive dielectric anisotropy, said medium having a dielectric constant that is no less than the lower dielectric coefficient value of said material, and wherein the electrical impedance taken along a path length through said medium alone is greater or equal to the electrical impedance taken along an equivalent path length through both said material and medium.

31. Liquid crystal material and a medium for containing discrete quantities of such liquid crystal material in a plurality of interconnected volumes, said material having positive dielectric anisotropy, said liquid crystal material having an ordinary index of refraction substantially the same as the index of refraction of said medium.

32. Liquid crystal material and a medium for containing discrete quantities of such liquid crystal material in a plurality of interconnected volumes, said material having positive dielectric anisotropy, said liquid crystal material comprising nematic liquid crystal material, and said medium comprising means for aligning the liquid crystal material to achieve a substantially maximum absorption of light energy under a no field condition.

33. Liquid crystal material and a medium for containing discrete quantities of such liquid crystal material in a plurality of interconnected volumes, said material having positive dielectric anisotropy, said medium having a dielectric constant that is no less than the lower dielectric constant value of said material.

34. The combination of nematic liquid crystal material contained in a plurality of generally spherical capsule volumes of encapsulating medium, said encapsulating medium having a wall, and wherein the ordinary index of refraction of said liquid crystal material is approximately the same as the index of refraction of the encapsulating medium.

35. A liquid crystal device comprising liquid crystal material and containment means, said containment means forming a plurality of fluidically interconnected capsules each having a curved interior wall surface, said capsules containing said liquid crystal material;

which liquid crystal material in the absence of an applied electric field at least one of scatters or absorbs incident light independently of the polarization of said light, and which device in the presence of an applied electric field displays decreased scattering or absorption at least in the direction of the applied electric field, and wherein a plurality of capsules containing liquid crystal material are not fluidically interconnected to other capsules.

36. Liquid crystal apparatus, comprising nematic liquid crystal material having positive dielectric anisotropy, and a plurality of interconnected containment means with curved surfaces for inducing a generally non-parallel alignment of said liquid crystal material which in response to such alignment at least one of scatters and absorbs light when pleochroic dye is present in the liquid crystal material and which in response to a prescribed input reduces the amount of such scattering or absorption, and wherein a plurality of containment means containing said liquid crystal material are not interconnected to other containment means.

37. A method of making encapsulated nematic liquid crystals, comprising mixing at least an encapsulating medium and a nematic liquid crystal material, and further comprising causing such liquid crystal material to perform substantially independently of the optical polarization direction of incident light, including confining such liquid crystal material in a plurality of containment capsules formed by such encapsulating medium that cause distortion of the direction of the liquid crystal molecules when no electric field is applied thereto.

40. The invention of any of claims 37 to 39, wherein said confining also includes confining such dyed liquid crystal material in a plurality of volumes that are not interconnected to other volumes.

38. A method of causing nematic liquid crystal material to perform substantially independently of the optical polarization direction of incident light, comprising confining such nematic liquid crystal material in a plurality of interconnected capsules which cause distortion of the direction of the liquid crystal material.

39. A method of causing liquid crystal material to perform substantially independently of the optical polarization direction of incident light, comprising combining pleochroic dye with the liquid crystal material and confining such dyed liquid crystal material in a plurality of interconnected volumes in a confining medium which causes distortion of the liquid crystal material.

41. An encapsulated operationally nematic liquid crystal material, comprising

operationally nematic liquid crystal material,

containment medium means for containing said liquid crystal material in volumes, and

means for tending to orient at least some of the structure of said liquid crystal material generally normal to a wall of said containment medium means in the absence of an electric field.

42. A method for adjusting the orientation of an operationally nematic liquid crystal material at the wall of a containment medium, comprising:

adding to the liquid crystal material a species which tends to align such liquid crystal material in a direction generally normal to a wall of such containment medium.