Encapsulated liquid crystal material, apparatus and method

• US 5,082,351 A
• Filed: 04/14/1989
• Issued: 01/21/1992
• 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): Zazworsky, John
• Assistant Examiner(s): GROSS, ANITA P
• Application Number:
  US07/339,072
• Time in Patent Office: 1,012 Days
• Field of Search: 350/334, 350/336, 350/339 R, 350/338, 350/340, 350/347 V, 29/592.1
• 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 2202/043 pleochroic

Abstract

A liquid crystal apparatus includes a plurality of volumes of liquid crystal material in a containment medium such as an epoxy or polymer. The volumes of liquid crystal material can be 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 material 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. Pleochroic dye in the liquid crystal material increases absorption of incident light. 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, including a method of applying an electrode using optically reflective particulate material with a binder medium.

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, reflector means for reflecting light scattered by or transmitted through said liquid crystal material, 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 material as such input, said support means and said second electrode means being substantially optically transparent, said reflector means comprising said first electrode means, said first electrode means comprising electrically conductive, optically reflective ink, and said ink comprising silver flake dispersed in a solution of an electrically non-conductive, generally optically transparent binder medium.

2. The invention of claim 1, said binder medium comprising polyvinyl alcohol.

3. 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, pleochroic dye in said liquid crystal material for absorbing light incident thereon when such liquid crystal material is in non-parallel alignment, reflector means for reflecting light scattered by or transmitted through said liquid crystal material, 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 material as such input, said support means and said second electrode means being substantially optically transparent, said reflector means comprising said first electrode means, said first electrode means comprising electrically conductive, optically reflective ink, and said ink comprising silver flake dispersed in a solution of an electrically non-conductive, generally optically transparent binder medium.

4. The invention of claim 3, said binder medium comprising polyvinyl alcohol.

5. 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, said liquid crystal material having positive dielectric anisotropy, and 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, reflector means for reflecting light scattered by or transmitted through said liquid crystal material, 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 material as such input, said support means and said second electrode means being substantially optically transparent, said reflector means comprising said first electrode means, said first electrode means comprising electrically conductive, optically reflective ink, and said ink comprising silver flake dispersed in a solution of an electrically non-conductive, generally optically transparent binder medium.

6. The invention of claim 5, said binder medium comprising polyvinyl alcohol.

7. Liquid crystal apparatus, comprising liquid crystal material and containment means for inducing a distorted alignment of said liquid crystal material and which apparatus in response to such alignment at least one of scatters or absorbs light and in response to a prescribed input reduces the amount of such scattering or absorption, and wherein said containment means comprises a compound selected from the group consisting of cyanoethyl cellulose, acrylonitrile butadiene rubbers, phenolics, polyvinyl fluoride, phenol formaldehyde, cellulose acetate, polvinyl chloride, urethane elastomers, cellulose nitrate, regenerated cellulose, chlorosulphonated polyethylene, polyacrylonitrile, cellulose acetate butyrate, Nylon, polyester, urea formaldehyde, alkyd, and a mixture of two or more thereof.

8. The subject matter of claim 7, wherein said liquid crystal exhibits positive dielectric anisotropy.

9. Liquid crystal apparatus, comprising liquid crystal material and containment means for inducing a distorted alignment of said liquid crystal material and which apparatus in response to such alignment at least one of scatters or absorbs light and in response to a prescribed input reduces the amount of such scattering or absorption, and wherein said containment means comprises a polymer;

and

wherein said liquid crystal exhibits positive dielectric anisotropy.

10. Liquid crystal apparatus, comprising liquid crystal material and containment means for inducing a distorted alignment of said liquid crystal material and which apparatus in response to such alignment at least one of scatters or absorbs light and in response to a prescribed input reduces the amount of such scattering or absorption, and wherein said containment means comprises epoxy.

11. The subject matter of claim 10, wherein said liquid crystal exhibits positive dielectric anisotropy.

12. A liquid crystal apparatus, comprising a plurality of volumes of liquid crystal material assembled in a medium, said assemblage of volumes of liquid crystal and medium characterized in having combined resistivity to allow an electric field to be impressed thereacross, said liquid crystal characterized in having positive dielectric anisotropy and being operative to align with respect to such an applied electric field and further characterized to undergo alignment due to surface interaction with said medium in the absence of such an electric field, and the apparatus being further characterized in providing an optical response to an applied electric field by matching ordinary index of refraction of the liquid crystal with the index of refraction of the medium;

and

wherein said medium comprises a compound selected from the group consisting of cyanoethyl cellulose, acrylonitrile butadiene rubbers, phenolics, polyvinyl alcohol, polyvinyl fluoride, phenol formaldehyde, cellulose acetate, polyvinyl chloride, urethane elastomers, cellulose nitrate, regenerated cellulose, chlorosulphonated polyethylene, polyacrylonitrile, cellulose acetate butyrate, Nylon, polyester, urea formaldehyde, alkyd, and a mixture of two or more thereof.

13. A liquid crystal apparatus, comprising a plurality of volumes of liquid crystal material assembled in a medium, said assemblage of volumes of liquid crystal and medium characterized in having combined resistivity to allow an electric field to be impressed thereacross, said liquid crystal characterized in having positive dielectric anisotropy and being operative to align with respect to such an applied electric field and further characterized to undergo alignment due to surface interaction with said medium in the absence of such an electric field, and the apparatus being further characterized in providing an optical response to an applied electric field by matching ordinary index of refraction of the liquid crystal with the index of refraction of the medium;

and

wherein said medium comprises epoxy.

14. A liquid crystal apparatus, comprising a plurality of volumes of liquid crystal material assembled in a medium, said assemblage of volumes of liquid crystal and medium characterized in having electrical characteristics to allow an electric field to be impressed thereacross, said liquid crystal characterized in having positive dielectric anisotropy and being operative to align with respect to such an applied electric field and further characterized to undergo alignment due to surface interaction with said medium in the absence of such an electric field, pleochroic dye contained in the liquid crystal material, and the apparatus being further characterized in providing an optical response to an applied electric field by alignment of such pleochroic dye contained in the liquid crystal material.

15. The apparatus of claim 14, wherein said apparatus is further characterized in providing an optical response to an applied electric field by matching ordinary index of refraction of the liquid crystal with the index of refraction of the medium.

16. A liquid crystal apparatus, comprising a plurality of volumes of liquid crystal material assembled in a medium, said assemblage of volumes of liquid crystal and medium characterized in having electrical characteristics to allow an electric field to be impressed thereacross, said liquid crystal characterized in having positive dielectric anisotropy and being operative to align with respect to such an applied electric field and further characterized to undergo alignment due to surface interaction with said medium in the absence of such an electric field, and the apparatus being further characterized in providing an optical response to an applied electric field by matching ordinary index of refraction of the liquid crystal with the index of refraction of the medium;

and

wherein said medium comprises epoxy.

17. A liquid crystal apparatus, comprising a plurality of volumes of liquid crystal material assembled in a medium, said assemblage of volumes of liquid crystal and medium characterized in having electrical characteristics to allow an electric field to be impressed thereacross, said liquid crystal characterized in having positive dielectric anisotropy and being operative to align with respect to such an applied electric field and further characterized to undergo alignment due to surface interaction with said medium in the absence of such an electric field, and the apparatus being further characterized in providing an optical response to an applied electric field by matching ordinary index of refraction of the liquid crystal with the index of refraction of the medium;

and

wherein said medium comprises polymer.

18. A liquid crystal apparatus, comprising a plurality of volumes of liquid crystal material assembled in a medium, said assemblage of volumes of liquid crystal and medium characterized in having combined resistivity to allow an electric field to be impressed thereacross, said liquid crystal characterized in having positive dielectric anisotropy and being operative to align with respect to such an applied electric field and further characterized to undergo alignment due to surface interaction with said medium in the absence of such an electric field, the apparatus being further characterized in providing an optical response to an applied electric field by matching index of refraction characteristics and/or when the liquid crystal contains pleochroic dye by alignment of such pleochroic dye contained in the liquid crystal material, and

wherein said medium comprises epoxy.

19. A liquid crystal apparatus, comprising a plurality of volumes of liquid crystal material assembled in a medium, said assemblage of volumes of liquid crystal and medium characterized in having combined resistivity to allow an electric field to be impressed thereacross, said liquid crystal characterized in having positive dielectric anisotropy and being operative to align with respect to such an applied electric field and further characterized to undergo alignment due to surface interaction with said medium in the absence of such an electric field, the apparatus being further characterized in providing an optical response to an applied electric field by matching index of refraction characteristics and/or when the liquid crystal contains pleochroic dye by alignment of such pleochroic dye contained in the liquid crystal material,

wherein said plurality of volumes comprises a plurality of interconnected volumes, and

wherein said medium comprises epoxy.

20. A method of applying an electrode to liquid crystal material in a containment medium, comprising mixing electrically conductive optically reflective particulate material with a binder medium, and printing such mixture onto a surface of such liquid crystal material in a containment medium.

21. The method of claim 20, said mixing comprising mixing silver flake and polyvinyl alcohol.

22. The method of claim 20, said printing comprising silk screening.