Chiral smectic C or H liquid crystal electro-optical device
First Claim
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1. A liquid crystal electro-optical device comprising:
- a quantity of chiral, at least one of smectic C and smectic H, liquid crystal having a plurality of adjacently disposed layers each comprised of a plurality of molecules, each molecule having a long axis;
first and second means, perpendicular to and contiguous with said layers, for aligning the long axes of said molecules adjacent to said first and second means parallel to said first and second means, said molecules of said layers in a bulk of said liquid crystal forming helixes having axes perpendicular to said layers, the distance between said first and second means being less than the distance at which said helixes form in the absence of an electric field, said first and second means causing said long axes to assume one of a first and second stable orientation;
means for applying an electric field to at least a portion of said layers, said electric field being parallel to said layers and perpendicular to said first and second means, and for reversing the direction of said electric field, the strength of said electric field being sufficient to shift the long axis of molecules in said portion of said layers from said first orientation to said second orientation upon application of said electric field in a direction reversed from the direction of said electric field previously applied; and
means for processing light passing through said liquid crytstal so that light passing through portions of said liquid crystal having said first orientation can be distinguished from light passing through portions of said liquid crystal having said second orientation.
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Abstract
An electro-optical device including a chiral smectic C or H liquid crystal disposed between flat plates treated to enforce molecular orientation parallel to the plates. The plates are spaced by a distance sufficiently small to ensure unwinding of the helix typical in a bulk of the material to form two stable states of the orientation field. The liquid crystal is switched between two stable states by reversing the polarity of an externally applied electric field to make a bistable light valve or other electro-optical devices.
505 Citations
24 Claims
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1. A liquid crystal electro-optical device comprising:
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a quantity of chiral, at least one of smectic C and smectic H, liquid crystal having a plurality of adjacently disposed layers each comprised of a plurality of molecules, each molecule having a long axis; first and second means, perpendicular to and contiguous with said layers, for aligning the long axes of said molecules adjacent to said first and second means parallel to said first and second means, said molecules of said layers in a bulk of said liquid crystal forming helixes having axes perpendicular to said layers, the distance between said first and second means being less than the distance at which said helixes form in the absence of an electric field, said first and second means causing said long axes to assume one of a first and second stable orientation; means for applying an electric field to at least a portion of said layers, said electric field being parallel to said layers and perpendicular to said first and second means, and for reversing the direction of said electric field, the strength of said electric field being sufficient to shift the long axis of molecules in said portion of said layers from said first orientation to said second orientation upon application of said electric field in a direction reversed from the direction of said electric field previously applied; and means for processing light passing through said liquid crytstal so that light passing through portions of said liquid crystal having said first orientation can be distinguished from light passing through portions of said liquid crystal having said second orientation. - View Dependent Claims (3, 4, 5, 6, 7, 10, 11, 16, 22, 23)
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2. A liquid crystal electro-optical device comprising:
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a quantity of chiral, at least one of smectic C and smectic H, liquid crystal, said liquid crystal having a plurality of adjacently disposed layers each comprised of a plurality of molecules, each molecule having a long axis; first and second means, perpendicular to and contiguous with said layers, for aligning said long axis of molecules adjacent to said first and second means parallel to said first and second means, said molecules of said layers in a bulk of said liquid crystal forming helixes having axes perpendicular to said layers, the distance between said first and second means being less than the distance at which said helixes form in the absence of an electric field, said first and second means causing said long axes to assume one of a first and second stable orientation; means for selectively applying an electric field to any of a plurality of portions of said layers, said electric field being parallel to said layers and perpendicular to said first and second means, and for reversing the direction of said electric field, the strength of said electric field being sufficient to shift molecules in said any of a plurality of portions from said first orientation to said second orientation upon application of said electric field in a direction reversed from the direction of said electric field previously applied; and means for processing light passing through said liquid crystal so that light passing through portions of said liquid crystal having said first orientation can be distinguished from light passing through portions of said liquid crystal having said second orientation. - View Dependent Claims (12)
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8. A liquid crystal electro-optical device comprising:
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a quantity of chiral, at least one of smectic C and smectic H, liquid crystal having a plurality of adjacently disposed layers, each comprised of a plurality of molecules, each molecule having a long axis; first and second plates perpendicular to said layers, said first and second plates including means, contiguous with said liquid crystal for aligning the long axis of said molecules adjacent to said aligning means parallel to said plates, said molecules of said layers in a bulk of said liquid crystal forming helixes having axes perpendicular to said layers, the distance between said first plate and said second plate being less than the distance at which said helixes form in the absence of an electric field; a first electrode disposed on one side of said liquid crystal parallel to said first and second plates; a second electrode disposed on the other side of said liquid crystal parallel to said first and second plates and opposite said first electrode; means for applying a voltage across said first and second electrodes for creating an electric field parallel to said layers and perpendicular to said plates, and for reversing the polarity of said voltage, said voltage being such that the strength of said electric field is sufficient to shift the long axis of molecules in a portion of said layers between said electrodes from a first orientation to a second orientation upon application of said electric field in a direction reversed from the direction of said electric field previously applied; and means for processing light passing through said liquid crystal so that light passing through portions of said liquid crystal having said first orientation can be distinguished from light passing through portions of said liquid crystal having said second orientation. - View Dependent Claims (13, 14, 15)
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9. A liquid crystal electro-optical device comprising:
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a quantity of chiral, at least one of smectic C and smectic H, liquid crystal having a plurality of adjacently disposed layers, each comprised of a plurality of molecules, each molecule having a long axis; first and second plates perpendicular to said layers, said first and second plates including means, contiguous with said liquid crystal, for aligning the long axis of said molecules adjacent to said aligning means parallel to said plates, said molecules of said layers in a bulk of said liquid crystal forming helixes having axes perpendicular to said layers, the distance between said first plate and said second plate being less than the distance at which said helixes form in the absence of an electric field; a plurality of first electrodes disposed on one side of said liquid crystal parallel to said first and second plates; a plurality of second electrodes disposed on the other side of said liquid crystal parallel to said first and second plates and transverse to said first electrodes; means for selectively applying a voltage across any of said first electrodes and any of said second electrodes for creating an electric field in any of a plurality of portions of said liquid crystal parallel to said layers and perpendicular to said plates, and for reversing the polarity of said voltage, said voltage being such that the strength of said electric field is sufficient to shift the long axis of molecules in said any of a plurality of portions from a first orientation to a second orientation upon application of said electric field in a direction reversed from the direction of said electric field previously applied; and means for processing light passing through said liquid crystal so that light passing through portions of said liquid crystal having said first orientation can be distinguished from light passing through portions of said liquid crystal having said second orientation.
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17. A process of making an electro-optical device including a chiral, at least one of smectic C and smectic H, liquid crystal, molecules in a bulk of said liquid crystal forming helixes, first and second means for containing said liquid crystal, means for applying an electric field to at least a portion of said liquid crystal and means for processing light passing through said liquid crystal, said method comprising:
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aligning the molecules of said liquid crystal adjacent to said first and second means parallel to said first and second means, but free to move between at least two particular orientations; and suppressing the formation of said helixes.
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18. A process of making an electro-optical device including a chiral, at least one of smectic C or smectic H, liquid crystal, molecules in a bulk of said liquid crystal forming helixes, first and second means for containing said liquid crystal, means for applying an electric field to at least a portion of said liquid crystal and means for processing light passing through said liquid crystal, said method comprising:
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disposing said first means a distance from said second means less than the distance at which said helixes form; first cooling said liquid crystal from at least one of an isotropic and nematic phases; aligning the molecules of said liquid crystal adjacent to said first and second means parallel to said first and second means, but free to move between at least two particular orientations; and orienting said liquid crystal during said first cooling step to form at least one of smectic C and smectic H phases in flat layers perpendicular to said first and second means. - View Dependent Claims (20, 21)
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19. A process of making an electro-optical device including a chiral, at least one of smectic C or smectic H, liquid crystal, molecules in a bulk of said liquid crystal forming helixes, first and second means for containing said liquid crystal, means for applying an electric field to at least a portion of said liquid crystal and means for processing light passing through said liquid crystal, said method comprising:
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disposing said first means a distance from said second means less than the distance at which said helixes form; first cooling said liquid crystal from at least one of an isotropic and nematic phases to a smectic A phase; aligning the molecules of said liquid crystal adjacent to said first and second means parallel to said first and second means, but free to move between at least two particular orientations; orienting said liquid crystal during said first cooling step to form said smectic A liquid crystal in flat layers perpendicular to said first and second means; and second cooling of said liquid crystal from said smectic A phase to said at least one of smectic C and smectic H phases. - View Dependent Claims (24)
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Specification