Polymer-dispersed liquid crystal material with in-situ polymerized liquid crystal polymer grains dispersed in a layer of liquid crystal material sealed between substrates and field electrodes
First Claim
1. A method of fabricating a polymer dispersed liquid crystal display having a polymer dispersed liquid crystal medium formed in a gap portion in said display comprising the steps of:
- forming a mixture of liquid crystal material and thermoplastic polymer to cause said liquid crystal material and polymer to be soluble in one other;
injecting said soluble mixture in the gap portion,aligning the liquid crystal material and polymer in a predetermined direction while said mixture remains in its soluble state; and
causing said mixture to bring about a phase separation between the liquid crystal material and the polymer forming polymer grains dispersed throughout the liquid crystal material retaining their original alignment in said predetermined direction.
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Abstract
A polymer dispersed liquid crystal material (PDLC) device is fabricated by sealing a composite layer mixture of components comprising a polymer and liquid crystal material while both are in their liquid phase in a gap portion formed between two substrates of the device. A predetermined directional alignment is transmitted to the polymer via the liquid crystal material by means, for example, of formed directional alignment on surfaces in contact with the composite layer, such as, by deposited alignment films on a surface of at least one of the substrates. The predetermined directional alignment of the polymer is thereafter fixed by means of a polymer hardening method, such as, for example, by polymerization of a polymer precursor, so that the predetermined directional alignment of the polymer is permanently retain within the liquid crystal material, i.e., the polymer is in a solid phase and the liquid crystal material remains in its liquid phase. For better results, a chiral component and/or a light absorbing component may be added to the liquid crystal material.
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Citations
95 Claims
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1. A method of fabricating a polymer dispersed liquid crystal display having a polymer dispersed liquid crystal medium formed in a gap portion in said display comprising the steps of:
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forming a mixture of liquid crystal material and thermoplastic polymer to cause said liquid crystal material and polymer to be soluble in one other; injecting said soluble mixture in the gap portion, aligning the liquid crystal material and polymer in a predetermined direction while said mixture remains in its soluble state; and causing said mixture to bring about a phase separation between the liquid crystal material and the polymer forming polymer grains dispersed throughout the liquid crystal material retaining their original alignment in said predetermined direction. - View Dependent Claims (2)
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3. A method of fabricating a polymer dispersed liquid crystal display comprising the steps of:
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forming a mixture of liquid crystal material and polymer precursor to cause said liquid crystal material and polymer precursor to be soluble in one other in their liquid phases, aligning said liquid crystal material and polymer precursor in a predetermined direction while in their liquid phases; and polymerizing said polymer precursor in-situ to form a plurality of solid polymer grains dispersed throughout said liquid crystal material with a phase separation occurring between the liquid crystal material and the polymer grains wherein the polymer grains maintain said predetermined directional alignment. - View Dependent Claims (4, 5, 6)
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7. A method of fabricating a polymer dispersed liquid crystal display comprising the steps of:
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processing at least one inner surface of a pair of planar substrates having inner electrodes to align a liquid crystal material and a polymer precursor in contact therewith in a direction substantially parallel with or perpendicular to the plane of said substrates; forming a mixture of the liquid crystal material and polymer precursor into each other; sealing said mixture between said substrates; and polymerizing said polymer precursor in-situ to yield a polymer, such that a phase separation is exhibited between the liquid crystal material and polymer with the polymer retaining said alignment.
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8. A method of fabricating a polymer dispersed liquid crystal display comprising the steps of:
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processing a surface of a first substrate to enable a liquid crystal material and a polymer precursor to align in a common direction substantially parallel with or perpendicular to the plane of said substrate; forming a mixture of the liquid crystal material and the polymer precursor into each other to form a soluble liquid phase and coating said mixture onto said substrate; aligning the liquid crystal material and said polymer precursor in said common direction while in said soluble liquid phase; and polymerizing said polymer precursor to yield a polymer, so as to have a phase separation between the liquid crystal material and polymer which retains said common direction alignment. - View Dependent Claims (9, 10)
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11. A liquid crystal device made according to the process of:
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sealing in said device a mixture of a liquid crystal material and a polymer precursor while both are in their liquid phase; transmitting a predetermined direction of alignment to said polymer precursor through said liquid crystal material utilizing an alignment means; and solidifying the polymer precursor into a hardened polymer while causing the precipitation of said polymer from said mixture into a plurality of solid grains dispersed throughout said liquid crystal material such that said predetermined direction of alignment is permanently retained by said polymer grains. - View Dependent Claims (12, 13)
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- 14. A polymer dispersed liquid crystal device comprising a mixture of in-situ fixation of pre-aligned polymer grains dispersed in a layer of liquid crystal medium sealed by at least one substrate in contact with said mixture.
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21. An improved polymer dispersed liquid crystal device having a drive voltage requirement under five volts, the improvement comprising:
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a polymer precursor comprising a monomethacrylate and not a diacrylate; and a liquid crystal layer comprising a liquid crystal material having a cholesteric pitch in the range of about 30 μ
m to about 0.60 μ
m. - View Dependent Claims (22, 23, 24)
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25. A polymer dispersed liquid crystal device having a spatial gap portion formed between spaced electrodes formed on respective substrates, comprising:
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a liquid crystal phase in said gap portion, a polymer phase comprising a plurality of polymeric grains dispersed in said liquid crystal phase, said liquid crystal phase having positive or negative dielectric anisotropy, alignment means provided relative to at least one of said substrates for orienting optical axes of both said liquid crystal phase and said polymer phase in a predetermined direction relative to a surface of said electrodes, means to fix the orientation of said polymer phase in said predetermined direction, and means to apply a field between said electrodes to switch between two conditions comprising matching and mismatching of the optical axes of said liquid crystal phase relative to said fixed polymer phase so that in one condition a light transparent state is created and in another condition a light dispersion state is created. - View Dependent Claims (26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41)
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42. A polymer dispersed liquid crystal device having a spatial gap portion formed between spaced electrodes formed on respective substrates, comprising:
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a liquid crystal phase in said gap portion, a polymer phase comprising solid polymeric grains dispersed in said liquid crystal phase, optical axes of said liquid crystal phase and said polymer phase alignable in a common direction substantially parallel with a surface of said electrodes, means provided in said liquid crystal phase to provide a helical twist to said polymer phase extending through said gap portion in a direction transverse to said electrode surface, and means to apply a field between said electrodes to switch between two conditions comprising matching and mismatching of the optical axes of said liquid crystal phase relative to said polymer so that in one condition a light transparent state is created and in another condition a light dispersion state is created. - View Dependent Claims (43, 44, 45, 46, 47, 48, 49, 50, 51, 52)
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53. A polymer dispersed liquid crystal device having a light modulating material formed between spatially disposed electrodes, comprising:
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said light modulating material comprising a polymer phase and a liquid crystal phase, said polymer phase and a liquid crystal phase having optical axes alignable together in a predetermined direction, light absorption additive included in said liquid crystal phase to provide for light absorption when said optical axes are aligned in said predetermined direction, means to apply a field between said electrodes to switch between two conditions comprising alignment and misalignment of the optical axes of said liquid crystal phase relative to said polymer phase so that in one condition a light absorption state is created in said material and in another condition a light dispersion state is created in said material. - View Dependent Claims (54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68)
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69. A polymer dispersed liquid crystal device having a light modulating material formed between spatially disposed electrodes, comprising:
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said light modulating material comprising a polymer phase dispersed in a liquid crystal phase, said polymer phase and a liquid crystal phase having optical axes alignable together in a predetermined direction, means to apply a field between said electrodes to switch between two conditions comprising matching and mismatching of the optical axes of said liquid crystal phase relative to said polymer phase wherein in a field-OFF condition, incident light on said device is transparent in said material and wherein in a field-ON state, incident light on said device is absorbed and dispersed. - View Dependent Claims (70, 71, 72, 73, 74, 75, 76)
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77. A polymer dispersed liquid crystal device having a light modulating material formed between spatially disposed electrodes, comprising:
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said light modulating material comprising a polymer phase and a liquid crystal phase, said polymer phase and a liquid crystal phase having optical axes alignable together in a direction substantially perpendicular to a planar extent of said electrodes, light absorption additive included in said liquid crystal phase to provide for light absorption and scattering when said optical axes are nonaligned in said direction, means to apply a field between said electrodes to switch between two conditions comprising matching and mismatching of the optical axes of said liquid crystal phase relative to said polymer phase wherein in a field-OFF condition, said polymer phase and a liquid crystal phase optical axes are aligned and incident light on said device is transparent in said material and wherein in a field-ON state, said polymer phase and a liquid crystal phase optical axes are misaligned and incident light on said device is absorbed and scattered. - View Dependent Claims (78, 79, 80, 81, 82, 83, 84)
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85. A light modulating liquid crystal layer comprising
a birefringent, polymer, solid phase having no liquid crystal characteristics dispersed in a birefringent, liquid crystal phase, optical axes of said phases aligned relative to at least one surface of two surfaces between which the layer is maintained, ordinary and extraordinary indices of refraction of said phases being matched whereby the layer is transparent when the respective optical axes of said phases are in an aligned state, and the layer is opaque when the respective optical axes of said phases are in an unaligned state wherein said respective optical axes are substantially in orthogonal relation, said unaligned state occurring when an electric field is applied across said liquid crystal layer and said aligned state occurring in the absence said electric field across said liquid crystal layer.
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91. A light modulating liquid crystal layer comprising
a birefringent, liquid crystal or solid polymer dispersed in a birefringent, liquid crystal phase wherein said solid polymer, the ratio of said liquid crystal phase to said polymer being greater than 1: - 1,
a chiral type component additive included in said liquid crystal phase to provide a helical twist orientation to both said polymer and liquid crystal phase, means to fix the helical twist orientation of said polymer in said liquid crystal phase, optical axes of said liquid crystal phase and said polymer aligned relative to at least one surface of two surfaces between which the layer is maintained, ordinary and extraordinary indices of refraction of said liquid crystal phase and said polymer being matched whereby the layer is transparent when the optical axes of said liquid crystal phase and polymer are in an aligned state, and the layer is opaque when the optical axes of said liquid crystal phase and polymer are in unaligned state. - View Dependent Claims (92, 93)
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94. A light modulating liquid crystal material comprising:
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a birefringent, polymer, solid phase having no liquid crystal characteristics dispersed in a birefringent, liquid crystal phase, light absorption additive included in said liquid crystal phase, the effective indices of refraction of the polymer solid phase and the liquid crystal phase being matched for all directions of incident light so that the material is transparent in a field-OFF state, and the effective indices of refraction are mismatched in directions of incident light so that the material is light absorbing and scattering in a field-ON state.
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95. An improved polymer dispersed liquid crystal device having a drive voltage requirement under five volts, the improvement comprising:
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a polymer precursor comprising a monomethacrylate and not a diacrylate; and a liquid crystal layer comprising a liquid crystal material having a chiral component in the range of 0.1% to 5%.
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Specification