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US4852978A
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Liquid crystal cell utilizing a ferroelectric liquid crystal having a natural pitch length is no longer than the longest wavelength of visible light
Assignee: Nortel Networks Ltd
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Filing: 1987-06-23
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Granted: 1989-08-01
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Expires: 2007-06-23
Abstract
Abstract Bistable switching between clear and scattering states is provided by a liquid crystal cell whose liquid crystal layer is constituted by a random orientation planar aligned ferroelectric smectic exhibiting a pitch length comparable with the wavelength of visible light.
Inventors
- 👤 Anthony B. Davey
- 👤 Matthew F. Bone
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 14:07
CPC Classifications
G; G02; G02F; G02F1/00; G02F1/01; G02F1/13; G02F1/137; G02F1/139; G02F1/141; C; C09; C09K; C09K19/00; C09K19/04; C09K19/06; C09K19/08; C09K19/10; C09K19/20; C09K19/2007; C09K19/2021; G02F1/13756
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
88 words
A liquid crystal cell switchable between an optically clear state that is stable, or is quasi-stable having a relaxation period in excess of one second, and an optically scattering stable state, wherein the active medium of said cell is provided by a layer of ferroelectric liquid crystal material whose natural pitch length is in the range defined by the wavelength range of visible light, which layer is confined by surfaces that promote planar alignment of the liquid crystal molecules at the major surfaces of the liquid crystal layer.
Claim 2
Dependent Claim
88 words
A liquid crystal cell switchable between an optically clear state that is stable, or is quasi-stable having a relaxation period in excess of one second, and an optically scattering stable state, wherein the active medium of said cell is provided by a layer of ferroelectric liquid crystal material whose natural pitch length is in the range defined by the wavelength range of visible light, which layer is confined by surfaces that promote planar alignment of the liquid crystal molecules at the major surfaces of the liquid crystal layer.
Claim 3
Dependent Claim
27 words
A liquid crystal cell as claimed in claim 1, wherein the surfaces that confine the liquid crystal layer promote randomly oriented planar alignment at its major surfaces.
Claim 4
Dependent Claim
30 words
A liquid crystal cell as claimed in claim 1 wherein the thickness of the liquid crystal layer is greater than the natural pitch length of the material of that layer.
Claim 5
Dependent Claim
27 words
A liquid crystal cell as claimed in claim 3 wherein the surfaces that confine the liquid crystal layer promote randomly oriented planar alignment at its major surfaces.
Claim 6
Dependent Claim
86 words
A liquid crystal cell switchable between an optically clear state that is stable, or is quasi-stable having a relaxation period in excess of 1 second, and an optically scattering stable state, wherein the active medium of said cell is provided by a layer of ferroelectric liquid crystal material whose natural pitch length is no longer than the longest wavelength of visible light, which layer is confined by surfaces that promote planar alignment of the liquid crystal molecules at the major surfaces of the liquid crystal layer.
Claim 7
Dependent Claim
86 words
A liquid crystal cell switchable between an optically clear state that is stable, or is quasi-stable having a relaxation period in excess of 1 second, and an optically scattering stable state, wherein the active medium of said cell is provided by a layer of ferroelectric liquid crystal material whose natural pitch length is no longer than the longest wavelength of visible light, which layer is confined by surfaces that promote planar alignment of the liquid crystal molecules at the major surfaces of the liquid crystal layer.
Claim 8
Dependent Claim
27 words
A liquid crystal cell as claimed in claim 5 wherein the surfaces that confine the liquid crystal layer promote randomly oriented planar alignment at its major surfaces.
Claim 9
Dependent Claim
30 words
A liquid crystal cell as claimed in claim 6 wherein the thickness of the liquid crystal layer is greater than the natural pitch length of the material of that layer.
Claim 10
Dependent Claim
27 words
A liquid crystal cell as claimed in claim 7 wherein the surfaces that confine the liquid crystal layer promote randomly oriented planar alignment at its major surfaces.
References Cited (Backward Citations)
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US4702558A
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GB2166256A
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WO1986002938A1
Cited
US4744639A
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1992-07-31 | 1993-01-30 | 1993-08-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-07-31 | 1997-01-30 | 1997-08-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-07-31 | 2001-01-30 | 2001-08-01 | $7700.00 | Window Closed / Lapsed |