US4639090A
Expired / Lapsed
US
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Liquid crystal dichroic display with a high brightness contrast
Assignee: Commissariat à l'Énergie Atomique et Aux Énergies Alternatives
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Filing: 1985-05-22
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Granted: 1987-01-27
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Expires: 2005-05-22
Abstract
Abstract The display comprises a cholesteric liquid crystal film in which are embedded dye molecules between the two walls separated by a shim. One wall is at least partly covered by a reflecting coating reversing the polarization of a circularly polarized electromagnetic wave. The optical anisotropy Δn and the helix pitch p are such that the least absorbed wave on passing through the cell has an ellipticity equal to or greater than π/8.
Inventors
- 👤 Jean-Frederic Clerc
- 👤 Francis Muller
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 00:33
CPC Classifications
G; G02; G02F; G02F1/00; G02F1/01; G02F1/13; G02F1/137; G02F1/13731; G02F1/13737; G02F2201/00; G02F2201/12; G02F2201/121; G02F2203/00; G02F2203/02
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
112 words
A liquid crystal dichroic display with a high brightness contrast, comprising a liquid crystal film between two walls separated by a shim, one wall carrying transparent electrodes and the other wall a counterelectrode, said liquid crystal film having an optical anisotropy Δn and, in the absence of an electric field, a twisted or helical structure of pitch p, the wall carrying the counterelectrode being at least partly covered with a reflecting coating reversing the polarization of a circularly polarized electromagnetic wave and the optical anisotropy Δn and the pitch p being such that the light wave absorbed least by the display used in transmission has an ellipticity at least equal to π/8.
Claim 2
Dependent Claim
112 words
A liquid crystal dichroic display with a high brightness contrast, comprising a liquid crystal film between two walls separated by a shim, one wall carrying transparent electrodes and the other wall a counterelectrode, said liquid crystal film having an optical anisotropy Δn and, in the absence of an electric field, a twisted or helical structure of pitch p, the wall carrying the counterelectrode being at least partly covered with a reflecting coating reversing the polarization of a circularly polarized electromagnetic wave and the optical anisotropy Δn and the pitch p being such that the light wave absorbed least by the display used in transmission has an ellipticity at least equal to π/8.
Claim 3
Dependent Claim
16 words
A dichroic display according to claim 1, wherein the reflecting coating is constituted by the counterelectrode.
Claim 4
Dependent Claim
26 words
A dichroic display according to claim 1, wherein the liquid crystal film comprises a mixture of a nematic liquid crystal, dye molecules and a chiral compound.
Claim 5
Dependent Claim
16 words
A dichroic display according to claim 3, wherein the chiral compound is a cholesteric liquid crystal.
Claim 6
Dependent Claim
16 words
A dichroic display according to claim 3, wherein the dye molecules comprise anthroquinones or azo compounds.
Claim 7
Dependent Claim
20 words
A dichroic display according to claim 3, wherein at least one of the liquid crystals comprises phenylcyclohexane, biphenylcyclohexane and cyclohexylcyclohexane.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1990-01-26 | 1990-07-28 | 1991-01-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-01-26 | 1994-07-28 | 1995-01-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-01-26 | 1998-07-28 | 1999-01-27 | $7700.00 | Window Closed / Lapsed |