EP0212928A2
Expired / Lapsed
EP
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Thermal imaging device
Assignee: The General Electric Company PLC
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Filing: 1986-08-07
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Granted: —
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Expires: 2006-08-07
Abstract
Abstract A thermal imaging device uses a compensated cholesteric liquid crystal mixture (1) as its thermooptic conversion element. The mixture is obtained by mixing two cholesteric liquid crystals, one with a left-handed twist and the other with a right-handed twist. The twists cancel at a compensation temperature (T N ) the mixture thus having infinite twist at this temperature. The device is designed to operate with the mixture (1) held in the region of the compensation temperature (T N ).
Inventors
- 👤 Cyril Hilsum
- 👤 Martin Rhodri Lewis
- 👤 Michael Charles Keogh Wiltshire
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-03 22:40
CPC Classifications
G; G02; G02F; G02F1/00; G02F1/01; G02F1/13; G02F1/132; C; C09; C09K; C09K19/00; C09K19/02
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
81 words
A thermal imaging device characterised in that it includes as its thermo-optic conversion element a compensated cholesteric liquid crystal (1) obtained by mixing two cholesteric liquid crystals, one with a left-handed twist, and the other with a right-handed twist, the mixture having a composition such that the twists cancel at a compensation temperature the mixture thus having infinite pitch at the compensation temperature, the imaging device being designed to operate with the mixture held in the region of the compensation temperature.
Claim 2
Dependent Claim
81 words
A thermal imaging device characterised in that it includes as its thermo-optic conversion element a compensated cholesteric liquid crystal (1) obtained by mixing two cholesteric liquid crystals, one with a left-handed twist, and the other with a right-handed twist, the mixture having a composition such that the twists cancel at a compensation temperature the mixture thus having infinite pitch at the compensation temperature, the imaging device being designed to operate with the mixture held in the region of the compensation temperature.
Claim 3
Dependent Claim
24 words
A device according to Claim 1 in which one of the cholesteric liquid crystals is near a smectic phase change at the compensation temperature.
Claim 4
Independent Claim
50 words
A device according to either one of the preceding claims in which the liquid crystal mixture is confined between two surfaces (3,5) the alignment of the liquid crystal mixture being planar adjacent to one (3) of the two surfaces, and homeotropic adjacent to the other (5) of the two surfaces.
Claim 5
Dependent Claim
25 words
A device according to Claim 3 in which the homeotropic alignment is produced by a layer (15) of a surfactant on said other surface (5).
Claim 6
Dependent Claim
14 words
A device according to Claim 4 in which the surfactant is an organosilane octadecyl-triethoxysilane.
Claim 7
Independent Claim
25 words
A device according to any one of Claims 3 to 5 in which the planar alignment is produced by a unidirectionally rubbing said one surface.
Claim 8
Independent Claim
20 words
A device according to any one of Claims 3 to 5 in which said one surface (13) is a polymer.
Claim 9
Independent Claim
34 words
A device according to any one of the preceding claims in which one of said two cholesteric liquid crystals is cholesteryl myristate, and the other of said two cholesteric liquid crystals is cholesteryl chloride.
Claim 10
Independent Claim
39 words
A device according to any one of Claims 1 to 7 in which said mixture is a mixture of two biphenyl chiral dopants in a nematic host, the two dopants inducing reverse twists to each other in the host.
Claim 11
Dependent Claim
14 words
10 A device according to Claim 9 in which the two dopants are and
Claim 12
Independent Claim
30 words
A device according to any one of Claims 1 to 7 in which the mixture comprises CB15 produced by BDH and S811 produced by Merck in ZLI1132 produced by Merck.
Claim 13
Independent Claim
39 words
A device according to any one of the preceding claims in which means are provided for maintaining the mixture at a temperature just off the compensation temperature so as to avoid ambiguity in the output signal of the device.
Claim 14
Independent Claim
48 words
A device according to any one of Claims 1 to 11 in which a chopper is arranged to chop infra-red radiation incident on the device, and means are provided for maintaining the mixture at its compensation temperature while the chopper is blocking the incident radiation from the device.
References Cited (Backward Citations)
No citation records indexed.
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