Patent JPS51147924A successfully refreshed from Google Patents.
EP0050433A2
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EP
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Temperature indicating devices
Assignee: National Research Development Corp UK
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Filing: 1981-10-01
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Granted: —
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Expires: 2001-10-01
Abstract
Abstract A temperature indicating device comprising a series of liquid crystal cells each of which contains a liquid crystal material having a different composition, the composition varying from cell-to-cell, and each of which cells exhibits the grandjean state whereby temperature is indicated by iridescence of the cells, the cells being such that the liquid crystal material in each has a clearing point at a different selected temperature in a series of temperatures in a temperature range of interest and that each of the cells is such that its liquid crystal material does not revert immediately to the grandjean state on cooling from the isotropic liquid state characterised in that the cells have a construction such that the liquid crystal material of each cell undergoes, on cooling from the isotropic liquid state, the transition isotropic liquid state to focal conic state, without reverting immediately to the grandjean state. Preferably, the liquid crystal material of the cells in free of cholesteryl compounds and is formed by a mixture including one or more cyanobiphenyl compounds.
Inventors
- 👤 Cyril Hilsum
- 👤 Damien Gerard Mcdonnell
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-03 12:30
CPC Classifications
G; G01; G01K; G01K11/00; G01K11/12; G01K11/16; G01K11/165; G01K13/00; G01K13/20
Claims Analysis
Total Claims: 24
Claim 1
Independent Claim
146 words
A temperature indicating device comprising a series of liquid crystal cells each of which contains a liquid crystal material having a different composition, the compositions varying from cell-to-cell, and each of which cells exhibits the grandjean state whereby temperature is indicated by iridescence of the cells, the cells being such that the liquid crystal material in each has a clearing point at a different selected temperature in a series of temperatures in a temperature range of interest and that each of the cells is such that its liquid crystal material does not revert immediately to the grandjean state on cooling from the isotropic liquid state characterised in that the cells have a construction such that the liquid crystal material of each cell undergoes, on cooling from the isotropic liquid state, the transition isotropic liquid state to focal conic state, without reverting immediately to the grandjean state.
Claim 2
Dependent Claim
146 words
A temperature indicating device comprising a series of liquid crystal cells each of which contains a liquid crystal material having a different composition, the compositions varying from cell-to-cell, and each of which cells exhibits the grandjean state whereby temperature is indicated by iridescence of the cells, the cells being such that the liquid crystal material in each has a clearing point at a different selected temperature in a series of temperatures in a temperature range of interest and that each of the cells is such that its liquid crystal material does not revert immediately to the grandjean state on cooling from the isotropic liquid state characterised in that the cells have a construction such that the liquid crystal material of each cell undergoes, on cooling from the isotropic liquid state, the transition isotropic liquid state to focal conic state, without reverting immediately to the grandjean state.
Claim 3
Dependent Claim
51 words
A device as claimed in claim 1 and wherein each of the cells comprises a layer of liquid crystal material, having an average thickness of between 10µm and 100µm, contained between substrates at least one of which is transparent, the substrates being coated on their inner surfaces with an aligning material.
Claim 4
Dependent Claim
16 words
A device as claimed in claim 2 and wherein the substrates are of glass or plastics.
Claim 5
Dependent Claim
29 words
A device as claimed in claim 2 or claim 3 and wherein the aligning material on at least one of the substrates has been unidirectionally rubbed prior to assembly.
Claim 6
Dependent Claim
19 words
A device as claimed in claim 2, claim 3 or claim.4 and wherein the aligning material is polyvinyl alcohol.
Claim 7
Independent Claim
29 words
A device as claimed in any one of claims 2 to 5 and wherein the average thickness of the liquid crystal material in each cell is about 30 µm.
Claim 8
Independent Claim
25 words
A device as claimed in any one of the preceding claims and wherein the liquid crystal material of each cell is free of cholesteryl compounds.
Claim 9
Independent Claim
26 words
A device as claimed in any one of the preceding claims and wherein the liquid crystal material of each cell includes a liquid crystal cyanobiphenyl compound.
Claim 10
Dependent Claim
24 words
A device as claimed in claim 8 and wherein the liquid crystal material of each cell includes a mixture of liquid crystal cyanobiphenyl compounds.
Claim 11
Independent Claim
58 words
A device as claimed in any one of the preceding claims and wherein the liquid crystal material of each of the cells comprises a mixture of compounds which together exhibit a chiral mesophase, the relative proportions of the compounds in the mixture varying from cell-to-cell whereby the clearing points of the materials vary from cell-to-cell in the series.
Claim 12
Independent Claim
101 words
A device as claimed in any one of the preceding claims and wherein the composition of the liquid crystal material in each cell comprises a mixture of two optically active liquid crystal materials, each of which contains the same given optically active liquid crystal compound but in different concentrations whereby the two materials selectively reflect light of the same colour in the grandjean state, at temperatures below their respective clearing points, but have different clearing points, the clearing point of the mixtures varying in a stepwise fashion from cell-to-cell but each mixture selectively reflecting the same colour in the grandjean state.
Claim 13
Dependent Claim
18 words
A device as claimed in claim 11 and wherein the said optically active compound is a cyanobiphenyl compound.
Claim 14
Dependent Claim
20 words
A device as claimed in claim 2 and wherein the cyanobiphenyl compound has a formula where R C is 2-methylbutyl.
Claim 15
Independent Claim
62 words
A device as claimed in any one of claims 11 to 13 and wherein the mixture of two optically active materials comprises a composition including the following three components: (i) the said optically active compound; (ii) a nematic liquid crystal material which is liquid crystalline at room temperature (20°C) ; and (iii) a liquid crystal material having a clearing point above 100°C.
Claim 16
Dependent Claim
75 words
A device as claimed in claim 14 and wherein the concentration of the said three components in the material of each cell is as follows: (i) from about 20% to about 80% by weight of the optically active compound; (ii) from about 20% to about 80% by weight of the material which is liquid crystalline at room temperature; (iii) from about 5% to about 25% of the liquid crystal material having a high clearing point.
Claim 17
Dependent Claim
49 words
A device as claimed in claim 14 or 15 and wherein the said optically active compound has a formula where R C is 2-methylbutyl, and wherein the material which is liquid crystalline at room temperature includes a plurality of cyanobiphenyl compounds at least one of which has a formula
Claim 18
Independent Claim
29 words
A device as claimed in any one of claims 14 to 16 and wherein the material which is liquid crystalline at room temperature includes a compound having a formula:
Claim 19
Independent Claim
32 words
A device as claimed in any one of the preceding claims and wherein the device is a clinical thermometer, the cells having clearing points in a range which includes the temperature 37°C.
Claim 20
Independent Claim
47 words
A device as claimed in any one of the preceding claims and wherein each cell includes a character or symbol, relating to the clearing point of the material of the cell, which can be seen when the material of the cell is not in its grandjean state.
Claim 21
Dependent Claim
40 words
A device as claimed in claim 19 and wherein the cells are deposited on a common substrate on which numerical values are printed corresponding to the temperatures represented by the cells, the cells being deposited where the values are printed.
Claim 22
Dependent Claim
26 words
A device as claimed in claim 20 and wherein the numerical values are in the form of clear areas on a dark background on the substrate.
Claim 23
Independent Claim
31 words
A device as claimed in any one of the preceding claims and which includes as the liquid crystal materials in the cells mixtures of the materials A and B defined herein.
Claim 24
Dependent Claim
22 words
A device as claimed in claim 22 and which is a device substantially as hereinbefore described with reference to the accompanying drawings.
References Cited (Backward Citations)
No citation records indexed.
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