Stock material or miscellaneous articles – Composite – Of bituminous or tarry residue
Patent
1986-01-22
1989-12-05
Miller, Stanley D.
Stock material or miscellaneous articles
Composite
Of bituminous or tarry residue
350334, 350347V, 350330, 428 1, 25229964, 25229967, G02F 113
Patent
active
048848778
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates generally, as indicated, to liquid crystal devices for sensing temperature, to compositions of liquid crystal material and of containment media and to methods of making and using such liquid crystal material and media. The invention relates to temperature sensing and to thermometric uses of liquid crystal.
CROSS-REFERENCE TO RELATED PATENTS AND APPLICATIONS
U.S. Pat. No. 4,435,047, issued Mar. 6, 1984.
U.S. patent applications Ser. No. 477,138 and Ser. No. 477,242, both filed Mar. 21, 1983, now U.S. Pat. Nos. 4,606,611 and 4,616,903, respectively.
U.S. patent applications Ser. No. 480,461 and Ser. No. 480,466, both filed Mar. 30, 1983, now U.S. Pat. Nos. 4,662,720 and 4,596,445, respectively.
U.S. patent application Ser. No. 585,883, filed Mar. 2, 1984, now U.S. Pat. No. 4,707,080.
The inventor of the instant application also is the inventor in the above patent and applications. The disclosures of such patents and applications hereby are incorporated in their entireties by reference thereto.
BACKGROUND
Liquid crystal materials have been used in the past for temperature sensing purposes. An example of one liquid crystal temperature sensor is disclosed in U.S. Pat. No. 4,140,016. In that patent the temperature sensor employs nematic liquid crystal with an optically active ingredient to cause the nematic liquid crystal to twist so that light ordinarily would be reflected by the liquid crystal material when the temperature thereof is below a so-called transition point temperature or clearing point temperature (the same being used interchangeably herein), whereby the liquid crystal material is in a mesomorphic phase. However, on reaching and exceeding the transition or clearing point temperature, the liquid crystal enters an isotropic phase and becomes substantially optically transparent. The transition temperature can be selected as a function of the ingredients and proportions thereof which are employed to formulate the liquid crystal material. One disadvantage encountered with prior liquid crystal temperature sensors has been the difficulty in reading the same due to inadequate lighting.
Other prior liquid crystal temperature sensor devices have used cholesteric liquid crystal material which ordinarily undergoes a change in apparent color as a function of temperature. One disadvantage frequently encountered with cholesteric temperature sensing devices is the relatively slow reversing, indeed sometimes the non-reversible nature, of the material, for cholesteric liquid crystal frequently is known to have a relatively long relaxation and/or memory characteristic. Another disadvantage with cholesteric liquid crystal temperature sensors is the relatively low temperature maximum of, say, on the order of 100.degree. C. to which the same would be operatively responsive.
The encapsulation or otherwise containment of liquid crystal material, particularly operationally nematic liquid crystal material, in volumes formed in a containment, encapsulating or support medium, is disclosed in the above referenced patent and applications. Moreover, the liquid crystal material and containment medium therein disclosed cooperate such that in the absence of a prescribed input the containment medium tends to distort the natural liquid crystal structure to a so-called curvilinear or distorted alignment. The extraordinary index of refraction of the liquid crystal material, which occurs in the absence of such input, is greater than the index of refraction of the containment medium; and, therefore, incident light impinging on the contained liquid crystal material will tend to be scattered preferably substantially isotropically. However, in the presence of a prescribed input, such as an electric field, the liquid crystal structure tends to align with respect to such input; the ordinary index of refraction of the liquid crystal material preferably is fairly closely matched to that of the containment medium; and, accordingly, the account of scattering (or absorption) of the incident ligh
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Gallivan Richard
Manchester R & D Partnership
Miller Stanley D.
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