US4385844A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Novel compositions, devices and method
Assignee: Becton Dickinson and Co
•
Filing: 1980-09-22
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Granted: 1983-05-31
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Expires: 2000-09-22
Abstract
Abstract Disclosure is made of novel temperature sensing devices such as temperature indicating and recording devices. The devices of the invention differ from prior art devices in that they employ new and improved temperature indicating compositions. The temperature indicating compositions of the invention comprise an optically active, non-cholesteric inert compound in admixture with nematic type liquid crystal compounds. The optically active, inert compounds lend a visible point of reference to the compositions when the liquid crystals pass through their liquid transition points. The proportion of optically active, inert compounds added to the nematic liquid crystals is that proportion which will impart chirality or twist to the compositions of the invention and is dependent upon the twisting power of the optically active ingredient. The compositions of the invention are unique in that they possess very sharp liquid transition points, i.e.; clearing points over a very narrow temperature range. This is an ideal characteristic for compositions to be employed as accurate sensors of specific temperatures.
Inventors
- 👤 James L. Fergason
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 11:37
CPC Classifications
C; C09; C09K; C09K19/00; C09K19/52; C09K19/58; C09K19/586; G; G01; G01K; G01K11/00; G01K11/12; G01K11/16; G01K11/165; G01K13/00; G01K13/20
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
115 words
A temperature indicating composition for use in a thermometric device, which comprises; (a) 25 to 60 percent by weight of an optically active, non-cholesteric, inert compound; in admixture with (b) 40 to 75 percent by weight of a mixture of two different nematic types of liquid crystal selected from the group consisting of 4-alkylphenyl-4-alkoxybenzoates, 4-alkylphenyl-4-alkylbenzoates, 4-alkoxyphenyl-4-alkylbenzoates, and 4-alkoxyphenyl-4-alkoxybenzoates, said two having liquid transition points within about 20° C. of each other; the proportion of (a) being that which selectively scatters light from the visible spectrum at temperatures below the liquid transition point for said composition and which will impart a color change to the composition when the composition is warmed to its liquid transition point.
Claim 2
Dependent Claim
115 words
A temperature indicating composition for use in a thermometric device, which comprises; (a) 25 to 60 percent by weight of an optically active, non-cholesteric, inert compound; in admixture with (b) 40 to 75 percent by weight of a mixture of two different nematic types of liquid crystal selected from the group consisting of 4-alkylphenyl-4-alkoxybenzoates, 4-alkylphenyl-4-alkylbenzoates, 4-alkoxyphenyl-4-alkylbenzoates, and 4-alkoxyphenyl-4-alkoxybenzoates, said two having liquid transition points within about 20° C. of each other; the proportion of (a) being that which selectively scatters light from the visible spectrum at temperatures below the liquid transition point for said composition and which will impart a color change to the composition when the composition is warmed to its liquid transition point.
Claim 3
Dependent Claim
30 words
The composition of claim 1 wherein the concentration of the optically active, inert compound is such that the pitch of the composition is in the range between 680μ and 440μ.
Claim 4
Dependent Claim
13 words
The composition of claim 2 wherein the range is between 600μ and 480μ.
Claim 5
Dependent Claim
28 words
The composition of claim 1 wherein the optically active, inert compound has a twist, divided by the index of refraction for the liquid crystal, of less than 550μ.
Claim 6
Dependent Claim
73 words
An improved temperature recording device, which comprises; an opaque support member; a first liquid crystal composition disposed on said support member, said composition comprising a composition according to claim 1; and a second liquid crystal composition disposed on said support member, said second composition comprising a composition according to claim 1; the liquid transition point for said first liquid crystal composition differing from the liquid transition point for said second liquid crystal composition.
Claim 7
Dependent Claim
28 words
The device of claim 5 wherein said support member is a dark colored material which is physically and chemically inert towards the first and second liquid crystal compositions.
Claim 8
Dependent Claim
33 words
The device of claim 5 wherein said first and second liquid crystal compositions are disposed on said support member by coating thereon in a thickness of from about 10 to about 125 microns.
Claim 9
Dependent Claim
25 words
The device of claim 5 wherein said first and second compositions are covered with a transparent or translucent film to protect them from the atmosphere.
Claim 10
Dependent Claim
15 words
The device of claim 5 wherein said first and second liquid crystal composition are encapsulated.
Claim 11
Dependent Claim
33 words
The deveice of claim 5 wherein the concentration of the optically active, inert compound in each composition is such that the pitch of the composition is in the range between 680μ and 440μ.
Claim 12
Dependent Claim
13 words
The device of claim 10 wherein the range is between 600μ and 480μ.
Claim 13
Dependent Claim
31 words
The device of claim 5 wherein the optically active, inert compound in each composition has a twist, divided by the index of refraction for the liquid crystal, of less than 550μ.
Claim 14
Dependent Claim
28 words
A temperature recording device which comprises; an opaque support member; and a temperature indicating composition, which comprises a composition according to claim 1 disposed on said support member.
Claim 15
Dependent Claim
46 words
A device according to claim 13 wherein a plurality of temperature indicating compositions are disposed on said support member, each of said compositions differing from the other in liquid transition point, said liquid transition points being spread over a range of from 0° to 100° C.
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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) | 1986-05-30 | 1986-11-29 | 1987-05-31 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-05-30 | 1990-11-29 | 1991-05-31 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-05-30 | 1994-11-29 | 1995-05-31 | $7700.00 | Window Closed / Lapsed |