Patent US3599105A successfully refreshed from Google Patents.
US3731535A
Expired / Lapsed
US
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Temperature responsive apparatus
Assignee: Individual
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Filing: 1970-08-07
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Granted: 1973-05-08
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Expires: 1990-08-07
Abstract
Abstract There is disclosed apparatus for measuring precisely, to 0.01 C*, difference in temperature including thermistors, which are subject to the temperatures whose difference is being measured. The logarithm of electrical resistance of each thermistor is proportional to its temperature and the thermistors are connected in a ratiometric circuit for measuring their relative resistances. Each thermistor is a ceramic of ferroelectric material (for example, barium-strontium titanate) formed by mixing powders of different compositions, each composition having a different ferroelectric resistance anomaly, and then firing and oxidizing bodies pressed from the mixture of powders. The mixture of powders is heterogeneous so that the grains of the ceramic include a plurality of particles of powder which microscopically would manifest distinct ferroelectric resistance anomalies if fired alone but the macroscopic response of the ceramic is loglinear over a substantial temperature range.
Inventors
- 👤 R Wendt
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 02:32
CPC Classifications
H; H01; H01C; H01C7/00; H01C7/04; G; G01; G01K; G01K3/00; G01K3/08; G01K3/14
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
23 words
The apparatus of claim 1 wherein the ferroelectric powder is barium-strontium titanate and each grain is agglomerated of powders of different barium-strontium ratio.
Claim 2
Dependent Claim
67 words
The apparatus of claim 1 wherein the agglomerate of powders are mixed with such heterogeneity that the grains of the ensemble contain powders of different ferroelectric anomalies and the ensemble of grains manifests a multiplicity of distinct ferroelectric temperature-resistance characteristics, whereby, for the overall thermistor, the logarithm of the resistance of the thermistor is a substantially linear function of the temperature over the temperature range being measured.
Claim 3
Dependent Claim
52 words
The apparatus of claim 1 wherein the indicating means includes ratiometric amplifying means connected in amplifying relationship with the thermistors to produce an indicating signal which is substantially larger than, but a linear function of, the logarithm of the quotient of the resistances of the thermistors at the first and second regions.
Claim 4
Dependent Claim
21 words
The apparatus of claim 1 wherein the agglomerate powders mixed in the grains have discrete resistance anomalies spaced about 15* centigrade.
Claim 5
Dependent Claim
20 words
The apparatus of claim 5 wherein the powders are composed of strontium-barium titanate having different ratios of strontium to barium.
Claim 6
Independent Claim
105 words
The method of measuring the temperature of a system at a region which comprises subjecting a mass of grains of ferroelectric material to the temperature of said system at said region thereby varying the barrier potential between said grains in accordance with said temperature and measuring the variation of said barrier potential, the grains being made up of a mixture of powders of ferroelectric materials of different composition, the mixture making up the grains being heterogeneous so that the temperature-resistance characteristic of each grain is an average composite of a plurality of distinct ferroelectric resistance anomalies and the composite resistance of the thermistor is log-linear.
Claim 7
Dependent Claim
20 words
The method of claim 1 wherein the powders are composed of strontium-barium titanate having different ratios of strontium to barium.
Claim 8
Dependent Claim
98 words
Apparatus for measuring difference in temperature at first and second regions of a system comprising a first thermistor, thermally connected to said system at said first region, a second thermistor thermally connected to said system at said second region, and means, responsive to the relation of the resistances of said thermistors at the temperatures of said regions, for indicating said difference in temperature, each of said thermistors being composed of grains, each grain agglomerated of powders of ferroelectric materials of different composition, such that for each thermistor the resistance as a function of temperature has a desired form.
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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) | 1976-05-07 | 1976-11-06 | 1977-05-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-05-07 | 1980-11-06 | 1981-05-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-05-07 | 1984-11-06 | 1985-05-08 | $7700.00 | Window Closed / Lapsed |