Patent US3774089A successfully refreshed from Google Patents.
US3774089A
Expired / Lapsed
US
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Temperature indicating apparatus using oppositely varying capacitors
Assignee: Bell and Howell Co
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Filing: 1972-04-18
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Granted: 1973-11-20
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Expires: 1992-04-18
Abstract
Abstract A temperature sensitive transducer element includes a structure having a cavity. Each of a pair of inwardly facing conductive surfaces defining the cavity forms a plate of a different one of a pair of capacitors. A support member disposed in the cavity has a pair of outwardly facing conductive surfaces each forming the opposite plate of a different one of the two capacitors. As the ambient temperature varies, the support member translates relative to the structure along a line between the inwardly facing surfaces so that the capacitance of one of the capacitors increases and the capacitance of the other decreases. Preferably, each capacitor controls the frequency of oscillation of a different oscillator circuit. A mixer circuit responsive to the oscillator circuits produces a square wave the frequency of which is an analog indication of ambient temperature. A counting circuit converts the analog indication into a digital representation.
Inventors
- 👤 H Lewis
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 14:23
CPC Classifications
G; G01; G01K; G01K7/00; G01K7/34
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
158 words
A variable-capacitance, temperature-indicating element comprising: a first and a second conductive surface, non-conductive means mounting the conductive surfaces to define opposing faces of a cavity; a support member disposed in the cavity between the conductive surfaces and having third and fourth conductive surfaces spaced from and opposing the first and second conductive surfaces, respectively, thereby to define first and second capacitors, a plurality of signal leads each connected to a different one of the conductive surfaces for separately connecting the first and second capacitors into an external operating electrical circuit; and means responsive to variations in ambient temperature for translating the support member along a line between the first and second surfaces so that the capacitance of the first capacitor increases and the capacitance of the second capacitor decreases with the capacitance of each capacitor changing in an amount sufficient to differentially affect the operation of the external circuit thereby to provide an indication of the ambient temperature.
Claim 2
Dependent Claim
158 words
A variable-capacitance, temperature-indicating element comprising: a first and a second conductive surface, non-conductive means mounting the conductive surfaces to define opposing faces of a cavity; a support member disposed in the cavity between the conductive surfaces and having third and fourth conductive surfaces spaced from and opposing the first and second conductive surfaces, respectively, thereby to define first and second capacitors, a plurality of signal leads each connected to a different one of the conductive surfaces for separately connecting the first and second capacitors into an external operating electrical circuit; and means responsive to variations in ambient temperature for translating the support member along a line between the first and second surfaces so that the capacitance of the first capacitor increases and the capacitance of the second capacitor decreases with the capacitance of each capacitor changing in an amount sufficient to differentially affect the operation of the external circuit thereby to provide an indication of the ambient temperature.
Claim 3
Dependent Claim
44 words
A transducer element according to claim 1 wherein the first and second conductive surfaces are each substantially planar and are parallel to each other, and wherein the translating means translates the support member along a line perpendicular to the first and second conductive surfaces.
Claim 4
Dependent Claim
58 words
A transducer element according to claim 1 wherein the translating means includes a carrier member having one end joined to the support member and an opposite end held in substantially fixed spacial relationship with the cavity, the carrier member responding to variations in ambient temperature to change the spacing between its ends, thereby to translate the support member.
Claim 5
Dependent Claim
95 words
A temperature transducer element according to claim 1, wherein the non-conductive means includes a securing member having opposite end portions one of which joins the first to the second conductive surface, and the translating means includes a carrier member having one end joined to the support member and an opposite end portion held in fixed spacial relationship with the other end portion of the securing member, the securing member having a different temperature coefficient of expansion from the carrier member so that they expand and contract by different amounts responsive to variations in ambient temperature.
References Cited (Backward Citations)
GB620184A
Cited
US3460011A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-11-19 | 1977-05-21 | 1977-11-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-11-19 | 1981-05-21 | 1981-11-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-11-19 | 1985-05-21 | 1985-11-20 | $7700.00 | Window Closed / Lapsed |