US3644864A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Composite thermistor temperature sensor having step-function response
Assignee: Texas Instruments Inc
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Filing: 1969-12-05
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Granted: 1972-02-22
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Expires: 1989-12-05
Abstract
Abstract A temperature sensor including first and second PTC thermistor elements each having a well-defined transition temperature above which the resistance of the element rises relatively abruptly and below which it changes relatively little, the transition temperature of the second element being substantially greater than that of the first element. The thermistor elements are adapted to be substantially identically thermally responsive to a body whose temperature is sensed by the sensor. The elements are connected in series-circuit relationship to cause the sensor resistance to be a series-equivalent resistance which varies as a function of the resistance of the elements and changes relatively abruptly at temperatures determined by the transition temperatures of the elements thereby providing the sensor with a step-function R vs. T characteristic.
Inventors
- 👤 Hans G Hirsbrunner
- 👤 Lyle E Mcbride Jr
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 13:04
CPC Classifications
G; G01; G01K; G01K7/00; G01K7/16; G01K7/22; G01K7/24; G01K15/00; H; H01; H01C; H01C7/00; H01C7/02; H01C7/022; H02; H02H; H02H5/00; H02H5/04; H02H5/042
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
217 words
A temperature sensor for use in a control circuit adapted to perform first and second control functions in response to changes in the resistance of said sensor at respective first and second control temperatures determined by said sensor, said sensor comprising a first thermistor element having a positive temperature coefficient and a well-defined transition temperature above which the resistance thereof rises relatively abruptly and below which the resistance thereof changes relatively little and a second thermistor element having a positive temperature coefficient and a transistor temperature, greater than that of said first element, above which the resistance thereof rises relatively abruptly and below which the resistance thereof changes relatively little; said elements being substantially identically thermally responsive to a source of heat, said elements being connected in series-circuit relationship whereby the resistance of said sensor is a series-equivalent resistance which varies as a funcTion of the resistances of said elements and changes relatively abruptly at said control temperatures, the latter being determined by the transition temperatures of said elements; a substantially temperature-insensitive resistance which does not vary substantially with respect to changes in the temperature sensed by said sensor, said temperature-insensitive resistance being parallel-connected with said first element and having a resistance value substantially greater than the resistance of said second element at the transition temperature thereof.
Claim 2
Dependent Claim
217 words
A temperature sensor for use in a control circuit adapted to perform first and second control functions in response to changes in the resistance of said sensor at respective first and second control temperatures determined by said sensor, said sensor comprising a first thermistor element having a positive temperature coefficient and a well-defined transition temperature above which the resistance thereof rises relatively abruptly and below which the resistance thereof changes relatively little and a second thermistor element having a positive temperature coefficient and a transistor temperature, greater than that of said first element, above which the resistance thereof rises relatively abruptly and below which the resistance thereof changes relatively little; said elements being substantially identically thermally responsive to a source of heat, said elements being connected in series-circuit relationship whereby the resistance of said sensor is a series-equivalent resistance which varies as a funcTion of the resistances of said elements and changes relatively abruptly at said control temperatures, the latter being determined by the transition temperatures of said elements; a substantially temperature-insensitive resistance which does not vary substantially with respect to changes in the temperature sensed by said sensor, said temperature-insensitive resistance being parallel-connected with said first element and having a resistance value substantially greater than the resistance of said second element at the transition temperature thereof.
Claim 3
Dependent Claim
36 words
A temperature sensor as set forth in claim 1 wherein said elements are cylindrical in form and have generally transverse coplanar ends, said elements being secured together in end-to-end relationship to provide said series circuit relationship.
Claim 4
Dependent Claim
26 words
A temperature sensor as set forth in claim 2 wherein each of said elements includes electrical contact means comprising a metallized area on opposite ends thereof.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-02-21 | 1975-08-23 | 1976-02-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-02-21 | 1979-08-23 | 1980-02-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-02-21 | 1983-08-23 | 1984-02-22 | $7700.00 | Window Closed / Lapsed |