Patent US3906796A successfully refreshed from Google Patents.
US3906796A
Expired / Lapsed
US
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Electronic temperature measuring apparatus
Assignee: Individual
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Filing: 1974-01-14
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Granted: 1975-09-23
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Expires: 1994-01-14
Abstract
Abstract Temperature is measured by sensing the voltage across two series resistors, one a reference resistor and the other a temperature variable resistor such as platinum. Two matched constant current sources pass current in opposite directions toward the junction of the resistors to produce a null at a predetermined temperature such as 0*F or 0*C, for example. If high accuracy is required, linearization is provided for matching the temperature characteristic of the variable sensor resistor with a linear voltage scale of a digital voltmeter, for example, to permit use of a conventional voltmeter arrangement to read out degrees directly in either Centigrade or Fahrenheit. Also tracking is accomplished over a wider temperature range by increasing the current output from the current sources by a feedback arrangement as the variable resistance increases.
Inventors
- 👤 Robert Francis Dumbeck
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-22 21:29
CPC Classifications
G; G01; G01K; G01K7/00; G01K7/16; G01K7/18; G01K7/20; G01K7/21
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
269 words
Apparatus for producing a direct readout of temperature in degrees on a linear scale of a voltmeter from the change of resistance of a single temperature variable resistor comprising in combination, a temperature responsive circuit coupled between a pair of temperature measurement output terminals to develop a voltage thereat changing in a substantially linear relationship corresponding in degrees of temperature to said linear scale said circuit including said temperature variable resistor and a reference resistor of fixed resistance, both being conductively connected together at a common intermediate access terminal, said pair of temperature measurement output terminals conductively connected to the respective opposite ends of said two resistors, means developing a voltage at said terminals varying in response to temperature as a function of resistance change in said temperature variable resistor consisting of a pair of current sources each having a like pole conductively coupled respectively to said two output terminals to pass current through the respective two said resistors to said intermediate terminal to establish at a null temperature setting of 0* a cancellation of voltage drops across said two resistors as measured at said pair of output terminals, a voltmeter circuit incorporating said linear scale and responding to the voltage produced at said pair of output terminals thereby registering by changes of voltage an indication on said scale of the degrees of temperature at said variable resistor, and a potentiometer connecting each said current source together with the variable arm conductively coupled to said common intermediate access terminal for balancing current flows from the respective current sources at 0* to produce a null reading on said voltmeter scale.
Claim 2
Dependent Claim
269 words
Apparatus for producing a direct readout of temperature in degrees on a linear scale of a voltmeter from the change of resistance of a single temperature variable resistor comprising in combination, a temperature responsive circuit coupled between a pair of temperature measurement output terminals to develop a voltage thereat changing in a substantially linear relationship corresponding in degrees of temperature to said linear scale said circuit including said temperature variable resistor and a reference resistor of fixed resistance, both being conductively connected together at a common intermediate access terminal, said pair of temperature measurement output terminals conductively connected to the respective opposite ends of said two resistors, means developing a voltage at said terminals varying in response to temperature as a function of resistance change in said temperature variable resistor consisting of a pair of current sources each having a like pole conductively coupled respectively to said two output terminals to pass current through the respective two said resistors to said intermediate terminal to establish at a null temperature setting of 0* a cancellation of voltage drops across said two resistors as measured at said pair of output terminals, a voltmeter circuit incorporating said linear scale and responding to the voltage produced at said pair of output terminals thereby registering by changes of voltage an indication on said scale of the degrees of temperature at said variable resistor, and a potentiometer connecting each said current source together with the variable arm conductively coupled to said common intermediate access terminal for balancing current flows from the respective current sources at 0* to produce a null reading on said voltmeter scale.
Claim 3
Dependent Claim
42 words
Apparatus as defined in claim 1, wherein said temperature variable resistor has a nonlinear rElationship of resistance change over a predetermined temperature range, and including in said voltmeter circuit a linearization network providing a voltmeter scale output directly in degrees of temperature.
Claim 4
Dependent Claim
14 words
Apparatus as defined in claim 2, wherein said temperature variable resistor is of platinum.
Claim 5
Dependent Claim
27 words
Apparatus as defined in claim 1, wherein each current source comprises an operational amplifier which has positive feedback to produce a gain proportional to the output current.
Claim 6
Dependent Claim
220 words
Apparatus for producing a readout of temperature from the change of resistance of a single temperature variable resistor comprising in combination, a circuit coupled between a pair of temperature measurement output terminals including said temperature variable resistor and a reference resistor of fixed resistance both being connected together at a common intermediate access terminal and a pair of temperature measurement output terminals connected to the respective opposite ends of said two resistors, means developing a voltage at said terminals varying in response to temperature consisting of a pair of current sources each having a like pole coupled respectively to said two output terminals to pass current through the respective said resistors to said intermediate terminal to establish at a null temperature setting such as 0*C a cancellation of voltage drops across said two resistors as measured at said pair of output terminals, and a voltmeter connected to said pair of output terminals thereby registering by changes of voltage an indication of the temperature at said variable resistor, including a voltmeter zero set circuit coupled between said voltmeter and one of said terminals comprising a sink resistor, a two pole variably adjustable current source, and a circuit connecting said two poles of said current source to opposite ends of said sink resistor thereby to pass current only through said sink resistor.
Claim 7
Dependent Claim
220 words
Apparatus for producing a readout of temperature from the change of resistance of a single temperature variable resistor comprising in combination, a circuit coupled between a pair of temperature measurement output terminals including said temperature variable resistor and a reference resistor of fixed resistance both being connected together at a common intermediate access terminal and a pair of temperature measurement output terminals connected to the respective opposite ends of said two resistors, means developing a voltage at said terminals varying in response to temperature consisting of a pair of current sources each having a like pole coupled respectively to said two output terminals to pass current through the respective said resistors to said intermediate terminal to establish at a null temperature setting such as 0*C a cancellation of voltage drops across said two resistors as measured at said pair of output terminals, and a voltmeter connected to said pair of output terminals thereby registering by changes of voltage an indication of the temperature at said variable resistor, including a voltmeter zero set circuit coupled between said voltmeter and one of said terminals comprising a sink resistor, a two pole variably adjustable current source, and a circuit connecting said two poles of said current source to opposite ends of said sink resistor thereby to pass current only through said sink resistor.
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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) | 1978-09-22 | 1979-03-24 | 1979-09-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-09-22 | 1983-03-24 | 1983-09-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-09-22 | 1987-03-24 | 1987-09-23 | $7700.00 | Window Closed / Lapsed |