Patent US3651696A successfully refreshed from Google Patents.
US3651696A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Linearized resistance bridge circuit operable in plurality from a common power supply
Assignee: Emerson Process Management Ltd
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Filing: 1969-07-15
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Granted: 1972-03-28
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Expires: 1989-07-15
Abstract
Abstract A bridge circuit suitable for platinum resistance thermometers having three lead wires. An operational amplifier varies the bridge excitation current in response to the bridge output to effect a desired degree of linearization or curve shaping between the sensing resistance and bridge output. The output is referenced to ground and a plurality of such bridges may be operated from a common power supply having a ground tap thus providing a flexible measuring system suitable for multipoint, continuous or scanning operations.
Inventors
- 👤 Robert C Rose
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 14:26
CPC Classifications
G; G01; G01R; G01R17/00; G01R17/10; G01R17/105; G01K; G01K7/00; G01K7/16; G01K7/18; G01K7/20; G01K7/21
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
289 words
A linearized resistance bridge circuit comprising first and second serially connected resistance means, the resistive value of said first means varying due to changes in the magnitude of a variable condition, third and fourth serially connected resistance means, said third and fourth resistance means being connected in parallel with said first and second resistance means, a tapped direct current power supply having its tap connected to a reference potential point, an operational amplifier having one power terminal connected to one side of said power supply and a second power terminal connected to the other side thereof and to the junction of said second and fourth resistance means, said operational amplifier also having input terminal means including first and second input terminals responsive to any difference in voltage applied thereto and an output terminal providing an output current to said first and third resistance means, said current varying in accordance with any such voltage difference applied to said input terminals, fifth resistance means connected at one end to the junction of said first and second resistance means and to said first input terminal and connected at its otHer end to said reference potential point, a pair of output signal terminals, one of said signal terminals being connected to the junction of said third and fourth resistance means and the other of said signal terminals being connected to said reference potential point, and means connected between said one signal terminal and said reference potential point for impressing a portion of the output signal voltage between said signal terminals to the input terminal means of said operational amplifier, whereby the magnitude of said output signal has a desired degree of linearity with respect to the resistive value of said first resistance means.
Claim 2
Dependent Claim
289 words
A linearized resistance bridge circuit comprising first and second serially connected resistance means, the resistive value of said first means varying due to changes in the magnitude of a variable condition, third and fourth serially connected resistance means, said third and fourth resistance means being connected in parallel with said first and second resistance means, a tapped direct current power supply having its tap connected to a reference potential point, an operational amplifier having one power terminal connected to one side of said power supply and a second power terminal connected to the other side thereof and to the junction of said second and fourth resistance means, said operational amplifier also having input terminal means including first and second input terminals responsive to any difference in voltage applied thereto and an output terminal providing an output current to said first and third resistance means, said current varying in accordance with any such voltage difference applied to said input terminals, fifth resistance means connected at one end to the junction of said first and second resistance means and to said first input terminal and connected at its otHer end to said reference potential point, a pair of output signal terminals, one of said signal terminals being connected to the junction of said third and fourth resistance means and the other of said signal terminals being connected to said reference potential point, and means connected between said one signal terminal and said reference potential point for impressing a portion of the output signal voltage between said signal terminals to the input terminal means of said operational amplifier, whereby the magnitude of said output signal has a desired degree of linearity with respect to the resistive value of said first resistance means.
Claim 3
Dependent Claim
72 words
The bridge circuit as defined in claim 1 in which said last-mentioned means includes sixth and seventh serially connected resistance means, one end of said sixth resistance means being connected to said reference terminal point and one end of said seventh resistance means being connected to said one signal terminal and the other ends of said sixth and seventh resistance means being connected to each other and to said second input terminal.
Claim 4
Dependent Claim
47 words
The bridge circuit as defined in claim 2 in which the resistive value of said seventh resistance means is appreciably greater than that of said sixth resistance means and the resistive value of said fifth resistance means is appreciably less than that of said sixth resistance means.
Claim 5
Dependent Claim
18 words
The bridge circuit as defined in claim 1 in which said reference potential point constitutes a common ground.
Claim 6
Dependent Claim
82 words
The bridge circuit as defined in claim 1 in which said first resistance means includes a temperature responsive resistance plus the resistance of one lead wire connected in series therewith, said third resistance means including a selected fixed resistance plus the resistance of a second lead wire connected in series therewith, and said circuit further including the resistance of a third lead wire connected between the output terminal of said operational amplifier and the junction of said first and third resistance means.
Claim 7
Dependent Claim
22 words
The bridge circuit as defined in claim 5 in which said second and fourth resistance means each includes a selected fixed resistance.
Claim 8
Dependent Claim
92 words
The bridge circuit as defined in claim 6 in which said second and fourth resistance means are equal and in which: where Eo the output voltage signal VB the voltage provided by the portion of the power supply between its said other side and said reference potential point R1 the resistive value of said first resistance means R2 the resistive value of said third resistance means R3 the resistive value of said second and fourth resistance means R6 the resistive value of said fifth resistance means K a desired portion of Eo.
Claim 9
Dependent Claim
256 words
Curve shaping bridge circuitry comprising a bridge circuit including first and second serially connected resistance means, the resistive value of said first means varying due to changes in the magnitude of a variable condition, third and fourth serially connected resistance means, said third and fourth resistance means being connected in parallel with said first and second resistance means, an operational amplifier having first and second input terminals responsive to any difference in potential applied thereto and an output terminal providing an output in accordance with any potential difference applied to said input terminals, said output terminal being connected to the junction of said first and third resistance means for supplying current to said junction, fifth resistance means connected between the junction of said first and second resistance means and ground, said first input terminal of said amplifier being connected to the junction of said first and second resistance means and hence to the end of said fifth resistance means remote from its grounded end, a first output signal terminal connected to sAid junction between said third and fourth resistance means, a second output signal terminal connected to ground, means connected between said first output signal terminal and ground for impressing a portion of the output signal between said signal terminals to the second input terminal of said operational amplifier, and power supply means for supplying power to said operational amplifier, said power supply means including a ground connection and furnishing a potential differing from ground potential to the junction of said second and fourth resistance means.
Claim 10
Dependent Claim
256 words
Curve shaping bridge circuitry comprising a bridge circuit including first and second serially connected resistance means, the resistive value of said first means varying due to changes in the magnitude of a variable condition, third and fourth serially connected resistance means, said third and fourth resistance means being connected in parallel with said first and second resistance means, an operational amplifier having first and second input terminals responsive to any difference in potential applied thereto and an output terminal providing an output in accordance with any potential difference applied to said input terminals, said output terminal being connected to the junction of said first and third resistance means for supplying current to said junction, fifth resistance means connected between the junction of said first and second resistance means and ground, said first input terminal of said amplifier being connected to the junction of said first and second resistance means and hence to the end of said fifth resistance means remote from its grounded end, a first output signal terminal connected to sAid junction between said third and fourth resistance means, a second output signal terminal connected to ground, means connected between said first output signal terminal and ground for impressing a portion of the output signal between said signal terminals to the second input terminal of said operational amplifier, and power supply means for supplying power to said operational amplifier, said power supply means including a ground connection and furnishing a potential differing from ground potential to the junction of said second and fourth resistance means.
Claim 11
Dependent Claim
54 words
Curve shaping bridge circuitry as defined in claim 8 in which said means for impressing a portion of the output signal to the second input terminal of said operational amplifier includes sixth and seventh serially connected resistance means, said second input terminal being connected to the junction of said sixth and seventh resistance means.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-03-28 | 1975-09-27 | 1976-03-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-03-28 | 1979-09-27 | 1980-03-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-03-28 | 1983-09-27 | 1984-03-28 | $7700.00 | Window Closed / Lapsed |