US3845348A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Differential pressure transducer force motor drive circuit
Assignee: Elsag International BV
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Filing: 1971-11-01
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Granted: 1974-10-29
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Expires: 1991-11-01
Abstract
Abstract A circuit for controlling a force motor in a pressure transducer. A change in pressure causes a change in the inductance of a coil in the pressure transducer. A Wien bridge oscillator circuit responsive to this inductance change generates an alternating signal proportional to the inductance. The alternating signal is peak detected, held and amplified to generate a d-c voltage proportional to the inductance. A current amplifier controlled by the d-c voltage provides a current to force motor winding that is proportional to the inductance. Normally, a variable shunt resistance is placed across the force motor winding. The circuit includes a feedback network which keeps the frequency response of the circuit independent of the value of the shunting resistance.
Inventors
- 👤 J Riley
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 23:16
CPC Classifications
G; G01; G01L; G01L13/00; G01L13/02; G01L13/025; G01L11/00; G01L11/004; G01L11/008; G01L9/00; G01L9/0041; G01L9/007; G01L9/10; G01L9/105
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
138 words
In a force balance transducer system including a position detector means, a coil having a variable inductance determined by the position detector means, and a motor means for balancing the transducer, said motor means having a motor winding circuit including a variable resistance connected in electrical parallel with said motor winding, an improved motor drive circuit comprising current amplifier circuit means responsive to the inductance of said coil for supplying a d-c current proportional to said inductance to said motor winding circuit, said circuit means including a negative feedback network connected in electrical series with the motor winding itself for feeding back part of the motor winding voltage to said amplifier circuit so that the frequency response of said motor drive circuit is maintained substantially independent of the value of resistance that is connected across said motor winding.
Claim 2
Dependent Claim
138 words
In a force balance transducer system including a position detector means, a coil having a variable inductance determined by the position detector means, and a motor means for balancing the transducer, said motor means having a motor winding circuit including a variable resistance connected in electrical parallel with said motor winding, an improved motor drive circuit comprising current amplifier circuit means responsive to the inductance of said coil for supplying a d-c current proportional to said inductance to said motor winding circuit, said circuit means including a negative feedback network connected in electrical series with the motor winding itself for feeding back part of the motor winding voltage to said amplifier circuit so that the frequency response of said motor drive circuit is maintained substantially independent of the value of resistance that is connected across said motor winding.
Claim 3
Dependent Claim
120 words
In a force balance transducer system including a position detector means, a coil having a variable inductance determined by the position detector means, a motor means for balancing the transducer, said motor means having a motor winding circuit including a variable resistance connected in electrical parallel with said motor winding, and an improved motor drive circuit, the amplifier circuit means as in claim 1 further comprising: a capacitance element and resistance means coupled in electrical series with said motor winding circuit for feeding back part of the motor winding voltage to the amplifier means so that the frequency response of the motor drive circuit is preserved substantially independent of the value of resistance that is connected across said motor winding.
Claim 4
Dependent Claim
167 words
In a force balance transducer system including a position detector means, a coil having a variable inductance determined by the position detector means, a motor means for balancing the transducer, said motor means having a motor winding circuit including a variable resistance connected in electrical parallel with said motor winding, an improved motor drive circuit comprising: a. a Wien bridge oscillator circuit including circuit means responsive to the inductance of said coil, said Wien bridge oscillator circuit generating an output signal proportional to said inductance; b. amplifier circuit means responsive to said oscillator output signal for supplying a d-c current proportional to said inductance to said motor winding circuit; and c. a negative feedback network connected in electrical series with the motor winding circuit for feeding back to said amplifier circuit means part of the motor winding voltage to said amplifier so that the frequency response of said motor drive circuit is maintained substantially independent of the value of resistance that is connected across said motor winding.
Claim 5
Dependent Claim
167 words
In a force balance transducer system including a position detector means, a coil having a variable inductance determined by the position detector means, a motor means for balancing the transducer, said motor means having a motor winding circuit including a variable resistance connected in electrical parallel with said motor winding, an improved motor drive circuit comprising: a. a Wien bridge oscillator circuit including circuit means responsive to the inductance of said coil, said Wien bridge oscillator circuit generating an output signal proportional to said inductance; b. amplifier circuit means responsive to said oscillator output signal for supplying a d-c current proportional to said inductance to said motor winding circuit; and c. a negative feedback network connected in electrical series with the motor winding circuit for feeding back to said amplifier circuit means part of the motor winding voltage to said amplifier so that the frequency response of said motor drive circuit is maintained substantially independent of the value of resistance that is connected across said motor winding.
Claim 6
Dependent Claim
101 words
An improved force balance transducer system as recited in claim 3 wherein said d-c current supplying means comprises a conversion circuit responsive to said oscillator output signal for generating a d-c voltage proportional to said inductance and a current drive circuit responsive to said d-c voltage for supplying a d-c current proportional to said inductance to said motor winding circuit, said conversion circuit including a feedback network for feeding back to said amplifier part of the motor winding voltage so that the frequency response of said motor drive circuit is substantially independent of the amount of resistance across said motor winding.
Claim 7
Dependent Claim
72 words
An improved force balance system as recited in claim 4 wherein said conversion circuit comprises a peak detection circuit for generating a d-c voltage substantially equal to the peak amplitude of saId oscillator output signal and said amplifier comprises a d-c differential amplifier responsive to said peak detected amplitude and to a d-c reference voltage for generating a d-c voltage proportional to said inductance, said d-c differential circuit including said feedback network.
Claim 8
Dependent Claim
40 words
An improved force balance system as recited in claim 5 wherein said force motor drive circuit further comprises a voltage regulator circuit responsive to the voltage of said power supply for providing a regulated voltage to said Wien bridge oscillator.
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) | 1977-10-28 | 1978-04-29 | 1978-10-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-10-28 | 1982-04-29 | 1982-10-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-10-28 | 1986-04-29 | 1986-10-29 | $7700.00 | Window Closed / Lapsed |