US4353254A
Expired / Lapsed
US
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Control circuit for electro-static accelerometer
Assignee: Singer Co
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Filing: 1980-12-18
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Granted: 1982-10-12
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Expires: 2000-12-18
Abstract
Abstract An electro-static capacitive accelerometer is a square law device and includes two fixed plates and an intermediary movable plate. A control circuit detects unbalances in the accelerometer, due to acceleration, and generates a signal which induces a corresponding electro-static corrective torque on the accelerometer thus forcing it toward a null condition. The signal is proportional to the acceleration. The invention eliminates prior art summing amplifiers in the control circuit for linearizing the torque of the accelerometer.
Inventors
- 👤 George F. Schroeder
- 👤 Edward A. Demers
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 18:21
CPC Classifications
G; G01; G01P; G01P15/00; G01P15/02; G01P15/08; G01P15/125; G01P15/13; G01P15/131
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
237 words
A control circuit for an electro-static capacitive accelerometer which includes two fixed plates and a movable intermediary plate, the circuits comprising: a reference source of DC power; a plurality of interconnected resistive means connected at their outer terminals across the output of the power source for generating DC voltages thereacross; phase sensitive demodulator means having a first input connected to a reference AC voltage source and a second input connected in circuit with the accelerometer to detect capacitive imbalances thereof; integrating means connected to the output of the demodulator means for generating a signal corresponding to the integral of the capacitive imbalance; feedback means connecting the integral signal to a junction between the resistive means; means connecting the fixed plates of the accelerometer to outer terminals of the resistive means; terminal means connected to the output of the integrating means for permitting measurement of the integral signal; wherein the reference AC voltage is derived from a terminal of a transformer, a secondary winding of the transformer being connected in circuit with fixed plates of the accelerometer, and further wherein means are connected between a center tap of the secondary winding and the second input of the phase sensitive demodulator; and wherein a resistor is connected at a first terminal thereof to the output of the integrating means and at a second terminal thereof to both the resistive means junction and the second input of the demodulator means.
Claim 2
Dependent Claim
237 words
A control circuit for an electro-static capacitive accelerometer which includes two fixed plates and a movable intermediary plate, the circuits comprising: a reference source of DC power; a plurality of interconnected resistive means connected at their outer terminals across the output of the power source for generating DC voltages thereacross; phase sensitive demodulator means having a first input connected to a reference AC voltage source and a second input connected in circuit with the accelerometer to detect capacitive imbalances thereof; integrating means connected to the output of the demodulator means for generating a signal corresponding to the integral of the capacitive imbalance; feedback means connecting the integral signal to a junction between the resistive means; means connecting the fixed plates of the accelerometer to outer terminals of the resistive means; terminal means connected to the output of the integrating means for permitting measurement of the integral signal; wherein the reference AC voltage is derived from a terminal of a transformer, a secondary winding of the transformer being connected in circuit with fixed plates of the accelerometer, and further wherein means are connected between a center tap of the secondary winding and the second input of the phase sensitive demodulator; and wherein a resistor is connected at a first terminal thereof to the output of the integrating means and at a second terminal thereof to both the resistive means junction and the second input of the demodulator means.
Claim 3
Dependent Claim
27 words
The subject matter of claim 1 wherein the plurality of interconnected resistive means includes a pair of precision resistors of equal resistance connected together at the junction.
Claim 4
Dependent Claim
210 words
A control circuit for an electro-static capacitive accelerometer which includes two fixed plates and an intermediary movable plate, the circuit comprising: a reference source of DC power; a pair of resistors of substantially equal resistance connected together at a junction, the outward terminals of the resistors connected across the power source; a transformer having a reference AC signal at the primary winding thereof; the secondary winding of the transformer connected across the accelerometer via respective DC blocking capacitors; means connecting outward terminals of the resistors across the accelerometer; a phase sensitive demodulator having a first input thereof connected to the transformer primary and a second input thereof connected to a center tap of the secondary winding for detecting capacitive imbalances; means connected at the output of the phase sensitive demodulator for integrating output signals corresponding to a signal associated with the integral of capacitive imbalance; feedback means connecting the integral signal to the junction between resistors; a terminal connected to the output of the integrating means for permitting measurement of the integral signals; a preamplifier connected between the center tap and the input of the demodulator; together with inverter means inductively coupled to the reference source of DC power for providing DC isolation at the input of the reference source.
Claim 5
Dependent Claim
210 words
A control circuit for an electro-static capacitive accelerometer which includes two fixed plates and an intermediary movable plate, the circuit comprising: a reference source of DC power; a pair of resistors of substantially equal resistance connected together at a junction, the outward terminals of the resistors connected across the power source; a transformer having a reference AC signal at the primary winding thereof; the secondary winding of the transformer connected across the accelerometer via respective DC blocking capacitors; means connecting outward terminals of the resistors across the accelerometer; a phase sensitive demodulator having a first input thereof connected to the transformer primary and a second input thereof connected to a center tap of the secondary winding for detecting capacitive imbalances; means connected at the output of the phase sensitive demodulator for integrating output signals corresponding to a signal associated with the integral of capacitive imbalance; feedback means connecting the integral signal to the junction between resistors; a terminal connected to the output of the integrating means for permitting measurement of the integral signals; a preamplifier connected between the center tap and the input of the demodulator; together with inverter means inductively coupled to the reference source of DC power for providing DC isolation at the input of the reference source.
Claim 6
Dependent Claim
169 words
A control circuit for an electro-static capacitive accelerometer which includes two fixed plates and an intermediary movable plate, the circuit comprising: a reference source of DC power; inverter means inductively coupled to the reference source for providing DC isolation at the input of the source; a pair of resistors of substantially equal resistance connected together at a junction, the outward terminals of the resistors connected across the power supply; means connecting the outward resistor terminals in parallel with the fixed accelerometer plate; a phase sensitive demodulator having a first input thereof connected in circuit with the junction and a second input thereof connected to the inverter means, the demodulator detecting capacitive imbalance in the accelerometer; means connected at the output of the phase sensitive demodulator for integrating output signals corresponding to a signal associated with capacitive imbalances; a feedback resistor connected between the output of the integrating means and the junction; and a terminal connected to the output of the integrating means for allowing measurement of the integral signal.
Claim 7
Dependent Claim
169 words
A control circuit for an electro-static capacitive accelerometer which includes two fixed plates and an intermediary movable plate, the circuit comprising: a reference source of DC power; inverter means inductively coupled to the reference source for providing DC isolation at the input of the source; a pair of resistors of substantially equal resistance connected together at a junction, the outward terminals of the resistors connected across the power supply; means connecting the outward resistor terminals in parallel with the fixed accelerometer plate; a phase sensitive demodulator having a first input thereof connected in circuit with the junction and a second input thereof connected to the inverter means, the demodulator detecting capacitive imbalance in the accelerometer; means connected at the output of the phase sensitive demodulator for integrating output signals corresponding to a signal associated with capacitive imbalances; a feedback resistor connected between the output of the integrating means and the junction; and a terminal connected to the output of the integrating means for allowing measurement of the integral signal.
Claim 8
Dependent Claim
23 words
The subject matter set forth in claim 4 together with a preamplifier connected between the center tap and the input of the demodulator.
Claim 9
Dependent Claim
168 words
A control signal for an electro-static capacitive accelerometer which includes two fixed plates and a movable intermediary plate, the circuits comprising: a reference source of DC power; means connected at the inputs thereof to the source for generating positive and negative potentials at outputs thereof; phase sensitive demodulator means having a first input connected to a reference AC voltage source and a second input connected in circuit with the accelerometer to detect capacitive imbalances thereof; integrating means connected to the output of the demodulator means for generating a signal corresponding to the integral of the capacitive imbalance; feedback means connecting the integral signal to the movable plate; means connecting the fixed plates of the accelerometer to corresponding positive and negative potentials; and terminal means connected to the output of the integrating means for permitting measurement of the integral signal; wherein the reference AC voltage is derived from a terminal of a transformer, a secondary winding of the transformer being connected in circuit with fixed plates of the accelerometer.
Claim 10
Dependent Claim
168 words
A control signal for an electro-static capacitive accelerometer which includes two fixed plates and a movable intermediary plate, the circuits comprising: a reference source of DC power; means connected at the inputs thereof to the source for generating positive and negative potentials at outputs thereof; phase sensitive demodulator means having a first input connected to a reference AC voltage source and a second input connected in circuit with the accelerometer to detect capacitive imbalances thereof; integrating means connected to the output of the demodulator means for generating a signal corresponding to the integral of the capacitive imbalance; feedback means connecting the integral signal to the movable plate; means connecting the fixed plates of the accelerometer to corresponding positive and negative potentials; and terminal means connected to the output of the integrating means for permitting measurement of the integral signal; wherein the reference AC voltage is derived from a terminal of a transformer, a secondary winding of the transformer being connected in circuit with fixed plates of the accelerometer.
References Cited (Backward Citations)
US3151486A
Cited
US3446079A
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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) | 1985-10-11 | 1986-04-12 | 1986-10-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1989-10-11 | 1990-04-12 | 1990-10-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1993-10-11 | 1994-04-12 | 1994-10-12 | $7700.00 | Window Closed / Lapsed |