US3694741A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Coupled inductance impedance measuring circuit with increased sensitivity and frequency independence
Assignee: ADE Corp
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Filing: 1970-10-28
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Granted: 1972-09-26
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Expires: 1990-10-28
Abstract
Abstract An impedance measuring circuit having two closely coupled inductances conducting alternating electric excitation from a grounded source through measuring and balancing impedance branches respectively to ground. Peak detection circuitry referenced to ground in the impedance measuring circuit gives an indication of the difference in the voltage across the measuring and balancing impedances. Where measuring and balancing impedances are capacitive reactances and at source frequencies above resonance of the inductance-capacitance circuit, substantial frequency independence is achieved.
Inventors
- 👤 Robert C Abbe
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 01:31
CPC Classifications
G; G01; G01R; G01R27/00; G01R27/02; G01R17/00
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
172 words
A measurement circuit for quantities related to a pair of like sign impedances comprising: a source of excitation frequency; a bridge circuit including said first pair of like sign impedances in adjacent arms of said bridge and a coupled pair like sign inductors in the other adjacent arms of said bridge, said two pairs being of opposite sign and resonant at a frequency below the frequency of said source; means for exciting said bridge circuit from said source at the junctions of said like sign impedances; and a measurement circuit adapted to measure with respect to ground signals at each of the junctions between said pair of like sign impedances and said pair of coupled inductors; said coupled inductors producing low source impedance for signal components at said junctions between said two pairs for current flow in said measurement circuit and due to bridge unbalance, said measurement circuit producing from said signal components additive ground referenced signals which are substantially independent of frequency at source frequencies above resonance for said bridge circuit.
Claim 2
Dependent Claim
172 words
A measurement circuit for quantities related to a pair of like sign impedances comprising: a source of excitation frequency; a bridge circuit including said first pair of like sign impedances in adjacent arms of said bridge and a coupled pair like sign inductors in the other adjacent arms of said bridge, said two pairs being of opposite sign and resonant at a frequency below the frequency of said source; means for exciting said bridge circuit from said source at the junctions of said like sign impedances; and a measurement circuit adapted to measure with respect to ground signals at each of the junctions between said pair of like sign impedances and said pair of coupled inductors; said coupled inductors producing low source impedance for signal components at said junctions between said two pairs for current flow in said measurement circuit and due to bridge unbalance, said measurement circuit producing from said signal components additive ground referenced signals which are substantially independent of frequency at source frequencies above resonance for said bridge circuit.
Claim 3
Dependent Claim
19 words
The circuit of claim 1 in which said pair of like impedances related to said quantities are capacitive reactances.
Claim 4
Dependent Claim
66 words
The circuit of claim 2 further comprising: an indicator; means for applying a signal representing the excited response of one of said capacitive reactances to said indicator during one polarity of excitation to said measuring impedance; and means for applying a signal representative of the response of the other of said capacitive reactances to said indicator, during the opposite polarity of excitation to said balancing impedance.
Claim 5
Dependent Claim
47 words
The circuit of claim 3 further comprising: means responsive to the peak magnitude of the responses of said capacitive reactances during the respective polarities of excitation producing the responses applied to said indicator; and means for applying to said indicator a signal intermediate to said peak magnitudes.
Claim 6
Dependent Claim
64 words
The circuit of claim 3 further comprising means responsive to the peak magnitude of the responses of said capacitive reactances during the respective polarities of excitation producing the responses applied to said indicator, wherein said excited responses and peak detected responses are of opposite polarity, and wherein said indicator comprises differential signal processing means responsive to the effective sum of said peak detected responses.
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) | 1975-09-26 | 1976-03-27 | 1976-09-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-09-26 | 1980-03-27 | 1980-09-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-09-26 | 1984-03-27 | 1984-09-26 | $7700.00 | Window Closed / Lapsed |