US3609580A
Expired / Lapsed
US
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Electrical sensing apparatus
Assignee: Westinghouse Electric Corp
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Filing: 1969-11-14
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Granted: 1971-09-28
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Expires: 1989-11-14
Abstract
Abstract Electrical sensing apparatus such as proximity detectors and vibration pickups of the type in which the instantaneous displacement between an inductor in the tank circuit of an oscillator and a conductive object in the field of the inductor is reflected in the output amplitude of the oscillator as a function of the ''''Q'''' of the tank circuit. The oscillator incorporates a low frequency, essentially direct current negative feedback path which, in conjunction with high loop gain at oscillation frequencies, insures that the circuit will oscillate under low ''''Q'''' conditions when the inductor is closely adjacent a conductive object.
Inventors
- 👤 Francis T Thompson
- 👤 Bruce R Dow
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 09:26
CPC Classifications
H; H03; H03K; H03K17/00; H03K17/28; H03K17/288; G; G01; G01H; G01H1/00; G01H1/10; G01V; G01V3/00; G01V3/08; G01V3/10; G01V3/101; G01V3/102; H03K17/94; H03K17/945; H03K17/95; H03K17/952; H03K17/9537; H03K17/9542; H03K17/9547; H03K17/955
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
90 words
In electrical sensing apparatus, the combination of an oscillatory circuit including an amplifying device, a tuned circuit for said amplifying device, an inductance in said tuned circuit adapted to be placed in close proximity to a metallic object whose distance from the inductance is to be determined, a positive feedback path for said amplifying device connected to said tuned circuit, and a negative feedback path for said amplifying device for insuring that said amplifying device will be in its linear region of operation at all times and will support oscillations.
Claim 2
Dependent Claim
90 words
In electrical sensing apparatus, the combination of an oscillatory circuit including an amplifying device, a tuned circuit for said amplifying device, an inductance in said tuned circuit adapted to be placed in close proximity to a metallic object whose distance from the inductance is to be determined, a positive feedback path for said amplifying device connected to said tuned circuit, and a negative feedback path for said amplifying device for insuring that said amplifying device will be in its linear region of operation at all times and will support oscillations.
Claim 3
Dependent Claim
28 words
The electrical sensing apparatus of claim 1 including means for eliminating high-frequency signal components in said negative feedback path, having only a low frequency, essentially direct current signal.
Claim 4
Dependent Claim
22 words
The electrical sensing apparatus of claim 2 wherein said means for eliminating comprises a capacitor connecting said negative feedback path to ground.
Claim 5
Dependent Claim
18 words
The electrical sensing apparatus of claim 1 wherein said tuned circuit includes both said inductor and a capacitor.
Claim 6
Dependent Claim
23 words
The electrical sensing apparatus of claim 1 wherein said amplifying device comprises a pair of electron valves connected to a differential amplifier configuration.
Claim 7
Dependent Claim
36 words
The electrical sensing apparatus of claim 3 wherein said electron valves are provided with control electrodes and said positive and negative feedback paths are connected to the control electrode of only one of said electron valves.
Claim 8
Dependent Claim
41 words
The electrical sensing apparatus of claim 1 wherein said electron valves are provided with control electrodes, said positive feedback path being connected to one of said control electrodes and said negative feedback path being connected to the other of said electrodes.
Claim 9
Dependent Claim
14 words
The electrical sensing apparatus of claim 6 wherein said electron valves comprise field-effect transistors.
Claim 10
Dependent Claim
13 words
The electrical sensing apparatus of claim 7 wherein said electron valves comprise transistors.
Claim 11
Dependent Claim
39 words
The electrical sensing apparatus of claim 1 wherein said tuned circuit is connected to a switched constant current source whereby the positive feedback voltage in said positive feedback path will vary linearly with the Q of said tuned circuit.
Claim 12
Dependent Claim
18 words
The electrical sensing apparatus of claim 1 including rectifier means for demodulating oscillations produced by said oscillatory circuit.
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) | 1974-09-27 | 1975-03-29 | 1975-09-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-09-27 | 1979-03-29 | 1979-09-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-09-27 | 1983-03-29 | 1983-09-28 | $7700.00 | Window Closed / Lapsed |