Patent US3668672A successfully refreshed from Google Patents.
US3668672A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Capacitive transducer
Assignee: Ametek Inc
•
Filing: 1970-11-13
•
Granted: 1972-06-06
•
Expires: 1990-11-13
Abstract
Abstract A variable capacitance displacement transducer is disclosed for developing an electrical signal having an amplitude precisely controlled by the position of a mechanical input element, which in turn varies the capacitance of the transducer. The transducer includes three spaced conductive places arranged in parallel relation. Electrical signals are applied to one of the outer plates. The other two plates are maintained at substantially the same signal level for minimizing the capacitance therebetween so that the center plate functions as a shield to control the capacitive coupling between the two outer plates. An amplifier including a negative feedback circuit is coupled to the other outer plate to develop output signals having amplitudes determined by relative position between the inner plate and the two outer plates.
Inventors
- 👤 James A Parnell
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 09:21
CPC Classifications
G; G08; G08C; G08C19/00; G08C19/02; G08C19/10; G01; G01D; G01D5/00; G01D5/12; G01D5/14; G01D5/24; G01D5/2403
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
159 words
An apparatus for converting a displacement to an electrical signal, comprising: a first conductive element for connection to a source of input electrical signals; a second conductive element disposed in close proximity to the first conductive element; a third conductive element disposed between the first and second conductive elements to function as a capacitance shield between the first and second conductive elements; first means for maintaining the second and third conductive elements at substantially the same signal potential; second means for providing relative movement between the second and third conductive elements in response to the displacement to be converted to an electrical signal so that the third conductive element functions as a shield to vary the capacitance between the first and second conductive elements; and circuit means coupled to the second element for developing an electrical signal at an output as a function of the relative movement between the second and third conductive elements in response to the displacement.
Claim 2
Independent Claim
159 words
An apparatus for converting a displacement to an electrical signal, comprising: a first conductive element for connection to a source of input electrical signals; a second conductive element disposed in close proximity to the first conductive element; a third conductive element disposed between the first and second conductive elements to function as a capacitance shield between the first and second conductive elements; first means for maintaining the second and third conductive elements at substantially the same signal potential; second means for providing relative movement between the second and third conductive elements in response to the displacement to be converted to an electrical signal so that the third conductive element functions as a shield to vary the capacitance between the first and second conductive elements; and circuit means coupled to the second element for developing an electrical signal at an output as a function of the relative movement between the second and third conductive elements in response to the displacement.
Claim 3
Independent Claim
188 words
An apparatus for converting a displacement to an electrical signal, comprising: a first conductive element for connection to a source of input electrical signals; a second conductive element disposed in close proximity to the first conductive element; a third conductive element disposed between the first and second conductive elements to function as a capacitance shield between said first and second conductive elements; first means for maintaining the third conductive element at a substantially lower signal level than the level of the input electrical signals; second means for providing relative movement between said third conductive element and at least one of said first and second conductive elements in response to the displacement to be converted to an electrical signal so that said third conductive element functions as a shield to vary the capacitance between said first and second conductive elements; and circuit means coupled to the second conductive element for developing an electrical signal as a function of such relative movement in response to the displacement, and including means for maintaining the signal level on the second conductive element at substantially the signal level of said third conductive element.
Claim 4
Independent Claim
188 words
An apparatus for converting a displacement to an electrical signal, comprising: a first conductive element for connection to a source of input electrical signals; a second conductive element disposed in close proximity to the first conductive element; a third conductive element disposed between the first and second conductive elements to function as a capacitance shield between said first and second conductive elements; first means for maintaining the third conductive element at a substantially lower signal level than the level of the input electrical signals; second means for providing relative movement between said third conductive element and at least one of said first and second conductive elements in response to the displacement to be converted to an electrical signal so that said third conductive element functions as a shield to vary the capacitance between said first and second conductive elements; and circuit means coupled to the second conductive element for developing an electrical signal as a function of such relative movement in response to the displacement, and including means for maintaining the signal level on the second conductive element at substantially the signal level of said third conductive element.
Claim 5
Dependent Claim
55 words
The apparatus for converting the displacement to the electrical signal, as defined in claim 2, wherein the first means for maintaining the third conductive element at a substantially lower signal level than the level of the input electrical signals comprises means providing a reference of zero signal level electrically coupled to the third conductive element.
Claim 6
Dependent Claim
45 words
The apparatus for converting the displacement to the electrical signal, as defined in claim 2, wherein the circuit means coupled to the second conductive element develops an electrical signal having an amplitude varying as a function of the relative movement of the third conductive element.
Claim 7
Dependent Claim
62 words
The apparatus for converting the displacement to the electrical signal, as defined in claim 2, wherein the circuit means includes an amplifier having a capacitive element in a negative feedback circuit, the second conductive element being coupled to the input of the amplifier circuit so that the second conductive elemenT is maintained at substantially the signal level of said third conductive element.
Claim 8
Dependent Claim
32 words
The apparatus as defined in claim 2, wherein said first conductive element is connected to a source of input electrical signals which provides regulated input signals of a substantially square wave form.
Claim 9
Dependent Claim
27 words
The apparatus as defined in claim 2, wherein one of said first and second conductive elements has a width which varies as a function of relative movement.
Claim 10
Dependent Claim
25 words
The apparatus as defined in claim 2, wherein said first means comprises an amplifier coupled between the second conductive element and the third conductive element.
Claim 11
Dependent Claim
35 words
Apparatus as defined in claim 8, wherein said first means includes a unity gain amplifier having its input circuit connected to said second conductive element and its output circuit connected to said third conductive element.
Claim 12
Dependent Claim
35 words
The apparatus for converting the displacement to the electrical signal, as defined in claim 2, wherein the first, second and third conductive elements are disposed substantially parallel to each other, and are substantially flat plates.
Claim 13
Dependent Claim
83 words
The apparatus as defined in claim 10, wherein said means for maintaining the signal level of the second conductive element at substantially the signal level of said third conductive element comprises means for providing an effective capacitance in shunt with the capacitance between the second and third conductive elements, the effective capacitance being sufficiently larger than the capacitance between the second and third conductive elements so that the second conductive element is maintained at substantially the signal level of said third conductive element.
Claim 14
Dependent Claim
117 words
The apparatus as defined in claim 10, wherein: one of said first and second conductive elements, comprises the shape of a circular disc, the other of said first and second conductive elements, comprises a shape defined by the area between two radial arcs, said third conductive element comprising a substantially circular sector, said first and second conductive elements are stationarily mounted about a line passing substantially through the center of said circular disc, the center of said radial arcs, and the center of said third conductive element, and said means for providing said relative movement includes means for rotating said third conductive element in substantially parallel relation with said first and second conductive elements about said line.
References Cited (Backward Citations)
US2246928A
Cited
US2527215A
Cited
US2911638A
Cited
US3296522A
Cited
US3256482A
Cited
US3323046A
Cited
US3312892A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-06-06 | 1975-12-06 | 1976-06-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-06-06 | 1979-12-06 | 1980-06-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-06-06 | 1983-12-06 | 1984-06-06 | $7700.00 | Window Closed / Lapsed |