US3775679A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Apparatus and method for direct readout of capacitively gauged dimensions
Assignee: ADE Corp
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Filing: 1971-12-09
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Granted: 1973-11-27
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Expires: 1991-12-09
Abstract
Abstract An electronics system and method for processing the output of a dimension sensing capacitive gauge or probe having a measured capacitance between electrodes. Control of the capacitive gauge''s output through control of its excitation allows a parameter of the excitations output to be used as an indication directly proportional to a dimension, typically electrode separation, which varies inversely with the capacitance between the electrodes. An output from a second similar gauge is used to deflect a meter for a direct indication of the dimension. Alternatively a second excitation for the second gauge is provided with its output used to control the first excitation whereby the frequency ratio of the two excitations provides a direction indication of the dimension and is easily digitized. Environmentally induced changes in either gauge are balanced by proximity of the gauges and the excitation amplitude is regulated.
Inventors
- 👤 R Abbe
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 13:29
CPC Classifications
G; G01; G01B; G01B7/00; G01B7/12; G01B7/02; G01B7/023; G01B7/06; G01B7/08; G01R; G01R17/00
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
151 words
A method of electronically obtaining an output proportional to a physical dimension from a capacitance sensing distance gauge which operates by: a. applying an alternating electric excitation from a first source through a first measuring circuit across a first nonconducting gap etween a pair of first electric conductors having a physical dimension therebetween inversely varying with the capacitance between said first electric conductors; and b. deriving in said first measuring circuit a first signal from the response of said electric excitation across said first nonconducting gap, said first signal tending to vary with the capacitance between said first electric conductors, said method comprising the steps of: 1. controlling a parameter of the output oF said source to maintain said first signal equal to a control signal; and 2. developing a second signal varying with a parameter of the output of said source which second signal varies with the separation being sensed.
Claim 2
Independent Claim
151 words
A method of electronically obtaining an output proportional to a physical dimension from a capacitance sensing distance gauge which operates by: a. applying an alternating electric excitation from a first source through a first measuring circuit across a first nonconducting gap etween a pair of first electric conductors having a physical dimension therebetween inversely varying with the capacitance between said first electric conductors; and b. deriving in said first measuring circuit a first signal from the response of said electric excitation across said first nonconducting gap, said first signal tending to vary with the capacitance between said first electric conductors, said method comprising the steps of: 1. controlling a parameter of the output oF said source to maintain said first signal equal to a control signal; and 2. developing a second signal varying with a parameter of the output of said source which second signal varies with the separation being sensed.
Claim 3
Dependent Claim
84 words
The method of claim 1 wherein said control signal is constant and said step of developing said second signal is further characterized by the steps of: a. applying alternating electric excitation from said first source through a second measuring circuit across a second non-conducting gap between a pair of second electrical conductors; and b. deriving said second signal from the response of the alternating electric excitation across said second non-conducting gap, said second signal varying inversely with the capacitance between said first electric conductors.
Claim 4
Dependent Claim
23 words
developing a second signal varying with a parameter of the output of said source which second signal varies with the separation being sensed.
Claim 5
Dependent Claim
23 words
developing a second signal varying with a parameter of the output of said source which second signal varies with the separation being sensed.
Claim 6
Dependent Claim
124 words
The method of claim 1 wherein the parameter of the output of said source which is controlled is frequency and said step of developing said second signal further includes the steps of: a. applying alternating electric excitation from a second source through a second measuring circuit across a second non-conducting gap between a pair of second electric conductors; b. deriving in said second measuring circuit said control signal from the response of the alternating electric excitation to said second electric conductors; and c. counting the number of polarity reversals of the excitation from said first source during a selected number of polarity reversals of the excitation from said second source, the number counted being inversely proporational to the capacitance between said first electric conductors.
Claim 7
Dependent Claim
27 words
The method of claim 3 further including the step of maintaining the ratio of excitation amplitudes from said first and second sources equal to a preset number.
Claim 8
Dependent Claim
128 words
Apparatus for giving an output varying with the separation between a pair of first electric conductors comprising: a. a pair of first electric conductors with a non-conducting gap therebetween; b. a first source of alternating electric excitation; c. means for applying excitation from said first source across said first pair of electric conductors; d. means for deriving a first signal representative of the response of said first electric conductors to the excitation from said first source and tending to vary with the capacitance between said first electric conductors; e. means for controlling a parameter of the excitation of said first source to maintain said first signal equal to a control signal; and f. means for developing a second signal varying with the controlled parameter of said first source.
Claim 9
Dependent Claim
128 words
Apparatus for giving an output varying with the separation between a pair of first electric conductors comprising: a. a pair of first electric conductors with a non-conducting gap therebetween; b. a first source of alternating electric excitation; c. means for applying excitation from said first source across said first pair of electric conductors; d. means for deriving a first signal representative of the response of said first electric conductors to the excitation from said first source and tending to vary with the capacitance between said first electric conductors; e. means for controlling a parameter of the excitation of said first source to maintain said first signal equal to a control signal; and f. means for developing a second signal varying with the controlled parameter of said first source.
Claim 10
Dependent Claim
82 words
The apparatus of claim 5 wherein: a. said control signal is a constant value; and b. said means for developing said second signal further includes: i. means for applying excitation from said first source across a pair of second electric conductors separated by a non-conducting gap; and ii. means for deriving a second signal representative of the response of said second electric conductors to the excitation from said first source and tending to vary with the capacitance between said second electric conductors.
Claim 11
Dependent Claim
97 words
The apparatus of claim 5 wherein: a. said parameter controlled is frequency; and b. said means for developing said second signal further includes: i. a second source of alternating electric excitation; ii. means for deriving said control signal as a signal proportional to the excitation amplitude and frequency of said second source; and iii. means for counting the number of polarity reversals in the excitation from said first source during a selected number of polarity reversals of the excitation from said second source, the number counted being inversely proportional to the capacitance between said first electric conductors.
Claim 12
Dependent Claim
25 words
The apparatus of claim 7 further including means for maintaining the ratio of potentials from said first and second sources equal to a preset number.
Claim 13
Dependent Claim
62 words
The apparAtus of claim 5 further characterized by having: a. a first reference capacitance; b. means for applying excitation from said first source across said first reference capacitance, said first signal as derived by said means for deriving said first signal being representative of the difference in the response of said first reference capacitance and the capacitance between said first electrical conductors.
Claim 14
Dependent Claim
86 words
The apparatus of claim 9 wherein the parameter controlled is frequency and wherein said means for developing said second signal further includes: a. a second source of alternating electric excitation; b. a pair of comparison capacitances differing from each other by a finite capacitance; c. means for applying excitation from said second source to each of said pair of comparison capacitances; and d. means for deriving said control signal as a signal representative of the capacitance difference between the capacitances of said pair of comparison capacitances.
Claim 15
Dependent Claim
58 words
The apparatus of claim 10 wherein said means for developing a second signal further includes means for counting the number of polarity reversals of the excitation from said first source during a selected number of polarity reversals of the excitation from said second source, the number counted being inversely proportional to the capacitance between said first electric conductors.
Claim 16
Dependent Claim
25 words
The apparatus of claim 11 further including means for maintaining the ratio of amplitudes from said first and second soruces equal to a preset number.
Claim 17
Dependent Claim
162 words
The apparatus of claim 5 further characterized by having a first bridge composed of: a. first and second DC blocking impedances each connected electrically at one terminal thereof to a first excitation terminal of said first source; b. a first reference capacitance connected at one terminal both to one of said first electrical conductors and to the second excitation terminal of said source; c. means for conducting excitation from said first source through said first and second DC blocking impedances to the other terminal and other conductor respectively of said first reference capacitance and said first electrical conductors during one polarity of excitation from said first source and to the other conductor and other terminal respectively of said first electrical conductors and first reference capacitance during the other polarity; and d. means for conducting charge build-up across said DC blocking impedances to the second terminal of said first source, said first signal being the average current through said means for conducting charge.
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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) | 1976-11-26 | 1977-05-28 | 1977-11-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-11-26 | 1981-05-28 | 1981-11-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-11-26 | 1985-05-28 | 1985-11-27 | $7700.00 | Window Closed / Lapsed |