Patent US4924172A successfully refreshed from Google Patents.
US4924172A
Expired / Lapsed
US
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Capacitive sensor and electronic circuit for non-contact distance measurement
Assignee: KAMAN INSTRUMENTATION Corp 1500 GARDEN OF GODS ROAD COLORADO SPRINGS COLORADO 80933-7463 A CORP OF CT
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Filing: 1988-08-25
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Granted: 1990-05-08
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Expires: 2008-08-25
Abstract
Abstract A novel thin, three-terminal capacitive transducer which is positioned in a clearance gap to be measured is presented. This transducer comprises an insulated assembly having three parallel conductive planes with the first and second plane each containing a single electrode and the third plane containing a pair of spaced electrodes. Preferably, each electrode is composed of a thin layer of copper mounted on an insulated substrate such as an epoxy-glass composite. An air space is provided between each of the pair of electrodes in the third plane and the single electrode in the second plane. Another important feature of the present invention is a novel electronic circuit for use in conjunction with the novel three terminal capacitive transducer. This circuit provides a means of "synthetic resonance" whereby a small capacitance (such as generated by the three-terminal capacitive sensor of this invention) functions as if it were at or near series resonance with a synthesized large inductance. This is achieved by using a synthesized network (which is a variation of a known twin-tee circuit) in the feedback path of a high gain amplifier, thereby inverting the normal rejection notch into a resonance-like peak at a frequency determined mathematically.
Inventors
- 👤 William A. Holmgren
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 22:54
CPC Classifications
G; G01; G01B; G01B7/00; G01B7/14; G01D; G01D5/00; G01D5/12; G01D5/14; G01D5/24; G01D5/241; G01D5/2417
Claims Analysis
Total Claims: 39
Claim 1
Independent Claim
168 words
A capacitive sensor comprising: at least one pair of first electrode means, said first electrode means being spaced apart and being coplanar in a first plane; coupling plate means spaced from said pair of first electrode means in a second plane, said second plane being parallel to said first plane; ground plate means spaced from said coupling plate means in a third plane, said third plane being parallel to said first and second planes, and said second plane being sandwiched between said first and third planes; first dielectric material being positioned between said first electrode means and said coupling plate means; second dielectric material being positioned between said coupling plate means and said ground plate means; a first gap between one of said first electrode means and said coupling plate means; a second gap between the other of said first electrode means and said coupling plate means; and said coupling plate means being electrically isolated from said pair of first electrode means and from said ground plate means.
Claim 2
Dependent Claim
168 words
A capacitive sensor comprising: at least one pair of first electrode means, said first electrode means being spaced apart and being coplanar in a first plane; coupling plate means spaced from said pair of first electrode means in a second plane, said second plane being parallel to said first plane; ground plate means spaced from said coupling plate means in a third plane, said third plane being parallel to said first and second planes, and said second plane being sandwiched between said first and third planes; first dielectric material being positioned between said first electrode means and said coupling plate means; second dielectric material being positioned between said coupling plate means and said ground plate means; a first gap between one of said first electrode means and said coupling plate means; a second gap between the other of said first electrode means and said coupling plate means; and said coupling plate means being electrically isolated from said pair of first electrode means and from said ground plate means.
Claim 3
Dependent Claim
52 words
The sensor of claim 1 wherein: said first dielectric material comprises first and second pairs of discrete members, one pair of said members being associated with each of said first electrodes; said first gap residing between said first pair of members; and said second gap residing between said second pair of members.
Claim 4
Dependent Claim
14 words
The sensor of claim 1 wherein: said first and second gaps are air gaps.
Claim 5
Dependent Claim
14 words
The sensor of claim 2 wherein: said first and second gaps are air gaps.
Claim 6
Dependent Claim
17 words
The sensor of claim 1 wherein: said first and second dielectric material is comprised of epoxy-glass composite.
Claim 7
Dependent Claim
17 words
The sensor of claim 2 wherein: said first and second dielectric material is comprised of epoxy-glass composite.
Claim 8
Dependent Claim
19 words
The sensor of claim 1 wherein: said first electrode means, coupling plate means and ground plate means comprise copper.
Claim 9
Dependent Claim
33 words
The sensor of claim 1 wherein: a channel is defined between said spaced apart pair of first electrode means, said channel being defined by said first dielectric material and said coupling plate means.
Claim 10
Dependent Claim
33 words
The sensor of claim 2 wherein: a channel is defined between said spaced apart pair of first electrode means, said channel being defined by said first dielectric material and said coupling plate means.
Claim 11
Dependent Claim
49 words
The sensor of claim 1 including: a first coaxial cable connected to said one of said pair of first electrode means and to said ground plate means; and a second coaxial cable connected to the other of said pair of first electrode means and to said ground plate means.
Claim 12
Dependent Claim
24 words
The sensor of claim 10 including: electronic circuit means communicating with said first and second coaxial cables for measuring the distance between two boundaries.
Claim 13
Dependent Claim
56 words
An electronic circuit for creating synthetic resonance comprising: an inductive parallel tee network; and high gain amplifier means, said inductive parallel tee network electrically communicating with the feedback path of said high gain amplifier means to thereby invert the rejection notch of said inductive parallel tee network into a synthesized resonance peak at a predetermined frequency.
Claim 14
Dependent Claim
56 words
An electronic circuit for creating synthetic resonance comprising: an inductive parallel tee network; and high gain amplifier means, said inductive parallel tee network electrically communicating with the feedback path of said high gain amplifier means to thereby invert the rejection notch of said inductive parallel tee network into a synthesized resonance peak at a predetermined frequency.
Claim 15
Dependent Claim
22 words
The circuit of claim 12 wherein: said high gain amplifier means comprises a first amplifier connected in series to a second amplifier.
Claim 16
Dependent Claim
167 words
The circuit of claim 12 wherein said inductive parallel tee network comprises: a first tee branch having a first input arm, a first output arm and a first middle leg between said first input and output arms, and including a first input capacitance C on said first input arm, a first output resistance R on said first output arm and a first grounded variable capacitance C 1 on said first middle leg; a second tee branch having a second input arm, a second output arm and a second middle leg between said second input and output arms, and including a second input capacitance C 2 on said second input arm, a second output capacitance C 3 on said second output arm and an inductance L on said second middle leg; and a loop comprising a resistance R p electrically communicating with a variable capacitance C o , said loop electrically communicating between second input arm capacitance C 2 and said second output arm capacitance C 3 .
Claim 17
Dependent Claim
13 words
The circuit of claim 14 wherein said predetermined frequency is derived by: ##EQU9##
Claim 18
Dependent Claim
22 words
The circuit of claim 14 wherein: said high gain amplifier means comprises a first amplifier connected in series to a second amplifier.
Claim 19
Dependent Claim
37 words
The circuit of claim 16 including: a first resistance R 2 , a second resistance R 3 and a third resistance R 4 all connected in series and being electrically responsive to said first and second amplifier.
Claim 20
Dependent Claim
37 words
The circuit of claim 13 including: a first resistance R 2 , a second resistance R 3 and a third resistance R 4 all connected in series and being electrically responsive to said first and second amplifier.
Claim 21
Dependent Claim
175 words
The circuit of claim 12 wherein said inductive parallel tee network comprises: a first tee branch having a first input arm, a first output arm and a first middle leg between said first input and output arms, and including a first input variable capacitance C on said first input arm, a first output variable resistance R on said first output arm and a first capacitance C 1 on said first middle leg; a second tee branch having a second input arm, a second output arm and a second middle leg between said second input and output arms, and including a second input capacitance C 2 on said second input arm, a second output capacitance C 3 on said second output arm, an inductance L connected in series to a resistance R i and a resistance R s , said inductance L, resistance R i and resistance R s all on said second middle leg; and a resistance R p electrically communicating between said second input arm and said second middle leg resistance R s .
Claim 22
Dependent Claim
22 words
The circuit of claim 19 wherein: said high gain amplifier means comprises a first amplifier connected in series to a second amplifier.
Claim 23
Dependent Claim
37 words
The circuit of claim 20 including: a first resistance R 2 , a second resistance R 3 and a third resistance R 4 all connected in series and being electrically responsive to said first and second amplifier.
Claim 24
Dependent Claim
13 words
The circuit of claim 19 wherein said predetermined frequency is derived by: ##EQU10##
Claim 25
Dependent Claim
14 words
The circuit of claim 19 wherein: said variable capacitance C comprises a capacitive sensor.
Claim 26
Dependent Claim
155 words
The circuit of claim 23 wherein said capacitive sensor comprises: at least one pair of first electrode means, said first electrode means being spaced apart and being coplanar in a first plane; coupling plate means spaced from said pair of first electrode means in a second plane, said second plane being parallel to said first plane; ground plate means spaced from said coupling plate means in a third plane, said third plane being parallel to said first and second planes, and said second plane being sandwiched between said first and third planes; first dielectric material being positioned between said first electrode means and said coupling plate means; second dielectric material being positioned between said coupling plate means and said ground plate means; a first gap between said one of said first electrode means and said coupling plate means; and a second gap between the other of said first electrode means and said coupling plate means.
Claim 27
Dependent Claim
52 words
The sensor of claim 24 wherein: said first dielectric material comprises first and second pairs of discrete members, one pair of said members being associated with each of said first electrodes; said first gap residing between said first pair of members; and said second gap residing between said second pair of members.
Claim 28
Dependent Claim
33 words
The sensor of claim 24 wherein: a channel is defined between said spaced apart pair of first electrode means, said channel being defined by said first dielectric material and said coupling plate means.
Claim 29
Dependent Claim
49 words
The sensor of claim 24 including: a first coaxial cable connected to said one of said pair of first electrode means and to said ground plate means; and a second coaxial cable connected to the other of said pair of first electrode means and to said ground plate means.
Claim 30
Dependent Claim
193 words
A capacitive sensor comprising: at least one pair of first electrode means, said first electrode means being spaced apart and being coplanar in a first plane; coupling plate means spaced from said pair of first electrode means in a second plane, said second plane being parallel to said first plane; ground plate means spaced from said coupling plate means in a third plane, said third plane being parallel to said first and second planes, and said second plane being sandwiched between said first and third planes; first dielectric material being positioned between said first electrode means and said coupling plate means; second dielectric material being positioned between said coupling plate means and said ground plate means; a first gap between one of said first electrode means and said coupling plate means; a second gap between the other of said first electrode means and said coupling plate means; said first dielectric material comprising first and second pairs of discrete members, one pair of said members being associated with each of said first electrodes; said first gap residing between said first pair of members; and said second gap residing between said second pair of members.
Claim 31
Dependent Claim
193 words
A capacitive sensor comprising: at least one pair of first electrode means, said first electrode means being spaced apart and being coplanar in a first plane; coupling plate means spaced from said pair of first electrode means in a second plane, said second plane being parallel to said first plane; ground plate means spaced from said coupling plate means in a third plane, said third plane being parallel to said first and second planes, and said second plane being sandwiched between said first and third planes; first dielectric material being positioned between said first electrode means and said coupling plate means; second dielectric material being positioned between said coupling plate means and said ground plate means; a first gap between one of said first electrode means and said coupling plate means; a second gap between the other of said first electrode means and said coupling plate means; said first dielectric material comprising first and second pairs of discrete members, one pair of said members being associated with each of said first electrodes; said first gap residing between said first pair of members; and said second gap residing between said second pair of members.
Claim 32
Dependent Claim
14 words
The sensor of claim 28 wherein: said first and second gaps are air gaps.
Claim 33
Dependent Claim
17 words
The sensor of claim 28 wherein: said first and second dielectric material is comprised of epoxy-glass composite.
Claim 34
Dependent Claim
33 words
The sensor of claim 28 wherein: a channel is defined between said spaced apart pair of first electrode means, said channel being defined by said first dielectric material and said coupling plate means.
Claim 35
Dependent Claim
150 words
A capacitive sensor comprising: at least one pair of first electrode means, said first electrode means being space apart and being coplanar in a first plane; coupling plate means spaced from said pair of first electrode means in a second plane, said second plane being parallel to said first plane; ground plate means spaced from said coupling plate means in a third plane, said third plane being parallel to said first and second planes, and said second plane being sandwiched between said first and third planes; first dielectric material being positioned between said first electrode means and said coupling plate means; second dielectric material being positioned between said coupling plate means and said ground plate means; a first air gap between one of said first electrode means and said coupling plate means; and a second air gap between the other of said first electrode means and said coupling plate means.
Claim 36
Dependent Claim
150 words
A capacitive sensor comprising: at least one pair of first electrode means, said first electrode means being space apart and being coplanar in a first plane; coupling plate means spaced from said pair of first electrode means in a second plane, said second plane being parallel to said first plane; ground plate means spaced from said coupling plate means in a third plane, said third plane being parallel to said first and second planes, and said second plane being sandwiched between said first and third planes; first dielectric material being positioned between said first electrode means and said coupling plate means; second dielectric material being positioned between said coupling plate means and said ground plate means; a first air gap between one of said first electrode means and said coupling plate means; and a second air gap between the other of said first electrode means and said coupling plate means.
Claim 37
Dependent Claim
191 words
A capacitive sensor comprising: at least one pair of first electrode means, said first electrode means being spaced apart and being coplanar in a first plane; coupling plate means spaced from said pair of first electrode means in a second plane, said second plane being parallel to said first plane; ground plate means spaced from said coupling plate means in a third plane, said third plane being parallel to said first and second planes, and said second plane being sandwiched between said first and third planes; first dielectric material being positioned between said first electrode means and said coupling plate means; second dielectric material being positioned between said coupling plate means and said ground plate means; a first gap between one of said first electrode means and said coupling plate means; a second gap between the other of said first electrode means and said coupling plate means; and a first coaxial cable connected to said one of said pair of first electrode means and to said ground plate means; and a second coaxial cable connected to the other of said pair of first electrode means and to said ground plate means.
Claim 38
Dependent Claim
191 words
A capacitive sensor comprising: at least one pair of first electrode means, said first electrode means being spaced apart and being coplanar in a first plane; coupling plate means spaced from said pair of first electrode means in a second plane, said second plane being parallel to said first plane; ground plate means spaced from said coupling plate means in a third plane, said third plane being parallel to said first and second planes, and said second plane being sandwiched between said first and third planes; first dielectric material being positioned between said first electrode means and said coupling plate means; second dielectric material being positioned between said coupling plate means and said ground plate means; a first gap between one of said first electrode means and said coupling plate means; a second gap between the other of said first electrode means and said coupling plate means; and a first coaxial cable connected to said one of said pair of first electrode means and to said ground plate means; and a second coaxial cable connected to the other of said pair of first electrode means and to said ground plate means.
Claim 39
Dependent Claim
24 words
The sensor of claim 33 including: electronic circuit means communicating with said first and second coaxial cables for measuring the distance between two boundaries.
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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) | 1993-05-07 | 1993-11-06 | 1994-05-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-05-07 | 1997-11-06 | 1998-05-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-05-07 | 2001-11-06 | 2002-05-08 | $7700.00 | Window Closed / Lapsed |