US3784897A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Capacitor transducer
Assignee: Landis Tool Co
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Filing: 1972-02-17
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Granted: 1974-01-08
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Expires: 1992-02-17
Abstract
Abstract A capacitive transducer in which a pair of exciter electrodes connected to an AC source are disposed in common planes to present a gap. A pick-off electrode is disposed in another plane and extends on either side of the gap. A conductive screen is interposed between the exciter electrodes and the pick-off electrode and is connected to ground potential so as to block capacitive coupling between the exciter electrodes and the pickoff electrode except as between discrete areas of the exciter electrodes and an opposite area of the pick-off electrode exposed or coupled through an aperture in the screen.
Inventors
- 👤 G Norrie
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 18:32
CPC Classifications
G; G01; G01D; G01D5/00; G01D5/12; G01D5/14; G01D5/24; G01D5/241; G01D5/2412; G01D5/2415; H; H04; H04R; H04R19/00
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
230 words
In a capacitive transducer, the combination comprising: first and second exciter electrodes fixedly located in a common plane and having adjacent spaced-apart edges defining an electrical discontinuity therebetween, a pick-off electrode fixedly located adjacent said first and second exciter electrodes in spaced relation from the common plan thereof and spanning the electrical discontinuity therebetween, means for connecting said first and second exciter electrodes to sources of different potential to induce a signal on said pickoff electrode indicative of the portions of said first and second electrodes spanned by said pick-off electrode, a shield located between said pick-off electrode and said first and second exciter elecrodes and connected to a ground potential to prevent a signal from being induced on said pickoff electrode, said shield having a dielectric aperture therein bridging the electrical discontinuity for permitting portions of said first and second exciter electrodes adjacent the electrical discontinuity to induce a signal on said pick-off electrode, said shield being movable relative to said first and second exciter electrodes about the electrical discontinuity to vary the portions of said first and second exciter elements inducing a signal on said pick-off electrode to produce a signal responsive to the position of said movable shield, and said shield being dimensioned to prevent stray capacitive coupling between said pick-off electrode and said first and second exciter electrodes at all positions of movement of said shield.
Claim 2
Dependent Claim
230 words
In a capacitive transducer, the combination comprising: first and second exciter electrodes fixedly located in a common plane and having adjacent spaced-apart edges defining an electrical discontinuity therebetween, a pick-off electrode fixedly located adjacent said first and second exciter electrodes in spaced relation from the common plan thereof and spanning the electrical discontinuity therebetween, means for connecting said first and second exciter electrodes to sources of different potential to induce a signal on said pickoff electrode indicative of the portions of said first and second electrodes spanned by said pick-off electrode, a shield located between said pick-off electrode and said first and second exciter elecrodes and connected to a ground potential to prevent a signal from being induced on said pickoff electrode, said shield having a dielectric aperture therein bridging the electrical discontinuity for permitting portions of said first and second exciter electrodes adjacent the electrical discontinuity to induce a signal on said pick-off electrode, said shield being movable relative to said first and second exciter electrodes about the electrical discontinuity to vary the portions of said first and second exciter elements inducing a signal on said pick-off electrode to produce a signal responsive to the position of said movable shield, and said shield being dimensioned to prevent stray capacitive coupling between said pick-off electrode and said first and second exciter electrodes at all positions of movement of said shield.
Claim 3
Dependent Claim
50 words
A capacitive transducer as defined in claim 1 wherein said exciter electrodes each are of tubular form and are disposed in end-to-end spaced relation to define said electrical discontinuity and wherein said shield has electrically conductive portions of tubular configuration located in end-to-end spaced relation to define said dielectric region.
Claim 4
Dependent Claim
60 words
A capacitive transducer as defined in claim 2 including a tubular housing within which said exciter electrodes are fixed, said pick-off electrode being in the form of an elongated sleeve concentrically disposed with respect to said exciter electrodes, and said shield being of a length to completely mask said exciter electrodes from said pick-off electrode except through said dielectric region.
Claim 5
Dependent Claim
35 words
A capacitive transducer as defined in claim 3 including a support assembly located axially within said housing and concentrically locating said pick-off electrode therewithin, and means for slidably supporting said shield on said support assembly.
Claim 6
Dependent Claim
40 words
A capacitive transducer as defined in claim 4 including a guide member disposed diametrically within said housing, said shield having slots formed therein for slidably receiving said guide member to prevent rotation of said shield means relative to said housing.
Claim 7
Dependent Claim
25 words
A capacitive transducer as defined in claim 1 wherein said pick-off electrode, said exciter electrodes and said shield are in the form of flat plates.
Claim 8
Dependent Claim
54 words
A capacitive transducer as defined in claim 1 wherein said exciter electrodes are each of annular form and having zig-zag edge portions disposed in spaced relation to define said electrical discontinuity, said pick-off electrode being concentrically disposed with respect to said exciter electrodes, and said shield being rotatable between said exciter and pick-off electrodes.
Claim 9
Dependent Claim
31 words
A capacitive transducer as defined in claim 1 wherein the electrical discontinuity defined by the adjacent edges of said first and second exciter electrodes is a straight gap of uniform width.
Claim 10
Dependent Claim
31 words
A capacitive transducer as defined in claim 1 wherein the electrical discontinuity defined by the adjacent edges of said first and second exciter electrodes is a saw-tooth gap of uniform width.
Claim 11
Dependent Claim
36 words
A capacitive transducer as claimed in claim 1 including a compensatory electrode means positioned near one of said exciter electrodes and separated therefrom by a gap, said compensatory electrode means being coupled to said pick-off electrode.
Claim 12
Dependent Claim
37 words
A capacitive trasducer as claimed in claim 10 including a second compensatory electrode positioned near the other of said exciter electrodes and separated therefrom by a gap, said second compensatory electrode being coupled to said pick-off electrode.
Claim 13
Dependent Claim
26 words
A capacitive transducer as claimed in claim 11 including means for varying the coupling between at least one of said compensatory electrodes and said pick-off electrode.
Claim 14
Dependent Claim
39 words
A capacitive transducer as defined in claim 1 including a second pair of exciter electrodes defining a second electrical discontinuity therebetween, a second pick-off electrode, and said shield having a second dielectric aperture therein bridging said second electrical discontinuity.
Claim 15
Dependent Claim
31 words
A capacitive transducer as defined in claim 13 wherein the electrical discontinuity defined by the adjacent edges of said first and second exciter electrodes is a saw-tooth gap of uniform width.
Claim 16
Dependent Claim
36 words
A capacitive transducer as claimed in claim 14 including a compensatory elecrode means positioned near one of said exciter electrodes and separated therefrom by a gap, said compensatory electrode means being coupled to said pickoff electrode.
Claim 17
Dependent Claim
37 words
A differential capacitor as claimed in claim 15 including a second compensatory electrode positioned near the other of said exciter electrodes and separated therefrom by a gap, said second compensatory electrode being coupled to said pick-off electrode.
Claim 18
Dependent Claim
104 words
A capacitive transducer as defined in claim 1 wherein the electrical discontinuity defined by the adjacent edges of said first and second exciter electrodes is a zig-zag gap along the path of relative movement between said shield and said exciter electrodes, and further including a second pick-off electrode and a second pair of exciter electrodes associated therewith, said second pair of exciter electrodes having adjacent edges defining a second electrical discontinuity therebetween extending at an acute angle of said path of relative movement, and said shield defining a second dielectric aperture therein bridging the second electrical discontinuity between said second pair of exciter electrodes.
Claim 19
Dependent Claim
36 words
A differential capacitor as claimed in claim 17 including a compensatory electrode means positioned near one of said exciter electrodes and separated therefrom by a gap, said compensatory electrode means being coupled to said pick-off electrode.
Claim 20
Dependent Claim
37 words
A differential capacitor as claimed in claim 18 including a second compensatory electrode positioned near the other of said exciter electrodes and separated therefrom by a gap, said second compensatory electrode being coupled to said pick-off electrode.
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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) | 1977-01-07 | 1977-07-09 | 1978-01-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-01-07 | 1981-07-09 | 1982-01-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-01-07 | 1985-07-09 | 1986-01-08 | $7700.00 | Window Closed / Lapsed |