Patent US3706919A successfully refreshed from Google Patents.
US3706919A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Capacitive gauge
Assignee: ADE Corp
•
Filing: 1970-08-17
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Granted: 1972-12-19
•
Expires: 1990-08-17
Abstract
Abstract A capacitive probe having at least two electrically conducting probe tips or electrodes centrally placed within an electrically conducting housing and axially displaced from each other within the housing. A physical dimension is measured by determining the capacitance between one probe tip and a surface, the capacitance therebetween varying with the dimension being measured. Precise machining of planar probe tips and assemblies to make them identical, their close placement, and the use of a moisture impenetrable dielectric for supporting the tips within the housing insure precision measurement and environmental independence. This precision and its maintenance is augmented by electronic excitation circuitry for the probe tips which maintain the instantaneous electric potential on each tip approximately equal and which gives an output signal whose average variation from a ground or common potential is directly indicative of the distance being gauged. Modifications to the basic probe construction include: provisions for guarding each probe tip with a substantially equal potential: thin or thick film deposition probe tip constructions; and probes having a plurality of tips for sensing a multiplicity of factors influencing the capacitance between the probe and a surface with circuits for separating the factors. A specific application of this for dielectric strip width measurement is presented.
Inventors
- 👤 Robert C Abbe
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 18:16
CPC Classifications
G; G01; G01B; G01B7/00; G01B7/02; G01B7/023; G01R; G01R27/00; G01R27/02
Claims Analysis
Total Claims: 68
Claim 1
Independent Claim
110 words
A capacitive probe for use in a dimension measuring gauge comprising: a. an electrically conductive housing having an opening; b. at least one measuring electrode; c. means for supporting each said measuring electrode within and insulating it from said housing near the opening of said housing; d. at least one balancing electrode corresponding to each said measuring electrode and being of substantially the same size as its corresponding measuring electrode; and, e. means for supporting each said balancing electrode within and for insulating it from said housing; said means for supporting each said balancing electrode being of substantially the same size as said means for supporting its corresponding measuring electrode.
Claim 2
Dependent Claim
110 words
A capacitive probe for use in a dimension measuring gauge comprising: a. an electrically conductive housing having an opening; b. at least one measuring electrode; c. means for supporting each said measuring electrode within and insulating it from said housing near the opening of said housing; d. at least one balancing electrode corresponding to each said measuring electrode and being of substantially the same size as its corresponding measuring electrode; and, e. means for supporting each said balancing electrode within and for insulating it from said housing; said means for supporting each said balancing electrode being of substantially the same size as said means for supporting its corresponding measuring electrode.
Claim 3
Dependent Claim
53 words
The probe of claim 1 characterized by said means for supporting said measuring electrode and said means for supporting said balancing electrode being substantially impenetrable by matter from the probe''s environment so as to be adapted to maintain their dielectric constant substantially without change against the influences of the environment of said gauge.
Claim 4
Dependent Claim
29 words
The probe of claim 1 characterized by having the values of capacitance between said housing and said measuring and balancing electrodes substantially unaffected by the environment of said probe.
Claim 5
Dependent Claim
23 words
The probe of claim 1 characterized by having the values of capacitance between said housing and said measuring and balancing electrodes substantially equal.
Claim 6
Dependent Claim
21 words
The probe of claim 1 wherein said measuring and balancing electrodes and their supporting means have equal coefficients of temperature expansion.
Claim 7
Dependent Claim
28 words
The probe of claim 1 further characterized by having means for sealing the opening of said housing against the penetration of matter from the environment of said probe.
Claim 8
Dependent Claim
42 words
The probe of claim 1 wherein said measuring and balancing electrodes are spaced along the axis of said housing and away from said housing, said electrodes being characterized as being axially thin relative to the distance between said electrodes and said housing.
Claim 9
Dependent Claim
50 words
The probe of claim 1 having a substantially plane surface across the opening of said housing, said plane surface comprising an exposed face of each said measuring electrode and an exposed face of said means for supporting each said measuring electrode and the termination of said housing at said opening.
Claim 10
Dependent Claim
47 words
The probe of claim 1 having a contoured surface across the opening of said housing, said contoured surface comprising an exposed face of each said measuring electrode, an exposed face of said means for supporting said measuring electrode, and the termination of said housing at said opening.
Claim 11
Dependent Claim
196 words
A capacitive probe for use in a dimension measuring gauge comprising: a. an electrically conductive cylindrical housing having an opening; b. a first assembly comprising: i. at least one measuring electrode; ii. a dielectric first annulus for supporting said measuring electrode within and insulating it from said housing near said opening; and, iii. an electrically conducting first ring, said measuring electrode having a cylindrical shape with a periphery substantially parallel to an inner wall of said housing, said dielectric fiRst annulus surrounding the periphery of said measuring electrode and in electrical contact therewith, the periphery of said first annulus being substantially parallel to the inner wall of said housing, said first ring surrounding the periphery of said first annulus and making electrical contact therewith and with said housing; and, c. a second assembly comprising: i. at least one balancing electrode corresponding to each said measuring electrode and of similar dimensions to its corresponding measuring electrode; ii. a dielectric second annulus for supporting said balancing electrode within and for insulating it from said housing, and iii. an electrically conducting second ring, said second assembly being substantially the same in size, shape, and construction as said first assembly.
Claim 12
Dependent Claim
196 words
A capacitive probe for use in a dimension measuring gauge comprising: a. an electrically conductive cylindrical housing having an opening; b. a first assembly comprising: i. at least one measuring electrode; ii. a dielectric first annulus for supporting said measuring electrode within and insulating it from said housing near said opening; and, iii. an electrically conducting first ring, said measuring electrode having a cylindrical shape with a periphery substantially parallel to an inner wall of said housing, said dielectric fiRst annulus surrounding the periphery of said measuring electrode and in electrical contact therewith, the periphery of said first annulus being substantially parallel to the inner wall of said housing, said first ring surrounding the periphery of said first annulus and making electrical contact therewith and with said housing; and, c. a second assembly comprising: i. at least one balancing electrode corresponding to each said measuring electrode and of similar dimensions to its corresponding measuring electrode; ii. a dielectric second annulus for supporting said balancing electrode within and for insulating it from said housing, and iii. an electrically conducting second ring, said second assembly being substantially the same in size, shape, and construction as said first assembly.
Claim 13
Dependent Claim
122 words
The probe of claim 10 wherein each said measuring electrode, said first ring, and said first annulus are substantially identical to each said corresponding balancing electrode, said second ring, and said second annulus respectively with the machining tolerances therefore substantially better than one one-thousandth of an inch on at least the following dimensions: a. the peripheral shape and height of said electrodes; b. the inner surface shape and height of said annular rings; and c. the overall spacing between the inner surface of said annular rings and the outer peripheries of said electrodes through said annuli wherein there is established equality of the capacitance between said measuring electrode and said housing relative to the capacitance between said balancing electrode and said housing.
Claim 14
Dependent Claim
32 words
The probe of claim 11 further characterized by said first and second annuli being adapted to maintain their dielectric constant substantially without change against the influences of the environment of said probe.
Claim 15
Dependent Claim
25 words
The probe of claim 11 characterized by having said first and second annuli impenetrable to and non-absorptive of matter from the environmental of said probe.
Claim 16
Dependent Claim
28 words
The probe of claim 11 further characterized by having means for sealing the opening of said housing against the penetration of matter from the environment of said probe.
Claim 17
Dependent Claim
29 words
The probe of claim 14 wherein said means for sealing comprises a covering over said housing at its open end and over an exposed surface of said first assembly.
Claim 18
Dependent Claim
32 words
The probe of claim 10 further characterized by said first and second annuli being adapted to maintain their dielectric constant substantially without change against the influences of the environment of said probe.
Claim 19
Dependent Claim
19 words
The probe of claim 10 further characterized by said rings, annuli and electrodes having matched coefficients of temperature expansion.
Claim 20
Dependent Claim
25 words
The probe of claim 10 characterized by having said first and second annuli impenetrable to and non-absorptive of matter from the environment of said probe.
Claim 21
Dependent Claim
28 words
The probe of claim 10 further characterized by having means for sealing the opening of said housing against the penetration of matter from the environment of said probe.
Claim 22
Dependent Claim
37 words
The probe of claim 10 further characterized by having a retaining ring into which said first and second assemblies fit from opposing openings and are retained, said housing adapted for receiving and resiliently retaining said retaining ring.
Claim 23
Dependent Claim
32 words
The probe of claim 20 further characterized by said first and second annuli being adapted to maintain their dielectric constant substantially without change against the influences of the environment of said probe.
Claim 24
Dependent Claim
25 words
The probe of claim 20 characterized by having said first and second annuli impenetrable to and non-absorptive of matter from the environment of said probe.
Claim 25
Dependent Claim
19 words
The probe of claim 20 further characterized by said rings, annuli and electrodes having matched coefficients of temperature expansion.
Claim 26
Dependent Claim
28 words
The probe of claim 20 further characterized by having means for sealing the opening of said housing against the penetration of matter from the environment of said probe.
Claim 27
Dependent Claim
19 words
The pRobe of claim 11 further characterized by said rings, annuli and electrodes having matched coefficients of temperature expansion.
Claim 28
Dependent Claim
126 words
A capacitive probe for use in a dimension measuring gauge comprising: a. an electrically conductive housing having an opening; b. at least one measuring electrode; c. means for supporting each said measuring electrode within and insulating it from said housing near the opening of said housing; d. at least one balancing electrode corresponding to each said measuring electrode and of similar dimensions to its corresponding measuring electrode; and, e. means for supporting each said balancing electrode within and for insulating it from said housing, said means for supporting each said balancing electrode being dimensioned similar to said means for supporting its corresponding measuring electrode, said means for supporting said measuring electrode and said means for supporting said balancing electrode comprising a dielectric oxide of a metal.
Claim 29
Dependent Claim
126 words
A capacitive probe for use in a dimension measuring gauge comprising: a. an electrically conductive housing having an opening; b. at least one measuring electrode; c. means for supporting each said measuring electrode within and insulating it from said housing near the opening of said housing; d. at least one balancing electrode corresponding to each said measuring electrode and of similar dimensions to its corresponding measuring electrode; and, e. means for supporting each said balancing electrode within and for insulating it from said housing, said means for supporting each said balancing electrode being dimensioned similar to said means for supporting its corresponding measuring electrode, said means for supporting said measuring electrode and said means for supporting said balancing electrode comprising a dielectric oxide of a metal.
Claim 30
Dependent Claim
25 words
The probe of claim 26 wherein said supporting means comprise the oxide of a metal from the group consisting of aluminum, beryllium, silicon, and titanium.
Claim 31
Dependent Claim
115 words
A capacitive probe for use in a dimension measuring gauge comprising: a. an electrically conductive housing having an opening; b. at least one measuring electrode; c. means for supporting each said measuring electrode within and insulating it from said housing near the opening of said housing; d. at least one balancing electrode corresponding to each said measuring electrode; e. means for supporting each said balancing electrode within and for insulating it from said housing, said means for supporting each said balancing electrode being dimensioned similar to said means for supporting its corresponding measuring electrode; and, f. filler means placed between each said electrode and each supporting means, said filler means being a ductile conducting substance.
Claim 32
Dependent Claim
115 words
A capacitive probe for use in a dimension measuring gauge comprising: a. an electrically conductive housing having an opening; b. at least one measuring electrode; c. means for supporting each said measuring electrode within and insulating it from said housing near the opening of said housing; d. at least one balancing electrode corresponding to each said measuring electrode; e. means for supporting each said balancing electrode within and for insulating it from said housing, said means for supporting each said balancing electrode being dimensioned similar to said means for supporting its corresponding measuring electrode; and, f. filler means placed between each said electrode and each supporting means, said filler means being a ductile conducting substance.
Claim 33
Dependent Claim
144 words
A capacitive probe for use in a dimension measuring gauge comprising: a. an electrically conductive housing having an opening; b. at least one measuring electrode; c. means for supporting each said measuring electrode within and insulating it from said housing near the opening of said housing; d. at least one balancing electrode corresponding to each said measuring electrode and of similar dimensions to its corresponding measuring electrode; e. means for supporting each said balancing electrode within and for insulating it from said housing, said means for supporting each said balancing electrode being dimensioned similar to said means for supporting its corresponding measuring electrode; and, f. means for sealing the opening of said housing against foreign matter, said sealing means comprising a cover over the opening of said housing and comprising an oxide of metal from the group consisting of aluminum, beryllium, silicon and titanium.
Claim 34
Dependent Claim
144 words
A capacitive probe for use in a dimension measuring gauge comprising: a. an electrically conductive housing having an opening; b. at least one measuring electrode; c. means for supporting each said measuring electrode within and insulating it from said housing near the opening of said housing; d. at least one balancing electrode corresponding to each said measuring electrode and of similar dimensions to its corresponding measuring electrode; e. means for supporting each said balancing electrode within and for insulating it from said housing, said means for supporting each said balancing electrode being dimensioned similar to said means for supporting its corresponding measuring electrode; and, f. means for sealing the opening of said housing against foreign matter, said sealing means comprising a cover over the opening of said housing and comprising an oxide of metal from the group consisting of aluminum, beryllium, silicon and titanium.
Claim 35
Dependent Claim
131 words
A capacitive probe for use in a dimension measuring gauge comprising: a. an electrically conductive housing having an opening; b. at least one measuring electrode; c. means for supporting each said measuring electrode within and insulating it from said housing near the opening of said housing; d. at least one balancing electrode corresponding to each said measuring electrode and of similar dimensions to its corresponding measuring electrode; e. means for supporting each said balancing electrode within and for insulating it from said housing, said means for supporting each said balancing electrode being dimensioned similar to said means for supporting its corresponding electrode; and; f. means for sealing the opening of said housing against foreign matter, said sealing means comprising a covering over the opening of said housing and comprising a silicon.
Claim 36
Dependent Claim
131 words
A capacitive probe for use in a dimension measuring gauge comprising: a. an electrically conductive housing having an opening; b. at least one measuring electrode; c. means for supporting each said measuring electrode within and insulating it from said housing near the opening of said housing; d. at least one balancing electrode corresponding to each said measuring electrode and of similar dimensions to its corresponding measuring electrode; e. means for supporting each said balancing electrode within and for insulating it from said housing, said means for supporting each said balancing electrode being dimensioned similar to said means for supporting its corresponding electrode; and; f. means for sealing the opening of said housing against foreign matter, said sealing means comprising a covering over the opening of said housing and comprising a silicon.
Claim 37
Dependent Claim
138 words
A capacitive probe for use in a dimension measuring gauge comprising: a. an electrically conductive housing having an opening; b. at least one measuring electrode; c. means fOr supporting each said measuring electrode within and insulating it from said housing near the opening of said housing; d. at least one balancing electrode corresponding to each said measuring electrode and of similar dimensions to its corresponding measuring electrode; e. means for supporting each said balancing electrode within and for insulating it from said housing, said means for supporting each said balancing electrode being dimensioned similar to said means for supporting its corresponding measuring electrode; and, f. a retaining ring into which said means for supporting said measuring and balancing electrodes fit and are retained within said housing, said housing being adapted to receive and resiliently retain said retaining ring.
Claim 38
Dependent Claim
138 words
A capacitive probe for use in a dimension measuring gauge comprising: a. an electrically conductive housing having an opening; b. at least one measuring electrode; c. means fOr supporting each said measuring electrode within and insulating it from said housing near the opening of said housing; d. at least one balancing electrode corresponding to each said measuring electrode and of similar dimensions to its corresponding measuring electrode; e. means for supporting each said balancing electrode within and for insulating it from said housing, said means for supporting each said balancing electrode being dimensioned similar to said means for supporting its corresponding measuring electrode; and, f. a retaining ring into which said means for supporting said measuring and balancing electrodes fit and are retained within said housing, said housing being adapted to receive and resiliently retain said retaining ring.
Claim 39
Dependent Claim
173 words
A capacitive probe for use in a dimension measuring gauge comprising: a. an electrically conductive housing having an opening; b. at least one measuring electrode; c. means for supporting each said measuring electrode within and insulating it from said housing near the opening of said housing, said supporting means being a dielectric first substrate with a measuring electrode comprising a first central deposition thereon; d. at least one balancing electrode corresponding to each said measuring electrode and of similar dimensions to its corresponding measuring electrode; and e. means for supporting each said balancing electrode within and for insulating it from said housing, said means for supporting each said balancing electrode being dimensioned similar to said means for supporting its corresponding measuring electrode, said balancing electrode supporting means being a dielectric second substrate with a balancing electrode comprising a second central deposition thereon, said housing being adapted to receive and retain said first and second substrates in substantially parallel relationship and with said central depositions being aligned along a central axis through said housing.
Claim 40
Dependent Claim
173 words
A capacitive probe for use in a dimension measuring gauge comprising: a. an electrically conductive housing having an opening; b. at least one measuring electrode; c. means for supporting each said measuring electrode within and insulating it from said housing near the opening of said housing, said supporting means being a dielectric first substrate with a measuring electrode comprising a first central deposition thereon; d. at least one balancing electrode corresponding to each said measuring electrode and of similar dimensions to its corresponding measuring electrode; and e. means for supporting each said balancing electrode within and for insulating it from said housing, said means for supporting each said balancing electrode being dimensioned similar to said means for supporting its corresponding measuring electrode, said balancing electrode supporting means being a dielectric second substrate with a balancing electrode comprising a second central deposition thereon, said housing being adapted to receive and retain said first and second substrates in substantially parallel relationship and with said central depositions being aligned along a central axis through said housing.
Claim 41
Dependent Claim
71 words
The capacitive probe of claim 32 further comprising: a. an electrically conducting first deposition band located on said first substrate and surrounding said first central deposition; and, b. an electrically conducting second deposition band located on said second substrate and surrounding said second central deposition, said first and second deposition bands being adapted to make electrical contact with said housing along an outer periphery of said first and second substrates respectively.
Claim 42
Dependent Claim
27 words
The capacitive probe of claim 33 further characterized by said first and second substrates being non-absorptive of and impenetrable to matter from the environment of said probe.
Claim 43
Dependent Claim
28 words
The probe of claim 33 further characterized by having means for sealing the interior of said housing against penetration thereinto of matter from the environment of said probe.
Claim 44
Dependent Claim
25 words
The probe of claim 35 wherein said means for sealing is a non-conducting covering across the opening of said housing and over said first substrate.
Claim 45
Dependent Claim
123 words
The probe of claim 33 further characterized: a. by said first and second central depositions being of substantially similar configuration, size and orientation to each other and substantially similar configuration and orientation to the cross-sectional shape of an interior wall of said housing in a plane perpendicular to the central axis of said housing; and, b. by having the configuration, orientation, and size of said first and second deposition bands substantially equal to each other with an inner edge of said first and second deposition bands of substantially similar configuration and orientation to an outer edge of said first and second central depositions respectively to maintain a constant separation between the inner edges of said bands and outer edges of said central depositions.
Claim 46
Dependent Claim
22 words
The probe of claim 33 wherein said first and second substrates are characterized by having low and equal temperature coefficients of expansion.
Claim 47
Dependent Claim
29 words
The probe of claim 33 wherein said deposition banDs and said central depositions are further characterized by being as thin as is consistant with their being good electrical conductors.
Claim 48
Dependent Claim
22 words
The probe of claim 32 wherein said first and second substrates are characterized by having low and equal temperature coefficients of expansion.
Claim 49
Dependent Claim
22 words
The probe of claim 32 wherein said central depositions are further characterized by being thin in the direction of said housing''s axis.
Claim 50
Dependent Claim
29 words
The probe of claim 32 wherein said second substrate is characterized by having a central hole passing through said second central deposition in the direction of said housing''s axis.
Claim 51
Dependent Claim
46 words
The probe of claim 42 wherein said second central deposition is further characterized by passing through said hole in said second substrate from one side thereof to the other and forming a continuous deposition to electrically connect the sides of said second substrate through said hole.
Claim 52
Dependent Claim
61 words
The capacitive probe of claim 1 characterized by having means for guarding said measuring and balancing electrodes by surrounding said measuring and balancing electrodes with an electrical conductor at approximately the same instantaneous potential as is applied to said electrodes, whereby flux switching in the flux of each said measuring electrode from a surface being gauged to said housing is minimized.
Claim 53
Dependent Claim
28 words
The probe of claim 44 wherein said means for guarding said measuring and balancing electrodes comprises an inner conductor insulatingly supported within an inner wall of said housing.
Claim 54
Dependent Claim
24 words
The probe of claim 44 characterized by having said means for supporting impenetrable to and non-absorptive of matter from the environment of said probe.
Claim 55
Dependent Claim
28 words
The probe of claim 44 further characterized by having means for sealing the opening of said housing against the penetration of matter from the environment of said probe.
Claim 56
Dependent Claim
150 words
A compensating capacitive probe for use in measuring the capacitance between said probe and a surface over a plurality of separate areas between said probe and said surface, said probe comprising: a. a housing of electrically conductive material enclosing a volume and having at least one open end, b. first and second tip assemblies, each assembly comprising: i. a dielectric sheet; ii. a plurality of electrically conducting probe tips associated with said sheet; and, c. means for securing each said tip assembly within said housing with said first tip assembly placed at an open end of said housing to define an exposed surface comprising an end section of said housing, an exposed surface of said dielectric sheet, and an exposed surface of each said tip associated with said first tip assembly, and, with said second tip assembly secured substantially parallel to said first tip assembly and further within said housing.
Claim 57
Dependent Claim
150 words
A compensating capacitive probe for use in measuring the capacitance between said probe and a surface over a plurality of separate areas between said probe and said surface, said probe comprising: a. a housing of electrically conductive material enclosing a volume and having at least one open end, b. first and second tip assemblies, each assembly comprising: i. a dielectric sheet; ii. a plurality of electrically conducting probe tips associated with said sheet; and, c. means for securing each said tip assembly within said housing with said first tip assembly placed at an open end of said housing to define an exposed surface comprising an end section of said housing, an exposed surface of said dielectric sheet, and an exposed surface of each said tip associated with said first tip assembly, and, with said second tip assembly secured substantially parallel to said first tip assembly and further within said housing.
Claim 58
Dependent Claim
17 words
The compensating capacitive probe of claim 48 wherein said first and second tip assemblies are substantially identical.
Claim 59
Dependent Claim
74 words
The compensating capacitive probe of claim 48 wherein: a. said housing further comprises an interior cylindrical wall, rectangular in cross section with a rectangular cross-sectional opening where said first tip assembly is secured; and, b. a plurality of conducting rectangular tips are provided in line across the long dimension of the rectangular cross-section of said housing with each peripheral edge of each said tip substantially parallel to an edge of said interior cylindrical wall.
Claim 60
Dependent Claim
43 words
The compensating capacitive probe of claim 48 further including means for guarding said electrically conducting tips between said housing and said tips whereby electric flux from said electrically conducting tips in said first tip assembly is confined toward the direction of said surface.
Claim 61
Dependent Claim
28 words
The compensating capacitive probe of claim 48 wherein said tips fit into perforations in said dielectric sheets and are flush with the opposing faces of said dielectric sheets.
Claim 62
Dependent Claim
126 words
The compensating capacitive probe of claim 52 wherein at least the following dimeNsions occurring in both first and second tip assemblies are maintained substantially identical for corresponding portions of said first and second tip assemblies to tolerances of substantially better than one one-thousandths of an inch: a. the distances between peripheral edges of said tips and the interior cylindrical wall of said housing; b. the thickness of each said tip at its periphery in a direction from one face to the opposing face of each said dielectric sheet; c. the dimensions of each said tip lying parallel to its face; and d. the degree to which faces of each said tip are parallel with the faces of said dielectric sheets and are parallel to said surface.
Claim 63
Dependent Claim
34 words
The compensating capacitive probe of claim 53 wherein the thickness of each said electrically conducting tip is of low significance in determining the capacitance between each said tip and said housing or said surface.
Claim 64
Dependent Claim
35 words
The compensating capacitive probe of claim 48 wherein: a. each said dielectric sheet is a dielectric substrate; and, b. each said electrically conducting tip is a deposition of an electrically conducting substance on said substrate.
Claim 65
Dependent Claim
40 words
The compensating capacitive probe of claim 55 further comprising a covering over said first tip assembly and housing, said covering inhibiting the passage of matter from the environment of said compensating capacitive probe into the volume enclosed by said housing.
Claim 66
Dependent Claim
30 words
The compensating capacitive probe of claim 55 wherein each said dielectric substrate is further characterized by being non-absorptive and impenetrable to matter from the environment of said compensating capacitive probe.
Claim 67
Dependent Claim
45 words
The compensating capacitive probe of claim 48 further comprising a covering over said first tip assembly and extending to said housing, said covering adapted to inhibit the penetration of matter from the environment of said compensating capacitive probe into the volume bounded by said housing.
Claim 68
Dependent Claim
30 words
The compensating capacitive probe of claim 48 wherein each said dielectric sheet is further characterized by being non-absorptive and impenetrable to matter from the environment of said compensating capacitive probe.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-12-19 | 1976-06-19 | 1976-12-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-12-19 | 1980-06-19 | 1980-12-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-12-19 | 1984-06-19 | 1984-12-19 | $7700.00 | Window Closed / Lapsed |