Patent US4424713A successfully refreshed from Google Patents.
US4424713A
Expired / Lapsed
US
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Silicon diaphragm capacitive pressure transducer
Assignee: Stock Equipment Co Inc
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Filing: 1982-06-11
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Granted: 1984-01-10
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Expires: 2002-06-11
Abstract
Abstract A capacitive pressure transducer utilizing a plate of electrically conductive semi-conductor material sandwiched between a pair of plates of inorganic electrically insulating material and electrostatically bonded thereto. A pair of concentric circular recesses are etched in the plates in such a way as to form cavities on opposing sides of the conductive plate and to define a diaphragm area on that plate. Apertures are drilled through the insulating plates to expose the cavities to the pressures to be measured. The surfaces of the insulating plates in the cavities have deposited on them electrically conductive surfaces which form capacitors with the diaphragm area on the conductive plate. A stress relief area is provided on the high pressure side surrounding the diaphragm area. In that stress relief area, the conductive plate is unrestrained by the adjacent insulating plate. Provision of this stress relief makes it possible to extend the pressure range of the transducer beyond the range which would normally be useful for the dimensions of the particular transducer.
Inventors
- 👤 Paul M. Kroninger, Jr.
- 👤 Paul J. Freud
- 👤 Dean P. Updike
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 13:24
CPC Classifications
G; G01; G01L; G01L9/00; G01L9/0041; G01L9/0072; G01L9/0073
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
138 words
In a pressure transducer of the capacitor type in which a plate of electrically conductive semi-conductor material is sandwiched between a pair of plates of inorganic electrical insulating material electrostatically bonded thereto, wherein a pair of concentric circular recesses are etched in said plates to form cavities on opposing sides of said conductive plate to define a diaphragm area on said conductive plate, apertures are drilled through said insulating plates, and the surfaces of one of said insulating plates in said cavities has deposited thereon an electrically conductive film forming a capacitor with the diaphragm area of said conductive plate, the improvement comprising: a stress relief area surrounding said diaphragm area so that deflection of said conductive plate is unrestrained by the adjacent insulating plate on the high pressure side for prevention of overpressure failure of said transducer.
Claim 2
Dependent Claim
138 words
In a pressure transducer of the capacitor type in which a plate of electrically conductive semi-conductor material is sandwiched between a pair of plates of inorganic electrical insulating material electrostatically bonded thereto, wherein a pair of concentric circular recesses are etched in said plates to form cavities on opposing sides of said conductive plate to define a diaphragm area on said conductive plate, apertures are drilled through said insulating plates, and the surfaces of one of said insulating plates in said cavities has deposited thereon an electrically conductive film forming a capacitor with the diaphragm area of said conductive plate, the improvement comprising: a stress relief area surrounding said diaphragm area so that deflection of said conductive plate is unrestrained by the adjacent insulating plate on the high pressure side for prevention of overpressure failure of said transducer.
Claim 3
Dependent Claim
54 words
Apparatus as set forth in claim 1 in which the cavities are formed by circular recesses etched into opposite faces of the conductive plate and said stress relief is provided by having the diameter of the recess on the high pressure side greater than the diameter of the recess on the low pressure side.
Claim 4
Dependent Claim
57 words
Apparatus as set forth in claim 1 in which the cavity on the high pressure side is formed by a recess in the insulating plate on that side and the stress relief is provided by providing said recess on the high pressure side with a diameter greater than that of the recess on the low pressure side.
Claim 5
Dependent Claim
30 words
Apparatus as set forth in claim 1, 2, or 3 in which said conductive plate is made of single crystal silicon and said insulating plates are made of borosilicate glass.
Claim 6
Dependent Claim
33 words
Apparatus as set forth in claims 2 or 3 in which the recess on the high pressure side is at least 1.3 times the diameter of the recess on the low pressure side.
Claim 7
Dependent Claim
47 words
Apparatus as set forth in claim 1 in which the stress relief is provided by providing an unbonded region in the interface between the insulating plate on the high pressure side and the conductive plate, said region being peripheral to the cavity on the high pressure side.
Claim 8
Dependent Claim
32 words
Apparatus as set forth in claim 6 in which the unbonded region extends to a diameter which is more than 1.3 times the diameter of the cavity on the low pressure side.
Claim 9
Dependent Claim
100 words
In a pressure transducer of the type having a first plate sandwiched between a pair of plates bonded thereto, wherein said plates have a pair of concentric circular recesses forming cavities on opposing sides of said first plate to define a diaphragm area on said first plate, and wherein said cavities are exposed to the pressures to be compared, the improvement comprising: a stress relief area surrounding said diaphragm area on the high pressure side of said first plate so that deflection of said first plate is unrestrained by the adjacent plate for prevention of overpressure failure of said transducer.
Claim 10
Dependent Claim
100 words
In a pressure transducer of the type having a first plate sandwiched between a pair of plates bonded thereto, wherein said plates have a pair of concentric circular recesses forming cavities on opposing sides of said first plate to define a diaphragm area on said first plate, and wherein said cavities are exposed to the pressures to be compared, the improvement comprising: a stress relief area surrounding said diaphragm area on the high pressure side of said first plate so that deflection of said first plate is unrestrained by the adjacent plate for prevention of overpressure failure of said transducer.
Claim 11
Dependent Claim
54 words
Apparatus as set forth in claim 8 in which the cavities are formed by circular recesses etched into opposite faces of said first plate and said stress relief is provided by having the diameter of the recess on the high pressure side greater than the diameter of the recess on the low pressure side.
Claim 12
Dependent Claim
63 words
Apparatus as set forth in claim 8 in which the cavity on the high pressure side is formed by a recess in that one of said pair of plates on the high pressure side and the stress relief is provided by providing said recess on the high pressure side with a diameter greater than that of the recess on the low pressure side.
Claim 13
Dependent Claim
31 words
Apparatus as set forth in claim 8, 9, or 10 in which said first plate is made of single crystal silicon and said pair of plates are made of borosilicate glass.
Claim 14
Dependent Claim
33 words
Apparatus as set forth in claim 9 or 10 in which the recess on the high pressure side is at least 1.3 times the diameter of the recess on the low pressure side.
Claim 15
Dependent Claim
51 words
Apparatus as set forth in claim 8 in which the stress relief is provided by providing an unbonded region in the interface between that one of said pair of plates on the high pressure side and said first plate, said region being peripheral to the cavity on the high pressure side.
Claim 16
Dependent Claim
32 words
Apparatus as set forth in claim 13 in which the unbonded region extends to a diameter which is more than 1.3 times the diameter of the cavity on the low pressure side.
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) | 1987-01-09 | 1987-07-11 | 1988-01-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-01-09 | 1991-07-11 | 1992-01-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-01-09 | 1995-07-11 | 1996-01-10 | $7700.00 | Window Closed / Lapsed |