Patent EP0059488A1 successfully refreshed from Google Patents.
EP0059488A1
Expired / Lapsed
EP
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Capacitive pressure sensor
Assignee: Hitachi Ltd
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Filing: 1979-07-20
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Granted: —
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Expires: 1999-07-20
Abstract
Abstract A capacitive pressure sensor includes at least one stationary substrate (300a, 300b) and a diaphragm (250) having a portion movable with respect to the substrate, a pressure chamber (205a, 205b) being defined between the diaphragm and the at least one substrate and filled with a fluid exposed to the pressure to be detected. The diaphragm (250) is formed of silicon as an electrically conductive material, thus serving as one electrode of the capacitive sensor. The substrate or substrates are formed of silicon, thus themselves forming the opposite electrode or electrodes of the capacitive sensor. Spacers of insulating material such as borosilicate glass, quartz, soft glass or sapphire, are bonded between the diaphragm and the substrate or substrates by an anodic bonding process.
Inventors
- 👤 Kanji Kawakami
- 👤 Satoshi Shimada
- 👤 Motohisa Nishihara
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-04 22:58
CPC Classifications
G; G01; G01L; G01L13/00; G01L13/02; G01L13/025; G01L9/00; G01L9/0041; G01L9/0042; G01L9/0072; G01L9/0073
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
187 words
'A capacitive pressure sensor including at least one substrate (300a, 503) in which a conduit (320a, 504) is formed, a diaphragm (303, 250, 500) of conductive silicon having a thick supporting portion (207, 251) rigidly and sealingly bonded to the substrate, and a thin deflecting portion (206, 252, 506) surrounded by the thick supporting portion (207, 250) and adapted to be deflected by pressure, a pressure chamber (205a, 505a) formed between the substrate (300a, 503) and the diaphragm, into which chamber a fluid under the pressure to be sensed is admitted through the conduit (320a, 504), and a stationary electrode facing the diaphragm (203, 250, 500) and forming a capacity therewith, characterized in that the substrate (300a, 503) is made of conductive silicon and forms the stationary electrode, that a spacer (310a, 502) of borosilicate glass having a pair of parallel plane surfaces is interposed between the substrate (300a, 503) and the diaphragm supportion portion (207, 251), and that the diaphragm (203, 250) is joined to the spacer (310a, 502) and the spacer (310a, 502) is joined to the substrate (300a, 503) by an anodic bonding process.
Claim 2
Dependent Claim
187 words
'A capacitive pressure sensor including at least one substrate (300a, 503) in which a conduit (320a, 504) is formed, a diaphragm (303, 250, 500) of conductive silicon having a thick supporting portion (207, 251) rigidly and sealingly bonded to the substrate, and a thin deflecting portion (206, 252, 506) surrounded by the thick supporting portion (207, 250) and adapted to be deflected by pressure, a pressure chamber (205a, 505a) formed between the substrate (300a, 503) and the diaphragm, into which chamber a fluid under the pressure to be sensed is admitted through the conduit (320a, 504), and a stationary electrode facing the diaphragm (203, 250, 500) and forming a capacity therewith, characterized in that the substrate (300a, 503) is made of conductive silicon and forms the stationary electrode, that a spacer (310a, 502) of borosilicate glass having a pair of parallel plane surfaces is interposed between the substrate (300a, 503) and the diaphragm supportion portion (207, 251), and that the diaphragm (203, 250) is joined to the spacer (310a, 502) and the spacer (310a, 502) is joined to the substrate (300a, 503) by an anodic bonding process.
Claim 3
Dependent Claim
61 words
The pressure sensor of claim 1, characterized in that the diaphragm (250, 500) has a thick movable portion (253) in the center thereof, and that the thin deflecting portion (252, 501) is formed between the thick supporting portion (251) and the thick movable portion (253) so that the diaphragm (250, 500) is deformed only at the thin deflecting portion (252, 501).
Claim 4
Dependent Claim
35 words
The pressure sensor of claim 2, characterized in that the thin deflecting portion (252) of the diaphragm (250) is reduced symmetrically in thickness from the thick supporting portion (251) to the thick movable portion (253).
Claim 5
Dependent Claim
42 words
The pressure sensor of claim 3, characterized in that a pair of pressure chambers 205a, 205b) is provided at opposite sides of the diaphragm (250), each pressure chamber being.defined by the diaphragm (250) and a substrate (300a, 300b) for forming the capacity.
Claim 6
Dependent Claim
26 words
The pressure sensor of any of claims 1 to 4, characterized in that the diaphragm surface is covered with a layer (401a, 401b) of silicon dioxide.
Claim 7
Dependent Claim
19 words
The pressure sensor of any of claims 1 to 5, characterized in that the thin deflection portion is annular.
References Cited (Backward Citations)
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Cited
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