Electrostatic capacitance type pressure detector

• US 5,042,308 A
• Filed: 06/22/1989
• Issued: 08/27/1991
• Est. Priority Date: 06/23/1988
• Status: Expired due to Fees

• Current Assignee: Fuji Electric Company Limited (Fuji Electric Systems Company Limited)
• Original Assignee: Fuji Electric Company Limited (Fuji Electric Systems Company Limited)
• Inventors: Takahama, Teizo, Takano, Toshiyuki, Matsuda, Mikihiko, Nakamura, Kimihiro, Tamai, Mitsuru
• Primary Examiner(s): Woodiel, Donald O.
• Application Number:
  US07/369,847
• Time in Patent Office: 796 Days
• Field of Search: 73/718, 73/724, 73/708, 361/283
• US Class Current: 73/718
• CPC Class Codes: G01L 9/0073 using a semiconductive diaphragm
• CPC Class Codes: G01L 9/125 with temperature compensating means non electric temperature compensating means G01L19/04

Abstract

A pressure detector for measuring the pressure of a pressurized fluid by means of electrostatic capacitance comprising a diaphragm displaceable in response to the pressure, and a pair of fixed electrodes, one of each of the fixed electrodes being located on each side of the diaphragm and being electrostatically capacitively coupled to the diaphragm, each of the fixed electrodes being shaped to essentially eliminate electrostatic capacitances that are not differentially linear with respect to the pressure.

Claims

1. A pressure detector for measuring the pressure of a pressurized fluid by means of electrostatic capacitances comprising:

a diaphragm displaceable in response to the pressure; and

a pair of fixed electrodes, one of each of said fixed electrodes being located on each side of said diaphragm and being electrostatically capacitively coupled to said diaphragm, each of said fixed electrodes being shaped to essentially eliminate electrostatic capacitances that are not differentially linear with respect to the pressure.

2. A pressure detector according to claim 1, wherein each of the fixed electrodes includes a first portion close to and opposite a surface of the diaphragm and a second portion supported by an insulating material to provide a gap between said second portion and the surface of the diaphragm.

3. A pressure detector according to claim 2, wherein each of said fixed electrodes contains a hole for receiving the pressurized fluid.

4. An electrostatic capacitance type pressure detector for measuring the pressure of a pressurized fluid by means of the electrostatic capacitance formed between a diaphragm having a center portion and being displaceable in response to the pressure and a pair of fixed electrodes separately disposed on opposite sides of the diaphragm, wherein each of the fixed electrodes comprises:

an electrode body having at a center portion of a side thereof a projection extending toward and close to the surface of the center portion of the diaphragm, and having a hole for receiving the fluid under pressure; and

a support joined to a peripheral edge portion of said electrode body of the side of the body to enclose said projection, said support also being joined to a peripheral edge portion of the diaphragm at an end surface opposite to the joined portion of said electrode body, said support being made of an insulating material.

5. An electrostatic capacitance type pressure detector for measuring the pressure of a pressurized fluid by means of the electrostatic capacitance formed between a diaphragm having a center portion and being displaceable in response to the pressure and a pair of fixed electrodes separately disposed on opposite sides of the diaphragm, wherein each of the fixed electrodes comprises:

a center electrode body having an end surface close to and opposite the surface of the center portion of the diaphragm, and having a hole for receiving the pressurized fluid;

an annular insulator joined to an outer peripheral surface of said center electrode body; and

an annular electrical conductor joined to an outer peripheral surface of said annular insulator, and insulatively joined at an end surface to a peripheral edge portion of the diaphragm, the diaphragm being electrically connected to said annular electrical conductor at each of said fixed electrodes.

6. A pressure detector for measuring the pressure of a pressurized fluid by means of electrostatic capacitance comprising:

a diaphragm displaceable in response to the pressure; and

a pair of fixed electrodes separately disposed on each side of said diaphragm and being electrostatically capacitively coupled to said diaphragm said pair of electrodes being shaped to provide corrective capacitance for eliminating capacitances that are not differentially linear with respect to the pressure.

7. A pressure detector for measuring the pressure of a pressurized fluid by means of electrostatic capacitance comprising:

a diaphragm displaceable in response to the pressure;

a pair of fixed electrodes separately disposed on each side of said diaphragm and being electrostatically capacitively coupled to said diaphragm, each of said fixed electrodes being insulatively joined to said diaphragm at a peripheral edge joint; and

corrective capacitance means for eliminating electrostatic capacitances that are not differentially linear with respect to the pressure, said corrective capacitance means having a temperature characteristic that is the same as that at said peripheral edge joint between said diaphragm and each of said fixed electrodes.

8. An electrostatic capacitance type pressure detector comprising:

a center electrode;

first and second diaphragms insulatively joined at junctions to said center elecrode at opposite sides thereof; and

first and second fixed electrodes electrically joined to said first and second diaphragms at opposite sides to said junctions to form gaps between said first and second fixed electrodes and said first and second diaphragms, for measuring the differential pressure between one pressure existing in the gaps on one side of said second diaphragm and another pressure existing in the gap between said first fixed electrode and said first diaphragm on the basis of an electrostatic capacitance formed between said center electrode and each of said first and second fixed electrodes, in which said center electrode comprises an electrode substrate, insultating plates joined to said electrode substrate at opposite sides of said electrode substrate, and conductor plates joined to center portions of outer sides of said insulating plates and electrically connected to said electrode substrate.