Capacitive pressure sensor

• US 7,401,524 B2
• Filed: 05/12/2005
• Issued: 07/22/2008
• Est. Priority Date: 05/19/2004
• Status: Active Grant

• Current Assignee: Yamatake Corporation
• Original Assignee: Yamatake Corporation
• Inventors: Ishikura, Yoshiyuki, Yamaguchi, Toru, Yoshikawa, Yasuhide
• Primary Examiner(s): THOMPSON, JEWEL VERGIE
• Application Number:
  US11/597,110
• Publication Number:
  US 20070209443A1
• Time in Patent Office: 1,167 Days
• Field of Search: 737/18, 737/24
• US Class Current: 73/718
• CPC Class Codes: G01L 9/0075 using a ceramic diaphragm, e.g. alumina, fused quartz, glass
• CPC Class Codes: G01L 9/125 with temperature compensating means non electric temperature compensating means G01L19/04

Abstract

In a capacitance type pressure sensor (1) including capacitance detecting portions formed in opposed regions in a capacitance chamber which is at least partially formed of a diaphragm, the capacitance detecting portions being a pressure-sensitive capacitance detecting portion (101) formed in a region of the diaphragm having large sensitivity with respect to a pressure and a reference capacitance detecting portion (102) formed in a region of the diaphragm having small sensitivity with respect to a pressure, there is provided the capacitance type pressure sensor which is entirely small in size and superior in reliability by independently detecting a signal output value of the reference capacitance detecting portion (102).

Claims

1. A capacitance type pressure sensor comprising capacitance detecting portions formed in opposed regions in a capacitance chamber which is at least partially formed of a diaphragm, the capacitance detecting portions being a pressure-sensitive capacitance detecting portion which is formed in region of the diaphragm having large sensitivity with respect to a pressure and a reference capacitance detecting portion which is formed in a region of the diaphragm having small sensitivity with respect to a pressure,

wherein the pressure sensor is structured such that a signal output value of the reference capacitance detecting portion is detected independently of a signal for correction calculation and outputted as a pressure signal even in a region exceeding a measurement range of the regular pressure-sensitive capacitance detecting portion.

2. The capacitance type pressure sensor according to claim 1, wherein the pressure sensor is structured such that an external output value corresponding to a pressure is output based on a signal output value of the pressure-sensitive capacitance detecting portion and a signal output value of the reference capacitance detecting portion when the signal output value of the reference capacitance detecting portion falls within a fixed range, and the signal output value of the pressure-sensitive capacitance detecting portion is fixed to a predetermined signal output value in a region where the signal output value of the reference capacitance detecting portion exceeds a measurement range of the regular pressure-sensitive capacitance detecting portion.

3. The capacitance type pressure sensor according to claim 2, wherein an alarm is given when the signal output value of the reference capacitance detecting portion exceeds the fixed range.

4. The capacitance type pressure sensor according to claim 2, wherein the pressure sensor is structured such that an external output value corresponding to a pressure is output as a pressure signal based on a signal output value of the pressure-sensitive capacitance detecting portion and a signal output value of the reference capacitance detecting portion when the signal output value of the reference capacitance detecting portion falls within a fixed range, and the signal output value of the reference capacitance detecting portion is output as a pressure signal upon determination that a measurement range of the regular pressure-sensitive capacitance detecting portion is exceeded when the signal output value of the reference capacitance detecting portion exceeds the fixed range.