Capacitive Pressure Sensor

• US 20070209443A1
• Filed: 05/12/2005
• Published: 09/13/2007
• Est. Priority Date: 05/19/2004
• Status: Active Grant

• Current Assignee: Yamatake Corporation
• Original Assignee: Yamatake Corporation
• Inventors: Yamaguchi, Toru, Ishikura, Yoshiyuki, Yoshikawa, Yasuhide
• Granted Patent: US 7,401,524 B2
• Time in Patent Office: Days
• 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 a signal output value of the reference capacitance detecting portion is independently detected.

2. The capacitance type pressure sensor according to claim 1, wherein 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 a predetermined external output value is output when the signal output value of the reference capacitance detecting portion exceeds the fixed range.

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 1, wherein the signal output value of the reference capacitance detecting portion is output as an external output value.

5. The capacitance type pressure sensor according to claim 2, wherein an external output value corresponding to a pressure is obtained 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 the external output value in place of outputting the predetermined external output signal according to claim 2 when the signal output value of the reference capacitance detecting portion exceeds the fixed range.