Acceleration sensor

• US 6,601,431 B2
• Filed: 09/26/2001
• Issued: 08/05/2003
• Est. Priority Date: 04/16/2001
• Status: Expired due to Term

• Current Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Original Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation), Mitsubshi Electric Engineering Company Limited (Mitsubishi Electric Corporation)
• Inventors: Kaido, Yoshikazu, Nagahara, Teruaki
• Primary Examiner(s): CHAPMAN JR, JOHN E
• Application Number:
  US09/962,310
• Publication Number:
  US 20020148291A1
• Time in Patent Office: 678 Days
• Field of Search: 73/13.8, 73/13.9, 735/143.2, 735/141.8, 280/735
• US Class Current: 73/1.38
• CPC Class Codes: G01P 15/125 by capacitive pick-up

Abstract

An acceleration sensor which can improve precision during self-diagnosis operation. The acceleration sensor includes an amplifier circuit which amplifies a detection signal obtained by converting changes in capacitance between a movable electrode and a self-diagnosis electrode into an electric signal to output the amplified signal as a self-diagnosis signal. The amplifier factor of the amplifier circuit during self-diagnosis operation is controlled to be greater than the factor during non-self-diagnosis operation.

Claims

1. An acceleration sensor for detecting acceleration based on changes in capacitance between a movable electrode and fixed electrodes provided on a semiconductor sensor chip, the acceleration sensor comprising:

a self-diagnosis electrode provided on the semiconductor chip;

an amplifier configured to amplify a detection signal obtained by converting changes in capacitance between the self-diagnosis electrode and the movable electrode into an electric signal, the signal amplified by the amplifier being output as a self-diagnosis signal; and

a device configured to increase the amplification factor of the amplifier during self-diagnosis operation to a value greater than an amplification factor during non-self-diagnosis operation.

2. The acceleration sensor according to claim 1 further comprising a section for modifying offset drift in the amplified signal obtained by the amplifier during self-diagnosis operation.

3. The acceleration sensor according to claim 1, wherein the amplifier comprises an operational amplifier and said device comprises two resistors connected to the operational amplifier to provide a feedback loop, and a switch, one of the two resistors being connected to the operational amplifier through the switch so that the one of the two resistors can be disconnected.