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Detector for a physical quantity having a self-testing function

  • US 5,492,020 A
  • Filed: 11/30/1992
  • Issued: 02/20/1996
  • Est. Priority Date: 03/30/1991
  • Status: Expired due to Term
First Claim
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1. A detector for a physical quantity having a self-testing function, the detector comprising:

  • a tubular detector casing;

    a continuous flexible substrate placed inside the casing, said flexible substrate having an outer peripheral portion supported by an inner wall of the casing;

    a fixed, rigid substrate placed inside the casing above said flexible substrate and fixed to the casing so as to face said flexible substrate with a spacing therebetween;

    a working body connected to a lower surface of said flexible substrate at a central portion thereof so that said flexible substrate is bent when a force caused by an external physical action is applied to said working body;

    a displacement electrode supported on an upper surface of said flexible substrate so as to be displaced when the flexible substrate is bent;

    a fixed electrode supported on a lower surface of said fixed substrate so as to face said displacement electrode;

    a test electrode supported on said lower surface of said fixed substrate so as to face said flexible electrode, said test electrode and said fixed electrode being electrically insulated from each other;

    detection means for generating an electric signal which indicates a change of an electrostatic capacitance between said displacement electrode and said fixed electrode; and

    voltage application means for applying a predetermined voltage across said test electrode and said displacement electrode for calibration purposes.

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