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Inertial Sensor

  • US 20130133422A1
  • Filed: 08/08/2011
  • Published: 05/30/2013
  • Est. Priority Date: 08/11/2010
  • Status: Active Grant
First Claim
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1. An inertial sensor, comprising:

  • a first substrate;

    a first cavity formed on the first substrate;

    a first fixed part formed in the first cavity;

    a first elastically deformed part formed in the cavity and connected to the fixed part;

    a first movable part formed in the first cavity and connected to the elastically deformed part;

    a first capacity sensing element which includes a first capacitative element that mutually opposes a first fixed electrode formed in the first cavity and a first movable electrode formed in the movable part and which outputs the variation of the capacity of the first capacitative element caused when the movable part is displaced by external force;

    a first physical quantity calculation terminal connected to a first physical quantity calculating device that calculates the physical quantity of the external force based upon the variation of the capacity output from the first capacity sensing element;

    a forced oscillation generating device which includes a second capacitative element that mutually opposes a second fixed electrode formed in the first cavity and a second movable electrode formed in the movable part, which includes a terminal for applying a diagnostic signal for applying a diagnostic signal between the second fixed electrode and the second movable electrode and which generates electrostatic force between the second fixed electrode and the second movable electrode by applying a diagnostic signal to the terminal for applying the diagnostic signal and forcedly oscillates them;

    an abnormality determination device which is indirectly connected to the first physical quantity calculation terminal and which judges whether the first capacity sensing element is abnormal or not based upon forced oscillation generated in the forced oscillation generating device;

    a second substrate installed in the same vehicle as the first substrate;

    a second cavity formed on the second substrate;

    a second fixed part formed in the second cavity;

    a second elastically deformed part formed in the second cavity and connected to the second fixed part;

    a second movable part formed in the second cavity and connected to the second elastically deformed part;

    a second capacity sensing element which includes a third capacitative element that mutually opposes a third fixed electrode formed in the second cavity and a third movable electrode formed in the second movable part and which outputs the variation of the capacity of the third capacitative element caused when the second movable part is displaced by external force; and

    a second physical quantity calculation terminal connected to a second physical quantity calculating device that calculates the physical quantity of the external force based upon the variation of the capacity output from the second capacity sensing element, wherein;

    in the abnormality determination device, a result of determining abnormality is varied depending upon a value acquired from the second physical quantity calculation terminal.

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