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Method for calibrating accelerometer sensitivity

  • US 7,093,478 B2
  • Filed: 07/08/2004
  • Issued: 08/22/2006
  • Est. Priority Date: 07/08/2004
  • Status: Active Grant
First Claim
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1. A method of calibrating an accelerometer comprising:

  • a. providing the accelerometer comprising;

    i. a substrate;

    ii. a mass suspended over the substrate and movable relative to the substrate, the mass including a movable electrode;

    iii. a first fixed electrode suspended over the substrate and not movable relative to the substrate;

    iv. a second fixed electrode suspended over the substrate and not movable relative to the substrate, the movable electrode and the first and second fixed electrode forming a differential capacitor;

    v. an excitation and readout circuit coupled to the movable electrode and to the fixed electrodes to provide an amplified signal;

    vi. an actuator, the actuator suspended over the substrate, the actuator displacing the mass by electrical means when activated; and

    vii. a spring suspended over the substrate connected to the mass, the spring and the actuator laid out such that a dimensional relationship is established between the actuator and the spring;

    b. measuring the resonant frequency of the mass;

    c. displacing the mass with the actuator;

    d. measuring the change in the amplified signal; and

    e. calculating the sensitivity of the accelerometer including calculating an acceleration equivalent to displacing the mass with the actuator wherein calculating the acceleration includes calculating a function of the resonant frequency, the form of the function determined by the dimensional relationship between the actuator and the spring.

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