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GRA MEMS ACCELEROMETER

  • US 20090007667A1
  • Filed: 07/26/2006
  • Published: 01/08/2009
  • Est. Priority Date: 07/26/2005
  • Status: Active Grant
First Claim
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1. An accelerometer that lies generally in a plane, for detecting acceleration along an input axis that is orthogonal to the plane of the accelerometer, comprising:

  • a substrate defining a surface;

    spaced bonding pads coupled to the substrate and projecting from the surface of the substrate;

    a generally planar Servo Member (SM) spaced from and essentially parallel to the surface of the substrate and flexibly coupled to the bonding pads by servo member flexures such that the servo member is capable of oscillatory motion relative to the substrate about a servo axis that is in the plane of the servo member;

    a generally planar plate Torque Summing Member (TSM) located within, coplanar with, and flexibly coupled to the SM such that the TSM is capable of rotational motion relative to the substrate about an output axis that is in the plane of the TSM and orthogonal to the servo axis, the TSM being mass-imbalanced relative to the output axis;

    a generally planar plate rotor located within coplanar with, and flexibly coupled to the TSM such that the rotor is capable of rotary oscillatory motion relative to the TSM about a rotor axis that is orthogonal to the plane of the rotor, the torque summing member and the servo member;

    one or more rotor drives for directly oscillating the rotor about the rotor axis at a rotor oscillation frequency and amplitude;

    one or more SM drives for oscillating the SM about the servo axis at a servo member oscillation frequency and amplitude, and thereby also oscillating the rotor and torque summing member about the servo axis at the servo member oscillation frequency;

    one or more rotor motion sensors that detect oscillation of the rotor relative to the substrate about the rotor axis;

    one or more SM motion sensors that detect oscillation of the SM relative to the substrate about the servo axis; and

    one or more TSM motion sensors that detect rotation of the TSM relative to the substrate about the output axis.

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