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Micro-machined accelerometer

  • US 4,922,756 A
  • Filed: 06/20/1988
  • Issued: 05/08/1990
  • Est. Priority Date: 06/20/1988
  • Status: Expired due to Term
First Claim
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1. A transducer comprising,a movable mass supported by springs from a support structure;

  • said mass having a surface with a sense conducting area and a force conducting area, said mass being free to move between corresponding first and second sense conducting areas and first and second force conducting areas on plates which face said surface of said mass and which are secured to said support structure, said sensing conducting areas and said force conducting areas being electrically isolated from each other;

    means for applying a first voltage between said first and second sense conducting areas of said plates thereby creating a sense electric field between said sense conducting areas and inducing a sense voltage on said mass sense conducting area of said mass surface proportional to the displacement of said mass surface between said plates,means for applying a second voltage between said first and second force conducting areas of said plates thereby creating a force electric field between said force conducting areas,forward circuit means responsive to said sense voltage for generating a displacement signal representative of the distance said mass has moved from a reference position between said plates, andfeedback circuit means responsive to said displacement signal for applying an amount of electric charge proportional to the level of said displacement signal on said force conducting area of said mass surface such that a force is created on said mass proportional to the numerical product of said amount of charge and said force electric field in a direction to restore said mass to said reference position.

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