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Acceleration detector

  • US 5,485,749 A
  • Filed: 05/18/1994
  • Issued: 01/23/1996
  • Est. Priority Date: 05/26/1993
  • Status: Expired due to Term
First Claim
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1. An acceleration detector for independently detecting three-dimensional components of acceleration applied thereto with respect to X-, Y- and Z-axes of an orthogonal coordinate system, said acceleration detector comprising:

  • a frame defining an open space therein and having a top face and a bottom face, said frame being made of a semi-conductor material;

    a thin-sheet resilient member made of the same semi-conductor material as said frame to extend in a plane over said open space and integrally joining at a periphery of said resilient member to the top face of said frame, said X- and Y-axes being defined to extend in the plane of said resilient member;

    a weight made of the same semi-conductor material as said frame to depend from a center of said resilient member through a neck portion, said neck portion being fixed only with a center portion of said resilient member in such a manner that an elastic deformation of said resilient member will occur when said weight is displaced with respect to said frame by receiving said acceleration, said center portion being defined as a region of said resilient member corresponding to an interface between said resilient member and said neck portion;

    a plurality of piezo resistance elements formed in said resilient member, the resistance of which varies in response to strain and elastic deformation of said resilient member, said resistance elements consisting of a first set of four resistance elements for detecting a first component of said acceleration with respect to said X-axis, a second set of four resistance elements for detecting a second component of said acceleration with respect to said Y-axis, and a third set of four resistance elements for detecting a third component of said acceleration with respect to said Z-axis, all of said resistance elements of said first and second sets being located within an inner area of said resilient member immediately adjacent to a circumference of said center portion such that one end of each of the resistance elements of the first and second sets reaches the circumference of said center portion, said inner area being capable of a larger elastic deformation than an outer area of said resilient member adjacent to said frame when said weight is displaced by receiving an acceleration having a horizontal direction parallel to said plane of said resilient member; and

    acceleration determining means for determining said acceleration in accordance with a variation of electric resistance of said resistance elements.

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