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Force sensing device

  • US 4,970,903 A
  • Filed: 06/30/1989
  • Issued: 11/20/1990
  • Est. Priority Date: 10/22/1987
  • Status: Expired due to Term
First Claim
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1. A force sensing device, comprising:

  • (a) a pair of substantially identical, adjacent and parallel elongated vibratable tines;

    (b) means for vibrating said tines back and forth at the same frequency but 180°

    out of phase with one another in a common plane and in a direction normal to the elongation axis of the tines;

    (c) an arrangement including four substantially identical links located in said common plane and means interconnecting the links to one another and to opposite ends of said tines so as to form a parallelogram such that the elongation axes of said tines extend between a first pair of opposing corners of the parallelogram, said arrangement including mounting means forming part of said interconnecting means and located at a second pair of opposing corners of said parallelogram for connecting the arrangement to an external member capable of applying a variable external force to the support arrangement along an axis extending through the second pair of corners of said parallelogram such that the arrangement applies to said tines its own internal force in response to and varying with said external force and causes the tines to vibrate at a frequency that varies with the magnitude of said internal force and therefore said external force; and

    (d) means for sensing the vibrating frequency of at least one of said tines for determining therefrom the magnitude of said external force;

    (e) said tines and links and said interconnecting means being integrally formed as a single unit of quartz crystal material; and

    (f) said means interconnecting said links to opposite ends of said tines including a pair of quartz crystal members separate from but integrally formed with said tines and said links, each of said members connecting a respective one of the pair of adjacent ends of said tines together and to an adjacent one of said opposing corners.

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