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Apparatus for determining pen acceleration

  • US 4,345,239 A
  • Filed: 06/20/1980
  • Issued: 08/17/1982
  • Est. Priority Date: 06/20/1980
  • Status: Expired due to Term
First Claim
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1. An apparatus for measuring pen acceleration for use in a signature verification system, comprising:

  • a pen having capacitive transducer means mounted therein for changing capacitance responsive to acceleration of said pen,a Blumlein bridge circuit having an input and an output and having one arm thereof comprised of the capacitance of said capacitive transducer means,amplifier means having an input connected to the output of said Blumlein bridge circuit, and having an output for providing an amplified signal, andA.M. detector means for detecting the modulation on said amplified signal, which corresponds to said acceleration.

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