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Glass-break detector and method of alarm discrimination

  • US 6,538,570 B1
  • Filed: 06/22/2000
  • Issued: 03/25/2003
  • Est. Priority Date: 05/07/1999
  • Status: Expired due to Term
First Claim
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1. An apparatus for detecting the breaking of a contact-sensitive surface, comprising:

  • (a) an acoustic transducer;

    (b) a detector circuit responsive to the transducer for detecting an acoustic wave resulting from a contact force applied to the surface and generating a signal representing said acoustic wave, said signal having a plurality of consecutive amplitude peaks of the same or opposite phases; and

    (c) means for (i) scaling the amplitude of a first peak by a scaling factor less than one to establish a threshold level;

    (ii) comparing the amplitude of a amplitude peak following said first peak to the threshold level; and

    (iii) disqualifying the contact force as a breakage event if the amplitude of the second peak is greater than the threshold level and the second peak occurs within a time window initiated by detection of the contact force.

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