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Movement detector and apnea monitor including same

  • US 5,271,412 A
  • Filed: 05/07/1992
  • Issued: 12/21/1993
  • Est. Priority Date: 05/23/1991
  • Status: Expired due to Term
First Claim
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1. A movement detector comprising a piezoelectric crystal transducer outputting electrical signals in response to changes in force applied to its opposite faces;

  • a supporting member on one side of the transducer for supporting the transducer;

    a collector member on the opposite side of the transducer and having an effective area, as circumscribed by its outer edges, which is larger than that of the transducer, for collecting forces applied to the collector member and for applying them to said transducer;

    a spacer element between said collector member and said opposite side of the transducer and contacting said opposite side of the transducer over an area less than that side of the transducer, for directing the forces from said collector member to said transducer; and

    annular spacer means on the supporting member side of the transducer;

    said annular spacer means having an inner diameter slightly smaller than the diameter of the respective side of the transducer, and an outer diameter slightly larger than the respective side of the transducer.

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