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Acoustic signalling apparatus for implantable devices

  • US 4,481,950 A
  • Filed: 04/03/1981
  • Issued: 11/13/1984
  • Est. Priority Date: 04/27/1979
  • Status: Expired due to Term
First Claim
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1. Acoustic end of battery life signalling apparatus for an implantable pacemaker which has a battery and a housing, comprising:

  • (a) a transducer for generating acoustic signals in response to applied electrical signals;

    (b) means mounting said transducer in said pacemaker adjacent the housing of the pacemaker;

    (c) an oscillator circuit operable when energized to apply electrical signals to the transducer;

    (d) an energy storage capacitor;

    (e) first switching means connected for selectively charging the energy storage capacitor from the battery of the pacemaker, said switching means connected for switching on in response to pulses from an output of the stimulating pulse generating circuit of the pacemaker;

    (f) battery end-of-life detection means for producing a signal in response to a drop in the output of the pacemaker battery to a predetermined level;

    (g) further switching means selectively connecting said energy storage capacitor to said oscillator circuit, and means connecting said further switching means for control by the signal produced by the end-of-life detector, whereby the acoustic signalling apparatus is enabled to transmit acoustic pulses warning of the end of battery life.

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