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Magnetic field detector

  • US 5,662,694 A
  • Filed: 12/14/1995
  • Issued: 09/02/1997
  • Est. Priority Date: 12/15/1994
  • Status: Expired due to Fees
First Claim
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1. A combined telemetry and magnetic field detector unit for a medical implant, comprising:

  • a source of voltage;

    a telemetry circuit;

    a magnetic field detector;

    a coil containing a core and connected to said source of voltage and being connected to each of, and shared by, said telemetry circuit and said magnetic field detector;

    said telemetry circuit comprising means connected to said coil for transmitting and receiving telemetry signals via said coil;

    control means connected to said telemetry circuit and to said magnetic field detector for switching between a telemetry mode for transmitting or receiving said telemetry signals, and a magnetic field detection mode; and

    said magnetic field detector comprising means connected to said coil and to said source of voltage for, during said magnetic field detection mode, charging said coil with voltage from said source of voltage for a defined period of time and for subsequently discharging said coil, said coil having a discharge time associated therewith, and magnetic field indicator means for measuring said discharge time of said coil and for identifying a presence of a magnetic field in which said coil is disposed, and for generating a detection signal indicating the presence of said magnetic field, if said discharge time is less than a defined time threshold value.

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