ALIGNMENT OF EXTERNAL DEVICE RELATIVE TO IMPLANTED DEVICE

The alignment and positioning of an external device relative to an internal device is indicated on a display and/or by an acoustical signal. In the disclosed application, the external device transcutaneously transmits electromagnetic energy to an internal receiver to provide electrical power for an implanted medical device. To ensure optimal coupling between the external transmitter and the internal receiver, two permanent magnets are disposed at spaced-apart positions on the internal receiver. The magnetic field strength of the permanent magnets is sensed by a pair of correspondingly spaced-apart Hall effect sensor on the external transmitter. As the external transmitter is moved about over the internal receiver, the signals produced by the Hall effect sensors drive a display of light emitting diodes (LEDs) that indicates when the maximum magnetic field strength is achieved, i.e., when the Hall effect sensors on the external transmitter are each positioned directly opposite the corresponding permanent magnets on the internal receiver.