Implant telemetry system
First Claim
1. External data telemetry apparatus for receiving data communications from a biomedical implant, comprisinga coil assembly having at least three coaxial spaced electrical coils,transmitter means operatively interconnected with a middle one of said coils for radiating a magnetic carrier signal,means for providing a pickup signal indicative of the difference between the voltages induced in at least one pair of other ones of said coils on opposite sides of said middle coil,phase shift detector means operatively connected to receive said pickup signal for producing an output signal level as a function of the relative phase angle of said pickup signal,and information signal processing means for digitally demodulating said output signal level to recover a digitally encoded data signal from said implant,whereby digitally modulated resonance within the implant is effectively employed as a low power communications medium.
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Accused Products
Abstract
An externally generated myriametric frequency magnetic carrier signal is resonantly reflected by a tuned coil in an implant. The lagging phase angle of the reflected signal is modulated at very low power by varying the impedance across the tuned coil in accordance with a data input signal. An external phase shift demodulator recovers the transmitted data. To assure adequate coupling between the external unit and the implant, the output level of an external phase comparator must exceed a given threshold to signify "acquisition" before data is transmitted from the implant. In a preferred embodiment, a shunt circuit across the tuned coil is opened and closed in accordance with a digital input signal generated by the implant. The external telemetry unit preferably includes a coaxially spaced triple coil assembly. The middle coil transmits the carrier. The outer pickup coils are balanced to minimize carrier reception. For two-way communication an IR transmitter is added to the coil assembly. During acquisition, the output of the tuned coil is used to turn on a dormant IR receiver in the implant. Light emitting diodes are preferably mounted in an array on the face of the coil assembly surrounded by an optional reed switch coil for multimode telemetry in the programmer.
224 Citations
21 Claims
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1. External data telemetry apparatus for receiving data communications from a biomedical implant, comprising
a coil assembly having at least three coaxial spaced electrical coils, transmitter means operatively interconnected with a middle one of said coils for radiating a magnetic carrier signal, means for providing a pickup signal indicative of the difference between the voltages induced in at least one pair of other ones of said coils on opposite sides of said middle coil, phase shift detector means operatively connected to receive said pickup signal for producing an output signal level as a function of the relative phase angle of said pickup signal, and information signal processing means for digitally demodulating said output signal level to recover a digitally encoded data signal from said implant, whereby digitally modulated resonance within the implant is effectively employed as a low power communications medium.
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19. External data telemetry apparatus for inbound telemetry to a biomedical implant, comprising
a movable handheld telemetry head with a substantially flat bottom surface, a plurality of light emitting elements arranged in said head adjacent to said flat surface in a circular array about a common axis, and drive means for pulsing said elements simultaneously in accordance with a variable information carrying data signal.
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21. External data telemetry apparatus for receiving data communications from a biomedical implant, comprising
a triple coil assembly having three coaxial spaced electrical coils, transmitter means operatively interconnected with the middle one of said coils for radiating a magnetic carrier signal, the other coils having corresponding ends electrically connected together in a series circuit, a pickup lead having one end connected to a junction between corresponding ends of said other coils, the other end of said pickup means providing a pickup signal indicative of the difference between the voltages induced in said other coils, information signal processing means connected to receive said pickup signal for demodulating the relative phase angle of said pickup signal to recover a transmitted data signal from said implant, whereby modulated resonance within the implant is effectively employed as a low power communications medium.
Specification