Implant telemetry system
First Claim
1. An apparatus for communicating variable information to an external device from an electronic stimulator implanted in a living human patient, comprisingan external unit including means for transmitting a carrier signal,a hermetically sealed fully implantable enclosure adapted to be implanted at a fixed location in the patient'"'"'s body, means within said enclosure for generating stimulator outputs,a transponder within said enclosure including tuned resonant circuit means for resonating at the frequency of said carrier signal so as to re-radiate a signal at the frequency of said carrier signal, and means for superimposing an information signal on the reflected signal by altering the resonance of said tuned circuit means in accordance with an information signal,said superimposing means including a variable impedance load connected across said tuned circuit and means for varying the impedance of said load in accordance with an information signal,said external unit further including pickup means for receiving the reflected signal from said transponder and means for recovering the information signal superimposed thereon,said receiving means including means reponsive to said reflected signal from said transponder for producing on associated analog output signal, andsaid recovering means including phase shift detector means responsive to said analog output signal for producing an output signal related to the relative phase angle thereof.
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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.
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Citations
30 Claims
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1. An apparatus for communicating variable information to an external device from an electronic stimulator implanted in a living human patient, comprising
an external unit including means for transmitting a carrier signal, a hermetically sealed fully implantable enclosure adapted to be implanted at a fixed location in the patient'"'"'s body, means within said enclosure for generating stimulator outputs, a transponder within said enclosure including tuned resonant circuit means for resonating at the frequency of said carrier signal so as to re-radiate a signal at the frequency of said carrier signal, and means for superimposing an information signal on the reflected signal by altering the resonance of said tuned circuit means in accordance with an information signal, said superimposing means including a variable impedance load connected across said tuned circuit and means for varying the impedance of said load in accordance with an information signal, said external unit further including pickup means for receiving the reflected signal from said transponder and means for recovering the information signal superimposed thereon, said receiving means including means reponsive to said reflected signal from said transponder for producing on associated analog output signal, and said recovering means including phase shift detector means responsive to said analog output signal for producing an output signal related to the relative phase angle thereof.
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12. Telemetry apparatus for an active physiological implant of the type which has means for stimulating tissue with electrical impulses having a variety of programmable operating parameters, comprising
an implantable enclosure, a coil tuned to a frequency in the upper audio band mounted within said enclosure, and a low impedance shunt circuit connected across said tuned coil including semiconductor means for modulating the impedance of said shunt circuit in accordance with a digital information signal representing the value of an operating parameter of the implant to alter the phase and amplitude of a signal reradiated by said tuned coil in the presence of an externally generated magnetic carrier signal at the frequency to which said coil is tuned.
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15. Implantable telemetry apparatus comprising
an implantable enclosure, and a coil tuned to a frequency in the upper audio band mounted within said enclosure, a low impedance shunt circuit connected across said tuned coil including semiconductor means for modulating the impedance of said shunt circuit in accordance with a digital information signal to alter the phase and amplitude of a signal reradiated by said tuned coil in the presence of an externally generated magnetic carrier signal at the frequency to which said coil is tuned, said semiconductor means including a pair of series opposed transistors having respective gate terminals operatively connected to be driven by a digital information signal.
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18. Implantable telemetry apparatus comprising
an implantable enclosure, a coil tuned to a frequency in the upper audio band mounted within said enclosure, a low impedance shunt circuit connected across said tuned coil including semiconductor means for modulating the impedance of said shunt circuit in accordance with a digital information signal to alter the phase and amplitude of a signal reradiated by said tuned coil in the presence of an externally generated magnetic carrier signal at the frequency to which said coil is tuned, and optical receiving means mounted within said enclosure for producing an output signal in response to light levels indicative of optically transmitted information from outside the enclosure, means in said enclosure responsive to the voltage induced across said tuned coil exceeding a threshold level for activating said optical receiving means.
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19. Implantable telemetry apparatus, comprising
an implantable enclosure, inductor means in said enclosure for developing an induced voltage in the presence of a varying magnetic field, optical receiving means in said enclosure for producing an output signal in response to light levels indicative of an optically transmitted information signal from outside the enclosure, and means responsive to said induced voltage exceeding a threshold level for activating said optical receiving means.
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21. Apparatus for communicating variable information from an external device to an electronic stimulator implanted in a living human patient comprising
an implantable impermeable enclosure metal having an optically transparent window formed therein, means within said enclosure for generating stimulator outputs, a photosensitive element mounted in said metal enclosure directly beneath said window, and data processing means connected to receive the output of said photosensitive element for reproducing a data signal received by said element.
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23. An apparatus for communicating variable information between an external device and an electronic stimulator implanted in a living human patient, comprising
an external unit including means for radiating a carrier signal and other means for transmitting a signal in accordance with a first information signal, a hermetically sealed fully implantable enclosure adapted to be implanted at a fixed location in the patient'"'"'s body, means within said enclosure for generating stimulator outputs, receiving means within said enclosure responsive to said transmitted signal for producing an associated first information output signal, a transponder within said enclosure including tuned resonant circuit means for resonating at the frequency of said carrier signal so-as to re-radiate a signal at the frequence of said carrier signal, and means for superimposing an information signal on the reflected signal by altering the resonance of said tuned circuit means in accordance with a second information signal, said external unit further including pickup means for receiving the reflected signal from said transponder and means for recovering the second information signal superimposed thereon, said receiving means including means responsive to said reflected signal from said transponder for producing an associated analog output signal, and said recovering means including phase shift detector means responsive to said analog output signal for producing an output signal related to the relative phase angle thereof.
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25. A two-way multimode implant communications system, comprising
an external unit having means for radiating a magnetic field oscillating at a carrier frequency and other means for transmitting a signal in accordance with a first information signal, and an implantable unit having receiving means responsive to said transmitted signal for producing an associated first information output signal, tuned coil means responsive to the carrier frequency of said magnetic field for reradiating a signal at the carrier frequency with a phase shift, a variable impedance load across said coil means and means for modulating said variable impedance load in accordance therewith, said external unit further including receiver means responsive to the reradiated signal from said implantable unit for producing a second information output, wherein said transmitting means of said external unit includes both means for transmitting an optical signal in accordance with said first information input signal and reed switch coil means for transmitting magnetic pulses in accordance with said first information signal.
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29. A two-way multimode implant communications system, comprising
an external unit having means for radiating a magnetic field oscillating at a carrier frequency and other means for transmitting a signal in accordance with a first information signal, and an implantable unit having receiving means responsive to said transmitted signal for producing an associated first information output signal, tuned coil means responsive to the carrier frequency of said magnetic field for reradiating a signal at the carrier frequency with a phase shift, a variable impedance load across said coil means and means for modulating said variable impedance load in accordance therewith, said external unit further including receiver means responsive to the reradiated signal from said implantable unit for producing a second information output, wherein said transmitting means of said external unit includes an optical transmitting means, and said receiving means of said implantable unit includes an optical receiving means.
Specification