Telemetry means for tissue stimulator system
First Claim
1. In a living tissue stimulator system comprising an implantable tissue stimulator and an external receiving means, a telemetry means comprising:
- a first oscillator means;
a first LC circuit coupled to said first oscillator means;
an impedance reflecting circuit in magnetically coupled relationship to said first LC circuit whereby the combined impedance of said first LC circuit and said impedance reflecting circuit combination is related to the impedance of said impedance reflecting circuit;
altering means for varying the impedance of said impedance reflecting circuit;
a second oscillator means having an output frequency related to a signal voltage to be telemetered; and
means for controlling said altering means by said second oscillator means whereby characteristics of an output signal from said first oscillator means are related to the impedance of said impedance reflecting circuit.
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Accused Products
Abstract
A telemetry system for use in a living tissue stimulator system in which an externally located oscillator is controlled by impedance changes in an impedance reflecting circuit located in an implantable tissue stimulator. In a first embodiment the impedance reflecting circuit is an LC circuit thereby frequency modulating the externally located oscillator and in a second embodiment it is an LR circuit thereby amplitude modulating the externally located oscillator. More specifically, the externally located oscillator drives an LC circuit in which the inductor is positioned in magnetically coupled relationship to an inductor in the impedance reflecting circuit. The externally located oscillator is chosen so that its frequency and amplitude is partially determined by the impedance of the LC circuit and the magnetically coupled impedance reflecting circuit. A parameter or signal to be telemetered, which could be in the form of a digital or an analog signal, is used to modulate an output frequency of a voltage controlled oscillator located in the implantable tissue stimulator. This frequency modulated output of the voltage controlled oscillator drives an FET switch which alters the impedance of the impedance reflecting circuit, thereby modulating the output of the externally located oscillator. Thus, a telemetry system is provided in which minimum power is required from the implantable tissue stimulator.
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Citations
32 Claims
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1. In a living tissue stimulator system comprising an implantable tissue stimulator and an external receiving means, a telemetry means comprising:
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a first oscillator means; a first LC circuit coupled to said first oscillator means; an impedance reflecting circuit in magnetically coupled relationship to said first LC circuit whereby the combined impedance of said first LC circuit and said impedance reflecting circuit combination is related to the impedance of said impedance reflecting circuit; altering means for varying the impedance of said impedance reflecting circuit; a second oscillator means having an output frequency related to a signal voltage to be telemetered; and means for controlling said altering means by said second oscillator means whereby characteristics of an output signal from said first oscillator means are related to the impedance of said impedance reflecting circuit. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. In combination with a living tissue stimulator system comprising an implantable tissue stimulator and an external receiving means, a telemetry system comprising:
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a first oscillator located in said external receiving means; an impedance creating circuit comprising a first inductor coupled to said first oscillator and partially determinative of said first oscillator signal characteristics; an impedance reflecting circuit comprising a second inductor in magnetically coupled relationship to said first inductor and located in said implantable tissue stimulator; a voltage controlled oscillator having an output frequency related to a signal to be telemetered; and control means for altering impedance characteristics of said impedance reflecting circuit in relation to said voltage controlled oscillator output voltage, thereby altering said first oscillator signal characteristics. - View Dependent Claims (14, 15, 16)
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17. In combination with a living tissue stimulator system comprising an implantable tissue stimulator and an external receiving means, an FM/FM telemetry system comprising:
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a first oscillator located in said external receiving means; an impedance creating circuit comprising a first inductor coupled to said first oscillator and partially determinative of said first oscillator frequency; an impedance reflecting circuit comprising a capacitor and a second inductor in magnetically coupled relationship to said first inductor and located in said implantable tissue stimulator; a voltage controlled oscillator having an output frequency related to a signal to be telemetered; and control means for altering impedance characteristics of said impedance reflecting circuit in relation to said voltage controlled oscillator output voltage, thereby altering the output signal frequency of said first oscillator. - View Dependent Claims (18, 19, 20)
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21. In combination with a living tissue stimulator system comprising an implantable tissue stimulator and an external receiving means, an FM/AM telemetry system comprising:
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a first oscillator located in said external receiving means; an impedance creating circuit comprising a first inductor coupled to said first oscillator; an impedance reflecting circuit comprising a resistor and a second inductor in magnetically coupled relationship to said first inductor and located in said implantable tissue stimulator; a voltage controlled oscillator having an output frequency related to a signal to be telemetered; and control means for altering impedance characteristics of said impedance reflecting circuit in relation to said voltage controlled oscillator output voltage, thereby altering the output signal amplitude of said first oscillator. - View Dependent Claims (22, 23, 24)
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25. A method for telemetering information from an implantable living tissue stimulator to a receiving means, the steps comprising:
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varying the frequency of a voltage controlled oscillator in said implantable living tissue stimulator in relation to a signal to be telemetered; altering the impedance of an impedance reflecting circuit comprising a first inductor in relation to said voltage controlled oscillator output voltage; magnetically coupling said first inductor to a second inductor coupled to an external oscillator located in said receiving means whereby an output signal of said external oscillator is related to the impedance of said impedance reflecting circuit. - View Dependent Claims (26, 27)
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28. In combination with an implantable device for humans having an impedance reflecting circuit and an external receiving means, a telemetry system comprising:
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means for altering the impedance of said impedance reflecting circuit in relation to a signal to be telemetered from said device, said impedance reflecting circuit comprising a first inductor; a second inductor in magnetically coupled relationship to said first inductor; and said external receiving means comprises impedance sensing means connected to said second inductor for providing an output signal responsive to impedance changes in said impedance reflecting circuit, said output signal being related to said signal to be telemetered. - View Dependent Claims (29, 30, 31, 32)
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Specification