SELF-TUNING EXTERNAL DEVICE FOR WIRELESSLY RECHARGING IMPLANTABLE MEDICAL DEVICES
First Claim
1. A method of providing recharge energy from an external device to an implantable medical device where the external device emits the recharge energy from a coil of a tank circuit, comprising:
- determining when current is naturally changing direction within the tank circuit of the external device; and
driving current through the tank circuit in a first direction based on the determination of when the current in the tank circuit is naturally changing to the first direction.
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Accused Products
Abstract
External device circuitry self-tunes so that current is being driven through a coil at a resonant frequency of the tank circuit including the coil. The self-tuning nature of the driver circuitry enables adaptation within a cycle to changes in the resonant frequency such as those due to changing loads on the coil from environmental factors. The self-tuning circuitry monitors the direction of current flow in the tank circuit so that during a non-driven phase of a two-phase cycle, the circuitry detects the current naturally changing directions and then activates the driver circuitry to drive current into the tank circuit in phase with the natural direction of current flow. Unity power factor is approximated while driving the coil despite changes in resonance. Power being driven into the tank circuit may then be measured at the approximation of unity power factor to control the amount of power being applied.
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Citations
29 Claims
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1. A method of providing recharge energy from an external device to an implantable medical device where the external device emits the recharge energy from a coil of a tank circuit, comprising:
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determining when current is naturally changing direction within the tank circuit of the external device; and driving current through the tank circuit in a first direction based on the determination of when the current in the tank circuit is naturally changing to the first direction. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. An external device for interacting with an implantable medical device, comprising:
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a voltage source; a tank circuit including a coil that emits recharge energy that may be received by the implantable medical device, the tank circuit having a first node and a second node; first and second switches connected to the first node of the tank circuit, the first switch being connected between the voltage source and the first node and the second switch being connected between the first node and the ground reference; a pair of diodes oppositely oriented in parallel between the second node of the tank circuit and a ground reference; and a control circuit connected to the second node of the tank circuit and to the first and second switches to control the state of the switches based on the direction of current flowing in the tank circuit, the control circuit activating the first switch and deactivating the second switch in relation to a first direction of current within the tank circuit and deactivating the first switch and activating the second switch in relation to a second direction of current within the tank circuit. - View Dependent Claims (10, 11, 12, 13, 14, 15)
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16. A method of providing recharge energy from an external device to an implantable medical device where the external device emits recharge energy from a coil of a tank circuit, comprising:
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monitoring an electrical characteristic of the tank circuit of the external device during a first phase of a first two-phase cycle while current flows in the tank naturally during the first phase; and driving current through the tank circuit during a second phase of the first two-phase cycle based on the electrical characteristic being monitored during the first phase to approximate unity power factor during the second phase of the first two-phase cycle. - View Dependent Claims (17, 18)
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19. An external device for interacting with an implantable medical device, comprising:
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a voltage source; a tank circuit including a coil that emits recharge energy that may be received by the implantable medical device, the tank circuit having a first node and a second node; first and second switches connected to the first node of the tank circuit, the first switch being connected between the voltage source and the first node and the second switch being connected between the first node and the ground reference; a pair of diodes oppositely oriented in parallel between the second node of the tank circuit and a ground reference; and a control circuit connected to the second node of the tank circuit and to the first and second switches to control the state of the switches by monitoring an electrical characteristic of the tank circuit at least during a first phase of a first two-phase cycle while current flows in the tank naturally so as to maintain an approximation of unity power factor when driving current from the voltage source into the tank circuit during a second phase of the first two-phase cycle. - View Dependent Claims (20)
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21. A method of providing recharge energy from an external device to an implantable medical device where the external device emits recharge energy from a coil of a tank circuit, comprising:
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while maintaining an approximation of unity power factor across the tank circuit of the external device for a driven phase of each two-phase cycle of the tank circuit, measuring electrical characteristics of energy in the tank circuit for each cycle; and controlling the amount of power being driven into the tank circuit during the driven phase based on the measured electrical characteristics. - View Dependent Claims (22, 23, 24, 25, 26, 27)
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28. An external device for interacting with an implantable medical device, comprising:
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a voltage source; a tank circuit including a coil that emits recharge energy that may be received by the implantable medical device, the tank circuit having a first node and a second node; first and second switches connected to the first node of the tank circuit, the first switch being connected between the voltage source and the first node and the second switch being connected between the first node and the ground reference; a pair of diodes oppositely oriented in parallel between the second node of the tank circuit and a ground reference; a control circuit connected to the second node of the tank circuit and to the first and second switches to control the state of the switches so as to maintain an approximation of unity power factor when driving the tank circuit for a first phase of a two-phase cycle; and a controller that measures electrical characteristics of energy in the tank circuit for each cycle and controls the amount of power being driven into the tank circuit from the voltage source during the driven phase based on the measured electrical characteristics. - View Dependent Claims (29)
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Specification