Closed Loop Charger for an Implantable Medical Device System Employing Reflected Impedance Modulation
First Claim
1. An external charger for an implantable medical device, comprising:
- a coil for producing a magnetic field for providing power to the implantable medical device;
a detector for receiving an electrical parameter of the coil, wherein the detector determines at least a magnitude of a change in the electrical parameter, wherein the change is inducible by the implantable medical device; and
charging circuitry coupled to the coil, wherein the charging circuitry controls a strength of the magnetic field at least in accordance with the magnitude of the change.
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Accused Products
Abstract
The disclosed system for providing closed loop charging between an external charger and an implantable medical device such as an IPG involves the use of reflected impedance modulation, i.e., by measuring at the external charger reflections arising from modulating the impedance of the charging coil in the IPG. During charging, the charging coil in the IPG is periodically pulsed to modulate its impedance. The magnitude of the change in the coil voltage produced at the external charger ΔV as a result of these pulses is assessed and is used by the controller circuitry in the external charger as indicative of the coupling between the external charger and the IPG. The external charger adjusts its output power (e.g., Icharge) in accordance with the magnitude of ΔV, thus achieving closed loop charging without the need of telemetering coupling parameters from the IPG.
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Citations
33 Claims
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1. An external charger for an implantable medical device, comprising:
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a coil for producing a magnetic field for providing power to the implantable medical device; a detector for receiving an electrical parameter of the coil, wherein the detector determines at least a magnitude of a change in the electrical parameter, wherein the change is inducible by the implantable medical device; and charging circuitry coupled to the coil, wherein the charging circuitry controls a strength of the magnetic field at least in accordance with the magnitude of the change. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A system, comprising:
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an implantable medical device, comprising; a first coil for receiving a magnetic field for providing power to the implantable medical device; and at least one switch for modulating an impedance of the first coil during receipt of the magnetic field; and an external charger, comprising; a second coil for producing the magnetic field; a detector for receiving an electrical parameter of the second coil, wherein the detector determines at least a magnitude of a change in the electrical parameter caused by modulation of the impedance of the first coil; and charging circuitry coupled to the coil, wherein the charging circuitry controls a strength of the magnetic field at least in accordance with the magnitude of the change. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26)
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27. A method for providing power to an implantable medical device from an external charger, comprising:
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providing a magnetic field from a second coil in an external charger; modulating an impedance of a first coil in the implantable medical device while receiving the magnetic field from the external charger; determining at least a magnitude of a change in an electrical parameter of the second coil in the external charger caused by modulating the impedance of the first coil; and adjusting a strength of the magnetic field provided by the second coil in accordance with at least the magnitude of the change. - View Dependent Claims (28, 29, 30, 31, 32, 33)
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Specification