Closed loop charger for an implantable medical device system employing reflected impedance modulation
First Claim
1. A method for providing power to an implantable medical device from an external charger, comprising:
- 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 second coil;
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;
obtaining a value of a charging parameter using the determined magnitude of the change in the electrical parameter via an established relationship between corresponding charging parameter values and magnitudes of change in the electrical parameter; and
adjusting a strength of the magnetic field provided by the second coil in accordance with the obtained value of the charging parameter.
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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
13 Claims
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1. 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 second coil; 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; obtaining a value of a charging parameter using the determined magnitude of the change in the electrical parameter via an established relationship between corresponding charging parameter values and magnitudes of change in the electrical parameter; and adjusting a strength of the magnetic field provided by the second coil in accordance with the obtained value of the charging parameter. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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Specification