Charger alignment in an implantable medical device system employing reflected impedance modulation
First Claim
1. A system, comprising:
- an implantable medical device, comprising;
a first coil configured to receive a magnetic field for providing power to the implantable medical device; and
at least one switch configured to modulate an impedance of the first coil during receipt of the magnetic field; and
an external charger, comprising;
a second coil configured to produce the magnetic field;
an alignment detector configured to measure an electrical parameter of the second coil and to assess at least a magnitude of the measured electrical parameter and a magnitude of a change in the measured electrical parameter caused by modulation of the impedance of the first coil; and
at least one alignment indicator configured to indicate the alignment between the external charger and the implantable medical device based upon the magnitude of the measured electrical parameter and the magnitude of the change in the measured electrical parameter.
1 Assignment
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Accused Products
Abstract
The disclosed means of determining alignment between an external charger and an implantable medical device (IMD) 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 IMD. During charging, the charging coil in the IMD is pulsed to modulate its impedance. The difference in the coil voltage (ΔV) produced at the external charger as a result of these pulses is assessed and is used by the external charger to indicate coupling. If the magnitude of ΔV is above a threshold, the external charger considers the coupling to the IMD to be adequate, and an alignment indicator in the external charger is controlled accordingly. The magnitude of Vcoil can be assessed in addition to ΔV to determine alignment with the IMD with improved precision, and/or to further define a high quality alignment condition.
27 Citations
16 Claims
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1. A system, comprising:
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an implantable medical device, comprising; a first coil configured to receive a magnetic field for providing power to the implantable medical device; and at least one switch configured to modulate an impedance of the first coil during receipt of the magnetic field; and an external charger, comprising; a second coil configured to produce the magnetic field; an alignment detector configured to measure an electrical parameter of the second coil and to assess at least a magnitude of the measured electrical parameter and a magnitude of a change in the measured electrical parameter caused by modulation of the impedance of the first coil; and at least one alignment indicator configured to indicate the alignment between the external charger and the implantable medical device based upon the magnitude of the measured electrical parameter and the magnitude of the change in the measured electrical parameter. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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Specification