Spinal cord stimulator system
A wireless charger system for inductively charging a rechargeable battery of an implantable pulse generator (IPG) implanted in a human body is provided. A charging coil in the charger is wirelessly coupled to a receiving coil of the IPG to charge the rechargeable battery. An end-of-charge (EOC) circuit continuously monitors the reflected impedance from a reflected impedance sensor and determines the end of charge when a predetermined pattern of the reflected impedance corresponding to an EOC signal from the IPG is received. Advantageously, receiving the EOC signal through the charging coil eliminates the need to provide a separate communication circuit in the IPG that communicates with the charger.
1. A method for a wireless charger system for inductively charging a rechargeable battery of an implantable pulse generator (IPG) that generates stimulation signals for delivery to portions of a human body, the method comprising:
applying a charging signal that inductively charges the rechargeable battery of the IPG;
continuously monitoring a reflected impedance from a reflected impedance sensor while the charging signal is being applied; and
determining an end-of-charge (EOC) when a predetermined pattern of the reflected impedance corresponding to an EOC signal from the IPG is received.
2. The method of claim 1 , further comprising:
electrically shorting to ground a receiving coil of the IPG in a selected pattern corresponding to the predetermined pattern of the reflected impedance.
3. The method of claim 2 , wherein the step of electrically shorting includes switching by a processor a switch connected between the receiving coil and ground a selected number of times which is indicative of the EOC signal from the IPG.
4. The method of claim 3 , wherein the step of electrically shorting includes switching by a processor a switch connected between the receiving coil and ground at least three times.
5. The method of claim 4 , further comprising varying by the IPG the current being received by the receiving coil in a selected pattern corresponding to the predetermined pattern of the reflected impedance.
6. The method of claim 5 , further comprising outputting a tactile signal indicative of the EOC of the IPG when the EOC has been determined.
7. The method of claim 6 , further comprising:
outputting both a tactile signal and an audible signal indicative of the EOC of the IPG when the EOC has been determined.
8. The method of claim 7 , further comprising wherein when the EOC has been determined, turning off current to the charging coil.
9. The method of claim 1 , wherein the charging coil is backed by a ferrite plate.
10. The method of claim 1 , further comprising the step of reducing losses in the wireless charging system during recharging.
11. A method for a wireless charger system for inductively charging a rechargeable battery of an implantable pulse generator (IPG) that generates stimulation signals for delivery to portions of a human body, the method comprising:
applying a charging signal that inductively charges the rechargeable battery of the IPG;
continuously monitoring a reflected impedance from a reflected impedance sensor while the charging signal is being applied;
determining an end-of-charge (EOC) when a predetermined pattern of the reflected impedance corresponding to an EOC signal from the IPG is received; and
reducing losses in the wireless charging system.
12. The method of claim 1 , further comprising:
electrically shorting to ground a receiving coil of the IPG in a selected pattern corresponding to the predetermined pattern of the reflected impedance.
13. The method of claim 2 , wherein the step of electrically shorting includes switching by a processor a switch connected between the receiving coil and ground a selected number of times which is indicative of the EOC signal from the IPG.
14. The method of claim 3 , wherein the step of electrically shorting includes switching by a processor a switch connected between the receiving coil and ground at least three times.
15. The method of claim 4 , further comprising varying by the IPG the current being received by the receiving coil in a selected pattern corresponding to the predetermined pattern of the reflected impedance.
16. The method of claim 5 , further comprising outputting a tactile signal indicative of the EOC of the IPG when the EOC has been determined.
17. The method of claim 6 , further comprising:
outputting both a tactile signal and an audible signal indicative of the EOC of the IPG when the EOC has been determined.
18. The method of claim 7 , further comprising wherein when the EOC has been determined, turning off current to the charging coil.
19. The method of claim 1 , wherein the charging coil is backed by a ferrite plate.
20. The method of claim 11 , wherein the step of reducing losses in the wireless charging system during recharging is performed by a feedback closed look control.