Inductive Charger with Magnetic Shielding

• US 20150224323A1
• Filed: 04/27/2015
• Published: 08/13/2015
• Est. Priority Date: 03/26/2010
• Status: Active Grant

• Current Assignee: Boston Scientific Neuromodulation Corporation (Boston Scientific Corporation)
• Original Assignee: Boston Scientific Neuromodulation Corporation (Boston Scientific Corporation)
• Inventors: Chen, Joey, Ozawa, Robert, Aghassian, Daniel
• Granted Patent: US 9,636,508 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: A61N 1/3758 Packaging of the components within the casing
• CPC Class Codes: A61N 1/3787 from an external energy source
• CPC Class Codes: H01F 27/36 Electric or magnetic shields or screens movable for varying inductance H01F21/10
• CPC Class Codes: H01F 27/366 made of ferromagnetic material
• CPC Class Codes: H01F 38/14 Inductive couplings for wireless supply or distribution of electric power using inductive coupling H02J50/10
• CPC Class Codes: H02J 2310/23 The load being a medical device, a medical implant, or a life supporting device
• CPC Class Codes: H02J 50/10 using inductive coupling
• CPC Class Codes: H02J 50/70 involving the reduction of electric, magnetic or electromagnetic leakage fields
• CPC Class Codes: H02J 7/0044 specially adapted for holding portable devices containing batteries H02J7/0045 takes precedence
• CPC Class Codes: H02J 7/342 The other DC source being a battery actively interacting with the first one, i.e. battery to battery charging with circuits for polarity protection H02J7/0034

Abstract

To recharge an implanted medical device, an external device, typically in the form of an inductive charger, is placed over the implant to provide for transcutaneous energy transfer. The external charging device can be powered by a rechargeable battery. Since the battery is in close proximity to the charge coil, the large magnetic field produced by the charge coil induces eddy currents that flow on the battery'"'"'s metallic case, often resulting in undesirable heating of the battery and reduced efficiency of the charger. This disclosure provides a means of shielding the battery from the magnetic field to reduce eddy current heating, thereby increasing efficiency. In one embodiment, the magnetic shield consists of one or more thin ferrite plates. The use of a ferrite shield allows the battery to be placed directly over the charge coil as opposed to outside the extent of the charge coil.

Claims

1. An external device for use with an implantable medical device, comprising:

a housing;

a coil within the housing;

a battery within the housing; and

a magnetic shield within the housing comprising a high permeability material,

wherein the coil, the magnetic shield, and the battery are aligned in a stack, wherein the magnetic shield is located between the battery and the coil in the stack, and

wherein the coil generates a magnetic field to provide power to the implantable medical device.

2. The device of claim 1, wherein the magnetic shield comprises a ferrite plate.

3. The device of claim 1, wherein the battery comprises a rechargeable Lithium-ion battery.

4. The device of claim 1, wherein the magnetic shield covers the entire extent of the coil.

5. The device of claim 1, wherein the coil, battery, and magnetic shield are co-axially aligned in the stack.

6. The device of claim 5, further comprising a printed circuit board (PCB) within the housing of the external device.

7. The device of claim 6, wherein the magnetic shield is adhesively attached to the PCB.

8. The device of claim 6, wherein the magnetic shield and coil are located on a first side of the PCB, and the battery is located on a second side of the PCB.

9. The device of claim 6, wherein the magnetic shield and battery are located on a first side of the PCB, and the coil is located on a second side of the PCB.

10. The device of claim 1, wherein the magnetic shield comprises a plurality of plates.

11. The device of claim 10, wherein each of the plurality of plates is a ferrite plate, and wherein the plurality of plates are configured in a tiled arrangement that substantially covers the entire extent of the coil.

12. An external device for use with an implantable medical device, comprising:

a housing;

a coil within the housing;

a battery within the housing; and

a magnetic shield within the housing made of a high permeability material, wherein the magnetic shield covers the battery,

wherein the magnetic shield and battery are within the extent of the coil, and

wherein the coil generates a magnetic field to provide power to the implantable medical device.

13. The device of claim 12, wherein the magnetic shield comprises a box.

14. The device of claim 13, wherein the box comprises two clamshell ferrite plates.

15. The device of claim 13, wherein the box comprises a plurality of ferrite plates configured in a tiled arrangement that substantially covers the entire battery.

16. The device of claim 12, further comprising a printed circuit board (PCB) within the housing of the external device.

17. The device of claim 16, wherein the PCB has a cutout area to accommodate the battery and magnetic shield.

18. The device of claim 16, further comprising electronic circuitry, wherein the coil is located around an outer edge of a first side of the PCB, and the electronic circuitry is located on a second side of the PCB.

19. The device of claim 12, wherein the magnetic shield contains gaps.

20. The device of claim 12, wherein the coil, battery, and magnetic shield are co-axially aligned.