Bone conduction magnetic retention system

1. An external component of a medical device, comprising:

a transducer including a static magnetic flux circuit that interacts with a dynamic magnetic flux circuit; and

a magnetic retention system configured to retain the external component to a recipient via interaction with a ferromagnetic component attached to a recipient, the magnetic retention system including a magnetic flux circuit that encircles the static magnetic flux circuit of the transducer.

2. The external component of claim 1 , wherein:

the external component is configured to channel the magnetic flux circuit of the magnetic retention system around the transducer.

3. A passive transcutaneous bone conduction device, comprising:

the external component of claim 1 ; and

an implantable component including ferromagnetic material configured to be totally implanted underneath skin of the recipient and attached to bone of the recipient, wherein

the passive transcutaneous bone conduction device is configured such that the magnetic flux circuit of the magnetic retention system extends through skin of the recipient to the ferromagnetic material of the implantable component resulting in magnetic attraction between the external component and the implantable component, thereby removably retaining the external component to the recipient.

4. The passive transcutaneous bone conduction device of claim 3 , wherein:

the ferromagnetic material is a permanent magnet having a North-South pole axis, wherein the implantable component is configured such that the North-South pole axis is parallel to bone of the recipient when the implantable component is implanted and attached to bone of a recipient.

5. The external component of claim 1 , wherein:

substantially all of the magnetic flux of the magnetic retention system is separated from the static magnetic flux of the transducer.

6. The external component of claim 1 , wherein:

the transducer is an actuator;

the device is configured such that actuation of the actuator moves a seismic mass along a first direction normal to a surface of a skin of a recipient of the device;

the magnetic retention system includes at least one permanent magnet;

the actuator includes at least one permanent magnet; and

a plane normal to the first direction bisects the at least one permanent magnet of the actuator and the at least one permanent magnet of the magnetic retention system.

7. The external component of claim 1 , wherein:

the transducer includes permanent magnets that generate the static magnetic flux, which permanent magnets are not used to generate at least any substantial amount of the magnetic flux of the magnetic retention system.

8. The external component of claim 1 , wherein:

the external component includes a housing containing the transducer.

9. The external component of claim 1 , wherein:

the magnetic flux circuit that encircles the static magnetic flux circuit of the transducer is spaced away from the static magnetic flux circuit of the transducer and is generated entirely by magnets that remain static upon transduction by the transducer.

10. A percutaneous bone conduction device, comprising:

the external component of claim 1 ; and

a percutaneous implant including ferromagnetic material configured to be connected to bone of a recipient and to extend through skin of the recipient, wherein

the transducer is an actuator, and

the percutaneous bone conduction device is configured such that the magnetic flux circuit of the magnetic retention system extends to the ferromagnetic material of the percutaneous implant resulting in magnetic attraction between the external component and the percutaneous implant, thereby removably retaining the external component to the recipient.

11. An external component of a bone conduction system, comprising:

an actuator; and

a permanent magnet separate from the actuator, wherein

the permanent magnet generates a permanent magnetic field having substantial components located outside the actuator on substantially opposite sides of the actuator for removably attaching the external component to a recipient via interaction of the permanent magnetic field with ferromagnetic material of an implanted component.

12. The external component of claim 11 , further comprising:

a plurality of permanent magnets, the plurality of permanent magnets including the permanent magnet separate from the actuator, wherein

a first of the permanent magnets has a North-South pole axis in a first direction,

a second of the permanent magnets has a North-South pole axis in a second direction at least substantially opposite the first direction, and

the permanent magnetic field is generated by both the first magnet and the second magnet.

13. The external component of claim 11 , wherein:

the permanent magnetic field encircles the actuator.

14. The external component of claim 11 , wherein:

the actuator is an electromagnetic actuator configured to generate a dynamic magnetic flux; and

the external component is configured such that the generated dynamic magnetic flux is effectively isolated from interaction with the permanent magnetic field.

15. The external component of claim 11 , wherein:

the external component includes a first surface configured to contact skin of the recipient through which vibrations generated by the actuator are conducted into skin of the recipient; and

a height of the external component as dimensioned from the first surface is no more than about fifteen millimeters.

16. A bone conduction device, comprising:

the external component of claim 11 ; and

an implantable component including ferromagnetic material, wherein

the permanent magnetic field travels a circuit that passes through the permanent magnet and the ferromagnetic material of the implantable component and encircles the actuator, thereby removably attaching the external component to the recipient.

17. A removable component of a bone conduction system, comprising:

a recipient interface component;

an actuator coupled to the recipient interface component, the actuator including a seismic mass, wherein actuation of the actuator moves the seismic mass relative to the recipient interface component;

a plurality of retention magnets separate from the seismic mass; and

a housing,

wherein the actuator is in the housing, and the plurality of retention magnets are at about a same height as the actuator.

18. The removable component of claim 17 , wherein:

the actuator is located between the retention magnets.

19. The removable component of claim 17 , wherein:

a magnitude of movement of the seismic mass is greater than that of any movement of the retention magnets relative to the recipient interface component, wherein the retention magnets are supported by components of the removable component other than the recipient interface component.

20. The removable component of claim 17 , further comprising:

a ferromagnetic component extending from a first lateral location of the removable component proximate a first of the retention magnets to a second lateral location of the removable component proximate a second of the retention magnets, wherein

the plurality of retention magnets generate a magnetic field having a circuit that extends:

the first of the retention magnets to the ferromagnetic component;

through the ferromagnetic component;

from the ferromagnetic component to the second of the retention magnets; and

from the second of the retention magnets out of the removable component beyond the recipient interface component and then back into the removable component and then to the first retention magnet.

21. The removable component of claim 20 , wherein:

the circuit is magnetically isolated from electronic circuitry of the removable component, the circuitry being located between the first magnet and the second magnet.

22. The removable component of claim 17 , wherein:

the plurality of retention magnets generate a magnetic field having a single retention circuit.

23. The removable component of claim 17 , wherein:

the plurality of retention magnets generate a magnetic field having a circuit that retains the removable component to the recipient; and

the actuator is an electromagnetic actuator having a static magnetic field circuit that interacts with a dynamic magnetic field circuit to actuate the actuator, wherein the static magnetic field circuit and the circuit that retains the removable component to the recipient have completely separate paths.

24. The removable component of claim 17 , wherein:

the actuator includes a plurality of permanent magnets that generate a static magnetic field that interacts with a dynamic magnetic field of the actuator; and

the plurality of permanent magnets move relative to the plurality of retention magnets when the actuator is actuated; and

the plurality of retention magnets are spaced away from the recipient interface component and proximate the actuator.

25. The removable component of claim 17 , wherein:

the recipient interface component is devoid of any magnets.

26. The removable component of claim 17 , wherein:

the housing supports the plurality of retention magnets.