Nearfield inductive coupling in a contact hearing system
In one embodiment, the present invention is directed to a method of transmitting information from an ear tip to a contact hearing device, the method comprising the steps of: exciting a transmit coil, the transmit coil being positioned in the ear tip, wherein the transmit coil is wound on a core, the core including a ferromagnetic material; radiating an electromagnetic field from the first coil through the ear canal of a user; receiving the radiated electromagnetic field at a receive coil, the receive coil being positioned on a contact hearing device, the contact hearing device including a receive coil without a ferrite core; and transmitting the information from the transmit coil to the receive coil using, for example, near-field radiation.
1. A method of transmitting audio information from an ear tip to a contact hearing device, the method comprising the steps of:
exciting a transmit coil using a varying current, the transmit coil being positioned in the ear tip, wherein the transmit coil is wound on a core, the core comprising a ferromagnetic material;
radiating an electromagnetic field from the transmit coil through an ear canal of a user, wherein the radiated electromagnetic field is amplitude modulated based on the varying current of the transmit coil to be indicative of audio information;
receiving the radiated electromagnetic field at a receive coil positioned on a contact hearing device wherein the receive coil has a core which is not ferromagnetic; and
transmitting audio information and power from the transmit coil to the receive coil using near-field radiation, wherein the near-field radiation induces an amplitude modulated signal at the receive coil indicative of the audio information and providing power to drive a microactuator that transduces the amplitude modulated signal using the audio information.
2. A method according to claim 1 , wherein the ear tip comprises the transmit coil and the contact hearing device comprises the receive coil, the method comprising the step of adapting the ear tip such that it positions a medial end of the transmit coil to be within between 3 and 7 millimeters of a lateral end of the receive coil when the ear tip and contact hearing device are positioned in the ear canal.
3. A method according to claim 1 , wherein the ear tip comprises the transmit coil and the contact hearing device comprises the receive coil, the method comprising the step of adapting the ear tip such that when it is positioned in the ear canal of a user more than fifty percent of magnetic flux lines emanating from the transmit coil couple through the receive coil.
4. A method according to claim 1 , wherein the ear tip comprises the transmit coil and the contact hearing device comprises the receive coil, the method comprising the step of adapting the ear tip such that when it is positioned in the ear canal of a user more than seventy five percent of a magnetic field generated by the transmit coil is coupled to the receive coil.
5. A method according to claim 1 , wherein the step of exciting the transmit coil induces current in the receive coil, wherein the induced current is induced by the presence of a magnetic field generated at the transmit coil.
6. A method according to claim 5 , wherein the current induced is proportional to the magnetic field at the transmit coil.
7. A method according to claim 1 , wherein the step of exciting the transmit coil results in a voltage generated across the receive coil wherein the generated voltage is a product of the magnetic field generated at the transmit coil.
8. A method according to claim 7 , wherein the voltage generated is proportional to the magnetic field at the transmit coil.
9. A method according to claim 1 , wherein the transmitted audio information is transmitted in an amplitude modulated (AM) signal.
10. A method according to claim 1 , wherein the transmitted audio information is demodulated by a demodulator attached to a receive coil.
11. A method according to claim 1 , wherein the transmit coil is magnetically coupled to the receive coil.
12. A method according to claim 11 , wherein coupling between the transmit and receive coils is between approximately 0.1 percent and approximately 3.0 percent.
13. A method according to claim 1 , wherein the audio information and the power are transmitted from the transmit coil to the receive coil through the interaction of magnetic fields generated in the transmit coil with the receive coil.
14. A method according to claim 1 , wherein the core comprises a ferrite material.
15. A method of transmitting audio information from an ear tip to a contact hearing device, the method comprising the steps of:
exciting a transmit coil using a varying current, the transmit coil being positioned in an ear tip, wherein the transmit coil is wound on a ferromagnetic core;
radiating an electromagnetic field from the transmit coil through an ear canal of a user, wherein the radiated electromagnetic field is amplitude modulated based on the varying current of the transmit coil to be indicative of audio information;
receiving the radiated electromagnetic field at a receive coil positioned on a contact hearing device, the receive coil having a core of a non-ferromagnetic material; and
transmitting audio information and power from the transmit coil to the receive coil using near-field radiation, wherein the near-field radiation induces an amplitude modulated signal at the receive coil indicative of the audio information and providing power to drive a microactuator that transduces the amplitude modulated signal using the audio information.
16. A method according to claim 15 , wherein the transmit and receive coils are inductively coupled.
17. A method according to claim 15 , wherein inductive coupling is used to link the transmit coil to the receive coil.
18. A method according to claim 15 , wherein the audio information is transmitted from the transmit coil to the receive coil using near-field magnetic coupling.
19. A method according to claim 15 , wherein the audio information is transmitted from the transmit coil to the receive coil using resonant inductive coupling.
20. A method according to claim 15 , wherein the audio information is transmitted from the transmit coil to the receive coil using near-field magnetic induction.
21. A method according to claim 15 , wherein the audio information is transmitted from the transmit coil to the receive coil using a near-field magnetic induction link.
22. A method according to claim 15 , wherein the output of the contact hearing device varies by less than two decibels sound pressure level (dB SPL) when the distance between the transmit and receive coils varies by between three and seven millimeters.
23. A method according to claim 15 , wherein the receive coil is a part of a receive coil assembly, the receive coil assembly comprising:
the receive coil; and
at least one disk positioned at a distal end of the receive coil, the at least one disk comprising a ferromagnetic material.
24. A method according to claim 23 , wherein the receive coil is wound with a central core of a non-ferromagnetic material.
25. A method according to claim 24 , wherein the non-ferromagnetic material is, at least in part, air.
26. A method according to claim 23 , wherein an outer diameter of the at least one disk is substantially the same as an outer diameter of the receive coil.
27. A method according to claim 26 , wherein the at least one disk includes a hole therethrough.
28. A method according to claim 23 , wherein the at least one disk is two disks.
29. A method according to claim 23 , wherein a printed circuit board including electronic components is affixed to a side of the at least one disk opposite a side to which the receive coil is affixed.
30. A method according to claim 29 , wherein the electronic components on the printed circuit board comprise a demodulation circuit.
31. A method according to claim 30 , wherein the demodulation circuit is a diode demodulator.
32. A method according to claim 23 , wherein the at least one disk comprises a ferrite material.