Method and system for a headset H-field/E-field canceller

• US 8,218,801 B2
• Filed: 05/30/2008
• Issued: 07/10/2012
• Est. Priority Date: 05/30/2008
• Status: Active Grant

• Current Assignee: Symbol Technologies, LLC (Zebra Technologies Corporation)
• Original Assignee: Symbol Technologies, Inc. (Zebra Technologies Corporation)
• Inventors: Duron, Mark, Knadle, Richard
• Primary Examiner(s): Warren, David S.
• Application Number:
  US12/130,361
• Publication Number:
  US 20090296947A1
• Time in Patent Office: 1,502 Days
• Field of Search: 381/71.3, 381/71.6, 381/71.7, 381/71.8, 381/94.6, 381/317, 381/318, 381/312, 381/322, 381/326, 381/331
• US Class Current: 381/317
• CPC Class Codes: H04R 2225/49 Reducing the effects of electromagnetic noise on the functioning of hearing aids, by, e.g. shielding, signal processing adaptation, selective (de)activation of electronic parts in hearing aid
• CPC Class Codes: H04R 25/554 using a wireless connection, e.g. between microphone and amplifier or using Tcoils

Abstract

Described are a device and a method for canceling a magnetic field and/or an electric field emitted from a device. The device includes a housing including an inner wall and an outer wall, a sense coil located within the inner wall of the housing in proximity to a user'"'"'s ear, the sense coil sensing a magnitude, polarization and a polarity of an inbound magnetic field within the housing, and an induction coil located between the outer wall and the inner wall of the housing, the induction coil generating an outbound magnetic field having the same polarization and an opposing polarity to the polarity of the inbound magnetic field. The method includes sensing, by a sensing coil, a magnitude and a polarity of an inbound magnetic field, the sensing coil located within a housing of a device, and applying a current to an induction coil to generate an outbound magnetic field having an opposing polarity to the polarity of the inbound magnetic field, the induction coil located within the housing of the device.

Claims

1. A device for reducing interference for a hearing aid device, comprising:

a housing including an inner wall and an outer wall, at least one of the inner and outer wall provides partial electromagnetic shielding;

a sense coil located within the inner wall of the housing in proximity to the hearing aid device, the sense coil operable for sensing a magnitude, polarization and a polarity of an inbound interfering magnetic field within the housing; and

an induction coil located between the outer wall and the inner wall of the housing, the induction coil operable for generating an outbound magnetic field having the same polarization and an opposing polarity to the polarity of the inbound interfering magnetic field, wherein the outbound magnetic field is of a magnitude substantially equal to the magnitude of the inbound interfering magnetic field such that the induction coil substantially nullifies the interfering magnetic field within the hearing aid device.

2. The device of claim 1, wherein the sense coil is further configured to sense an inbound interfering electric field, and further comprising an electrostatic probe operable for generating an outbound electric field to nullify the inbound interfering electric field within the hearing aid device.

3. The device of claim 1, wherein the induction coil is configured with up to three orthogonally-oriented coils to cancel cancels at least one of a magnetic field component in each of up to three orthogonal directions.

4. The device of claim 1,

wherein the induction coil is also operable as a pick-up coil external to the hearing aid and operable for picking up an intended magnetic field and relaying the intended magnetic field to a telecoil of the hearing aid device via the sense coil.

5. The device of claim 4, further comprising:

an external audio pick-up configured to convert audio signals to electric signals to drive the induction coil to relay the signals to the telecoil.

6. The device of claim 1, wherein the outbound magnetic field from the induction coil is also operable to nullify the interfering magnetic field within the sense coil.

7. The device of claim 1, wherein the magnetic sense coil can include a singly-polarized element.

8. The device of claim 1, wherein the magnetic sense coil can include a dual orthogonal cross-polarized array.

9. The device of claim 1, wherein the magnetic sense coil can include a triple orthogonal cross-polarized array.

10. The device of claim 1, further comprising an electric sense probe wherein the sense probe can include dual orthogonal elements.

11. The device of claim 1, further comprising an electric sense probe wherein the sense probe can include triple orthogonal elements.

12. The device of claim 1, wherein pre-distortion is applied for the outbound magnetic field at the induction coil to correct displacement error of the nullification at the hearing aid device.

13. A method for reducing interference for a hearing aid device, comprising:

sensing, by a sensing coil, a polarization, magnitude and a polarity of an inbound interfering magnetic field, the sensing coil located within a housing of a device and disposed within a wall providing partial electromagnetic shielding, the sensing coil located in proximity to the hearing aid device; and

applying a current to an induction coil disposed outside of the wall to generate an outbound electromagnetic field having the same polarization and an opposing polarity to the polarity of the inbound interfering magnetic field, the induction coil located within the housing of the device and disposed outside a wall providing partial electromagnetic shielding, wherein the outbound magnetic field is of a magnitude substantially equal to the magnitude of the inbound interfering magnetic field such that the induction coil substantially nullifies the interfering magnetic field within the hearing aid device.