ENHANCED MAGNETIC FIELD COMMUNICATION SYSTEM

• US 20080165074A1
• Filed: 03/19/2008
• Published: 07/10/2008
• Est. Priority Date: 11/25/2003
• Status: Active Grant

• Current Assignee: Starkey Laboratories Incorporated
• Original Assignee: Starkey Laboratories Incorporated
• Inventors: Terry, John David
• Granted Patent: US 7,710,345 B2
• Time in Patent Office: Days
• US Class Current: 343/842
• CPC Class Codes: G06K 19/0723 the record carrier comprising an arrangement for non-contact communication, e.g. wireless communication circuits on transponder cards, non-contact smart cards or RFIDs
• CPC Class Codes: G06K 19/07749 the record carrier being capable of non-contact communication, e.g. constructional details of the antenna of a non-contact smart card
• CPC Class Codes: H04B 5/0012 using capacitive coupling
• CPC Class Codes: H04B 5/0081 with antenna coils loop aerials H01Q7/00
• CPC Class Codes: H04B 5/02 using transceiver
• CPC Class Codes: H04B 5/22 Capacitive coupling
• CPC Class Codes: H04B 5/26 using coils
• CPC Class Codes: H04B 5/48 Transceivers

Abstract

Devices and methods are provided to enhance magnetic field communication. One aspect of the present subject matter relates to a method for transmitting and receiving signals using an antenna element electrically connected to a driver and an amplifier. According to various embodiments of the method, a first signal is transmitted from the antenna element and a second signal that was induced in the antenna element is received. Transmitting the first signal includes driving the first signal through the antenna element using the driver, and monitoring the first signal through an input impedance of the amplifier. Receiving the second signal includes reducing the input impedance of the amplifier, and receiving the second signal at the amplifier through the reduced input impedance. Various embodiments shield the antenna element from electric and electromagnetic fields. Other aspects are provided herein.

Claims

1. A method, comprising:

receiving a first signal induced in an antenna element, comprising;

shielding the antenna element from electric fields; and

controlling an input impedance switch to provide a differential amplifier with a first input impedance; and

transmitting a second signal, including;

controlling the input impedance switch to provide the differential amplifier with second input impedance larger than the first input impedance; and

driving the first signal through the antenna element.

2. The method of claim 1, wherein shielding the antenna element from electric fields includes:

distributing electrostatic charge across an electric field shield that extends along a length of the antenna element to provide a common mode voltage at a first terminal and a second terminal of the antenna element; and

rejecting the common mode voltage using the differential amplifier.

3. The method of claim 1, wherein shielding the antenna element from electric fields further comprises removing the electrostatic charge from the electric field shield using a reference potential.

4. The method of claim 1, wherein shielding the antenna element from electric fields includes shielding the antenna element using an electrostatic conductor surrounding a coil of the antenna element.

5. The method of claim 1, wherein shielding the antenna element from electric fields includes shielding the antenna element using an electrostatic conductor strip extending a length of the antenna element.

6. The method of claim 1, wherein controlling the input impedance switch includes selectively removing at least one element from an input impedance network for the differential amplifier.

7. The method of claim 6, wherein selectively removing the at least one element from the input impedance network for the differential amplifier includes shorting a series impedance to reduce the input impedance to the first input impedance, and removing a short from the series impedance to increase the input impedance to the second input impedance.

8. The method of claim 6, wherein selectively removing the at least one element from the input impedance network for the differential amplifier includes shorting a parallel impedance to increase the input impedance to the second input impedance, and removing a short from the parallel impedance to decrease the input impedance to the first input impedance.

9. The method of claim 1, further comprising monitoring a transmission of the second signal using the differential amplifier and the second input impedance.

10. The method of claim 1, wherein:

transmitting the second signal includes enabling a driver to drive the second signal through the antenna element; and

receiving the first signal includes disabling the driver.

11. The method of claim 1, further comprising:

monitoring an RF input to detect an RF carrier signal;

transmitting the second signal in response to a detected RF carrier signal; and

receiving the first signal when an RF carrier signal is not detected.

12. A method, comprising:

monitoring an RF input to detect an RF carrier signal;

receiving a first signal induced in an antenna element when an RF carrier signal is not detected, comprising;

shielding the antenna element from electric fields; and

controlling an input impedance switch to provide a differential amplifier with a first input impedance; and

transmitting a second signal in response to a detected RF carrier signal, including;

controlling the input impedance switch to provide the differential amplifier with second input impedance larger than the first input impedance; and

driving the first signal through the antenna element,

wherein controlling the input impedance switch includes selectively removing at least one element from an input impedance network for the differential amplifier.

13. The method of claim 12, wherein shielding the antenna element from electric fields includes:

distributing electrostatic charge across an electric field shield that extends along a length of the antenna element to provide a common mode voltage at a first terminal and a second terminal of the antenna element; and

rejecting the common mode voltage using the differential amplifier.

14. The method of claim 12, wherein shielding the antenna element from electric fields further comprises removing the electrostatic charge from the electric field shield using a reference potential.

15. The method of claim 12, wherein controlling the input impedance switch includes selectively removing at least one element from an input impedance network for the differential amplifier.

16. The method of claim 12, wherein selectively removing the at least one element from the input impedance network for the differential amplifier includes shorting a series impedance to reduce the input impedance to the first input impedance, and removing a short from the series impedance to increase the input impedance to the second input impedance.

17. The method of claim 12, wherein selectively removing the at least one element from the input impedance network for the differential amplifier includes shorting a parallel impedance to increase the input impedance to the second input impedance, and removing a short from the parallel impedance to decrease the input impedance to the first input impedance.

18. A method, comprising:

receiving a first signal induced in an antenna element, comprising;

shielding the antenna element from electric fields using an electrostatic conductor surrounding a coil of the antenna element or an electrostatic conductor strip extending a length of the antenna element; and

controlling an input impedance switch to provide a differential amplifier with a first input impedance;

transmitting a second signal, including;

controlling the input impedance switch to provide the differential amplifier with second input impedance larger than the first input impedance; and

driving the first signal through the antenna element; and

monitoring a transmission of the second signal using the differential amplifier and the second input impedance.

19. The method of claim 18, wherein shielding the antenna element from electric fields further comprises removing the electrostatic charge from the electric field shield using a reference potential.

20. The method of claim 18, wherein shielding the antenna element from electric fields includes shielding the antenna element using an electrostatic conductor surrounding a coil of the antenna element.