Methods and apparatus for tuning in an inductive system

• US 20050130601A1
• Filed: 11/01/2004
• Published: 06/16/2005
• Est. Priority Date: 03/16/2001
• Status: Active Grant

• Current Assignee: Freelinc Holdings, LLC
• Original Assignee: Aura Communications Technology, Inc. (Radeum, Inc.)
• Inventors: Terranova, Domenic F., Palermo, Vincent
• Granted Patent: US 7,035,608 B2
• Time in Patent Office: Days
• US Class Current: 455/73
• CPC Class Codes: G06K 7/0008 General problems related to the reading of electronic memory record carriers, independent of its reading method, e.g. power transfer
• CPC Class Codes: H03J 1/0008 using a central processing unit, e.g. a microprocessor digital tuning in general H03J5/0245
• CPC Class Codes: H03J 5/0245 Discontinuous tuning using an electrical variable impedance element, e.g. a voltage variable reactive diode, in which no corresponding analogue value either exists or is preset, i.e. the tuning information is only available in a digital form microprocessor tuning H03J1/0008
• CPC Class Codes: H04B 5/00 Near-field transmission systems, e.g. inductive or capacitive transmission systems
• CPC Class Codes: H04B 5/22 Capacitive coupling
• CPC Class Codes: H04B 5/48 Transceivers
• CPC Class Codes: H04M 1/6066 including a wireless connection
• CPC Class Codes: H04R 2420/07 Applications of wireless loudspeakers or wireless microphones

Abstract

Electronic circuitry supports utilization of a series of pulses of varying width to tune a transducer (e.g., a coil that produces or receives a magnetic field) for transmitting or receiving. For example, a control voltage generator generates a sequence of digital pulses of varying pulse widths to produce respective control voltages. The control voltage generator applies a produced control voltage to a varactor element whose capacitance changes depending on a magnitude of the produced control voltage. The varactor element forms part of a tank circuit. Consequently, the series of pulse widths controls an operating frequency of the tank circuit at different times. The tank circuit includes an inductive coil that is tuned to produce or receive a magnetic or inductive field.

Claims

1. A method of electronically tuning a transducer assembly for at least one of transmission and reception of inductive signals, the method comprising:

identifying a desired operating frequency to tune the transducer assembly;

generating a pulse in a control signal for a duration of time to tune the transducer assembly to the desired operating frequency; and

utilizing the tuned transducer assembly for at least one of transmission and reception of inductive signals.

2. A method as in claim 1 further comprising:

selecting a given transducer circuit of multiple transducer circuits in the transducer assembly for tuning, the given transducer circuit including a respective transducer on which to receive and transmit the inductive signals; and

tuning the given transducer circuit to the desired operating frequency based on generation of the pulse in the control signal.

3. A method as in claim 2, wherein tuning the given transducer includes:

utilizing the pulse in the control signal to generate a control voltage; and

applying the control voltage to a circuit component of the given transducer circuit to tune the respective transducer to the desired operating frequency, wherein an impedance of the circuit component and tuning of the given transducer circuit changes depending on a magnitude of the applied control voltage.

4. A method as in claim 1 further comprising:

tuning a transducer in the transducer assembly to transmit an inductive signal at a first carrier frequency based on generating a first duration of the pulse in the control signal;

following transmission of the inductive signal from the transducer on the first carrier frequency, re-tuning the transducer in the transducer assembly to receive an inductive signal on a second carrier frequency based on generating a second duration of the pulse in the control signal.

5. A method as in claim 4, wherein generating the pulse in the control signal produces a control voltage that tunes the transducer assembly, the control voltage being larger for longer durations of pulses present in the control signal, the method further comprising:

substantially resetting the control voltage to zero prior to re-tuning the transducer to receive the inductive signal on the second carrier frequency.

6. A method as in claim 1, wherein a magnitude of the control voltage is greater than a voltage magnitude of the pulse in the control signal.

7. A method as in claim 1 further comprising:

tuning a transducer in the transducer assembly to transmit an inductive signal at a first carrier frequency based on generating a first duration of the pulse in the control signal;

following transmission of the inductive signal from the transducer on the first carrier frequency, re-tuning the transducer in the transducer assembly to transmit an inductive signal on a second carrier frequency based on generating a second duration of the pulse in the control signal.

8. A method as in claim 1 further comprising:

applying a control voltage, which is produced as a result of generating the pulse in the control signal, to tune at least one of multiple transducer circuits of the transducer assembly, each of the transducer circuits including at least one respective transducer to transmit and receive inductive signals.

9. A method as in claim 8 further comprising:

activating a single tuned transducer circuit in the transducer assembly for at least one of transmission and reception of inductive signals.

10. A method as in claim 1 further comprising:

storing calibration information including different pulse durations for tuning a transducer circuit in the transducer assembly to different operating frequencies; and

utilizing the calibration information to identify a pulse duration in the control signal required to tune the transducer assembly to the desired operating frequency.

11. A method as in claim 1 further comprising:

generating the calibration information based on tuning the transducer assembly and identifying a respective operating frequency for each of different pulse durations in the control signal.

12. A method as in claim 1 further comprising:

in the transducer assembly, providing a transducer tank circuit whose parasitic impedances change depending on whether the transducer assembly is set to a transmit mode versus a receive mode, the transducer tank circuit including a respective inductive element for at least one of transmission and reception of inductive signals.

13. A method as in claim 12 further comprising:

utilizing a pulse in the control signal to produce a control voltage and tune the transducer tank circuit; and

utilizing a reset signal to reset the control voltage prior to later re-tuning the transducer tank circuit to a different operating frequency based on generating another duration of a pulse in the control signal.

14. An apparatus comprising:

a transducer assembly supporting at least one of transmission and reception of inductive signals;

a control circuit that selects a desired operating frequency to tune the transducer assembly; and

a pulse generator circuit controlled by the control circuit, the pulse generator circuit generating pulses in a control signal to tune the transducer assembly to the desired operating frequency.

15. An apparatus as in claim 14, wherein the transducer assembly includes multiple transducer circuits, the control circuit further supporting operations of:

selecting a given transducer circuit of multiple transducer circuits in the transducer assembly for tuning, the given transducer circuit including a respective transducer element on which to at least one of receive and transmit the inductive signals; and

tuning the given transducer circuit to the desired operating frequency based on initiating the pulse generator circuit to generate a pulse in the control signal.

16. An apparatus as in claim 15 further comprising:

a control voltage circuit that receives a pulse from the pulse generator circuit and generates a control voltage, the control voltage circuit applying the control voltage to a capacitive circuit component of the given transducer circuit to tune the respective transducer in the transducer assembly to the desired operating frequency, wherein an impedance of the capacitive circuit component and tuning of the given transducer circuit changes depending on a magnitude of the control voltage generated by the control voltage circuit.

17. An apparatus as in claim 16, wherein the capacitive circuit component is a varactor device whose impedance varies depending on a magnitude of the control voltage.

18. An apparatus as in claim 14, wherein the control circuit tunes a transducer in the transducer assembly to transmit an inductive signal at a first carrier frequency based on initiation of the pulse generator circuit to generate a first duration of a pulse in the control signal, and following transmission of an inductive signal from the transducer on the first carrier frequency, the control circuit re-tuning the transducer in the transducer assembly to receive an inductive signal on a second carrier frequency based on initiation of the pulse generator circuit to generate a second duration of a pulse in the control signal.

19. An apparatus as in claim 18, wherein generation of a pulse by the pulse generator causes a control voltage generator to produce a control voltage that tunes the transducer assembly, the control voltage generator producing larger control voltages for a longer pulse width received from the pulse generator circuit;

and

the control circuit substantially resetting the control voltage to zero prior to re-tuning the transducer to receive the inductive signal on the second carrier frequency.

20. An apparatus as in claim 14 further comprising:

a control voltage generator that applies a control voltage, which is produced as a result of a presence of a pulse in the control signal, to tune at least one of multiple transducer circuits of the transducer assembly, each of the transducer circuits in the transducer assembly including at least one respective transducer to transmit and receive inductive signals.

21. An apparatus as in claim 20, wherein the control circuit activates a single tuned transducer circuit in the transducer assembly for at least one of transmission and reception of inductive signals.

22. An apparatus as in claim 14, wherein the control circuit includes associated memory to store calibration information including different pulse widths for tuning a transducer circuit in the transducer assembly to different operating frequencies, the control circuit accessing the calibration information in memory to identify the duration of pulses required to tune the transducer assembly to the desired operating frequencies.

23. An apparatus as in claim 14, wherein the control circuit maintains calibration information based on:

i) tuning the transducer assembly based on application of pulses of different pulse widths, and ii) identifying respective operating frequencies of a transducer circuit in the transducer assembly for the different pulse widths.

24. An apparatus as in claim 14, wherein the transducer assembly includes a tank circuit whose parasitic impedances change depending on whether the transducer assembly is set to a transmit mode versus a receive mode, the tank circuit including a respective inductive element supporting at least one of transmission and reception of inductive signals.

25. An apparatus as in claim 24, wherein the control circuit initiates generation of pulse width in the control signal to produce a control voltage and tune the transducer tank circuit, the control circuit further initiating generation of a reset signal to reset the control voltage prior to later re-tuning the transducer tank circuit to a different operating frequency based on initiating generation of another duration of a pulse.

26. An apparatus as in claim 14 further comprising:

a control voltage generator circuit that generates a control voltage depending on a pulse received from the pulse generator circuit, a magnitude of the control voltage generated by the a control voltage generator circuit being greater than a voltage magnitude of the pulse received from the pulse generator circuit.

27. An apparatus as in claim 26, wherein the voltage magnitude of the pulse generated by the pulse generator circuit is less than 4 volts and the magnitude of the control voltage is greater than 6 volts.

29. A method as in claim 27, wherein the control signal tunes a tank circuit including the specific transducer of the transducer assembly, the specific transducer being an inductive element to at least one of transmit and receive inductive signals at the desired operating frequency.

28. A method of electronically tuning a transducer assembly for at least one of transmission and reception of inductive signals, the method comprising:

identifying a desired operating frequency and a specific transducer to tune in the transducer assembly;

initiating generation of a pulse in a control signal to tune the specific transducer in the transducer assembly to the desired operating frequency; and

utilizing the specific transducer in the transducer assembly for at least one of transmission and reception of inductive signals at the desired operating frequency.

30. A method of supporting inductive communications, the method comprising steps of:

coupling one of multiple transducers to a circuit to transmit or receive a magnetic field;

selecting a frequency for communicating via the magnetic field;

via use of a varactor device, sweeping through a range of impedance values to identify which of multiple values is optimal for transmitting or receiving over the coupled one of multiple transducers at the selected frequency; and

storing an identified optimal impedance value for later use.