Immobilizer circuit

• US 8,816,835 B2
• Filed: 07/22/2013
• Issued: 08/26/2014
• Est. Priority Date: 11/01/2010
• Status: Active Grant

• Current Assignee: NXP B.V. (NXP Semiconductors NV)
• Original Assignee: NXP B.V. (NXP Semiconductors NV)
• Inventors: Kofler, Robert
• Primary Examiner(s): Previl, Daniel
• Application Number:
  US13/947,482
• Publication Number:
  US 20130309970A1
• Time in Patent Office: 400 Days
• Field of Search: 340/426.16, 340/426.13, 340/426.14, 340/426.28, 340/426.3, 340435-439, 340463-464
• US Class Current: 340/426.16
• CPC Class Codes: H04B 5/24 Inductive coupling
• CPC Class Codes: H04B 5/45 Transponders
• CPC Class Codes: H04B 5/48 Transceivers
• CPC Class Codes: H04B 5/77 for interrogation

Abstract

An immobilizer device is configured for communicating with a base station. The immobilizer device includes an antenna circuit including three orthogonally-oriented antennas configured to receive a signal from a field generated by a base station. A power circuit is configured to draw power via the field on each of the antennas, and a communications circuit is configured to communicate with the base station via any of the antennas. The strength of the signals received via the antennas is evaluated and used to select one of the antennas for use in data communications and, if appropriate, as a power supply.

Claims

1. An immobilizer device for communicating with a base station, the immobilizer device comprising:

an RF antenna circuit including three antennas orthogonally-oriented relative to one another, each said antenna being configured to receive wireless transmissions from the base station, the RF antenna circuit having for each antenna an associated antenna channel carrying signals received by that said each antenna;

a wireless power circuit connected to the RF antenna circuit and configured to generate power using signals received from the base station via at least one of the three antennas;

a communications circuit connected to the antenna circuit and configured to

select one of the antenna channels exhibiting a signal strength that is higher than that of the other said antenna channels, and

supply signals from the selected antenna channel to the wireless power circuit, the wireless power circuit employing the supplied signals to generate power; and

a logic circuit configured to process data communications on at least one of the antenna channels, and to generate a data communication for transmission to the base station using the communications circuit and at least one of the antennas;

wherein the communications circuit and the logic circuit operate using the power generated by the wireless power circuit.

2. The immobilizer device according to claim 1, wherein the data communication for transmission to the base station takes place via the selected antenna channel.

3. The immobilizer device according to claim 1, wherein each said antenna is a coil antenna.

4. The immobilizer device according to claim 1, further comprising:

a battery,

wherein the communications circuit and the logic circuit only use the power generated by the wireless power circuit when a power of the battery is not available.

5. The immobilizer device according to claim 1, wherein each said antenna operates at a frequency between about 20 kHz and 150 kHz.

6. The immobilizer device according to claim 1, wherein the communications circuit includes a demodulator configured to evaluate the signal strength of each antenna channel and select the antenna channel with the highest signal strength.

7. An immobilizer device for communicating with a base station, the immobilizer device comprising:

an RF antenna circuit including three antennas orthogonally-oriented relative to one another, each said antenna being configured to receive wireless transmissions from the base station, the antenna circuit having for each antenna an associated antenna channel carrying signals received by that said antenna;

a wireless power circuit connected to the antenna circuit and configured to generate power using signals received from the base station via at least one of the three antennas;

a communications circuit connected to the antenna circuit and configured to

select two of the antenna channels exhibiting signal strengths that are higher than that of a remaining said antenna channel, and

supply signals from the selected antenna channels to the wireless power circuit, the wireless power circuit employing the supplied signals to generate power; and

a logic circuit configured to process data communications on at least one of the antenna channels, and to generate a data communication for transmission to the base station using the communications circuit and at least one of the antennas;

wherein the communications circuit and the logic circuit operate using the power generated by the wireless power circuit.

8. The immobilizer device according to claim 7, wherein the data communication for transmission to the base station takes place via one of the selected antenna channels.

9. The immobilizer device according to claim 7, wherein each said antenna is a coil antenna.

10. The immobilizer device according to claim 7, further comprising:

a battery,

wherein the communications circuit and the logic circuit only use the power generated by the wireless power circuit when a power of the battery is not available.

11. The immobilizer device according to claim 7, wherein each said antenna operates at a frequency between about 20 kHz and 150 kHz.

12. The immobilizer device according to claim 7, wherein the communications circuit includes a demodulator configured to evaluate the signal strength of each antenna channel and select the two antenna channels with the signal strengths that are higher than that of the remaining said antenna channel.

13. A method for communication between an immobilizer device and a base station, the method comprising:

at the immobilizer device, receiving wireless transmissions from the base station using an RF antenna circuit having three antennas orthogonally-oriented relative to one another;

generating, at the immobilizer device, signals corresponding to the received wireless transmissions on each of the three antennas, and providing, respectively, each generated signal on a channel corresponding to the each antenna of the three antennas;

selecting, at the immobilizer device, one of the channels exhibiting a signal strength that is higher than that of the other said channels;

generating, at the immobilizer device, power from the selected channel; and

using, at the immobilizer device, the generated power to process an incoming data communication on at least one of the antenna channels, and to generate and transmit an outgoing data communication to the base station using at least one of the antennas.

14. The method according to claim 13, further comprising:

selecting, at the immobilizer device, one of the channels having an intermediate signal strength,

wherein the generating of power uses the channel with the signal strength that is higher than that of the other said channels and the channel having the intermediate signal strength.

15. The method according to claim 13, wherein the outgoing data communication takes place via the selected antenna channel.

16. The method according to claim 13, wherein each said antenna is a coil antenna.

17. The method according to claim 13, further comprising:

providing a battery,

wherein the using of the power generated by the wireless power circuit only occurs when a power of the battery is not available.

18. The method according to claim 13, wherein each said antenna operates at a frequency between about 20 kHz and 150 kHz.