Contactless integrated circuit reader

• US 20030169152A1
• Filed: 04/10/2003
• Published: 09/11/2003
• Est. Priority Date: 10/16/2000
• Status: Active Grant

• Current Assignee: Verimatrix Incorporated (Verimatrix SA)
• Original Assignee: Inside Technologies (Verimatrix SA)
• Inventors: Charrat, Bruno, Lepron, Francois
• Granted Patent: US 7,098,770 B2
• Time in Patent Office: Days
• US Class Current: 340/10.1
• 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

Abstract

The present invention relates to a contactless integrated circuit reader operating by inductive coupling, comprising an antenna circuit for sending an alternating magnetic field, circuits for applying an alternating excitation signal to the antenna circuit and circuits for modulating the amplitude of an antenna signal present in the antenna circuit according to data to be sent. The reader includes circuits for simulating the operation of a contactless integrated circuit, arranged to inhibit the application of the excitation signal to the antenna circuit and to apply a load modulation signal to the antenna circuit when data is to be sent. The load modulation signal is capable of disturbing a magnetic field sent by another contactless integrated circuit reader and of being detected by the other contactless integrated circuit reader.

Claims

1. Inductive coupling data send-receive device having an antenna circuit and means for delivering an alternating excitation signal for exciting the antenna circuit, the send-receive device comprising:

means for simulating the operation of a contactless integrated circuit, the send-receive device configured to apply a load modulation signal with two states to the antenna circuit when data is to be sent, said load modulation signal being capable of disturbing a magnetic field sent by a contactless integrated circuit reader and of being detected by said contactless integrated circuit reader as if said load modulation signal were a load modulation signal applied to an antenna short-circuiting switch of a contactless integrated circuit.

2. Device according to claim 1, wherein the load modulation signal comprises pulses of the excitation signal, the duration of each pulse being longer than the period of the excitation signal.

3. Device according to claim 2, wherein the load modulation signal comprises groups of pulses of the excitation signal, the pulses of a single group being sent at a determined frequency lower than the frequency of the excitation signal.

4. Device according to claim 1, wherein the load modulation signal alternates between the following two states:

the logic “

0”

being a reference potential, and

the high impedance state.

5. Device according to claim 1, wherein the load modulation signal alternates between the following two states:

the logic “

0”

being a reference potential, and

the logic “

1”

being a direct voltage.

6. Device according to claim 1, wherein the load modulation signal is controlled by at least one port of a microprocessor.

7. Device according to claim 1, further comrpising:

an active operating mode in which the excitation signal is applied in a substantially constant manner to the antenna circuit and in which data is sent by modulating the amplitude of the magnetic field sent by the antenna circuit, the device being configured to converse with a contactless integrated circuit when it is in the active mode, and

a passive operating mode in which data is sent by applying the load modulation signal with two states to the antenna circuit using the means for simulating the operation of a contactless integrated circuit, the device being configured to converse with a contactless integrated circuit reader when it is in the passive mode.

8. Device according to claim 7, wherein in the passive mode the means for simulating the operation of a contactless integrated circuit are configured to inhibit the substantially constant application of the excitation signal to the antenna circuit, at least when the load modulation signal is not applied to the antenna circuit.

9. Device according to claim 8, wherein the inhibition of the application of the excitation signal to the antenna circuit is controlled by ports of a microprocessor.

10. Device according to claim 1, comprising means for extracting a load modulation signal sent by a contactless integrated circuit from an antenna signal present in the antenna circuit, and means for extracting an amplitude modulation signal sent by a contactless integrated circuit reader from the antenna signal.

11. Device according to claim 10, wherein the means for extracting an amplitude modulation signal and the means for extracting a load modulation signal comprise a common filter circuit coupled to the antenna circuit.

12. Method for transferring data between two contactless integrated circuit readers operating by inductive coupling, each reader comprising an antenna circuit for sending an alternating magnetic field, means for applying an alternating excitation signal to the antenna circuit, and means for modulating the amplitude of the magnetic field sent, the method comprising the steps of:

providing, at least in a first reader, means for simulating the operation of a contactless integrated circuit, arranged to apply a load modulation signal with two states to the antenna circuit of the first reader when data is to be sent by the first reader, said load modulation signal being capable of disturbing the magnetic field sent by the other reader as if said load modulation signal were a load modulation signal applied to an antenna short-circuiting switch of a contactless integrated circuit, and

making the first reader operate like a contactless integrated circuit.

13. Method according to claim 12, further comprising the step of inhibiting the application of the excitation signal to the antenna circuit of the first reader when the load modulation signal is not applied to this antenna circuit.

14. Method according to claim 12, wherein the load modulation signal comprises pulses of an alternating signal, the duration of each pulse being longer than the period of the alternating signal.

15. Method according to claim 14, wherein the load modulation signal comprises groups of pulses of the excitation signal, the pulses of a single group being sent at a determined frequency lower than the frequency of the excitation signal.

16. Method according to claim 12, wherein the load modulation signal alternates between the following two states:

the logic “

0”

being a reference potential, and

the high impedance state.

17. Method according to claim 12, wherein the load modulation signal alternates between the following two states:

the logic “

0”

being a reference potential, and

the logic “

1”

being a direct voltage.

18. Method according to claim 12 further comprising a step of providing filter means in the first reader, said filter means being configured to extract a load modulation signal sent by a contactless integrated circuit from the antenna signal of the reader and to extract an amplitude modulation signal sent by the other contactless integrated circuit reader from the antenna signal.

19. Method for sending data to a contactless integrated circuit reader, the reader sending a magnetic field, by means of a device comprising an antenna circuit and means for delivering an alternating signal for exciting the antenna circuit, the method comprising the step of:

applying a load modulation signal with two states to the antenna circuit of the device, said load modulation signal being capable of disturbing the magnetic field sent by the contactless integrated circuit reader and of being detected by the reader as if said load modulation signal were a load modulation signal applied to an antenna short-circuiting switch of a contactless integrated circuit.

20. Method according to claim 19, wherein the load modulation signal comprises pulses of the excitation signal, the duration of each pulse being longer than the period of the excitation signal.

21. Method according to claim 20, wherein the load modulation signal comprises groups of pulses of the excitation signal, the pulses of a single group being sent at a determined frequency lower than the frequency of the excitation signal.

22. Method according to claim 19, wherein the load modulation signal alternates between the following two states:

the logic “

0”

being a reference potential, and

the high impedance state.

23. Method according to claim 19, wherein the load modulation signal alternates between the following two states:

the logic “

0”

being a reference potential, and

the logic “

1”

being a direct voltage.