Contactless integrated circuit reader

A method for transferring data from a first contactless integrated circuit reader to a second contactless integrated circuit reader and for transferring data from the second contactless integrated circuit reader to the first contactless integrated circuit reader, the first and second contactless readers operating by inductive coupling, each of the first and second contactless readers including an antenna circuit to generate a magnetic field and an excitation circuit that delivers an alternating excitation signal to the antenna circuit, the method comprising:

• when data is transferred from the first to the second reader:
• the second reader generating a magnetic field;
• the first reader applying a data-carrying load modulation signal with two states to the antenna circuit of the first reader, the load modulation signal disturbing the magnetic field generated by the second reader;
• and
• the second reader extracting the data-carrying load modulation signal from the antenna coil of the second reader and extracting data from the data-carrying load modulation signal;
• and
• when data is transferred from the second to the first reader:
• the second reader generating a magnetic field and modulating the amplitude of the magnetic field in accordance with data to be transmitted, and
• the first reader receiving an image signal of the amplitude-modulated magnetic field and extracting data from the image signal.

A contactless integrated circuit reader comprising:

• an antenna circuit that generates a magnetic field;
• and
• an excitation circuit to deliver an alternating excitation signal to the antenna circuit,
• the reader including a first operating mode and a second operating mode,
• when in the first operating mode, the reader is configured to exchange data with a contactless integrated circuit, and
• when in the second operating mode, the reader is configured to exchange data with another contactless integrated circuit reader,
• the reader includes one of a bit and a flag to switch the reader from one of the first and second operating modes to the other of the first and second operating modes.

A data transmission system comprising a first device and a second device that each exchange data by inductive coupling, each device comprising:

• an antenna circuit that generates a magnetic field;
• an excitation circuit that delivers an alternating excitation signal to the antenna circuit,
• wherein the first device is configured to perform at least one operation in each of the three following groups of operations and the second device is configured to perform at least one complementary operation in each of the three following groups of operations, depending whatever operation is acceptable to the first device:
• operations for transmitting data:
• transmitting data to the other device by applying a load modulation signal with two states to the antenna circuit, the load modulation signal being capable of disturbing the magnetic field generated by the other device and of being detected by the other device as if the load modulation signal were a load modulation signal applied to an antenna load modulation switch of a contactless integrated circuit, and
• transmitting data to the other device by modulating the amplitude of the generated magnetic field, as if the other device were a contactless integrated circuit;
• operations for receiving data:
• not generating the magnetic field when data is to be received from the other device, and
• generating the magnetic field when data is to be received from the other device;
• and
• operations when no data is to be transmitted and when no data is to be received:
• not generating the magnetic field, and
• generating the magnetic field.

A data transmission system comprising a first device and a second device that each transmit/receive data by inductive coupling, each device comprising:

• an antenna circuit that generates a magnetic field;
• and
• an excitation circuit that delivers an alternating excitation signal to the antenna circuit,
• wherein the first device is configured to perform at least two of the following operations and the second device is configured to be responsive to at least one such operation when performed by the first device:
• transmitting data to another device by applying a load modulation signal with two states to the antenna circuit, the load modulation signal being capable of disturbing the magnetic field generated by the other device and of being detected by the other device as if the load modulation signal were a load modulation signal applied to an antenna load modulation switch of a contactless integrated circuit;
• transmitting data to another device by modulating the amplitude of the generated magnetic field, as if the other device were a contactless integrated circuit;
• not generating the magnetic field when no data is to be transmitted and when no data is to be received;
• not generating the magnetic field when data is to be received from another device;
• and
• generating the magnetic field when data is to be received from another device.