Patent ID: 6905074

Claim:
A contactless integrated circuit reader comprising a tuned antenna coil for emitting an oscillating magnetic field and means for detecting the presence of a contactless integrated circuit comprising an antenna coil within a communication perimeter of the reader, the detection means comprising: means for emitting short magnetic field pulses, means for extracting from the antenna coil an envelope signal having envelope pulses corresponding to the magnetic field pulses, and means for monitoring the amplitude of the envelope pulses, configured to detect an object the introduction of which into the communication perimeter of the reader substantially de-tunes the antenna coil of the integrated circuit reader, and comprise: means for, during a calibration phase, determining a detection threshold using the mean value of the amplitude of the envelope pulses, so that the amplitude of the envelope pulses during the calibration phase is substantially above the detection threshold while being very close to the detection threshold, and means for, during a detection phase, detecting at least one envelope pulse having an amplitude below the detection threshold, to deduce therefrom that an object has been introduced into the communication perimeter relative to the time at which the calibration phase was performed, the reader being arranged to send an identification request when an envelope pulse has an amplitude below the detection threshold, so as to determine whether the object that has entered the communication perimeter is a contactless integrated circuit or not.