Reader for application e.g. electronic payment, has detection unit measuring electric parameter, of magnetic field transmitters, to be modified by consecutive reactive effect with presence of magnetic coupling units of portable object

摘要

The reader (100) has a detection unit to detect presence of a portable object in an action zone of the reader. A control unit controls durable activation of magnetic field transmitters in presence of object. The detection unit measures an electric parameter, of the transmitters, to be modified by consecutive reactive effect with the presence of magnetic coupling units of the object during short activation periods of the transmitters. The parameter is for example a phase difference between voltage and current in a tuned circuit comprising a coil (113) and a capacitor (114).