US Patent 10007814 Card reader and control method for card reader

A card reader may include a card insertion part comprising a card insertion port is formed; a plurality of metal sensors structured to detect whether a foreign matter including metal material has been attached near the card insertion part; and a control section with which the plurality of the metal sensors are connected. The metal sensor may include a core formed of magnetic material and an excitation coil and a detection coil which are wound around the core. The control section may be structured to supply a current to each of the excitation coils of the plurality of the metal sensors at different timings.