Card reader and foreign matter detection method thereof

A method of detecting a foreign matter in a card reader comprising:

• a card passage through which a card inserted from a card insertion port passes, the card passage being connected to the card insertion port;
• a magnetic head configured at least one of:
• to record magnetic data for a magnetic stripe of the card;
• and to read the magnetic data from the magnetic stripe;
• a capacitive sensor provided in contact with the card passage;
• a movable structure with a distance to the capacitive sensor being variable;
• and a drive and detection circuit configured to drive the capacitive sensor and obtain a capacitance value to be detected by the capacitive sensor, wherein the capacitive sensor is divided into a plurality of regions each of which is capable of detecting a capacitance, and includes a switch circuit configured to electrically connect and disconnect each region, and the drive and detection circuit is connected to one of the plurality of regions of the capacitive sensor, the method comprising the steps of:
• detecting a foreign matter, based on a detection amount in the drive and detection circuit while the switch circuit is rendered non-conducting;
• and
• detecting the foreign matter again, based on the detection amount in the drive and detection circuit, and thereafter, rendering the switch circuit non-conducting if there is no response in the foreign matter detection, while the switch circuit is rendered conducting.