Card reader and foreign matter detection method thereof

A card reader for use with a card having a magnetic stripe, the card reader comprising:

• a card insertion port;
• a card passage through which the card inserted from the card insertion port passes, the card passage being connected to the card insertion port;
• a magnetic head configured to perform at least one of:
• recording magnetic data to the magnetic stripe of the card;
• and reading magnetic data from the magnetic stripe of the card;
• a capacitive sensor provided in contact with the card passage;
• and
• a movable structure structured such that a distance between the movable structure and the capacitive sensor is variable,
• wherein
• the capacitive sensor comprises a plurality of regions, each of the plurality of regions being structured to detect a capacitance, and a switch circuit configured to electrically connect and disconnect each region of the plurality of regions,
• the plurality of regions comprises a first region arranged in a position and a second region, the first region being arranged in a position less susceptible to an influence of a movement of the movable structure than a position of the second region,
• the card reader further comprises:
• a drive and detection circuit configured to drive the capacitive sensor and obtain a capacitance value to be detected by the capacitive sensor such that the drive and detection circuit is connected to the first region, and
• a control circuit configured to control the switch circuit and detect the foreign matter based on an output from the drive and detection circuit, and
• the control circuit unceasingly connects the first region to the drive and detection circuit to detect the foreign matter.

A card reader for use with a card having a magnetic stripe, the card reader comprising:

• a card insertion port;
• a card passage through which the card inserted from the card insertion port passes, the card passage being connected to the card insertion port;
• a magnetic head configured to perform at least one of:
• recording magnetic data to the magnetic stripe of the card;
• and reading magnetic data from the magnetic stripe of the card;
• a capacitive sensor provided in contact with the card passage;
• and
• a movable structure structured such that a distance between the movable structure and the capacitive sensor is variable,
• wherein
• the capacitive sensor comprises a plurality of regions, each of the plurality of regions being structured to detect a capacitance, and a switch circuit configured to electrically connect and disconnect each region of the plurality of regions,
• the plurality of regions comprises a first region arranged in a position and a second region, the first region being arranged in a position less susceptible to an influence of a movement of the movable structure than a position of the second region,
• the card reader further comprises 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 drive and detection circuit is connected to the first region,
• other regions of the plurality of regions are connected in series via the switch circuit to a region of the plurality of regions connected to the drive and detection circuit,
• the card reader further comprises a control circuit configured to control the switch circuit and detect a foreign matter based on an output from the drive and detection circuit, and
• the control circuit unceasingly connects the first region to the drive and detection circuit to detect the foreign matter.