CROSS REFERENCE TO RELATED APPLICATION

The present application claims priority under 35 U.S.C. § 119 to Japanese Application No. 2019-107794 filed on Jun. 10, 2019, and the entire content of which is incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to a card reader structured to perform at least one of reading and writing of magnetic data to a magnetic card and a control method of the card reader.

BACKGROUND

A card reader structured to perform reading of magnetic data recorded in a magnetic card and writing of magnetic data to the magnetic card has been widely used in an ATM (Automated teller machine) and the like. In the card reader, a magnetic head is provided for reading and writing of magnetic data. However, so-called skimming may be performed in which, in addition to a normal magnetic head, an illegal magnetic head is disposed in the card reader by a criminal to illegally acquire magnetic data. In order to detect a skimming act, a technique has been proposed that a metal detection sensor is provided in an inside of the card reader and a foreign matter such as a skimming magnetic head having been disposed is detected by the metal detection sensor. The metal detection sensor has been known which is, for example, structured so that a detection coil and a pair of excitation coils are wound around a core made of magnetic material and, when an object including metal is located in the vicinity of the core, an output voltage from the detection coil is increased. In a state that a magnetic card does not exist in the inside of the card reader, when it is detected whether an output voltage value of the metal detection sensor exceeds a foreign matter detection slice value which is a threshold value or not, presence or absence of a foreign matter can be determined. In Japanese Patent Laid-Open No. 2015-82307 (Patent Literature 1), a technique is disclosed that, in order to detect a foreign matter while compensating for a variation of an output of a metal detection sensor due to change of ambient temperature, instead of simply comparing a foreign matter detection slice value with an output of the metal detection sensor, it is determined that a foreign matter has been detected when a difference “ΔV” between a current measured value “V” by the metal detection sensor and a reference voltage value “Vb” exceeds a reference value “ΔVd” and, when the difference “ΔV” is not more than a second reference value “ΔVb”, the current measured value “V” itself is set to be the new reference voltage value “Vb” which is used in the next foreign matter detection.

When a magnetic card wetted with water is inserted and pulled out from a card reader, water droplets may be left in the card reader. Alternatively, when a card reader is installed in an environment exposed to wind and rain, water droplets may enter into an inside of the card reader through a card insertion port. When water droplets have entered in the inside of the card reader, the water droplets having entered may be erroneously detected as a foreign matter depending on characteristics of a metal detection sensor.

SUMMARY

In view of the problem described above, at least an embodiment of the present invention may provide a card reader structured to reduce erroneous detection of water entered into an inside of the card reader as a foreign matter, and provide a control method of the card reader.

To solve the above-mentioned problem, at least an embodiment of the present invention may provide a card reader structured to perform at least one of reading of magnetic data recorded in a card and writing of magnetic data to the card. The card reader may include a metal detection sensor structured to detect a foreign matter including metal, a judgment part configured to compare an output of the metal detection sensor with a predetermined threshold value to determine whether abnormality has occurred or not, and an abnormality determination part configured to obtain a difference between a reference value and an output of the metal detection sensor in a case that the judgment part determines that the abnormality has occurred to determine as the foreign matter in a state that the difference is within a stable determination width.

In the card reader in accordance with at least an embodiment of the present invention, when it is determined to be abnormal by comparing an output of the metal detection sensor with a predetermined threshold value, a difference between the output of the metal detection sensor and a reference value for determination is obtained and, when the difference is within a stable determination width, it is determined that a foreign matter exists. Therefore, erroneous detection of water entered in the inside of the card reader as a foreign matter is reduced and reliability of the card reader can be enhanced.

In the card reader in accordance with at least an embodiment of the present invention, it may be preferable that the abnormality determination part determines that the foreign matter exists in a case that the state that the difference is within the stable determination width has continued over a predetermined time period. In a case of erroneous detection due to water, a value of an output of the metal detection sensor is not stable according to a discharge and the like of the water. Therefore, it can be determined that a foreign matter exists when a state that the difference between the output of the metal detection sensor and a reference value for determination is within the stable determination width has continued over a predetermined time period. Accordingly, a foreign matter can be surely detected while erroneous detection is reduced.

In the card reader in accordance with at least an embodiment of the present invention, it may be preferable that the judgment part updates the reference value with the output of the metal detection sensor in a case that the judgment part determines to be no abnormality as a result of comparing the output of the metal detection sensor with the predetermined threshold value. According to this structure, an effect due to a characteristic change of the metal detection sensor with time can be reduced. Further, it may be preferable that the abnormality determination part updates the reference value with the output of the metal detection sensor when the difference exceeds the stable determination width. According to this structure, the reference value for determining whether it is detection of a foreign matter or it is erroneous detection due to water droplets or the like is updated in accordance with an actual circumstance and thus, erroneous detection can be reduced.

Further, at least an embodiment of the present invention may provide a control method of a card reader structured to perform at least one of reading of magnetic data recorded in a card and writing of magnetic data to the card. The control method may include acquiring an output value of a metal detection sensor structured to detect a foreign matter including metal in a state that the card is not inserted into the card reader, judging whether abnormality has occurred or not by comparing the output value with a predetermined threshold value, obtaining a difference between a reference value and an output value of the metal detection sensor when it is determined that the abnormality has occurred, and determining that a foreign matter exists when the difference is within a stable determination width.

According to the control method of at least an embodiment of the present invention, an output value of the metal detection sensor is compared with a predetermined threshold value and thereby, when it is determined to be abnormal, a difference between the output value of the metal detection sensor and a reference value for determination is obtained and, when the difference is within a stable determination width, it is determined that a foreign matter exists. Therefore, erroneous detection of water entered in the inside of the card reader as a foreign matter is reduced and reliability of the card reader is enhanced.

In the control method in accordance with at least an embodiment of the present invention, it may be preferable that the output value is repeatedly acquired at a predetermined time interval in a state that the card is not inserted into the card reader. When the output value of the metal detection sensor is repeatedly acquired at a predetermined time interval, in an existing card reader whose control part is, for example, configured of a microprocessor, the control method of at least an embodiment of the present invention can be executed without adding or changing the hardware. Further, in the control method in accordance with at least an embodiment of the present invention, it may be preferable that it is determined that a foreign matter exists in a case that the state that the difference is within the stable determination width has continued over a predetermined time period. In a case of erroneous detection due to water, a value of the output value of the metal detection sensor is not stable according to discharge and the like of the water. Therefore, it can be determined that a foreign matter exists when a state that the difference between the output value of the metal detection sensor and a reference value for determination is within the stable determination width has continued over a predetermined time period. Accordingly, a foreign matter can be surely detected while erroneous detection is reduced.

In the control method in accordance with at least an embodiment of the present invention, it may be preferable that, in a case that it is not determined to be abnormal as a result of comparing the output value with the threshold value, the reference value is updated with the output value. According to this method, an effect due to a characteristic change of the metal detection sensor with time can be reduced. Further, it may be preferable that the reference value is updated with the output value when the difference exceeds the stable determination width. According to this method, the reference value for determining whether it is detection of a foreign matter or it is erroneous detection due to water droplets or the like can be updated in accordance with an actual circumstance and thus, erroneous detection can be reduced.

Effects of the Invention

According to at least an embodiment of the present invention, erroneous detection of water entered in the inside of the card reader as a foreign matter is reduced and reliability of the card reader is enhanced.

Other features and advantages of the invention will be apparent from the following detailed description, taken in conjunction with the accompanying drawings that illustrate, by way of example, various features of embodiments of the invention.

