The card reader includes a peak detector that detects a peak point of a reproduced signal according to a threshold. The peak detector applies, to a first peak value to be determined, a second peak value immediately before the first peak value, a third peak value, which is the second preceding peak value with respect to the first peak value, and a next peak value. When a difference between a first intermediate value, which is a value between the third peak value and the second peak value, and a second intermediate value, which is a value between the second peak value and the first peak value, is greater than or equal to a first difference value, the peak detector ignores a first threshold, and decides the first peak value after confirming that a digital value corresponding to the next peak value has exceeded a second threshold.

This magnetic head, which reads and writes magnetic information, prevents a signal from being read between the magnetic head and the write circuit during reading of magnetic information. A card reader 1 is provided with a magnetic head 6 which reads and writes magnetic information. Bidirectional diodes 54A, 54B are arranged inside of a head case 21 of the magnetic head 6. A write signal from a write circuit 72 is inputted via the bidirectional diodes 54A, 54B to a writing coil 34 wound around a core 32 of the magnetic head 6. The bidirectional diodes 54A, 54B and a demodulation IC 61 are mounted on a first board surface 62A of a control circuit board 62, and the control circuit board 62 is fixed to the head case 21 so that the bidirectional diodes 54A, 54B and the demodulation IC 61 are covered by the head case 21.

The card reader includes a peak detector that detects a peak point of a reproduced signal according to a threshold. The peak detector applies, to a first peak value to be determined, a second peak value immediately before the first peak value, a third peak value, which is the second preceding peak value with respect to the first peak value, and a next peak value. When a difference between a first intermediate value, which is a value between the third peak value and the second peak value, and a second intermediate value, which is a value between the second peak value and the first peak value, is greater than or equal to a first difference value, the peak detector ignores a first threshold, and decides the first peak value after confirming that a digital value corresponding to the next peak value has exceeded a second threshold.

A magnetic field generator may include a magnetic field generation part including a resonance part including an inductor and a capacitor connected with each other, and which is structured so that an AC current is flowed between the inductor and the capacitor by charging electric charge to the capacitor and discharging the electric charge to generate a magnetic field by a resonance; a current direction monitoring section structured to monitor a direction of a current flowing through the inductor of the magnetic field generation part; and a judging section structured to control a timing for charging in the magnetic field generation part depending on the direction of the current flowing through the inductor which is obtained by monitoring of the current direction monitoring section.

A magnetic recording medium processing device may include a magnetic recording medium insertion slot; a medium pathway connected to the magnetic recording medium insertion slot; a magnetic head arranged to face the medium pathway; and an interference magnetic field generating device structured to generate interference magnetic fields outside the magnetic recording medium insertion slot. The interference magnetic field generating device may include a coil, a capacitor, a first power line, a second power line to which a voltage different from that to the first power line is applied, multiple switches structured to switch the connections between the first power line and the second power line of the coil and the capacitor, and a switch control unit structured to control the multiple switches.

This magnetic head, which reads and writes magnetic information, prevents a signal from being read between the magnetic head and the write circuit during reading of magnetic information. A card reader 1 is provided with a magnetic head 6 which reads and writes magnetic information. Bidirectional diodes 54A, 54B are arranged inside of a head case 21 of the magnetic head 6. A write signal from a write circuit 72 is inputted via the bidirectional diodes 54A, 54B to a writing coil 34 wound around a core 32 of the magnetic head 6. The bidirectional diodes 54A, 54B and a demodulation IC 61 are mounted on a first board surface 62A of a control circuit board 62, and the control circuit board 62 is fixed to the head case 21 so that the bidirectional diodes 54A, 54B and the demodulation IC 61 are covered by the head case 21.

A magnetic head to detect a change of a magnetic field caused by a passing of a magnetic recording medium may include a head main body including a core provided with a gap and a coil which is wound around the core; a demodulation circuit structured to demodulate an analog signal outputted from the coil; an encryption circuit structured to encrypt a demodulated signal outputted from the demodulation circuit; a head case in which the head main body is accommodated; and a filter circuit which is connected between the coil and the demodulation circuit and is structured to remove noise from the analog signal. An electronic component which structures the filter circuit may be accommodated in the head case.

A card reader may include a conveyance passage; an optical sensor; a first circuit board; a second circuit board; a first cover member; a second cover member; a first frame; and a second frame comprising a conveyance face on a second direction side of the card conveyance passage. The first frame may include a first transmission hole, and the first frame may be attached with one of the first circuit board and the second circuit board. The second frame may include a second transmission hole, and the second frame may be attached with the other of the first circuit board and the second circuit board. The first cover member may be fixed to the first circuit board so as to cover the entire light emitting element; and the second cover member may be fixed to the second circuit board so as to cover the entire light receiving element.

A magnetic recording medium processing device may include a magnetic recording medium insertion slot; a medium pathway connected to the magnetic recording medium insertion slot; a magnetic head arranged to face the medium pathway; and an interference magnetic field generating device structured to generate interference magnetic fields outside the magnetic recording medium insertion slot. The interference magnetic field generating device may include a coil, a capacitor, a first power line, a second power line to which a voltage different from that to the first power line is applied, multiple switches structured to switch the connections between the first power line and the second power line of the coil and the capacitor, and a switch control unit structured to control the multiple switches.

A method for manufacturing a magnetic core module in a magnetic head, the magnetic core module and the magnetic head. The method for manufacturing the magnetic core module includes: a process for placing a magnetic core group in a holder mold cavity as an insert; and a process for injection-molding in the holder mold cavity. A method for manufacturing the magnetic core module allows the magnetic core group and the holder to be integrally injection-molded with a method of injection molding which uses the magnetic core group as an insert. The method simplifies the process of manufacturing a magnetic head to improve production efficiency, and saves labor and production costs. Further, the method prevents failures such as positional displacement and scattering of magnetic cores, which tends to occur when assembling thin and small magnetic cores, and ensures an ideal yield for a product.