Abstract: A magnetic recording and reproducing device is a hard disk device which writes information onto a magnetic disk (not shown), or reads information therefrom, and includes: a reproducing head; a recording head; and a magnetic head driving circuit. The magnetic head driving circuit is a circuit, by which driving of the reproducing head and the recording head is controlled, and onto which the reproducing head, a recording head driving circuit, a control unit, and a variable impedance element are integrated. This magnetic head driving circuit is switched on a time division base to a read mode during reproducing operation, and to a write mode during recording operation. The control unit reduces the impedance of the variable impedance element during the write mode.

Abstract: A magnetic recording and reproducing device is a hard disk device which writes information onto a magnetic disk (not shown), or reads information therefrom, and includes: a reproducing head; a recording head; and a magnetic head driving circuit. The magnetic head driving circuit is a circuit, by which driving of the reproducing head and the recording head is controlled, and onto which the reproducing head, a recording head driving circuit, a control unit, and a variable impedance element are integrated. This magnetic head driving circuit is switched on a time division base to a read mode during reproducing operation, and to a write mode during recording operation. The control unit reduces the impedance of the variable impedance element during the write mode.

Abstract: A recording head drive circuit drives a recording head that records information on a magnetic recording medium. A switching circuit is a H-bridge circuit which includes a plurality of transistors. The switching circuit switches direction of a write current (Iw) flowing in the recording head, in accordance with a conduction state of each transistor. A write current controller controls the write current (Iw) in the recording head. An overshoot control circuit adds an overshoot current (Ios), proportional to the write current (Iw), to the write current (Iw) flowing in the recording head, in a predetermined overshoot time period.

Abstract: The present invention provides a magnetic record reproducing device with a configuration that can decrease the fluctuation range of the current value caused by the dispersion of the resistance value of the magnetoresistive head itself. The magnetic record reproducing device is comprised of a transistor for inputting a bias voltage (Vb−), a transistor for inputting a bias voltage (Vb+) which is higher than Vb−, a magnetoresistive head 11 of which both ends are connected to the above transistors at the connection points P1 and P2, a constant current circuit which is connected to the connection point P1, a variable current circuit which is connected to the connection point P2, and a feedback circuit which controls the current of the variable current circuit according to the differential voltage (V1, V2) which is output by converting the current of the above transistors.