| 摘要 |
PROBLEM TO BE SOLVED: To restore an MR head, whose pin layer is changed by making a current larger than a bias current to flow through the MR head to an arbitrary direction in a short time. SOLUTION: A fixed bias current made to flow continuously from a first bias current circuit 3 is made to flow through an MR head 2-i by the control of a bias current control circuit 4 to flow to a negative point source or the GRD by a second bias current circuit 8 and a potential difference to be generated at both ends of the MR head 2-i at that time is amplified by a read amplifier 5-i and the D component of the output is amplified by a DC voltage amplifying circuit 7. Then, a current quantity in accordance with the output of the circuit 7, an on/off time of a current, the direction of the current and an MR head are set in a control circuit 11 according to an designation from the outside. Thus, a current having the current quantity is outputted from a constant current circuit 9, and the current is made to flow through the designated MR head 2-i to the designated direction only for the deginated time by a current control circuit 10.
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