| 摘要 |
PURPOSE:To magnetize unidirectionally an erasure track surely by positioning a magnetic head without fail on an erasure track in a specific exciting phase of a stepping motor and allowing a gate circuit to block an input of an information signal. CONSTITUTION:A feed screw pitch is constituted that a magnetic head 6 is moved from a wire track to an adjacent write track when an output shaft of the stepping motor 11 is turned by a 4-step angle. When exciting phase signals A', B' are at a high level, in other words, when the magnetic head 6 is placed on an erasure track, an output 33A of a NAND gate 33 goes to a low level without fail to block a write signal from a host computer 21. As a result, a coil 17 of the magnetic head 6 is excited unidirectionally from a terminal 17a to a terminal 17b regardless of the presence of a write signal from the host computer 21 and the erasure track is magnetized unidirectionally over the entire circumference.
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