| 摘要 |
Lead wires are extended from phase coils of a head control motor, so that their effective reactances may be varied, and reactance selection circuits are additionally provided to switch values of the reactances of the phase coils to a low value. A vector position is sequentially delivered to phase current generators by a processor for designating the vector position, so that a head is displaced to a desired position. Thereafter, the reactances of the phase coils are switched to a high value by the reactance selection circuits, and then the vector position corresponding to the normal one is applied to the phase current generators, so that the head is so controlled as to be positioned at its normal position on a track on a disc and is maintained at this position. During the time of displacement of the head across the tracks, it is ensured that the head control motor is driven at a high response speed.
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