| 摘要 |
PURPOSE:To improve performance for the velocity control of a head actuator, by increasing a reference velocity output and a velocity detecting output simultaneously at a time earlier than a track pull-in time, and reducing the effect of offset generated between a D/A converter and a velocity error detection circuit. CONSTITUTION:A storage circuit 33 selects and issues the output of an area 2 when the output of a gain switching command circuit 50 is issued in a case of the number of remaining tracks NA>NA2, and the output of an area (b) in the case of the number of remaining tracks NA<=NA2. In other words, the output of the storage circuit 33 at a time when it is NA<=NA2 goes to C times the output at the time when it is NA>NA2. It means that the above operation is performed by switching a switch circuit 63, and the travel speed of the head actuator 5 can be controlled according to the reference velocity output by the output, and fast travel to a targeted track can be performed. Meanwhile, the output value of velocity error detection is reduced to 1/C and velocity deviation generated by the offset of a circuit system is reduced to 1/C. In such a way, it is possible to improve the velocity control function of the head actuator 5 and to obtain a positioning function with high accuracy.
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