| 摘要 |
PURPOSE:To prevent the elimination of recording information by outputting a pulse signal when a change rate signal corresponding to an hourly change rate for a reverse electromotive force signal corresponding to the reverse electromotive force of an actuator exceeds a reference signal. CONSTITUTION:Based on the energizing voltage of an actuator 10 outputted by a servo circuit 21 and the energizing current detected by a current detector 25, a reverse electromotive detecting means 30 detects the reverse electromotive signal corresponding to the reverse electromotive force of the actuator 10. Next, a comparing means 40 compares a change rate signal corresponding to the hourly change rate of the reverse electromotive signal with the reference signal set beforehand and when the change rate signal exceeds the reference signal, a pulse signal is generated. An electronic computer 20 outputs a reproducing command signal to a read/write circuit 23 immediately based on the pulse signal, reproduces the recording information of a magnetic disk 3 by a magnetic head 4 and re-records it to the storage device of the electronic computer 20. Thus, the elimination of the recording information due to the fact that a head falls on the surface of the recording support is prevented.
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