| 摘要 |
PURPOSE:To prevent the erasure accident of the information stored on a disk by detecting the pulse intervals of a revolution pulse signal in the braking stage of a device. CONSTITUTION:The coefft. of friction of a disk 3 and a head 6 increases and provides large braking force in the braking stage of a rotating device 2 if the relation between the disk and head are abnormal, the rotating speed of the disk 3 is, therefore, slower in the abnormal stage than in the normal stage when the disk 3 rotates by a prescribed number after the rotational driving of the disk 3 is stopped. The pulse intervals of the revolution pulse signal are measured by a revolution detector 8 and counter means 22, 23 to detect the normality and abnormality. A slight increase of the probability to generate the erasure accident of the information stored on the disk arising from the accident to allow the head to float from the disk is thereby detected and the erasure accident is prevented.
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