Abstract: A disk drive with means to prevent accidental landing of a head/slider on the disk surface is described. In one embodiment a shock sensor is provided to sense external shocks received by the mechanism. During loading (positioning) of the actuator bearing the head/slider over the disk, if a shock is sensed, loading is stopped and an immediate unloading is performed to return the actuator to the withdrawn position. In another embodiment the unload operation is performed when the rotational speed of the disk is changed. In another embodiment the unload operation is performed when the rotational speed of the disk drops below a threshold. A circuit and method for detecting when the rotational speed of the disk drops below a threshold is also provided. The unloading in the various embodiments may be performed using velocity control or without velocity control.

Abstract: The invention relates to magnetic recording devices and a method for unsticking a head/slider assembly stuck on the surface of a magnetic recording disk. The method includes a first step which determines a resonant frequency of a mechanical system containing a magnetic recording disk, a head/slider assembly and a flexible support arm in which the resonant frequency of the mechanical system varies depending upon a position of the head/slider assembly on the surface of the magnetic recording disk, and a second step which oscillates the spindle motor and/or the voice coil motor at the resonant frequency to unstick the head/slider assembly from the surface of the magnetic recording disk.