Disk drive with controlled actuator oscillation for release of head carriers

摘要

A magnetic recording disk drive has a startup routine that frees the recording head carriers and moves them to a parking location, such as load/unload ramp or a disk landing zone, if they are stuck to the disks when the drive motor is attempted to be started. If the drive motor does not achieve its operating speed at normal startup of the disk drive, thus indicating that static friction or other "stiction" forces are adhering the carriers to the disks, a series of alternating current pulses is applied to the actuator to dither the carriers at an initial frequency that is generally equal to or above the resonant frequency of the actuator system with stuck carriers. The frequency and amplitude of the pulses is swept downward from the initial frequency and amplitude and repeated until the drive motor rotates at its operating speed. The alternating current pulses that perform the dithering of the carriers have different amplitudes or durations so that a net force is applied to the actuator to move the carriers to the parking location.