Patent ID: 6636374
Filing Date: 2003-10-21
Classification: G11B

Abstract:
A disc drive having:a disc mounted on a spindle, the spindle being rotatably driven by a motor at a spindle speed, the spindle speed being monitored by a frequency sensor; a head for reading and writing data on a surface of the disc, the head being suspended from an actuator arm over the disc; and a retract device comprising: a comparator circuit which compares an input signal from the frequency sensor with a predefined threshold range and outputs a comparison signal when the input signal falls outside of the predefined threshold range; a delay filter which determines a duration of the comparison signal; and a trigger, operatively coupled to the comparator circuit and the delay filter, which initiates a retract mechanism when the comparison signal falls outside of the predefined threshold range for a predetermined duration of time, the retract mechanism being configured to move the head away from the surface of the disc.