Patent ID: 7180692

Claim:
A method for calibrating a fly-height actuator in a magnetic recording disk drive having a rotatable magnetic recording disk, an air-bearing slider maintained near the surface of the rotating disk, a read/write head on the slider, a digitizer for digitizing the signal from the read head, a head fly-height actuator for changing the head-disk spacing, and a fly-height controller connected to the fly-height actuator, the method comprising: determining the fly-height control signal head-disk contact (HDC) value, comprising (a) integrating the amplitude of the digitized read-head signal over a predetermined frequency range when the slider is out of contact with the surface of the rotating disk to determine a reference value; (b) applying a control signal to the fly-height actuator to reduce the head-disk spacing; (c) integrating the amplitude of the digitized read-head signal over said predetermined frequency range as a measured value as the head-disk spacing is reduced; and (d) when said measured value is greater than said reference value by a predetermined amount, recording the fly-height actuator control signal as said HDC value; measuring, for a series of fly-height control signal values, a corresponding series of digitized read-head signal amplitudes; calculating head-disk spacing from said measured read-signal amplitudes; and correlating changes in head-disk spacing with changes in fly-height actuator control signal value.