Hitachi Global Storage Technologies Netherlands B.v.

Alex Shteyn

Weidong Huang

Xiaodong Che

Terence Tin-Lok Lam

Zhong-heng Lin

A system and method for determining head-disk contact (HDC) in a magnetic recording disk drive uses the signal from the magnetoresistive (MR) read head. The analog MR signal is digitized and input to a digital signal processor with circuitry and/or software for integrating the signal amplitude over a low-frequency range. The calculated value from the integration when the slider is out-of-contact with the disk is a reference value. The same integration is then performed during operation of the disk drive and the measured value is compared to the reference value. If the measured value exceeds the reference value by some predetermined amount, this is an indication of the onset of HDC or that HDC has occurred. The method can be used in head-disk testers to facilitate the design and testing of disk drive components, such as slider-suspension assemblies and fly-height actuators located on the slider to alter the head-disk spacing, and in disk drives to control fly-height actuators and to take corrective action prior to HDC.

System and method for determining head-disk contact in a magnetic recording disk drive

A system and method for calibrating and controlling a magnetic recording disk drive fly-height actuator uses the signal from the magnetoresistive (MR) read head to determine head-disk contact (HDC). The MR signal is measured over a low-frequency range, with the slider out-of-contact with the disk, to develop a reference value. The MR signal is then measured over the same low-frequency range and if it exceeds the reference value by some predetermined amount, this is an indication of HDC. The fly-height actuator control signal value for HDC is recorded and thus corresponds to a head-disk spacing of zero. The calibration method also determines the sensitivity of head-disk spacing to the fly-height actuator control signal by measuring a series of MR read signal amplitudes for a corresponding series of control signals. The fly-height actuator is calibrated from the sensitivity and the value of control signal that results in zero head-disk spacing, and can then be controlled to move the head to a desired fly height and maintain it at the desired fly height.

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Sunnyvale, CA, United States of America

Alex Shteyn