Western Digital Technologies, Inc.

Alvin W Tan

Ming Jin

Kent Douglas Anderson

Noureddine Kermiche

Galvin Chia

Shafa Dahandeh

William Arthur Sargenti, Jr

Khoa Xuan Bui

Teik E E Yeo

A disk drive is disclosed comprising a head actuated over a disk and a fly height actuator operable to control a fly height of the head in response to a fly height control signal. A touchdown operation is executed to set an operating fly height control signal by adjusting the fly height control signal until the head contacts the disk. A fly height calibration track is then read to set a fly height reference. When calibrating the operating fly height control signal, the fly height calibration track is read and the operating fly height control signal is adjusted in response to the fly height reference. When the adjusted operating fly height control signal is invalid, the touchdown operation is re-executed to reset the operating fly height control signal and then the fly height calibration track is read to reset the fly height reference.

Disk drive resetting fly height reference generated from a degrading calibration track

A method of estimating a writer/reader gap in a disk drive is disclosed. During a first revolution of the disk, a clock is synchronized to a first preamble and used to measure a write delay to write a second sync mark to the disk relative to a first sync mark. During a second revolution of the disk, the clock is again synchronized to the first preamble and used to measure a read delay required to detect the second sync mark relative to the first sync mark. The writer/reader gap is then estimated in response to the measured write delay and the measured read delay, for example, by computing a difference between the measured write delay and the measured read delay.

Estimating a writer/reader gap in a disk drive by measuring write/read times relative to a sync mark

Growing community of inventors

Irvine, CA, United States of America

Alvin W Tan