Western Digital Technologies, Inc.

Yun Hong

Guoxiao Guo

Siri S Weerasooriya

Wei Guo

Brian P Rigney

Jiangang Liang

Charles A Park

Michael A Chang

Kei Yasuna

Lawrence Matthias Bryant

Xiaokun L Chew

Yilin Cai

Dan Wang

Various illustrative aspects are directed to a data storage device, method, and one or more processing devices that are configured to: determine a first burst value based on a first set of bursts within a servo pattern, the first set of bursts comprising two bursts having a first length in a longitudinal direction of a track containing the servo pattern and at least one burst having a second length in the longitudinal direction of the track and different than the first length; determine a second burst value based on a second set of bursts within the servo pattern, the second set of bursts comprising at least two bursts having the second length; generate a position error signal (PES) based on the determined first burst value and the determined second burst value; and control a position of at least one head among the one or more heads based on the PES.

Data storage device with symmetric split burst servo pattern

Various illustrative aspects are directed to a data storage device, comprising one or more disks; an actuator mechanism configured to position one or more heads proximate to a corresponding disk surface of the one or more disks; and one or more processing devices. The one or more processing devices are configured to apply a pre-bias current to the assistive energy emitter at a first value while the selected head is positioned proximate to one or more spiral patterns on the corresponding disk surface. The one or more processing devices are further configured to apply the pre-bias current to the assistive energy emitter at a boosted value while the selected head is not positioned proximate to the one or more spiral patterns, wherein the boosted value is greater than the first value.

Energy-assisted magnetic recording data storage device with assistive energy pre-heating for writing servo patterns

A data storage device is disclosed comprising a first disk surface comprising servo tracks defined by servo sectors and recorded at a first radial density, and a first head actuated over the first disk surface. A servo sector on the first disk surface is read to generate a first physical position measurement that is converted into a first virtual position measurement corresponding to a nominal radial density of servo tracks different from the first radial density. The first head is servoed over the first disk surface based on the first virtual position measurement.

Data storage device servoing heads based on virtual servo tracks

A disk drive is disclosed comprising a first head actuated over a first disk surface and a second head actuated over a second disk surface. A first servo sector of the first disk surface is read to generate a read signal which is processed to generate a first phase error. A first clock is generated at a frequency proximate a servo data rate of the first data sector. Read signal samples are synchronized in response to the first phase error and the first clock to generate synchronous samples, and servo data in the first servo sector is detected in response to the synchronous samples. The read signal is processed to generate a second phase error, a second clock is generated in response to the second phase error, and a spiral servo track is written to the second disk surface using the second clock.

Servoing on zoned concentric servo sectors of a first disk surface to write a spiral servo track to a second disk surface

A method is disclosed of servo writing a disk drive comprising a first head actuated over a first disk surface, and a second head actuated over a second disk surface. A first repeatable runout (RRO) of the first disk surface is measured, and a seek is performed to seek the first head over the first disk surface in response to the measured first RRO while writing a first spiral track to the second disk surface using the second head. As a result, the first spiral track comprises a second RRO that substantially matches the first RRO of the first disk surface.

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San Jose, CA, United States of America

Yun Hong