Western Digital Technologies, Inc.

Agency for Science, Technology and Research

University of California

Seagate Technology Incorporated

Guoxiao Guo

Jie Yu

Wei Guo

Michael A Chang

Kei Yasuna

Wei Xi

Charles A Park

Abhishek Dhanda

Jianguo Zhou

Joey Martin Poss

Scott A Ottele

Duc H Banh

Richard Conway

Wai Ee Wong

Russ A Quisenberry

Yun Hong

William Bernard Boyle

Yanning Liu

Donald Joseph Brunnett

Gary Allan Herbst

Jun Xu

Richard Koonwai Wong

Jingliang Zhang

Sanghoon Chu

Ryan P Mayo

Shuyu Cao

Hui Li

David Scott C Amiss

Weldon Mark Hanson

Shaomin Xiong

Jack M Chue

Eric S Bjornson

Min Chen

Kuang-Yang Tu

Masaru Furukawa

Teik Ee Yeo

John W Vanlaanen

Xu Qi Chen

Davide Giovenzana

Jianyi Wang

Zhimin He

Jason Laks

Dan Wang

Ling Chih Wei

Xiaotian Xu

Honge Wang

Toshiki Hirano

Erhard Theodor Schreck

Siri S Weerasooriya

Qinghua Zeng

Qing Li

Brian P Rigney

Young-Hoon Kim

Ian Robson McFadyen

Jenghung Chen

Edgar D Sheh

Carl E Barlow

Soo-Choon Kang

Stanley H Shepherd

Jianbin Nie

Xiaokun L Chew

Yiming Chen

Huanxiang Ruan

Jonathan V Nguyen

Prakash Balasubramaniam

Masayoshi Tomizuka

Hongchao Tim Zhao

John Yin Kwong Li

Junpeng Niu

Steven C Smith

Teddy T C Chen

Jie Wan

Philip S Gordon

Eugene Chun-Tsing Wu

Jern Khang Tan

Qingwei Jia

Qing Wei Jia

Minghui Zheng

Triet Tieu

Yakov M Lifschitz

Teddy T Chen

Jinchuan Zheng

Teddy Tc Chen

Tuong M Vu

Ichiro Yokokawa

Branislav Hredzak

Tianyu Jiang

Kun Ma

Eng Hong Ong

Abdullah Al Mamun

Weichun Ye

Hua Qian

EngHong Ong

Eugene C Wu

Due H Banh

Various illustrative aspects are directed to a data storage device, method, and one or more processing devices that are configured to: obtain a first value of a first servo burst signal and a second value of a second servo burst signal associated with a servo pattern in a track of the disk; calculate an adjusted first value and an adjusted second value by adjusting one or both of the first value and the second value based on a measure of servo pattern distortion associated with the track; generate a position error signal (PES) using the adjusted first value and the adjusted second value; and control a position of the head over the track using the PES.

Data storage device with servo burst signal correction for mitigating effects of servo pattern distortion

Example control circuitry, data storage devices, and methods for parallel self-servo writing of interleaved servo patterns in a data storage device are described. The data storage device may include multiple heads actuated over different surfaces of a data storage device and receive read signals from two different heads over two different surfaces in parallel. The servo wedges of the two surfaces may be offset to enable independent determination of phase while writing servo patterns in parallel to the two surfaces using their respective heads.

Interleaved servo patterns in a data storage device

Example circuits, data storage devices, and methods to provide parallel self-servo write in a data storage device are described. The data storage device may include multiple heads actuated over respective surfaces of storage media and at least two preamplifiers and read paths to a channel circuit. Control circuitry may select heads connected through different preamplifiers for parallel self-servo write and receive read signals from the selected heads in parallel. These read signals, which may be based on self-servo write reference spirals previously written to the storage media, may be used to determine respective position error signals for the two heads and control their respective positions with corresponding control signals to a shared voice control motor and respective micro and/or milli actuators on the arms supporting the heads.

Parallel self-servo write circuitry in a data storage device

Example storage preamplifier circuits, data storage devices, and methods for parallel self-servo write are described. The data storage device may include a pair of preamplifier circuits electrically connected to respective banks of read heads actuated over a storage media surfaces. In read/write operation, each preamplifier circuit may selectively and sequentially provide read signals from a selected head to a pair of read channel interfaces. In self-servo write operation, each preamplifier circuit may selectively and in parallel provide read signals from a selected head in their corresponding banks of read heads to the pair of read channel interfaces. For example, the pair of read channel interfaces for two-dimensional magnetic recording may receive read signals from one read sensor in a head in the first bank of heads and another read sensor for another head in the second bank of heads.

Preamplifier circuit for parallel self-servo write

Example servo interface circuitry, data storage devices, and methods to provide parallel self-servo write in a data storage device are described. The data storage device may include servo control circuitry that includes at least three digital-analog converters to provide control signals to the voice control motor (VCM) and arm actuators (e.g., micro actuators and milli actuators) of the data storage device. In data read/write mode, one actuator control signal controls the milli actuator for the target arm/head and another actuator control signal controls the micro actuator for the target arm/head. In self-servo write mode, one actuator control signal controls the micro actuator for one target arm/head and the other actuator control signal controls the micro actuator for another target arm/head for parallel self-servo writing.

Servo interface circuitry for parallel self-servo write

Example control circuitry, data storage devices, and methods for parallel self-servo write in a data storage device are described. The data storage device may include multiple heads actuated over different surfaces of a data storage device and receive read signals from two different heads over two different surfaces in parallel. Position error signals may be determined from each read signal and corresponding position compensation values may be determined for their respective microactuators. Application of these compensation values may maintain their relative positions for parallel writing of servo tracks based on their respective spiral reference patterns and TPI settings.

Parallel self-servo write in a data storage device

Various illustrative aspects are directed to a data storage device including one or more disks, an actuator mechanism configured to position a selected head among one or more heads proximate to a corresponding disk surface among the one or more disks, the selected head comprising a write element and an assistive energy emitter, and one or more processing devices configured to, individually or in combination: apply an assistive energy current to the assistive energy emitter while refraining from applying a write current to the write element, and vary a level of the assistive energy current over time while refraining from applying the write current to the write element.

Energy-assisted magnetic recording data storage device with opportunistic boosted laser pre-biasing

Example control circuitry, data storage devices, and methods for determining wedge repeatable runout correction values for interleaved servo patterns in a data storage device are described. The data storage device may include multiple heads actuated over different surfaces of a data storage device and receive read signals from two different heads over two different surfaces in parallel. The servo wedges of the two surfaces may be offset to enable parallel learning of wedge repeatable runout correction values.

Wedge repeatable runout correction for interleaved servo patterns in a data storage device

A magnetic media library drive includes a first disk medium fixed to a spindle, a first read-write transducer configured to operate on the first disk, a second read-write transducer configured to operate on a surface of a single removable second disk medium installed over the first disk, and electronic controller circuitry configured to cause: while the first transducer is servo-positioning from a master servo pattern from the first disk, the second transducer servo-writes a product servo pattern, based on the master servo pattern, to the surface of the second disk. The removable second disk can be removed, turned over, and secured to the spindle, whereby the self-servo writing procedure can be performed on the other side of the second disk based on the master servo pattern on the first disk.

Servo-write for magnetic disk media archival data storage system

Various illustrative aspects are directed to a data storage device, method, and one or more processing devices that are configured to: write a plurality of test servo patterns using a plurality of different write settings; select one of the plurality of different write settings based on analyzing the plurality of test servo patterns for mode hop; and write a plurality of final servo patterns using the selected one of the plurality of different write settings.

Data storage device with embedded mode hop predictor patterns

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 selected head comprises a write element and an assistive energy emitter. The one or more processing devices are configured to apply an assistive energy current to the assistive energy emitter while refraining from applying a write current to the write element.

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

Example storage medium servo patterns, data storage devices, and methods to provide servo tracks with continuously varying frequency in a data storage device are described. The data storage device may include storage media, such as magnetic disks, having servo sectors that define servo tracks, where adjacent servo tracks have continuously varying frequency as the head moves from one servo track to the next. As the head is actuated over the storage medium, a target track frequency may be determined based on the radial position of a target servo track and the channel frequency may be set to the target track frequency to follow the target servo track.

Continuous frequency servo in a data storage device

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: select a sector on the corresponding disk surface to which to write data, wherein the sector is selected in accordance with a data erosion mitigation pattern; and output, while the head is positioned proximate to a preceding sector that precedes the selected sector, a laser pre-bias current to a laser-generating component of the head, wherein the laser pre-bias current is sufficient to induce significant data erosion on the preceding sector.

Data storage device with enhanced management of laser pre-bias and logic block addressing in heat-assisted magnetic recording

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

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Irvine, CA, United States of America

Guoxiao Guo