Western Digital Technologies, Inc.

Hitachi Global Storage Technologies Netherlands B.v.

Hgst Netherlands, B.v.

International Business Machines Corporation

Other

Gary Allan Herbst

David Timothy Flynn

Guoxiao Guo

James Bowling French, Jr

Scott A Ottele

Timothy John Everett

Bruce Alexander Wilson

Bernhard E Knigge

Joey Martin Poss

Tetsuo Semba

Michael Anthony Moser

Richard Conway

James B French, Jr

Louis Joseph Serrano

Toshiki Hirano

Mark Delorman Schultz

Jonathan Darrel Coker

Masahito Kobayashi

Peter Michael Baumgart

Satoshi Yamamoto

Charles A Park

Chuanwen Ji

Matthew Taylor White

Abhishek Dhanda

Charles Mathew Mate

Kirk Hwang

Kevin Tzou

Bryan Rowan

Jong-Ming Lin

Scott Arthur Thomas

Anthony Edwin Welter

Masaki Kohno

Austin Striegel

Blake O Finstad

Jason Laks

Yuanyuan Zhao

Shravankumar Girish Bhat

Jong Ming Lin

Charles Raymond Davis

Kishan K Kumbia

Jonathan Darrell Coker

David M Jones

Jim French

Yongzhi Liu

Naoyuki Minami

Hung Phan

Kenneth James Dougherty

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 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

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 heads proximate to a recording medium of the disks; a spindle motor configured for rotating the one or more disks; and one or more processing devices comprising a servo control processor. The servo control processor is configured to receive a spindle speed error signal indicative of an error in a rotational speed of the spindle motor. The servo control processor is further configured to output an initial frequency offset signal, wherein the initial frequency offset signal is proportional to the spindle speed error signal.

Data storage device with servo control processor with initial fast lock of disk lock clock

A data storage device comprises a disk having a plurality of data tracks and a plurality of servo wedges wherein the plurality of servo wedges comprise a plurality of wedge repeatable runout (WRRO) fields configured to store a plurality of WRRO compensation values in connection with the plurality of data tracks. The data storage device may also include a read/write head configured to be actuated over the disk, and a controller configured to gather position error signal (PES) data needed for computation of the WRRO compensation values during a field operation of the data storage device. The data storage device may be further configured to adjust a position of the read/write head based on the WRRO compensation values.

Data storage device integrating wedge repeatable runout (WRRO) learning into data recovery procedure (DRP)

A data storage device is disclosed comprising a head actuated over a disk surface comprising a plurality of servo sectors, wherein each servo sector comprises a servo burst field. Across a first radial band of servo tracks, the servo burst field comprises a first length, and across a second radial band of servo tracks, the servo burst field comprises a second length longer than the first length. When the head is over the first radial band of the servo tracks, the head is servoed over the disk surface based on the first read element reading a first servo sector and the second read element concurrently reading a second servo sector different from the first servo sector. When the head is over the second radial band of the servo tracks, the head is servoed over the disk surface based on the first read element reading a third servo sector.

Data storage device comprising extended servo burst field over part of a disk surface

A data storage device is disclosed comprising a first disk surface comprising a plurality of servo tracks, a first head actuated over the first disk surface, wherein the first head comprises a first read element, and a second read element. During a write operation first servo data in a first servo track is read using the first read element to generate a first read signal, and the first head is servoed over the first servo track based on the first read signal while writing data to the first disk surface. Second servo data is read using the second read element to generate a second read signal, and the write operation is aborted when the first read signal indicates a shock event is affecting the servoing of the first head and the second read signal confirms the shock event.

Data storage device conditioning write abort based on secondary read signal

A data storage device is disclosed comprising a first disk comprising first servo sectors A-Adistributed around a circumference of the first disk, and a second disk comprising second servo sectors B-Bdistributed around a circumference of the second disk, wherein the second servo sectors B-Bare offset circumferentially from the first servo sectors A-A. While the first and second disks are rotating second servo information is transmitted from a second servo channel to a first servo channel. One of the first servo sectors Ai is read to generate first servo information, and a first command value is generated based on the first servo information and the second servo information, wherein a first actuator is controlled based on the first command value.

Data storage device communicating servo information between servo channels of multiple actuators

A two-dimensional magnetic recording (TDMR) disk drive has a disk with servo tracks with a track pitch that varies across the radius of the disk. The servo track pitch (STP) is related to the cross-track spacing (CTS) of the multiple read sensors in the TDMR head structure. The CTS is given by the equation: CTS=(CTO)cos &#x3b8;+(ATO)sin &#x3b8;, where &#x3b8; is the skew angle, and CTO is the cross-track spacing and ATO the along-the-track spacing of the read sensors at zero skew angle. The optimal variable STP profile results in track misregistration reduction because it allows each read sensor to read a different servo half-track and thus noise sources not correlated to noise sources read by the other read sensors. The servo tracks may be arranged into a plurality of annular bands, with the STP in each band being fixed and different from the STP in the other bands.

Two-dimensional magnetic recording (TDMR) disk drive with varying servo track pitch

Disk drives are described that include a hybrid servo patterns in which the augmented servo burst fields, which can be Integrated Servo sequences, that provide the PES and also supply additional information such as a SAM, LSBs of the track identifier (TID), sector number, depending on the specific embodiment. Embodiments without write-to-read gaps before the servo sector SIDs are described. The augmented servo burst fields can be read after gapless writing of the preceding data area. For seeking operations the needed bits of the TID without having to detect or decode the Integrated Servo sequences or other augmented servo burst fields. Depending on the embodiment all or the most significant bits of the track identifier can be obtained during seeks by reading the TID fields passing under a read head as the read head moves across tracks without having to detect or decode the Integrated Servo sequences.

Servo systems with augmented servo bursts

A disk drive is described with a single servo master timer that is used to control timing critical signals such as servo gate, SAM windows, channel power save, PREAMP power save and so on. The master timer is adjusted to compensate for SAM detection errors (early, late or missed) and provides improved servo timing quality. In an embodiment the adjustable master timer can be selectably clocked by either the DLC/DSW clock or the system clock.

Disk drive with servo system with timing adjustments to master timer for SAM detection errors

Disk drives are described in which the conventional write-to-read gap is omitted in selected sectors which frees up space that can be used for other purposes including writing a higher number of bits in the user data area in the gapless selected sectors. Alternative embodiments can use the additional space for servo information such as a repeatable run out (RRO) field. Conventional servo sector SID formats can be used for both gapped and gapless SIDs, which means that during seeking and reading operations full SIDs can be read for every wedge. The tradeoff for being able to write data much closer to the gapless SIDs is that the servo system does not detect the SAM or read the TID in the gapless SIDs during write operations.

Disk drive with a subset of sectors with reduced write-to-read gap

A method for repairing at least one defective servo segment of a servo sector having at least one defective servo track written on a magnetic recording media. The method comprises mapping the magnetic recording media for locations of the defective servo segment of the servo sector. A non-defective segment of the servo sector is replicated at least once on the magnetic recording media in a customer data zone, thereby creating at least one good servo segment copy of the servo sector. The good servo segment copy is propagated through the customer data zone associated with the defective servo segment. The good servo segment copy is copied onto the magnetic recording media previously occupied by the defective servo segment of the servo sector.

Repair of defective servo tracks

A method according to one embodiment comprises detecting a change in a rotational velocity of a magnetic disk or a spindle coupled to the magnetic disk, the change being caused by head-disk contact. A method for detecting head-disk contact according to another embodiment comprises measuring a rotational velocity of a magnetic disk or a spindle coupled to the magnetic disk; detecting a change in the rotational velocity, the change being caused by head-disk contact; and correlating the change in rotational velocity with the head-disk contact.

Method and system for detecting a change in a rotational velocity of a magnetic disk or a spindle coupled to the magnetic disk

Growing community of inventors

San Jose, CA, United States of America

Gary Allan Herbst