Distinct Servo Sector Patents (Class 360/77.08)
  • Patent number: 10297280
    Abstract: A method according to one embodiment includes generating a y-position estimate based on a servo readback signal from a servo reader reading a servo band, retrieving or calculating a nonlinearity-correction value corresponding to the y-position estimate, adjusting the y-position estimate using the nonlinearity-correction value, and outputting the adjusted y-position estimate. A computer program product for compensating for nonlinearity in a timing based servo pattern according to one embodiment includes a computer readable storage medium having program instructions embodied therewith. The computer readable storage medium is not a transitory signal per se. The program instructions are readable and/or executable by a controller to cause the controller to perform the foregoing method.
    Type: Grant
    Filed: July 24, 2018
    Date of Patent: May 21, 2019
    Assignee: International Business Machines Corporation
    Inventors: Kevin B. Judd, Simeon Furrer, Angeliki Pantazi, Mark A. Lantz
  • Patent number: 10249338
    Abstract: The disclosed technology provides a method that improves SMR throughput in vibration in storage systems. In one implementation, the method comprises receiving a write command to write data on a first track in a band of a storage medium, performing a vibration detection scheme to identify vibration events, determining if a number of vibration events is above a predetermined threshold, skipping the first track responsive to determining the number of vibration events is above a predetermined threshold, seeking to a second track adjacent to the first track, increasing an OCLIM on the second track adjacent to the first track from a default OCLIM to an increased OCLIM, and shifting the writer center on the second track adjacent to the first track.
    Type: Grant
    Filed: April 13, 2018
    Date of Patent: April 2, 2019
    Assignee: SEAGATE TECHNOLOGY, LLC
    Inventors: Jian Qiang, Xiong Liu
  • Patent number: 10152999
    Abstract: A data processing system is disclosed including a data detector, a data decoder and an alignment detector. The data detector is operable to apply a data detection algorithm to generate detected values for a data sector. The data decoder is operable to apply a data decode algorithm to a decoder input derived from the detected values to yield decoded values. The alignment detector is operable to calculate an offset between multiple versions of the data sector by correlating the multiple versions.
    Type: Grant
    Filed: July 26, 2013
    Date of Patent: December 11, 2018
    Assignee: Avago Technologies International Sales Pte. Limited
    Inventors: Shaohua Yang, George Mathew, Jefferson E. Singleton, Jongseung Park, Richard Rauschmayer
  • Patent number: 9972349
    Abstract: A data storage device is disclosed comprising a head actuated over a disk surface comprising a plurality of servo tracks, wherein the head comprises at least two read elements including a first read element and a second read element, and at least two of the read elements are offset radially relative to a center of the two read elements by at least a width of a servo track at all radial locations of the head over the disk surface. First servo data recorded in a first servo track is read using the first read element to generate a first read signal, and second servo data recorded in a second servo track is read using the second read element to generate a second read signal. The head is servoed over the disk surface based on at least the first read signal and the second read signal.
    Type: Grant
    Filed: August 30, 2017
    Date of Patent: May 15, 2018
    Assignee: Western Digital Technologies, Inc.
    Inventor: James B. French, Jr.
  • Patent number: 9875762
    Abstract: A storage device includes read circuitry having a read head having a detector that outputs signals representing data from a first track and an adjacent track. The read head is subject to off-track excursions during which the read head detects signals from both the first track and an adjacent track. Data on each track includes a preamble including a repeating pattern. The repeating pattern in any first track is orthogonal to the repeating pattern in any track adjacent to the first track. The read circuitry also includes respective Discrete Fourier Transform circuits to identify components in the signals corresponding to respective frequencies characteristic of the repeating pattern on the first track and the repeating pattern on the second track, and computation circuitry to determine from the components a ratio by which the read head is off-track. Corresponding methods are provided for operating such a storage device and for reading data.
    Type: Grant
    Filed: July 20, 2016
    Date of Patent: January 23, 2018
    Assignee: Marvell World Trade Ltd.
    Inventor: Nitin Nangare
  • Patent number: 9824708
    Abstract: A reference spiral is written on a recording surface of a hard disk drive. By launching writing of fine guide spirals from a launch point that is disposed on a pre-existing coarse guide spiral, writing of the fine guide spiral can be launched in response to a write head crossing the pre-existing coarse guide spiral, rather than in response to a precisely timed event. To enable launch points being disposed on pre-existing coarse guide spirals, launch points are not all located at the same radial position on the recording surface.
    Type: Grant
    Filed: March 31, 2015
    Date of Patent: November 21, 2017
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Jiangang Liang, Gabor Szita, Tony Huang, Gary W. Calfee
  • Patent number: 9799360
    Abstract: According to one embodiment, a magnetic disk drive in the present embodiment includes a disk including tracks, each including servo sectors, a head, and a controller configured to acquire first correction data for repeatable runout occurring in a first direction, and second correction data different from the first correction data, to write the first correction data within a first permitted range in the first direction, to write the second correction data within a write permitted range including the first permitted range and a second permitted range in a second direction opposite to the first direction, to read at least one of the first correction data and the second correction data, and to correctly place the head.
    Type: Grant
    Filed: September 16, 2016
    Date of Patent: October 24, 2017
    Assignee: Kabushiki Kaisha Toshiba
    Inventor: Naoki Tagami
  • Patent number: 9734853
    Abstract: An output is generated in response to an indication associated with movement of a moveable part in a storage device. The output is for reducing a noise component associated with the movement of the moveable part.
    Type: Grant
    Filed: May 2, 2011
    Date of Patent: August 15, 2017
    Assignee: Hewlett Packard Enterprise Development LP
    Inventors: Donald J. Fasen, Martin J. Harper
  • Patent number: 9633676
    Abstract: A magnetic storage medium is formed of magnetic nanoparticles that are encapsulated within nanotubes (e.g., carbon nanotubes).
    Type: Grant
    Filed: May 12, 2015
    Date of Patent: April 25, 2017
    Assignee: Gula Consulting Limited Liability Company
    Inventor: Tyson York Winarski
  • Patent number: 9508370
    Abstract: Method and apparatus for controlling the position of a control object in a closed loop control system, such as a servo control system used in a data storage device. In some embodiments, spaced apart first and second data tracks are written to a rotatable data recording medium without using repeated runout (RRO) compensation values to correct for RRO error in servo data written to the medium. A third data track is subsequently written so as to be interspersed between and partially overlap the first and second data tracks. The third data track is written using a set of RRO compensation values to correct for the RRO error in the servo data.
    Type: Grant
    Filed: May 26, 2016
    Date of Patent: November 29, 2016
    Assignee: Seagate Technology LLC
    Inventors: Wenzhong Zhu, Peter S. Harllee, Ralph William Cross, Kenneth A. Haapala, Edward Charles Gage
  • Patent number: 9471221
    Abstract: Implementations described and claimed herein provide a method and system for managing execution of commands for a storage device, the method comprising determining a plurality of commands to be executed for the storage device and while a storage device is executing at least one command, determining an execution order for at least two of the plurality of commands. Alternate implementation described and claimed herein provide a computer readable memory for storing a data structure, the data structure comprising a cost table comprising a number of cells, each cell containing one or more cost values related to one of a plurality of traversals between two locations on a storage device wherein each of the plurality of traversals is related to completion of one of a plurality of commands and a benefit array comprising a number of cells, each cell containing a benefit value related to completion of one of the plurality of commands.
    Type: Grant
    Filed: April 6, 2011
    Date of Patent: October 18, 2016
    Assignee: SEAGATE TECHNOLOGY LLC
    Inventors: Jonathan W. Haines, Timothy R. Feldman
  • Patent number: 9361920
    Abstract: An offset from track center of data is determined in a data storage device. The data is written to a heat-assisted magnetic recording medium of the device, and the offset compensates for degradation of an optical component of a read/write head when writing the data. The offset is stored in a memory of the storage device. Using the offset, a track alignment is changed during subsequent writes via the read/write head.
    Type: Grant
    Filed: February 19, 2015
    Date of Patent: June 7, 2016
    Assignee: SEAGATE TECHNOLOGY LLC
    Inventors: Wenzhong Zhu, Franklin P. Martens, Alfredo Sam Chu, Kaizhong Gao, Edward Charles Gage
  • Patent number: 9330701
    Abstract: Systems and methods are disclosed for using track misregistration values, representing an amount of off-track deviation of a write element, to dynamically increment error scan counters for proximate storage areas. In certain embodiments, an apparatus may comprise a processor configured to perform a write operation to record data to a target track of a data storage medium using a write element, determine an amount of deviation of the write element from a center line of the target track, and increment an error scan counter for an area of the data storage medium proximate to the target track based on the amount of deviation.
    Type: Grant
    Filed: December 15, 2014
    Date of Patent: May 3, 2016
    Assignee: Seagate Technology LLC
    Inventors: Richard P Michel, Joshua W Christensen
  • Patent number: 9305582
    Abstract: Various embodiments of the present invention provide systems and methods for determining changes in fly-height. For example, various embodiments of the present invention provide storage devices that include a storage medium having servo data thereon. A read/write head assembly is disposed in relation to the storage medium. A servo based fly-height adjustment circuit receives the servo data via the read/write head assembly, and calculates a first harmonics ratio based on the received data and compares the first harmonics ratio with a second harmonics ratio to determine an error in the distance between the read/write head assembly and the storage medium.
    Type: Grant
    Filed: October 27, 2008
    Date of Patent: April 5, 2016
    Assignee: Avago Technologies General IP (Singapore) Pte. Ltd.
    Inventors: George Mathew, Yuan Xing Lee, Hongwei Song, Jeffrey P. Grundvig, Viswanath Annampedu
  • Patent number: 9251835
    Abstract: A patterned magnetic media having offset servo and data regions. The media can be constructed by a method that allows both a data region and a servo region to be patterned without the patterning of one region adversely affecting the patterning of the other region. The method results in a patterned data region a patterned servo region and intermediate regions between the servo and data regions. The intermediate regions, which are most likely, but not necessarily, asymmetrical with one another indicate that the method has been used to pattern the media.
    Type: Grant
    Filed: June 4, 2013
    Date of Patent: February 2, 2016
    Assignee: HGST Netherlands B.V.
    Inventors: Michael K. Grobis, Jeffrey S. Lille, Ricardo Ruiz
  • Patent number: 9230584
    Abstract: According to one embodiment, a position demodulation apparatus is provided which demodulates a first demodulated signal and a second demodulated signal, based on a servo-pattern read signal read out by a head from a medium, acquires a plurality of sets of a vector length and phase angle of vectors on a phase plane denoting the first and second demodulated signals, detects a phase angle for which the vector length is greatest based on the sets acquired, and executes rotational correction using the difference between the detected phase angle and a particular reference angle as a correction amount.
    Type: Grant
    Filed: May 21, 2015
    Date of Patent: January 5, 2016
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Tatsuhiko Kosugi, Takuya Ogawa, Daisuke Sudo, Hideki Hironaka
  • Patent number: 9208813
    Abstract: Digital optical tape archival storage systems and methods are disclosed. A digital optical tape recorder may simultaneously write data and two or more guide tracks onto a digital optical tape recording medium. A digital optical taper reader may include a camera to capture a two-dimensional image of the digital optical tape recording medium, and an image processor to extract the data from the two-dimensional image.
    Type: Grant
    Filed: April 23, 2014
    Date of Patent: December 8, 2015
    Assignee: Group 47, Inc.
    Inventor: Daniel Scott Rosen
  • Patent number: 9159360
    Abstract: Disclosed is a technique of providing a perpendicular magnetic recording medium in which high-quality servo information enabling high-density recording of 500 kTPI or more is recorded, and a magnetic storage device of an adaptive track formatting type having large capacity, high reliability and high performance with high device manufacturing yield. At a servo area of the perpendicular magnetic recording medium, a servo sequence such as a burst pattern for positioning in a servo track is recorded in a seamless manner without big recording footprint (several times longer than the servo bit) and in a magnetization pattern such that a total amount of the recording magnetization is substantially zero.
    Type: Grant
    Filed: April 22, 2013
    Date of Patent: October 13, 2015
    Assignee: HITACHI, LTD.
    Inventor: Yoshihiro Shiroishi
  • Patent number: 9153264
    Abstract: A method of operating or calibrating a storage device having a storage medium platter includes writing servo data to the storage medium platter, where the servo data include, for each track on the storage medium platter, a servo sync mark, and a repeating pattern. For each pair of adjacent tracks on the storage medium platter, the repeating patterns, which may be orthogonal, are compared to determine relative phase of the repeating patterns on adjacent tracks. The relative phase for each pair of adjacent tracks is recorded. In another calibration method, first and second repeating patterns may compared to determine whether relative phase of the first and second repeating patterns exceeds a threshold, in which case the second servo data are erased, new second servo data are written, and the comparing and erasing are repeated until the relative phase of the first and second repeating patterns is less than the threshold.
    Type: Grant
    Filed: December 8, 2014
    Date of Patent: October 6, 2015
    Assignee: Marvell International Ltd.
    Inventors: Mats Oberg, Richard Travis Behrens
  • Patent number: 9123369
    Abstract: Determining the radial position of a first read head of a storage device includes reading servo data from a storage media platter surface using the first read head, deriving from that servo data a first positron error signal representing a first estimate of the radial position of the first read head, reading the servo data from the storage media platter surface using a different read head, deriving from that servo data a second position error signal representing an estimate of the radial position of the different read head, and combining the first estimate of the radial position of the first read head and the estimate of the radial position of the different read head to obtain a revised estimate of the radial position of the first read head. The combining could include taking account of a known positional offset between the first read head and the different read head.
    Type: Grant
    Filed: September 10, 2014
    Date of Patent: September 1, 2015
    Assignee: Marvell World Trade Ltd.
    Inventors: Mats Oberg, Qiyue Zou, Gregory Burd
  • Patent number: 9117471
    Abstract: An apparatus includes a controller configured to be coupled to a read/write head. The controller is configured to perform various operations including detecting a change in a time interval difference between servo sectors of a servo marked recording medium, converting the change to an offset signal that compensates for the change, and positioning the read/write head relative to the servo mark recording medium in response to the offset signal. The change in the time interval difference is representative of disk slip.
    Type: Grant
    Filed: December 19, 2014
    Date of Patent: August 25, 2015
    Assignee: SEAGATE TECHNOLOGY LLC
    Inventors: Xiong Liu, Mingzhong Ding, KianKeong Ooi, Hoang Dung Vu, Chan Fan Lau, Xiang Lu
  • Patent number: 9105289
    Abstract: A pattern of features of a storage medium includes first features having a first logical state and second features having a second logical state, wherein a cross track dimension of the first features is different from a cross track dimension of the second features. A transducer of a memory device senses the pattern of features and generates a transducer signal. Read circuitry samples the transducer signal at a frequency of a sampling clock signal and generates a read signal from the sampled transducer signal. Servo electronics includes a demodulator that demodulates at least first and second orthogonal frequency components of the read signal. Timing circuitry synchronizes a phase of the sampling clock signal with a phase of the pattern of features using the first orthogonal frequency component. Position error circuitry generates a signal indicating a cross track positional offset of the transducer relative to the features using the first and second orthogonal frequency components.
    Type: Grant
    Filed: October 15, 2014
    Date of Patent: August 11, 2015
    Assignee: SEAGATE TECHNOLOGY LLC
    Inventor: Bruce Douglas Buch
  • Patent number: 9099135
    Abstract: Methods including determining a distribution of a position error signal (PES) of a magnetoresistive head by obtaining PES data from a servo controller associated with the magnetoresistive head; determining an encroachment function of a storage disc; and determining a track density of the storage disc by considering both the PES distribution and the encroachment function.
    Type: Grant
    Filed: March 11, 2015
    Date of Patent: August 4, 2015
    Assignee: Seagate Technology LLC
    Inventors: HaoJi Bao, Aigang Feng, Myint Ngwe
  • Patent number: 9087541
    Abstract: Servo data of one or more tracks of a disk are collected using first and second read transducers co-located on a slider. Redundant portions of the servo data collected by the first and second read transducers are compared, and at least part of the servo data validating or corrected based on comparing the redundant portions.
    Type: Grant
    Filed: June 5, 2014
    Date of Patent: July 21, 2015
    Assignee: SEAGATE TECHNOLOGY LLC
    Inventors: Puskal Prasad Pokharel, Riyan Mendonsa
  • Patent number: 9082422
    Abstract: A magnetic head includes a main pole, a write shield, and first and second nonmagnetic layers. The main pole has a top surface including an inclined surface portion. The write shield includes an inclined portion facing toward the top surface of the main pole. The first nonmagnetic layer is interposed between the inclined surface portion and the inclined portion. The second nonmagnetic layer is interposed between the first nonmagnetic layer and the inclined portion. The first nonmagnetic layer has a first front end located in a medium facing surface. The second nonmagnetic layer has a second front end that is located closest to but at a distance from the medium facing surface.
    Type: Grant
    Filed: December 16, 2013
    Date of Patent: July 14, 2015
    Assignees: HEADWAY TECHNOLOGIES, INC., SAE MAGNETICS (H.K.) LTD.
    Inventors: Yoshitaka Sasaki, Hiroyuki Ito, Kazuki Sato, Shigeki Tanemura, Yukinori Ikegawa, Hironori Araki, Tatsuya Shimizu
  • Patent number: 9076465
    Abstract: A magnetic head includes a coil, a main pole, a write shield, a first insulating film, and a second insulating film. The coil includes a specific coil element. The main pole has a top surface including an inclined surface portion and a flat surface portion. The write shield includes an inclined portion. The inclined portion includes a first portion opposed to the inclined surface portion, and a second portion located farther from a medium facing surface than the first portion. The specific coil element includes an interposition part interposed between the flat surface portion and the second portion. The first insulating film is interposed between the inclined surface portion and the first portion of the inclined portion, and between the interposition part and the second portion of the inclined portion. The second insulating film is interposed between the first insulating film and the second portion of the inclined portion.
    Type: Grant
    Filed: December 16, 2013
    Date of Patent: July 7, 2015
    Assignees: HEADWAY TECHNOLOGIES, INC., SAE MAGNETICS (H.K.) LTD.
    Inventors: Yoshitaka Sasaki, Hiroyuki Ito, Kazuki Sato, Shigeki Tanemura, Yukinori Ikegawa, Hironori Araki, Tatsuya Shimizu
  • Patent number: 9070410
    Abstract: According to various embodiments, a recording medium may be provided. The recording medium may include a dedicated servo layer configured to provide servo information. The dedicated servo layer may include a plurality of tracks. A first track may include a first servo signal. The first servo signal may include first servo bursts of a pre-determined frequency. A second track adjacent to the first track may include a second servo signal. The second servo signal may include second servo bursts of the pre-determined frequency.
    Type: Grant
    Filed: July 19, 2013
    Date of Patent: June 30, 2015
    Assignee: MARVELL INTERNATIONAL LTD.
    Inventors: Jingliang Zhang, Anmin Kong, Songhua Zhang, Zhimin Yuan, Linlin Thi
  • Patent number: 9042045
    Abstract: A disk drive is disclosed including a disk having a plurality of sectors, and a head actuated over the disk. A defect threshold is initialized, and a first sector is read to generate a first read signal. The first read signal is processed to detect a defect in the first sector relative to the defect threshold. After detecting the defect, the defect threshold is adjusted and the first sector is reread to generate a second read signal. The second read signal is processed to detect the defect in the first sector relative to the adjusted defect threshold.
    Type: Grant
    Filed: November 1, 2007
    Date of Patent: May 26, 2015
    Assignee: Western Digital Technologies, Inc.
    Inventors: Dean V. Dang, Kek Ming Chua, King S. Goh, Prakash Balasubramaniam, Ming Jin
  • Patent number: 9019652
    Abstract: According to one embodiment, a head position demodulating method and a magnetic disk device switch a demodulation window such that an amplitude of a fundamental wave component of a null-type burst pattern transitions from a decreasing direction to an increasing direction along with an increase in seek speed during demodulation of the null-type burst pattern recorded on a magnetic disk.
    Type: Grant
    Filed: February 11, 2014
    Date of Patent: April 28, 2015
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Tatsuhiko Kosugi, Kazunori Mori, Hiroshi Ooyabu
  • Publication number: 20150103435
    Abstract: According to one embodiment, a head position demodulating method and a magnetic disk device switch a demodulation window such that an amplitude of a fundamental wave component of a null-type burst pattern transitions from a decreasing direction to an increasing direction along with an increase in seek speed during demodulation of the null-type burst pattern recorded on a magnetic disk.
    Type: Application
    Filed: February 11, 2014
    Publication date: April 16, 2015
    Applicant: KABUSHIKI KAISHA TOSHIBA
    Inventors: Tatsuhiko KOSUGI, Kazunori MORI, Hiroshi OOYABU
  • Patent number: 9001454
    Abstract: A disk drive is disclosed comprising a disk comprising tracks defined by servo sectors, a head, and control circuitry comprising a servo control system operable to actuate the head over the disk in response to the servo sectors. The servo control system is configured into a first state, and a position error signal (PES) representing a difference between a target location for the head and a measured location for the head is generated. An actuator control signal is generated in response to the PES, a feed-forward control signal is adapted in response to the servo sectors, and the actuator control signal is adjusted using the feed-forward control signal. The servo control system is configured from the first state to a second state, and a phase of the adaptation of the feed-forward control signal is adjusted based on the second state.
    Type: Grant
    Filed: April 12, 2013
    Date of Patent: April 7, 2015
    Inventors: Young-Hoon Kim, Wei Xi
  • Patent number: 8995075
    Abstract: A disk drive is disclosed comprising a disk comprising a plurality of servo sectors defining a plurality of servo tracks. The servo tracks form a plurality of servo zones, where a servo data rate of servo sectors in a first servo zone is different than a servo data rate of servo sectors in a second servo zone. A servo control system servos a head over the disk. An estimated servo state of a servo control system is generated, and when the head crosses from a first servo zone to a second servo zone, the estimated servo state is adjusted to compensate for a transient in a circumferential distance between a servo sector in the first servo zone and a servo sector in the second servo zone.
    Type: Grant
    Filed: June 21, 2012
    Date of Patent: March 31, 2015
    Assignee: Western Digital Technologies, Inc.
    Inventors: Michael Chang, Guoxiao Guo, Jie Yu
  • Patent number: 8982505
    Abstract: According to one embodiment, there is provided a method for generating address data. The method generates a first code corresponding to a cylinder number. The cylinder number is divided and recorded on servo sectors in association with an identification of a cylinder on a disk. The first code is formed of some codes obtained by dividing the cylinder number based on a number of each of the servo sectors. The method generates a second code corresponding to address data for each of the servo sectors, by encoding the first code based on the servo sector number and a servo format number. The servo format number is used to identify a format of each of the servo sectors.
    Type: Grant
    Filed: November 5, 2013
    Date of Patent: March 17, 2015
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Takayuki Kawabe, Takeyori Hara
  • Patent number: 8970981
    Abstract: A hard disk drive uses a second, reference burst field in a preamble to estimate burst phase and burst magnitude. Such estimations are used for position error signal integration and repeatable runout correction. Gain error is also derived from such estimations. Information contained in a preamble field is used in conjunction with the reference burst phase estimation to synchronize servo address marks.
    Type: Grant
    Filed: March 27, 2013
    Date of Patent: March 3, 2015
    Assignee: LSI Corporation
    Inventors: Xun Zhang, Haitao Xia, Dahua Qin
  • Patent number: 8964325
    Abstract: A magnetic disk device according to an embodiment includes a head and a disk with a recording surface, the head including a reader configured to perform data reading, and a writer configured to write data. A method of correcting a read/write offset, according to the embodiment, is applied to the above magnetic disk device. This method includes reconstructing position data read by the reader, using a spline function, and correcting a read/write offset due to the distance between the writer and the reader, using the reconstructed position data.
    Type: Grant
    Filed: March 5, 2014
    Date of Patent: February 24, 2015
    Assignee: Kabushiki Kaisha Toshiba
    Inventor: Tomoyoshi Yamada
  • Patent number: 8953279
    Abstract: At least three servo burst frequencies are simultaneously detected during a rotation of a disk using a read head. A position of the read head during the rotation is determined based on simultaneously reading at least two of the at least three servo burst frequencies.
    Type: Grant
    Filed: March 21, 2014
    Date of Patent: February 10, 2015
    Assignee: Seagate Technology LLC
    Inventors: Riyan Mendonsa, Puskal Prasad Pokharel
  • Patent number: 8947821
    Abstract: According to one embodiment, a system for processing data includes an equalizer configured to use servo coefficients for processing servo data and data coefficients for processing non-servo data, wherein the equalizer includes a finite impulse response (FIR) filter configured to process data read with a magnetic tape channel using the servo coefficients to generate equalized data, one or more low-pass filters with aggressive frequency characteristics configured to filter the equalized data to output filtered data, the one or more low-pass filters with aggressive frequency characteristics being configured to remove high frequency noise from the equalized data, a peak detector configured to process peaks in a waveform of the filtered data, and at least one servo pattern detector configured to detect a servo pattern in the filtered data. Other systems and methods for processing data are described in more embodiments.
    Type: Grant
    Filed: July 17, 2014
    Date of Patent: February 3, 2015
    Assignee: International Business Machines Corporation
    Inventors: Katherine T. Blinick, Giovanni Cherubini, Robert A. Hutchins, Jens Jelitto
  • Patent number: 8947809
    Abstract: A bit patterned media (BPM) encoded recordable medium includes a servo control field including servo bits. Each servo bit is represented by a servo bit pattern of dots and gaps on the recordable medium. In the servo bit patterns, substantially no two dots are placed immediately next to one another, and substantially all servo bit patterns start with a gap and/or substantially all servo bit patterns end with a gap.
    Type: Grant
    Filed: September 19, 2008
    Date of Patent: February 3, 2015
    Assignee: Seagate Technology LLC
    Inventors: Mustafa Can Ozturk, Puskal Prasad Pokharel
  • Patent number: 8947810
    Abstract: Techniques are provided for performing bit-locked operations on media. A first control signal is received from a first source, and a second control signal is generated at a second source in response to receiving the first control signal. The media is accessed according to the second control signal. One or more synchronization markers are located during the accessing of the media, and bit-level synchronization between the second source and the media is achieved based, at least partially, on the one or more synchronization markers. A control operation is performed on the media with bit-level synchrony between the second source and the media.
    Type: Grant
    Filed: March 10, 2014
    Date of Patent: February 3, 2015
    Assignee: Marvell International Ltd.
    Inventors: Gregory Burd, Qiyue Zou, Michael Madden, Kar Shing Chiu, Vincent Wong
  • Patent number: 8922931
    Abstract: A disk drive is disclosed wherein N data wedges of write data are buffered in a buffer. After writing at least two of the data wedges to the disk including a first data wedge and a second data wedge, a first servo metric value is measured when reading a first servo sector, and a second servo metric value is predicted based on the first servo metric value, wherein the second servo metric value corresponds to a second servo sector following the first servo sector. When the first servo metric value indicates a safe write condition and the second servo metric value indicates an unsafe write condition, the first data wedge is released from the buffer, and when the first servo metric value indicates a safe write condition and the second servo metric value indicates a safe write condition, the first and second data wedges are released from the buffer.
    Type: Grant
    Filed: June 26, 2013
    Date of Patent: December 30, 2014
    Assignee: Western Digital Technologies, Inc.
    Inventors: Chuanwen Ji, Alain Chahwan, Orhan Beker, Yanan Huang, Duc T. Phan
  • Patent number: 8922921
    Abstract: A first portion of a track identifier is read from a first servo wedge of a track of a magnetic disk. A second portion of the track identifier is read from a second servo wedge of the track. The second portion includes least-significant bits of the track identifier that are also stored in the first portion. The first and second portions are combined to determine the track identifier for the first and second servo wedges, and the track is identified using the track identifier.
    Type: Grant
    Filed: November 5, 2013
    Date of Patent: December 30, 2014
    Assignee: Seagate Technology LLC
    Inventors: Ravi Hebbar, Russel Clemmons, Bruce D. Buch
  • Patent number: 8917475
    Abstract: A disk drive is disclosed comprising a disk comprising servo data, and a head actuated over the disk. An offset r0 representing a difference between an axial rotation of the disk and an axial rotation of the servo data is estimated, and radial dependent timing compensation values are generated in response to the estimated r0. A phase error is generated in response to the servo data, and a control signal is generated in response to the phase error and the radial dependent timing compensation values. A frequency of an oscillator is adjusted in response to the control signal.
    Type: Grant
    Filed: December 20, 2013
    Date of Patent: December 23, 2014
    Assignee: Western Digital Technologies, Inc.
    Inventors: Yuanyuan Zhao, Wei Xi
  • Patent number: 8908309
    Abstract: A system, method, and apparatus for forming a high quality master pattern for patterned media, including features to support servo patterns, is disclosed. Block copolymer self-assembly is used to facilitate the formation of a track pattern with narrower tracks. E-beam lithography forms a chemical contrast pattern of concentric rings, where the spacing of the rings is equal to an integral multiple of the target track pitch. The rings include regions within each servo sector header where the rings are offset radially by a fraction of a track pitch. Self-assembly is performed to form a new ring pattern at the target track pitch on top of the chemical contrast pattern, including the radial offsets in the servo sector headers. When this pattern is transferred to disks via nanoimprinting and etching, it creates tracks separated by nonmagnetic grooves, with the grooves and tracks including the radial offset regions.
    Type: Grant
    Filed: May 31, 2013
    Date of Patent: December 9, 2014
    Assignee: HGST Netherlands B.V.
    Inventors: Thomas Robert Albrecht, Bruno Marchon, Ricardo Ruiz
  • Patent number: 8908303
    Abstract: According to one embodiment, in a method for servo demodulation, a first demodulated signal and a second demodulated signal, which are calculated from amplitude values of burst signal patterns of a first area and a second area, are generated in order to generate a position error signal of a reader, based on a servo pattern read from a disk by the reader. Further, in the method for servo demodulation, a square-root of sum of squares of the first and the second demodulated signals is calculated, and an optimal compensation coefficient of a linearity correction function to be used in linearity compensation of the position error signal is calculated based on a maximum value and a minimum value of the square-root of sum of squares.
    Type: Grant
    Filed: November 15, 2013
    Date of Patent: December 9, 2014
    Assignee: Kabushiki Kaisha Toshiba
    Inventor: Tomoyoshi Yamada
  • Patent number: 8902535
    Abstract: A disk drive is disclosed comprising a head actuated over a disk comprising servo information. A position error signal is generated while executing a first plurality of seek operations to seek the head over a seek length, and first feed-forward compensation values are adapted for a first segment of the seek length using an iterative learning control algorithm based on the position error signal. During a second plurality of seeks, second feed-forward compensation values are adapted for a second segment of the seek length using the iterative learning control algorithm based on the position error signal. The servo control system is operable to execute the second plurality of seek operations using the first feed-forward compensation generated for the first segment of the seek length.
    Type: Grant
    Filed: December 12, 2012
    Date of Patent: December 2, 2014
    Assignee: Western Digital Technologies, Inc.
    Inventors: Jianbin Nie, Edgar D. Sheh, Siri S. Weerasooriya
  • Patent number: 8891194
    Abstract: A disk drive is disclosed comprising a head actuated over a disk. A position y of the head is measured based on servo sectors, and the measured position y of the head is adjusted based on: z1=y+c1(y) where z1 represents a first adjusted position and c1(y) represents first correction values. The first adjusted position z1 is adjusted based on: z2=z1+c2(z1) where z2 represents a second adjusted position and c2(z1) represents second correction values. The first and second correction values are combined based on: c3(y)=c1(y)+c2(y+c1(y)). The measured position y of the head is adjusted based on: z3=y+c3(y) where z3 represents a third adjusted position comprising the adjustment based on c1(y) and the adjustment based on c2(y), and c3(y) represents third correction values.
    Type: Grant
    Filed: June 20, 2013
    Date of Patent: November 18, 2014
    Assignee: Western Digital Technologies, Inc.
    Inventors: Sanghoon Chu, Richard K. Wong, Min Chen
  • Patent number: 8885286
    Abstract: A magnetic disk device includes a magnetic disk, a head and a control section. The head writes data to the magnetic disk. The control section controls the head to move along a virtual circular orbit of the magnetic disk that includes a first servo sector region and a second servo sector region. The second servo sector region has a larger servo interval than the first servo sector region, and stores a larger number of write bits than the first servo sector region.
    Type: Grant
    Filed: August 22, 2013
    Date of Patent: November 11, 2014
    Assignee: Kabushiki Kaisha Toshiba
    Inventor: Koji Ishii
  • Patent number: 8867162
    Abstract: According to one embodiment, a magnetic head, a magnetic disk and a magnetic recording controller are provided. The magnetic disk has a burst pattern recorded thereon for determining a position of the magnetic head on a track based on a reading result by the magnetic head. The magnetic recording controller corrects a demodulation position of the magnetic head based on an offset correction value subject to fluctuation of the burst pattern.
    Type: Grant
    Filed: February 4, 2013
    Date of Patent: October 21, 2014
    Assignee: Kabushiki Kaisha Toshiba
    Inventor: Daisuke Sudo
  • Patent number: 8854761
    Abstract: A method of writing servo data to a data storage medium includes reading a servo instruction from a memory, the servo instruction comprising a control portion and a data portion, processing the servo instruction in a controller to generate a servo data pattern from the data portion based on the control portion, and transferring the servo data pattern to the data storage medium. The processing may include transforming the data portion into the servo data pattern based on the control portion. The processing also may include following a command in the control portion to use the data portion as an index to retrieve a pre-programmed servo data pattern from a pattern store. The transferring may include storing the servo data pattern in a buffer, and writing the servo data pattern from the buffer to the data storage medium.
    Type: Grant
    Filed: September 30, 2013
    Date of Patent: October 7, 2014
    Assignee: Marvell International Ltd.
    Inventors: Supaket Katchmart, David Liaw
  • Patent number: 8824079
    Abstract: A servo control field on a recordable medium includes a bit patterned media (BPM) pattern including a plurality of dots arranged in a down-track orientation and in a cross-track orientation, wherein the dots comprise a plurality of dot composites. Each of the dot composites includes a plurality of dots. A first spacing between adjacent ones of the plurality of dots in a dot composite in the down-track direction on the recordable medium is less than a second spacing between adjacent ones of the plurality of dot composites in the down-track direction. A readback signal generated in response to the BPM patterned may be filtered to attenuate harmonic frequencies in the readback signal.
    Type: Grant
    Filed: December 17, 2008
    Date of Patent: September 2, 2014
    Assignee: Seagate Technology LLC
    Inventors: Puskal Prasad Pokharel, Mustafa Can Ozturk