By Memory Storage Of Repeatable Error Or Correction Patents (Class 360/77.04)
  • Patent number: 10366717
    Abstract: According to one embodiment a magnetic disk device, includes a disk which includes a plurality of servo sectors radially extending in a radial direction and being discretely disposed with a gap in a circumferential direction, a head which writes data to the disk and reads data from the disk, and a controller which writes a plurality of pieces of correction data with respect to a repeatable run-out of the disk to a plurality of first sectors disposed between the servo sectors in a first region, and writes the pieces of correction data to a plurality of second sectors disposed between the servo sectors in a second region different from the first region.
    Type: Grant
    Filed: September 12, 2018
    Date of Patent: July 30, 2019
    Assignees: Kabushiki Kaisha Toshiba, Toshiba Electronics Devices & Storage Corporation
    Inventor: Fumiya Kudo
  • Patent number: 10176849
    Abstract: The disclosed technology includes methods and systems that reduce off-track write retry operations in shingled magnetic recording systems. In one implementation, the method includes writing data to an initial track, determining which side of the initial track is a shingled side, calculating a percentage of position error signal (PES) at a shingled side end of the initial track (PES1) when an off-track write operation occurs, determining whether the PES1 meets a first pre-determined threshold, continue writing data to a second track responsive to determining the PES1 is below a first pre-determined threshold, calculating a percentage of PES at a shingled side end of the second track (PES2), determining whether a combined value of PES1 and PES2 is above a second predetermined threshold to determine a probability value of the initial track being erased, and continue writing to a third track if the combined value is below the second predetermined threshold.
    Type: Grant
    Filed: September 29, 2017
    Date of Patent: January 8, 2019
    Assignee: SEAGATE TECHNOLOGY LLC
    Inventors: Jian Qiang, Xiong Liu, Choon Wei Ng, Sangyun Jung
  • Patent number: 10162393
    Abstract: As may be implemented in accordance with one or more embodiments, an electrical connector such as a low-temperature co-fired ceramic (LTCC) connector is sealed to an opening in a base deck having bottom and/or side walls that define a cavity. A mechanical component is coupled to balance forces applied to opposing surfaces of the electrical connector, which can mitigate the application of high forces to connector pins and/or to the connector itself. Further, this balancing may be implemented to maintain a controlled bias force against the connector. The electrical connector may, for example, be hermetically sealed to the opening by a seal such as a gasket, epoxy or other material, which may be included in the electrical connector.
    Type: Grant
    Filed: January 13, 2016
    Date of Patent: December 25, 2018
    Assignee: Seagate Technology LLC
    Inventors: Tave Joseph Fruge, Frank William Bernett, John Francis Fletcher, Richard K. Thompson
  • Patent number: 10090009
    Abstract: An apparatus includes a disk locked clock system and a feedforward microactuator compensator. The disk locked clock system is configured to estimate a timing error and generate a timing error signal. The feedforward microactuator compensator is configured to generate a microactuator compensation signal, without use of a vibration sensor signal, in response to the timing error signal.
    Type: Grant
    Filed: August 25, 2016
    Date of Patent: October 2, 2018
    Assignee: Seagate Technology LLC
    Inventors: Qiang Bi, GuoQing Zhang, Kian Keong Ooi, MingZhong Ding, WenJun Cao
  • Patent number: 10007237
    Abstract: Provided is a control device (1) for controlling a control target that comprises an inverse response system (2) having inverse response characteristics, i.e., in which the initial response rocks in the inverse direction from the input change direction. The control device (1) comprises an inverse response compensation system (5) that compensates for the inverse response characteristics in the control target. This inverse response compensation system (5) is configured to calculate a comparison value for the output of the control target and the output of a control target from which a portion or all of the unstable zeros have been removed and feed the calculated comparison value back to the input side of the control target.
    Type: Grant
    Filed: October 15, 2013
    Date of Patent: June 26, 2018
    Assignee: Kobe Steel, Ltd.
    Inventor: Yoshiharu Nishida
  • Patent number: 9997185
    Abstract: A data storage device comprising a head actuated over a disk comprising a plurality of tracks. The head is positioned over a target track, and a sampled position error signal (PES) is generated representing a position of the head relative to the target track. The sampled PES is filtered with a servo compensator to generate a sampled control signal, and the sampled control signal is upsampled to generate an upsampled control signal. The sampled PES is upsampled to generate an upsampled PES, and the upsampled PES is processed to generate compensation values. The upsampled control signal is combined with the compensation values to generate a compensated control signal, and the position of the head over the target track is adjusted based on the compensated control signal.
    Type: Grant
    Filed: November 20, 2017
    Date of Patent: June 12, 2018
    Assignee: Western Digital Technologies, Inc.
    Inventor: Hiroshi Uchida
  • Patent number: 9934805
    Abstract: According to one embodiment, a magnetic disk device including a disk, and a controller which calculates a first corrected value based on a first eccentricity of the disk, and writes a first track based on the first corrected value, wherein when the controller interrupts the process for writing the second track so as to overlap the first track at a first position, the controller measures a second eccentricity of the disk, and compares the first eccentricity with the second eccentricity, and when the first eccentricity is different from the second eccentricity, the controller restarts the process for writing the second track from a second position away from the first position in a radial direction.
    Type: Grant
    Filed: August 31, 2017
    Date of Patent: April 3, 2018
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Wataru Tsukahara, Shinichirou Kouhara, Takao Abe
  • Patent number: 9905257
    Abstract: A method for writing servo data includes writing servo data as a head moves outward on a disk one step at a time, so as to overwrite part of servo data that have been written in a previous step, writing servo data as the head moves inward on the disk one step at a time, so as to overwrite part of servo data that have been written in a previous step, and writing one of two-phase burst data, or address data and the other of said two-phase burst data, at the radial position, so as to overwrite at least part of servo data written in each last step of the writings as the head moves outward and inward. The same address data are written in two consecutive steps as the head moves outward and as the head moves inward.
    Type: Grant
    Filed: August 22, 2016
    Date of Patent: February 27, 2018
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Shinsuke Akiya, Kazuhiko Takaishi, Hideo Sado
  • Patent number: 9837114
    Abstract: A method for manufacturing a disk device includes the steps of measuring a first gain of a control signal of a fine motion actuator while positioning a head to a first radial position of a disk medium using a coarse motion actuator but not the fine motion actuator, based on an auxiliary servo pattern recorded on the disk medium, measuring a second gain of a control signal of the fine motion actuator while positioning the head to a second radial position of the disk medium using the coarse motion actuator but not the fine motion actuator, based on the auxiliary servo pattern recorded on the disk medium, and determining gain correction values which are to be applied to a control signal for the fine motion actuator while performing servo pattern writing on the disk medium, based on the first and second gains.
    Type: Grant
    Filed: March 3, 2017
    Date of Patent: December 5, 2017
    Assignee: Kabushiki Kaisha Toshiba
    Inventor: Kazuhiko Takaishi
  • Patent number: 9836040
    Abstract: A motor control device includes circuitry which reads a command value in synchronization with a control period, reads an output of an encoder connected to a motor, controls an output current to the motor based on the command value and the output of the encoder, and offsets a timing for reading the output of the encoder with respect to a timing for reading the command value.
    Type: Grant
    Filed: April 29, 2016
    Date of Patent: December 5, 2017
    Assignee: KABUSHIKI KAISHA YASKAWA DENKI
    Inventors: Tadashi Okubo, Isamu Matsumura, Go Yamazaki
  • Patent number: 9761271
    Abstract: A storage device includes a controller configured to adjusts direct offline scan (DOS) parameters for a scan of a storage region based on a workload affecting the storage region to mitigate data loss due to adjacent track interference (ATI) while also mitigating performance delays due to DOS execution. In one implementation, a type of workload occurring in a region is determined by assessing a distribution of write track counter values corresponding to data tracks in the region.
    Type: Grant
    Filed: August 1, 2016
    Date of Patent: September 12, 2017
    Assignee: SEAGATE TECHNOLOGY LLC
    Inventors: Michael D. Schaff, Abhay T. Kataria
  • Patent number: 9633689
    Abstract: An apparatus for storing data includes a storage medium with user data regions and with servo data regions containing preamble patterns. Servo data in the servo data regions is written with a varying clock frequency across the storage medium. The apparatus also includes a head assembly disposed in relation to the storage medium and operable to read and write data on the storage medium. The apparatus also includes a preamble detection circuit adapted to search an input stream derived from the head assembly for the preamble patterns in a number of frequency bins.
    Type: Grant
    Filed: January 19, 2016
    Date of Patent: April 25, 2017
    Assignee: AVAGO TECHNOLOGIES GENERAL IP (SINGAPORE) PTE. LTD.
    Inventors: Jeffrey P. Grundvig, Richard Rauschmayer
  • Patent number: 9590775
    Abstract: Uplink CoMP point selection is achieved, considering power consumption of a MTC device and uplink overhead. Two resource blocks of a first resource block containing a reference signal and a second resource block for transmitting user data are combined to achieve uplink CoMP. The time interval between these two resource blocks is a time of approximately several milliseconds to several tens milliseconds necessary that each eNodeB acquires reception quality to be collected to a Serving eNodeB via the X2 interface and analyze its content.
    Type: Grant
    Filed: December 26, 2012
    Date of Patent: March 7, 2017
    Assignee: SONY CORPORATION
    Inventor: Hiroaki Takano
  • Patent number: 9502062
    Abstract: First and second repeatable runout (ZAP) values are both located on a first virtual track of a magnetic disk. The first ZAP value is offset from the first virtual track center in a first direction and the second ZAP value is offset from the first virtual track center in a second direction opposite the first direction. At least one of the first and second ZAP values are accessed when performing repeatable runout correction for a writer of the read/write head that is being positioned over a second virtual track of the magnetic disk.
    Type: Grant
    Filed: October 30, 2015
    Date of Patent: November 22, 2016
    Assignee: SEAGATE TECHNOLOGY LLC
    Inventors: Andrei Dorobantu, Thomas C. Zirps, Tim Rausch
  • Patent number: 9459894
    Abstract: A method and structure for dynamic memory re-allocation for an application runtime environment (ARE) includes receiving, through an interface of an application runtime environment (ARE), a first set of internal operational metrics of the ARE executing at a current setting S1 on a processor of a computer. A first performance P1 of the ARE is determined at the current setting S1 using the received first set of internal operation metrics. The current setting S1 of the ARE is varied to a new setting S2. A second set of internal operational metrics of the ARE executing at the new setting S2 is received through the interface of the ARE. A second performance P2 of the ARE is determined at the new setting S2, using the received second set of internal operation metrics. A memory allocation for the ARE is re-allocated, based on the determined performances P1 and P2.
    Type: Grant
    Filed: June 17, 2014
    Date of Patent: October 4, 2016
    Assignee: International Business Machines Corporation
    Inventors: Norman Bobroff, Liana Liyow Fong, Peter Hans Westernick
  • Patent number: 9384778
    Abstract: Systems and methods for resource allocation for a large sector format processing may include, but are not limited to, operations for: determining non-convergence of a magnetic disc sub-sector of a first magnetic disc sector within a processing time frame allocated to the magnetic disc sub-sector; determining a convergence of a second magnetic disc sector occurring in less time than a processing time frame allocated to the second magnetic disc sector; and processing the magnetic disc sub-sector during a portion of the processing time frame allocated to the second magnetic disc sector remaining after processing of the second magnetic disc sector.
    Type: Grant
    Filed: May 2, 2014
    Date of Patent: July 5, 2016
    Assignee: Avago Technologies General IP (Singapore) Pte Ltd.
    Inventors: Shu Li, Fan Zhang, Jun Xiao
  • Patent number: 9349400
    Abstract: A hard disk drive with adjustable data track pitch has repeatable runout (RRO) fields stored in he servo sectors for each servo sector of each servo track, and thus without the need to store the RRO fields in the data tracks. The RRO fields for each servo sector have a radial length of at least two servo tracks (i.e., equal to or greater than twice the servo track pitch). The RRO fields in each servo track are shifted radially from RRO fields in adjacent servo tracks and circumferentially spaced from RRO fields in adjacent servo tracks. The read head reads two different RRO fields from the two servo tracks closest to the data track and the servo electronics interpolates a RRO value from these two RRO values. Thus even if the data track pitch is changed, RRO values can be obtained.
    Type: Grant
    Filed: June 25, 2015
    Date of Patent: May 24, 2016
    Assignee: HGST Netherlands B.V.
    Inventors: Abhishek Dhanda, Toshiki Hirano, Tetsuo Semba, Satoshi Yamamoto
  • Patent number: 9343094
    Abstract: A data storage device is disclosed comprising a head actuated over a disk comprising a plurality of servo tracks defined by servo bursts. A number of burst correction values are generated by reading at least one of the servo bursts at a number of different radial locations across the disk. The burst correction values are filtered to generate filtered burst correction values, and the filtered burst correction values are downsampled to generate downsampled burst correction values. The downsampled burst correction values are written to the disk, and the head is servoed over the disk by reading the downsampled burst correction values from the disk.
    Type: Grant
    Filed: March 26, 2015
    Date of Patent: May 17, 2016
    Assignee: Western Digital Technologies, Inc.
    Inventors: Kun Ma, Jianyi Wang, Hui Li, Wai Ee Wong, Guoxiao Guo
  • Patent number: 9324368
    Abstract: A data storage device with improved data storage densities, coupled with lower hard error and write-inhibit events is described. A feed-forward write inhibit (FFWI) method enables data tracks to be written more densely. Alternatively, the FFWI method may reduce the hard error and write inhibit events to improve data storage performance. A concept of virtual tracks enables the FFWI method to be applied to the writing of circular data tracks with non-circular servo tracks, or to the writing of non-circular data tracks with PES data from circular servo tracks—in both cases, improvements to performance and/or storage densities are enabled. The FFWI method may also be applied to the case of both non-circular servo and data tracks.
    Type: Grant
    Filed: January 5, 2015
    Date of Patent: April 26, 2016
    Assignee: HGST NETHERLANDS B.V.
    Inventors: Abhishek Dhanda, Toshiki Hirano, Tetsuo Semba
  • Patent number: 9311940
    Abstract: First and second position error signals (PES) are measured from respective first and second read heads that are simultaneously reading two different surfaces of a recording medium. A common repeatable runout (RRO) compensation signal and a differential RRO signal are determined based on the first and second PES. A voice coil motor that drives the first and second read heads is adjusted using the common RRO compensation signal, and first and second microactuators that respectively position the first and second read heads are adjusted based on the differential RRO signal.
    Type: Grant
    Filed: July 28, 2015
    Date of Patent: April 12, 2016
    Assignee: SEAGATE TECHNOLOGY LLC
    Inventors: Evgeny Kharisov, Kenneth Haapala
  • Patent number: 9286925
    Abstract: A data storage device is disclosed comprising a head actuated over a disk comprising a plurality of servo tracks defined by servo bursts. The head is positioned at a first radial location over the disk and a first burst correction value is generated by reading at least one of the servo bursts. The head is positioned at a second radial location over the disk and a second burst correction value is generated by reading at least one of the servo bursts. The head is positioned at a third radial location over the disk and the first burst correction value and the second burst correction value are written at the third radial location. The head is servoed over the disk by reading the first and second burst correction values.
    Type: Grant
    Filed: March 26, 2015
    Date of Patent: March 15, 2016
    Assignee: Western Digital Technologies, Inc.
    Inventors: Stanley H. Shepherd, Yakov M. Lifschitz, Min Chen, Guoxiao Guo, Jason Laks
  • Patent number: 9210437
    Abstract: A hardware multi-stream multi-standard video decoder device. A command parser accesses a plurality of video streams, identifies a video encoding standard used for encoding video streams of the plurality of video streams, and interleaves portions of the plurality of video streams. A plurality of hardware decoding blocks perform operations associated with decoding the plurality of video streams, wherein different subsets of the plurality of hardware decoding blocks are for decoding video streams encoded using different video encoding standards, such that interleaved video streams are decoded by activating subsets of the plurality of hardware decoding blocks for use in decoding the plurality of video streams. A plurality of register sets store parameters associated with the plurality of video streams.
    Type: Grant
    Filed: December 9, 2005
    Date of Patent: December 8, 2015
    Assignee: NVIDIA CORPORATION
    Inventors: Harikrishna M. Reddy, Ignatius B. Tjandrasuwita, Iole Moccagatta
  • Patent number: 9204158
    Abstract: A hardware multi-standard video decoder device. A command parser accesses a video stream and identifies a video encoding standard used for encoding the video stream. A plurality of hardware decoding blocks perform operations associated with decoding the video stream, wherein different subsets of the plurality of hardware decoding blocks are for decoding video streams encoded using different video encoding standards.
    Type: Grant
    Filed: December 9, 2005
    Date of Patent: December 1, 2015
    Assignee: NVIDIA CORPORATION
    Inventors: Ignatius B. Tjandrasuwita, Harikrishna M. Reddy, Iole Moccagatta
  • Patent number: 9190105
    Abstract: Radially-coherent data reading from, and data writing to, a magnetic disk use non-coherently written synchronization signals on the disk. In a form, the radially-coherent data reading and writing is performed using a magnetic head/disk tester which includes a spinstand for supporting a spinning magnetic disk, a magnetic head assembly, a write channel network for generating a write data signal for application to a write element of the magnetic head, a read channel for receiving a read-back signal from a read element of the magnetic head assembly, and a signal processing system that analyzes a read-back signal from a disk and provides synchronization signals for radially-coherent data reading and data writing.
    Type: Grant
    Filed: May 19, 2015
    Date of Patent: November 17, 2015
    Assignee: GUZIK TECHNICAL ENTERPRISES
    Inventor: Vladislav Klimov
  • Patent number: 9117489
    Abstract: A data storage device is disclosed comprising a head actuated over a disk comprising a plurality of tracks. A defect scan of at least one of the tracks is executed, and a log entry is generated when a defect is detected. After the defect scan, a verify operation is executed for at least two of the detected defects. A number of times the verify operation detects a false defect is counted, and whether the head is defective is determined based at least partly on the count.
    Type: Grant
    Filed: February 18, 2014
    Date of Patent: August 25, 2015
    Assignee: Western Digital Technologies, Inc.
    Inventors: Dean V. Dang, Chun Sei Tsai, Chirag C. Patel, Ammar A. Zayed, Carl E. Barlow, Thao Hieu Banh
  • Patent number: 9093096
    Abstract: Improved flaw scan circuits are provided for repeatable run out data. RRO (repeatable run out) data is processed by counting a number of RRO data bits detected in a servo sector; and setting an RRO flaw flag if at least a specified number of RRO data bits is not detected in the server sector. The RRO flaw flag can also optionally be set by detecting an RRO address mark in the servo sector; counting a number of samples in the servo sector after the RRO address mark that do not satisfy a quality threshold; and setting the RRO flaw flag when the counted number of samples that do not satisfy the quality threshold exceeds a specified flaw threshold. If the RRO flaw flag is set, the RRO data can be discarded, and/or an error recovery mechanism can be implemented to obtain the RRO data.
    Type: Grant
    Filed: July 27, 2012
    Date of Patent: July 28, 2015
    Assignee: LSI Corporation
    Inventor: Viswanath Annampedu
  • 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: 20150109700
    Abstract: Techniques for writing data to a buffer region of a magnetic disk are described. In one example, a hard disk drive comprises a magnetic disk comprising a data buffer region including a first zone and a second zone. Data may be written to the magnetic disk using shingled magnetic recording (SMR) and the buffer region may be an exception region (E-region). A hard disk drive may be configured to calculate a position accuracy value associated with a data writing head. The hard disk drive may select one of the zones based on the position accuracy value. Further, a selected zone may have a determined zone format. The hard disk drive may be configured to write data to the selected zone using the determined zone format.
    Type: Application
    Filed: October 18, 2013
    Publication date: April 23, 2015
    Applicant: HGST Netherlands B.V.
    Inventors: Hidekazu KASHIWASE, Hiroyasu TANABE, Hideki ZAITSU
  • 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: 8995080
    Abstract: Apparatus and method for non-destructive detection of contamination on a slider in a data storage device. In some embodiments, the slider supports a read element adjacent a rotating data recording medium. A non-repeatable runout (NRRO) component of a position error signal (PES) obtained from readback signals transduced from the read element is extracted. A power spectral density (PSD) analysis of the NRRO component is performed to identify a peak power level, and slider contamination is detected responsive to the peak power level.
    Type: Grant
    Filed: September 30, 2014
    Date of Patent: March 31, 2015
    Assignee: Seagate Technology LLC
    Inventors: James Mou, Daniel Brown, Robert German
  • Patent number: 8982501
    Abstract: A data storage device is disclosed comprising a head actuated over a disk, and a spindle motor configured to rotate the disk, wherein the spindle motor comprises a plurality of windings. A commutation controller is configured to commutate the windings based on a commutation sequence. Compensation values are generated based on: A1 sin ?1t+B1 cos ?lt where A1 and B1 are adaptable coefficients and ?1 represents a first frequency based on a first mechanical parameter of the spindle motor. The compensation values are used to drive the commutation sequence of the commutation controller.
    Type: Grant
    Filed: September 22, 2014
    Date of Patent: March 17, 2015
    Assignee: Western Digital Technologies, Inc.
    Inventors: Michael T. Nicholls, Timothy A. Ferris
  • Patent number: 8970979
    Abstract: A disk drive is disclosed comprising a servo control system configured to control an actuator for actuating a head over a disk. Servo sectors are sampled at a servo sample frequency fs to generate a position error signal PES(k) that is filtered with a compensator to generate a first control signal u1(k). A first discrete-time sinusoid comprising a sinusoid frequency of fs+?f is added to the first control signal u1(k) to generate a second control signal u2(k). The second control signal u2(k) is applied to the actuator, and a frequency response of the actuator is determined at the frequency |?f|. The frequency response of the actuator is determined at the frequency fs+?f based at least in part on the frequency response of the actuator at the frequency |?f| and a measured signal of the servo control system when applying the second control signal u2(k) to the actuator.
    Type: Grant
    Filed: December 18, 2013
    Date of Patent: March 3, 2015
    Assignee: Western Digital Technologies, Inc.
    Inventors: Qing Wei Jia, Hui Li, Shuyu Cao, Guoxiao Guo, Jie Yu
  • Publication number: 20150055239
    Abstract: According to one embodiment, a data storage apparatus includes a disk, a head and a controller. In each track, first and second correction values for correcting a track runout in synchronization with rotation of the disk are recorded. The first correction value is for a first position located within a first track, and the second correction value is for a second position located within a second track adjacent to the first track, and separated from the first track by a predetermined distance. The head writes data to or read data from the tracks. The controller corrects the track runout with the first and second correction values, when the head is controlled to position at a target track.
    Type: Application
    Filed: November 4, 2013
    Publication date: February 26, 2015
    Applicant: KABUSHIKI KAISHA TOSHIBA
    Inventor: Takeyori Hara
  • Patent number: 8953278
    Abstract: A disk drive is disclosed comprising a disk, a head, and control circuitry comprising a servo control system operable to actuate the head over the disk. A plurality of disturbance signals is generated in response to a vibration. A plurality of correlations is generated in response to each disturbance signal and an error signal of the servo control system. At least one of the disturbance signals is selected in response to the correlations. A feed-forward compensation value is generated in response to the selected disturbance signal, and the feed-forward compensation value is applied to the servo control system to compensate for the vibration.
    Type: Grant
    Filed: April 15, 2014
    Date of Patent: February 10, 2015
    Assignee: Western Digital Technologies, Inc.
    Inventors: Jianguo Zhou, Wei Xi, Kuang-Yang Tu, Alain Chahwan
  • Patent number: 8953271
    Abstract: A disk drive is disclosed comprising a head actuated over a disk comprising a plurality of servo tracks, wherein each servo track comprises a plurality of servo sectors. A plurality of zones are defined, wherein each zone comprises a plurality of the servo tracks. A metric is generated for each zone, and when the metric for a first zone exceeds a first threshold, feedback compensation values for at least two servo tracks are generated, wherein the feedback compensation values compensate for a written-in error of the servo sectors of each servo track. When the metric for a second zone does not exceed the first threshold, generating feedback compensation values for the second zone is skipped.
    Type: Grant
    Filed: June 27, 2013
    Date of Patent: February 10, 2015
    Assignee: Western Digital Technologies, Inc.
    Inventors: Tanaat Wut Chayarangkan, Julasak Kungsadankosit, Thitinun Jittramatr, Siam Samuhatananon, Chin Yang Choong, Wei Kiat Chen, Eugene Chun-Tsing Wu
  • Patent number: 8934191
    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: January 7, 2014
    Date of Patent: January 13, 2015
    Assignee: Western Digital Technologies, Inc.
    Inventors: Jiangang Liang, Wei Guo
  • Patent number: 8929021
    Abstract: A disk drive is disclosed comprising a head actuated over a disk comprising a plurality of spiral tracks, wherein each spiral track comprising a high frequency signal interrupted at a predetermined interval by a sync mark. An offset r0 representing a difference between an axial rotation of the disk and an axial rotation of the spiral tracks is estimated. Radial dependent timing compensation values are generated in response to the estimated r0. A phase error is generated in response to the sync marks in the spiral track crossings. A control signal is generated in response to the phase error and the radial dependent timing compensation values, and a frequency of an oscillator is adjusted in response to the control signal.
    Type: Grant
    Filed: March 27, 2012
    Date of Patent: January 6, 2015
    Assignee: Western Digital Technologies, Inc.
    Inventors: Jiangang Liang, Wei Guo
  • 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: 8913338
    Abstract: A disk drive is disclosed comprising a disk comprising a plurality of servo tracks defined by servo sectors, wherein each servo sector comprises servo data and a servo compensation value. While servoing a head over a target data track during a write operation, a position error signal (PES) is generated at each servo sector based at least in part on the servo data. When the servo compensation value of a first servo sector is recoverable, the write operation is aborted when the PES generated at the first servo sector exceeds a first write unsafe threshold. When the servo compensation value of the first servo sector is unrecoverable, the write operation is aborted when the PES generated at the first servo sector exceeds a second write unsafe threshold less than the first write unsafe threshold.
    Type: Grant
    Filed: June 24, 2013
    Date of Patent: December 16, 2014
    Assignee: Western Digital Technologies, Inc.
    Inventors: Alain Chahwan, Yanan Huang, Chuanwen Ji
  • Patent number: 8908316
    Abstract: A disk drive is described that uses a vibration sensor to generate a compensating feed-forward control signal to synchronize the write clock frequency with the modulated data island frequency. A linear vibration sensor is positioned with its sensitivity axis aligned with the tangential direction of a track at the radial position of the write head. The tangential component of the external linear vibration is measured by the sensor. The feed-forward control signal derived from the linear vibration sensor modifies the control voltage input to VCO (voltage controlled oscillator) in the write clock generator to adjust the write clock frequency to compensate for the modulated data island frequency caused by the tangential component of the linear vibration.
    Type: Grant
    Filed: December 5, 2011
    Date of Patent: December 9, 2014
    Assignee: HGST Netherlands B.V.
    Inventors: Toshiki Hirano, Xiaotian Sun
  • Patent number: 8902532
    Abstract: A method and computer program product identify the location of a bad block on a disk platter of a hard disk drive, determine an avoidance area extending from the bad block, and prevent data from being written to the avoidance area.
    Type: Grant
    Filed: March 20, 2013
    Date of Patent: December 2, 2014
    Assignee: International Business Machines Corporation
    Inventors: Gary D. Cudak, Lydia M. Do, Christopher J. Hardee, Adam Roberts
  • Patent number: 8896955
    Abstract: A disk drive comprises a track follow control system having a plurality of selectable frequency modes, the track follow control system configured to receive a position error signal and to output a control signal based on the position error signal, wherein the control signal is used by a head assembly to position a head over a disk. The disk drive also comprises a state estimator configured to receive the control signal and a position signal indicating a position of the head, to estimate a disturbance based on the control signal and the position signal, and to output an estimated disturbance signal based on the estimated disturbance. The disk drive further comprises a disturbance evaluator configured to receive the estimated disturbance signal, and to select one of the frequency modes of the track follow control system based on the estimated disturbance signal.
    Type: Grant
    Filed: June 16, 2011
    Date of Patent: November 25, 2014
    Assignee: Western Digital Technologies, Inc.
    Inventors: Min Chen, Alain Chahwan, Shang-Chen Wu, Qixing Zheng, Alexander Babinski, Duc T. Phan
  • Patent number: 8891191
    Abstract: A data storage device is disclosed comprising a disk comprising at least one servo seed pattern, and a head actuated over the disk. An amplitude measurement is generated based on a read signal emanating from the head while reading the disk. A number of times the amplitude measurement exceeds a first threshold is first counted during a first revolution of the disk, and a number of times the amplitude measurement exceeds the first threshold is second counted during a second revolution of the disk. The servo seed pattern is detected based on the first count and the second count.
    Type: Grant
    Filed: May 6, 2014
    Date of Patent: November 18, 2014
    Assignee: Western Digital Technologies, Inc.
    Inventor: Charles A. Park
  • Patent number: 8824262
    Abstract: A disk drive is disclosed wherein a radial offset is measured between a first head and a second head at a plurality of points along a circumference of a corresponding first and second disk surface to generate a first plurality of radial offsets. A first radial offset is determined and a second radial offset is determined based on the first plurality of radial offsets, wherein the first radial offset corresponds to approximately a maximum in the first plurality of radial offsets and the second radial offset corresponds to approximately a minimum in the first plurality of radial offsets. A plurality of access commands are stored in a command queue, and a rotational position optimization (RPO) algorithm is executed to select a next access command to execute from the command queue, wherein the RPO algorithm is responsive to the first and second radial offsets.
    Type: Grant
    Filed: October 11, 2013
    Date of Patent: September 2, 2014
    Assignee: Western Digital Technologies, Inc.
    Inventors: Kexiu Liu, Orhan Beker
  • Patent number: 8804274
    Abstract: According to one embodiment, a disk storage apparatus includes a read controller and a servo controller. The read controller contains a combined position generator including a state observer and a combined position calculator. The servo controller controls a seek operation of the head based on the combined position. The servo controller stores the servo information in a memory and determines an occurrence of a state offset as an error between an actual position of the head and the combined position. The servo controller corrects the predicted position by the state observer based on the servo information stored in the memory and the combined position when the occurrence of the state offset is detected.
    Type: Grant
    Filed: September 4, 2013
    Date of Patent: August 12, 2014
    Assignee: Kabushiki Kaisha Toshiba
    Inventor: Takuji Matsuzawa
  • Patent number: 8773787
    Abstract: A method or apparatus for changing a performance level of a disk drive from an initial performance level to a target performance level, wherein the disk drive includes a profile table. The method including determining an initial performance level, determining a target performance level, determining constant offset values that cause the performance level of the disk drive to match the target performance level, and programming a constant offset table of the profile table with the constant offset values.
    Type: Grant
    Filed: March 29, 2012
    Date of Patent: July 8, 2014
    Assignee: Western Digital Technologies, Inc.
    Inventor: Orhan Beker
  • Patent number: 8755143
    Abstract: A disk drive is disclosed comprising a first disk surface comprising a plurality of tracks, wherein each track comprises a number of data sectors and a number of servo sectors, and a second disk surface comprising a plurality of tracks, wherein each track comprises a number of data sectors and a number of servo sectors. A first repeatable runout (RRO) sinusoid is generated representing an RRO of the first disk surface, and a second RRO sinusoid is generated representing an RRO of the second disk surface. A plurality of access commands are received from a host which are stored in a command queue, and one of the access commands is selected to execute in response to the first and second RRO sinusoids.
    Type: Grant
    Filed: April 27, 2011
    Date of Patent: June 17, 2014
    Assignee: Western Digital Technologies, Inc.
    Inventors: Rebekah A. Wilson, Kenny T. Coker
  • Patent number: 8743503
    Abstract: A disk drive is disclosed comprising a head actuated over a disk comprising a plurality of servo tracks defined by servo sectors. The head is positioned over a first servo track, and a first position error signal (PES) by reading a first servo sector during a first revolution of the disk and in response to a first compensation value. A second compensation value is updated for a second servo sector based on the first PES during the first revolution of the disk. A second PES is generated by reading the second servo sector during the first revolution of the disk and in response to the updated second compensation value. The first compensation value is updated for the first servo sector based on the second PES during the first revolution of the disk. The head is actuated over the disk in response to the first PES and the second PES.
    Type: Grant
    Filed: March 11, 2013
    Date of Patent: June 3, 2014
    Assignee: Western Digital Technologies, Inc.
    Inventors: Shan Tang, Hengchang Guo
  • Patent number: 8743495
    Abstract: A disk drive is disclosed comprising a head actuated over a disk comprising a plurality of non-circular servo tracks for defining a plurality of substantially circular tracks. Each non-circular servo track comprises a plurality of servo sectors defining a plurality of servo wedges. The head is positioned at a first offset relative to a first circular track and a relationship of servo bursts for each servo wedge is first generated. The head is positioned at a second offset relative to the first circular track and the relationship of the servo bursts for each servo wedge is second generated. For each servo wedge, a selection is made between the first generated relationship at the first offset and the second generated relationship at the second offset, and the servo bursts at the selected offset are evaluated to generate a track squeeze indicator.
    Type: Grant
    Filed: June 3, 2011
    Date of Patent: June 3, 2014
    Assignee: Western Digital Technologies, Inc.
    Inventors: Min Chen, Duc T. Phan
  • Patent number: 8737013
    Abstract: A disk drive is disclosed comprising a disk, a head, and control circuitry comprising a servo control system operable to actuate the head over the disk. A plurality of disturbance signals is generated in response to a vibration. A plurality of correlations is generated in response to each disturbance signal and an error signal of the servo control system. At least one of the disturbance signals is selected in response to the correlations. A feed-forward compensation value is generated in response to the selected disturbance signal, and the feed-forward compensation value is applied to the servo control system to compensate for the vibration.
    Type: Grant
    Filed: November 16, 2011
    Date of Patent: May 27, 2014
    Assignee: Western Digital Technologies, Inc.
    Inventors: Jianguo Zhou, Wei Xi, Kuang-Yang Tu, Alain Chahwan