Distinct Servo Sector Patents (Class 360/77.08)
  • Patent number: 7746594
    Abstract: A disk drive is disclosed comprising a disk having servo data defining a plurality of servo tracks. The servo data comprises a preamble, and a plurality of slanted line servo bursts recorded at a tilt angle with respect to the preamble. The slanted line servo bursts comprises a first plurality of slanted line servo bursts and a second plurality of slanted line servo bursts, wherein the second plurality of slanted line servo bursts are offset radially from the first plurality of slanted line servo bursts. A position error signal (PES) is generated in response to a phase difference when reading the preamble and the slanted line servo bursts.
    Type: Grant
    Filed: September 29, 2008
    Date of Patent: June 29, 2010
    Assignee: Western Digital Technologies, Inc.
    Inventors: Guoxiao Guo, Jie Yu
  • Patent number: 7746593
    Abstract: According to one embodiment, a disk drive is disclosed which has an offset measuring function for measuring a dynamic offset value necessary to a dynamic offset control using a DTM (discrete track media) type disk. A CPU (microprocessor) included in the disk drive writes offset measuring position information to an optimum position of lands on the disk and calculates a dynamic offset value based on the offset measuring position information.
    Type: Grant
    Filed: February 24, 2009
    Date of Patent: June 29, 2010
    Assignee: Kabushiki Kaisha Toshiba
    Inventor: Daisuke Sudo
  • Patent number: 7746595
    Abstract: A disk drive is disclosed comprising a disk having servo data defining a plurality of servo tracks. The servo data comprises a preamble, and a plurality of slanted line servo bursts recorded at a tilt angle with respect to the preamble. At least one of the slanted line servo bursts comprises a first polarity along a first segment of the slanted line and a second polarity along a second segment of the slanted line. A position error signal (PES) is generated in response to a phase difference when reading the preamble and the slanted line servo bursts.
    Type: Grant
    Filed: September 29, 2008
    Date of Patent: June 29, 2010
    Assignee: Western Digital Technologies, Inc.
    Inventors: Guoxiao Guo, Jie Yu
  • Publication number: 20100128384
    Abstract: According to one embodiment, a magnetic recording medium to which a signal is recorded by reversing magnetization of a magnetic body, includes: a servo region to which a servo signal is written; a data region configured to include a magnetic region of a track to which data is written, the magnetic region being separated from other magnetic region of other track; and a periodic magnetic pattern region configured to be provided at a head portion of the data region following the servo region, and is inclined at a predetermined angle with respect to a circumferential direction of the magnetic recording medium, over a predetermined length in a radius direction of the magnetic recording medium.
    Type: Application
    Filed: January 27, 2010
    Publication date: May 27, 2010
    Applicant: TOSHIBA STORAGE DEVICE CORPORATION
    Inventor: Motomichi SHIBANO
  • Publication number: 20100123973
    Abstract: According to one embodiment, an information storage medium includes a plurality of sectors arranged in a circumferential direction of a disk-shaped substrate, each sector having a servo pattern that is formed on the substrate and in which information indicating a position in a radial direction of the substrate is magnetically recorded, and a plurality of recording dots that is arranged with a predetermined pitch in the circumferential direction of the substrate and in which information is to be magnetically recorded. The servo pattern has a magnetic pattern arranged in the circumferential direction with a pitch having a predetermined integral ratio to the pitch of the recording dots. A recording dot arranged nearest to the servo pattern among the recording dots in each sector is arranged at a position having a constant phase relationship to the pitch of the servo pattern of the sector comprising the recording dots in any of the sectors.
    Type: Application
    Filed: September 29, 2009
    Publication date: May 20, 2010
    Applicant: FUJITSU LIMITED
    Inventors: Yasuyuki Ozawa, Haruhiko Izumi
  • Patent number: 7719789
    Abstract: A magnetic storage medium has tracks and guard bands magnetically separating adjacent tracks. The tracks and the guard bands are alternately and concentrically disposed. The tracks includes a plurality of data tracks in which data can be written and from which data can be reproduced and servo patterns disposed between the data tracks and allowing reproduction of positional information of the data tracks. The magnetic storage medium includes an offset-amount measurement area in which traverse tracks are formed so as to traverse adjacent tracks via each of the guard bands so that writing regarding offset measurement data for measuring an offset amount between a storage element and a reproducing element of a magnetic head unit is allowed at a center position of the storage element.
    Type: Grant
    Filed: January 8, 2009
    Date of Patent: May 18, 2010
    Assignee: Toshiba Storage Device Corporation
    Inventor: Nobuhide Aoyama
  • Patent number: 7715144
    Abstract: A method of measuring a track value is shown. The track value is related to track mis-registration, and is compared to a track value limit to assess a condition of the track. In example embodiments, the track value is determined as a function of multiple position error signals from previous wedges in the track. During a self servo writing operation, the track value and the track value limit are used to selectively perform a recovery action. In example embodiments, the track value limit is dynamically adjusted.
    Type: Grant
    Filed: March 31, 2008
    Date of Patent: May 11, 2010
    Assignee: Kabushiki Kaisha Toshiba
    Inventor: Anton Gerasimov
  • Patent number: 7710676
    Abstract: A disk drive is disclosed comprising a disk including a plurality of servo tracks defined by a plurality of servo sectors, wherein each servo sector comprises a plurality of servo bursts. The disk drive further comprises a head actuated over the disk. A servo sector is read to generate a read signal which is processed to demodulate the servo bursts into a position error signal (PES) representing an offset of the head from a target radial location on the disk. The read signal is also processed to decode the servo bursts into a Gray codeword representing at least part of a servo track address, wherein the servo track address represents a servo track the head is over.
    Type: Grant
    Filed: March 27, 2008
    Date of Patent: May 4, 2010
    Assignee: Western Digital Technologies, Inc.
    Inventor: Jack M. Chue
  • Patent number: 7697233
    Abstract: A disk drive is disclosed comprising a disk, a head, and an actuator for actuating the head over the disk. The disk drive further comprises a state variable memory for storing a plurality of state variable sets, wherein each state variable set comprises a plurality of state variables and each state variable set corresponds to a task object. A coefficient memory for stores a plurality of coefficient sets, wherein each coefficient set comprises a plurality of coefficients and each coefficient set corresponds to a task object. A task object is executed by initializing a base state register to address a selected one of the state variable sets in the state variable memory, and initializing a base coefficient register to address a selected one of the coefficient sets in the coefficient memory.
    Type: Grant
    Filed: October 21, 2008
    Date of Patent: April 13, 2010
    Assignee: Western Digital Technologies, Inc.
    Inventors: George J. Bennett, Orhan Beker, Aswartha Narayana
  • Publication number: 20100079904
    Abstract: A control method includes determining whether a size of write data specified by a command supplied from a host is smaller than a size of a physical sector of a recording medium, lowering priority of the write data when the size of the write data is smaller than the size of the physical sector, continuously reading, when a plurality of commands for write data having lowered priority are supplied, data in physical sectors specified in the plurality of commands, and executing a modify write process on the basis of a result of continuously reading the data.
    Type: Application
    Filed: July 10, 2009
    Publication date: April 1, 2010
    Applicant: FUJITSU LIMITED
    Inventor: Noriyuki Sato
  • Patent number: 7688539
    Abstract: A disk drive is disclosed comprising a disk, and a head actuated over the disk. The head is positioned at a radial location over the disk, and a servo burst is written at the current radial location. The servo burst is read to generate a read signal, and the read signal is processed to generate a position error signal (PES). The head is moved radially in response to the PES, and the process is repeated multiple times to form a spiral track spanning at least one revolution of the disk.
    Type: Grant
    Filed: May 14, 2008
    Date of Patent: March 30, 2010
    Assignee: Western Digital Technologies, inc.
    Inventors: Lawrence M. Bryant, Yakov M. Lifchits, Siri S. Weerasooriya
  • Publication number: 20100073811
    Abstract: A magnetic disk includes: a data recording region having first magnetic parts; the first magnetic parts being arranged in a circumferential direction in the nonmagnetic region and form tracks, and the tracks being arranged in a radial direction at a track pitch Tp; and a burst pattern region having burst patterns making a magnetic head follow the first magnetic parts, the burst patterns having second magnetic parts, the second magnetic parts forming base units arranged at a pitch Sp in a radial direction of the disk, the pitch Sp being more than large as the track pitch Tp, the base units including a plurality of base units arranged in a circumferential direction of the disk, and the base units adjacent to each other in the circumferential direction being displaced from each other by the pitch Sp in the radial direction of the disk.
    Type: Application
    Filed: August 18, 2009
    Publication date: March 25, 2010
    Applicant: FUJITSU LIMITED
    Inventor: Yukio Hirai
  • Publication number: 20100073810
    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: Application
    Filed: September 19, 2008
    Publication date: March 25, 2010
    Inventors: Mustafa Can Ozturk, Puskal Prasad Pokharel
  • Publication number: 20100067142
    Abstract: A recordable medium according to some embodiments includes a servo control field having a bit patterned media (BPM) pattern. The pattern includes a plurality of isolated magnetic islands or dots arranged in a down-track orientation and in a cross-track orientation. A phase of dots arranged on the medium in the servo control field varies in a first cross-track direction. The dots arranged on the medium may include a first phase pattern that has a first phase gradient in the first cross-track direction and a second phase pattern that has a second phase gradient, different from the first phase gradient, in the first cross-track direction. The dots may include a plurality of dot composites including a plurality of dots.
    Type: Application
    Filed: September 15, 2008
    Publication date: March 18, 2010
    Inventors: Puskal Prasad Pokharel, Mustafa Can Ozturk
  • Patent number: 7675700
    Abstract: Embodiments of the present invention provide a magnetic disk device and a method for production thereof, the magnetic disk device being characterized in that the magnetic disk therein permits a plurality of tracks thereon to record correction data when necessary without decreasing its storage capacity. According to one embodiment, the magnetic disk device is characterized in that the magnetic disk has the first tracks and the second tracks formed thereon, the first tracks having servo data regions arranged cyclically, with a portion of a region between them being the correction data region and the remaining regions being the user data region, and the second tracks having the servo data regions arranged cyclically, with the region between them being the user data regions, and the multiprocessing unit (MPU) switches the servo extraction timing of the position information sampler depending on whether the track for servo reproduction by the magnetic head is the first track or the second track.
    Type: Grant
    Filed: March 26, 2008
    Date of Patent: March 9, 2010
    Assignee: Hitachi Global Storage Technologies Netherlands B.V.
    Inventors: Sumie Takeda, Nobuya Matsubara, Nobuyuki Kitazaki, Toshifumi Kumano
  • Patent number: 7672075
    Abstract: In a magnetic recording medium including a servo pattern region having a servo pattern formed of a concave/convex pattern having convex portions and concave portions and a data recording region, the region having a data track pattern, the convex portions are formed in an address pattern region of the servo pattern region such that the maximum opening lengths, which are located in the respective same radius regions of the respective opening lengths along the rotating direction of a substrate of the concave portions constituting the concave/convex pattern are set to first lengths that are double the minimum opening lengths along the rotating direction of the concave portions in the respective same radius regions. With this arrangement, the magnetic recording medium can securely read a magnetic signal and has a servo pattern having excellent surface smoothness.
    Type: Grant
    Filed: November 3, 2005
    Date of Patent: March 2, 2010
    Assignee: TDK Corporation
    Inventors: Yoshikazu Soeno, Kazuya Shimakawa
  • Patent number: 7672073
    Abstract: A method for operating a head testing apparatus or, more generally, a host hard disk drive using a mounted hard disk that has had its servo track information pre-written in an external servo-writing apparatus rather than in the head testing or host apparatus itself. The method eliminates repeatable errors and repeatable runout by effectively replacing the pre-written servo tracks, which are eccentric, with new track profiles that are tracked like circular tracks. The problem of repeatable errors is caused by repeatable runout superimposed upon written-in position errors when a disk written in one machine is transferred to another. This problem is eliminated by forming IRON (Iterative Repeatable Runout Nulling) profile tracks from the initially pre-written servo tracks, where the IRON profile tracks are effectively tracked as concentric circular tracks and generate no PES.
    Type: Grant
    Filed: February 14, 2008
    Date of Patent: March 2, 2010
    Assignee: Headway Technologies, Inc.
    Inventors: Lou Shrinkle, Peter Crill, Matthew Yee, David Hu
  • Patent number: 7667920
    Abstract: A method for correcting a track pitch error in servo tracks written on a magnetic recording media coupled with a disk surface, by using a subsequent servo-write pass, comprises propagating servo tracks across the magnetic recording media in a previous servo-write pass. The servo tracks have radial positioning servo code. The servo tracks enable a magnetic transducer to be positioned to at least one radial position on the magnetic recording media. At least one corrected radial reference point is calculated for the track pitch error written on the magnetic recording media, by identifying at least one inconsistency between a mechanical response of an actuator and the track pitch. A corrected location for at least one servo track is identified. At least one new servo track at the corrected location is propagated with the subsequent servo-write pass. Optimum data track distribution across the disk surface and optimum reading and writing of data to and from the magnetic recording media is enabled.
    Type: Grant
    Filed: December 28, 2007
    Date of Patent: February 23, 2010
    Assignee: Hitachi Global Storage Technologies Netherlands B.V.
    Inventors: Satyajit N. Patwardhan, Steven C. Smith
  • Patent number: 7656606
    Abstract: A rotary-type magnetic recording medium has servo patterns formed in servo pattern regions on a substrate by patterns including recording regions and non-recording regions. Burst signal units composed of the recording regions or the non-recording regions are formed in burst pattern regions in the servo pattern regions. The burst signal units are formed so that for at least one edge out of both edges along a direction of rotation of the magnetic recording medium, a center in the direction of rotation is positioned closer to the other edge than both ends in the direction of rotation, and a ratio of a length along a radial direction of the magnetic recording medium between both ends and the center of the one edge to a length along the radial direction between both ends of the one edge and both ends of the other edge is in a range of 0.2 or below.
    Type: Grant
    Filed: November 23, 2007
    Date of Patent: February 2, 2010
    Assignee: TDK Corporation
    Inventors: Kasuyuki Nakada, Mitsuru Takai, Kazuhiro Hattori
  • Publication number: 20100020436
    Abstract: A magnetic disk apparatus includes a magnetic disk, a magnetic head, a servo reproduction signal generator and a magnetic head controller. The disk includes a data recording area and a servo-pattern area. The data recording area includes a non-magnetic area scattered with magnetic regions, and the servo-pattern area includes uniformly magnetized magnetic regions larger than the magnetic regions in the recording area. The magnetic head reciprocates radially of the disk, giving a magnetization direction to the magnetic regions in the data recording area and reading the magnetization direction of the magnetic regions in the data recording area and the servo-pattern area. The servo reproduction signal generator reads the servo-pattern area, using the magnetic head, via an absolute-value calculation circuit to generate a servo reproduction signal before the recording or reading with respect to the data recording area.
    Type: Application
    Filed: June 5, 2009
    Publication date: January 28, 2010
    Applicant: FUJITSU LIMITED
    Inventors: Mineo Moribe, Masakazu Taguchi, Kazuyuki Ozaki
  • Patent number: 7643235
    Abstract: Timing recovery and synchronization for data communication is utilized. A pilot sequence of signals can be selected to improve recovery of a phase offset and a frequency offset in a communication system. Sampling instances can further be adjusted based on pilot sequences within a user data portion.
    Type: Grant
    Filed: September 28, 2006
    Date of Patent: January 5, 2010
    Assignee: Seagate Technology LLC
    Inventors: Mehmet Fatih Erden, Erozan Mehmet Kurtas, Mark Edward Re
  • Patent number: 7643234
    Abstract: Servo patterns and associated methods of fabricating servo patterns are described. For patterned storage media, data sectors and servo sectors may be patterned using self-assembly. In one embodiment, self-assembly is used to form a first array of islands and a second array of islands in servo sectors that are track-wise offset. A servo writing process is then performed to write a desired servo pattern in the arrays, such as for burst fields, synchronization fields, etc.
    Type: Grant
    Filed: December 26, 2007
    Date of Patent: January 5, 2010
    Assignee: Hitachi Global Storage Technologies Netherlands, B.V.
    Inventors: Thomas R. Albrecht, Zvonimir Z. Bandic, Xiao Z. Wu
  • Patent number: 7630156
    Abstract: On a rotary-type magnetic recording medium, servo patterns are formed in servo pattern regions on one surface and the other surface of a disk-shaped substrate by patterns including recording regions and non-recording regions. In the servo pattern regions on both the one surface and the other surface, plural functional regions are defined in order in a direction of rotation of the magnetic recording medium. In the pattern formed in at least one region out of the plural functional regions on the one surface, the non-recording regions are formed at formation positions on the one surface corresponding to formation positions of the recording regions on the other surface and the recording regions are formed at formation positions on the one surface corresponding to formation positions of the non-recording regions on the other surface.
    Type: Grant
    Filed: January 11, 2008
    Date of Patent: December 8, 2009
    Assignee: TDK Corporation
    Inventors: Shuichi Okawa, Kazuhiro Hattori, Makoto Moriya
  • Publication number: 20090290254
    Abstract: A magnetic storage medium has tracks and guard bands magnetically separating adjacent tracks. The tracks and the guard bands are alternately and concentrically disposed. The tracks includes a plurality of data tracks in which data can be written and from which data can be reproduced and servo patterns disposed between the data tracks and allowing reproduction of positional information of the data tracks. The magnetic storage medium includes an offset-amount measurement area in which traverse tracks are formed so as to traverse adjacent tracks via each of the guard bands so that writing regarding offset measurement data for measuring an offset amount between a storage element and a reproducing element of a magnetic head unit is allowed at a center position of the storage element.
    Type: Application
    Filed: January 8, 2009
    Publication date: November 26, 2009
    Applicant: FUJITSU LIMITED
    Inventor: Nobuhide Aoyama
  • Patent number: 7616399
    Abstract: A disk drive comprising a moveable head, a disk, and a servo controller that implements servo control techniques to preserve PES continuity during track following operations is disclosed. The disk includes a plurality of tracks in which a substantial majority of the tracks include a plurality of servo sectors having a plurality of servo bursts that are utilized in track following operations. The servo controller controls track following operations with the moveable head and implements operations to preserve PES continuity during track following. These operations include: dividing tracks of the disk into a plurality of zones wherein each zone includes zone boundaries; and utilizing a PES equation for each zone to generate a PES value based upon read servo bursts wherein each zone PES equation includes a normalizing factor to account for boundary conditions associated with zone boundaries to preserve PES value continuity between zones.
    Type: Grant
    Filed: December 7, 2006
    Date of Patent: November 10, 2009
    Assignee: Western Digital Technologies, Inc.
    Inventors: Min Chen, Zhi Wang, Duc T. Phan
  • Patent number: 7602576
    Abstract: A disk drive correctly recognizes newly written data when a plurality of readable data exist on the same sector of the same track, by comparing AGC values of each of the readable data, comparing error rates generated by Viterbi decoding, or both. An offset value determining means determines whether an offset value when the data is read has exceeded a predetermined value when the data is read. An offset control means controls the head, on the basis of the determination result of the offset value determining means, to conduct the offset operation on the opposite side of the track when the data is read the first time, and a selecting means selects the new data recorded in the sector by comparing the results obtained for both sets of data.
    Type: Grant
    Filed: May 10, 2007
    Date of Patent: October 13, 2009
    Assignee: Fujitsu Limited
    Inventor: Osamu Yoshida
  • Patent number: 7602575
    Abstract: A disk drive is disclosed comprising control circuitry for self servo writing a disk. An estimated reader/writer offset is initialized, servo bursts in a first servo track are read, the head is moved radially using the estimated reader/writer offset, and propagated servo bursts are written to a target servo track. The propagated servo bursts are read from the target servo track to generate a read signal, the read signal is processed to generate a burst crossing signal (BCS), and the estimated reader/writer offset is adjusted in response to the BCS.
    Type: Grant
    Filed: May 14, 2008
    Date of Patent: October 13, 2009
    Assignee: Western Digital Technologies, Inc.
    Inventors: Yakov M. Lifchits, Lawrence M. Bryant, Siri S. Weerasooriya, Wing Ying
  • Patent number: 7595954
    Abstract: Disclosed is a method of estimating repeatable runout (RRO) for a disk drive. The method includes: determining a plurality of position error signal (PES) values for a plurality of servo wedges of a track of a disk; and estimating repeatable runout (RRO) in the PES values for the servo wedges of the track by averaging determined PES values over a pre-determined number of revolutions of the disk of the disk drive and scaling the averaged PES values by a pre-determined ratio of the variance of non-repeatable runout (NRRO) to the variance of an optimal estimation of the RRO for the disk drive.
    Type: Grant
    Filed: April 18, 2006
    Date of Patent: September 29, 2009
    Assignee: Western Digital Technologies, Inc.
    Inventors: Min Chen, Li Yi
  • Patent number: 7595955
    Abstract: Embodiments of the present invention help to achieve a read error recovery, and suppress decreases in the capacity of the disk drive device and degradation in performance. In one embodiment, a hard disk drive (HDD) performs following control without use of repeatable run-out (RRO) compensation information on a magnetic disk in a normal reading process. When an error occurs in a normal reading process, the HDD moves a read element to a position different from a target position of the normal reading process. At the position where the read element has been moved, the read element reads out the RRO compensation information. In a recovery procedure for the reading process where the error has occurred, the HDD performs following control with compensation by the servo compensation information read out by the read element.
    Type: Grant
    Filed: February 7, 2008
    Date of Patent: September 29, 2009
    Assignee: Hitachi Global Storage Technologies Netherlands B.V.
    Inventors: Mirei Hosono, Kazunari Tsuchimoto, Hideki Ohzeki, Tetsuo Ueda, Isao Yoneda, Kazuyuki Ishibashi, Hiroshi Uchida
  • Publication number: 20090237832
    Abstract: A sequential data storage medium, comprising a sequence of plurality of servo patterns that provide lateral position information and longitudinal position information, wherein each of the plurality of servo patterns comprises a first burst comprising a first plurality of pulses, a second burst comprising a second plurality of pulses, a third burst comprising a third plurality of pulses, and a fourth burst comprising a fourth plurality of pulses. The spacings between the first plurality of pulses, in combination with the spacings between the second plurality of pulses, encode a first bit without affecting the recovery of lateral position information. The spacings between the third plurality of pulses, in combination with the spacings between the fourth plurality of pulses, encode a second bit without affecting the recovery of lateral position information.
    Type: Application
    Filed: March 20, 2008
    Publication date: September 24, 2009
    Applicant: INTERNATIONAL BUSINESS MACHINES CORPORATION
    Inventors: GIOVANNI CHERUBINI, ROY DARON CIDECIYAN, EVANGELOS S. ELEFTHERIOU, ROBERT ALLEN HUTCHINS
  • Patent number: 7589929
    Abstract: There is provided a technique capable of eliminating the need to create data for compensating the displacement of a servo pattern occurring at the time of writing the servo pattern using an amplitude method and thereby of significantly reducing the production time of a disk medium. A servo pattern writing apparatus that uses a write head to write a servo pattern on a recording medium according to an amplitude method, comprises: a position sensor that detects the displacement amount of the write head with respect to its reference position in the track crossing direction; and a delay amount adjustment circuit that writes a servo pattern in correspondence with a servo pattern write phase amount which is set for compensating the displacement amount detected by the position sensor at the time of demodulation of the servo pattern.
    Type: Grant
    Filed: September 17, 2007
    Date of Patent: September 15, 2009
    Assignee: Fujitsu Limited
    Inventor: Tatsuro Sasamoto
  • Patent number: 7586713
    Abstract: A control apparatus, storage apparatus and control method uses a correction value for head position written in a recording medium to control head position and prevents a use of a correction value that has improperly been read out. The apparatus comprises: an allowable range acquisition section that acquires a correction value allowable range which is a previously set allowable range of a correction value; and a head position control section that controls head position using a read out correction value in the case where the correction value that has been read out from the recording medium falls within the correction value allowable range acquired by the allowable range acquisition section.
    Type: Grant
    Filed: July 31, 2006
    Date of Patent: September 8, 2009
    Assignee: Fujitsu Limited
    Inventors: Fumiya Kudo, Mitsuo Kamimura
  • Patent number: 7583469
    Abstract: An apparatus, method, and system for providing a fine adjustment for transducing head positioning in a hard disk drive (HDD). The apparatus, method, and system include reading a positioning error field wherein the resulting signal is a substantially sinusoidal position error signal (PES), filtering the PES to remove low frequencies and attenuate high frequencies, sample the filtered PES at a multiple of the channel frequency, filter the higher frequency harmonics, down sample the PES, and provide a signal proportional to the amplitude of the down sampled PES. This signal is the reference signal to the head positioning servo.
    Type: Grant
    Filed: December 28, 2006
    Date of Patent: September 1, 2009
    Assignee: Marvell International Ltd.
    Inventors: Pantas Sutardja, Michael B. Madden
  • Patent number: 7580212
    Abstract: The present invention may be embodied in a magnetic disk, of a disk drive, having eight-bit fields storing wedge repeatable runout (WRRO) compensation values and redundancy information. The WRRO compensation value of each field includes a six-bit binary value of which five bits represent a compensation magnitude and one bit represents a sign bit indicating a compensation direction. The redundancy information of each field has a first bit based on the sign bit.
    Type: Grant
    Filed: March 30, 2006
    Date of Patent: August 25, 2009
    Assignee: Western Digital Technologies, Inc.
    Inventors: John Yin Kwong Li, David Dung Tien Nguyen
  • Patent number: 7580218
    Abstract: A method for operating a head testing apparatus (spin stand) using a mounted hard disk that has had its servo track information pre-written in an external servo-writing apparatus rather than in the testing apparatus itself. This insures more accurate servo-track writing and renders the testing operation more efficient. The problem of repeatable runout (RRO) associated with the transfer of a disk written in one machine to another is eliminated by forming a corrected position error signal (PES) by subtracting the average offset of one or more servo sector locations previously calculated using limited bandwidth operation of the servomechanism, from the position error signal generated during full bandwidth servo operation of the apparatus.
    Type: Grant
    Filed: September 1, 2005
    Date of Patent: August 25, 2009
    Assignee: Headway Technologies, Inc.
    Inventors: Lou Shrinkle, David Hu, Peter Crill, Matthew Yee
  • Patent number: 7580216
    Abstract: Systems and techniques to write servo patterns on machine-readable media. In general, in one implementation, the technique includes: obtaining timing information from a spiral servo reference track on a machine-readable medium to determine head position, and generating a servo track with servo information based on the determined head position. Obtaining the timing information can involve determining a peak position of a diamond-shaped waveform and identifying occurrences of a timing-reference symbol in the spiral servo reference track. Moreover, identifying occurrences of the timing-reference symbol can involve decoding an encoded repeating pattern using multiple framings, correlating signal samples that indicate pattern transitions with valid pattern transitions as defined by the encoding, accumulating the transition pattern correlations for the multiple framings, selecting one of the multiple framings as a correct framing, and determining a waveform polarity for the signal.
    Type: Grant
    Filed: December 10, 2007
    Date of Patent: August 25, 2009
    Assignee: Marvell International Ltd.
    Inventors: Ke Han, Pantas Sutardja, Rui Cao
  • Publication number: 20090207522
    Abstract: On a magnetic recording medium, M sets of burst patterns are formed along a direction of rotation of a substrate in each burst pattern region, where M is a natural number of two or higher. Each burst pattern is formed so as to include two types of burst signal units that are positioned at different distances from a center of data track patterns and have an equal length along a radial direction of the substrate. The length along the radial direction is (2·M/N) times the track pitch, where N is a natural number of two or higher.
    Type: Application
    Filed: April 30, 2009
    Publication date: August 20, 2009
    Applicant: TDK CORPORATION
    Inventors: Akimasa KAIZU, Yoshikazu SOENO, Makoto MORIYA
  • Patent number: 7576941
    Abstract: A disk drive is disclosed comprising a plurality of servo sectors that define a plurality of tracks, and a head comprising a read element radially offset from a write element. The read element is positioned over a first track, and the first track is read to generate first read wedge repeatable runout (WRRO) values. A first seek operation of the head positions the read element over a second track, and the second track is read to generate first write WRRO values. The first write WRRO values are used to write the first read WRRO values to the first track. A second seek operation of the head positions the read element over a third track, and the third track is read to generate second write WRRO values. The second write WRRO values are used to write the first write WRRO values to the second track.
    Type: Grant
    Filed: October 26, 2007
    Date of Patent: August 18, 2009
    Assignee: Western Digital Technologies, Inc.
    Inventors: Teddy T. C. Chen, Eugene Chun-Tsing Wu, John Yin Kwong Li, Jie Yu, Jonathan V. Nguyen, Tuong M. Vu, Guoxiao Guo
  • Patent number: 7576942
    Abstract: A method and system determines the position of a transducer head based on permanent servo marks in which the width of the permanent servo marks is greater than the width of the data tracks they are used to identify. The method includes receiving readback signals in response to the permanent servo marks arranged as a number of null bursts and generating position error signals with respect to each null burst. Region based information is extracted based on the position error signals, and the region based information is used in conjunction with the position error signals to generate region-based displacement estimates with respect to each null burst. The region-based estimates are then combined to generate a final displacement estimate that describes the estimated distance between a transducer head and the centerline of a desired data track.
    Type: Grant
    Filed: April 22, 2008
    Date of Patent: August 18, 2009
    Assignee: Seagate Technology LLC
    Inventors: Darren William Karns, Mark David Bedillion, Qiang Ling, Mehmet Fatih Erden
  • Patent number: 7573669
    Abstract: Embodiments in accordance with the present invention ensure that the pitch of a servo write track is accurately controlled. According to one embodiment of the present invention, a Self Servo Write (SSW) uses different methods and sequences to identify read-write offsets (RWOs) and calculate target positions in inner and outer diameter sides of a magnetic disk. In the inner diameter-side area, the SSW controller uses the readout of a radial pattern written on a recording surface and a reference value to identify the RWO. The SSW controller uses the RWO value identified in the inner diameter-side area to anticipate an RWO value in the outer diameter-side area. In the outer diameter-side area, the SSW controller uses the anticipated RWO value to determine the target position of each servo write track.
    Type: Grant
    Filed: April 19, 2007
    Date of Patent: August 11, 2009
    Assignee: Hitachi Global Storage Technologies Netherlands B.V.
    Inventors: Manabu Saikawa, Atsushi Takeichi, Kazuhiko Washizu
  • Publication number: 20090195918
    Abstract: The information reproducing method manages an average magnetization state of each sector on a bit-patterned recording medium as sector management information and sets an information reproduction condition for the sector on the bit-patterned recording medium, based on the sector management information.
    Type: Application
    Filed: January 30, 2009
    Publication date: August 6, 2009
    Inventor: Nobuhide AOYAMA
  • Publication number: 20090195917
    Abstract: According to one embodiment, a hard disc apparatus comprises a disc, wherein areas between neighboring servo areas are allocated to data areas including data sectors, a head module, and a storage module configured to store head alignment data, wherein the head alignment data are defined for the data areas, and includes information indicating an interval from the servo area to a first data sector, information indicating a data area in one track, a first data sector which is a start sector of the track, and information indicating the presence/absence of a defective sector including a primary defect, and the start sector of a track including the defective sector is a data sector next to the defective sector.
    Type: Application
    Filed: January 29, 2009
    Publication date: August 6, 2009
    Applicant: KABUSHIKI KAISHA TOSHIBA
    Inventors: Yuma Aso, Yasuhiko Ichikawa
  • Patent number: 7567406
    Abstract: Embodiments of the present invention provide accurate pitch control of a servo write track. A Self-Servo-Write (SSW) according to an embodiment of the present invention determines a reference APC by reading a mark formed on the recording surface corresponding to the propagation head prior to starting the product servo pattern writing. The accurate size of the mark in the radial direction is known previously. The reference APC is for determining the track pitch, and by using the mark with the determined size, the product servo patterns can be written with a desired and accurate track pitch.
    Type: Grant
    Filed: July 20, 2007
    Date of Patent: July 28, 2009
    Assignee: Hitachi Global Storage Technologies Netherlands B.V.
    Inventors: Hideki Ohzeki, Kazuyuki Ishibashi, Shunichiroh Ohta, Tatsuo Takagi
  • Publication number: 20090185308
    Abstract: On a magnetic recording medium, M sets of burst patterns are formed along a direction of rotation of a substrate in each burst pattern region, where M is a natural number of two or higher. Each burst pattern is formed so as to include two types of burst signal units that are positioned at different distances from a center of data track patterns and have an equal length along a radial direction of the substrate. The length along the radial direction is (2·M/N) times the track pitch, where N is a natural number of two or higher.
    Type: Application
    Filed: March 27, 2009
    Publication date: July 23, 2009
    Applicant: TDK CORPORATION
    Inventors: Akimasa KAIZU, Yoshikazu SOENO, Makoto MORIYA
  • Patent number: 7561371
    Abstract: A magnetic disk incorporated into a magnetic disk device is divided radially into a plurality of areas. An inner-circumference area has servo information written thereon at a low frequency. An outer-circumference area has servo information written thereon at a high frequency. The magnetic disk device creates concentric tracks on the magnetic disk with a magnetic disk rotation center as the center of the concentric tracks and selects a dividing track that acts as a demarcation for switching the area from which servo information will be read. The magnetic disk device then deletes all the servo information that is not going to be read in each of the areas divided by the dividing track.
    Type: Grant
    Filed: September 19, 2006
    Date of Patent: July 14, 2009
    Assignee: Fujitsu Limited
    Inventors: Kazunori Mori, Isamu Tomita
  • Patent number: 7561359
    Abstract: The present invention is directed to a method and apparatus for providing an absolute reference point on a disk surface of a disk drive. A write head associated with the disk surface is used to write spirals of servo information thereon, for example, under control of a servo track writer. The spirals of servo information include standard spirals and special spirals. In one embodiment, the special spirals are shorter than the standard spirals and the special spirals are rotationally non-symmetric. For example, an unequal number of standard spirals are interposed between one pair of adjacent special spirals relative to the number of standard spirals interposed between other pairs of adjacent special spirals. The special spirals may take a variety of other forms to distinguish themselves from standard spirals.
    Type: Grant
    Filed: June 2, 2004
    Date of Patent: July 14, 2009
    Assignee: Maxtor Corporation
    Inventors: Jay Jeong, Tim Everett, Stan Shepherd
  • Publication number: 20090168229
    Abstract: Servo patterns and associated methods of fabricating servo patterns are described. For patterned storage media, data sectors and servo sectors may be patterned using self-assembly. In one embodiment, self-assembly is used to form a first array of islands and a second array of islands in servo sectors that are track-wise offset. A servo writing process is then performed to write a desired servo pattern in the arrays, such as for burst fields, synchronization fields, etc.
    Type: Application
    Filed: December 26, 2007
    Publication date: July 2, 2009
    Inventors: Thomas R. Albrecht, Zvonimir Z. Bandic, Xiao Z. Wu
  • Publication number: 20090168230
    Abstract: A magnetic disk for a hard disk drive comprising a plurality of physical sector sizes is disclosed. The magnetic disk includes a first sector size area physically formatted according to a first physical sector size and a second sector size area physically formatted according to a second physical sector size different from the first sector size by a multiple of the first sector size wherein the second sector size can be presented externally as multiple sectors of said first sector size.
    Type: Application
    Filed: December 28, 2007
    Publication date: July 2, 2009
    Inventors: Kirk Hwang, Michael A. Moser, Spencer W. Ng
  • Publication number: 20090168231
    Abstract: According to one embodiment, disclosed herein is a disk drive that has a disk of discrete-track media (DTM) type. The DTM disk has servo regions. Each servo region has dividing grooves and non-servo data parts. Each dividing grooves extends along the centerline of any projecting region having a width larger than a prescribed value. Each non-servo data part suppresses reproduction noise. The disk drive has a read/write channel that includes a reproduced-signal processing unit. This unit reproduces servo data from each servo region.
    Type: Application
    Filed: March 4, 2009
    Publication date: July 2, 2009
    Applicant: KABUSHIKI KAISHA TOSHIBA
    Inventor: Yuji Sakai
  • Patent number: RE40955
    Abstract: A method and apparatus for storing position offset information not used for aligning the read element of an MR head with the centerline of written data, during a read operation. The skew or offset between the read and the write elements on a read head is first calibrated. The offset information then stored on one or more dedicated tracks of the disk. To accomplish this, the write element is aligned with the centerline of the dedicated track. The position offset information is then written in the data field of the dedicated track. During the power-on process, the read element is aligned with the centerline of the dedicated track and the position offset information may be retrieved by simply reading the information previously stored on the dedicated track.
    Type: Grant
    Filed: January 18, 2001
    Date of Patent: November 10, 2009
    Assignee: Samsung Electronics Co., Ltd.
    Inventors: Me Van Le, Jong-Ming Lin