Patents Examined by Dan I Davidson
  • Patent number: 7012778
    Abstract: In the start up of the magnetic disk apparatus, the phase relation between servo information numbers recorded on the magnetic disk 15 in advance and the eccentricity of the magnetic disk is learned. In the positioning of the magnetic head, a signal generated by multiplying, by a weight coefficient, a sine wave or a cosine wave the phase the revolution frequency of the magnetic disk is fed forward as an eccentricity control amount, whereby the eccentricity is compensated.
    Type: Grant
    Filed: October 4, 2002
    Date of Patent: March 14, 2006
    Assignee: Matsushita Electric Industrial Co., Ltd.
    Inventor: Norio Shigematsu
  • Patent number: 7012771
    Abstract: A method of defining such a storage format in multiple data storage devices, each data storage device having a plurality of storage media and a plurality of corresponding data transducer heads, each transducer head for recording on and playback of information from a corresponding storage medium in at least one zone, wherein each zone includes a plurality of concentric tracks for recording on and playback of information.
    Type: Grant
    Filed: January 26, 2002
    Date of Patent: March 14, 2006
    Assignee: Maxtor Corporation
    Inventors: Saeed Asgari, Mathew Vea, George Iszlai
  • Patent number: 7006317
    Abstract: A tape drive for use with magnetic tapes includes a housing for receiving a magnetic tape having multiple parallel tracks, and a tape head for reading and writing the parallel tracks of the magnetic tape. A plurality of partial response maximum likelihood (PRML) equalization/detection channels are provided for processing the data signals to determine the data stream for each data signal. The plurality of PRML equalization/detection channels includes at least one PRML equalization/detection channel pre-assigned to each track. The plurality of PRML equalization/detection channels further includes at least one floating PRML equalization/detection channel dynamically assignable on an as-needed basis. The invention also contemplates an ASIC, a generic drive, and a PRML method.
    Type: Grant
    Filed: December 5, 2003
    Date of Patent: February 28, 2006
    Assignee: Storage Technology Corporation
    Inventors: Mark Hennecken, Richard A. Gill, Keith Boyer
  • Patent number: 7002766
    Abstract: A rotating storage apparatus is provided for high recording reliability in an environment in which a shock or vibration exists. Provided are means for outputting a shock out signal (SO) if an output from an acceleration sensor exceeds a predetermined threshold, a latch circuit 21 for outputting a latch signal at high level during a predetermined write inhibit period after the shock out signal (SO) is input, and a write gate signal (WG) which goes high when a write is enabled. A write enable signal is generated by an AND circuit 23 having a NOT output of the latch signal as well as the write gate signal WO as its inputs.
    Type: Grant
    Filed: March 3, 2004
    Date of Patent: February 21, 2006
    Assignee: Hitachi Global Technologies Netherlands, B.V.
    Inventors: Masashi Kisaka, Yutaka Ozawa, Kenji Toga
  • Patent number: 6999256
    Abstract: A method of measuring the degree of thermal pole tip protrusion (TPTP) of a magnetic head and controlling a recording current in consideration of the degree of TPTP, in relation to a hard disk drive includes measuring the rate of errors contained in data by performing writing and reading operations while changing the level of an overshoot current (OSC), detecting a minimum error rate and a maximum error rate while changing a range of the OSC, and determining the degree of TPTP by measuring the difference between the minimum error rate and the error rate at the maximum OSC.
    Type: Grant
    Filed: December 12, 2003
    Date of Patent: February 14, 2006
    Assignee: Samsung Electronics Co., Ltd.
    Inventors: Jong-Yoon Kim, Chang-Dong Yeo
  • Patent number: 6999257
    Abstract: A disk drive of a perpendicular magnetic recording type uses a double-layered disk. The disk has a plurality of tracks for storing data and a non-recording region (GB area) between tracks. Not a DC magnetized pattern but an AC magnetized pattern or a random magnetized pattern is recorded in the GB area. With this structure, it is possible to prevent an influence of magnetic disturbance due to a DC magnetic field on the surface of the disk.
    Type: Grant
    Filed: January 31, 2002
    Date of Patent: February 14, 2006
    Assignee: Kabushiki Kaisha Toshiba
    Inventor: Akihiko Takeo
  • Patent number: 6987632
    Abstract: To account for head misplacement while servowriting, conditional writing and/or trimming of servo information can be used. Conditional servowriting allows servowriting to be disabled when it is determined that servo information will not be written and/or trimmed at a desired location or within a threshold distance of a desired location. For example, if a distance between a write element or a predicted location of servo information and a desired location of the servo information or write element exceeds a threshold, writing and/or trimming can be inhibited. Servowriting can be resumed when it is determined that servo information will be written or trimmed at a desired location or within a threshold distance of a desired location. A servowriting step or pass is not re-started when the threshold is exceeded and those wedges for which servo information was not writtten and/or trimmed can be attempted during subsequent revolutions of the rotatable storage medium.
    Type: Grant
    Filed: April 6, 2004
    Date of Patent: January 17, 2006
    Assignee: Matsushita Electric Industral Co., Ltd.
    Inventor: Richard M. Ehrlich
  • Patent number: 6985321
    Abstract: A head suspension assembly having a magnetic head, an arm which is supported so as to rotate, a suspension having one end which is fixed to an end of the arm and an other end which mounts the magnetic head, a nonvolatile memory which is mounted on the suspension assembly, and stores control parameters of the magnetic head, a connecting terminal which is mounted to the arm, and a signal transmission line which electrically connects the connecting terminal to the nonvolatile memory and the magnetic head. The connecting terminal enables transmission of signals at least one of to and from the head suspension assembly, the nonvolatile memory and the magnetic head.
    Type: Grant
    Filed: March 9, 2004
    Date of Patent: January 10, 2006
    Assignee: Hitachi, Ltd.
    Inventor: Akira Osaki
  • Patent number: 6985318
    Abstract: A magnetic recording process generally including the steps of determining an initial magnetization direction of a magnetic recording medium, and selectively applying a magnetic field to the magnetic recording medium along an axis substantially perpendicular to an axis of the initial magnetization direction of the recording medium. The magnetic field is selectively applied for a period of time sufficient to switch the magnetization of the magnetic recording medium from its initial magnetization direction to a final magnetization direction substantially anti-parallel to the initial magnetization direction. Typically, the initial and final magnetization directions will be along an easy axis of magnetization of the magnetic recording medium.
    Type: Grant
    Filed: June 3, 2003
    Date of Patent: January 10, 2006
    Assignee: Seagate Technology LLC
    Inventors: Thomas W. Clinton, Thomas M. Crawford
  • Patent number: 6985314
    Abstract: A method of forming a magnetic transition pattern in a magnetic material by contact printing comprises steps of providing a stacked assembly including a workpiece including a surface comprised of the magnetic material including a plurality of initialized, unidirectionally aligned magnetic domains, and a high saturation magnetization stamper having an imprinting surface in intimate contact with the workpiece surface, the imprinting surface comprising a plurality of projections and depressions arranged in a pattern corresponding to the magnetic transition pattern to be formed in the magnetic material, and selectively magnetically re-aligning the initialized, unidirectionally aligned magnetic domains by placing the assembly in a fixed gap contact printing apparatus including a magnet means having a pair of spaced-apart, stationary magnetic poles providing an oppositely directed, uniform intensity, unidirectional re-alignment magnetic field.
    Type: Grant
    Filed: May 9, 2003
    Date of Patent: January 10, 2006
    Assignee: Seagate Technology LLC
    Inventor: Li-Ping Wang
  • Patent number: 6985315
    Abstract: A magnetic disk evaluation apparatus includes an evaluation head for evaluating a magnetic disk, and a support member for supporting the evaluation head. The support member supports the evaluation head in a state where a flying surface of the evaluation head and a surface of a magnetic disk make a flying pitch angle of 95 ?rad or more.
    Type: Grant
    Filed: January 27, 2002
    Date of Patent: January 10, 2006
    Assignee: Fujitsu Limtied
    Inventors: Toru Yokohata, Yoshiharu Kasamatsu, Satoru Momose, Takayuki Yamamoto
  • Patent number: 6980386
    Abstract: A disc drive has transducers supported by an actuator to fly proximate data tracks on surfaces of rotating information storage discs. Each of the discs is partitioned into concentric regions. A control system arranges the deposition of data in write operations to the tracks on the disc surfaces, as data is written to the discs, such that the data is sequentially organized both on the tracks and within each of the regions. The control system writes data from a track adjacent a first region boundary in a first direction to a second region boundary until all tracks in a region are full. The control system executes a head switch between adjacent surfaces of the discs. The write sequence is repeated in each adjacent region until all regions are full. The resulting trapezoidal serpentine pattern of actuator movement and head switches is repeated until all of the write operations are complete.
    Type: Grant
    Filed: June 4, 2003
    Date of Patent: December 27, 2005
    Assignee: Seagate Technology LLC
    Inventors: Joseph L Wach, Khalil B Dizaji
  • Patent number: 6963462
    Abstract: For the purpose of providing technique by which even when large skew of a disk or a head occurs due to a thermal shock, an outside shock, or the like, a servo signal area is not extended, and a performance loss caused by head change is not produced, a servo detection control system according to the present invention comprises: a learning means by head change including a servo sector interval measuring unit for measuring an interval of servo signal areas, which may occur at the time of head change among a plurality of heads; a time difference calculating unit for calculating head-change time difference from a value measured by the servo sector interval measuring unit; and a time difference storage unit for storing a result of calculation made by the time difference calculating unit; and a compensation and control means for compensating start timing of servo detection after head change using a stored value of the time difference storage unit.
    Type: Grant
    Filed: February 20, 2002
    Date of Patent: November 8, 2005
    Assignee: Hitachi Global Storage Technologies Japan, Ltd.
    Inventor: Naoki Satoh
  • Patent number: 6958873
    Abstract: Apparatus for transferring data from a host computing system to one or more magnetic tape storage devices or the like, the apparatus comprising input apparatus for receiving data and converting it into codeword pairs in a format suitable for storage on the tape, a write head for writing the codeword pairs in codeword quad (CQ) sets of 2×8 codeword pairs to the tape, a read head for reading back data written to the tape and transferring the read data to an error checking block which is arranged to generate a negative output if a codeword pair includes an error and/or more than a predetermined number of errors, and control apparatus for causing the write head to rewrite a CQ set to the tape in response to a negative output from the error checking block, the control apparatus being configured or configurable to rewrite a CQ set to the tape until all of the codeword pairs (or CQ's) in that CQ set are written without error (or less than a predetermined number of errors) during the same rewrite, thereby maximizing
    Type: Grant
    Filed: July 31, 2001
    Date of Patent: October 25, 2005
    Assignee: Hewlett-Packard Development Company, L.P.
    Inventor: Jorge Antonio Sved
  • Patent number: 6954317
    Abstract: When a master medium and a slave medium are brought into close contact and a transfer magnetic field is applied thereto to perform magnetic transfer, the leakage magnetic field intensity of the transfer magnetic field is regulated to within a permissible range, making possible the transfer of an exact magnetic pattern. After a magnetic field is applied to the slave face in the track direction thereof to initially magnetize the slave medium in the track direction, the master medium and the slave medium are brought into close contact. When applying a transfer magnetic field in the track direction of the slave face to perform a magnetic transfer, the magnetic field intensity component in the direction opposite that in which the transfer magnetic field is to be applied is regulated to less than or equal to ½ the magnetic coercive force Hcs of the slave medium over the entire slave surface.
    Type: Grant
    Filed: January 31, 2002
    Date of Patent: October 11, 2005
    Assignee: Fuji Photo Film Co., Ltd.
    Inventors: Masashi Aoki, Kazunori Komatsu, Masakazu Nishikawa, Junichi Nakamikawa
  • Patent number: 6954320
    Abstract: A hard disk drive and process of controlling the drive by adjusting disk drive parameters in accordance with ambient temperature. Various parameters affected by thermal variation are controlled to automatically adjust those values in order to compensate for changes in ambient temperature when an environment where a hard disk drive is installed changes, thereby allowing the hard disk drive to continuously operate with optimal performance. Those parameter, which are sensitive to the temperature of a hard disk drive, can be modified or controlled using the relationship therebetween in accordance with the current ambient temperature, thereby preventing any deterioration of the performance of the hard disk drive, even when temperature at the burn-in process and the current ambient temperature are different from each other.
    Type: Grant
    Filed: February 12, 2002
    Date of Patent: October 11, 2005
    Assignee: Samsung Electronics, Co., Ltd.
    Inventor: Won-choul Yang
  • Patent number: 6950258
    Abstract: In a head positioning method and device in which the position of servo signals between heads is not uniform, it is aimed to reduce the time taken to find the servo signals when heads are switched. A storage disk device comprises storage disks with the servo signals, a plurality of heads that read the information from the storage disks, an actuator that moves the heads, and a control circuit that positions the heads based on the servo signals read from the storage disks by a selected head. This control circuit includes a synchronization circuit that, in response to a head switching cue, synchronizes the time of a servo gate signal (of the head to which switching is directed) for detecting a servo signal with the time of the servo signal read by the head to which switching is directed, and a processing circuit that reads the servo signal for the head in response to the synchronized detection signal and positions the head in response to the servo signal read.
    Type: Grant
    Filed: March 8, 2001
    Date of Patent: September 27, 2005
    Assignee: Fujitsu Limited
    Inventor: Kazuhiko Takaishi
  • Patent number: 6947238
    Abstract: A bias circuit for a magneto-resistive head having a bias current output circuit for flowing a bias current through a magneto-resistive head, and a feedback circuit for controlling the bias current from a bias current output circuit by detecting voltage variation across the magneto-resistive head so that a voltage across the magneto-resistive head becomes a predetermined value. The bias current output circuit comprises a regulating circuit for regulating an operation of the bias current output circuit in the bias current output circuit, a control circuit for controlling the regulating circuit to be in a predetermined condition, and a switching circuit for switching a read/write condition for activating the control circuit for the regulating circuit in a non-read condition of the magneto-resistive head. The regulating circuit includes an oscillation suppressing capacitor; and the control circuit for the regulating circuit is a charging circuit for the oscillation suppressing capacitor.
    Type: Grant
    Filed: June 3, 2003
    Date of Patent: September 20, 2005
    Assignee: Sony Corporation
    Inventors: Kazue Takayoshi, Michiya Sako
  • Patent number: 6937430
    Abstract: Friction existing between any two surfaces having relative motion is nonlinear, multiform, and is difficult to model. Nonlinear friction in the actuator pivot of a hard disk drive (HDD) limits the low frequency gain, which prevents the system positioning accuracy from further improvement. This problem is much more pronounced for the severe nonlinearity at the micrometer level. The conventional two-mode proximate time optimal servomechanism (PTOS) is inadequate for immediate future hard disk drives because of the existence of restrictions in the particular design approach. A triple-mode control scheme, and its variations, as presented herein, include (a) a proximate time-optimal controller (PTOC) having a relatively large output is used for track seeking, (b) a robust compensator having a relatively small output is used for track following to compensate for friction and other nonlinearities, and (c) a bridging (connection) control to guarantee the continuity of the control signals.
    Type: Grant
    Filed: January 10, 2001
    Date of Patent: August 30, 2005
    Assignee: National University of Singapore
    Inventors: Shuzhi Ge, Yaolong Lou, Tong Heng Lee, Chun-Hung Tony Huang, Teck Seng Low
  • Patent number: 6930845
    Abstract: Method and apparatus for recording data on a magnetic recording medium and writing data to a computer bus in which the data is divided into words of a predetermined length, a signal is generated for each data word, having an amplitude which is representative of the value of the data word, and this signal is then recorded to the magnetic recording medium or written to the computer bus. Complementary method and apparatus is provided for reading the data from the magnetic recording medium and the computer bus.
    Type: Grant
    Filed: September 28, 2001
    Date of Patent: August 16, 2005
    Assignee: Trix SRT Limited
    Inventor: Phil Haylor