Patents Examined by Dan I Davidson
  • Patent number: 6667841
    Abstract: In an apparatus for recording and regenerating data, a pass metric is calculated based on a likelihood converted from a previous calculation result iteratively until all pass metrics of the same data recorded many times on a recording medium are calculated, and then data recorded on the recording medium is decoded.
    Type: Grant
    Filed: February 21, 2001
    Date of Patent: December 23, 2003
    Assignee: Fujitsu Limited
    Inventors: Masakazu Taguchi, Akihiro Itakura, Akiyoshi Uchida
  • Patent number: 6665136
    Abstract: A method of recording information bits in a magnetic storage medium, the method comprising positioning a first conductor adjacent to a magnetic recording medium, the conductor having a width and a length, wherein a distance between the first conductor and the magnetic recording medium is less than or equal to the width and the length, and passing a first current through the conductor of sufficient magnitude to produce a magnetic field in the magnetic medium greater than one Tesla and having a magnetic field gradient in a cross track direction and a down track direction greater than 100 Oe/nm over a bit dimension. The thickness of the first conductor can be less than or equal to the distance between the first conductor and the magnetic recording medium. The current density in the conductor can be greater than 109 ampere/cm2, and the length of the conductor can be less than 100 nm. The current can be applied as one or more pulses in a predetermined clock cycle time.
    Type: Grant
    Filed: February 27, 2002
    Date of Patent: December 16, 2003
    Assignee: Seagate Technology LLC
    Inventors: Thomas William Clinton, Michael Allen Seigler, Robert Earl Rottmayer
  • Patent number: 6661591
    Abstract: A disk drive is disclosed comprising a disk, a head, and an actuator for actuating the head radially over the disk. The disk comprises a plurality of tracks, each track comprises a plurality of data sectors for storing data and a plurality of sector-reconstruction-interleave (SRI) sectors for storing redundancy data. The redundancy data stored in a selected one of the SRI sectors is generated in response to the data stored in an interleave of the data sectors corresponding to the selected one of the SRI sectors.
    Type: Grant
    Filed: January 31, 2001
    Date of Patent: December 9, 2003
    Assignee: Western Digital Technologies, Inc.
    Inventor: Michael S. Rothberg
  • Patent number: 6661610
    Abstract: The evaluation reference tape includes at least one recess formed on a magnetic recording layer of a magnetic tape by processing the magnetic recording layer. In the method and apparatus for manufacturing the magnetic recording layer, at least one recess is formed on the magnetic recording layer of the magnetic tape by a laser beam or laser beams in a visible region, an ultraviolet region or both which is incident on the magnetic recording layer of the magnetic tape while the magnetic tape is transported in the longitudinal direction. The evaluation reference tape can perform sensitivity correction of a dropout testing apparatus in accordance with a depth or size of a defect of the magnetic tape and evaluation of the recording/replaying system of the magnetic tape without destroying the evaluation reference tape itself. The method and apparatus can efficiently manufacture the evaluation reference tape.
    Type: Grant
    Filed: May 30, 2000
    Date of Patent: December 9, 2003
    Assignee: Fuji Photo Film Co., Ltd.
    Inventor: Osamu Iwasaki
  • Patent number: 6661593
    Abstract: In a servo information detection method and disk apparatus of the present invention, it is determined whether a pattern of detection bits, detected from a vicinity of a servo sync mark of a disk, matches with a given comparison bit pattern. A pattern of tolerance bits is changed based on a location of the disk where the servo sync mark is detected, so that the matching between the detection bit pattern and the comparison bit pattern is performed based on the changed tolerance bit pattern.
    Type: Grant
    Filed: July 10, 2001
    Date of Patent: December 9, 2003
    Assignee: Fujitsu Limited
    Inventors: Hiroshi Ashikaga, Nobuyuki Suzuki
  • Patent number: 6657802
    Abstract: A synchronization detector including a phase detector and a distance metric calculator. The phase detector uses the preamble readback signal to estimate the bit periods and outputs a signal indicative of this estimate. This signal is sued by the distance metric calculator to limit its search for the synchronization mark to every mth bit position, where m is a predetermined integer greater than one (1).
    Type: Grant
    Filed: November 5, 1999
    Date of Patent: December 2, 2003
    Assignee: Infineon Technologies Corporation
    Inventors: Jonathan Ashley, Isaiah Carew
  • Patent number: 6646820
    Abstract: A master information carrier (2) with an arranged pattern formed of a ferromagnetic film in a shape corresponding to information signals is superposed on a magnetic recording medium (1) and the arranged pattern formed of a ferromagnetic film is magnetized with a magnetizing head (6), thus transfer-recording the arranged pattern into the magnetic recording medium as a magnetized pattern. The magnetizing head includes an annular magnetic circuit with a gap, and a strength of a magnetic field applied to the master information carrier by magnetic flux leaking from portions other than the gap is set to be 20% or less of that of a magnetic field applied to the master information carrier by magnetic flux leaking from the gap. Quality deterioration due to various conditions during recording can be prevented and uniform recording with less variation depending on position on the magnetic recording medium is achieved.
    Type: Grant
    Filed: July 3, 2001
    Date of Patent: November 11, 2003
    Assignee: Matsushita Electric Industrial Co., Ltd.
    Inventors: Tatsuaki Ishida, Taizou Hamada, Hideyuki Hashi, Keizo Miyata, Yasuaki Ban, Hiromi Kita
  • Patent number: 6643085
    Abstract: An accessible count information which is the number of accessible times for recording medium is recorded on an additional recording dedicated area in the recording medium. Each time the recording medium is accessed, the accessible count information is subtracted and the value of remaining accessible count information is recorded in a non-recorded portion of the dedicated area. In this case, the access to the recording medium is controlled based on the minimum value of the accessible count information recorded in the dedicated area.
    Type: Grant
    Filed: November 19, 1999
    Date of Patent: November 4, 2003
    Assignee: Fujitsu Limited
    Inventors: Katsumi Shirai, Ichiro Anzai
  • Patent number: 6631043
    Abstract: An apparatus and method that allow for the compatibility of data-storage disks with disk drives is provided. In an illustrative implementation, an exemplary disk drive for use on data storage disks reads the control logic sector of cooperating data-storage disks for a compatibility indicator. If the disk is compatible the drive performs read/write operations. If the disk is incompatible, the indicator is overwritten to ensure compatibility. From there read/write operations are allowed. The processing may be realized by machine instructions present in a control circuit of the disk drive.
    Type: Grant
    Filed: February 5, 2001
    Date of Patent: October 7, 2003
    Assignee: Iomega Corporation
    Inventor: Ronald J. Stephens
  • Patent number: 6621649
    Abstract: The present invention relates to a preamplifier circuit comprising a plurality of amplifier stages coupled together and operable to consecutively amplify a signal associated with a head of a hard disk drive. The preamplifier circuit further comprises a power delivery circuit operably coupled to the amplifier stages and operable to provide power to the amplifier stages in a substantially concurrent manner when the hard disk drive is transitioning from a write state to a read state. In addition, the circuit comprises a control circuit operably coupled to the amplifier stages, and operable to activate at least two of the plurality of amplifier stages in a generally consecutive manner after the providing of power to the amplifier stages. In the above manner a saturation of an output of the preamplifier circuit is avoided by preventing substantially a propagation of glitches through the preamplifier circuit and providing for a substantially fast write-to-read transition time.
    Type: Grant
    Filed: November 10, 2000
    Date of Patent: September 16, 2003
    Assignee: Texas Instruments Incorporated
    Inventors: Hong Jiang, Indumini Ranmuthu
  • Patent number: 6611389
    Abstract: A method of determining a clearance between a magnetic transducer and a magnetic recording medium during a track seeking operation, the magnetic recording medium being moveable with respect to the transducer and including at least a test track and a reference track, which method comprises the steps of: at least partially erasing a predetermined area of the recording medium including at least one test track and one reference track; writing a first series of predetermined magnetic transitions along a spiral trace, formed by seeking operation of the transducer, on the at least one test track in the predetermined area; reading the test track and obtaining a pulse width of signals read back from the test track (test track pulse width) at a predetermined amplitude level; writing a further series of predetermined magnetic transitions identical to the first series on a reference track of the recording medium in the predetermined area; reading the reference track and obtaining, a pulse width of signals read back from
    Type: Grant
    Filed: October 7, 1999
    Date of Patent: August 26, 2003
    Assignee: Data Storage Institute
    Inventors: Bo Liu, Qisuo Chen
  • Patent number: 6611392
    Abstract: For the purpose of suppressing interruptions in data transfer to a minimum and carrying out optimum retry processing, the magnetic disk device of this invention includes: interface control means 1 for storing commands that have been received from a host computer in command queue 2; interface load detecting means 3 for detecting the interface load based on the total number of commands stored in command queue 2; load level conversion table 10 that takes the number of commands stored in command queue 2 as the index value; retry table 9 for storing contents of retry processing that correspond to each load level; and command executing means 4 for sequential fetching and executing of commands from command queue 2 and, when a retry is necessary, for obtaining from retry table 9 a content of retry processing that corresponds to the load level detected by interface load detecting means 3 and executing retry processing.
    Type: Grant
    Filed: November 5, 1999
    Date of Patent: August 26, 2003
    Assignee: TDK Corporation
    Inventor: Yoshihiro Hasebe
  • Patent number: 6606208
    Abstract: A master information carrier comprises a substrate whose surface has an embossed pattern corresponding to an information signal. At least a surface of the protruding portion of the embossed pattern is made of a ferromagnetic material. A method for writing an information signal into a sheet or disk magnetic record medium with a ferromagnetic thin film or coating is performed by putting the surface of the magnetic record medium into contact with the master information carrier so as to write a magnetized pattern corresponding to the embossed pattern of the master information carrier into the magnetic record medium.
    Type: Grant
    Filed: February 26, 2002
    Date of Patent: August 12, 2003
    Assignee: Matsushita Electric Industrial Co., Ltd.
    Inventors: Tatsuaki Ishida, Ryuji Sugita, Kiyokazu Tohma, Kazunari Yoshimoto, Keizou Miyata
  • Patent number: 6606209
    Abstract: A master information carrier comprises a substrate whose surface has an embossed pattern corresponding to an information signal. At least a surface of the protruding portion of the embossed pattern is made of a ferromagnetic material. A method for writing an information signal into a sheet or disk magnetic record medium with a ferromagnetic thin film or coating is performed by putting the surface of the magnetic record medium into contact with the master information carrier so as to write a magnetized pattern corresponding to the embossed pattern of the master information carrier into the magnetic record medium.
    Type: Grant
    Filed: March 26, 2002
    Date of Patent: August 12, 2003
    Assignee: Matsushita Electric Industrial Co., Ltd.
    Inventors: Tatsuaki Ishida, Ryuji Sugita, Kiyokazu Tohma, Keizou Miyata, Hiroshi Ryonai
  • Patent number: 6603618
    Abstract: A method and system for monitoring and/or adjusting the positioning of a magnetic tape using central control packets that are recorded to the tape is presented. Central control packets are used for adjusting the timing of the read head signal over the tape, adapting the reel count to that of the drive at the time the tape was recorded, and monitoring filemarks for logical tape positioning.
    Type: Grant
    Filed: November 16, 1998
    Date of Patent: August 5, 2003
    Assignee: Exabyte Corporation
    Inventors: Richard McAuliffe, Frederick G. Munro, Paul Newsome, Thomas E. Zaczek
  • Patent number: 6600614
    Abstract: An apparatus, modules, means, and computer readable media for and a method of logging critical events to a critical event log storage area on a disc in a disc drive are disclosed. The disc drive having a data storage disc is operably connected to a host computer. The data communication between the host computer and the disc drive is established via a disc drive interface. The disc drive interface may be an ATA disc drive interface. A power-on operational status of the disc drive with the host computer is determined. Then a critical event is determined without a host computer intervention. A set of critical events are predefined and stored in the firmware of the disc drive. The critical event can be monitored and logged either during an on-line data collection mode or an off-line data collection mode. During the off-line data collection mode, the firmware performs off-line scan of the disc drive in the background.
    Type: Grant
    Filed: June 25, 2001
    Date of Patent: July 29, 2003
    Assignee: Seagate Technology LLC
    Inventors: Thomas R. Lenny, James Arthur Herbst, Jonathan William Haines
  • Patent number: 6594716
    Abstract: An integrated data storage control system provides, in a single integrated circuit, RDC, servo logic, ATA interface, microprocessor, and other formerly discrete components in one highly integrated system design. The integrated circuit is rendered using a single integrated circuit technology type (e.g., digital CMOS) for all components. Analog and digital circuits are combined in such a way as to eliminate or reduce noise or interference in digital circuits from analog circuit components. Individual elements may have their outputs and inputs MUXed together such that individual elements can be selectively switched (during testing modes) such that the integrated circuit emulates or behaves in the same or similar manner as one of the prior art components. The present invention may be applied to magnetic hard disk drives (HDDs) or other types of storage devices such as floppy disk controllers, optical disk drives (e.g., CD-ROMs and the like), tape drives, and other data storage devices.
    Type: Grant
    Filed: June 28, 2001
    Date of Patent: July 15, 2003
    Assignee: Cirrus Logic, Inc.
    Inventors: Siamack Nemazie, Kaushik Popat, Balaji Virajpet, William R. Foland, Jr., Roger McPherson, Maoxin Wei, Vineet Dujari, Shiang-Jyh Chang
  • Patent number: 6594103
    Abstract: A servo control system and method controls systems at least partially on the basis of an observable variable that has an absolute value functional relationship with the controlled variable and does not change sign for positive and negative variations from a nominal value. The control system and method find particularly advantageous application in magnetic storage hard disk drive systems because the system allows such hard disk drives to perform servo operations such as track following on the basis of the data signals being read from the track. A particularly useful source of the absolute value observable variable is a read channel chip that performs decoding of data recovered from the disk. Error measures are developed as the data signals from the disk are processed and decoded, including error measures from the slicer used in an adaptive equalization process and from the data decoder, which may be a Viterbi decoder.
    Type: Grant
    Filed: November 12, 1999
    Date of Patent: July 15, 2003
    Assignee: Acorn Technologies, Inc.
    Inventors: Alvin M. Despain, R. Stockton Gaines
  • Patent number: 6594096
    Abstract: Embodiments of the present invention illustrate various configurations of a channel-to-controller interface. In one embodiment, width of symbols crossing the interface is fixed, as is the clock rate. In other embodiments, the symbol width is variable, and the clock rate is also varied based upon the size of the interface symbol width and the operation of the channel.
    Type: Grant
    Filed: June 28, 2001
    Date of Patent: July 15, 2003
    Assignee: Seagate Technology LLC
    Inventors: Kenneth R. Burns, Srinivas Maddali, Jimmie Ray Shaver, Bernardo Rub, Peter I. Vasiliev, Wuping Chen, Kavi Alptekin, Gary W. Reininga, Robert D. Cronch, Clifton J. Williamson
  • Patent number: 6590727
    Abstract: A master information carrier comprises a substrate whose surface has an embossed pattern corresponding to an information signal. At least a surface of the protruding portion of the embossed pattern is made of a ferromagnetic material. A method for writing an information signal into a sheet or disk magnetic record medium with a ferromagnetic thin film or coating is performed by putting the surface of the magnetic record medium into contact with the master information carrier so as to write a magnetized pattern corresponding to the embossed pattern of the master information carrier into the magnetic record medium.
    Type: Grant
    Filed: December 21, 2001
    Date of Patent: July 8, 2003
    Assignee: Matsushita Electric Industrial Co., Ltd.
    Inventors: Tatsuaki Ishida, Ryuji Sugita, Kiyokazu Tohma, Kazunari Yoshimoto, Keizou Miyata