Patents Examined by Dan I Davidson
  • Patent number: 6809893
    Abstract: A storage system has a storage medium, a head, and a control unit for carrying out refresh processing. A refresh operation extracts data that needs to be refreshed by measuring the read-out output level of target data. Then, data requiring refresh is re-recorded to the storage medium by the head. Because an actual data level is observed, it is possible to accurately detect refresh target data, and because there is no need for a reference area, it is possible to prevent a reduction in storage capacity.
    Type: Grant
    Filed: January 26, 2001
    Date of Patent: October 26, 2004
    Assignee: Fujitsu Limited
    Inventors: Takuya Uzumaki, Kazumasa Shimoda, Hiroto Takeshita, Atsushi Tanaka
  • Patent number: 6804074
    Abstract: A PLL circuit functioning as a clock recovery circuit in a tape recording and playback apparatus employing the PRML method has a level determining circuit for detecting that head output level (signal level) is at or lower than a certain level during track crossing for a high-speed search, and effects a hold on a loop filter according to a level determination output to thereby hold PLL operation, whereby the PLL behavior is not disturbed by a noise component occurring during track crossing. Thus, it is possible to stabilize search operation and increase the design margin.
    Type: Grant
    Filed: May 23, 2001
    Date of Patent: October 12, 2004
    Assignee: Sony Corporation
    Inventors: Norio Shoji, Junkichi Sugita, Kimimasa Senba, Toshihiro Kawakubo
  • Patent number: 6795263
    Abstract: In a high-frequency impedance type magnetic head having high impedance and capable of efficiently detecting a change in impedance, an electrically conductive metal film is sandwiched between two soft magnetic films, and the two soft magnetic films form a portion of a magnetic path. The thickness of one soft magnetic film is smaller than the thickness of the other soft magnetic film. The electrically conductive metal thin film has a pair of electrodes at respective ends thereof, to which are connected an oscillator for applying a high frequency carrier signal to the electrodes and a high frequency amplifier having a demodulator circuit. Further, an electrically conductive metal film winding is provided, and a DC current is applied to the electrically conductive metal film winding at the time of reproduction, while on the other hand, a signal current is applied to the electrically conductive metal film winding at the time of recording.
    Type: Grant
    Filed: October 1, 2002
    Date of Patent: September 21, 2004
    Assignee: Matsushita Electric Industrial Co., Ltd.
    Inventors: Akio Kuroe, Sayuri Muramatsu, Hirotsugu Fusayasu, Akio Murata
  • Patent number: 6781778
    Abstract: The invention combines the benefits of sectored servo data with the benefits of time-based servo data. Recording media such as magnetic tape, magnetic disks, optical tape and optical disks can store servo data in a time-based sectored servo format.
    Type: Grant
    Filed: July 16, 2001
    Date of Patent: August 24, 2004
    Assignee: Imation Corp.
    Inventors: Richard W. Molstad, Douglas W. Johnson, Durkee B. Richards
  • Patent number: 6775080
    Abstract: This invention discloses a data access system for access data stored on a flat medium. The data access system includes a pickup head rotating over the flat medium. The data access system further includes at least one stepping motor for discretely moving the flat medium substantially along at least one lateral direction perpendicular to a rotational axis of the pickup head. The data access system further includes a closed loop control mechanism for controlling the stepping motor for allowing the pickup head to read data from a servo segment on the flat medium. The controller further includes an open loop control mechanism for rotating the pickup head for reading data from and writing data to a data segment disposed right next to the servo segment on the flat medium.
    Type: Grant
    Filed: January 29, 2001
    Date of Patent: August 10, 2004
    Assignee: DCARD, Inc.
    Inventors: Francis K. King, Jeffrey F. Liu
  • Patent number: 6771443
    Abstract: A propagating method is provided in which timing and servo sector information is propagated throughout a data storage media that initially contains only a guide pattern. The method uses an offset between the write element and the read element in a read/write head to position and propagate the timing information. In addition, a method for circumferentially aligning timing and servo sector information is disclosed that utilizes a time delay to position the propagated timing and servo sector information. Another method for attenuating timing errors during timing and servo sector propagation to a data storage media is disclosed. Timing errors are attenuated through the use of phase locked loop circuit and measurement of the phase error detected between different tracks on the data storage media. Apparatuses implementing the methods including a storage device readable by a computer system that implements the methods are provided.
    Type: Grant
    Filed: July 26, 2001
    Date of Patent: August 3, 2004
    Assignee: Seagate Technology LLC
    Inventors: Gabor Szita, Lawrence Matthias Bryant, Karl Arnold Belser, Alan Fennema
  • Patent number: 6771446
    Abstract: The present invention includes a method and apparatus to write and read copy protected data on a disc drive storage system using a servo wedge.
    Type: Grant
    Filed: February 28, 2001
    Date of Patent: August 3, 2004
    Assignee: Seagate Technology LLC
    Inventor: Gayle L. Noble
  • Patent number: 6768603
    Abstract: A method for write-precompensating a waveform for magnetically recording a waveform on a magnetic medium is disclosed. A user data stream is encoded into an encoded data stream so that the encoded data stream has no tribits and no consecutive dibits. No delay is applied to a first transition of a dibit of the encoded data stream. An isolated transition of the encoded data stream is delayed by a first predetermined amount of time. The second transition of a dibit of the encoded data stream is delayed by a second predetermined amount of time, such that the second predetermined amount of time is substantially twice the first predetermined amount of time. Preferably, the encoded data stream satisfies a predetermined run length limited (RLL) k− constraint of k=13 and a predetermined twins t-constraint of t=15. In one embodiment, the encoded data stream is encoded by a block code at rate 8:10. In another embodiment, the encoded data stream is encoded by a block code at rate 16:19.
    Type: Grant
    Filed: March 7, 2001
    Date of Patent: July 27, 2004
    Assignee: International Business Machines Corporation
    Inventors: Roy Daron Cideciyan, Evangelos Stavros Eleftheriou, Brian Harry Marcus, Dharmendra Shantilal Modha, Radley Wahl Olson
  • Patent number: 6768607
    Abstract: A disk drive comprises an actuator servo control system including at least one disk, an actuator structure comprising at least transducer head for writing and/or reading data from the disk and providing a transducer head position error signal (PES), and a servo compensator applying a servo control algorithm to the PES to produce a servo control signal. An adaptive elliptic notch filter controller is adapted to analyze the PES for a transducer head at a disk track radii, identify resonant disturbances present in the PES, select two adjacent resonant disturbances having first and second frequencies, ascertain coefficients of at least a fourth-order elliptic notch filter transfer function having first and second zero-notches with frequencies substantially at the first and second resonant frequencies, apply the at least fourth-order elliptic notch filter transfer function with the ascertained coefficients in the servo system to thereby substantially attenuate the selected adjacent resonant disturbances.
    Type: Grant
    Filed: August 22, 2001
    Date of Patent: July 27, 2004
    Assignee: Hitachi Global Storage TEchnologies Netherlands B.V.
    Inventors: Hal Hjalmar Ottesen, Gordon James Smith
  • Patent number: 6762896
    Abstract: The storage media recording/writing system includes a media drive circuit, a head retaining means, a head moving means, a head drive circuit, a signal processing circuit, and a controller to control these. The head drive circuit possesses a first semiconductor integrated circuit having an amplifier that amplifies the read signal from the head, and a second semiconductor integrated circuit placed between the first semiconductor integrated circuit and the signal processing circuit, which has a circuit that receives write data from the signal processing circuit and generates a drive signal to drive a write head. Further, the first semiconductor integrated circuit is mounted on a part near the front of the head retaining means, and the second semiconductor integrated circuit is installed on the side of the moving means.
    Type: Grant
    Filed: July 12, 2001
    Date of Patent: July 13, 2004
    Assignee: Hitachi, Ltd.
    Inventors: Hiroyasu Yoshizawa, Yoichiro Kobayashi, Toshio Shinomiya, Noriyuki Fujii, Masaki Yoshinaga
  • Patent number: 6762894
    Abstract: A head apparatus which is tough against disturbing noise and superior in the S/N ratio and which can cope with an increase of the capacity of a recording medium is disclosed. A first playback amplifier for amplifying the playback signal of a MR head and a register circuit for setting the bias current to the MR head are formed as a COS IC. The COS IC is mounted on a suspension together with the MR head. A feeble playback signal outputted from the MR head is amplified by the first playback amplifier once and then transmitted to a mother IC over a pair of signal lines. The amplified playback signal is tough against disturbing noise during transmission.
    Type: Grant
    Filed: June 28, 2001
    Date of Patent: July 13, 2004
    Assignee: Sony Corporation
    Inventors: Keiji Narusawa, Norio Shoji
  • Patent number: 6762895
    Abstract: A signal is read out from a two-layered perpendicular magnetic recording medium by a composite head formed from a single-pole perpendicular recording head and magnetoresistance effect type reproduction head. The read-out signal is amplified by a head amplifier, passed through a low-pass filter, and converted into a digital signal by an analog/digital converter. A DC restoring circuit restores a DC component removed by the head amplifier using the output signal from the analog/digital converter. An adder adds the restored DC component to the output signal from the analog/digital converter, thereby restoring the head output terminal signal. A servo demodulation circuit generates a position error signal on the basis of the restored signal.
    Type: Grant
    Filed: August 23, 2001
    Date of Patent: July 13, 2004
    Assignee: Kabushiki Kaisha Toshiba
    Inventor: Koji Osafune
  • Patent number: 6760177
    Abstract: In an essentially flat contour linear tape recording head, a nominal tape wrap angle exists at which reading signals from the magnetic tape ceases and/or commences. This nominal tape wrap angle can be easily determined by monitoring a prerecorded signal, such as the servo track signal, while the tape wrap angle is adjusted. When the signal ceases (or starts, depending upon the direction of adjustment) an initial position of the tape movement control device relative to the tape wrap angle is identified. At this initial position it is known that the tape wrap angle is at its nominal value, such as approximately 0.1°. Thereafter, the tape movement control device can be knowingly adjusted with a calibrated indicator to accurately and quickly achieve a desired final tape wrap angles.
    Type: Grant
    Filed: August 23, 2001
    Date of Patent: July 6, 2004
    Assignee: International Business Machines Corporation
    Inventor: Robert Glenn Biskeborn
  • Patent number: 6760184
    Abstract: A disk drive system has a servo pattern with bursts that are recorded without multiple passes per burst and without trimming, so that the servo pattern bursts have the same width as the data tracks. The servo write steps occur in partial data track pitch (DTP) increments. A magneto-resistive (M-R) head is used to both record the servo pattern and transduce it. In a two-frequency system, relative gain calibration is performed using AGC circuitry to first calibrate one frequency and then the other. The resulting servo position error sensing (PES) signal has improved linearity and is simpler to write.
    Type: Grant
    Filed: February 7, 2000
    Date of Patent: July 6, 2004
    Assignee: Hitachi Global Storage Technologies
    Inventor: Earl Albert Cunningham
  • Patent number: 6757117
    Abstract: Control circuitry for a disk drive system that has improved data detection by using log likelihood values and erasure pointers. The control circuitry is comprised of a log likelihood modification system and a decoder. The log likelihood modification system receives log likelihood values that represent data and erasure pointers. The erasure pointers point to at least one of the log likelihood values that has been corrupted in some manner. The log likelihood modification system sets the log likelihood values, that the erasure pointer points to, to an error value to generate modified log likelihood values. The log likelihood modification system transfers the modified log likelihood values to the decoder. The decoder processes the modified log likelihood values based on code constraints to generate estimated log likelihood values. The decoder then decodes the data from the estimated log likelihood values.
    Type: Grant
    Filed: August 24, 2001
    Date of Patent: June 29, 2004
    Assignee: Cirrus Logic, Inc.
    Inventor: Jay N. Livingston
  • Patent number: 6754022
    Abstract: The present invention provides techniques for generating an intense magnetic pulse very quickly. The present invention includes a device that drives high current through a write head, which generates a burst of magnetic flux that in turn generates a high-intensity fringing field. To rapidly build up the current through the write head, the write head is coupled to a high voltage source. A switching circuit prevents current from flowing in the write head. In response to a signal from a control circuit, the switching circuit provides a path for current to flow through the write head. Current flow through the write head rises rapidly, which causes a burst of magnetic flux and generates a high-intensity magnetic fringing field. The high-intensity fringing field may be used to write to a magnetic medium.
    Type: Grant
    Filed: July 16, 2001
    Date of Patent: June 22, 2004
    Assignee: Imation Corp.
    Inventor: Richard W. Molstad
  • Patent number: 6754021
    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 WG as its inputs.
    Type: Grant
    Filed: March 19, 2001
    Date of Patent: June 22, 2004
    Assignee: International Business Machines Corporation
    Inventors: Masashi Kisaka, Yutaka Ozawa, Kenji Toga
  • Patent number: 6754018
    Abstract: A method of correcting erroneous data due to thermal asperity and a device therefor is provided. A magnetic disc device equipped with such error correction device is also provided. The correction device includes a comparator for comparing data signal reproduced from a magnetic disc with a predetermined threshold signal; and circuitry for generating an error signal based on the signal output from the comparator and the data signal. Using the error signal, the location and the length of erroneous data included in the data signal are determined. The erroneous data may be corrected, irrespective of the length thereof, by selective use of hardware ECC on the fly and software ECC. An alternative error signal may be generated by a technique based on the run lengths of the data.
    Type: Grant
    Filed: July 8, 1998
    Date of Patent: June 22, 2004
    Assignee: Fujitsu Limited
    Inventor: Tsuyoshi Takahashi
  • Patent number: 6751037
    Abstract: Herein is disclosed a method and apparatus for optimizing a disc drive for audio-visual data storage and retrieval by responding to a certain read-time error in a manner that preserves data flow. In response to a read-time error in which a synchronization field associated with a given sector on a disc is undetected, the disc drive responds by transferring a fill pattern of bits or a return status to the host microprocessor so as to indicate the error, and allow the disc drive to continue attempting to seek subsequent synchronization fields. The fill pattern of bits may be chosen so as to minimize the negative impact of processing the unread data by down-stream audio-visual equipment. The aforementioned behavior is a departure from the traditional sequential paradigm of a conventional disc drive. The new behavior preserves data flow, a quality important to audio-visual drives.
    Type: Grant
    Filed: June 23, 2000
    Date of Patent: June 15, 2004
    Assignee: Seagate Technology LLC
    Inventors: Jonathan Williams Haines, Brian John Higley
  • Patent number: 6747825
    Abstract: A disc drive includes a base and a disc rotatably attached to the base. The disc drive is formatted by obtaining a list of defective sector entries, determining a first location of selected information based on skipping the defective sectors within the list of defective sector entries, and calculating a second location for selected information. At least one sector to skip is added before the second location of selected information to move the selected information from the first position to the second position. The added sectors may be designated as defective sectors. By adding the at least one sector to skip, the second position of the information is moved or slipped.
    Type: Grant
    Filed: May 24, 2000
    Date of Patent: June 8, 2004
    Assignee: JPMorgan Chase Bank, as Collateral Agent
    Inventors: Wei Loon Ng, Beng Wee Quak, YongPeng Chng, Wesley Wing Hung Chan, Patrick Tai Heng Wong