Patents Represented by Attorney, Agent or Law Firm Paik Saber
  • Patent number: 7031096
    Abstract: Disclosed is a data storage device, a servo control method, and a program to reduce effects of a resonance frequency of an actuator or the like without reduction in servo control performance. A band-pass filter comprising a first all pass filter (APF) and a second adder, a second APF, and a multiplier are used to detect how much a current resonance frequency of the actuator deviates from a set value of a center frequency of the first APF, and based on a result of the detection, the center frequency of the first APF is properly adjusted. The adjustment of the center frequency of first APF enables a center frequency of a notch filter comprising the first APF and a first adder to be automatically approximated to a current resonance frequency of the actuator.
    Type: Grant
    Filed: August 20, 2003
    Date of Patent: April 18, 2006
    Assignee: International Business Machines Corporation
    Inventor: Masashi Kisaka
  • Patent number: 6754026
    Abstract: A tape transport servo system and method that do not make use of tachometers and/or encoders to derive tape velocity and position are provided. The tape transport servo system and method derive velocity and position of the tape from a primary and direct manner and also a secondary or alternative manner, especially when the primary or direct manner cannot be used. The tape transport servo system and method control a tape drive and moves a tape between one reel driven by one motor to another reel driven by another motor. The tape is read by a recording head composed of data readers, data writers and a dedicated set of servo read elements. A position and a velocity of the tape are determined from a primary velocity source when the tape is being read by the head. The position and the velocity of the tape are determined from a secondary velocity source when the tape is not being read by the head. The velocity of the tape is compared to a desired programmed reference velocity for the tape.
    Type: Grant
    Filed: October 28, 1999
    Date of Patent: June 22, 2004
    Assignee: International Business Machines Corporation
    Inventor: John Alexander Koski
  • Patent number: 6525913
    Abstract: First and second portions of a first shield layer on each side of a planar shield portion below a read sensor are recessed for receiving first and second insulative prefill layers which minimize electrical shorting between first and second hard bias layers and first and second lead layers to the first shield layer. The first and second prefill layers are close to first and second side edges of the read sensor so as to minimize shorting between the layers. By varying the depth of the first and second recesses in the first shield layer the first read gap layer or the second read gap layer can be planarized or, alternatively, each of the first and second read gap layers can be partially planarized, as desired.
    Type: Grant
    Filed: August 9, 2000
    Date of Patent: February 25, 2003
    Assignee: International Business Machines Corporation
    Inventors: Daniele Mauri, Hugo Alberto Emilio Santini
  • Patent number: 6496311
    Abstract: A method and system suitable for recording/reproducing audio-visual data on or from a hard disk or other storage media that can be accessed in random. Two streams, stream #1 and stream #2, are set. Then, 2000 sectors are set to the stream #1 and a specified number of sectors to the stream #2. By specifying this stream number (stream #1 or #2) and the audio-visual (AV) logical block address of the stream, the AV stream data recorded on the hard disk can be accessed. Each AV stream begins with zero and ends at the maximum AV stream LBA.
    Type: Grant
    Filed: October 12, 2000
    Date of Patent: December 17, 2002
    Assignee: International Business Machines Corporation
    Inventors: Masahiko Sato, Hideo Asano
  • Patent number: 6429704
    Abstract: A power consumption reduction circuit includes a clock frequency downconverting circuit. The clock frequency downconverting circuit downconverts a frequency of a CK signal, which is inputted, when a POR signal inputted is asserted, and outputs the CK signal to an IC selection circuit. In addition, if the POR signal inputted is negated, the clock frequency downconverting circuit outputs the CK signal inputted as it is to the IC selection circuit. A signal outputted from the clock frequency downconverting circuit is supplied to a plurality of ICs through the IC selection circuit.
    Type: Grant
    Filed: September 28, 2000
    Date of Patent: August 6, 2002
    Assignee: International Business Machines Corporation
    Inventors: Toshio Kanai, Masayuki Murakami, Yasuhiro Takase
  • Patent number: 6275028
    Abstract: In accordance with the present invention, the initialization for orienting the magnetized directions of the free layers of GMR heads (mounted on the diagonally shaded surface of sliders 14) by an external magnetic field is again executed also for the opposite direction, thereby to increase the yield of the GMR heads. Further, it is determined whether the magnetized direction of the pinned layer of GMR heads can be once reversed to the opposite direction, thereby to select damaged GMR heads at an early stage. Then, by performing a reset while performing a quasi-static test for seeing the read back response of the GMR head after restoring the magnetized direction of the pinned layer to a positive rotation, a safe and efficient reset is executed. The reset can be executed not only by applying only a pulse, but also while providing an external magnetic field in the pinning direction, or only by giving a high magnetic field.
    Type: Grant
    Filed: December 23, 1998
    Date of Patent: August 14, 2001
    Assignee: International Business Machines Corporation
    Inventors: Takao Matsui, Tatsuya Endo, Hiroaki Suzuki, Kenji Kuroki, Katsushi Yamaguchi, Hideo Asano
  • Patent number: 6238531
    Abstract: An ion beam sputtering system having a chamber, an ion beam source, multiple targets, a shutter, and a substrate stage for securely holding a wafer substrate during the ion beam sputtered deposition process in the chamber. The substrate stage is made to tilt about its vertical axis such that the flux from the targets hit the wafer substrate at a non-normal angle resulting in improved physical, electrical and magnetic properties as well as the thickness uniformity of the thin films deposited on the substrate in the ion beam sputtering system.
    Type: Grant
    Filed: July 10, 2000
    Date of Patent: May 29, 2001
    Assignee: International Business Machines Corporation
    Inventor: Mustafa Pinarbasi
  • Patent number: 6188550
    Abstract: A magnetic structure, such as a magnetoresistive sensor, having a continuous multi-region magnetic layer in which the magnetic and electrical characteristics of each region is locally defined. In the preferred embodiment, the continuous multi-region magnetic layer has high coercivity end regions separated by a low coercivity central region.
    Type: Grant
    Filed: December 5, 1996
    Date of Patent: February 13, 2001
    Assignee: International Business Machines Corporation
    Inventors: Robert Edward Fontana, Jr., Frances Anne Houle, Ching Hwa Tsang
  • Patent number: 6157962
    Abstract: A data processing system having multiple independent paths for communication between a host and a plurality of storage devices where each path has its own queue for servicing requests generated by the host for accessing the storage devices. Each request is assigned a unique sequential ID before it is stored, along with its unique ID, in all the queues. Each storage device has a "mailbox" register where the ID and the status of the latest request being carried out is stored. Queues are serviced and their status updated based on the content of the mailbox in each storage device. The combination of assigning a unique task ID to each request and a "mailbox" register in each storage device allows the queue in each path to be completely out of sync with each of the queues in the other paths without causing data integrity problems, duplication of requests at the device level, or a need for complex locking schemes to keep the queues in sync with each other.
    Type: Grant
    Filed: April 21, 1998
    Date of Patent: December 5, 2000
    Assignee: International Business Machines Corporation
    Inventors: Paul Hodges, Michael Garwood Hurley, Norman Kenneth Ouchi, Mien Shih
  • Patent number: 6117569
    Abstract: An SV sensor having a reference (pinned) layer formed of a first high uniaxial anisotropy ferromagnetic material, such as Co--Fe, and a keeper layer formed of a second high uniaxial anisotropy ferromagnetic material, such as Ni--Fe--Nb. Lapping induced stress in the high positive magnetostriction Co--Fe layer generates a uniaxial anisotropy field in the pinned layer resulting in enhanced pinned layer magnetization. This uniaxial anisotropy field adds to the exchange field from an antiferromagnetic layer resulting in a substantially increased pinning field over the pinning field from the exhange interaction alone. The added uniaxial anisotropy field also improves the stability of the SV sensor at elevated temperatures since the uniaxial field is determined by a Curie temperature significantly higher than the blocking temperatures of antiferromagnetic materials.
    Type: Grant
    Filed: May 27, 1998
    Date of Patent: September 12, 2000
    Assignee: International Business Machines Corporation
    Inventors: Tsann Lin, Daniele Mauri
  • Patent number: 6075667
    Abstract: A method and apparatus for positioning a head over a track in an information recording medium to eliminate head positioning error. Data tracks are concentrically formed on a magnetic disk, and identification information for identifying each data track is recorded so as to correspond to each data track. The identification information consists of first and second gray codes, and the first gray code is of n-1 bits where n represents the number of bits of a track address and set for each block so that it has a value different among a plurality of blocks each consisting of a plurality of data tracks. The second gray code is of three bits, and set for each data track so that it represents a value which differs between data tracks contiguous in the radial direction of the disk and circulates for every three or more blocks continuous in the radial direction of the disk. Head positioning is determined based on reading the first and second gray codes by the head.
    Type: Grant
    Filed: April 24, 1997
    Date of Patent: June 13, 2000
    Assignee: International Business Machines Corporation
    Inventors: Masashi Kisaka, Yoshiro Amano
  • Patent number: 6054330
    Abstract: In a magnetic read/write assembly, a removable fusible-link shorts the magnetoresistive (MR) sensor element to minimize electrical current through the MR sensing element during discharge of static electricity. Other magnetic head assembly elements such as the write coil and MR magnetic shields are also shorted using fusible-links. The fusible-link is removable during the assembly process. The existing terminal pads and wires are used to remove the fusible-link.
    Type: Grant
    Filed: December 4, 1997
    Date of Patent: April 25, 2000
    Assignee: International Business Machines Corporation
    Inventors: Peter Beverley Phipps, Erhard Theodor Schreck, Albert John Wallash
  • Patent number: 6055136
    Abstract: A magnetoresistive (MR) sensor comprises a dual differential spin valve structure. Each of the spin valves comprise first (free) and second (pinned) layers of ferromagnetic material separated by a thin film layer of nonmagnetic material. The magnetization direction of the pinned layers of ferromagnetic material in each spin valve is fixed, and their magnetization is set antiparallel to each other. A current flow is produced through the MR sensor, and the variations in voltage across the MR sensor are sensed due to changes in resistance of the MR sensor produced by rotation of the magnetization in the free layers of ferromagnetic material as a function of the magnetic field being sensed.
    Type: Grant
    Filed: July 22, 1997
    Date of Patent: April 25, 2000
    Assignee: International Business Machines Corporation
    Inventors: Hardayal Singh Gill, Bruce A. Gurney
  • Patent number: 6052263
    Abstract: A magnetic tunnel junction (MTJ) device is usable as a magnetic field sensor in magnetic disk drives or as a memory cell in a magnetic random access (MRAM) array. The MTJ device has a ferromagnetic antiparallel (AP)-pinned layer comprising a first ferromagnetic layer, a second ferromagnetic layer and an antiparallel coupling (APC) layer disposed between the first and second ferromagnetic layers, a free ferromagnetic layer and an insulating tunnel barrier layer disposed between the first ferromagnetic layer of the AP-pinned layer and the free ferromagnetic layer. The magnetization of the AP-pinned layer is oriented in the plane of the layer but is fixed so as not to be able to rotate in the presence of an applied magnetic field in the range of interest. The magnetization of the free ferromagnetic layer is able to be rotated in the plane of the layer relative to the fixed magnetization of the ferromagnetic AP-pinned layer.
    Type: Grant
    Filed: August 21, 1998
    Date of Patent: April 18, 2000
    Assignee: International Business Machines Corporation
    Inventor: Hardayal Singh Gill
  • Patent number: 6038107
    Abstract: An AP-Pinned SV sensor with the preferred structure of NiO/Ni--Fe/Co/Ru/Co/Cu/Ni--Fe/Cap where the pinned layer comprises first and second ferromagnetic pinned layers separated from each other by an anti-parallel coupling layer. The first ferromagnetic pinned layer further comprises a first pinned sub-layer of Ni--Fe and a second pinned sub-layer of Co where the first pinned sub-layer of Ni--Fe is formed over and in direct contact with the NiO antiferromagnetic (AFM) layer. Addition of the first pinned sub-layer of Ni--Fe isolates the second pinned sub-layer of Co from the NiO AFM layer resulting in dramatic improvement in the pinning field and magnetic moment control of the laminated AP-pinned layer.
    Type: Grant
    Filed: October 27, 1997
    Date of Patent: March 14, 2000
    Assignee: International Business Machines Corporation
    Inventor: Mustafa Pinarbasi
  • Patent number: 6033491
    Abstract: A spin valve (SV) sensor having a Ni-Mn antiferromagnetic (AFM) layer, a pinned layer, a free layer and a spacer layer disposed between said free and pinned layers. The pinned layer is formed over and in contact with the antiferromagnetic (AFM) Ni-Mn layer where the combination of the AFM and pinned layers is first annealed before depositing the rest of the SV layers. Carrying out the annealing process of the combination of the AFM and pinned layers prior to deposition of the rest of the SV layers provides the exchange coupling field necessary to pin the pinned layer while avoiding thermal degradation of the SV sensor giant magnetoresistive effect.
    Type: Grant
    Filed: September 3, 1997
    Date of Patent: March 7, 2000
    Assignee: International Business Machines Corporation
    Inventor: Tsann Lin
  • Patent number: 6016241
    Abstract: A heterogeneous thin film structure including a discontinuous layer of ferromagnetic material deposited on an insulating substrate and overcoated with a layer of nonmagnetic electrically conductive material exhibits giant magnetoresistance in saturation fields on the order of 350 Oersteds. A layer of ferromagnetic material is deposited on a heated insulating substrate by high vacuum evaporation techniques to form a layer of isolated ferromagnetic particles and overcoated with a nonmagnetic conductive material to form a plurality of ferromagnetic particles embedded in a nonmagnetic conductive matrix. As the ferromagnetic and nonmagnetic materials are deposited separately, it is not required that the two materials be immiscible and subsequent annealing is not required to induce phase separation.
    Type: Grant
    Filed: May 22, 1995
    Date of Patent: January 18, 2000
    Assignee: International Business Machines Corporation
    Inventors: Kevin Robert Coffey, James Kent Howard, Todd Lanier Hylton, Michael Andrew Parker
  • Patent number: 5993566
    Abstract: A spin valve (SV) sensor having a Ni--Mn antiferromagnetic (AFM) layer, a pinned layer, a free layer and a spacer layer disposed between said free and pinned layers. The pinned layer is formed over and in contact with the antiferromagnetic (AFM) Ni--Mn layer where the combination of the AFM and pinned layers is first annealed before depositing the rest of the SV layers. Carrying out the annealing process of the combination of the AFM and pinned layers prior to deposition of the rest of the SV layers provides the exchange coupling field necessary to pin the pinned layer while avoiding thermal degradation of the SV sensor giant magnetoresistive effect.
    Type: Grant
    Filed: October 10, 1997
    Date of Patent: November 30, 1999
    Assignee: International Business Machines Corporation
    Inventor: Tsann Lin
  • Patent number: 5937205
    Abstract: In a data processing system having a plurality of queues for prioritizing I/O requests to a storage device, the priority of the queues for servicing is dynamically adjustable as opposed to each queue having a fixed priority. Dynamically adjusting the priority of a queue allows the priority of a queue with "stuck" requests to be raised so the "stuck" requests can be serviced very quickly.
    Type: Grant
    Filed: December 6, 1995
    Date of Patent: August 10, 1999
    Assignee: International Business Machines Corporation
    Inventors: Richard Lewis Mattson, Jaishankar Moothedath Menon
  • Patent number: 5935453
    Abstract: A magnetoresistive (MR) sensor having passive end regions separated by a central active region in which an MR sensing element is formed over substantially only the central active region. The MR sensor is defined by forming a resist pattern over both the end regions and the MR sensing element followed by an etching step where the duration of the etching is controlled by the time it takes to remove the exposed end regions' material and not by the time it takes to remove the excess MR material in the center active region. This creates an MR sensor having planar sides along the circumference of the end regions where the planar sides have no thinned edges or shoulders. The MR sensor further has no remnant MR material along the inner planar side of the end regions behind the MR sensor's trackwidth edge and adjacent to the MR sensor's back side.
    Type: Grant
    Filed: July 15, 1997
    Date of Patent: August 10, 1999
    Assignee: International Business Machines Corporation
    Inventors: Robert E. Fontana, Tsann Lin, Neil Leslie Robertson, Ching Hwa Tsang