Magnetic Information Storage Element Testing Patents (Class 324/210)
  • Patent number: 11592495
    Abstract: Disclosed is a test system including a transmitter, a receiver, a measuring circuit, and a control circuit. The transmitter is coupled to the receiver in a DC coupling manner, and includes: a signal input circuit determining an output signal according to an input signal; a current source coupled between the signal input circuit and a low power-supply terminal and configured to determine a total current passing through the signal input circuit in a non-open/short-circuited condition; and a signal output wire circuit outputting the output signal for a performance test. The receiver includes: an impedance circuit coupled to the signal output wire circuit; and a coupling circuit coupling the impedance circuit with a high power-supply terminal. The measuring circuit measures a target current/voltage between the high power-supply terminal and low power-supply terminal to generate a measurement result.
    Type: Grant
    Filed: October 12, 2020
    Date of Patent: February 28, 2023
    Assignee: REALTEK SEMICONDUCTOR CORPORATION
    Inventors: Fei Xu, Wei-Xiong He, Feng-Cheng Chang
  • Patent number: 11513169
    Abstract: Disclosed is a magnetometer architecture that couples one or more coils to a magnetic yoke to allow the reset of the magnetic yoke and one or more magnetic field sensors simultaneously after, for example, exposure to a large stray magnetic field. Also, disclosed is a magnetometer architecture that integrates separate magnetic pole pieces offset from the yoke that are each wound by a reset coil to allow reset of the one or more magnetic field sensors.
    Type: Grant
    Filed: April 5, 2019
    Date of Patent: November 29, 2022
    Assignee: Apple Inc.
    Inventors: Savas Gider, Chaitanya Mudivarthi, Joyce M. Mullenix
  • Patent number: 11320367
    Abstract: A testing system includes a production-type laser having optical modes of a production laser that interfaces with an optical path of a heat-assisted magnetic recording (HAMR) slider. A far-field light illumination path delivers excitation light from the production-type laser to the optical path of the HAMR slider, the excitation light being emitted from an air bearing surface (ABS) of the HAMR slider. Optics receive the emitted light from the ABS and distribute the emitted light to one or more sensors. The system determines, based on signals received from the one or more sensors, a depolarization of the emitted light and a coupling efficiency of the HAMR slider. The system may also measure light reflecting out of the optical path and Fourier transform these measurements to determine locations of reflections within the optical path.
    Type: Grant
    Filed: October 9, 2020
    Date of Patent: May 3, 2022
    Assignee: Seagate Technology LLC
    Inventors: Raghu Ambekar Ramachandra Rao, Aaron Edward Patz, Tae-Woo Lee
  • Patent number: 11062729
    Abstract: Embodiments of the present invention provide methods, systems, and computer program products for identifying damaged tunneling magnetoresistance (TMR) sensors. In one embodiment, resistances of a TMR sensor are measured upon application of one or both of negative polarity bias current and positive polarity bias current at a plurality of current magnitudes. Resistances of the TMR sensor can then be analyzed with respect to current, voltage, voltage squared, and/or power, including analyses of changes to slopes calculated with these values and hysteresis-induced fluctuations, all of which can be used to detect damage to the TMR sensor. The present invention also describes methods to utilize the measured values of neighbor TMR sensors to distinguish normal versus damaged parts for head elements containing multiple TMR read elements.
    Type: Grant
    Filed: April 8, 2019
    Date of Patent: July 13, 2021
    Assignee: International Business Machines Corporation
    Inventors: Milad Aria, Icko E. T. Iben, Guillermo F. Paniagua
  • Patent number: 11017828
    Abstract: An apparatus for generating a magnetic field including permanent magnets arranged in a plane, each magnet being spatially separated along the plane from the adjacent magnet by a predetermined spacing, each magnet having a magnetic polarity opposed to the polarity of the adjacent magnet such that a magnetic field of adjacent magnets is oriented substantially perpendicular to the plane and in opposite directions, each magnet being spatially separated in the plane from the adjacent magnet by a nonmagnetic material. A method for programming a magnetic device or sensor device using the apparatus is also described.
    Type: Grant
    Filed: June 25, 2018
    Date of Patent: May 25, 2021
    Assignee: CROCUS TECHNOLOGY SA
    Inventors: Jeremy Alvarez-Herault, Lucien Lombard, Quentin Stainer, Jeffrey Childress
  • Patent number: 10812120
    Abstract: Indication of an amount of processing performed in detection and removal of ingress noise may be provided. A frequency domain representation of a narrowband region of a digital input signal may be received. The received frequency domain representation of the narrowband region may be compared with a predetermined threshold. Results from the comparison of the received frequency domain representation of the narrowband region with the predetermined threshold may be aggregated. Based on the aggregated results, an indication of an amount of processing performed by an ingress exciser in removing the ingress noise may be provided.
    Type: Grant
    Filed: September 1, 2019
    Date of Patent: October 20, 2020
    Assignee: Cisco Technology, Inc.
    Inventors: Richard Meller, Glendon L. Akins, III, Denis Downey, James An, Koen Van Renterghem
  • Patent number: 10795807
    Abstract: An optimized test data selection strategy references a sampling file that identifies data attributes that serve as the basis of the test data selection strategy. By analyzing fields and the corresponding field values of the sample imprint, a total number of test data selected for inclusion into a sample dataset is reduced. The test data selection strategy provides an efficient methodology for implementing a data comparison testing process.
    Type: Grant
    Filed: February 12, 2019
    Date of Patent: October 6, 2020
    Assignee: Accenture Global Solutions Limited
    Inventors: Ajay Mody, Vikram Jugal Godani, Brad A. Gonnerman, Matthew Ngai, Vignesh Kasturi Ravichandran, Frederick S. Siy
  • Patent number: 10432921
    Abstract: In one embodiment, a digital zoom and panning system for digital video is disclosed including an image acquisition device to capture digital video images; an image buffer to store one or more frames of digital video images as source pixels; a display device having first pixels to display images; a user interface to accept user input including a source rectangle to select source pixels within frames of the digital video images, a destination rectangle to select target pixels within the display device to display images, and a region of interest within the digital video images to display in the destination rectangle; and a digital mapping and filtering device to selectively map and filter source pixels in the region of interest from the image buffer into target pixels of the display device in response to the user input.
    Type: Grant
    Filed: July 12, 2018
    Date of Patent: October 1, 2019
    Assignee: Intuitive Surgical Operations, Inc.
    Inventors: Brian D. Hoffman, Christopher J. Hasser, William C. Nowlin
  • Patent number: 10198047
    Abstract: An information handling system includes an electrical connector to mate with terminals of a data storage device. The system further includes a temperature sensor integrated at the electrical connector. The temperature sensor is arranged to thermally couple to an exterior surface of the data storage device when the data storage device is fully inserted into the electrical connector.
    Type: Grant
    Filed: November 19, 2015
    Date of Patent: February 5, 2019
    Assignee: Dell Products, LP
    Inventors: Robert B. Curtis, Chris E. Peterson, Bernard D. Strmiska
  • Patent number: 10172237
    Abstract: A space-efficient Printed Circuit Board (PCB)-based inductor includes a first set of inductor turns formed on the printed circuit board and arranged to form a first toroidal end section, a second set of inductor turns formed on the printed circuit board and arranged to form a first cylindrical side section, a third set of inductor turns formed on the printed circuit board and arranged to form a second toroidal end section, and a fourth set of inductor turns formed on the printed circuit board and arranged to form a second cylindrical side section. The first toroidal end section, first cylindrical side section, second toroidal end section, and second cylindrical side section are connected in series.
    Type: Grant
    Filed: August 28, 2017
    Date of Patent: January 1, 2019
    Assignee: OSRAM SYLVANIA Inc.
    Inventors: Alireza Safaee, Thomas Dreeben, John Cross
  • Patent number: 10119936
    Abstract: An electromagnetic field analysis method for an anisotropic conductive material involves using an analysis grid having a first side and a second side that are orthogonal to each other to analyze an electromagnetic property of an anisotropic conductive material in which conductivity in a first direction is different from conductivity in a second direction. One or both of the first direction and the second direction are parallel to a direction different from either one of the first side and the second side of the analysis grid. One electromagnetic field component located on the first side and extending along the second side is calculated based on electromagnetic field components that are located on a plurality of the second sides surrounding the one electromagnetic field component and that extend along the second sides.
    Type: Grant
    Filed: January 26, 2017
    Date of Patent: November 6, 2018
    Assignee: SUBARU CORPORATION
    Inventor: Hiroyuki Tsubata
  • Patent number: 10029423
    Abstract: A printing correction method and a 3D printing device are provided, and the printing correction method is adapted to the 3D printing device having a printing platform. The printing correction method is as follows. An electric field is provided to the printing platform. A detection probe is extended towards a position of the printing platform along a first axial direction to enter the electric field, where the position is defined as an initial position. The detection probe is moved from the initial position along a moving path on the printing platform, and when the detection probe is moved along the moving path, an electric field variation is detected to determine a tilt variation of the printing platform relative to the first axial direction. It is determined whether to correct the printing platform according to the tilt variation of the printing platform.
    Type: Grant
    Filed: December 31, 2015
    Date of Patent: July 24, 2018
    Assignees: XYZprinting, Inc., Kinpo Electronics, Inc., Cal-Comp Electronics & Communications Company Limited
    Inventors: Chih-Ming Chang, Tzu-Yu Chen
  • Patent number: 9928873
    Abstract: An apparatus comprises a slider configured for writing data to and reading data from a magnetic recording medium and for heat-assisted magnetic recording. The slider comprises a heater configured to receive an AC signal and to cause oscillation in a spacing between the slider and the medium, and a contact sensor situated on the slider and configured to produce a DC response signal. A detector is coupled to the slider and configured to measure an amplitude of a spike in the DC response signal, calculate a ratio between the spike amplitude and an amplitude of the DC response signal, and detect contact between the slider and the medium in response to the ratio exceeding a predetermined threshold.
    Type: Grant
    Filed: June 30, 2017
    Date of Patent: March 27, 2018
    Assignee: SEAGATE TECHNOLOGY LLC
    Inventors: Dongming Liu, Huazhou Lou, Eric John McCalla, James Robert Oscarson, Shawn S. Silewski
  • Patent number: 9911482
    Abstract: A non-volatile memory system includes a first circuit and a second circuit both coupled to a magnetoresistance tunnel junction (MTJ) cell to substantially reduce the level of current flowing through the MTJ with rise in temperature, as experienced by the MTJ. The first circuit is operable to adjust a slope of a curve representing current as a function of temperature and the second circuit is operable to adjust a value of the current level through the MTJ to maintain current constant or to reduce current when the temperature increases. This way sufficient current is provided for the MTJ at different temperatures to prevent write failure, over programming, MTJ damage and waste of current.
    Type: Grant
    Filed: February 16, 2017
    Date of Patent: March 6, 2018
    Assignee: Avalanche Technology, Inc.
    Inventors: Ebrahim Abedifard, Parviz Keshtbod
  • Patent number: 9903909
    Abstract: An electronic device including electronics arranged in an electronics compartment and having electronic and/or electromechanical components. The device automatically detects and/or monitors wear of its electronic and/or electromechanical components and includes an apparatus for detecting and/or monitoring wear of the electronic and/or electromechanical components. Included is at least one element arranged in the electronics compartment. This element is independent of the electronics and has at least one physical property, which changes irreversibly as a function of wear of the element. The apparatus further includes a circuit for measuring the physical property, and an evaluating unit, which, based on the measured physical property, detects and/or monitors wear of the element and makes available a wear-dependent output signal.
    Type: Grant
    Filed: October 15, 2007
    Date of Patent: February 27, 2018
    Assignee: ENDRESS + HAUSER GMBH + CO. KG
    Inventors: Dietmar Spanke, Herbert Schroth, Manfred Hammer
  • Patent number: 9875764
    Abstract: A slider is configured for heat-assisted magnetic recording to a magnetic recording medium. A low- or non-modulation interface is defined between the slider and the medium. A contaminant is present on the slider and between the slider and the medium. A controller is configured to control the slider to dislodge the contaminant from the slider by performing modulation-based contact detection at a location of the medium where modulation-based contact detection can accurately detect head-medium contact. The controller is also configured to perform friction-based contact detection using the slider devoid of the contaminant.
    Type: Grant
    Filed: February 14, 2017
    Date of Patent: January 23, 2018
    Assignee: SEAGATE TECHNOLOGY LLC
    Inventor: Jason W. Riddering
  • Patent number: 9865301
    Abstract: A method of forming a recording head for use with a data storage medium in a data storage device. The method includes forming first and second writers of different target geometries. A first recording measurement is performed on one or more storage media using the first writer. A second recording measurement is performed on the one or more storage media using the second writer. Based on a comparison of the first and second recording measurements to a predetermined quantity, either the first writer or the second writer is selected to be operational in the data storage device.
    Type: Grant
    Filed: January 15, 2016
    Date of Patent: January 9, 2018
    Assignee: Seagate Technology LLC
    Inventors: Kurt Wiesen, Javier Guzman, Joseph Mundenar, Michael Conover
  • Patent number: 9819475
    Abstract: A nanoionic switch connected to one or more rectenna modules is disclosed. The rectenna module is configured to receive a wireless signal and apply a first bias to change a state of the nanoionic switch from a first state to a second state. The rectenna module can receive a second wireless signal and apply a second bias to change the nanoionic switch from the second state back to the first state. The first bias is generally opposite of the first bias. The rectenna module accordingly permits operation of the nanoionic switch without onboard power.
    Type: Grant
    Filed: October 14, 2016
    Date of Patent: November 14, 2017
    Assignee: The United States of America as Represented by the Administrator of National Aeronautics and Space Administration
    Inventors: James A. Nessel, Felix A Miranda
  • Patent number: 9753930
    Abstract: A method for writing a file from an application of a host onto a tape includes sequentially receiving records forming the file from the application, adding a predetermined number of segments of dummy data (dummy records) subsequently to the plurality of records forming the file such that the records of the file and records of a subsequent file are not included in the same data set, interposing the dummy records between a final record of the file and a head record of the subsequent (next) file, to thereby construct at least one data set that is adjacent to one data set and does not include the records of the file, and writing a data set including the records of the file, a data set (dummy data set) including the final record of the file and the dummy records, and a data set including the subsequent file, onto the tape.
    Type: Grant
    Filed: October 26, 2015
    Date of Patent: September 5, 2017
    Assignee: International Business Machines Corporation
    Inventors: Masayuki Iwanaga, Yumiko Ohta, Yutaka Oishi
  • Patent number: 9704519
    Abstract: For each head in a collection of heat-assisted magnetic recording read/write heads, a reader width and a writer width is measured. A predicted life is determined for each head based on the respective reader width and writer width. In a first set of drives having relatively fewer heads per drive, a first subset of the heads having a higher value of the predicted life are used. In a second set of drives having relatively more heads per drive, a second subset of the heads having a lower value of the predicted life are used.
    Type: Grant
    Filed: February 10, 2016
    Date of Patent: July 11, 2017
    Assignee: SEAGATE TECHNOLOGY LLC
    Inventors: Wenzhong Zhu, Edward Charles Gage, Alfredo Sam Chu
  • Patent number: 9568523
    Abstract: A measurement bridge circuit includes a first branch and a second branch. The first branch contains a first resistor which is sensitive to measured variables and an invariable resistor connected in series. A first tap point is located between the first resistor and the invariable resistor. The second branch contains a second resistor which is sensitive to measured variables and a variable resistor arrangement connected in series. The variable resistor arrangement includes a first component having an invariable electrical resistance value and a second component having a variable electrical resistance value. The second component is connected in parallel with the first component in order to vary a total electrical resistance value for the variable resistor arrangement. A second tap point is located between the second resistor and the variable resistor arrangement.
    Type: Grant
    Filed: September 6, 2012
    Date of Patent: February 14, 2017
    Assignee: Robert Bosch GmbH
    Inventors: Ingo Herrmann, Roland Mueller-Fiedler, Veronique Krueger
  • Patent number: 9548083
    Abstract: A read head is tested by measuring the thermal magnetic fluctuation noise spectrum. A non-uniformity in the magnetic field of the free layer is produced and the thermal magnetic fluctuation noise spectrum is measured, with and/or without an external magnetic field applied. A peak in the thermal magnetic fluctuation noise spectrum can be used to derive the desired dimension of the free layer, such as track width and stripe height. The resulting measurement may then be fed back into the process control for the production of the read heads if desired. Additionally, the stiffness of the free layer and the strength of the reference layer may be determined using ferromagnetic resonance peaks in the thermal magnetic fluctuation noise spectrum.
    Type: Grant
    Filed: December 10, 2007
    Date of Patent: January 17, 2017
    Assignee: Infinitum Solutions, Inc.
    Inventors: Alexander M. Taratorin, Henry Patland, Wade A. Ogle
  • Patent number: 9491118
    Abstract: A nanoionic switch connected to one or more rectenna modules is disclosed. The rectenna module is configured to receive a wireless signal and apply a first bias to change a state of the nanoionic switch from a first state to a second state. The rectenna module can receive a second wireless signal and apply a second bias to change the nanoionic switch from the second state back to the first state. The first bias is generally opposite of the first bias. The rectenna module accordingly permits operation of the nanoionic switch without onboard power.
    Type: Grant
    Filed: October 5, 2012
    Date of Patent: November 8, 2016
    Assignee: The United States of America as Represented by the Administrator of National Aeronautics and Space Administration
    Inventors: James A. Nessel, Felix A Miranda
  • Patent number: 9476926
    Abstract: In one embodiment, a method for determining electrostatic discharge (ESD) includes building a slider delta comparison map using slider electrical and/or row bar quasi testing results, wherein row bar quasi testing is performed on row bars of multiple sliders, and wherein slider electrical testing is performed on individual sliders, determining whether a test device in a parent job passes primary ESD delta criteria, when the test device fails the primary ESD delta criteria: flagging the parent job of the test device as a reroute job and performing automatic actual parts rerouting for any jobs related to the parent job to pull parts from a test bin as opposed to a supply bin, wherein all parts pulled from the test bin are tested prior to assembly as opposed to parts pulled from the supply bin which are not 100% tested.
    Type: Grant
    Filed: June 11, 2013
    Date of Patent: October 25, 2016
    Assignee: HGST Netherlands B.V.
    Inventors: Ciaran A. Fox, Ma. V. C. Maceren, Ray N. M. Tag-at
  • Patent number: 9453868
    Abstract: When static electrical charge by electromagnetic waves is applied to a test-target board or test noises are applied to the ground of the test-target board, a test device tests as to whether or not noises are conducted through a path from an OUT terminal of an amplifier circuit to the ground of the test-target board, and a test device tests as to whether or not noises are conducted through a path from an OUT terminal of an amplifier circuit to the ground of the test-target board together with the number of conductions.
    Type: Grant
    Filed: March 23, 2012
    Date of Patent: September 27, 2016
    Assignee: MITSUBISHI ELECTRIC CORPORATION
    Inventors: Hiroyuki Kimata, Satoru Ishizaka
  • Patent number: 9349415
    Abstract: A signal is recorded over at least part of a track a heat-assisted recording medium via a heat-assisted magnetic recording head. Symmetry of a cross-track profile of the recorded signal is determined, and the recording head is qualified based on the symmetry of the cross-track profile.
    Type: Grant
    Filed: May 19, 2015
    Date of Patent: May 24, 2016
    Assignee: SEAGATE TECHNOLOGY LLC
    Inventors: Drew Michael Mader, Alfredo Sam Chu, Tim Rausch
  • Patent number: 9317050
    Abstract: A method and apparatus for controlling a converter of a fuel cell vehicle that uses a power control value generated based on an inverter DC terminal voltage as a reference value, and generates a current reference signal based on the reference value is provided. More specifically, the method and apparatus output a final reference signal that generates a pulse width modulation (PWM) signal by compensating for the current reference signal based on output terminal current of the converter. A peak value is then increased by amplifying a triangular wave signal, and the amplified triangular wave signal and the compensated final reference signal according to the current reference signal change rate are compared. A PWM signal having a predetermined duty ratio is then generated to control the converter.
    Type: Grant
    Filed: December 3, 2013
    Date of Patent: April 19, 2016
    Assignees: Hyundai Motor Company, Kia Motors Corporation
    Inventors: Ji Tae Kim, Boung Ho Min, Jae-Moon Lee, Ho Sung Kang
  • Patent number: 9318031
    Abstract: The invention pertains to a head-disk assembly device, “mass spin-valve” or “gravitational rectifier” and method of producing gravitomagnetic induction utilizing Nano-features; Nano-bumps and Nano-pits; fabricated on the surface of a hard disk. The device includes a computer hard disk; a piezoelectric glide head and/or a GMR read head; a typical hard drive's electronics; wherein, defects are fabricated on the said disk using a Focused Ion Beam (FIB) by depositing requisite number of nanobumps of specified height, and etching equal number of nanopits of specified depth a few mils or mm apart on a pre-decided radius. By spinning the said nano-features disk produce (1) an associated mechanical force utilizing a piezoelectric glide head and/or (2) an associated magnetic force utilizing a GMR read head; for (a) general use in surface characterization work and (b) for producing power by the presence or the absence of matter on a spinning disk.
    Type: Grant
    Filed: August 27, 2012
    Date of Patent: April 19, 2016
    Inventor: Michael Edward Boyd
  • Patent number: 9251810
    Abstract: Methods and systems for detecting a damaged magnetoresistive sensor are disclosed. In one embodiment, resistances of a plurality of sensors are measured at at least a first bias current level. Further, it is determined whether one of the sensors has a resistance that is at least a predetermined amount higher or lower than the resistances of the other sensors. Moreover, output indicates that the one of the sensors has a resistance that is at least a predetermined amount higher than the resistances of the other sensors.
    Type: Grant
    Filed: December 20, 2011
    Date of Patent: February 2, 2016
    Assignee: International Business Machines Corporation
    Inventor: Icko E. Tim Iben
  • Patent number: 9093083
    Abstract: Technologies are described herein for adapting a read-signal in a read channel using pre-determined sets of adaptive parameter values optimized for different noise environments in a storage device. A read-signal is received in a read channel comprising at least one adaptive component. A most probable noise type is determined for the read channel, and a set of adaptive parameter values associated with the most probable noise type is retrieved from a memory. The read-signal is adapted for decoding using the at least one adaptive component configured with the retrieved set of adaptive parameter values.
    Type: Grant
    Filed: October 1, 2014
    Date of Patent: July 28, 2015
    Assignee: Seagate Technology LLC
    Inventors: Gukhui Kim, Seungyoul Jeong, Jiyoung Lee, Wonseo Park
  • Patent number: 9070405
    Abstract: An implementation of a system disclosed herein provides a method of determining a frequency of baseline noise in a target or read sensor signal and rejecting a band of signals from the target or read sensor signal substantially around the frequency of the baseline noise, including devices to implement this method.
    Type: Grant
    Filed: September 30, 2013
    Date of Patent: June 30, 2015
    Assignee: SEAGATE TECHNOLOGY LLC
    Inventors: JungWook Hur, TaeYoung Kim
  • Patent number: 9047521
    Abstract: A computer implemented method for diagnosing a magnetic reader subassembly. A processor generates a test signal during a diagnostic period. The processor then receives a return signal from the magnetic reader subassembly. The processor then compares the test signal and the return signal and diagnoses an operational status of the magnetic reader subassembly in response to the comparison of the test signal and the return signal.
    Type: Grant
    Filed: November 15, 2006
    Date of Patent: June 2, 2015
    Assignee: International Business Machines Corporation
    Inventors: Robert Thomas Cato, Phuc Ky Do, Justin Monroe Pierce
  • Patent number: 8934185
    Abstract: Technologies are described herein for recovering an instable head in a storage device using an internal head heater. An instability in the reader head may be detected, and, in response to detecting the instability, a thermal shock may be applied to the reader head utilizing the head heater to recover the head.
    Type: Grant
    Filed: December 21, 2012
    Date of Patent: January 13, 2015
    Assignee: Seagate Technology LLC
    Inventors: Jung Wook Hur, Won Choul Yang, Haejung Lee
  • Patent number: 8860407
    Abstract: A method and system for testing a read transducer are described. The read transducer includes a read sensor fabricated on a wafer. A system includes a test structure that resides on the wafer. The test structure includes a test device and a heater. The test device corresponds to the read sensor. The heater is in proximity to the test device and is configured to heat the test device substantially without heating the read sensor. Thus, the test structure allows for on-wafer testing of the test device at a plurality of temperatures above an ambient temperature.
    Type: Grant
    Filed: March 30, 2012
    Date of Patent: October 14, 2014
    Assignee: Western Digital (Fremont), LLC
    Inventors: Changhe Shang, Daniele Mauri, Kuok San Ho
  • Patent number: 8810241
    Abstract: A system and method for detecting a damaged magnetoresistive sensor includes measuring a median DiffPN value of a group of GMR sensors on a module, the sensors characterized as having been deposited on a same wafer and having been lapped as a single unit; comparing the DiffPN values to the median; determining that physical and/or magnetic damage has occurred to an individual sensor if the difference in the DiffPN value of the individual sensor from the median is greater than a statistically predetermined value for the group of sensors; where the difference is at least one times the average of the standard deviations of a large number of normal modules or the average of the standard deviations of a large number of modules, wherein at least the largest and the smallest DiffPN value within the module is not included in the calculation of the module's standard deviation.
    Type: Grant
    Filed: July 19, 2011
    Date of Patent: August 19, 2014
    Assignee: International Business Machines Corporation
    Inventors: Icko E. Tim Iben, Darrell G. Follett, Guillermo Paniagua
  • Patent number: 8749917
    Abstract: An adjustable disk stabilizer for a spinstand having a spindle motor and spindle assembly for supporting and rotating a magnetic medium bearing disk. The spinstand is adapted to position a transducing (read/write) head adjacent to the magnetic medium. The adjustable disk stabilizer is attached to a stationary portion of the spindle assembly, and includes a mechanism to adjust height and alignment of a plate having a bearing surface opposite a non-magnetic-media-bearing undersurface of the disk. That bearing surface, in concert with the undersurface of the disk, establishes a supporting air bearing therebetween during rotation of the media-bearing disk. The adjustment mechanism enables easily-attained compensation for various disk-to-disk thicknesses and level imperfections of the bearing surface plate mounting, and enables precision alignment of the bearing surface of the plate to the surface of the disk opposite to the surface under test.
    Type: Grant
    Filed: April 4, 2013
    Date of Patent: June 10, 2014
    Assignee: Guzik Technical Enterprises
    Inventors: Konstantin Perevoztchikov, Wei Zhuang, Nahum Guzik
  • Patent number: 8680855
    Abstract: A measuring circuit system in a magnetic field measuring apparatus of the invention has an amplifier and a band-pass filter connected in sequence on an output terminal side of the TMR element, the band-pass filter is a narrow-range band-pass filter such that a peak pass frequency of the filter that is a center is a basic frequency selected from a range of 10 to 40 GHz and a band width centered around the basic frequency is a narrow range of ±0.5 to ±4 GHz; and with the measuring circuit system, an S/N ratio (SNR) of 3 dB or greater is obtained, the SNR being defined by a ratio of an amplitude S of a high-frequency generated signal induced by the TMR element to a total noise N that is a sum of a head noise generated by the TMR element and a circuit noise generated by the amplifier. With such a configuration, an in-plane high-frequency magnetic field generated by a microwave-assisted magnetic head is reliably and precisely measured.
    Type: Grant
    Filed: December 26, 2012
    Date of Patent: March 25, 2014
    Assignee: TDK Corporation
    Inventors: Isamu Sato, Hiroshi Ikeda, Mikio Matsuzaki, Tetsuya Roppongi, Noboru Yamanaka, Tsutomu Aoyama
  • Patent number: 8683456
    Abstract: Systems and methods are provided for testing a non-volatile memory, such as a flash memory. The non-volatile memory may be virtually partitioned into a test region and a general purpose region. A test application may be stored in the general purpose region, and the test application can be executed to run a test of the memory locations in the test region. The results of the test may be stored in the general purpose region. At the completion of the test, the test results may be provided from the general purpose region and displayed to a user. The virtual partitions may be removed prior to shipping the electronic device for distribution.
    Type: Grant
    Filed: July 13, 2009
    Date of Patent: March 25, 2014
    Assignee: Apple Inc.
    Inventors: Matthew Byom, Nir J. Wakrat, Kenneth Herman
  • Patent number: 8664950
    Abstract: A method for measuring longitudinal bias magnetic field in a tunnel magnetoresistive sensor of a magnetic head, the method includes the steps of: applying an external longitudinal time-changing magnetic field onto the tunnel magnetoresistive sensor; determining a shield saturation value of the tunnel magnetoresistive sensor under the application of the external longitudinal time-changing magnetic field; applying an external transverse time-changing magnetic field and an external longitudinal DC magnetic field onto the tunnel magnetoresistive sensor; determining a plurality of different output amplitudes under the application of the external transverse time-changing magnetic field and the application of different field strength values of the external longitudinal DC magnetic field; plotting a graph according to the different output amplitudes and the different field strength values; and determining the strength of the longitudinal bias magnetic field according to the graph and the shield saturation value.
    Type: Grant
    Filed: July 1, 2011
    Date of Patent: March 4, 2014
    Assignee: SAE Magnetics (H.K.) Ltd.
    Inventors: Siuman Mok, Hokei Lam, Cheukwing Leung, Juren Ding, Rongkwang Ni, Wanyin Kwan, Cheukman Lui, Chiuming Lueng
  • Patent number: 8653824
    Abstract: A method for quasi-static testing a magnetic recording head read sensor is described. The method includes applying a first voltage to a heater in the magnetic recording head and measuring an output of the magnetic recording head read sensor while applying the first voltage to the heater and recording the measured output as a first set of measurements. The method further includes applying a second voltage to the heater in the magnetic recording head and measuring the output of the magnetic recording head read sensor while applying the second voltage to the heater and recording the measured output as a second set of measurements. The first and second sets of measurements are then compared.
    Type: Grant
    Filed: December 16, 2009
    Date of Patent: February 18, 2014
    Assignee: Western Digital (Fremont), LLC
    Inventors: Feng Liu, Mehran Zargari
  • Patent number: 8621658
    Abstract: A magnetic-field-observation device and method for measuring magnetic force near a magnetic material specimen's surface with high resolution and detecting the polarity of the magnetic pole of specimen's surface.
    Type: Grant
    Filed: September 5, 2011
    Date of Patent: December 31, 2013
    Assignee: Akita University
    Inventors: Hitoshi Saito, Satoru Yoshimura
  • Patent number: 8618793
    Abstract: A tool for testing a magnetic disk for use in a magnetic disk drive. The tool detects surface defects or asperities by detecting a change in electrical resistance corresponding to a temperature change in a thermally sensitive layer. The apparatus includes a slider body having a thermally insulating layer formed on an air bearing surface of the slider body and a thermal sensor layer formed on the thermally insulating layer. The thermally insulating layer prevents thermal heat spikes in the thermal sensor layer (such as resulting from contact with an asperity) from dissipating quickly into the slider body itself. The thermal sensor layer is a material that exhibits a change in electrical resistance in response to a change in temperature and is preferably a PTC thermistor material which exhibits a large change in electrical resistance when a transition temperature has been reached.
    Type: Grant
    Filed: December 23, 2009
    Date of Patent: December 31, 2013
    Assignee: HGST Netherlands B.V.
    Inventors: Shanlin Duan, Jizhong He, John S. Hopkins, Kenneth E. Johnson
  • Patent number: 8552716
    Abstract: In one embodiment, a manufacturing method for magnetic heads includes classifying magnetic heads into one of: a first tested head class, and a non-test-candidate head class, determining characteristic values of the magnetic heads classified in the first tested head class, estimating characteristic values of the magnetic heads classified in the non-test-candidate head class, wherein the estimating is based on the characteristic values of the magnetic heads classified in the first tested head class, classifying each of the magnetic heads classified in the non-test-candidate head class into one of: a second tested head class, and a non-test head class based on the estimated characteristic values, determining characteristic values of the magnetic heads classified in the second tested head class, and screening magnetic heads in the second tested head class based on the determined characteristic values of the magnetic heads classified in the second tested head class.
    Type: Grant
    Filed: December 8, 2010
    Date of Patent: October 8, 2013
    Assignee: HGST Netherlands B.V.
    Inventors: Fumiomi Ueda, Makoto Ono
  • Publication number: 20130257421
    Abstract: A method and system for testing a read transducer are described. The read transducer includes a read sensor fabricated on a wafer. A system includes a test structure that resides on the wafer. The test structure includes a test device and a heater. The test device corresponds to the read sensor. The heater is in proximity to the test device and is configured to heat the test device substantially without heating the read sensor. Thus, the test structure allows for on-wafer testing of the test device at a plurality of temperatures above an ambient temperature.
    Type: Application
    Filed: March 30, 2012
    Publication date: October 3, 2013
    Applicant: WESTERN DIGITAL (FREMONT), LLC
    Inventors: CHANGHE SHANG, DANIELE MAURI, KUOK SAN HO
  • Patent number: 8544164
    Abstract: According to one embodiment, a head stack assembly cartridge is provided. The head stack assembly cartridge includes a base plate having a pivot shaft for pivotally mounting a head stack assembly and a base voice coil motor magnet attached to an inner surface of the base plate. The base voice coil motor magnet is arranged on the inner surface of the base plate to be adjacent to a coil of the head stack assembly pivotally mounted on the pivot shaft. The head stack assembly cartridge further includes a cover removably attached to the base plate and a pivot clamp removably attached to the cover and configured to secure the head stack assembly pivotally mounted on the pivot shaft.
    Type: Grant
    Filed: August 21, 2012
    Date of Patent: October 1, 2013
    Assignee: Western Digital Technologies, Inc.
    Inventors: Chunjer Chuck Cheng, Tao Lin, Gang Herbert Lin
  • Patent number: 8516686
    Abstract: A slider tester includes a disk, movable table, table drive mechanism, guide member, etc. A plurality of suspensions are mounted on the movable table. A slider is mounted on each suspension. A guide member can support respective lift tabs of the suspensions. The guide member includes a first guide surface, second guide surface, and opening arranged in a track width direction of the disk. When any of the lift tabs gets into the opening as the movable table moves in the track width direction of the disk, the slider is dropped toward a recording surface of the disk.
    Type: Grant
    Filed: June 18, 2012
    Date of Patent: August 27, 2013
    Assignee: NHK Spring Co., Ltd.
    Inventor: Akira Nojima
  • Patent number: 8510931
    Abstract: A disc drive disc stack assembly and a method for forming the disc stack assembly to reduce servo pattern runout. The disc stack assembly includes a number of prewritten discs having a servo pattern and a disc alignment mark. The first step is to place a first disc about a spindle motor hub of the disc drive. The second step is to align a disc alignment mark of the first disc in relation to a direction of a biasing force. The third step is to apply the biasing force to the first disc to engage the first disc against the spindle motor hub. The fourth step is to repeat the first three steps for each remaining disc in the disc stack assembly. The final step is to clamp the prewritten discs with a disc clamp to secure the position of each prewritten disc relative to the spindle motor hub.
    Type: Grant
    Filed: October 17, 2001
    Date of Patent: August 20, 2013
    Assignee: Seagate Technology LLC
    Inventor: Arnold G. Slezak
  • Patent number: 8493683
    Abstract: Measuring method of a magnetic head includes (a) placing the magnetic head at normal position, defining a first direction parallel to an air bearing surface and two shielding layers of the magnetic head, and defining a second direction perpendicular to the first direction; (b) tilting the magnetic head at an angle to the second direction, applying a plurality of first magnetic fields with different intensities in the first direction, and measuring out a first output parameter curve; (c) repeating the step (b) with different angles and measuring out a plurality of first output parameter curves; (d) calculating a plurality of pinned direction tilt ratios that a pinned direction of a pinned layer of the magnetic head tilts towards the second direction according to the parameter curves; and (e) calculating a pinned direction tilt angle that the pinned direction tilts towards the second direction according to the pinned direction tilting ratios.
    Type: Grant
    Filed: November 4, 2011
    Date of Patent: July 23, 2013
    Assignee: SAE Magnetics (H.K.) Ltd.
    Inventors: Chiu ming Lueng, Mankit Lee, Cheukwing Leung, Ju ren Ding, Rong kwang Ni
  • Patent number: 8487609
    Abstract: A test apparatus can test a read head and/or a disk. The test apparatus includes a rotatable spindle adapted to hold the disk, and a holder oriented to hold the read head with its air bearing surface adjacent the major surface of the disk during testing. The holder includes a channel with a first side wall. The channel defines a channel longitudinal axis parallel to the first side wall. The channel also defines a lateral direction that is normal to the first side wall. A first gas jet points into the channel and impinges upon a top face of the read head.
    Type: Grant
    Filed: December 14, 2010
    Date of Patent: July 16, 2013
    Assignee: Microphysics, Inc.
    Inventor: Christopher Allen Lacey
  • Publication number: 20130154628
    Abstract: A method for judging a coercive force of a magnetic recording medium, so recording magnetic information can be formed in either a low coercivity magnetic medium or a high coercivity magnetic medium by using a magnetic head. A magnetic information recording step writes magnetic information in the magnetic recording medium by alternately using a first write current suitable for writing in the low coercivity magnetic medium and a second write current suitable for writing in the high coercivity magnetic medium. A magnetic information reproducing step reproduces the magnetic information written in the magnetic recording medium. A judging step makes a judgment on a coercive force of the magnetic recording medium by way of comparing a first reproduced output A of the magnetic information written with the first write current and a second reproduced output B of the magnetic information written with the second write current.
    Type: Application
    Filed: March 29, 2012
    Publication date: June 20, 2013
    Inventor: Hisashi Yamamoto