Patents by Inventor Zhong-heng Lin

Zhong-heng Lin has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 7215495
    Abstract: A system and method for determining head-disk contact (HDC) in a magnetic recording disk drive uses the signal from the magnetoresistive (MR) read head. The analog MR signal is digitized and input to a digital signal processor with circuitry and/or software for integrating the signal amplitude over a low-frequency range. The calculated value from the integration when the slider is out-of-contact with the disk is a reference value. The same integration is then performed during operation of the disk drive and the measured value is compared to the reference value. If the measured value exceeds the reference value by some predetermined amount, this is an indication of the onset of HDC or that HDC has occurred.
    Type: Grant
    Filed: December 27, 2005
    Date of Patent: May 8, 2007
    Assignee: Hitachi Global Storage Technologies Netherlands B.V.
    Inventors: Xiaodong Che, Weidong Huang, Terence Tin-Lok Lam, Zhong-heng Lin, Alex Shteyn
  • Patent number: 7180692
    Abstract: A system and method for calibrating and controlling a magnetic recording disk drive fly-height actuator uses the signal from the magnetoresistive (MR) read head to determine head-disk contact (HDC). The MR signal is measured over a low-frequency range, with the slider out-of-contact with the disk, to develop a reference value. The MR signal is then measured over the same low-frequency range and if it exceeds the reference value by some predetermined amount, this is an indication of HDC. The fly-height actuator control signal value for HDC is recorded and thus corresponds to a head-disk spacing of zero. The calibration method also determines the sensitivity of head-disk spacing to the fly-height actuator control signal by measuring a series of MR read signal amplitudes for a corresponding series of control signals.
    Type: Grant
    Filed: December 27, 2005
    Date of Patent: February 20, 2007
    Assignee: Hitachi Global Storage Technologies Netherlands B.V.
    Inventors: Xiaodong Che, Weidong Huang, Terence Tin-Lok Lam, Zhong-heng Lin, Alex Shteyn
  • Patent number: 7119537
    Abstract: A method for measuring a magnetic read width MRW of a magnetic read sensor directly from the derivative of a full track profile, with better accuracy and more advantages than the micro-track method was invented and also there is no need to use a separate wide write head. The magnetic write width MWW of the write head, without the influence of sensor side reading, can also be obtained by this method along with the MRW with no additional calculations.
    Type: Grant
    Filed: September 30, 2004
    Date of Patent: October 10, 2006
    Assignee: Hitachi Global Storage Technologies, Netherlands B.V.
    Inventors: Xiaodong Che, Terence Tin-Lok Lam, Zhong-heng Lin, Xiaoyu Sui
  • Publication number: 20060066300
    Abstract: A method for measuring a magnetic read width MRW of a magnetic read sensor directly from the derivative of a full track profile, with better accuracy and more advantages than the micro-track method was invented and also there is no need to use a separate wide write head. The magnetic write width MWW of the write head, without the influence of sensor side reading, can also be obtained by this method along with the MRW with no additional calculations.
    Type: Application
    Filed: September 30, 2004
    Publication date: March 30, 2006
    Inventors: Xiaodong Che, Terence Lam, Zhong-heng Lin, Xiaoyu Sui
  • Patent number: 6788481
    Abstract: A nonlinear transition shift (NLTS) measurement procedure for read/write heads employing a giant magnetoresistive (GMR) merged heads. The method of this invention includes the pulse-shape distortion effects on recording nonlinearity, which can significantly affect the existing theoretical formulae for calculating nonlinearity correction factor from measured partial erasure values, and second-order approximation of equation of NLTS and nonlinearity correction factor. Transition broadening effects (TBE) and partial erasure (PE) are incorporated in the NLTS measurement procedure to permit accurate isolation of the NLTS from the unrelated TBE/PE and GMR nonlinear transfer characteristic (NTC). First, a fifth harmonic elimination (5HE) test is performed at bit period T to measure a first nonlinearity value X.
    Type: Grant
    Filed: March 21, 2002
    Date of Patent: September 7, 2004
    Assignee: International Business Machines Corporation
    Inventors: Peter Chen-I Fang, Xiangjun Feng, Terence Tin-Lok Lam, Zhong-Heng Lin
  • Patent number: 6777929
    Abstract: A process, computer program product, and apparatus for detecting and quantifying crosstalk instability in a read/write mechanism are provided. A write current is varied in a write circuit for exciting the write head. Measurements are taken of a magnetoresistive impedance of a read current of a read circuit. Measurements are also taken of a signal amplitude in the read circuit. A bit error rate of the overall system is also measured. The read/write mechanism is failed if the signal amplitude changes by a predetermined amount during the varying of the write current. Likewise, the read/write mechanism is failed if the error rate changes by a predetermined amount during the varying of the write current. The write-to-read signal coupling of HGA (Head Gimbal Assembly) and HSA (Head Stack Assembly), including GMR sensor, suspension and flex cable on the actuator arm, can be evaluated at component design level. The methodologies successfully simulate GMR cross talk instability inside a drive on magnetic testers.
    Type: Grant
    Filed: August 27, 2002
    Date of Patent: August 17, 2004
    Assignee: International Business Machines Corporation
    Inventors: Peter Cheng-I Fang, Terence Tin-Lok Lam, Zhong-heng Lin
  • Publication number: 20040041559
    Abstract: A process, computer program product, and apparatus for detecting and quantifying crosstalk instability in a read/write mechanism are provided. A write current is varied in a write circuit for exciting the write head. Measurements are taken of a magnetoresistive impedance of a read current of a read circuit. Measurements are also taken of a signal amplitude in the read circuit. A bit error rate of the overall system is also measured. The read/write mechanism is failed if the signal amplitude changes by a predetermined amount during the varying of the write current. Likewise, the read/write mechanism is failed if the error rate changes by a predetermined amount during the varying of the write current. The write-to-read signal coupling of HGA (Head Gimbal Assembly) and HSA (Head Stack Assembly), including GMR sensor, suspension and flex cable on the actuator arm, can be evaluated at component design level. The methodologies successfully simulate GMR cross talk instability inside a drive on magnetic testers.
    Type: Application
    Filed: August 27, 2002
    Publication date: March 4, 2004
    Applicant: INTERNATIONAL BUSINESS MACHINES
    Inventors: Peter-Cheng -I Fang, Terence Tin-Lok Lam, Zhong-Heng Lin
  • Patent number: 6680609
    Abstract: A method of determining a magnetic track width of a magnetic head. The method begins by obtaining a full track profile of the magnetic head which includes a plurality of signal amplitudes read across a track of a magnetic disk at a plurality of magnetic head positions. An initial magnetic track width value is then determined from the full track profile data. Preferably, this initial value is the magnetic write width which is determined based on the difference between left and right head positions which read half of the maximum signal amplitude. To determine the final magnetic write width, the initial value is adjusted with side reading correction values. The side reading correction values are determined based on left and right side reading “tails” of a bell-shaped signal curve which is formed by the full track profile data when graphed. It is not necessary to obtain the microtrack profile to determine these side reading values.
    Type: Grant
    Filed: July 11, 2002
    Date of Patent: January 20, 2004
    Assignee: International Business Machines Corporation
    Inventors: Peter Cheng-I Fang, Terence Tin-Lok Lam, Zhong-heng Lin
  • Publication number: 20040010391
    Abstract: A method of determining a magnetic track width of a magnetic head is disclosed. The method begins by obtaining a full track profile of the magnetic head which includes a plurality of signal amplitudes read across a track of a magnetic disk at a plurality of magnetic head positions. An initial magnetic track width value is then determined from the full track profile data. Preferably, this initial value is the magnetic write width which is determined based on the difference between left and right head positions which read half of the maximum signal amplitude. To determine the final magnetic write width, the initial value is adjusted with side reading correction values. The side reading correction values are determined based on left and right side reading “tails” of a bell-shaped signal curve which is formed by the full track profile data when graphed. It is not necessary to obtain the microtrack profile to determine these side reading values.
    Type: Application
    Filed: July 11, 2002
    Publication date: January 15, 2004
    Inventors: Peter Cheng-I Fang, Terence Tin-Lok Lam, Zhong-Heng Lin
  • Publication number: 20030179478
    Abstract: A nonlinear transition shift (NLTS) measurement procedure for read/write heads employing a giant magnetoresistive (GMR) merged heads. The method of this invention includes the pulse-shape distortion effects on recording nonlinearity, which can significantly affect the existing theoretical formulae for calculating nonlinearity correction factor from measured partial erasure values, and second-order approximation of equation of NLTS and nonlinearity correction factor. Transition broadening effects (TBE) and partial erasure (PE) are incorporated in the NLTS measurement procedure to permit accurate isolation of the NLTS from the unrelated TBE/PE and GMR nonlinear transfer characteristic (NTC). First, a fifth harmonic elimination (5HE) test is performed at bit period T to measure a first nonlinearity value X.
    Type: Application
    Filed: March 21, 2002
    Publication date: September 25, 2003
    Applicant: INTERNATIONAL BUSINESS MACHINES CORPORATION
    Inventors: Peter Cheng-I Fang, Xiangjun (Leon) Feng, Terence Tin-Lok Lam, Zhong-Heng Lin