Patents by Inventor HengChang Guo

HengChang Guo 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: 10629234
    Abstract: A data storage device is disclosed comprising a head actuated over the disk. A first notch filter is calibrated at a first temperature, and a second notch filter is computed for a second temperature based on the first notch filter and a first delta temperature between the first temperature and the second temperature. The second notch filter is computed by transforming a continuous-time transfer function of the first notch filter adjusted by the first delta temperature into a discrete-time transfer function of the second notch filter.
    Type: Grant
    Filed: June 27, 2019
    Date of Patent: April 21, 2020
    Assignee: Western Digital Technologies, Inc.
    Inventors: Hengchang Guo, Tetsuo Ueda, Chuanwen Ji, Alexander Babinski, Shinsuke Nakagawa
  • Patent number: 8797664
    Abstract: Determining a polarity of a piezoelectric (PZT) actuator of a disk drive including a disk for storing data and a head for reading and writing data. A test signal is injected into the PZT actuator and a position signal is received which indicates a position of the head over the disk resulting from the test signal. A test compensation signal is generated based on the received position signal and the polarity of the PZT actuator is determined based on a phase of the generated test compensation signal.
    Type: Grant
    Filed: December 22, 2012
    Date of Patent: August 5, 2014
    Assignee: Western Digital Technologies, Inc.
    Inventors: Hengchang Guo, Duc T. Phan, Yanan Huang, Chuanwen Ji, Yakov M. Lifschitz
  • Patent number: 8743503
    Abstract: A disk drive is disclosed comprising a head actuated over a disk comprising a plurality of servo tracks defined by servo sectors. The head is positioned over a first servo track, and a first position error signal (PES) by reading a first servo sector during a first revolution of the disk and in response to a first compensation value. A second compensation value is updated for a second servo sector based on the first PES during the first revolution of the disk. A second PES is generated by reading the second servo sector during the first revolution of the disk and in response to the updated second compensation value. The first compensation value is updated for the first servo sector based on the second PES during the first revolution of the disk. The head is actuated over the disk in response to the first PES and the second PES.
    Type: Grant
    Filed: March 11, 2013
    Date of Patent: June 3, 2014
    Assignee: Western Digital Technologies, Inc.
    Inventors: Shan Tang, Hengchang Guo
  • Patent number: 8553351
    Abstract: A disk drive is disclosed comprising a head actuated over a disk, the disk comprising a plurality of servo tracks defined by a plurality of servo sectors. An estimated radial location of the head is generated in response to an actuator control signal. A Gray coded track ID is detected from reading a servo sector, and decoded into a detected track ID. A burst position error signal (PES) is generated from reading servo bursts in the servo sector, wherein the burst PES represents a detected fractional servo track offset of the head. When the detected track ID is corrupt, a corrected track ID is generated using the estimated radial location and the burst PES, and the actuator control signal is adjusted in response to the corrected track ID and the burst PES.
    Type: Grant
    Filed: October 6, 2011
    Date of Patent: October 8, 2013
    Assignee: Western Digital Technologies, Inc.
    Inventors: Aswartha Narayana, Chuanwen Ji, Duc T. Phan, Min Chen, Hengchang Guo
  • Patent number: 7295395
    Abstract: A motion pattern of an actuator supporting a head is monitored during/after a disc spin-up. The monitor's signal is configured to generate a digital indication of where the head was just before the spin-up. The digital indication is optionally a single-bit indicator that is used directly as a decision of whether to continue a start-up operation.
    Type: Grant
    Filed: March 12, 2004
    Date of Patent: November 13, 2007
    Assignee: Seagate Technology LLC
    Inventors: ChoonHoe Koh, HengChang Guo, WaiKhay Chan, JiaHong Shu, KianKeong Ooi, KianSoon Yeo, BengWee Quak, YuNang Zai, Kong Yaw Lucas Lee
  • Publication number: 20050201000
    Abstract: A motion pattern of an actuator supporting a head is monitored during/after a disc spin-up. The monitor's signal is configured to generate a digital indication of where the head was just before the spin-up. The digital indication is optionally a single-bit indicator that is used directly as a decision of whether to continue a start-up operation.
    Type: Application
    Filed: March 12, 2004
    Publication date: September 15, 2005
    Inventors: ChoonHoe Koh, HengChang Guo, WaiKhay Chan, JiaHong Shu, KianKeong Ooi, KianSoon Yeo, BengWee Quak, YuNang Zai, Kong Lee
  • Patent number: 6873490
    Abstract: Method and apparatus for moving a control object, such as a data transducing head in a data storage device, from an initial position to a destination position. A base generation term describes a normalized trajectory (acceleration, velocity, displacement) of the control object away from the initial position and toward the destination position. A control profile is determined in relation to the base generation term as well as in relation to an acceleration distance and an acceleration time, respectively characterized as a displacement distance and an elapsed time during which the control object is accelerated. The control object is then moved in relation to the control profile. The base generation term is preferably stored in a table which is accessed and scaled in relation to the displacement distance (seek length) for the control object.
    Type: Grant
    Filed: June 19, 2003
    Date of Patent: March 29, 2005
    Assignee: Seagate Technology LLC
    Inventors: HengChang Guo, ChoonHoe Koh
  • Publication number: 20040070863
    Abstract: Method and apparatus for moving a control object, such as a data transducing head in a data storage device, from an initial position to a destination position. A base generation term describes a normalized trajectory (acceleration, velocity, displacement) of the control object away from the initial position and toward the destination position. A control profile is determined in relation to the base generation term as well as in relation to an acceleration distance and an acceleration time, respectively characterized as a displacement distance and an elapsed time during which the control object is accelerated. The control object is then moved in relation to the control profile. The base generation term is preferably stored in a table which is accessed and scaled in relation to the displacement distance (seek length) for the control object.
    Type: Application
    Filed: June 19, 2003
    Publication date: April 15, 2004
    Inventors: HengChang Guo, ChoonHoe Koh