Patents by Inventor Jern Khang Tan

Jern Khang Tan 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: 9230592
    Abstract: An apparatus includes: a disk; a spindle motor configured to rotate the disk; and control circuitry with a spindle motor control loop, coupled to the spindle motor, the control circuitry configured to: inject a bandwidth test frequency into the spindle motor control loop, measure an open loop gain of the spindle motor control loop, calculate, using coordinate transformations, an estimated loop bandwidth of the spindle motor control loop based at least on one iteration of the bandwidth test frequency injection and the open loop gain measurement, and generate optimum loop parameters of the spindle motor control loop.
    Type: Grant
    Filed: December 23, 2014
    Date of Patent: January 5, 2016
    Assignee: Western Digital Technologies, Inc.
    Inventors: Zhou Yong, Jie Wan, Shuyu Cao, Jianghong Ding, Jern Khang Tan
  • Patent number: 9214188
    Abstract: A method is disclosed for selecting a rotation speed when servo writing a disk of a disk drive. A gas is injected into a head disk assembly (HDA) comprising the disk. The disk is rotated while reading data from the disk using a head to generate a read signal. A fly height modulation (FHM) of the head is measured in response to the read signal. When the FHM exceeds a threshold, the rotation speed is adjusted. The disk is servo written at the adjusted rotation speed. After servo writing the disk and evacuating the gas from the HDA, the disk is rotated at a normal rotation speed lower than the adjusted rotation speed used to servo write the disk, and manufacturing data is written to the disk at the normal rotation speed.
    Type: Grant
    Filed: March 12, 2010
    Date of Patent: December 15, 2015
    Assignee: Western Digital Technologies, Inc.
    Inventors: Jern Khang Tan, Amar Nath, Boworn Panyavoravaj
  • Patent number: 8792202
    Abstract: A disk drive is disclosed comprising a head and a disk comprising a plurality of servo tracks, wherein each servo track comprises a plurality of servo sectors. The disk drive further comprises control circuitry comprising a servo control system operable to actuate the head over the disk in response to the servo sectors. The disk is rotated at a first speed and the servo sectors are read at a first servo sample frequency to generate first servo samples. The disk is rotated at a second speed different from the first speed and the servo sectors are read at a second servo sample frequency to generate second servo samples. The second servo samples are processed to measure a frequency response of the servo control system proximate the first servo sample frequency.
    Type: Grant
    Filed: August 29, 2013
    Date of Patent: July 29, 2014
    Assignee: Western Digital Technologies, Inc.
    Inventors: Jie Wan, Xiaotian Xu, Shuyu Cao, Jern Khang Tan, Guoxiao Guo, Wei Xi