Patents by Inventor Chun Sei Tsai

Chun Sei Tsai 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: 7212374
    Abstract: Disclosed is a disk drive to characterize misaligned servo wedges. A disk of the disk drive includes a plurality of circumferential tracks, in which, each track includes a plurality of servo wedges spaced sequentially around the circumference of the track wherein the servo wedges may be misaligned relative to the head of the disk drive that moves about a pivot. A servo controller is used to characterize the misaligned servo wedges relative to the head during a seek operation by implementing the following operations: commanding the head to perform a seek operation from a starting track to an ending track; obtaining samples of wedge-to-wedge time (WTWT) values corresponding to time intervals between identified servo wedges for sampled tracks traversed during the seek operation; calculating WTWT variations for each sample; and calculating a calibrated misalignment value for each sample based upon WTWT variations.
    Type: Grant
    Filed: October 14, 2005
    Date of Patent: May 1, 2007
    Assignee: Western Digital Technologies, Inc.
    Inventors: Zhi Wang, Jenghung Chen, Chun Sei Tsai, Carl E. Barlow
  • Patent number: 7209310
    Abstract: A disk drive is disclosed comprising a disk having a plurality of servo sectors defining a plurality of servo tracks, wherein each servo sector comprises a track address identifying a corresponding servo track. A head is actuated over the disk, and a ramp is positioned near an outer diameter of the disk, wherein an edge of the ramp extends over a plurality of the servo tracks. The head is loaded from the ramp onto the disk, and a track address in at least one of the servo sectors is detected and stored. The process is repeated a number of times, and then a starting track proximate an outer diameter of the disk is identified in response to the detected and stored track addresses.
    Type: Grant
    Filed: July 25, 2005
    Date of Patent: April 24, 2007
    Assignee: Western Digital Technologies, Inc.
    Inventors: Chun Sei Tsai, Ngoc Le, Jenghung Chen, Hien Chu