Chun Sei Tsai from Tustin, CA, age 63

Us Patents

Disk Drive Identifying Starting Track By Performing Multiple Load Operations
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US Patent:

7209310, Apr 24, 2007
Filed:

Jul 25, 2005
Appl. No.:

11/188947
Inventors:

Chun Sei Tsai - Tustin CA, US
Ngoc Le - Fountain Valley CA, US
Jenghung Chen - Cupertino CA, US
Hien Chu - Santa Ana CA, US
Assignee:

Western Digital Technologies, Inc. - Lake Forest CA
International Classification:

G11B 21/02
US Classification:

360 75, 360 7808
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.

Disk Drive To Characterize Misaligned Servo Wedges
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US Patent:

7212374, May 1, 2007
Filed:

Oct 14, 2005
Appl. No.:

11/250649
Inventors:

Zhi Wang - San Jose CA, US
Jenghung Chen - Cupertino CA, US
Chun Sei Tsai - Tustin CA, US
Carl E. Barlow - Lake Forest CA, US
Assignee:

Western Digital Technologies, Inc. - Lake Forest CA
International Classification:

G11B 5/596
G11B 21/02
US Classification:

360 7814, 360 7804
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.

Disk Drive Returning Dummy Data To A Host When Reading An Unwritten Data Sector
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US Patent:

7852596, Dec 14, 2010
Filed:

Feb 25, 2009
Appl. No.:

12/392822
Inventors:

William B. Boyle - Lake Forest CA, US
Chun Sei Tsai - Tustin CA, US
Assignee:

Western Digital Technologies, Inc. - Lake Forest CA
International Classification:

G11B 21/02
G11B 5/09
G11B 27/36
US Classification:

360 75, 711111, 711165, 360 53, 360 51, 360 31, 360 55
Abstract:

A disk drive is disclosed comprising a disk and a head actuated over the disk. The disk comprises a plurality of tracks, wherein each track comprises a plurality of data sectors. A read command is received from a host to read data from a target data sector. When it is determined that the target data sector has not been written by the host, dummy data is returned to the host.

Disk Drive Prioritizing In-The-Field Defect Scanning Based On Number Of Write Operations In Each Of A Plurality Of Defect Zones
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US Patent:

7929234, Apr 19, 2011
Filed:

Mar 27, 2009
Appl. No.:

12/413408
Inventors:

William B. Boyle - Lake Forest CA, US
Chun Sei Tsai - Tustin CA, US
Anthony L. Pei - Irvine CA, US
Assignee:

Western Digital Technologies, Inc. - Irvine CA
International Classification:

G11B 27/36
US Classification:

360 31, 360 53
Abstract:

A disk drive is disclosed comprising a head actuated over a disk, the disk having a plurality of data tracks, wherein a first plurality of data tracks comprises a first plurality of defect scanned data sectors and a second plurality of data tracks comprises a second plurality of unscanned data sectors. The second plurality of data tracks is divided into a plurality of defect zones. A first number of write commands are received from a host to write data to a first defect zone. A first data sector in the first defect zone is defect scanned in response to the first number of write commands to the first defect zone.

Disk Drive Storing Parameters Of A Write Operation In A Plurality Of Data Sectors
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US Patent:

7933087, Apr 26, 2011
Filed:

Jun 18, 2008
Appl. No.:

12/141693
Inventors:

Chun Sei Tsai - Tustin CA, US
William B. Boyle - Lake Forest CA, US
Carl E. Barlow - Lake Forest CA, US
Assignee:

Western Digital Technologies, Inc. - Irvine CA
International Classification:

G11B 5/09
US Classification:

360 48
Abstract:

A disk drive is disclosed comprising a disk having a plurality of data sectors, and a head actuated over the disk. The disk drive further comprises control circuitry operable to execute a write operation for writing data to the disk. A first part of the data is written to a first data sector together with a first sector signature data (SSD) record comprising a first parameter of the write operation and a first id that identifies the first parameter. A second part of the data is written to a second data sector together with a second SSD record comprising a second parameter of the write operation and a second id that identifies the second parameter.

Disk Drive Refreshing Zones In Segments To Sustain Target Throughput Of Host Commands
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US Patent:

7945727, May 17, 2011
Filed:

Jul 27, 2007
Appl. No.:

11/829819
Inventors:

Michael S. Rothberg - Foothill Ranch CA, US
William B. Boyle - Lake Forest CA, US
Chun Sei Tsai - Tustin CA, US
Assignee:

Western Digital Technologies, Inc. - Irvine CA
International Classification:

G06F 12/00
US Classification:

711112, 711106, 711167, 710 45, 710 58
Abstract:

A disk drive is disclosed including a disk comprising a plurality of refresh zones, and a head actuated over the disk. The disk drive further comprises control circuitry for receiving access commands from a host. The control circuitry refreshes a refresh zone in a plurality of segments with an interval between each segment, and processes at least one of the access commands during the interval between at least two of the segments, wherein a size of each segment and the interval ensures an average throughput of access commands received from the host does not fall below a first threshold.

Disk Drive Biasing Refresh Zone Counters Based On Write Commands
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US Patent:

7974029, Jul 5, 2011
Filed:

Jul 31, 2009
Appl. No.:

12/533950
Inventors:

Chun Sei Tsai - Tustin CA, US
Sang Huynh - Corona CA, US
Anthony L. Pei - Irvine CA, US
Don Brunnett - Pleasanton CA, US
Jahangir John Kasraee - Irvine CA, US
Kent W. Gibbons - Trabuco Canyon CA, US
Assignee:

Western Digital Technologies, Inc. - Irvine CA
International Classification:

G11B 27/36
US Classification:

360 31, 360 48, 360 53, 360 62
Abstract:

A disk drive is disclosed comprising a disk comprising a plurality of tracks, and a head actuated over the disk. A plurality of refresh zones are defined, wherein each refresh zone corresponds to a plurality of the tracks. Data is written to a first refresh zone, and a first zone counter is updated for a second refresh zone at a first rate. Data is written to a third refresh zone, and the first zone counter is updated for the second refresh zone at a second rate different than the first rate.

Disk Drive Employing Different Servo Tpi To Data Tpi Ratios Across The Disk Surface
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US Patent:

7982993, Jul 19, 2011
Filed:

Dec 19, 2008
Appl. No.:

12/340309
Inventors:

Chun Sei Tsai - Tustin CA, US
William B. Boyle - Lake Forest CA, US
Carl E. Barlow - Lake Forest CA, US
Assignee:

Western Digital Technologies, Inc. - Irvine CA
International Classification:

G11B 5/09
G11B 5/596
US Classification:

360 48, 360 7708
Abstract:

A disk drive is disclosed having a first disk surface, and a head actuated over the first disk surface. The first disk surface comprises a plurality of servo tracks and a plurality of data tracks. The data tracks of the first disk surface are banded together into a plurality of data zones, including a first data zone and a second data zone. A first servo tracks per inch (STPI) to data tracks per inch (DTPI) ratio of the first data zone is substantially different from a second STPI to DTPI ratio of the second data zone.