US Patent No: 6,700,728

Number of patents in Portfolio can not be more than 2000

Method and disk drive for enhanced performance in the presence of stationary PES outliers

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ALSO PUBLISHED AS: 20020191325
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Abstract

A method and apparatus are provided for enhanced performance in the presence of stationary position error signal (PES) outliers in a direct access storage device (DASD). A plurality of PES samples are obtained from a plurality of servo sectors around a track. Utilizing the PES samples, a normalized outlier value is computed for each of the plurality of servo sectors around the track. The computed normalized outlier values are sequentially stored and compared with a set threshold value. A stationary PES outlier is identified responsive to each stored outlier value being greater than the set threshold value. Each identified stationary PES outlier is utilized during predefined operations of the DASD. During a recalibration mode of the DASD, a different track for feedforward generation is selected to avoid an identified stationary PES outlier. When more than one stationary PES outlier is identified from the servo sectors around a track, then data from the track is reassigned to an alternate track and the flawed track is marked to avoid use for future data storage.

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First Claim

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Patent Owner(s)

Patent OwnerAddressTotal Patents
HITACHI GLOBAL STORAGE TECHNOLOGIES NETHERLANDS B.V.AMSTERDAM1325

International Classification(s)

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Inventor(s)

Inventor Name Address # of filed Patents Total Citations
Ottesen, Hal Hjalmar Rochester, MN 80 1726
Smith, Gordon James Rochester, MN 128 1445

Cited Art

Patent Info (Count) # Cites Year
 
SEAGATE TECHNOLOGY LLC (4)
5,930,068 Detecting servo defects in a disc drive 14 1996
6,243,224 Asynchronous digital demodulator and method for a null-type servo pattern 21 1999
6,611,397 Servo burst pattern defect detection 13 1999
6,469,849 Field ratioing demodulation circuit for a null-type servo pattern 16 2000
 
HGST NETHERLANDS B.V. (3)
6,078,445 Gain control for a dual burst, dual frequency PES servo pattern 14 1997
6,097,559 System and method for detecting head-to-disk contact in-situ a direct access storage device using a position error signal 41 1998
6,226,140 Shock detector in a disk drive servo control system 19 1998
 
PURCHASED PATENT MANAGEMENT LLC (2)
6,545,836 Servo control apparatus and method using absolute value input signals 26 1999
6,594,103 Read channel generating absolute value servo signal 31 1999
 
HITACHI GLOBAL STORAGE TECHNOLOGIES NETHERLANDS B.V. (1)
6,219,198 State estimator alteration for odd sample times in a disk drive servo control system 5 1998
 
INTERNATIONAL BUSINESS MACHINES CORPORATION (1)
5,241,433 Disk drive servo control 33 1992
 
RESEARCH INVESTMENT NETWORK, INC. (1)
5,510,939 Disk drive with adaptive positioning 47 1992

Patent Citation Ranking

Forward Cites

Patent Info (Count) # Cites Year
 
HEADWAY TECHNOLOGIES, INC. (1)
7,787,210 Feed-forward method for repeatable runout cancellation 0 2009

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