Seagate Technology Incorporated

ChiapHeok Ang

Xiong Liu

Karl Arnold Belser

KianKeong Ooi

Gabor Szita

BengWee Quak

ShuangQuan Min

Ricky WeiWatt Yeo

The present invention proposes a new servo track writing technique called Extended Copying with Head Offset (&ldquo;ECHO&rdquo;). The read and write elements of the read/write head are offset from each other. A servo writer writes a guide pattern on the magnetic media disc. ZAP correction factors are added to the guide pattern. The head disc assembly is then connected to an electrical control system for self-propagating servo writing. The actuator arm is displaced until the read head is aligned over the guide pattern. A new servo track is written by the write element. ZAP correction factors are added to the newly written servo track. The actuator arm is displaced until the read element is aligned with the newly written servo track. A new servo track is written. ZAP correction factors are added to the newly written servo track. The process is repeated until a desired number of servo tracks are written.

Servo track writing using extended copying with head offset

The magnitude and frequency of runout due to vibration of the cage of the spindle motor is detected. A plurality of servo patterns are written to a reference track having a clock pattern on the disc, and the plurality of servo patterns are then read over a plurality of revolutions of the disc using a clock head. The magnitude of position error of the clock head relative to the reference track is identified for each of the read servo patterns. The magnitude and frequency of runout due to cage vibration is identified from the position errors. Servo patterns are written to user tracks on the disc by identifying periods of low magnitude runout due to cage vibration, and writing the servo patterns to the user track during those periods of low magnitude runout.

Detection and cancellation of cage frequency using the clock head in a servowriter

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Singapore, Singapore

ChiapHeok Ang