Seagate Technology Incorporated

Ricky WeiWatt Yeo

Xiong Liu

KianKeong Ooi

Beng Wee Quak

Kian Keong Ooi

BengWee Quak

Ming Zhong Ding

ShuangQuan Min

Chiap Heok Ang

Shuang Quan Min

ChiapHeok Ang

A method for writing servo information to a disc rotatably mounted to a spindle motor. A measured cage frequency is obtained from a written reference track, from which an actual cage frequency is predicted. The predicted cage frequency is then used to derive compensated position commands. During a servo write interval, the compensated position commands are used to control the head such that the head follows the disc movements caused by the cage frequency.

Prediction and cancellation of cage frequency in a disc drive

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

Ricky WeiWatt Yeo