| 摘要 |
A method for writing patterns on a medium, especially self servowriting a rotating disk in a disk drive including a servo controlled actuator for positioning the head radially with respect to the disk, in which a position error signal equals a difference between a reference waveform and a measured relative position waveform derived from readback signals from the head interacting with the disk, including writing servo patterns on successive radial tracks of the disk using the actuator and deriving the reference waveform as a function of closed loop transfer function of the actuator and at least one measured position waveform. The frequency dependent gain of the servo loop may be set so that closed loop response of the servo loop has a magnitude less than unity at every integer multiple of disk rotation frequency, yet is high enough to provide substantial reduction of mechanical disturbances. Writing a series of first patterns along a track, displacing the head a known fraction of a track to a displaced position, and reading from selected ones of the first patterns position information for determining deviation information representative of deviation of the head from the known fraction, and using the deviation information to propagate second patterns at the displaced position with the deviation information encoded in the patterns. Spacing between adjacent tracks can be adjusted without writing the entire disk. Deviations in demodulated position signal arising from random placement errors in servo patterns may be cancelled. Apparatus for performing the methods and disk drives written by the method. <IMAGE>
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