Patent ID: 6904010

Claim:
A method of writing at least a servo track in recording tracks of a disk file apparatus comprising at least one disk medium rotated by a spindle motor, a head for writing and reading the data on and from said, disk medium, and at least a head moving mechanism, said disk medium having a recording surface formed with concentric recording tracks segmented into a plurality of sectors each having written therein the positioning information for said head in advance, said method comprising the steps of: detecting continuous vibration of the medium, said continuous vibration being asynchronous with the rotational frequency of said spindle motor; detecting the phase of the detected asynchronous continuous vibration; determining the write start sector or the write end sector or the write start time or the write end time of each servo track based only on said detected phase of the asynchronous continuous vibration; and moving said head by said head moving mechanism on said recording surface where said head positioning information is to be written and writing said information based on said write start sector or said write end sector, the method further comprising the steps of: detecting the rotational frequency of said spindle motor; writing the head positioning information for a predetermined number of tracks in advance on said disk medium by the conventional servo track write method; detecting the phase of the head position signal output by reading, using the same head, said predetermined number of the tracks having written therein said head positioning information; and measuring the phase difference between the phase of said head position signal output and the phase of said asynchronous continuous vibration; wherein said step of determining the write start sector or the write end sector includes the substep of setting a servo track write start position [(1−fc/fr)×180]° behind the phase of the peak amplitude of said asynchronous continuous vibration in the case where fc<fr, and a servo track write start position [(fc/fr−1)×180]° ahead of the phase of the peak amplitude of said asynchronous continuous vibration in the case where fc>fr, where fc is the frequency of said asynchronous continuous vibration and fr is the rotational frequency of said spindle motor.