A method of STW (servo track write) for improving the quality of the servo tracks
by suppressing the misalignment of the write start position caused by the asynchronous
continuous vibration of a disk drive is disclosed. The disk drive includes a spindle
motor, a disk medium, a write/read head and a head moving mechanism for carrying
out the sector servo operation. The STW method comprises the steps of detecting
the continuous vibration asynchronous with the rotational frequency of the spindle
motor, detecting the phase of the asynchronous continuous vibration detected, determining
the write start sector of each servo track based on the detected phase of the asynchronous
continuous vibration, determining the write start time of each servo track in accordance
with the clock signal, and moving the head onto the servo track where the head
positioning information is written, by the head moving mechanism and writing the
information in the servo track based on the write start time.
