SERVO-SIGNAL WRITING METHOD, MAGNETIC DISK DEVICE AND MAGNETIC DISK

PURPOSE:To prevent occurrence of phase deviation between tracks, and eccentricity of a disk by providing a clock signal on a magnetic disk, and performing reproduction of clocks and the recording of a servo signal with the same magnetic head. CONSTITUTION:A magnetic head 2 reprodcues an already recorded clock signal. The signal is amplified with an amplifier 8. A write-clock generating circuit 9 generates a recording clock for servo-pattern recording. A write-pattern generating circuit 11 generates a pattern, which is written into a magnetic disk 3, based on the recording clock outputted from the circuit 9 and the pattern outputted from a controller 12. The pattern is recorded on the magnetic disk 3 through a writing circuit 10. Then, the magnetic head 2 is sent by a head- position control mechanism 7, and the above described process is repeated. Here, the control mechanism also has the length measuring function when the magnetic head 2 is moved.