| 摘要 |
PURPOSE:To prevent a malfunction by detecting the amplitude of a servo signal written on the track of a magnetic disk, comparing the sum with a prescribed value so as to discriminate the presence or absence of the flaw of a servo signal part. CONSTITUTION:Servo signals A, B on the track of a magnetic disk are detected with a read circuit 11 by a head 10, a peak value is detected by a peak detection circuit 12, arithmetic samples a, b are extracted by a sample circuit 13, the result is given to an arithmetic circuit 14 to calculate the relation of a+b=k. Then a median KC is obtained from plural servo signals K1-Kn, the tolerance sigma is added to set K'C=kC+ or -sigma and it is compared with the value K. When it is decided the K is normal, a deviation from the track center line is fed to a motor 16 by a phase control circuit 15 between the values (a) and (b) to apply the position control to the head 10.
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