| 摘要 |
PURPOSE:To prevent mis-detection of out-of-track by comparing a track error signal during write with a stored track error signal at the write and outputting an out-of-track signal only when there is a clear difference between the both, and a reference range is exceeded during the write operation. CONSTITUTION:The signal amplitude of the track error signal (a) is compared with a voltage (v) corresponding to a track error specified range, and when it is exceeded, a comparator output (b) goes to '1' level. Then the track error signal (a) is converted into a digital value by an A/D converter 3 and stored in a storage circuit 4 over one turn synchronously with the turning period of the track according to a read signal (g) only at the read operation of the titled device. The output of the storage circuit 4 is supplied regardless of the read/ write of the device and fed to a D/A converter 5, where the signal is converted into an analog track error signal (c), and the track error signal (c) and the track error signal (a) are subtracted by a differential amplifier 6 to obtain an error signal (d). The error signal (d) is compared with the voltage (v) corresponding to the reference voltage range by a voltage comparator 7.
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