| 摘要 |
PURPOSE:To detect a servo sector stably even when the erasing section is short by detecting the servo sector by using outputs of the first and second monostable multivibrators having specified oscillating periods respectively. CONSTITUTION:Signals read out from a magnetic head are sent to the first monostable multivibrator 10 having retriggerable functions through a binary coding circuit 9. If the oscillating period of the monostable multivibrator 10 is set at about double servo clock period, an output waveform (b) becomes a low level first in the erasing section. When the oscillating period of the second monostable multivibrator 11 is about a half the 1 sector period, an output (c) becomes a high level in the servo sector area excepting the erasing section, and a signal (d), the logical sum of the signals (b) and (c), becomes a servo sector detecting signal. The logical sum of outputs (b) of monostable multivibrator 10 and outputs (e) of a pulse circuit 15 is obtained, and only the erasing section is used for servo sector detection as an input of the monostable multivibrator 11. |
