| 摘要 |
PURPOSE:To detect previously the possibility of an erasure accident of stored information being slightly high by providing a detecting circuit which detects a drop in the voltage of the playback signal which is read out of a disk by a head. CONSTITUTION:When a head 6 floats normally, the voltage of the playback signal of the head 6 from the disk 3 has a normal value, so the output voltage (a) of an amplifier 21 becomes a signal having a waveform with a relatively high crest value. It becomes higher than the output voltage (b) of a reference voltage generating circuit 22 cyclically, the output (c) of a comparator 23 varies periodically, the output (d) of a retrigger one-shot multivibrator 24 becomes a signal with logic 0 at the time of positive logic, so that no detection signal with logic 1 is outputted. When the head 6 and disk 3 begin to damage, the output voltage (a) of an amplifier 21 becomes invariably lower than the output voltage (d) of the reference voltage generating circuit 22. Then, the output (c) does not vary any more and the output (d) is outputted as a detection signal with logic 1. |
