| 摘要 |
PURPOSE:To detect the radial size of drop-out by an apparatus wherein drop-out signals are counted through RS-FF using the comparative output between a signal which is obtained by attenuating a voltage signal per one rotation time of disc and saw teeth wave voltage due to the drop-out signal. CONSTITUTION:A sensor attached to a disc driving motor sents a pulse (a) per one rotation thereof to a monomultiplier 11. Falling of a sample pulse as output from the monomultiplier 11 causes a monomultiplier 12 to generate a reset pulse (c). The pulse (c) is used to generate a saw teeth wave (d) from a saw teeth wave generating circuit 13. The voltage of the saw teeth wave is sample-held by a sample-holding circuit 14 to obtain a voltage (e) per one rotation time. Meanwhile, a drop-out signal (f) is compared with the reference voltage in a comparator 15 and then turned to a saw teeth wave (j) through a Schmitt inverter 16, RS-FF17, monomultiplier 18 and a saw teeth wave generating circuit 20. The saw teeth wave (j) is compared with a signal (k), which is obtained by slightly reducing the signal (e) at 21,in a comparator 22. The resultant signal drives an FF17 through a monomultiplier 23, so that drop-out pulses (i) are counted at 19. |
