| 摘要 |
<p>PURPOSE:To obtain a circuit for stably outputting an auto-tracking locking signal even when the level of an error voltage is sharply changed by counting up the sampling pulses from an auto-tracking circuit and comparing the counted value with a prescribed threshold. CONSTITUTION:A pulse generating circuit 42a is driven by a pulse generated from a head switching pulse generating circuit 12 and inputs its output to a D-type flip flop 42d. A decoder 42b switches a threshold in accordance with an even-times speed signal, an odd-times speed signal and a single-times speed signal. A sampling pulse counter 42c counts up the sampling pulse SP2 of an AND circuit 31. In said constitution, the sampling pulses are counted up, the counted value is compared with a prescribed threshold, and even when the level of an error voltage is sharply changed, the circuit for stably outputting an auto-tracking locking signal can be obtained.</p> |
