| 摘要 |
<p>PURPOSE:To correct a time-axis variation error in a horizontal scanning period, by controlling the turning speeds and/or rotary phases of rotary heads during slow- motion reproduction. CONSTITUTION:Change-over switches 11 and 24 are placed at sides 11b and 24b during standard mode reproduction and at sides 11d and 24c during slow-motion reproduction. An FM video signal having been recorded on a magnetic tape 1 yet is reproduced by rotary heads 3a and 3b and a signal separated by a horizontal synchronizing signal separating circuit 21 is applied to an AFC circuit 23, whose output is applied to a discriminator control system 12 via two stages, each consisting of an amplifier and a limiter, to constitute a closed loop which controls the turning speed of a drum motor 4. Since the signal is passed through those two combination stages of amplifiers and limiters, a large phase error voltage is obtained, and this large voltage controls the drum motor to correct an error in reproduction horizontal scanning frequency during the slow-motion reproduction.</p> |
