JPS6489869A - Vertical synchronization correcting circuit - Google Patents

Abstract

PURPOSE:To improve the longitudinal fluctuation (vertical fluctuation) of the screen at intermittent slow reproduction by providing a means varying a pseudo vertical synchronizing signal generating timing so as to inject the pseudo vertical synchronizing signal to a reproduced video signal at a different position from that at still picture reproduction. CONSTITUTION:A variable monostable multivibrator 17 whose delay is varied by a setting circuit 11 and a fixed monostable multivibrator 18 whose delay is fixed are provided and the monostable multivibrators 17, 18 are switched by using a switch 19 and a head switching signal during tape moving at the intermittent slow reproduction from a head switching pulse generator 15 so as to change the position of the pseudo vertical synchronizing signal into the video signal. Thus, since the pseudo vertical synchronizing signal is injected slower than the still reproduction in case of the SP mode at the intermittent slow reproduction, the pickup of the video signal with a delay by a different head is corrected and in case of thc EP mode, since the pseudo vertical synchronizing signal is injected earlier than that at the still reproduction, the pickup of the video signal earlier by a different head is corrected so as to improve the vertical fluctuation.