Apparatus for producing a phase-synchronized reference signal in a video

Abstract

Apparatus is disclosed for use in a video signal reproducing system of the type having first and second rotary reproducing transducers for reproducing video and vertical synchronizing signals from record tracks on a record medium, in which the transducers exhibit a predetermined angular separation therebetween, the video signal reproducing system also having means for producing a reference synchronizing signal in phase synchronism with the vertical synchronizing signal reproduced by the first transducer. The apparatus is adapted to produce a substantially phase synchronized reference signal regardless of the particular transducer which is used to reproduce the video signals. The apparatus comprises a delay circuit for delaying the reference synchronizing signal by an amount corresponding to the predetermined angular separation between the transducers; and a switching circuit supplied with this delayed as well as the undelayed reference synchronizing signal. A switch control circuit supplies a switch control signal to the switching circuit to determine whether the delayed or undelayed reference synchronizing signal should be selected, the switch control circuit including a detector for detecting the phase relationship between the vertical synchronizing signal which then is being reproduced and the reference synchronizing signal.