Automatic phase adjusting apparatus for television cameras

Claim 1

In a system for producing a composite video signal for broadcasting by switching, mixing and composing a plurality of composite video signals supplied from a plurality of television cameras, an apparatus for automatically adjusting phases of the plurality of composite video signals comprising commonly for the plurality of television cameras a circuit for generating a reference composite synchronizing signal and a reference subcarrier signal; and for the respective television cameras a circuit for separating a composite synchronizing signal from the composite video signal supplied from the related television camera at a cross point; a circuit for separating a burst flag signal from the composite video signal at the cross point; a circuit for detecting a first phase difference between said separated composite synchronizing signal and the reference composite synchronizing signal; a circuit for shifting the phase of the reference composite synchronizing signal in accordance with the detected first phase difference in such a manner that the detected first phase difference becomes a predetermined value; a circuit for detecting a second phase difference between said extracted burst flag signal and the reference subcarrier signal; a circuit for shifting the phase of the reference subcarrier signal in accordance with the detected second phase difference in such a manner that the detected second phase difference becomes a predetermined value; a circuit for deriving a burst flag signal from the phase shifted reference subcarrier signal, said burst flag signal having a corrected phase relation with respect to the phase shifted reference composite synchronizing signal; and a circuit for combining the derived burst flag signal and the phase shifted reference composite synchronizing signal to generate a synchronous coupling black burst signal to be supplied to the related television camera.