PICTURE EXCHANGING SYSTEM

PURPOSE:To prevent the disturbance of reception screen of the picture terminal due to the exchange connection. CONSTITUTION:A picture exchange device 10 provided with a synchronous signal generating means 100 generating a vertical synchronizing signal S to a picture signal V to be outputted from a picture providing equipment 20 and supplying it to the picture supply equipment and a picture exchange switch 1 connecting the picture supply equipment and a picture terminal 30 is provided with a free area informing means 200 transmitting a control enable signal EC indicating the time region without including information required to display one field in the picture terminal among picture signals to be outputted from the picture supply equipment as a reference while taking the vertical synchronizing signal to be generated as the synchronous signal generation means and permitting the exchange connection to a picture exchanging switch only during the reception of the control enable signal.