Video signal processing apparatus for displaying stored video signal during channel selection

A video signal processing apparatus for a television receiver displaying signals of the extended definition television system comprising:

• receiving means for receiving a video signal;
• scan line converter means including memory means for changing a scan lien frequency of said video signal into a scan line frequency of said extended definition television system and storing a frame of a converted signal in the memory means;
• means for supplying said signal having a changed scan line frequency and stored in the memory means to a display;
• external signal input means for receiving an external video signal;
• switching means for selectively transmitting said video signal from said receiving means or said external video signal received by said external signal input means to said scan line converter means;
• a non-signal detecting circuit connected to an output of said switching means and producing an output signal indicating whether a video signal is present at said output of said switching means;
• and
• control means responsive to user input of input signal information for supplying a control signal to said switching means and to said memory means so that said switching means switches between said receiving means and said external signal input means and said memory means transmits said video signal stored therein to said means for supplying during a prescribed period, such that after said period expires said memory means no longer transmits said video signal stored therein to said means for supplying, said control means being further responsive to said output signal form said non-signal detecting circuit to control said switching means to transmit said video stored in said memory means of said scan line converter when a non-signal condition is detected by said non-signal detecting circuit.