In a television receiver, a video signal for a single frame at any moment is stored in a storage tube. The stored video signal is displayed, if necessary, as a still picture on a part of the picture tube screen together with the ordinary broadcasted television picture in motion....http://www.google.de/patents/US3943280?utm_source=gb-gplus-sharePatent US3943280 - Television receiver with zoom storage tube frame grabber with electronic inset into continuing received video stream
