A television camera is adapted to be coupled to an external video device, such as a video tape recorder (VTR) or a camera control unit (CCU) linking it with other cameras. The output video signals from the cameras and VTR can be sequentially switched, mixed, or superimposed automatically to provide special...http://www.google.es/patents/US4340903?utm_source=gb-gplus-sharePatente US4340903 - Television camera
