Dual deck vcr and duplicating circuit therefor

Abstract

A dual deck video cassette recorder, having first and second video decks in a common housing. Each deck has a plurality of heads and both of the decks can playback, and at least one of the decks can record. A switch arrangement is connected to both decks to provide for selective connections of video and audio signals between, and from the inputs to and outputs from, the two decks. A sensor detects the angular position of the heads of each deck to assure they are in phase prior to initiating recording. A mechanism corrects the angular position of the heads of at least one of the decks to assure the heads of each will be in the same angular phase prior to initiating recording. A circuit detects a copy protection signal on a tape in one deck during vertical blanking and the signal is located and timed so that it will not interfere with normal operation of the video signals, to produce a quality picture on a TV monitor or place information onto tape in one deck which provides a quality picture. A circuit is provided for ceasing, and preventing, any copying function being performed when the copy protection signal has been detected, and it also determines, after the copy protection signal has be detected, that the signals at both decks have been synchronized for a predetermined period of time.