SYSTEM ZUR FARBUEBERTRAGUNG VON ZEICHEN

1466422 Cathode-ray tube displays NIPPON ELECTRIC CO Ltd 15 March 1974 [15 March 1973] 11665/74 Heading H4T In a system for transmitting computer generated colour graphic characters a character representing video signal is transmitted over a first path and a colour-determining digital signal is transmitted over a second path. The transmitter includes a video encoder responsive to input data from a digital store to produce the video signal and a colour signal generator responsive to the input data to produce the colour-determining signal in the form of a synchronizing pulse timed with respect to the video signal and followed by a sequence of colour determining binary code pulses. Horizontal and vertical synchronizing signals are added to the video signal and at the receiver a decoder responsive to the colour-determining signal reproduces the sequence of code pulses as a parallel binary signal and this together with the video signal is supplied to a colour display unit. With this arrangement there is substantially no mutual phase shift between the respective (Red, Green and Blue) colour signals and any difference in the lengths of the transmission paths (cables) is compensated by an adjustable delay line which controls the instant at which the parallel binary colour signal (derived by the receiver decoder) is combined with the video signal to form the composite signal supplied to the display unit. The whole operation is described with respect to block and other circuit diagrams together with the waveforms operative at various points in the circuits.