GB1326577A - Image-display devices - Google Patents

Abstract

1326577 Cathode-ray tube displays COMPAGNIE INTERNATIONALE POUR L'INFORMATIQUE 18 Nov 1970 [21 Nov 1969] 54847/70 Heading H4T A known symbol (Alphanumeric &c.) display system (Fig. 1) in which image data derived from a computer acts via a logic circuit 5 to control a beam unblanking signal generator 4 the signals from which are supplied to a display cathode-ray tube 1 via a refreshing memory 3 synchronously with the (interlaced) line scanning of the tube and in which a light-pen 9 controls a gate 8 to supply to a register 7 the X, Y coordinates of a point selected by the light-pen for controlling the display via the computer is modified, as shown in Fig. 2, by deriving from the logic circuit 5 additional (coded) signals which identify each symbol being displayed and which are combined with the unblanking signals in mixer 11 and supplied via the refreshing memory 3 to a decoder 12 which feeds the unblanking signals to the tube 1 and the symbol identification signals to the gate 8 so that when the latter is opened in response to an output from the light-pen a signal is produced which is unambiguously related to the actual beam unblanking signals producing the point "aimed" at by the light-pen. The unblanking signals and the symbol identification signals are quantized, the receiver circuit 11 includes a scanning amplifier (Fig. 3, not shown) the refreshing memory may comprise a storage tube and the decoder circuit 12 comprises an analogue-to-digital converter (Fig. 5,. not shown). Images derived from a number of sources, e.g. computers, television-type pick-up devices &c. may be superimposed on the display tube and colour image reproduction is also possible.