Patent GB-1404685-A (GB)
Title: Polychromatic graphic visual display assembly
IPC: G01S7/22
Filed: 1973-05-18
Abstract: 1404685 Cathode-ray tube displays COMPAGNIE INDUSTRIELLE DES TELECOMMUNICATIONS CIT-ALCATEL 18 May 1973 [19 May 1972 1 Sept 1972] 23932/73 Heading H4T In a cathode-ray tube colour display system in which each of a plurality of traces (vectors) is produced in one or more (different) colours, all of the traces, or portions thereof, for which a particular colour is specified, are produced in a first sequence in each display cycle followed in turn, by similar production sequences of the other colours. The invention is particularly concerned with displaying data related to the movement of various craft, e.g. aircraft, the data being derived by known means such as radar and is also concerned with tracing mathematical curves. As shown in Fig. 1, a calculator 6 supplies the data comprising items specifying colour and items specifying parameters of portions of the traces to a main memory 3 in which it is stored in addresses determined by an address register 4. The latter then operates to select the addresses of the data in memory 3 which involve the same colour and to store such addresses in an auxiliary memory 20 in groups of addresses related respectively to the different colours. An address counter 33 then operates memory 20 to supply a "colour" signal to a comparator 28 which also receives an input from a circuit 24 specifying, in sequence, the various colours in which the system operates (e.g. Red, Orange, Yellow and Green) and when the two inputs agree as to colour, an output from comparator 28 blocks an AND gate 32 to prevent register 33 from being advanced by a clock 37.. The address of the "colour" signal from memory 20 then operates in response to a read signal at input 36 of register 4 to cause memory 3 to supply the corresponding trace parameter via output register 5 to a control circuit 7 which causes either a vector generator 8 or a character generator 9 to supply the appropriate beam deflection signals to the display tube 2 via a digital-to-analogue converter 12. When the two inputs to comparator 28 do not agree AND gate 32 is not blocked and clock pulses from clock generator 37 advance register 33 until an address is reached at which the "colour" information input to comparator 28 is the same as the colour specifying signal from circuit 24 when the operation continues as deserted above. When all of the addresses in memory 20 have been "read" an output from circuit 7 causes the circuit 24 to produce a signal specifying the next colour in the sequence at which all the addresses are again read and this sequence is repeated for the other colours after which the circuit 24 is reset to commence a second sequence of colour specifying signals. The display tube 2 is of the kind in which the reproduced colour is determined by the energy of the electrons in the scanning beam (Penetration type) this being determined by control of the potential of the cathode 16 via a device 15 in accordance with outputs from the circuits 7 and 24. In order to reduce the programming requirements concerned with the position of the beam when colour changes occur the data in digitalto-analogue converter 12 is fed to the memory 20 (Fig. 2, not shown).