GB1147060A - Generation and reproduction of characters - Google Patents

Abstract

1,147,060. Cathode - ray tube displays. PHILIPS ELECTRONIC & ASSOCIATED INDUSTRIES Ltd. 27 Oct., 1966 [30 Oct., 1965], No. 48190/66. Heading H4T. An arrangement for generating and displaying characters utilizes a magnetically deflected cathode-ray display tube 1 supplied with beam bright-up pulses from a magnetic core character generator matrix 6 in which the character is " written " by selector means 9 and a complete scan of the horizontal rows of which is produced by vertical selector means 11 for each selection of a vertical column by horizontal selector 10. The characters, which are stored in digit form in a plurality of registers in a memory 13, are transferred to a buffer stage 12 by the output of stage 1 of selector 10 and are then " written " in to matrix 6 by the output of stage 2. During the operation of each of stages 3 to 7 a complete scan is effected by selector 11 and the resulting output pulses, depending on the character " written " are supplied to the beam intensity control electrode via amplifier 8. Each operation of stage 8 of selector 11 initiates the fly-back of a vertical line scan generator 3 so that the character is reproduced as a pattern of bright dots in a 7 x 5 matrix. At the end of each cycle of selector 10 the output of stage 8 is supplied to an AND gate 16, and this together with the "1" output of a bi-stable trigger 17 causes a digit selector 15 to step-on one count, this operation continuing until all the characters in the selected register have been displayed. Each character is spaced from the next by an amount determined by the time of operation of stages 1 and 2 of selector 10 and the contents of a register are displayed in a horizontal trace during a single sweep of the horizontal deflection generator 4. When all the characters (digits) in one register have been displayed selector 15 which will have reached a full count, then supplies a pulse which causes selector 14 to select a new register and switches trigger 17 to the "0" state. This initiates the fly-back of generator 4 and during this period the tube beam is blanked by the "0" output supplied to a modulation circuit 5. The blanked condition is maintained for the duration of three cycles of selector 10 by supplying the output of stage 8 via an AND gate 18, also receiving the "0" output of trigger 17, to a threepulse counter 19, the output of which then switches 17 to the "1" state and a new cycle commences. The next horizontal line of characters is then traced at a different vertical level by utilizing an output from selector 14 to control the application of shift signal from means 20 to the vertical deflection coils in scanning yoke 2.