GB864024A - Apparatus for the visual representation of symbols on the screen of cathode ray tubes - Google Patents

Abstract

864,024. Cathode-ray tube circuits. WERK FUR SIGNAL-UND SICHERUNGSTECHNIK BERLIN VEB. June 3, 1957, No. 17567/57. Class 40(7) A visual representation of numerals is displayed on the screen of a cathode-ray tube by producing appropriate Lissajous figures from sinusoidal voltages having a 1:2 frequency ratio and then blanking out unwanted portions by means of blanking signals dervied from 50 (or 100) c.p.s. sinusoidal voltages by rectification and phase adjustment under the control of a resistance-capacity network. As shown, the initial Lissajous figures are produced by supplying the vertical deflecting plates V (Fig. 1) of the tube with voltages derived from one of the terminals 1, 2, 3 (Fig. 1a), depending on the figure to be produced, these voltages consisting of a 50 c.p.s. sine wave (terminal 1); the positive half-cycles of this sine wave together with an adjustable amount of the negative half-cycles (terminal 2); and the negative half-cycles together with an adjustable amount of the positive half-cycles (terminal 3); and by supplying the horizontal deflecting plates H with either a 100 c.p.s. voltage from terminal 5 or the negative halfcycles of this wave from terminal 4. To complete the formation of a particular figure unwanted portions of the basic Lissajous figure are blanked out by applying blanking signals, selectively, from terminals 6, 8 or 9 (Fig. 1b) to the grid G of the tube, the cathode K being continuously supplied from terminal 7 and the phase of the blanking signals adjusted by means of variable resistors R 3 and R 5 to blank out the undesired portions. The fundamental steps leading to the production of the numeral 5 (Fig. 2e), which is produced by supplying the V and H plates of the tube from terminals 3 and 4 (Fig. 1) respectively and the grid G from terminal 8 (Fig. 1b) are described with reference to the component traces Figs. 2a to 2d.