GB900929A - Improvements in character display arrangements - Google Patents

Abstract

900,929. Cathode-ray tube circuits. STANDARD TELEPHONES & CABLES Ltd. April 10, 1959 [April 16, 1958], No. 12215/59. Addition to 830,804. Class 40 (7). A character display arrangement wherein each character is formed on an array of areas of a display device by exciting a selected combination of areas comprises a source of information representing characters, a counting arrangement having an output individual to each area of the array, a first diode matrix having a set of inputs coupled to the information source for receiving a pulse train representative of any one of the characters, each matrix output being individual to a different one of the characters, gating means coupled between the outputs from the matrix and the display device, and a second diode matrix having a set of inputs coupled to separate outputs from the counting arrangement and having outputs coupled to the gating means, each output of the second matrix being individual to a different character and adapted to pass to the display device the pulse combination for that character when the gating means is conditioned in a manner significant to that character. The embodiment relates to the display of characters on a cathode-ray tube (C.R.T.) screen by the intensity-modulation of the C.R.T. beam at the requisite points of a 5Î7 raster, Fig. 8. In the circuit diagram all lines shown interconnecting rows and columns of a matrix contain a diode poled in the same direction as those shown. Each character is represented by a six-bit code from bi-stable devices (not shown) and coupled to inputs 31 ... 36 of matrix 30; and each character has its own row of matrix 24. Assume that character 2 is to be displayed. Corresponding binary code 111000 ensures that row 37 only carries a positive voltage, derived from line 38, to the base of corresponding transistor gate 39; the gate outputs are fed to C.R.T. grid amplifier 18a. In the absence of positive voltage input to the collector of transistor 39 that gate is closed. Clock pulses from generator 11 progressively switch over the bi-stable units of counters 12 and 13; as the blanked and stepped 5x7 raster is being formed by generators 16, 19, matrices 21, 22 and 23 feed into the columns of matrix 24. The columns of matrix 23, proceeding from left to right, correspond to the successive points of the 5x7 raster and transistor gate 39 opens for unit pulse intervals according to the diode column/row connections depicted for numeral 2, thus producing the display according to Fig. 8. Counter 14 is provided to shift the raster bodily and progressively to the right to enable writing of a line of characters; and counter 15 similarly steps the display downwards line by line. Matrix 24 may be a plug-in sub-assembly to enable character display in other languages or display of, e.g., weather symbols. It is stated that the apparatus is specially suitable for airborne displays.