Patent GB-830804-A (GB)
Title: A pulse train selecting device and display apparatus embodying it
Inventor: BROWN ANDREW
IPC: G09G1/14
Filed: 1957-06-06
Abstract: 830,804. Electric selective signalling; monogrammic signs. STANDARD TELEPHONES & CABLES Ltd. June 3, 1958 [June 6, 1957], No. 17981/57. Classes 40 (1) and 118(2). [Also in Group XL (c)] A circuit for selecting any desired combination of pulses from a pulse train comprises conductors 1-35, Fig. 4, to which the pulses are applied in succession, a second set of conductors 1-9 and 0, sets of rectifiers MR each interconnecting conductors of the first set with conductors of the second to transmit pulses thereto, the pulse combination on each of the second conductors being determined by the rectifiers connected to it, and a selection switch connected to the second set of conductors to select any desired combination of pulses. The apparatus described is for displaying a selected numeral on the screen of a cathode-ray tube or on a multi-electrode cold cathode discharge tube. In the form of Fig. 1 a multivibrator MV produces on two output lines, two series of pulses phase-displaced by 180 degrees from each other. These are applied through cathode followers CF1, CF2 to a distributer DT consisting of a chain-connected array of 42 (seven rows of six) gas tubes which are fired in sequence. The pulses also pass to a ring of six gas tubes LTB which produce line time base voltages for application to the X plates of the C.R.T. to step the beam horizontally across the screen. The outputs from the seven rows of tubes in the distributer DT pass to a frame time base FTB which produces a voltage increasing in steps for application to the Y plates. This controls the vertical position of the scanning beam on the C.R.T. The characters are formed by spots in selected ones of 35 (seven rows of five) positions as shown in Fig. 3, the beam being switched on at certain points so as to build up the selected character. The extra column of tubes in the distributer and in the line time base are to provide time for fly-back. Leads from the first five tubes in each row of the distributer are taken to the input lines 1-35, Fig. 4, of the translator and the ten output lines are connected to a selector switch SU. The selected line passes a series of pulses through a cathode follower CF6 to brighten the beam at the necessary points. In the form shown, the selector switch selects four lines to produce a display of four numerals simultaneously on the. screen arranged in a horizontal line. The numerals are separated horizontally on the screen by bias voltages added to the line time base voltage in successive frames by a frame counter FC. The frame counter also controls four gates G1-G4 to allow the four selected pulse trains to pass in succession to the C.R.T. beam control. More than one switch unit may be connected to the ten output lines where there is to be more than one C.R.T. connected to the circuit, each with an independent display. Monogrammic signs.-In another embodiment the distributer DT, Fig. 10, consists of an array of 42 diode gates each having an input from one of five stages of the line time base LTB and an input from one of the seven stages of the frame time base FTB. The frame time base is stepped by signals from the sixth stage of the line time base. The C.R.T. is replaced by cold cathode discharge tube CCDT having an array of seven horizontal and five vertical electrodes 30, 31. Certain cross-over points are caused to glow to display the selected character. The horizontal electrodes 30 connected to the frame time base are primed in sequence and the vertical electrodes are primed in sequence through gates G5-G9. The gates are enabled by the selected pulse train through switch SU so that cross over points glow to display the selected character. Specification 5611/14 is referred to. .