GB1226395A - - Google Patents

Abstract

1,226,395. Cathode-ray tube displays. TELEFUNKEN PATENTVERWERTUNGS G.m.b.H. 18 July, 1968 [18 July, 1967], No. 34180/68. Heading H4T. Linear traces drawn on the screen of a cathode-ray display tube by deflection of the beam are broken up into segments having a desired pattern (e.g. to produce dot-dash, chain-dotted lines &c.) by controlling the intensity of the beam in accordance with such pattern. The latter is determined by the markspace ratio of a pulse pattern generator, e.g. a multivibrator, the output of which, as shown, is fed to one input of an AND gate U which is opened by the output of a timing circuit for the duration of each trace which is produced by connecting the vector generator to the tube deflection means (not shown). The output of gate U then opens and closes a switch S in accordance with the mark-space ratio of the pulses and correspondingly interrupts the supply of beam intensity control information which is fed via the switch and an amplifier to the brightness control electrode of the tube. When the vector generator is of the kind that causes all lines to be drawn in a constant time interval irrespective of their lengths the brightness information is suitably modulated so that all lines are of uniform brightness. The pulse pattern generator is arranged to be started in the same phase position by the start signal which is repetitive at the display repetition frequency. Alternatively, the generator may generate the pattern constantly and the start of the vector drawing arranged to occur at a particular phase position or the constantly operating generator may be brought into a desired phase position by a trigger pulse. Different pulse generators may be provided for the different patterns required or a single-pulse generator having a switchable pattern may be employed.