GB425685A - Method of producing relaxation oscillations, more particularly for television purposes - Google Patents

Abstract

425,685. Valve generating circuits. RADIOAKT.-GES. D. S. LOEWE, 10, Wiesenweg, Steglitz, and SCHLESINGER, K., 39, Friedrichstrasse, Friedrichshagen, both in Berlin. Sept. 20, 1933, No. 25942. Convention date, Sept. 27, 1932. [Classes 40 (iii) and 40 (v)] To prevent visible return lines on the screen of a television cathoderay tube with scanning controlled by relaxation oscillations produced by the use of a grid-controlled gas-filled discharge tube 3, the ordinary discharge of the condenser 5 is interrupted at the beginning of the slow part of the discharge curve which produces a corresponding visible path on the screen. This is done by supplying to the oscillating circuit a counter potential at least as great as the potential of the condenser at that time. The counter potential may be derived from the oscillating potential by a stepdown transformer with its primary 10 in the anode circuit of a power amplifier 7 connected to the discharge tube, and the secondary, of low high-frequency impedance, in the anode circuit of the discharge tube. A retarding network 8, 9 is connected between the anode of the amplifier and the primary of the transformer. Alternatively, the counter potential is derived from received synchronizing-signals through a phase shifter and a high pass filter, Fig. 3, (not shown).