GB374400A - Improvements in or relating to television and like systems employing cathode ray tubes - Google Patents

Abstract

374,400. Television receivers. TELEFUNKEN GES. FUR DRATHLOSE TELEGRAPHIE, 12, Hallesches Ufer, Berlin. March 2, 1932, No. 6366. Convention date, March 2, 1931. [Class 40 (iii).] Relates to a cathode ray receiver in which the cathode stream from the cathode 1, Fig 1 passes through a tubular anode 2, an aperture 5 and between the scanning plates 6 .. 9 to the screen. In a known arrangement, the received signals are applied to the condenser plate 3 so that the cathode ray only passes through the aperture 5 during the short period when the received signals are passing through zero valve. According to the invention, the pulsating potential applied to the plate 3 is of zero amplitude for periods of time in each cycle, varying in linear relation with the strength of the received signals. The required oscillating potential is obtained as in Fig. 3, where a source of constant frequency alternating potential 10 is in series with a rectifier 11, and the received signal source 12. The potential tapped off from resistance 13 to be applied to the plate 3 is of zero amplitude for half a cycle, when the potential of 12 is zero, and when the potential of 12 is a maximum no period of zero potential occurs. The oscillation generated at 10 may be a straight line wave form oscillation. At high frequencies, the capacity of the rectifier 11, e.g. a valve, is compensated by a condenser 17, Fig. 4, in a bridge having resistances 18, 19.