GB394883A - Improvements in or relating to television telecinematograph and like systems - Google Patents

Abstract

394,883. Television receivers. TELEFUNKEN GES. FUR DRAHTLOSE TELECRAPHIE, 12, Hallesches Ufer, Berlin. Dec. 12, 1932, No. 35208. Convention date, Dec. 12, 1931. [Class 40 (iii).] Scanning in a cathode-ray tube 1 is controlled by a circuit in which a condenser 22 discharges at the end of each scanning-line in response to the reception of a synchronizing signal and is prevented from accidental response to powerful picture signals until the end of the line is reached. Electrostatic deflecting-plates 5, 6, which move the cathode ray 4 along each scanning-line, are in parallel with the condenser 22 which is charged from the anode-voltage source 13 for the tube through a very high resistance 21 so that the circuit operates on the rectilinear part of the charging curve. The condenser is discharged by a thyratron valve 23 when made conductive by a sufficient bias applied to its grid 25 by rectified signals across a resistance 26. Additional and opposing bias, sufficient to prevent the thyratron becoming conductive, normally is applied by the anode current from a valve 28 through a resistance 27. A bias, sufficient to stop the anode current, is applied-to the grid 29 of the valve when a straight wire 18 beside the picture screen 2 is struck by the cathode ray at the end of each scanning-line. The movement of the cathode ray from line to line is controlled by a condenser (not shown), which receives a fixed increase in charge each time the condenser 22 discharges. The condenser is discharged at the end of each picture by a second thyratron or the like actuated by a special signal, which is separated from the other signals.