GB394597A - Improvements in or relating to television and like systems - Google Patents

Abstract

394,597. Television. MARCONI'S WIRELESS TELEGRAPH CO., Ltd., Marconi House, Strand, London.-(Assignees of Ballard, R. C. ; 606, West Maple Avenue, Merchantville, New Jersey, U.S.A.) Dec. 30, 1932, No. 36906. Convention date, Jan. 6. [Classes 40 (iii) and 40 (v).] - The frequency deflecting a cathode ray 16 in one direction is maintained at a definite multiple or submultiple of the frequency deflecting the ray in the co-ordinate direction. A valve 32 generates oscillations at 4320 cycles, which are applied to the grid of a valve 34. When the potential on the grid is sufficient to cause anode current, a sharp impulse occurs in the anode circuit owing to positivereaction between an anode coil 38 and a grid coil 36. During the impulse a negative charge accumulates on a grid condenser 40 and prevents further operation of the valve until the charge has leaked away sufficiently through a resistance 42 in time for the next cycle of the oscillator 32. The anode circuit is coupled by a coil 58 to a valve 57 with a grid leak and condenser so designed that the valve responds only to every sixth impulse. Further frequency division occurs in valves 64, 68, resulting in impulses at 24 cycles. The impulses at 4320 cycles and 24 cycles are applied through potentiometers 82, 70 respectively to amplifying-valves 84, 76 which control, through a common potentiometer 78, generators 12, 18 of saw-tooth oscillations. Potentiometer 82 is so adjusted that the impulses at 4320 cycles drive the generator 12, but are of insufficient amplitude to drive the generator 18.