GB397688A - Television method - Google Patents

Abstract

397,688. Television. ARDENNE, M. VON, 19, Jungfernstieg, Lichterfelde-Ost, Berlin. Oct. 5, 1932, No. 27599. Convention date, Oct. 6, 1931. [Classes 40 (iii) and 40 (v).] Relates to the method of television in which the scanning ray is of constant intensity but scans with a variable speed, and consists in preventing frequencies lower than the frequency at which the picture is completely scanned from modulating the potentials deflecting the scanning ray. This results in the time of scanning a complete picture remaining constant. Saw-toothed wave-form oscillations, developed by condensers 26, 27, Fig. 2, charged by current passing through the valves 15, 16 and discharged by a tube 24 and a commutator 41 respectively are applied to the deflecting plates 2, 3, of a cathode ray tube 1, producing an oscillation of the cathode ray on a fluorescent screen 7. The resulting light spot scans a film 11, the current from the photo-electric cell 12 after amplification passing through a filter- 14, which removes the low-frequency components, and being applied to the grids of valves 15, 16 to modulate the saw-tooth waveform oscillations. Since the period of scanning a complete picture is constant, the condenser 27 may be discharged by the commutator 41 driven bv the mechanism for moving the film 11. If the cut-off of the filter 14 is not sharp, the signals are applied to the grid of a rectifying valve 17, Fig. 3, whose output includes a resistance-capacity network 18 which is of high impedance for low frequencies and of low impedance for high frequencies so that the rectified low frequencies bias the modulating valve 16 to compensate for the low frequencies applied to its grid over the condenser 37.