GB444151A - Improvements in or relating to television transmitters - Google Patents

Abstract

444,151. Television transmitters; discharge apparatus. TELEFUNKEN GES. FUR DRAHTLOSE TELEGRAPHIE, 12, Hallesches Ufer, Berlin. July 15, 1935, No. 20197. Convention date, July 14, 1934. [Classes 39 (i) and 40 (iii)] In a television transmitter of the kind in which an image is projected upon a mosaic screen or equivalent and scanning is effected by means of a cathode ray, direct impingement of the cathode ray upon the photo-active surface is obviated by forming the image, preferably portion by portion, upon the photo-cathode, from the parts of which a varying discharge of electrons is emitted and directed by means of electrostatic lenses upon a mosaic electrode so as to produce an enlarged electron image which is scanned by the cathode ray. In the arrangement shown, a mask D, used either alone when, e.g. a kinematograph film is being transmitted or in combination with a mirror wheel in the case of an actual scene, is employed to project the image line by line upon the photo-cathode 1, from which the photo-emission is directed by biassed electrodes 4, 5, 6 upon a mosaic electrode 7 comprising a line of separate insulated electrodes 8. The latter acquire charges proportional to the varying intensities of light incident upon the elemental areas of the photo-cathode 1, and form with a common positive electrode 9 a series of small-capacity condensers that are discharged by the cathode ray 10 by secondary emission to pass picture signals to the first valve 16 of an amplifier. Preferably, the ray 10 impinges on separate electrodes 12 connected to the electrodes 8, and additional electrodes 13, 14 are provided respectively to collect secondary emission from the electrodes 12 and to suppress emission from the electrodes 8. The electrodes 8 may, however, be scanned directly by projecting the cathode ray on the same side thereof as the cathode 1. The object may be imaged in successive small areas instead of line by line, in which case the electrodes 8 will have a corresponding area arrangement and the common electrode 9 will be replaced by a fine network, through which the scanning ray 10 will penetrate.