GB368705A - Improvement in television scanning system - Google Patents

Abstract

368,705. Television ; photo-electric cells. COMMUNICATION PATENTS, Inc., 60, Broadway, New York, U.S.A. Nov. 29, 1930, No. 36067. Convention date, July 7. [Classes 39 (i), 40 (iii), and 40 (v).] An image I, Fig. 1, of an object 0, is projected on a photo-electric cathode 5, an anode 6 receiving the emitted electrons, and the cathode is simultaneously scanned by a light beam from a device 23. The cathode 5 and anode 6 form a photo-electric cell having a non-linear characteristic so that the change of current through the cell due to the scanning light spot depends upon the intensity of the image I. In a practical embodiment, the photo-electric cell 41, Fig. 2, has a curved translucent cathode 46 and two anodes 44, 45. The object O is projected on one side of the cathode by lenses 43, while a scanning light beam from a device 42 is projected on the other side of the cathode 46 by lenses 44a. The cathode is curved so that the intensity of the scanning light spot shall remain constant for all positions on the cathode. The scanning device 42 preferably comprises an electric arc moving over an electrode system 47 under the action of a magnetic field, and is energized from a generator 75 and cooled by a fluid stream through a jacket 54 lagged at 56. The currents through the cell 41 may be amplified by a valve with a double anode 62, 64. The input circuits include variable inductances 61, 63 while the output circuit contains a transformer 67 feeding an amplifier 70, in series with a variable inductance 71. The inductances 61, 63, 71 may produce regeneration. The output of the amplifier 70 is connected to the leads 76 to the scanning device to produce regeneration. The picture and scanning currents may be filtered at 77 and transmitted. Specifications 358,183, 358,920, 360,470, 360,850, and 360,941 are referred to.