GB371612A - Improvements in television - Google Patents

Abstract

371,612. Television. COMMUNICATION PATENTS, Inc., 60, Broadway, New York, U.S.A. May 1, 1931, No. 12866. Convention date, Oct. 1, 1930. [Classes 39 (i) and 40 (iii).] In a television system, a light source is adapted to analyse an object and coincidently to reconstitute an image, which may be an image of the object analysed. The object is scanned by light passing through a pinhole 4 in a screen 8 from an electric arc moving along an electrode system 6, 7. A light-sensitive cell 25, or a number of cells in parallel, receives light reflected from the object and the picture currents are amplified at 26, 27 and transmitted from an aerial 33. An aerial 34 receives picture signals which are amplified at 39 and superimposed on the scanning arc. The circuits 27, 39 contain transformers 30, 41 whose third windings are connected inversely in parallel to an oscillator 43 so that the thermionic valves 29, 40 are alternately biased to an inoperative condition. The frequency of alternation is sufficiently high to produce apparent continuity of the received image. The light source is thus alternately modulated by the incoming picture signals while the transmitting apparatus is inoperative, and of constant intensity while the receiving apparatus is inoperative. For monitoring purposes the switch 48 may connect the circuit, through a delay device 47, with the electric arc so that an image of the object being analysed is reconstituted. The screen 8 is of translucent material, such as quartz, so that an observer may see the reconstituted image and that the analysing beam projected through the pinhole 4 shall be substantially the only illuminating beam while the transmitting apparatus is modulated. The system is synchronized as described in Specifications 360,470 and 360,941.