GB471481A - Improvements in copying telegraph systems - Google Patents

Abstract

471,481. Copying telegraphy. FARNSWORTH TELEVISION, Inc. March 2, 1936, No. 6265. Convention date, March 27, 1935. [Class 40 (iii)] Scanning a two-tone field produces impulses, which control the transmission of an interrupted signal of uniform amplitude. A tape 11, Fig. 1, carrying the matter to be transmitted is moved vertically and projected on a photo-sensitive cathode 19. An electronic image is swept horizontally by a scanning coil 31. Impulses picked up at 23 are applied to a gas-discharge tube 41, which is fed from a high audio-frequency alternator 44 and keys a wireless transmitter 50. A synchronizing signal is transmitted by applying to the tube 41 a pulse from the scanning oscillator 32. Receiver, Fig. 2. The signals are applied to a gas-discharge rectifier 55, which is biassed at 56 to pass only the signals, and is energized by an alternator 59. The output modulates a cathode-ray tube 64 in which the ray is moved in two dimensions and falls on a fluorescent screen 79 with a long time lag to produce a visual image. The signals also modulate a cathode-ray tube 66, in which the ray is moved horizontally and fall on a screen 80 with a short time lag. The light from the screen is focused on sensitive material 93<1> which is moved vertically, synchronously with the tape 11 at the transmitter, by a motor 95, which is fork-controlled or is on mains synchronized with those operating the motor 14 at the transmitter. Specifications 471,493 and 471,494 are referred to.