GB538382A - Improvements in and relating to distributors or commutators for multiplex signallingsystems and electron discharge devices therefor - Google Patents

Abstract

538,382. Cathode-ray tubes. STANDARD TELEPHONES & CABLES, Ltd. Jan. 30, 1940, No. 1854. Convention date, Feb. 11, 1939. [Classes 39 (i) and 40 (v)] A distributer for a multiplex signalling system comprises a cathode-ray tube with a number of secondarily emissive targets on which the ray is directed in succession and a common collecting anode. For transmission the potentials of the several targets, and consequently the emission therefrom are controlled in accordance with the separate signals and the anode is connected to the transmission line ; for reception the input is connected to the cathode and a modulating electrode and the separate signal circuits are connected between the ' targets and the anode. Fig. 3 shows a tube in which the ray is caused by the deflecting plates 50, 51 to travel in a circular path over the targets 54, the signal potentials being applied between the targets 54 and the anode 52; the leads 58 to the conductors 54 are screened by a plate 57, coated with fluorescent material to assist in focusing the ray. The sector shaped targets may be replaced by strips extending lengthways of the tube. In a modification the targets are formed on the surface of a single plate and the signal potential are applied to grids which the ray traverses on its way to the target. Figs. 18 and 19 show a further modification in which the targets are formed by sector shaped portions to 435 of metal plate 433, separated by portions 434 coated with a non-emissive material such as graphite. Corresponding to each target is a deflecting plate 438, and modulation is effected by deflecting the ray so that it passes over a wider or narrower portion of the target. The deflector plates are surrounded by a screen 440 and separated by radial screens 444. Fig. 4 shows a construction of electron gun. The cathode 35 is enclosed in a cylindrical electrode 37 secured to an insulating member 39 carried on rods 33. The insulating member has a cylindrical portion 42 through which passes a cylindrical electrode 44 and projecting into the electrode 37 and into the deflecting plates 50, 51. The secondary elecheld in place by a flange 45. The member 42 has also a flange 43 from which are supported the deflecting plates 50, 51. The secondary electrons from the targets may impinge on other emissive electrodes, the electrons from which are collected by the anode.