Patent GB-656150-A (GB)
Title: Improvements in and relating to cathode ray tube distributors for use, for example, in multi-channel pulse signalling systems
Inventor: LEVY MAURICE MOISE
IPC: H01J31/06
Filed: 1948-03-10
Abstract: 656,150. Multiplex pulse signalling GENERAL ELECTRIC CO., Ltd. March 10, 1948, No. 7358. [Class 40 (v)] [Also in Groups XL (a) and XL (b)] In a cathode-ray distributer for use, for example, in multi-channel pulse signalling systems, the beam is deflected over a plurality of secondary emissive targets each associated with an individual controlling electrode to vary the secondary emission current to an individual collector, and the final collectors serving as output electrodes are disposed clear of the path of the primary beam or are screened therefrom. In one form, Fig. 1, with electrodes elongated perpendicular to the paper, electrons from a cathode C are concentrated into a sheet and the sheet rotates around the cathode; the beam successively strikes flat or curved secondary emissive electrodes B associated with signal modulating grids G connected to the various channels and collectors A. If the device is used in a multi-channel pulse signalling system, the output is amplitude-modulated pulses. T-shaped screens S prevent the primary beam from reaching the collectors A direct, and grids such as G1 modify the electrostatic field in the paths of the secondaries. Two diametrically opposite primary beams may be used so that two secondary emissive units are operative simultaneously if there is an even number of them or only one is operative at a given time if there is an odd number of them. The secondary emissive units may be arranged around only part of a circle and the primary beam oscillated over them. A grid G2 may have a rectangular waveform applied thereto to suppress the beam except for part or whole of the times when it is directed on the electrodes B. In a modification, Fig. 2 (not shown), the electrodes A, B are arranged alternately to form a circle and each electrode B is associated with two modulating electrodes, one on either side, and arranged outside the path of the secondaries. The modulating signals vary the proportion of secondaries collected by the electrodes A and the screens S. A may serve as output electrodes or A and S may provide outputs in push-pull or separate outputs. Some or all of the electrodes A, B, G may be deposits of graphite or metal on the envelope wall. In another embodiment, Fig. 4, using a cathoderay tube with a pencil-shaped beam which is deflected to form a cone, the beam falls alternately on the glass end wall K of the tube and on projections M of a metal or graphite screen N. Secondary electrons emitted by the glass in a 1: 1 ratio are collected by output electrodes A. Modulating electrodes are provided to vary the proportion of secondaries collected by electrodes A and N. A grid G2 may be provided as in Fig. 1. Fluorescent material may be coated on the glass envelope wall at K to render the beam track visible. Specification 619,785 is referred to. The Provisional Specification refers in addition to an arrangement similar to that of Fig. 4 but using only a single collecting electrode and an arrangement similar to that of Fig. 1 in which the electron beam is deflected through a " small angle." It also states generally that only one secondary emitting electrode may be used.