GB455137A - Improvements in and relating to electron discharge devices - Google Patents

Abstract

455,137. Thermionic valves and valve circuits. SCHWERIN, P., 47, West Pierrepont Avenue, Rutherford, New Jersey, U.S.A., and ELECTRONIC DEVICES, Ltd., 12, Norfolk Street, Strand, and ATKINS, H. C., 207, Princes Gardens, Acton, both in London. Jan. 14, 1935, Nos. 1276 and 7461. [Classes 39 (i) and 40 (v)] The thermionic emission from a cathode b, Fig. 1, is controlled by a second emitter a, which acts only on the first cathode, this acting as an anode to the second emitter ; this control effect is variable by altering the potential difference between the two emitters, by deflection of electrons between the two emitters or by varying the heating of the second emitter. An input grid f may be placed between the two emitters if the tube is to act as an amplifier, and a negatively-biassed grid may be used between the emitter b and the output anode c ; electrostatic or electromagnetic means may be used to deflect the electron flow from the emitter a. A single emitter a may be used to control the output of two emitters b ; indirectly heated cathodes may be used and the electrodes a, b, c, f may be concentrically arranged, the cathode b being in the form of a coil. In a further form the control electrode k, Fig. 4, is of split cylinder form and the anode c is curved. In order that the anode shall have no effect on the emitter a, a screen p, Fig. 7, is placed around the latter and the anode c is arranged out of line of the two emitters ; the screen may be an angular plate and in one form two control emitters a, Fig. 14, have screens s<2> separating them from the anode c. In cathode-ray tube constructions, the biassed screens q, q<1>, Fig. 9, may concentrate the control electron flow on to the emitter b, the screens also preventing the anode c affecting the emitter a. The emitter a, Fig. 10, may be enclosed in a Wehnelt cylinder k and be associated with accelerating electrodes l, m, n, electrostatic or electromagnetic deflecting means o and an inclined cathode b which may be of varying width ; by deflection of the beam from the emitter a a variable control is obtained. In a further form, the emitter a, Fig. 11, with control grid is separated from an accelerating anode c by the screen s ; all these electrodes may be enclosed in a cylindrical or slightly conical, biassed wall c2, a fluorescent screen t receiving the beam. The screen s may be curved. With a vacuum tube on rise of the potential difference between the two emitters, the main anode current falls until a point is reached when secondary emission is obtained from the emitter b ; the inter-emitter current is controllable. With a gas-filled envelope full grid control is retained, ionization being limited to the anode space and not between the emitters. To bias the electrodes from a single source 5, Fig. 15, the two emitters are connected by a resistance l and to one side of the battery through the resistance 2 and condenser 3 ; or a battery may be directly connected across the two emitters and be back coupled to the output coil. For use as an oscillator amplifier, the grid f, Fig. 17, is connected to a coil variably coupled with an oscillatory circuit 10, which is connected by resistance 11 and shunt condenser 12 to the second main emitter b. In another arrangement graded resistances are used to give the desired biasses.