GB379736A - Electronic discharge tubes - Google Patents

Abstract

379,736. Electron discharge tubes. STANDARD TELEPHONES & CABLES, Ltd., Columbia House, Aldwych, London.- (Assignees of Bond, D. S. ; 51, Clark Street, Brooklyn, New York, U.S.A.) June 4, 1931, No. 16230. Convention date, Sept. 17, 1930. [Class 39 (i).] In an electron discharge tube comprising a cathode and two anodes, as in a full-wave rectifier, the cathode is in the form of a coiled or folded ribbon so disposed as to constitute a physical and/or electrostatic shield between the anodes. Fig. 1 shows one arrangement of a high vacuum full-wave rectifier tube in which the cathode is in the form of a nickel ribbon 15 coated with alkaline-earth oxides, e.g. barium or strontium oxides, wound helically around insulating sleeves 21, Fig. 3, on supporting rods 19 attached at one end to leading-in wires 17, 18 and spaced at the other end by an insulating plate 20. Annular spacers 22 between adjacent sleeves 21 prevent contact between adjacent turns of the ribbon, the ends of which are connected to wires welded one to each of the rods 19. Each anode 16 is a rectangular metal plate welded along a central ridge 25 to a leading-in wire 26, 28 anchored at its upper end to the plate 20. Magnesium ribbon 30 adapted to be vaporized to fix residual gases is carried in a dished disc 31 supported by a wire 32 from the leading-in wire 17. An easily ionizable gas or a vapour-producing substance such as a globule of mercury 33 provides the conducting filling. Fig. 5 shows, with the parts dismantled, a modification employing a similar cathode structure with a somewhat wider ribbon 15, this structure being surrounded by a heat-reflecting shield 34 of bright metal supported from the plate 20, and the anodes 35 being in the form of semi-cylinders supported from the plate 20 and from the leading-in wires 26, 28. A central rectangular opening is provided at each side of the shield 34 for the passage of the discharge and arcing between adjacent edges of the anodes is prevented by metal shields 42, 43 supported from the plate 20 and from the leading-in wires 17, 18. Each anode may be provided with a central aperture 44 for observation of the discharge. In a further modification, Fig. 7, the anodes in the form of discs 48, 49, preferably of graphite, are supported by leading-in wires 46, 47 passing through an inwardly projecting stem 45 at one end of the enclosing vessel (not shown), and the cathode in the form of a suitably coated zig-zag metallic ribbon 50, Fig. 8, is provided with leading-in wires 52, 53, 57, 58 parsing through an inwardly projecting stem 12 at the other end of the vessel. The wires 57, 58 connect the lower end of the ribbon to one terminal, the wires 52, 53 connect a metal box 51 surrounding the ribbon to a second terminal, and the upper end of the ribbon is connected by a yoke 59, wires 60, 55, 54 to the box the wire 55 being supported from the stem 45. Rectangular openings for the passage of the discharge are provided in the sides of the box 51 adjacent to the edges of the ribbon.