Patent GB-223293-A (GB)
Title: Improvements relating to vacuum electric tubes
IPC: H01J19/42
Filed: 1923-07-16
Abstract: 223,293. Robinson, E. Y. July 16, 1923. Vacuum tubes.-Electrodes of elongated form and coaxially disposed are so mounted and registered in a rigid frame comprising end members and two or more parallel side members that the axes of the electrodes are all parallel with the side members and the electrodes are constrained against any movement which could result in a variation in the gap between the electrodes. The arrangement is particularly applicable to valves in which the gap is short. The frame may consist wholly of insulating material such as glass, but is preferably partly of metal and partly of insulating material. In the arrangement shown in Fig. 1 the frame consists of parallel side members 5 of glass or steatite connected at the lower ends by nickel clamps 14 fitted around a re-entrant tube, and at the upper ends by nickel members 6 carrying the tensioning spring 12 of the filaments 2. The end and side members are secured together by binding-wire. The filaments are mounted at the lower ends on supports 20, 21 fitting on the members 5 and spaced by washers 23 and enlargements 24, and at the other ends are registered in a perforated cross-piece 27 of channel section, and are connected with a cross-piece 25 supported by the spring 12. A short-circuiting member 28 maintains the ends of the filaments cool. The anode 3 consists of two plates fitted together to form cylindrical tunnels for the filaments, and is registered and supported by means of perforated cross-members 32 fitting around the anode and side members. The upper cross-member is of channel section and is welded to the anode. The other cross-members 32 mav be flexible to allow expansion, and the anode may slide in the crossmembers, which, in turn, may slide on the side members. Binding-wire 36 may be used for securing the members 32 to the side members 5. In one modifination the frame is entirely of nickel wire, the side members being surrounded by glass or steatite tubes. In another modification the cathode consists of a tube heated bv an internal filament and is formed of nickel or molvbdenum coated with platinum, of molybdenum coated with nickel or platinum, or one of the metals alone, or of quartz with a platinum surface, with or without a coating of oxides of barium and strontium as described in Specification 221,851. Two such tubes and filaments are supported on cross-pieces in a manner similar to that shown in Fig. 1. In the arrangement shown in Fig. 7 the side members consist of nickel or steel tubes 65 screwed or clamped on glass or steatite rods 66 which may have petticoats or corrugations. The anode 23 is connected electrically with the tubes 65 by cross-pieces 71. The filament support consists of four molybdenum rods 73 connected in pairs by cross-members 74 and mounted on the frame bv cross-members 75, 78. The upper ends of the filaments are registered by hooks on a plate 87 of H-shape, and are connected with a short-circuiting piece 30 supported by springs 90, and the lower ends are secured to thick nickel wires 81 passing through insulating bushes 82 clamped in end pieces 69. The wires 81 are registered by cross-pieces 85 and are secured within the bushes by welded nickel members 84. The filaments are registered at intermediate points by hooked wires 93 pinched into glass beads 94. The electrode structure may be mounted on resilient rings 99 engaging with the ends of the container. In the arrangement shown in Fig. 15 the anode consists of plates 105 bent to form a flattened tube with flanges 107, and the grid comprises two wire helices 109 lashed to supporting-plates 111 the ends of which form sockets for the ends of the helices and are slotted to engage with cross-pieces on the frame. The filaments 2 are mounted inside the helices. The supports 111 act as a shield to confine the discharge to the curved portions of the anode, and additional shielding plates 119 may be provided. In the arrangement shown in Fig. 23 the support 129 for a flattened tubular anode 122, and the grid support 125 form the side members of the frame, the end members consisting of the pinch 131 and a vitreous head 130. A helical grid is lashed to a folded strip embracing the support 125. The filament is registered by a spring as described in Specification 222,176. In a modification a helical filament is registered as described in Specification 220.747 and the electrode supports are fused to two vitreous cross-members. In a modification of the arrangement shown in Fig. 7 the frame consists of four parallel glass or steatite rods with cross-shaped end members, and the anode is in two parts connected in parallel. Intermediate registering plates for the filaments pass through slots in the anode. Specifications 195,691, 209,505, 228,638, 231,225, and 237,980 also are referred to.