Patent GB-349608-A (GB)
Title: Improvements in electron discharge tubes
IPC: H01J19/34
Filed: 1930-02-28
Abstract: 349,608. Thermionic valves. WESTINGHOUSE ELECTRIC & MANUFACTURING CO., East Pittsburg, U.S.A.- (Assignees of Mouromtseff, I. E.; 1312, Elm Street, Wilkinsburg, Pennsylvania, U.S.A.) Feb. 28, 1930, No. 6715. Convention date, March 6, 1929. [Class 39 (i).] The grid electrode of an electron discharge tube consists of a tube through which a cooling medium can be passed, and a series of separately formed discs or projections mounted on the tube. The cathode filaments are located between the projections or pass through apertures in the discs. Means are provided permitting expansion of the grid tube, and screening members are provided between the cathode and anode. Fig. 1 shows an electron discharge tube comprising an anode 1 and a metal tube 5 closed at its upper end and forming a part of the grid. The tube 5 can be cooled by water which escapes through a pipe 6. Metal discs 7 spaced apart by washers are mounted on the grid tube and held in position by collars 9 secured to the grid tube by set-screws. The cathode filaments 11 pass through holes in the discs and are supported at their upper ends by rods 11a secured to a metal ring 12 carried by a quartz rod 13 fixed to the tube 5. The lower ends of the filaments are attached to rods 11b extending from rings 16 which are supported by terminal rods T. Figs. 5 and 6 show modifications of the discs 7, and Fig. 7 shows in plan a grid consisting of ribs 19 extending from the grid tube, the filaments 11 being located between the ribs. The ribs may be formed of U-shaped members welded together. Each rib supports a rod 20 by which the control is chiefly exerted, the ribs 19 serving to conduct heat away from the rods. Fig. 2 shows a modified form of tube in which the grid tube 23 is provided with an expansible bellows-like portion 23a to allow for expansion. The filaments 27 are supported by rods 27a and 27b carried by rings 28, 28a, and screening rods 29 are secured to the lower ends of the filaments by metal sleeves 29a. The upper ends of the screening rods are insulated by quartz bushes 30. Figs. 8 and 9 show the upper and lower halves of a further modification of discharge tube consisting of an outer metal tube 31 closed by glass members 32, 33. The latter supports the grid tube 36 and an inner tube 43 for the discharge of the cooling medium. The tube 36 may be provided with discs 44 or with any of the previously described forms of grid structures. To steady the upper end of the grid and to allow for expansion, a quartz rod 48 secured to the grid tube extends into a hole in a metal rod 51 slidably supported at the top. A metal cylinder 49 forms an electrostatic shield for the quartz rod 48 and prevents the deposition of conducting deposits thereon. The upper end of each filament is attached to a rod 56 which extends through a member 57 bolted to a ring 55. A spring 58 is mounted on the rod 56 to keep the filament taut. The lower end of each filament is attached to a rod 60 bolted to a metal ring 61 which is so supported that it holds the filaments taut. The supporting means for the ring 61 comprises four rods 62 attached to a second ring 64 carrying rods 66 which slide in holes in a ring 67 clamped to the grid tube. Between the ring 64 and a collar 70 on the grid tube is a spring 69 which keeps the filaments taut. Flexible conductors 85 connect the upper ends of the filaments to terminals 72. Metal shields 74 protect the seals between the tube 31 and its glass ends. The anode cooling device consists of a tube 75 leading at each end into an annular member 76 to which it is attached by a flexible ring 77. The member 76 makes a liquid-tight joint with the anode tube 31 by means of a gasket 78 which is forced into the threaded portion of the tube 31 by means of a ring 79. The latter is pressed against the gasket by a system of levers 80. Specifications 1694/15, 6486/15, 183,896, 219,019, [all in Class 39 (i), Electric lamps, Arc &c.], and 350,158 are referred to.