GB280851A - Improvements in or relating to thermionic valves or electron discharge tubes - Google Patents

Abstract

280,851. Naamlooze Vennootschap Philips' Gloeilampenfabrieken. Nov. 19, 1926, [Convention date]. Vacuum tubes. - A valve has a cathode, an anode, a control grid, a screening grid of substantially the same length as the control grid, and one or more metal shields insulated from the screening grid and connected with a point of constant potential, the shields being so shaped and arranged that all the electrostatic lines of force between the control grid and anode are compelled to pass through the screening grid. As shown in Fig. 1, the metal shields 7, 8, of smaller diameter than the screening grid 5, are mounted by glass rings 11 on the control grid 4, and are connected together by a band 12, the plate 8 being connected with one of the leads for the filament 3. The lead for the anode 6 is taken through the foot 2, and the lead for the control grid through the top of the envelope. In a modification the plates are mounted on the screening grid. In another arrangement the plate 8 is mounted on one of the filament leads, and the plate 7 is mounted on a rod which supports the loop of the filament and is sealed in the top of the envelope. In the arrangement shown in Fig. 5 the plates 7, 8 are mounted by glass rings 11 in' the anode 6, and are provided with metal rings 20 projecting between the control grid 4 and screening grid 5. In a further arrangement the plates 7, 8 are joined by two or more metal bands or by a cylindrical metal screen, and the plate 8 is carried by a filament lead and by a support mounted in the foot.