GB329802A - Improvements in or relating to electron discharge devices - Google Patents

Abstract

329,802. Cleartron (1927), Ltd., and Sinclair, J. R. April 27, 1929. Vacuum tubes. -In discharge devices with three or more electrodes in a glass envelope, particularly screened grid valves, an intermediate electrode 9 such as the screening grid is provided at one or both ends with a flanged or dished metallic screen 9<a> the outermost edge of which is in the end plane, or between the end planes, of the outermost electrode 10, the screens 9<a> lying wholly within the electrode 10 with their flanges adjacent thereto to intercept the lines of force which would otherwise flow from the ends of intermediate electrodes to the electrode 10.. The screens 9<a> and electrode 10 may be flared outwardly at the ends as shown, the distance between the flares 9<b>, 10<a> decreasing outwardly. The filament and control grid are supported by wires passing through the lower screen 9<a>. An earthed sheet-metal screen may surround the electrode system. In a modification, the screens comprise flanged discs with the flanges parallel to the electrode 10.