GB429631A - Improvements in or relating to electron discharge devices - Google Patents

Abstract

429,631. Discharge apparatus. BULL, C. S., 33, Micawber Avenue, Hillingdon, and RODDA, S., 15, Osterley Park Road, Southall, both in Middlesex. Jan. 8, 1934, No. 716. [Class 39 (i)] A device comprises a cathode, a control grid a screen grid and an anode and one or more shielding members having continuous surfaces of substantial area impermeable by electrons and extending over a considerable portion of the anode are provided and are adapted to shield from the cathode a substantial portion of the anode surface. In one form, the anode 1 constitutes the envelope of the device and surrounds a cathode 2, diamond-shaped control and screen grids 3 and 6, and arcuate strips 9, 10 of glass serving as shielding members. In a modification further shielding members in contact with the inner surface of the anode may be employed and the outer surfaces of the inner members and the inner surfaces of these outer members may be metallized, e.g. by a deposit of silver vaporized during gettering. The edges of the shields in contact with the anode may be undercut to prevent contact between the metal film and the anode. In another modification, the shielding members may consist of glass tubes arranged in line with the grid supports. The shielding members may be of conducting material and may be connected to the cathode or left insulated. Specifications 368,090, 369,052, 369,348, 370,174, 371,992, 378,994, and 389,170 are referred to.