GB340049A - Improvements in or relating to electric discharge tubes - Google Patents

Abstract

340,049. Dicker, S. G. S., (Naamlooze Vennootschap Philips' Gloeilampenfabricken). Oct. 1, 1929. Low - pressure metallic-vapour apparatus; vacuum tubes.-Electric discharge tubes such as discharge tubes for the reception or amplification of electrical oscillations, rectifiers, glow-discharge tubes, and the like are provided with a foot consisting of a metal disc carrying one or more electrodes. In one form comprising a four-electrode amplifying-valve the tube 1, Figs. 1 and 2, is closed at its bottom end by the metal disc 10 which constitutes the foot of the tube and is perforated for the passage of the supply leads, the disc preferably being made of ferro-chromium, which is only slightly porous and has a coefficient of expansion corresponding to that of glass, so that its edge can be sealed to the glass wall of the tube 1. Contact-pins 13 - - 16 passing through the perforations in the metal disc are insulated from it by glass fillings, and the inner face of the disc is covered by a layer of glass 12. The pin 13 is secured to a carrier 6 which may serve as a connection to the anode 5, and glass rods 7, 8 secured to the carrier 6 carry a controlgrid 3 and an auxiliary grid 4 in addition to the incandescent cathode 2, which is attached at the top to a spring 9 secured to the glass rod 7. The top of the tube is closed by a metal cap 11 which is connected to the inner grid. The tubes may also comprise three electrode systems 27 - - 29, Fig. 5, enclosed within a glass bell 26 provided with a perforated metal plate or foot 25 sealed to its edge. The three systems have a common incandescent cathode 30 which is kept taut by a spring 33, and has its ends connected to pins 31, 32 adapted to make contact with contact springs on the bottom of a holder 31 provided with a rim 35, similar contact springs being provided to bear upon contact pins connected to the grids and anodes of the respective systems. Lugs 37 on the foot, of the tube guides 36 in the rim of the holder and provide a clamping- connection. In another form a triode valve has a metal foot comprising a metal disc with a rim which is sealed to the glass wall of the tube and is adapted to be secured to a holder by a bayonetjoint.