GB256975A - Process of making vacuum tubes - Google Patents

Abstract

256,975. Loewe, S., Aug. 11, 1925, [Convention date]. Vacuum tubes; R÷ntgenray tubes. - In producing high vacua in vacuum tubes such as rectifiers, transmitting valves, valves with oxide or other highlyemissive cathodes and Rontgen-ray tubes by vaporizing magnesium or other substance, this substance is carried upon a support from the anode or other element of the electrode system, the substance being vaporized only after the anode &c. has been incandescent for some time and has been freed from gas and the dimensions and material of the support determining approximately the whole period of time between the commencement of incandescence of the anode &c. and the vaporization of the substance. The magnesium or other substance 6 may be carried by a metal strip 9 welded to the centre of the anode 5 of a 3-electrode tube so as to be heated by conduction and radiation of heat from the anode. The substance 6 is mounted in such a position that the electrode system screens the foot 8 and a part of the bulb to prevent the formation of a metallic deposit thereon. A metallic bridge between the electrode leads is tbus avoided whilst the clean part of the bulb allows dissipation of heat from the filament without heating the cap of the tube. The anode 5 is made incandescent by electron bombardment or eddy currents and the substance 6 may be additionally heated by eddy currents in the latter case. The Specification as open to inspection under Sect. 91 (3) (a) comprises also arrangements in which the substance 6 is heated solely by radiation, the substance 6 being on a glass or metal carrier 7 on the bulb 1 or on the foot 8 or on the electrode system. This subject-matter does not appear in the Specification as accepted.