GB207807A - Improvements in vacuum electric tube devices - Google Patents

Abstract

207,807. Westinghouse Lamp Co., (Assignees of Ulrey, C. T.). Nov. 28, 1922, [Convention date]. Vacuum tubes; R÷ntgen-ray tubes.-In a highvacuum tube such as a R÷ntgen-ray tube with an incandescent cathode, a conductor extends partly over the external surface of the spherical portion of the envelope and is permanently connected with the cathode so as to prevent electrostatic strain on the envelope due to the accumulation of electrons on the interior surface. In the R÷ntgen-ray tube shown, the exterior surface of the envelope adjacent to the cathode 11 is covered with a conducting film 13, for example, a metallic paint such as aluminium enamel, or tin or other metallic foil. The film prevents the formation of a negative charge on the interior, and concentrates the electron stream towards the anode 12, which is sealed into a long extension 9 so as to provide a long insulating path from the film; soft rays may be absorbed by the film. Specification 29143/09 is referred to. The Specification, as open to inspection under Sect. 91 (3) (a), comprises also a focussing shield of aluminium or other material transparent to R÷ntgen-rays arranged around the cathode and extending beyond the anode. In a further arrangement the wall of the envelope is thickened in the part adjacent to the cathode so as to resist electrostatic strain. This subject-matter does not appear in the Specification as accepted.