GB425103A - Improvements in or relating to electric discharge tubes - Google Patents

Abstract

425,103. Discharge lamps. NAAMLOOZE VENNOOTSCHAP PHILIPS' GLOEILAMPENFABRIEKEN, Emmasingel, Eindhoven, Holland. June 20, 1933, No. 17580. Convention date, June 30, 1932. [Class 39 (i)] In an electric discharge tube containing a metal vapour, more particularly vapours of difficultly vaporizable metals, e.g. sodium, and having a screen shielding a space in which condensation of the metal vapour should be avoided, the separated space communicates with the part of the tube containing the discharge path through a long narrow passage which projects into the separated space. The width of the passage must be either of the same order of magnitude as the free path of the atoms of the filling in the discharge space during the operation of the tube or smaller than this value, and the length of the passage must be at least several times, e.g. five times, the width of the passage. In a discharge tube 1, Fig. 1, provided with a pinch 2 and a screen 6 which may consist of mica or partly of metal, e.g. ferrochromium and partly of glass and which is secured by a pasty material 8 to the wall of the tube 1 below a re-entrant part 7, the long narrow passage is constituted by a tube 9, which fits closely in an aperture in the screen 6, and is secured by agglutinant to the pinch 3. In another form, Fig. 2, the screen 10 is formed of ferrochromium and covered with a glass layer 11. The screen is provided with four apertures through which pass, and are secured thereto, tubes 12, 13 forming exits for the pole wires 14. The tubes 12 closely surround the wires 14, but between the tube 13 and the corresponding wire 14 a passage exists which constitutes the long narrow passage previously referred to. The pasty material and agglutinant used are made from a mixture of talc and water glass. Specification 392,796 is referred to.