GB369558A - Improvements in or relating to luminous electric discharge tubes - Google Patents

Abstract

369,558. Discharge lamps. CLAUDE, G., 3, Avenue de l'Opera, Paris.-(Assignee of Beck, L. L. ; 27, Stoneleigh Park, Westfield, New Jersey, U.S.A.) Nov. 21, 1930, No. 35134. Convention date, Dec. 7, 1929. [Class 39 (i).] Positive-column discharge tubes are provided with a filling of a colour-producing vapour and krypton or xenon and with a cathode of a refractory metal coated with an alkali metal. A current density of À5-1 À5 amps. per sq. cm. of cross section of the gas column is used so that a tube 1 of length above one metre and of 8 mm. internal diameter can be operated at the voltage of commercial mains. The filling may be krypton at 2-30 mm., preferably 5-15 mm., together with mercury vapour producing blue light. A cathode 2 of iron, copper, or nickel is coated with potassium, lithium, sodium, or caesium and the tube walls near the cathode may be similarly coated. The alkali metal is distilled into the cathode chamber, or a pellet is vaporized by external heat or by the heat of a heavy discharge. For alternating current, the anode 3 is similarly coated or two anodes are used. Rings 20 space the electrodes 2, 3 from the walls. The Specification as open to inspection under Sect. 91 (3) (a) comprises also the use instead of krypton or xenon of other low-potential gas such as argon and refers to other alkaline cathodes. The cathode may be made by coating with a compound such as potassium nitrate or azide and heating by a heavy discharge to remove occluded gases and to form a metallic or emissive residue. This subject-matter does not appear in the Specification as accepted.