Low-Pressure Sodium Discharge Lamp with a Gas Filling

摘要

1,196,273. Metal-vapour lamps. PATENT-TREUHAND - GES. FUR ELEKTRISCHE GLUHLAMPEN m.b.H. 26 July, 1967 [5 Aug., 1966], No. 34342/67. Heading H1D. The starting gas in a sodium vapour lamp is Kr + A or Kr + A + Ne at a pressure of 2-6 mm. Hg, the proportion of Kr being greater than or equal to 15% by volume of the total. With a mixture of Kr+A+Ne the combined content of Kr+A may be greater than or equal to 20% by volume of the total, and is preferably greater than or equal to 35%, with the proportion of Kr greater than or equal to 30%. Preferred mixtures are 30% Kr+70% A or 40% Kr+40% A + 20% Ne. The lamp shown comprises a serpentine discharge tube 1 having oxide coated electrodes 4 and an exhaust tube 5 supported in an outer envelope 2 having an IR reflecting coating 10 of SnO 2 interrupted at 11 to eliminate electrolysis and containing getter rings 9 to maintain a vacuum of 10-3 to 10-5 torr. in the outer envelope.