GB601871A - Improvements in or relating to electric discharge tubes - Google Patents

Abstract

601,871. Metal-vapour discharge apparatus. PHILIPS LAMPS, Ltd. Oct. 9, 1945, No. 26311. Convention date, June 25, 1940. [Class 39 (i)] In discharge tubes, such as mercury vapour incandescent cathode converters, having a supply of the vapour producing substance in the foot of the tube, the supply container 13, for mercury &c. 14, surrounds two separated parts 15, 16 of the exhaust tube so as to form a trap and prevent the supply of mercury &c. from reaching the main discharge space. The adjacent ends of the two parts of the tube may be covered with gauze 17, 18. In a modification, Fig. 2 (not shown), the ends of the tube are at the same level, but the lower one is flared, and the gauze covering the end 16 may be made conical with the apex directed towards the other tube part. The converter described comprises a directly heated helical cathode 2, surrounded by a shield 8 open towards the anode and closed at the other end. This shield is connected to the cathode and carries a screening disc 9. The anode 3 is a cup drawn from sheet nickel and carbonized. The anode lead 6 is sealed through the wall of the envelope by a chromeiron plate 7. The maximum temperature of the liquid mercury is 50‹ C., corresponding to a vapour pressure of 12. 5 x 10<-3> mm. of mercury. The working temperature can be adjusted during manufacture of the tube by placing the supply vessel higher or lower,on the exhaust tube. The subject-matter of this Specification is identical with that of Specification 551,226.