GB434598A - Improvements in and relating to electric discharge devices - Google Patents

Abstract

434,598. Discharge lamps. BRITISH THOMSON - HOUSTON CO., Ltd., Crown House, Aldwych, London, and SCOTT, W. J., 16, Oval Road, Hilhnorton Paddox, Rugby. March 5, 1934, No. 6967. [Class 39 (i)] A high-pressure lamp contains a mixture of mercury and another vaporizable material such as cadmium, the mercury only being entirely vaporized and the unevaporated portion of the other material acting as the cathode of the lamp. Preferably the material is contained in a pocket 3, Fig. 1, in a metallic cap 2 sealed to each end of the lamp. Cooling fins 4 may be provided on the cap. The cap itself or projections from it may act as anodes. An annular metallic ring may be sealed in the tube in front of the cathode to prevent sputtering and blackening and to act as a starting electrode or grid, Fig. 4 (not shown). In Fig. 3 a shield 6 projecting from the cap 2 protects the seal and prevents blackening. The material may also be contained in a cylinder 5, Fig. 5, and the tube drawn down and sealed to the outside, or to a flange projecting from the cylinder, Fig. 6 (not shown). In a tube surrounded by a vacuum jacket, the pockets may project through the wall of the jacket.