GB448041A - Improvements in and relating to electric discharge lamps - Google Patents

Abstract

448,041. Metallic-vapour apparatus. BRITISH THOMSON - HOUSTON CO., Ltd., Crown House, Aldwych, London, and SCOTT, W. J., 16, Oval Road, Rugby. Nov. 29, 1934, Nos. 34336 and 34568. [Class 39 (i)] An electric discharge device, such as a lamp, operating with a readily condensible vapour of a metal, such as sodium or potassium, has the discharge space separated from the space adjacent the seal for the leading-in wires to the electrodes by a cup-shaped member 6, Fig. 1 (34336/34), the wall of which is so close to the adjacent neck 7 of the envelope of the device that the space between them can be sealed by condensed vapour to prevent deposition of the metal in the neighbourhood of the seal; the leads 3 are insulated for the greater portion of their length by insulating tubes 4, preferably of glass, and pass through grooves or channels 5 formed between the wall of the cup and the adjacent neck of the envelope, the grooves being formed either in the wall of the cup, as shown, or in the neck, or partially in both. The leads may be diametrically opposed, as shown, or, in a modification, are all embedded in a strip of glass or other insulating material, and pass through a single groove in the cup. The cup 6 may be filled with glass wool. In a further modification, the grooved cup-shaped member 2, Fig. 4 (34568/34), is sealed at its bottom end to the end of the bulb neck. The leading-in wires 5 pass through the seal and are protected by glass tubes 4. In assembling the device the cup and tubes may be held together by a band or wire. Specification 440,999 is referred to. The Second Provisional Specification describes modifications in which the protective tubes 4 are sealed into the seal between the cup-shaped member and the envelope neck, and may project through the seal, the tubes being then made of sodiumresisting glass. It is further stated that the tubes 4, Fig. 4, may be of steatite.