Improvements in or relating to thermionic electrodes and electric discharge lamps

摘要

835,343. Cathode constructions. GENERAL ELECTRIC CO. Ltd. Dec. 9, 1958 [Dec. 9, 1957], No. 38259/57. Class 39(1). A thermionic electrode for a high-pressure mercury vapour lamp comprises a rod 1, Fig. 1, a tungsten coil 2, one end of which fits tightly onto one end of the rod, the other end being of larger diameter and enclosing the rod and an electron emissive pellet 3. The coil was formed by winding the wire round a cylindrical mandrel consisting of two parts of different diameters, collinear along one side and joined by a bevelled section. The coil thus formed tends to return to its position of axial symmetry, such that when it is fitted over the rod and the pellet is inserted a force is applied to the pellet such as to press it against the rod. The pellet is locked in place by turning the last turn of the coil 4. Specification 594,059 is referred to.