ELECTRODE FOR HIGH-VOLTAGE DISCHARGE LAMP, ITS MANUFACTURE, MANUFACTURE DEVICE, AND HIGH-VOLTAGE DISCHARGE LAMP

摘要

PROBLEM TO BE SOLVED: To reduce chip in manufacturing and to improve plowing characteristics in lighting by constituting an electrode of a cylindrical base part called a shaft part and a tip part formed into a cone and by molding the tip part in the radial direction using a molding dice formed into a shape matching to a prescribed tip part. SOLUTION: A negative electrode 4 is composed of tungsten doped with 0.4 wt.% ThO2 . To secure the stability of the height of the arc, a cylindrical base part forming a shaft part 5 of a negative electrode 4 is gradually getting narrower into a truncated cone to be formed into a tip part 9 so that the outer casing part 11 of the cone has an aperture angleαand the discharge side is finished at the flat part 10. The tip 9 is formed by forging in the radial direction, the organization structure is extremely pulverized by the shaft part formed of a drawing organization structure. Only the flat part 10 is aftertreated by polishing in the last. The stability of the organization structure in the region of the tip part 9 subjected to high thermal load can be thus improved.