Method of manufacturing a lamp

Abstract

A metal halide discharge lamp is manufactured on a horizontal glass blowing lathe which is indexed by a turntable through angularly spaced work stations. Initially, a length of quartz tubing is formed into a lamp body having an enlarged bulbous midportion defining an arc chamber with tubular necks projecting in opposite directions. Thereafter, a cathode is inserted into one neck, metal halide pellets and a globule of mercury are inserted into the arc chamber, an anode is inserted into the other neck, and hermetic seals are made between the necks and the electrodes. All of the insertions are carried out by moving the various components through the tailstock of the lathe and into the lamp body through one of the necks, the cathode being moved tip-last through the one neck, across the arc chamber and into the other neck. A rotary seal attached to the headstock allows an inert dry gas to be flushed through the lamp body during the assembly steps for the purpose of drying the quartz and the electrodes and to prevent the halide pellets from being exposed to water vapor. Precision in determining the interelectrode gap is achieved by maintaining the initial seizure of the quartz tubing in the headstock of the lathe and referencing bulb formation and electrode insertion to the circular path described by the headstock.