METHOD OF MANUFACTURING SELFFSTARTING TYPE SHORTTARC RARE GAS DISCHARGE LAMP

摘要

PURPOSE:To prevent adhesion of molten fuse substance to the top of electrodes, by supplying current to the fuse while evacuating the inside of lamp, thus heating the fuse to the recrystallizing temperature of fuse constituting metal, and then filling and sealing rare gas in the lamp. CONSTITUTION:After completion of sealing, bulb 14 for constituting a discharge lamp is connected via air drawing tube 15 to an air drawing circuit. While evacuating the inside of this bulb 14 to a high vacuum of, for instance, 5.0X10-5 Torr, current is supplied to fuse 19 via external lead rods 17, 18, whereby it is heated to the recrystallizing temperature of the fuse constituting metal and thus fuse 19 is molten as shown at 13. After cooling the fuse to room temperature, evacuation of air is stopped, and highly pure xenon is filled in the bulb through tube 15, until pressure of xenon reaches a predetermined level. Then, base portion 20 of tube 15 is sealed. For instance, in case that a self-starting type short-arc rare gas discharge lamp is started with an instantaneous current of 150 A which causes melting of fuse 19, fuse melting time is 0.4-4 msec, although it varies with the cross sectional area of fuse 19, and there was no adhesion of molten fuse substance.