HALOGEN REGENERATIVE-CYCLE INCANDESCENT LAMP WITH MERCURIC BROMIDE FILL

REGENERATIVE-CYCLE INCANDESCENT LAMP CONTAINING HgBr2 ADDITIVE The useful life of high-efficiency type brominetungsten cycle incandescent lamps, such as those used in TVstudio and theater lighting applications, is enhanced by dosing the lamps with a carefully controlled quantity of mercuric bromide (HgBr2) which dissociates when the filament of the finished lamp is energized and provides a predetermined amount of Br2 within the envelope during lamp operation. The quantity of HgBr2 dosed into the envelope is adjusted according to the design life and initial efficiency parameters of the specific lamp type so as to provide a concentration of Br2 within the envelope which is correlated with such parameters and prevents blackening of the envelope and premature failure of the filament at the particular "lifeefficiency level" of operation for which the lamp is designed. For a 1000 watt 120 volt tubular incandescent lamp (DXW type) having a design life of 150 hours and an efficiency of 28 LPW, the HgBr2 dosage is such that it provides from about 2.5 to 6 torr of Br2 within the lamp during operation ---whereas a lamp of the same wattage and voltage rating designed to operate for 50 hours at 33 LPW (DXN type) is dosed with a slightly larger quantity of HgBr2 to provide from about 3.5 to 8.5 torr of Br2 within the operating lamp.