Abstract: A method of establishing coil dimensional stability by thermally stress relieving the tungsten filament prior to mounting in a lamp. The filament is manipulated into the desired position by coiling it first around a primary mandrel, then a retractable secondary mandrel. After the secondary mandrel is removed, the filament is held in place by a pair of electrical contacts. A current is passed through the primary coil, which heats the tungsten and causes it to recrystallize. The recrystallization provides the desired dimensional stability.

Abstract: A method and apparatus for more precisely centering lamp leads (32, 34) uses a support mechanism (50) for radially aligning the leads. The support mechanism is a helical member having first and second helical portions (52, 54). The first helical portion has a diameter slightly less than the inner diameter of the lamp envelope to maintain a filament (30) on axis. The second helical portion has an outside diameter less than the outside diameter of the first helical portion for securing the support mechanism to a mounting mechanism (60). Here, the mounting mechanism is preferably defined by first and second flattened portions (62, 64) integrally formed on the lead that axially positions the support mechanism in place.

Abstract: A tungsten-halogen lamp has a light transmissive, IR coated, filament chamber enclosing a filament, the filament chamber being enclosed within an outer envelope. Fuses are connected to opposite ends of the filament to limit the magnitude and duration of an electrical arc across a break in the filament which, in combination with a fill gas pressure of no greater than 2500 Torr reduces the likelihood of containment failure.

Abstract: An incandescent lamp containing a coiled filament within a vitreous envelope wherein the filament is supported at at least one point along its coil length by a refractory metal support wire one end of which is welded to a coil and the other end secured to the envelope wall by a glass bead. The support prevents filament sag during lamp operation and is especially useful with double-ended high intensity tungsten-halogen lamps having an elliptically shaped filament chamber with an infrared reflecting and visible light transmitting optical interference coating on the chamber.

Abstract: Tungsten-halogen lamps operating at temperatures above 250.degree. C. which contain a mixture of phosphine, hydrogen, bromine and inert gas have been found to have superior life and lumen maintenance when the atomic ratio of phosphorus to bromine in the lamp is in the range of from 0.4-2.5.

Abstract: An elongated tubular lamp such as an arc lamp or tungsten halogen lamp mounted in a reflector or lamp mount by means of a long and a short mount wire is more resistant to breaking off the mount wires if the short mount wire is smaller in diameter than the long mount wire, but not smaller than the diameter of the lamp lead wire to which it is welded in combination with the lamp lead wire being molybdenum alloy having a recrystallization temperature at least about 200.degree. C. higher than molybdenum.

Abstract: Incandescent lamps having an improved light source are disclosed. The light source contains a halogen compound along with a fill-gas at a pressure above atmospheric. The light source has an oblate ellipsoidal shape so as to obtain a desired temperature gradient which reduces typically experienced "cold spots" that detrimentally contribute to the condensation of halogen compounds within the light source which would otherwise reduce the desired light output of the light source throughout life. Also disclosed is a method of manufacturing the light source.