Incandescent lamp

Claim 1

An efficacy improved general service incandescent lamp comprising: (a) a housing having an electrically conductive base; (b) an outer envelope attached to said housing; (c) an inner envelope having an outer surface of revolution which is substantially ellipsoidal with internally located related foci, said inner envelope being spatially supported within said outer envelope, containing a halogen gas along with a fill-gas at a pressure significantly above atmospheric, and having an IR reflective film covering the substantially ellipsoidal outer surface thereof, (d) a filament adapted to be effectively energizable for normal operating wattage rating at a reduced voltage relative to a typical household power source, said filament being spatially predetermined within said inner envelope, located longitudinally along the major axis of the inner envelope, and its lighted length fully occupying the distance between the foci of the inner envelope; whereby during the operation of said lamp said film substantially transmits visible radiation and substantially reflects toward said filament infrared radiation emitted by said filament, said film being capable of such transmission and reflection for temperatures approaching the softening point of the material of the inner envelope.