Abstract: An improved high efficiency general service incandescent lighting unit is disclosed. The lamp has coaxial outer and inner envelopes. The inner envelope has a low voltage filament coaxially disposed therein, a halogen gas atmosphere and a fill-gas at a high pressure. The outer envelope has a coating of a light transmissive reflective infrared film on its inner surface. Further disclosed are various control systems for reducing a typical 120 v. A.C. voltage and applying the reduced A.C. or D.C. voltage across the low voltage filament within the inner envelope.

Abstract: A high efficiency general service incandescent lamp is disclosed. The disclosed improved general service incandescent lamp has an outer and an inner envelope. The inner envelope has a relatively small housing containing a halogen gas and a relatively high pressure efficient fill-gas and in which a low voltage filament is spatially disposed therein.

Abstract: An improved incandescent lamp filament is described having an inner core of doped tungsten crystals with a surface layer of chemically vapor deposited undoped tungsten crystals. The inner core material exhibits the sag-resistant grain structure obtained with dispersion alloy products of tungsten whereas the unalloyed tungsten crystals in the surface layer are of a finer size and can further exhibit a preferred crystallographic orientation. Incandescent lamps utilizing said improved tungsten filaments exhibit increased vibration resistance and greater notch resistance when operated on direct current.

Abstract: Low wattage incandescent lamp filaments have improved squirm resistance when wound with low mandrel ratios and high pitch ratios. Squirm resistant is further enhanced when the filament is mounted under tension.