Low sag tungsten filament having an elongated lead interlocking grain structure and its use in lamps
AssigneeGeneral Electric Company
InventorsJohn W. Pugh, Donald L. Bly
Life of this patent
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Abstract
Improved tungsten coil filaments having good sag resistance and useful in double ended, high intensity and energy efficient tungsten halogen lamps having an IR reflecting filter on the filament chamber. These coil filaments have a microstructure which is a large, elongated and interlocking grain structure produced by a high temperature heat treatment process.
Claims64
A coiled tungsten filament having a microstructure comprising an elongated and interlocking grain structure having a grain shape parameter of at least about 10.
A coiled tungsten filament having an elongated and interlocking grain microstructure which has a grain aspect ratio of at least about 50.
An incandescent electric lamp comprising a hermetically sealed, light transmissive envelope enclosing a coiled tungsten filament within, said filament having an elongated and interlocking grain microstructure having a grain shape parameter of at least about 10.
A tungsten halogen lamp comprising a hermetically sealed, vitreous, light transmissive envelope having a filament chamber enclosing within a coiled tungsten filament and a fill comprising one or more halogens, wherein said filament has an elongated and interlocking grain microstructure having a grain shape parameter of at least about 10.
A tungsten halogen lamp comprising a hermetically sealed, vitreous, light transmissive envelope having a filament chamber enclosing within a coiled tungsten filament and a fill comprising one or more halogens, wherein said filament has an elongated and interlocking grain microstructure having a grain shape parameter of at least about 10 and wherein said filament chamber contains a thin film optical interference coating on the outside surface thereof for reflecting infrared radiation and transmitting visible light radiation emitted by said filament, and further, wherein said filament is at least about 85% recrystallized, has a grain aspect ratio of at least about 100 and a grain boundary factor no greater than about 15.
Dependencies are inferred from the claim text.