Incandescent lamp having a helical coil that comprises multiple sections of different pitches

摘要

An incandescent lamp element comprises an envelope and a filament (10) supported therein by a plurality of spaced supports. The filament comprises a helical coil of wire with sections (20, 21) having at least two different pitches. The first sections (20) have a pitch which enables the filament to be operated at a required colour temperature, and the second sections have a pitch which enables the filament to be supported by the supports.