COIL-SHAPED FILAMENT AND INCANDESCENT ELECTRIC BULB

摘要

PROBLEM TO BE SOLVED: To provide a triple coil-shaped filament and an incandescent electric bulb using this coil-shaped filament in which deformation or short circuit between pitches is hard to occur even when an impact or a vibration is applied to the coil-shaped filament, and in which improvement of the shock resistance and the vibration resistance can be promoted.;SOLUTION: This is the coil-shaped filament and the incandescent electric bulb L using this filament of a formation of the coil-shaped filament in which tungsten thin wires are wound up so that inner diameters of the coils have a relationship of primary coil≤secondary coil≤third coil, while % mandrel of the primary coil is 100 to 400%, % mandrel of the secondary coil is 100 to 300%, and % mandrel of the third coil is 100% or less.;COPYRIGHT: (C)2007,JPO&INPIT