Filament-support means for a tubular incandescent lamp

摘要

The coiled-coil filament of a tubular incandescent lamp is held in suspended longitudinally-extending position within the envelope by lead-in conductors and a single support wire that is anchored in one of the envelope seals and has a hook portion that is coupled to one of the secondary turns of the filament. The free end of the filament-support member is formed into a single loop that nestingly engages the arcuate wall of the envelope and thus holds the support member and filament in the desired position during the sealing-in operation and within the finished lamp. The unique shape of the support member simplifies its manufacture and its subsequent assembly with the coiled filament and envelope. When the coiled filament is long and very flexible, proper positioning of the filament-support assembly within the tubular envelope prior to and during the sealing-in operation is ensured by providing the wire support with a finger-like extension of such configuration that it effects a slip-fit interlock with the exhaust tube that is fused to the side wall of the envelope but prevents the extension from being embedded therein when the tube is subsequently tipped-off, thus eliminating a potential air-leakage path into the sealed lamp.