Halogen incandescent lamp with high reliability filament connection, and method of manufacture

Halogen incandescent lamp (1, 1') having

• a bulb (2, 2');
• a coiled-coil filament (13, 13'),
• said coiled-coil filament having a smaller diameter primary coiling and a secondary coiling of a diameter larger than said primary coiling,
• said coiled-coil filament being located in the bulb;
• a filament mount (8, 8') including at least two internal current supply leads (7, 7'), of tungsten wire material to facilitate operation of the lamp in a halogen cycle,
• said filament mount having end portions (15) secured to end portions of the filament;
• and
• a pinch or press seal (5) including at least two foil elements (6) sealed therein, closing off the bulb or envelope and electrically and mechanically securing the current supply leads therein,
• wherein the filament is separated into a plurality of coiled-coil portions including two coiled-coil end portions;
• said internal current supply leads each having a diameter slightly less than the inner diameter of the secondary coiling of the end portions of the filament (13, 13');
• the end portions of the internal current supply leads (7, 7') are formed with flattened, plate-like surfaces (19, 19') positioned inwardly of the terminal ends of said end portions,
• said flattened, plate-like surfaces having a lateral dimension slightly greater than the inner coil diameter of the secondary coiling of said end portions of the filament (13, 13'), and having a thickness less than the thickness of the remainder of the current supply leads;
• and
• wherein the coiled-coil end portions of the filament (13, 13') surround the end portions of the internal current supply leads from about the terminal ends thereof, extend, under tension, over said flattened, plate-like surfaces (19, 19') and over an adjacent portion of internal current supply leads (7, 7'),
• so that, upon tensioning of the filament, the inner diameter of the secondary coiling decreases, thus holding the filament against the flattened plate-like surfaces, due to a self-clamping or self-tensioning effect of the tensioned coiled-coil filament.