GB1005127A - Incandescent lamp - Google Patents

Abstract

1,005,127. Tubular incandescent lamps. SYLVANIA ELECTRIC PRODUCTS Inc. June 13, 1963 [June 13, 1962], No. 23654/63. Heading H1F. An incandescent lamp comprises a sealed tubular light transmitting envelope having a coiled-coil filament including at least two separate portions connected together by a wire of larger diameter than that of the filament, each end of the wire fitting into the adjacent end of the seconding coil of each portion and the wire being formed between its ends into a loop fitting against the inner wall of the envelope. The end of each coil not engaging the wire loop is connected to a lead-in wire. To avoid using a wire loop in the middle of the lamp filament, the filament may be made up of two outer coils 9 and a central coil 10, wire loops 11 being fitted between the coil 10 and each coil 9. Preferably the end coils are of slightly larger diameter wire than the middle coil, the internal diameters of all the primary coils being the same. The loops 11 may extend only partially round a circle, e.g. for 300 degrees, the ends being turned in radially to engage the filament coils. For a three filament coil arrangement as shown, two similar coils may be made, the ends of which extend outwards as legs to engage the ends of the wire loop. One of these coils is then cut in half to form the end pieces 9. The cut ends are then connected to the lead-in wires 7 the ends of which are shaped to fit into the ends of the filament. The lead-in wires are connected to pieces 6 of molybdenum ribbon within the flattened ends 3 of the envelope 2. The wire loops may be molybdenum, nickel or tungsten, the latter being used when the lamp filling contains iodine.