GB1174745A - Improvements in Seals for Electrical Devices - Google Patents

Abstract

1,174,745. Electric incandescent lamps. BRITISH LIGHTING INDUSTRIES Ltd. 1 July, 1968, No. 31324/68. Heading H1F. [Also in Division C1] A seal for an electric device, e.g. a tungstenhalogen lamp comprises a quartz glass envelope 16 and a lead-in conductor sealed in and extending through a flattened neck 17 of the envelope, the lead-in conductor having respectively metal foil portions 19 arranged in layered array, adjacent foils of the array being separated by a glass 21 having a lower softening point than the quartz glass, the foils being hermetically sealed between the neck of the envelope and the lower softening point glass. In a preferred form the lead-in conductor comprises a pair of molybdenum foils 19 sealed into the quartz glass neck 17 with " Vycor " glass (Trade Mark) separating them to form a good seal. A loop of tungsten wire 18 connected at each end leads into the envelope and a loop of platinum coated molybdenum wire 20 leads outside the neck, each end being connected to a free end of a foil 19. In an alternative embodiment (Fig. 3, not shown) there is sealed into the neck two lead-in conductors each similar to that above. Another embodiment discloses a lead-in conductor having three foils 19<SP>111</SP> in a layer each pair of adjacent foils being separated by a layer 21 of " Vycor " glass. Three tungsten wires 18<SP>111</SP>, 22 in parallel, one wire connected to each foil, lead to the inside of the envelope and similarly three platinum coated molybdenum wires 20<SP>111</SP>, 23 to parallel lead from the foils to the outside of the neck.