GB191328935A - Improvements in or relating to Electric Glow Lamps and Methods of Manufacturing same. - Google Patents

Abstract

28,935. Bastian, C. O. Dec. 15. Filaments; b u l b s ; leading-in wires; residual gases.-A tungsten filament wound into a compact spiral such as is described in Specification 21,029/13 has straight ends or attached tungsten wires sealed directly into a silica bulb, forming a lamp especially suitable for high candle-powers. The filament C may comprise two coiled portions, arranged parallel as shown, or in line in a closely - fitting tubular lamp. Coiling may be done on a mandrel, filament, or thread forming a temporary core. The bulb shown is made in two parts, flanged for fusion together after the -filament has -been mounted. Such a bulb can be cleaned and used again repeatedly, and can be heated strongly during exhaustion, which is carried to a high degree. An inert gas or vapour, pure and dry, may be admitted before sealing, to a pressure at least sufficient to prevent discharges. The tungsten leading-in wires or filament-ends c may be doubled back and twisted, and the loops so formed passed through holes in solid parts D<1> of small silica tubes D. Extensions of these tubes D (not shown) are sealed, the lamp is exhausted, and the solid parts D<1> are heated and pressed. Afterwards, the extensions are cut off, and the cupped ends may receive mercury, as shown. Specifications 19,333/08 and 3864/13 are also referred to. The Provisional Specification states that (1) mercury may be used in the lamp; (2) any metal filament may be used; (3) the filament may be wound in or on a thin silica tube in a bulb of glass or silica; (4) the filament may have supports of the same metal free from oxide, or supports of tungsten, molybdenum, nickel, or the like having coatings or sleeves of silica ; (5) two or more helical filaments connected in parallel may be placed side by side to obtain a high temperature.