GB1035169A - Improvements in or relating to cold-cathode electrodes and electric discharge devices using them - Google Patents

Abstract

1,035,169. Fluorescent discharge lamps. CLAUDGEN Ltd. July 24, 1964 [July 24, 1963], No. 29300/63. Addition to 946,948. Heading H1D. The cavity electrodes of the parent Specification are constructed of two or more metal body sections, each formed with a shaped recess, which sections are assembled together so that the recesses co-operate to form the cavity. The sections may be pressed from sheet metal, iron sections being joined by spot or argon-arcwelding, and aluminium sections being joined by cold-welding, grooves being provided in the inner surface of at least one of the sections to receive support wires which are trapped between the sections during the welding. In Fig. 2 (not shown) two sections stamped from iron sheet are secured together by spot welding the flanges 16. Alternatively two sections may be formed in a single sheet of metal and then folded and welded to form the electrode. In an electrode of slightly modified shape, Figs. 3 to 5 (not shown), the cylindrical flange 11, 12 at the end of the flared part 15 is omitted. The sections may alternatively be formed by casting or moulding or by pressing and sintering a metal powder. The cavity may be either approximately spherical or ellipsoidal initially, but the spherical shape tends to an ellipsoidal equilibrium shape during operation owing to sputtering and redeposition of metal. The electrodes are used in a fluorescent lamp having a filling of neon and argon at a total pressure of 6-10 mm. Hg together with mercury vapour which may be supplied from a reservoir at one end of the envelope.