GB441985A - Improvements in and relating to electric discharge lamps - Google Patents

Abstract

441,985. Discharge lamps. BRITISH THOMSON - HOUSTON CO., Ltd., Crown House, Aldwych, London. Aug. 10, 1935, No. 22614. Convention date, Aug. 10, 1934. [Class 39 (i)] A lamp unit comprises a plurality of lamps or portions of a lamp arranged in close proximity to each other and to electrical heating means adapted to heat them to a temperature sufficient to maintain an atmosphere of vapour with a low glow discharge current and arranged outside the space between the lamps or portions. In one form, Fig. 2, two diametrically opposed lamps 10 are arranged alternately with two tungsten filaments 11 which are supported by braces 31, 32 from members 25 which are joined by a yoke 35 and supported from standards 17 of channel section by insulative braces 33. The standards 17 carry springs 22 the ends 23 of which engage annular ridges on metal end-caps 18 of the lamps 10. The lower caps 18 engage contacts in recesses of an insulating bar 20. A glass cup 14, sealed to an outer evacuated envelope, carries extensions 15 to which are sealed metal thimbles connected to the appropriately bent ends of the standards 17. The heaters of the electrodes 40 are joined by a lead 41 surrounded by a sheath 47 which carries a capsule 50 containing sodium or other metal. The capsule may be surrounded by a metal band 51 and after heating in a highfrequency field bursts and releases the metal. The filaments 11 are connected in series with the lamps 10 and may emit light. One lamp may have a sodium filling and another mercury or mercury and sodium, or one sodium and mercury and the other cadmium, sodium and mercury. Neon or argon at low pressure may be added. In a modification, the members 25 are dispensed with and the lamps, which have glass ends through which leads are sealed, and the filaments are supported from the standards 17. In another modification, Fig. 7, a U-shaped lamp 10b is mounted on glass collars 20a sealed to metal members 70 crimped to the thimbles 16 at 71. The filaments 11 are supported from a wire 25b wrapped round the lamp on both sides of the pip 74 and from supports 24b. In another modification the U-shaped lamp is supported on an inverted glass cup which is sealed to the lamp and to the outer bulb.