GB943740A - Improvements in or relating to low pressure electric discharge lamps - Google Patents

Abstract

943,740. Discharge lamps. CLAUDGEN Ltd. July 8, 1960 [July 9, 1959], No. 23626/59. Heading H1D. A low-pressure discharge lamp, particularly a fluorescent lamp, having a filling of rare gas with or without a metal vapour has at least one electrode in the form of a coiled metal filament coated with electron emissive material wherein the filament 6 is of bowed or V-shape supported at a point 8 between its ends by a support member 7 consisting of a length of fine refractory metal wire insulated from the supply conductors 10. The support wire 7 can act as a starting electrode due to the deposition thereon of emissive material from the adjacent electrode. The filament support point can be at the centre of the filament and the filament can be of V-shape of angle not greater than 90 degrees. The filament can comprise a single length of coiled tungsten wire and can extend through a loop or over a hook formed in the support wire 7. The sections of the filament lying on opposite sides of the support point 8 can be formed of separate lengths of coiled tungsten wire. The support wire 7 can be formed of molybdenum and have a diameter of less than 0.3 mm., preferably of 0.2 mm., and can extend beyond the support point 8 in the direction of the other electrode. The lamp can have a filling of mercury vapour with neon, or neon and argon at a pressure of about 5 to 6 mms. of mercury, and can include behind each electrode a mercury reservoir formed by a partition 13 extending across the envelope and provided with one or more nickel eyelet orifices 14, 15, as described in Specification 767,395, through which mercury vapour can distil.