GB889941A - Improvements relating to the manufacture of tubular double-ended electric discharge lamps - Google Patents

Abstract

889,941. Discharge lamps. ASSOCIATED ELECTRICAL INDUSTRIES Ltd. June 6, 1958 [March 14, 1957], No. 8482/57. Drawings to Specification. Class 39(1) [Also in Group XI] A method of making a tubular doubleended discharge lamp, particularly a fluorescent lamp, consists in introducing into an outer chamber which can be connected to a multistage evacuating system or, preferably preheated, tube, providing within the chamber in demountable holders arranged adjacent the ends of the tube electrode mounts for introduction into the ends of the tube, each electrode mount having an end cap shaped to plug the end of the tube and seal thereto by contact with a deformable sealing material possessing a negligible vapour pressure, evacuating the outer chamber, introducing a gaseous atmosphere, e.g. argon, at low pressure into the chamber and a quantity of mercury into the tube, advancing the electrode mounts into the ends of the tube while maintaining the gaseous atmosphere within the chamber so that the caps are located in sealing relation to the ends of the tube and are sealed thereto, and removing the sealed envelope after the low pressure within the chamber has been raised to atmospheric pressure. The electrode mounts can comprise truncated conical caps and deformable sealing material of polytetrafluoroethylene or polymonochlorotrifluoroethylene as described in Specification 889,942. The caps can be of metal or glass and the sealing material in the form of a gasket. Alternatively the caps can be formed of the sealing material. In another arrangement sealing gaskets of silicone rubber or Neoprene can be used. When making fluorescent lamps the tube coated with a suspension of fluorescent material in a binder applied to the inner surface thereof is baked in a furnace and introduced into the chamber before cooling has occurred. Turret machines for manufacturing a plurality of lamps are described.