GB961245A - Improvements in or relating to the introduction of vapour fillings into sealed enclosures - Google Patents

Abstract

961,245. Introducing gas and vapour fillings into electric lamp bulbs. GENERAL ELECTRIC CO. Ltd. May 27, 1963 [June 5, 1962], No. 21712/62. Heading H1F. In a method of introducing the vapour into the enclosures of a device which is to contain gas and vapour and to be sealed, the filling gas is fed unidirectionally along a path which passes over a quantity of a substance capable of producing the vapour on heating and then through the enclosure, the substance being at first maintained at a temperature such that little or no vapour is contained in the gas which is then used for flushing impurities out of the enclosure and is subsequently heated so that a considerable quantity of vapour passes into the enclosure with the gas stream and the enclosure is sealed off whilst it contains a filling of gas and vapour. Apparatus for carrying out the method for use in making electric incandescent lamps containing a filling of argon and iodine vapour consists of a source 1 of argon leading through a control valve 2, a gauge 3 and a drier 4 to a closed vessel 5 containing iodine crystals I. A pipe 12 surrounded by a heating coil 18 passes from the vessel 5 to a compression head 6, a narrow capillary tube 11 of platinum extending from the pipe 12 through the exhaust tube 7 of a lamp 8, the tube 7 being held in a rubber gland 9 in the head 6. A tube from the head 6 passes to atmosphere through an iodine trap 12<SP>1</SP>. The vessel 5 is surrounded by an outer jacket through which hot or cold liquid can be passed from sources 15, 16 by means of a control valve 17. Flushing of the lamp is effected by the flow of argon while the vessel 5 is maintained at a low temperature and filling is effected by raising the temperature of the vessel 5 so that iodine vapour is added to the argon, the vessel 5 being cooled again after the exhaust tube 7 is sealed off. If desired, the supply of iodine to the vessel 5 may be maintained by passing the argon through a reservoir containing iodine crystals and maintained at a temperature sufficient to produce iodine vapour, which condenses in the vessel 5 during the periods when this is cooled.