GB901989A - Improvements relating to electric incandescent lamps - Google Patents

Abstract

901,989. Sealing electric lamp bulbs. ASSOCIATED ELECTRICAL INDUSTRIES Ltd. May 18, 1961 [June 1, 1960], No. 19423/60. Class 39 (2). [Also in Group XXIII] In a method of filling with gas and sealing the envelope of electric lamps, a vitreous tube is inserted within the exhaust opening of the envelope, gas is passed through the tube so as to displace the air and the tube and envelope are heated and deformed so as to close both the tube and the envelope. The bulb may be of the type in which the sealed neck is shaped to constitute a projecting stem for supporting the envelope in a suitable holder. A spherical bulb 1 having an extending neck 5 is supported with the neck pointing downwards, a filament 2 supported by lead-in wires 3 separated by a bead 4 is inserted through the neck and a tube 6<SP>1</SP> is inserted in the opening to lie between the leads 3. Gas, e.g. argon, is passed in through the tube 6<SP>1</SP> and the air escapes through the annular passage between the neck 5 and tube 6<SP>1</SP>. The neck 5 is then heated in the vicinity of the tube 6<SP>1</SP> and both the neck and the tube are closed by the application of pinching jaws 8, the flow of gas being maintained during sealing. The jaws 8 are shaped to produce a stem portion of the desired shape. As applied to a lamp having an inwardly-directed stem terminating in a pinch through which the lead-in wires are sealed, the exhaust tube is formed in the stem and the filling tube inserted therein, sealing taking place as close as possible to the base of the envelope. During sealing, the envelope may be drawn slightly away from the lower ends of the exhaust and filling tubes which are suitably held.