GB788269A - Improvements in or relating to a method of manufacturing a partly internally silvered tubular incandescent lamp - Google Patents

Abstract

788,269. Making tubular electric incandescent lamps. PHILIPS ELECTRICAL INDUSTRIES, Ltd. Jan. 2, 1956 [Jan. 5, 1955], No. 68/56. Class 39(2) In making tubular electric incandescent lamps which are required to have a silvered reflecting coating applied over part of the inner surface of the tube, the supporting straps 20, 21 which are intended to provide intermediate supports for a longitudinally extending filament-supporting rod 11 are introduced into the tube while it is still completely cylindrical and are located in their requisite positions, and, after the silvering operation, the longitudinal support 11 with the filament 10 mounted thereon is introduced into the bulb and secured to the supporting straps 20, 21, after which the lamp is finished off in the usual manner. In the example the supporting-straps 20, 21 consist of resilient, helically wound wire, with U-shaped resilient clamps 22 and 22a respectively secured to the inner sides of some of the turns thereof, e.g. by soldering, the outer diameters of the helices being sudh that they engage the inner surface of the lamp tube 1. The open ends of the tube permit the silvering apparatus to be introduced and displaced therein, and also allow the introduction of masks for screening the part not required to be silvered. With the filament in its final position the stems 2 and 3 are sealed in the ends of the bulb in conical formations 24 and 25 respectively, the stem 2 also having an exhausting tube 28. As shown, the longitudinal support 11 comprises a glass rod carrying a plurality of wires 27 with eyes 26 which engage the filament, and wires 8, 9 sealed into its opposite ends for attachment to wires 4, 6 and 5, 7 respectively which are sealed within the stems 2 and 3, the wires 4 and 5 serving as current supply wires and 6 and 7 as stay wires. The helically coiled supporting-straps 20, 21 may consist of strip metal.