GB1414411A - Electric lamp and base therefor - Google Patents

Abstract

1414411 Metal-vapour lamps GENERAL ELECTRIC CO 4 May 1973 [5 May 1972] 21393/73 Heading H1D [Also in Division H2] A cap for a ballasted arc discharge lamp comprises a metallic shell 26 with an end contact 25 and four diodes D1-D4 interconnected to form a rectifier bridge. The shell is screwed on to a glass jacket 2 and has an aperture in its in end in which two diodes D3, D4 are mounted aligned with the plane of the aperture and brazed or soldered to the shell. The diodes D1, D2 extend perpendicular to the plane of the aperture outside the shell where they are connected to the end contact. The diodes are glass encapsulated and capacitors C1, C2 are connected in parallel with diodes D3, D4. The diodes and capacitors are potted in filled resin 29. In an alternative embodiment (Figs. 5, not shown) the diodes are in the form of semiconductor plates stacked in pairs with conductive foil (43, 44) interposed between the diodes of each pair and connected to the arc leads (45, 46), while the end cap has a raised central portion (47) with shoulders (48, 49) which bear upon the end face of each stack. In Fig. 6 (not shown) four interconnected chip diodes are embedded in a beryllium oxide. substrate. A mercury arc quartz tube 7 and an incandescent ballast filament 17 are mounted within the nitrogen filled jacket 2 by clamping bands 15, 16 welded to a rod 12 which is clamped at 14 to a dimple 13 of the jacket. Tungsten coil electrodes 8, 9 on the tube 7 are connected to wires 5, 6 which supply the bridge rectified output, the latter electrode being connected via the ballast filament 17 and the rod 12. A starting electrode 10 is connected to the rod 12 via a resistor 11. Heat reflector discs 21 shield the base and zirconium getter rings 22 are provided. An inert gas such as argon at a pressure below 100 torr, or metal halides, e.g. sodium iodide may be added to the mercury in tube 7.