GB381866A - Improvements in electric lamps - Google Patents

Abstract

381,866. Discharge lamps. GENERAL ELECTRIC CO., Ltd., Magnet House, Kingsway, London.-(Assignees of Patent-Treuhand Ges. fur Elektrische Gl³hlampen ; 11, Ehrenbergstrasse, Berlin.) April 15, 1932, No. 10848. Convention date, June 16, 1931. [Class 39 (i).] In an enclosed electric arc lamp of the type wherein an electron-emitting filament is connected permanently across the electrodes, and the envelope contains a gaseous filling together with a pool of vaporizable metal, the form of the envelope 1 is such that the parts of it intercepted by the long axis of the lamp are approximately twice as far from the mid-point of the path of the arc as are the parts intercepted by a line in the plane of the electrodes at right-angles to the long axis of the lamp, thereby preventing excessive vaporization of the pool of metal 14 and maintaining a substantially uniform ultra-violet radiation whatever the operating position of the lamp. Preferably the envelope is in the form of an ellipsoid, as shown. The two electrodes 7, disposed perpendicular to the long axis of the lamp, may consist of tungsten or a mixture of electron-emitting substances and tungsten, or a substance, such as tantalum carbide or tantalum nitride, which is highly resistant to heat. The electrodes are mounted on supporting-wires 6 which are fastened to rods 5 and are each provided with an annular eye 8 in which the electron-emitting filament 9 is loosely hung, so that contact resistances are set up between the annular eyes and the filament. The filament is provided with additional support by two wires 10 which are sealed into a glass bead 12 mounted between two transverse wires 11. The gas filling consists of argon, nitrogen or the like.