GB830243A - Improvements in or relating to gas-filled electric incandescent lamps - Google Patents

Abstract

830,243. Electric incandescent lamps. EGYESULT IZZOLAMPA ES VILLAMOSSAGI R. T. April 17, 1957 [April 28, 1956], No. 12593/57. Drawings to Specification. Class 39(2) An electric lamp with a rated voltage below 40 but preferably above 10 volts, comprises a glass envelope containing a metallic, e.g. tungsten, filament and a gaseous filling of a mixture of xenon and nitrogen at a pressure between 450 and 700mm. of mercury, wherein the percentage of nitrogen in the mixture lies between the value given by the formula N 2 = (V-5)/K and 110% of this, where N, is the percentage of nitrogen, V the rated voltage of the lamp and K a numerical factor varying substantially linearly between the value 3 at a pressure of 450mm. and 4 at a pressure of 700mm., the filament and its supports being so arranged that the distance t between the points of highest potential difference on the filament or on the filament and one of its supports is not less than that given by the formula t=V.#W.#L/W.C where W is the rated energy consumption of the lamp in watts, L/W the luminous efficiency in lumen/ watt and C a numerical factor varying between 0.015 and 0.035, higher values being chosen where the liability to arc flashing is greater. In place of xenon, a mixture of xenon with other rare gases e.g. argon, krypton, wherein the proportion of xenon is at least 80% may be used. Specification 359,749 is referred to.