GB483527A - Electric incandescant lamps - Google Patents

Abstract

483,527. Electric incandescent lamps with residual gases. VEREINIGTE GLUHLAMPEN UND ELEKTRIZITATS AKT.- GES. April 10, 1937, No. 10303. Convention date, April 16, 1936. [Class 39 (ii)] In a lamp provided with a compact filament, preferably coiled coil, and a filling of a permanent gas with the addition of a substance which is vaporizable when the lamp is in use, the bulb is made of a glass the softening temperature of which is above 600‹ C. and which is so reduced in size that the pressure of the filling when the lamp is in use exceeds 10 atmospheres. In the example the bulb B made of quartz glass has a length of about 20 mm., an internal diameter of 4 mm., and an external diameter of 10mm. After evacuating the bulb it is filled with a mixture consisting of 30 per cent nitrogen and 70 per cent xenon, together with a drop of mercury, the bulb being sealed when the pressure of the filling gas amounts to 1200 mm. of mercury. In use, the internal temperature of the bulb B amounts to about 700‹ C. which corresponds to a pressure of about 50 atmospheres, the light emission amounting to more than 22 lumens per watt for a life of 1000 hours. The lamp bulb B is preferably enclosed within an outer bulb F which may be evacuated. The current supply wires C, which may serve also as supporting-wires for the lamp B, may be made of nickel, with parts H made of tungsten where they are fused into the quartz bulb with the aid of an intermediate glass having a silicic acid content of more than 85 per cent. Vaporizable substances such as indium, cadmium, mercury iodide, or metalloids, such as iodine may be used as alternatives to mercury.