GB461315A - Improvements in or relating to electric incandescent lamps - Google Patents

Abstract

461,315. Electric incandescent lamps. STRATEG STRAHLUNGSTECHNIK GES. Aug. 6, 1935, No. 22245. Convention date, Aug. 6, 1934. [Class 39 (ii)] In order to reduce the heat conduction and convection losses to a value not greater than 40 per cent of the total watt consumption, a gas-filled electric incandescent lamp with a filament of tungsten or other refractory metal is provided with a high-pressure gas filling consisting wholly or mainly of krypton or xenon or a mixture of those gases, a bulb volume of not more than 2À5 cubic centimetres per millimetre length of filament, and a concentrated filament giving a light yield which, for the voltage range 200-250 is at least 0À5 Heffner lumens per watt per millimetre length of filament, and for the voltage range 100-150 is at least 0À8 Heffner lumens per watt per millimetre length of filament, assuming a mean burning life of the lamp of 1,000 hours. The filament may be a single or multiple coil, the coil or coils of which may be of round or fiat cross-section. In cases where a single filament satisfying the above requirements does not ensure the requisite life of the lamp, a multiple filament arrangement may be employed so that another filament is brought into operation when the first one burns out. The gas pressure employed may be that of 550 m.m. of mercury. Preferably the filling gas contains a small quantity, for example 10 per cent, of a gas such as nitrogen, to prevent short circuiting. Reference has been directed by the Comptroller to Specification 420,575.