GB403836A - Improvements in and relating to electric lamps - Google Patents

Abstract

403,836. Electric lamps. BRITISH THOMSON - HOUSTON CO., Ltd., Crown House, Aldwych, London.-(Assignees of Fonda, G. R. ; 1028, Parkwood Boulevard, Schenectady, New York, U.S.A.) March 1, 1933, No. 6285. Convention date, March 1, 1932. [Class 39 (ii).] An electric incandescent lamp is combined with a glow discharge lamp by mounting within a sealed transparent or translucent envelope 1 containing filaments 4, 5 a second transparent or translucent envelope 3 containing a vaporizable material and electrodes 8, 9 between which the gaseous discharge takes place. Conductors 7, 10, 11 connect the filaments 4, 5 in series with heater filaments 8<1>, 9<1> within the shells of the electrodes 8, 9, the leading-in conductors 6, 12 being soaled within the pinch 2. The electrode shells may consist of nickel, iron, or an alloy of these metals, and may be coated with barium oxide, strontium oxide or the like. Alternatively the shells may be omitted, so that the heaters function as electrodes. The outer envelope may bo evacuated, but preferably contains an inert gas such as argon or nitrogen, or a mixture of such gases at a pressure of above one-fifth of an atmosphere, or a mixture of a fixed gas and mercury vapour provided by a supply 13 of mercury. The inner envelope 3 preferably contains argon, or a like gas such as neon or helium, in addition to a charge 14 of vaporizable material such as sodium, potassium, calcium or cadmium. The envelopes 1, 3 preferably consist of heatresisting glass such as borosilicate glass. In the operation of the lamp current first flows through the filaments 4, 5 and heater filaments 8<1>, 9<1> until the temperature is sufficient to vaporize the material 14 to initiate the luminous discharge.