GB457371A - Improvements in and relating to electric discharge lamps - Google Patents

Abstract

457,371. Discharge lamps. BRITISH THOMSON - HOUSTON CO., Ltd., Crown House, Aldwych, London. April 22, 1936, No. 11498. Convention date, April 23, 1935. [Class 39 (i)] A filling giving polychromatic light consists of the vapour of sodium with sufficient of one or more elements of the group containing mercury and cadmium to produce radiant energy equal to at least 15 per cent of that of the sodium. Examples are (a) 2-15 per cent of sodium, 20-85 per cent of cadmium, and 12-78 per cent of mercury, (b) 4-10 per cent of sodium, 30- 65 per cent of cadmium and 30-65 per cent of mercury, and (c) 10-30 per cent of sodium and 70-90 per cent of cadmium or mercury. An alloy or mixture of the metals may be deposited on the envelope. Neon at a pressure of 1À5-5 mms. may be present. A thermionic electrode 2 and a cylindrical electrode 4 are mounted on a pinch, and similar electrodes 3, 5 are mounted from the pinch on long rods 13, 14 coated with refractory gas-resisting compound, and on rods 16, 17 with a cross member 15 engaging with a reduced part of the envelope. The lamp is enclosed in an evacuated double-walled outer envelope 18. Specification 159,170, [Class 39 (i)], is referred to.