GB398290A - Improvements in and relating to enclosed electric arc devices - Google Patents

Abstract

398,290. Discharge lamps. BRITISH THOMSON-HOUSTON CO., Ltd., Crown House, Aldwych, London, STRICKLAND, R. F., 2227, Noble Road, BLAKE, H. D., 1937, Parkway Drive, both in Cleveland Heights, and McLEAN, S., Bishop Road, R.F.D.1, South Euclid, both in Ohio, U.S.A. May 17, 1932, No. 14051. Convention date, May 19, 1931. [Class 39 (i).] In arc lamps with a starting filament across the gap between the electrodes as described in Specification 317,832, [Class 39 (i). Electric lamps, Arc &c.], auxiliary electrodes 23, 24 are arranged between the main electrodes 21, 22 and the filament 25. At starting, current is led through the electrodes 21, 22 and then through the electrodes 23, 24 to. the filament to ionize the surrounding gas, and an arc forms across the filament and transfers itself to the electrodes 23, 24 and then to the shorter gap between the electrodes 21, 22. The lamp is fed from a transformer with a drooping characteristic or through a ballast. The electrodes 23, 24 may be tungsten coils with the ends of the coiled filament 25 passed through them as described in Specification 397,887, and these electrodes may extend over the bent ends of the tungsten wires 19, 20 forming the main electrodes. The electrode leads and supports have parts 12, 16, 14 respectively of copper, tungsten and a metal such as tungsten or molybdenum. The bulb 10 is of quartz or of borosilicate glass transmitting radiations down to a wavelength of 2900 Angstroms but no very short wavelengths. The bulb 10 is filled with argon at 100-125 mm. and mercury.