GB485489A - Improvements in high pressure mercury vapour electric discharge lamps - Google Patents

Abstract

485,489. Discharge lamps. GENERAL ELECTRIC CO., Ltd., FRANCIS, V. J., and RYDE, J. W. Jan. 11, 1937, No. 855. [Class 39 (i)] In a high pressure mercury vapour discharge lamp having a, quartz envelope which in a vertical discharge lamp is asymmetrical about a plane midway between the running electrodes 1, 1<1>, Fig. 4, the rates between watts consumed to internal surface area of the envelope lies between 13 and 30 watts /cm<2>. The form of the envelope is such that at least one chord in a plane between the electrodes perpendicular to the line joining them is more than 7 mm. long. The refractory running electrodes are spaced apart a distance l hot greater than 2 cm., the ratio between watts consumed to being not less than 80 watts /cm. ; the voltage drop Vt during normal running across the electrodes is such that Vt /e is not less than 60 volt/cm. The lumens per watt under initial working conditions is greater than that shown in Fig. 7. The discharge may be horizontal in a lamp as shown in Fig. 5. The asymmetrical shape of the envelope ensures uniformity of temperature. Starting and running electrodes 4, 5 as described in Specification 472,658 are used. The lamp operates on mains supply wherein 6 per cent variation of voltage may occur ; its efficiency-lumens per watt-is not to decrease by more than 20 per cent during the first 100 hours of working ; it is not provided with forced cooling means, but may have a surrounding container with a chimney to promote air circulation. The inner surface of the envelope may be corrugated. The outer container may have a filling of oxygen and may have on its interior surface luminescent materials to increase the red content of the light or the red and blue as described in Specification 431,409 ; or the material may emit blue or green light. Numerical examples of lamps with vertical and horizontal discharges are given.