GB471330A - Improvements in or relating to electric discharge devices - Google Patents

Abstract

471,330. Discharge lamps. GENERAL ELECTRIC CO., Ltd., FRANCIS, V. J., and RYDE, J. W. March 3, 1936, No. 6427. [Class 39 (i)] A high-pressure mercuryvapour discharge lamp having high brightness and liable to instability comprises a solid body intersecting or approaching closely the straight line joining the points at which the discharge column terminates on the electrodes, whereby, when the lamp is operated with the line vertical, part of the column is so far displaced from the line that the column is rendered stable by the displacement. The envelope is of approximately spherical shape and does not restrict or stabilize the discharge column. In the form shown, a pear-shaped envelope 1 contains two electrodes 2, 3 about 9 mms. apart. A tungsten blade 4 supported on a stem from the envelope intersects the line between the electrodes at point 6. A notch 5 is provided in which the arc rests. Starting electrodes 9, 10 are provided. If the arc be long, two or more blades are provided insulated from one another. Alternatively, a block of insulating refractory material, such as thoria, may extend in the direction of the arc. Specifications 431,923, 434,919, and 470,770 are referred to. According to the Provisional Specification the refractory body may be a fluid-cooled re-entrant portion of the envelope.