GB398799A - Improvements in electric discharge lamps - Google Patents

Abstract

- 398,799. Discharge lamps. BRITISH THOMSON-HOUSTON CO., Ltd., Crown House, Aldwych, London.-(Assignees of Spanner, H. J.; 117, Chausseestrasse, Berlin.) Dec. 19, 1931, No. 35192. Convention date, Dec. 20, 1930. Drawings to Specification. [Class 39 (i).] A lamp of the type described in Specification 397,162, and provided with an activated cathode having on its surface, in addition to force electron-active metals the work-function of which is less than 3 volts, substances which are poor conductors of heat and electricity as described in Specification 356,234 is dimensioned as follows:- The distance between the electrodes, measured along the centre of the tube, is approximately ten times the diameter of the tube ; the inner radius of curvature at the apex is approximately twice the diameter of the tube ; and the direct distance between the electrodes is approximately (but not less than) half the distance measured along the centre of the tube. Conveniently the tube is of parabolic shape, and is constructed of quartz or borosilicate glass Imm. thick. In addition to mercury, the tube may contain argon at a pressure of 3 mms. and may be provided with a starting strip as described in Specification 356,234. According to the Specification as open to inspection under Sect. 91 of the Acts, a lamp of the type described in Specification 356,234 and having a high-pressure metal vapour filling may be dimensioned as above. The lamp may be operated in series with an incandescent lamp, e.g. of tubular form to produce a daylight source without flicker. Iron-hydrogen resistances may be used instead of the incandescent lamp and flashed or opal glasses may correct the colour of the light. The lamp may be filled with vapours of sodium, thallium, thorium, or rubidium. The Specification as open to inspection also comprises the subject-matter of Specifications 398,815 and 398,824. This subject-matter does not appear in the Specification as accepted.