GB828604A - Improvements in or relating to low pressure electric discharge lamps - Google Patents

Abstract

828,604. Discharge lamps. GENERAL ELECTRIC CO. Ltd., BREADNER, R. L., and MILES, E. E. Oct. 15, 1957 [Oct, 15, 1956], No. 31330/56. Class 39(1). [Also in Group XXIII] A low pressure mercury vapour fluorescent discharge lamp, containing a rare gas for starting, has a discharge envelope 1 which is of oval cross-section for the major part of its length and is provided along said part with a series of corrugations 9, 10 perpendicular to the axis of the envelope, extending round at least the greater part of the circumference of the envelope, and including the regions of the circumference which have the smallest radius of curvature. The ends 2 of the envelope can be of circular, cross-section, and can be of such a large diameter that in normal operation of the lamp the temperature at said ends is maintained at a lower value than that of any part of the envelope between the lamp electrodes. Methods of forming the envelope are described and dimensions stated. As described in Specification 828,605 there can be mounted at each end of the envelope a shield so as to extend over the greater part of the envelope crosssection behind the electrodes. The shield can have heat reflecting properties and can be in the form of a polished disc of aluminium, or can be of dished shape. The electrode leads which pass through the shield can have insulating bushes. The rare gas filling for starting can be argon at a pressure of 3 mms., which can be wholly or partly replaced by one or more of xenon, krypton or neon, e.g. neon at a pressure of between 2 and 4 mms.