Glass composition suitable for use in a fluorescent lamp.

摘要

A new type of glass, for example, for use as TL-envelope glass, which as regards phosphor poisoning and Hg penetration has better properties than the present TL envelope glasses. Phosphor poisoning occurs in particular upon sealing of the electrodes and bending or severing and bridging, respectively, during the manufacture of SL- and PL-lamps. The composition of the glass is derived from a glass composition for use in optical glass fibres which is described in European Patent Application 83 200 958. Phosphor poisoning is controlled by restricting the mobility of sodium ions. This is achieved by choosing the quantities of the alkali metal oxides within certain limits (<<mixed alkali>> effect). Hg penetration is controlled by a large quantity of alkaline earth metal oxides in the glass. The glass according to the invention has a good light transmission. A lamp comprising a lamp envelope manufactured from a glass according to the invention only shows a small decline of the luminous efficiency during operation of the lamp.