Discharge lamp arc tube and method of making a discharge lamp arc tube

摘要

A discharge lamp arc tube (1) disposed within an outer envelope (11) of a discharge lamp has a chemical fill comprising an inert starting gas, mercury, sodium iodide, lithium iodide and scandium iodide, and is characterised in that the chemical fill also includes thallium, preferably introduced as an amalgam with the mercury, in an amount whereby the colour coordinates (x,y) lie substantially on the black body curve of a CIE standard chromaticity diagram.