U.S. Philips Corporation

Joannes Terheijden

Josephus J Timmermans

Peter E Van Den Eijn-Den

An electric lamp has a light source which has an envelope of doped quartz glass. The quartz glass including silicon, cerium, titanium, europium and aluminium in oxidic form. Cerium accounts for 0.1-0.2, titanium for 0.01-0.04, europium for 0.03-0.2 and aluminium for at most 0.8 at % of the cationogenous elements. The aluminium/europium atomic ratio lies in the region from 3 to 8. The doped quartz glass is at least substantially transparent to visible radiation and at least substantially impervious to UV radiation.

Electric lamp

The electric incandescent lamp has a quartz glass lamp vessel (1) or envelope (4') around the lamp vessel, which has a red coloured dope in the area at the side of the incandescent body (3). The quartz glass with red dope contains samarium.sup.II oxide, aluminium oxide and silicon dioxide, the analysis of the glass in its oxidised form being Sm.sub.2 O.sub.3 to 1 to 3% by weight, Al.sub.2 O.sub.3 up to 3% by weight, rest SiO.sub.2, the molar ratio Al/Sm being at least 2.

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Eindhoven, Netherlands

Joannes Terheijden