Electric lamp having an outwardly extending protrusion

摘要

The electric lamp according to the invention has a mainly tubular glass lamp vessel (1) coated with an interference filter (5) of alternating layers of SiO2 and of a material having a comparatively high refractive index. The lamp vessel 1 has portions at the area of and near its seals (6,7) having a form deviating from the tubular form and is in situ free from the material having a high refractive index of the interference filter (5). As a result, the lamp vessel (1) has a comparatively high resistance to pressure.