ELECTRIC LAMP WITH AN OPTICAL INTERFERENCE FILM

摘要

An electric lamp has an outer lamp envelope (1) enclosing a light-transmitting inner lamp vessel (2) in a gastight manner. A light source (3) is arranged in the inner lamp vessel. An optical interference film (4) is provided on at least part of an inner surface of the outer lamp envelope (1) or on at least part of an outer surface of the inner lamp vessel (2). The optical interference film (4) comprises a plurality of alternating high and low refractive index layers, the material of the high refractive index layer comprising substantially zirconium oxide. Preferably, the ratio of the volume Vilv of the inner lamp vessel (2) to the volume Vole outer lamp envelope (1) is: Vilv / Vole <= 0.5, preferably <= 0.25.