ELECTRIC LAMP COMPRISING A LIGHT ABSORBING MEDIUM

摘要

The electric lamp employs a lamp vessel (1), which is transparent to visible light and which accommodates a light source (2). The lamp vessel (1) is covered with a combination of a light-absorbing medium (6) and an optical interference film (5) employing layers of alternately a first layer of a material with a comparatively high refractive index and a second layer of silicon dioxide. A spectral transmission T of light transmitted by the light-absorbing medium (6) changes from T<=0.15 to T>=0.75 in a wavelength range having a width lambda<=50 nm. The variation in reflection R amounts to less than 10% in the wavelength range 400<=R<=690 nm, the reflection R and lies in the range 50<=R<=90%. In operation, the electric lamp emits colored light in the transmission mode and has a substantially color-neutral appearance in the off state.