Amber coloured signal bulbs have become very popular due to styling aspects during the recent years. In the beginning these bulbs were made out of coloured glass, which was later on eliminated for environmental reasons. Today most of the amber bulbs are coated with an absorbing filter on lacquer basis. However there are limitations regarding colour stability under certain environmental conditions like temperature and humidity with this kind of coating. On the other hand the yellowish appearance in the luminaire in the non-operating condition is not liked very much due to styling aspects. Interference coatings can address both concerns. While being hard coatings, and therefore highly resistant against all adverse conditions, interference coated bulbs also have a more neutral appearance when switched off. Moreover, with such superior characteristics, other signalling bulb colours like red, which seemed to be impossible so far, are becoming feasible. For the covering abstract see ITRD E123380.
Samenvatting