Combined silverish and infrared coating
Publication Date: 2002-Sep-25
The IP.com Prior Art Database
COMBINED SILVERISH AND INFRARED COATING
Infrared reflective coatings are used to improve lamp efficiency by reflecting the infrared light on the lamp filament when being deposited on an elliptic bulb. On the other hand, interference coating are used for aesthetics purposes in giving neutral appearance (in the off-state) to coloured-light emitting lamps. Using these 2 coatings together leads to a high price and a complex process of deposition. The invention aims at combining both features in only one interference filter : infrared reflection and silverish (or neutral) appearance. The interference filter comprises layers composed of a first layer of silica and a second layer of a material having a relatively high refractive index, which alternate with each other. A limited number of layers is needed (less than the sum of the number of layers for infrared coating plus number of layers for silverish/color neutral coating). A light-absorbing layer can be used between the bulb and the coating for the emission of coloured light.