APPLICATION OF PHOTOCATALYTIC REACTIONS CAUSED BY TIO2 FILM TO IMPROVE THE MAINTENANCE FACTOR OF LIGHTING SYSTEMS

Light output of luminaires gradually decreases due to stain buildup on lamps and luminaires during operation. Roadway and especially tunnel lighting experiences a large amount of contamination due to dust, carb on particles found in vehicle engine exhausts and other airborne conta minants, which results in the rapid deterioration of the light output. Photocatalytic reactions caused by TiO2 are known to decompose such s tains. This reaction is caused by the absorption of ultraviolet light (lambda less than or equal to 400 nm, corresponding to the band gap of 3 eV) irradiated from lamps or the sun, and followed by the oxidation . Extensive field tests revealed that a fine film coating of TiO2 on l amps and luminaires can effectively decompose various organic compound s such as vehicle exhaust gases, oil, nicotine, etc. This leads to an improvement of the luminous performance of installed lighting systems and reduces the cost of maintenance by approximately one-half.