Fluorescent lamps with very high luminous efficiency

Abstract

Some years ago a new generation of fluorescent lamps with 80 Im/W and a colour rendering index of 85 was developed, which used newly developed phosphors with narrow emission bands. Recent improvements in these phosphors have opened up new possibilities as far as lamp geometries are concerned. For example, 1200 mm 40 W lamps in 25 mm diameter with about 95 Im/W, a colour rendering index of 85 and a lumen maintenance which is better than that of 37 mm diameter 40 W lamps with halophosphate phosphors, can now be realized. The newly developed lamps therefore have 15 to 20% higher efficacies than existing standard lamps, and provide an answer to the increasing demand for energy conservation.