HIGH PRESSURE MERCURY LAMPS WITH A LOW COLOUR TEMPERATURE AND A HIGHER LUMINOUS EFFICACY

Since the introduction of the mercury high pressure lamp efforts have always been made to get a higher luminous efficacy and a better colour by appropriate fluorescent materials. For the lighting of interiors as well as street lighting there was a need for high pressure lamps with lower colour temperature. This can be obtained with a thicker fluorescent layer, which gives however a loss of luminous flux of 10%. By the use of cristalised yttrium-vanadium as fluorescent material a gain in luminous flux of 16% can be obtained. This new hpl-de luxe lamp with a more agreeable colour is better fitted for public lighting especially in residential areas. (TRRL)