Variable-Color Fluorescent Lamps with Both Internal and External Electrodes

Abstract

In this paper, the color control of xenon-mercury fluorescent lamps through the use of both internal (longitudinal direction) and external (radial direction) electrodes is described. The inner surface of the cylindrical lamp was fully or partially coated with a mixture of two kinds of color phosphors. One of the phosphors is excited by the resonance radiation of mercury, and the other is excited by the vacuum ultraviolet (VUV) radiation of xenon. The color of the lamp light can be changed from that of one phosphor to that of the other phosphor by varying the mixture ratio of longitudinal discharge (LD) by the internal electrodes to radial discharge (RD) by the external electrodes. The wide color range in the Commission Internationale de l'Élairage (CIE) chromaticity diagram is obtained as follows: (x,y)=(0.262,0.129)-(0.533,0.280) for a blue-red lamp, (x,y)=(0.513,0.390)-(0.285,0.625) for an orange-green lamp and (x,y)=(0.139,0.147)-(0.166,0.548) for a blue-green lamp. The luminances are about 1000 cd/m2 for these lamps.