Variable Color Discharge Lamps with Internal and External Electrodes.

Abstract

This paper describes a method for controlling the color of luminescence emitted from xenon-mercury fluorescent lamps by using both the internal (axial direction) electrodes and external (radial direction) ones. A mixture containing two kinds of phosphors was coated on the inner surface of the lamp tubes. One of the mixed phosphors is excited by the resonance radiation of mercury and emits white colored light. The other is excited by vacuum ultraviolet (VUV) radiation of xenon and emits red colored light. The lamp was operated alternatively by the internal electrodes forming an axial discharge and external electrodes developing a radial discharge. The color of emitted light was changed from white to red by varying the mixture ratio of axial and radial discharges. When a lamp was operated by the external electrodes, afterglow of mercury spectra was observed for a longer time than that of xenon.