Starting Transient Characteristics of Metal Halide Lamps

This paper aims at investigating the effects of the lamp current and power on the electrical behavior, the spectral distribution and the produced luminance. Based on the results observed, the starting transient characteristics can be well understood and the times for entering thermal equilibrium and the steady-state light output can be defined in a more reasonable manner. Experimental evidence shows that the glow-to-arc transition stage takes most of the transient period, and the starting time of a metal halide lamp can be effectively shortened by increasing the lamp current during the glow-to-arc transition stage. More importantly, a specifically-regulated operating power enables the lamp to further enhance luminance, and hence to reduce the starting transient period remarkably.