Methods were investigated to improve the lamp characteristics of inductively coupled electrodeless metal halide lamps to make them practical.
First, evaluating lamp efficacy by adjusting the lamp parameters showed that a lamp efficacy of 1801m/W with white color could be attained.
Second, the conditions generating free iodine and bulb deterioration, the main factors limiting the life of these lamps, were investigated. For longlifetype lamps, which had 1301m/W of lamp efficacy, the lamp lumen level did not decrease during 21000hours of overload operation (corresponding to 58000 hours of ratedload operation). These lamps thus have excellent lumen maintenance and life performance compared with conventional electrode metal halide lamps.
Third, improving circuit reliability by decreasing the Q value of the resonant circuit was investigated for long-life-type lamps which had 1451m/W of lamp efficacy. The relationship between the Q value and the lamp parameters was analyzed, and the Q value was decreased to 78% its value while maintaining the same lamp performance.