| 摘要 |
PURPOSE:To enable a metal halide lamp which has a low starting voltage, a high luminous flux maintenance rate and a long life by facilitating the shift from glow electric discharge to arc electric discharge at starting during the life of the lamp. CONSTITUTION:A pair of electrodes, the distance between which is below 30mm., are provided within both ends of an emission tube. A metal halide lamp is constituted by charging the emission tube with mercury, a metal halide and Penning gas which principally consists of neon. The above electrode is constituted of a coil part consisting of an outer coil 19 and an inner coil 20, and an electrode core bar 18 the end of which protrudes from the coil part. Tungsten wire used for forming the above outer and inner coils 91 and 20, is a double coil 21 or a triple coil 22. In addition, the ratio (D/W) (mg/W) of the weight (D)(mg) of the above electrode to the electric power (W) (w) of the lamp is restricted to within the range of 0.5-0.9. By the means mentioned above, the starting voltage of the lamp can be reduced, and the luminous flux maintenance rate and the life of the lamp can be improved. |
