| 摘要 |
PURPOSE:To reduce the starting voltage and to improve the luminous efficiency by forming a metal halide lamp of 250W class asigning the inside diameter of a luminous tube, a tube wall load, outside diameter of electrode shaft, and outside diameter of electrode coil in specific ranges. CONSTITUTION:A pair of main electrodes 2, 3 and an auxiliary electrode 4 are provided in a luminous tube 1 of quartz glass, and mercury, metal halide, and starting rare gas are sealed. The inside diameter of the luminous tube 1 is asigned to 15 to 17mm., the tube wall load 15 to 22W, the outside diameter d1 of electrode shafts of electrodes 2, 3 0.5 to 0.7mm., and the outside diameter d2 of the electrode coil 1.7 to 3.0mm., to form a metal halide lamp of 250W class. Thus 200V or less of the starting voltage, 85% or higher of the luminous flux maintaining ratio after 3,000hr operation, and 90lm/W or more of luminous efficiency can be atained, and these lamp performances are improved. |
