Metal halide lamp having amount of metal halide per unit volume within a specified range

摘要

A metal halide lamp comprising a generally ellipsoidal discharge space 24 having a pair of electrodes 22A, 22B where the discharge space comprises at least mercury, a starter gas and a metal halide 32. The lamp is prevented from fizzling out as the amount of metal halide per unit volume falls within a predetermined range. The amount of metal halide enclosed per unit volume may fall within a range of 0.006-0.01mg/žl (6-10 mg/cc) or more specifically 0.007- 0.009 mg/žl (7-9 mg/cc). The amount of mercury enclosed in the discharge space may be within 0.5-1 mg. The volume of the discharge space may be at least 20žl (0.02 cc) and preferably not more than 50 žl (0.05cc). The metal halide may comprise scandium iodide and sodium iodide in the weight ratio of 4:1 to 7:3. The ratio of L to the input power P of the discharge vessel may fall within a range of 0.05-0.1 mm/W. The input power P to the lamp may be 35W.