SHORT ARC TYPE DISCHARGE LAMP LIGHTING DEVICE

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PROBLEM TO BE SOLVED : To provide a short arc type ultra-high pressure mercury lamp having a long service life by preventing tube wall blackening. SOLUTION : This short arc type ultra-high pressure mercury lamp is composed of : a short arc type discharge lamp composed by oppositely disposing a pair of electrodes 1 at a space not more than 2 mm in an arc tube 11 formed of quartz glass, and by enclosing, in the arc tube 11, mercury not more than 0.15 mg/mm3, a rare gas and halogen in the range of 1×10-6-1×10-2 μmol/mm3; and a power feed device for feeding a D.C. current to the discharge lamp in lighting startup and thereafter feeding an A.C. current. In the discharge lamp, at least one of a pair of the electrodes is composed of a molten large-diameter part formed by melting the tip of a coil wound around a shaft, and a coil formed by being continuously and integrally connected to the rear side of the molten large-diameter part. The D.C. current fed to the discharge lamp by the power feed device is characterized in that its initial value is 0.3-0.6 times as large as a rated current, and its subsequent value is 1.0-2.0 times.