Abstract: A high-pressure discharge lamp includes a cathode body composed of a cathode made of tungsten or tungsten alloy and a lead rod inserted in a lead rod insertion hole of the cathode. The cathode has a carbonized layer made of tungsten carbide (W2C) formed on a surface thereof exposed to a discharge space (except for a tip portion thereof) and on an inner surface of the lead rod insertion hole. The carbonized layer contains carbon in an amount of 0.44 g/cc to 0.53 g/cc.

Abstract: A high-pressure discharge lamp includes a cathode body composed of a cathode made of tungsten or tungsten alloy and a lead rod inserted in a lead rod insertion hole of the cathode. The cathode has a carbonized layer made of tungsten carbide (W2C) formed on a surface thereof exposed to a discharge space (except for a tip portion thereof) and on an inner surface of the lead rod insertion hole. The carbonized layer contains carbon in an amount of 0.44 g/cc to 0.53 g/cc.

Abstract: A discharge lamp operating apparatus including: a discharge lamp; an operating circuit; a voltage measuring unit; a magnetic field applying unit; and a control unit, wherein the voltage measuring unit measures the voltage of power at sampling intervals, the control unit calculates an average value VL1 of a group of the measured value of the voltage as a standard and an average value VL2 of a group of the measured value of the voltage for comparison after a predetermined time has elapsed from the measurement of the measured value of the voltage measured at the beginning from the group of the measured value of the voltage as a standard, and when the difference (VL2?VL1) between the average value VL1 and the average value VL2 exceeds a predetermined value, drives the magnetic field applying unit.

Abstract: A discharge lamp operating apparatus including: a discharge lamp; an operating circuit; a voltage measuring unit; a magnetic field applying unit; and a control unit, wherein the voltage measuring unit measures the voltage of power at sampling intervals, the control unit calculates an average value VL1 of a group of the measured value of the voltage as a standard and an average value VL2 of a group of the measured value of the voltage for comparison after a predetermined time has elapsed from the measurement of the measured value of the voltage measured at the beginning from the group of the measured value of the voltage as a standard, and when the difference (VL2?VL1) between the average value VL1 and the average value VL2 exceeds a predetermined value, drives the magnetic field applying unit.