| 摘要 |
An object is to provide an extra-high pressure mercury lamp in which wear of an electrode is kept small even if a temperature of an electrode on the side of an opening portion of a reflector of an arc tube is increased to be higher than that of an electrode on the side of a neck portion of the reflector to generate a difference in temperature between both electrodes of the arc tube. An extra-high pressure mercury lamp 10 according to the present invention is an extra-high pressure mercury lamp 10 of AC lighting system provided with an arc tube 1 including a first electrode 3a positioned on the side of an opening portion 20 of a reflector 5 and a second electrode 3b positioned on the side of a neck portion 5a of the reflector 5 and including mercury sealed inside, where, when AC lamp current is supplied to the extra-high pressure mercury lamp 10 to perform lighting, a current pulse having the same polarity as that of the AC lamp current is superimposed on the AC lamp current, and pulse width of the current pulse to the first electrode 3a is made larger than that of the current pulse to the second electrode 3b. |
