HIGH-PRESSURE DISCHARGE LAMP, HIGH-PRESSURE DISCHARGE LAMP OPERARING DEVICE, AND HEADLAMP DEVICE FOR AUTOMOBILES

摘要

A high−pressure discharge lamp, a high−pressure discharge lamp operating device using the same, and a headlamp device for automobiles are disclosed. No mercury is used substantially and the discharge flickering is reduced. The high−pressure lamp comprises a discharge vessel (1) having a gas−tight vessel (1a) in which a discharge space (1c) is defined and a pair of electrodes (2, 2) disposed at both ends of the discharge space (1c), opposed to each other, and spaced by a distance of 5 mm or less and a discharge medium sealed in the gas−tight vessel (1a), containing no Hg, but containing halogenides of luminescent metals including at least two kinds of iodides of Na, Sc, and rare earth metals and Xe under three or more atmospheres. The high−pressure discharge lamp is operated with a lamp power of 50 W or less during stable operation. The lamp satisfies mathematical formula (1) (T2/A>1011) expressing the relationship between the electrode temperature T (°C) during stable operation at a point 0.3 mm away from the end of the electrode (2) toward the root and the amount of free iodine produced A (mol/cc) when the lamp is turned off after a 100−hour operation.