| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a mercury-free high-pressure discharge lamp which has a high lamp voltage and high light emission efficiency practical in using for general illumination even when a sealing pressure of xenon is relatively low, and which has excellent stability of an arc, and to provide a lighting system using the same. Ž<P>SOLUTION: The high-pressure discharge lamp includes: a translucent hermetically-sealed ceramic vessel 1; a pair of current introducing conductors 3 inserted into small-diameter cylinder parts; a pair of electrodes each having an electrode shaft part 2a and a large-diameter part 2b, wherein the electrode shaft part is connected to a tip end of the current introducing conductor and a tip end of the electrode shaft part projects from the large-diameter part and forms a projection part having a length A in a tube axis direction; an electrode mount sub coil SC having a ratio B of an outer diameter with respect to an inner diameter of the small-diameter cylinder part; an ionization medium in which rare gas is mainly xenon at 1-5 atm, contains halide of at least one of Tm and Ho, and which is sealed without containing mercury; and a sealing part 4. The numerical value A, B, and a sum of them are in predetermined ranges respectively. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
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