| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide such a structure in a short arc type discharge lamp which has a cathode and an anode disposed opposite with each other inside an arc tube, the anode having a diameter-reduced part at its lower end which is contracted in diameter toward the lower end side and the anode having a through hole formed therein the lower end of which opens in the diameter-reduced part, with the anode placed in an upper part in order for the lamp to be lighted vertically, that a convection current gas inside the arc tube flows down in the through hole from an upper to a lower side, so that a gas at a lower temperature than the other flows in the through hole, allowing the anode to be cooled effectively. <P>SOLUTION: The lower end opening of a through hole has a diameter-expanded part, the peripheral part on the outward side in the radial direction of the diameter-expanded part expanding outward in the radial direction; and, in a cross section including a center axis of an anode and the through hole, the contour line at the top of the diameter-expanded part is retracted from the contour line of the diameter-reduced part. <P>COPYRIGHT: (C)2012,JPO&INPIT |
