| 摘要 |
PROBLEM TO BE SOLVED: To provide an external electrode type discharge lamp capable of lowering temperature of a lighting external electrode without bringing troubles when jointing the external electrode and a glass bulb. SOLUTION: The external electrode type discharge lamp is provided with: a cylindrical external electrode 12 equipped with a first end part 12a and a second end part 12b separated from each other in a peripheral direction; a glass bulb 11 jointed to the external electrode 12 while inserted into the external electrode 12 and emitting light through voltage application on the external electrode 12; and a protrusion 13 fitted to an end part area 21 approaching at least either the first end part 12a or the second end part 12b of inner surfaces facing the glass bulb 11 of the external electrode 12, and a height H of the protrusion 13 is higher than a value of difference between an outer diameter OD of the glass bulb 11 and an inner diameter ID of the external electrode 12 before the glass bulb 11 is inserted. COPYRIGHT: (C)2011,JPO&INPIT
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