| 摘要 |
PROBLEM TO BE SOLVED: To provide an external electrode type discharge lamp having long service life by preventing a blackened part on an arc tube inner wall from developing in the tube axis direction of an arc tube. SOLUTION: An external electrode type discharge lamp with electrodes 2 laid on the external surface of both ends of a glass tubular arc tube 1, has a barrier 4 made of an insulator on the inner tube wall thereof near the ends 2a of the electrodes 2. The barrier 4 is formed as a body which is separate from the arc tube 1 and fastened to the inner wall thereof. Alternatively, the arc tube 1 is contracted in diameter for forming the barrier 4.
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