| 摘要 |
A discharge lamp is provided to prevent the breakage of a discharge lamp constituting member or its equipment at the edge part, thereby preventing the inflow of the impurities into the discharge lamp. A discharge lamp comprises a first electrode which has a cylindrical body part(12) and a cone-shaped front end part(11); and a second electrode which carries out the discharge between the first electrode, wherein the front end part is provided with the front end surface(21) carrying out discharge, the side surface having an outer circumference smaller than the outer circumference of the body part, and a plurality of radial groove parts(31) extended from the front end surface along the side surface part so as not to reach the body part. The extension line of the groove parts is not crossed with the body part and the front end part.
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