| 摘要 |
PROBLEM TO BE SOLVED: To provide an electrode structure for a high pressure discharge lamp excellent in environmental conservation or occupational health and safety, in which exhaustion and breakage of a cathode can be suppressed to the minimum even when the discharge lamp is used at a large current, the discharge lamp can be used for a long period in the state in which the lighting operation of the discharge lamp is kept stable, the cathode can be easily formed, a control unit for a power source can be simplified, a carburizing portion not at all adversely influences on a service life of the discharge lamp, and the discharge lamp can be used for a long period in the stable lighting operation by carburizing components on an anode side. SOLUTION: In a discharge lamp to be used while maintaining a high input, in which an anode 3 and a cathode 6 are disposed opposite to each other inside an arc tube 2a expanded at the center of a bulb 2, the cathode 6 is formed by doping metal having a high melting point with metallic substance including at least one kind of rare-earth metal oxide and is provided with a tapered portion 6a having an inclined surface toward the discharging side, wherein a non-carburized portion 6B is formed on the tip side of the tapered portion 6a while a carburized portion is formed at the inclined surface, thus providing an electrode structure for a high voltage pressure lamp 1.
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