| 摘要 |
PROBLEM TO BE SOLVED: To provide a high pressure discharge lamp of a long using life in which thoria (Th) can be supplied stably to the cathode tip over a long time after lighting the lamp, and in which generation of a flicker phenomenon is suppressed for a long time. SOLUTION: The high pressure discharge lamp is that in which an anode 14 and a cathode 13 are oppositely arranged in a bulb, the cathode 13 is tungsten containing thorium oxide, a carbonized layer A composed of tungsten carbide is formed on a surface except the tip on the anode 14 side. At the cathode 13, an electron emitter 17 composed of tungsten containing thorium oxide is arranged so as to be contacted with the cathode, and in the electron emitter 17, at a contacted region to be contacted with at least the cathode 13, the carbonized layer A composed of tungsten carbide is formed. COPYRIGHT: (C)2008,JPO&INPIT
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