| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a metal halide lamp of which a container is made of ceramic of polycrystal alumina, in which short lifetime is prevented without applying a special treatment, even if the ceramic contains lanthanum. <P>SOLUTION: The metal halide lamp has a container 12 made of ceramic consisting of polycrystal alumina, and has an electrode body 21 arranged inside, and is provided with an arc tube 4 containing at least one kind of rare earth metal out of dysprosium (Dy), thuliumn (Tm), and holmium (Ho) as a light-emitting substance. The composition ratio of the total rare earth metal to the total light-emitting substance (provided that mercury is excluded) is 5 [mol%] or more and 35 [mol%] or less, and the content of lanthanum (La) contained in the ceramic constituting the container 12 is 100 [ppm] or more and 300 [ppm] or less. <P>COPYRIGHT: (C)2009,JPO&INPIT |
