| 摘要 |
PROBLEM TO BE SOLVED: To provide a high pressure mercury lamp which suppresses early blackening on a discharge vessel and maintains stable intensity of lighting for long time. SOLUTION: The alternating current lighting type high pressure mercury lamp (10) is equipped with: a discharge vessel (11) which comprises sealing portions (13 and 14) connected to both ends of a light emitting tube portion (12) and also comprises quartz glass; and a first electrode (20)and a second electrode (25) which are placed along a tube axis direction so as to face each other in the light emitting tube portion (12) and are prepared by forming electric polar bodies (22 and 27) on the tips of electrodes (21 and 26), and also contains 0.16 mg/mm<SP>3</SP>or more of mercury, 1×10<SP>-6</SP>to 1×10<SP>-2</SP>μmol/mm<SP>3</SP>of halogen, and inert gas sealed in the light emitting tube portion (12). A first heat insulation member (24) and a second heat insulation member (29) are placed on the perimeter of an external surface region surrounding each of the first electrode (20) and the second electrode (25) in the discharge vessel (11), and the heat capacity of the first heat insulation member (24) is 30-80% of the heat capacity of the second heat insulation member (29). COPYRIGHT: (C)2010,JPO&INPIT
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