| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a high pressure discharge lamp in which translucent polycrystalline alumina ceramics of a translucent airtight container is superior in mechanical strength and thermal shock resistance, and an illumination device using this. <P>SOLUTION: The high pressure discharge lamp is provided with surrounding part 1a which is composed of the translucent polycrystalline alumina ceramics and which surrounds a discharge space, and a pair of small diameter cylindrical parts 1b, 1b which extendedly exist from both ends of a tube axial direction, and equipped with the translucent airtight container 1 in which the alumina average particle diameter of the outer surface region R1 in the cross-sectional face of the wall thickness direction of the surrounding part is smaller by 8% or more than the alumina average particle diameter of the residual region R2, a pair of electrodes 2, 2 sealed in the translucent airtight container, and an ionized medium sealed in the translucent airtight container. <P>COPYRIGHT: (C)2008,JPO&INPIT |
