| 摘要 |
PURPOSE:To exhibit and keep the necessary lamp function continuously, by specifying the ratio between the inner diameter (d) and the outer diameter D of a ceramic tube having the inner diameter (d) longer than 20mm, thereby entirely suppressing the characteristical fluctuation, the leak from the sealing section and the crack of a light emission tube. CONSTITUTION:In a ceramic discharge lamp employing a light transmission ceramic tube as a light emission tube bulb while the openings at the opposite ends are sealed air-tightly by respectively supported blocking members and a rare gas is encapsulated to facilitate discharge of mercury and a light emission metal, it is set such that d>=20mm while 1.04<=D/d<=1.10, where (d) and D are the inner and outer diameters of the light transmission tube, respectively. Consequently, the starting performance of the ceramic discharge tube is improved to light stably within about 10min. Furthermore, the leak or crack is not recognized irrespective of shortened starting time resulting in a long term exhibition of specific light source function.
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