| 摘要 |
PROBLEM TO BE SOLVED: To provide a discharge lamp with heightened illumination intensity maintenance rate. SOLUTION: From among a plurality of peaks of OH between wavelengths of 305 nm to 310 nm including the wavelength of 306.4 nm at time of glow discharge by supplying an electrode 23 of a high-pressure discharge lamp 5 with 2.5 mA current at glow voltage of 20 V, a spectrum of the highest wavelength of 305 nm is to be A, and a spectrum of the wavelength 404.7 nm of Hg is to be B. By sealing in OH so that A/B is larger than 0.35, tungsten spattered from the electrode 23 makes a compound with oxygen and halogen inside the luminous tube 21, with which, an oxy-halogen cycle returning to the electrode 23 is activated, to bring forth a high maintenance rate of illumination intensity.
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