| 摘要 |
PROBLEM TO BE SOLVED: To enhance build-up of light flux right after lighting by forming a phosphor layer containing a phosphor particle and a binder containing a quantity of alumina equivalent to a weight within the specific range as a main ingredient to the phosphor particle on the inner surface of a glass tube by sealing a discharge medium containing amalgam and noble gas in the glass tube. SOLUTION: In this fluorescent lamp, a discharge medium containing amalgam and a noble gas, providing a lower mercury vapor pressure than that of pure mercury, is sealed in a glass bulb, discharged is caused in the glass tube and a phosphor layer containing a phosphor particle and a binder containing an amount of alumina equivalent to 0.5-1.5 wt.% as a main ingredient with respect to the phosphor particles is formed on the inner surface of the glass bulb. If the amount of alumina used for the binder in the phosphor layer is limited within a fixed range, a temporarily insufficient condition of the mercury in the discharge space of the fluorescent lamp which has been caused by the mercury vapor pressure of amalgam at a build-up time can be dissolved, and satisfactory build-up characteristics of light flux is provided, at the initial lighting of the fluorescent lamp.
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