| 摘要 |
PROBLEM TO BE SOLVED: To solve the environmental problem by unleading a tubular bulb product, and to improve the sustention rate of light flux by suppressing blackening caused by reaction between Na ion contained in glass an Hg contained in discharge gas or fluorescent material. SOLUTION: With a fluorescent lamp, equipped with a main tube 1 with gas for discharge enclosed, a layer of fluorescent material 2 applied inside of the main tube 1 and with a stem section 4 fitted on both ends of the main tube 1 and equipped with an electrode 3, glass constituting at least the main tube 1 is composed, by way of example, of 60 to 75% by mass of SiO2 , 1 to 5% by mass of Al2 O3 , 1 to 5% by mass of Li2 O, 0 to 0.1% by mass of Na2 O, 1 to 15% by mass of K2 O, (provided, Li2 O+Na2 O+K2 O should be between 5 and 15% by mass), 0.5 to 5% by mass of CaO, 0.5 to 5% by mass of MgO, 0.5 to 10% by mass of SrO, 0.5 to 7% by mass of BaO, (provided, CaO+MgO+ SrO+BaO should be between 2 and 20% by mass) and PbO is practically not contained.
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