| 摘要 |
PROBLEM TO BE SOLVED: To provide an external electrode type fluorescent lamp having flat light distribution characteristics although a phosphor film formed on the inner periphery side of a glass tube has inclined film thickness characteristics. SOLUTION: In this external electrode type fluorescent lamp 110, the phosphor film 2, the film thickness of which gradually changes to a thin film thickness from a thick film thickness in the inner periphery side of the glass tube 1 from its one end part TK to the other end part TN along its tube axis, is formed, a noble gas is filled in the inside space of the glass tube as a discharge medium 4, and a pair of belt-like external electrodes 5, 6 having longitudinal sawtoothed fringe sides, the effective width of which changes so that the effective width becomes long on the thin film side TN of the phosphor film and the effective width becomes short on the thick film side TK along the axial direction of the tube, are installed apart from each other on the periphery side of the glass tube. COPYRIGHT: (C)2007,JPO&INPIT
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