| 摘要 |
PURPOSE:To prevent blackening of a tube end by making have the specific relation between the distance from the end of a filament to the glass tube inner wall and the distance from the filament center to the glass end of the filament supporting stem of a fluorescent lamp. CONSTITUTION:A fluorescent lamp is formed of a glass tube 1, electrode filament supporting stem 2 and a filament 3, to which an electrode emitter is applied. And it is so set up that, when the distance from the end of the filament 3 to the inner wall of a glass tube 1 shall be (d), while the distance from the center of the filament 3 to the glass end of the filament supporting stem 2 shall be (l), the relation: 1/2<=d/l<=3/2 shall be satisfied. Accordingly, the generation rate of the tube end blackening to be caused by sticking of scattered substances to the inner wall of the glass tube 1 can be reduced by decreasing the distance (l) from the filament center to the glass end of the filament supporting stem. |
