| 摘要 |
PROBLEM TO BE SOLVED: To surely prevent the excessive heating of an electrode sealing part and a base in the last stage of lifetime of a fluorescent lamp by connecting a temperature protecting element in series to an external lead wire of an electrode at a part near an electrode sealing part inside a base part of a fluorescent lamp, and cutting off the current on a temperature protecting element at the last stage of lifetime of the fluorescent lamp. SOLUTION: A base part 12 of a fluorescent lamp is made of plastic, and surrounds an electrode sealing part of each arc tube 1, 4 and an end of each arc tube 2, 3, and the base part 12 is fixed to the arc tubes 1-4 by cement or an adhesive. External lead wires 13-16 of the electrodes are connected to lead terminals 17-20 respectively, and a temperature protecting element 21 is connected in series to an electrode lead wire 15, and housed in the base part 12. When the electrode sealing part is excessively heated at the least stage of lifetime of the fluorescent lamp, the temperatures protecting element 21 cuts off the current so as to prevent the excessive heating of the electrode sealing part and the base part 12. Range of the cutting temperature of the temperature protecting element 12 is desirably set at 150-400 deg.C. |
