| 摘要 |
PURPOSE:To surely start the lighting of a fluorescent lamp even at the time of dimming by detecting that an old fluorescent lamp is removed and a new one is fitted, and increasing the voltage across a starting capacitor for a fixed period. CONSTITUTION:A serial circuit of resistors 190, 200 is connected between the non-power source side of the electrode 14a of a fluorescent lamp 14 and the emitter of a switching transistor 5, and the junction of the resistors 190, 200 is connected to the base of a transistor 23 connected to a capacitor 173 via a capacitor 21. A diode 22 is connected between the base and emitter of the transistor 23. When it is detected that the fluorescent lamp 14 is newly fitted, the voltage across a starting capacitor 9 is increased for a fixed period to discharge the fluorescent lamp 14, then the voltage is immediately returned to the dimming state. Satisfactory dimming can be started even when the fluorescent lamp 14 is replaced at the time of dimming. |
