| 摘要 |
PROBLEM TO BE SOLVED: To provide a lighting device for a fluorescent lamp which can prevent a flame failure, blackening in the morning and reduction of a life time by improving startability of a fluorescent lamp when starting it at a low temperature. SOLUTION: A direct current power supply circuit 2, a parallel resonance circuit of capacitor 5 inductor 6, and a switching element 3 are connected in series. A series circuit containing a primary winding of a current transformer 7, a capacitor 8 to cut a direct current, a ballast inductor 9 and a fluorescent lamp 11 is connected in parallel with the parallel resonance circuit (5.6). A starting capacitor 10 is connected between non-power supply side terminals of a fluorescent lamp 11. A secondary winding of the current transformer 7 is connected to a control terminal of the switching element 3 through a capacitor 17 for setting a preheating frequency and a capacitor 18 for setting a lighting frequency. Thereby, a lighting device for a self-exciting fluorescent lamp is structured. A capacitor 33 for setting a preheating frequency at a low temperature to change the preheating frequency mentioned above is connected in parallel with the capacitor 17 for setting the preheating frequency mentioned above. |
