| 摘要 |
PROBLEM TO BE SOLVED: To provide a discharge lamp lighting device which can be improved as to input current distortion and inhibit generation of moving streaks on a fluorescent lamp at low temperatures. SOLUTION: An input power factor improving circuit comprises a capacitor C4 , which serves as an impedance element connected between the point of connection between a capacitor C3 and a discharge lamp La and the positive output end of a diode bridge DB, and a diode D3 connected between the positive output end of the diode bridge DB and a capacitor C1 . A frequency modulation control circuit 3 fixes an oscillating frequency for a predetermined time after the input of power on the basis of an output of a timer circuit 5 and sets the peak factor of lamp current to a second peak factor higher than a first peak factor that is a peak factor for normal lighting; after the predetermined time has elapsed the control circuit 3 modulates frequency according to an output of a source voltage detecting part 2 and controls switching elements Q1 , Q2 so that the peak factor of the lamp current attains the first peak factor. |
