| 摘要 |
PURPOSE:To provide a high-frequency lighting device of a discharge lamp which can improve a long service life and the efficiency of the discharge lamp. CONSTITUTION:A high-frequency power is fed to a fluorescent lamp 1 by a lighting circuit 11 to start the lighting of the fluorescent lamp 1. The lamp current responding to the first peak voltage of a cathode drop voltage indicates the zero field discharge current IC. From the lamp current waveform and the maximum instantaneous lamp current, the % zero field discharge current is calculated by a % zero field discharge current operation circuit 14. The ratio of the % zero field discharge current is compared in a comparison circuit 15, and when the value is less than 30%, the heating current is increased by a heating control circuit 16, so as to increase the heating a filament 4 as the electrode. When the value is higher, the heating current is stopped by the heating control circuit 16 so as to stop the heating of the filament 4. |
