| 摘要 |
PURPOSE:To improve the secondary voltage of a ballast and prevent the going out of an electric discharge lamp to the fluctuation of the supply voltage by adding a series circuit which consists of a resistance and a capacitor. CONSTITUTION:A ballast 12 having the inductance L is interposed between an electric discharge lamp 11 and a power source 13, and a pulse generating device 16 for applying the pulse voltage to the electric discharge lamp 11 at the time of starting the electric discharge lamp 11 is provided, and while a series circuit having a resistance 17 and a capacitor 18 is connected in parallel with the electric discharge lamp 11. The electrostatic capacity C of the capacitor 18 is set so as to satisfy C<2/omega<2>L to the inductance L. Thereby, the secondary voltage higher than the supply voltage is generated at both end of the resistance 17 and the capacitor 18. Since this secondary voltage is applied to the electric discharge lamp 11, even if the supply voltage is fluctuated, the electric discharge lamp 11 never goes out. |
