| 摘要 |
PROBLEM TO BE SOLVED: To provide a series resonance type fluorescent lamp lighting apparatus capable of scanning stable lighting with sufficient illuminance under low temperature circumstances suppressing fluctuation of filament power caused by variation of filament resistance values of the fluorescent lamp. SOLUTION: A circuit constitution of a series resonance type fluorescent lamp lighting apparatus is that power supply connecting ends of filaments R1 and R2 in both poles of a fluorescent lamp 5 are connected, through an inductor L as a load circuit to a high frequency output of an inverter circuit 3 converting direct current output coming through a rectification smoothing circuit 2 with an commercial alternate current power supply 1 as an input to high frequency, and a first capacitor C1 is connected to the other ends of the filaments R1 and R2 not to be connected to the power supply 1. With the circuit constitution, a high frequency output Vo is obtained by self oscillation and it is raised by a series resonance of the inductor L and the capacitor 1. In this apparatus, especially, a second capacitor C2 is connected in parallel with the filament R1 of the fluorescent lamp 5 and a third capacitor C3 is connected in parallel with the other filament R2 to thereby form a bypass, and accordingly filament power is kept almost stable absorbing the variation of the filament resistance values. |
