| 摘要 |
PROBLEM TO BE SOLVED: To provide a fluorescent lamp lighting device of a type having a DC current cutting capacitor using a high frequency inverter circuit equipped with a life end lamp detection circuit detecting a lamp when a fluorescent lamp in use comes to the life end. SOLUTION: This device 10 is composed as a series resonance lighting type, and plural fluorescent lamps FL1 to FL2, loads, are connected to the high frequency output OUT of an inverter circuit 1 via a DC current cutting capacitor C2. A life end lamp detection circuit 7 detecting the one side emission-less state at the life end of the fluorescent lamps FL1 to FL2 as the DC voltage fluctuation of a C2 fluorescent lamp side (a B point) resulting from a one side emission-less rectifying action is provided. The middle point A voltage (1/2 of a DC power source DC) of resistors R1, R2 (R1=R2) connected in series across the DC power source DC and the voltage of the point B are compared, and when current flows in the light emitting element of a bidirectional photocoupler PC1, the presence of a life end lamp is output to a detection output OUT2. |
