| 摘要 |
PROBLEM TO BE SOLVED: To compatibly eliminate the dark discharge of a fluorescent lamp and realize the deeply dimmed lit condition. SOLUTION: In a fluorescent lamp dimming apparatus, an AC power supply 1 is connected to a fluorescent lamp 3 through a ballast 2, a phase control element 4 to control the dimming of the fluorescent lamp 3 by controlling the phase to the ballast 2 is provided, a phase control circuit 5 so supply the phase control signal to the phase control element 4 is provided, and the phase control signal to be outputted by the phase control circuit 5 is the time span control signal to determine the ON-time span of the phase control element 4 in each half-cycle of the AC power supply 1. A phase control signal detection circuit 6 is provided, and the phase control signal detection circuit 6 turns off an opening/closing element 7 interposed between the AC power supply 1 and the ballast 2 when the circuit detects that no time span control signal is present. |
