| 摘要 |
PURPOSE:To provide possibility of dimming and prevent flickering by impressing AC voltage between a discharge start assist conductor and filament potential, and varying its frequency and/or voltage amplitude. CONSTITUTION:A high frequency high voltage generated in a secondary winding L2 is impressed on a discharge start assist conductor 2 in proximity to the outer tube of a fluorescent lamp 1, and filament windings L3, L4 of a high voltage transformer T2 are connected with filaments of fluorescent lamp. The filaments are, at the same time, connected with the secondary winding L6 of an output transformer T3 in a number-of-pulses control dimming high voltage generator circuit 105, and the DC bias potential there becomes the ground potential. Therefore, the fluorescent lamp 1 can be dimmed by varying the high frequency high voltage impressed on the assist conductor 2. It is also practicable to have dimming through utilization of the discharge characteristics of fluorescent lamp and by varying the high frequent frequency. Thus flickering is eliminated, and dimming is obtained up to a low brightness range where the brightness is zero. |
