| 摘要 |
PURPOSE:To expand the dimming range of the current flowing through a fluorescent lamp by making the base current of a transistor constant to stabilize self-oscillation. CONSTITUTION:The voltage of a DC variable power source 1 is applied to a transistor oscillation circuit 5, the voltage of a DC power source 19 is applied to a lighting control circuit 11. When a fluorescent lamp 3 is to be lighted, a switch 2 is turned on to operate a transistor 9, the base current flows to transistors 6 and 7 via a resistor 8 to cause self-oscillation, the voltage is applied to the fluorescent lamp 3 via a pulse transformer 10, it is lighted and the tube current flows. When the tube current is to be dimmed, the DC variable power source 1 is changed to change the voltage peak of self-oscillation, the voltage peak of the fluorescent lamp 3 is changed via the pulse transformer 10, thus the tube current is changed for dimming. The DC fixed power source 19 is provided to make the emitter voltage of the transistor 9 constant, self-oscillation is stabilized even when the range of the variable power source 1 is widened, the range of the voltage applied to the fluorescent lamp 3 is widened, and the variable range of the current flowing through the fluorescent lamp 8 can be widened. |
