| 摘要 |
PURPOSE:To fix input power in a discharge lamp and suppress fluctuation photooutput for stabilizing lighting by connecting a transistor to an inductor in parallel while varying a base current of the transistor corresponding to undulation of AC power supply voltage for charging impedance of the transistor. CONSTITUTION:An inductor 144 is connected to a base circuit of a switching transistor 126, and a parallel circuit of a transistor 146, where an emitter is connected to the base side of the switching transistor 126, while the base of the transistor 146 is connected to a variable resistor 154 through a resistor 148 and a series circuit of a regulated diode 150. Then, by setting at the constant, where a variation of output of an inverter circuit 116 due to the fluctuation of power supply voltage and a variation of output power of the inverter circuit 116 due to the fluctuation of a base current of the transistor 146 are respectively cancelled, a fluctuation of input power to a discharge lamp 118 to the power supply voltage fluctuation inside a fixed range can be suppressed. Thus, stable discharge can be maintained. |
