| 摘要 |
PURPOSE: To provide a lighting device for a discharge lamp capable of controlling an input voltage of an inverter circuit with a simple configuration. CONSTITUTION: In an inverter circuit 23, fluorescent lamps FL1 and FL2 are lighted by a high frequency by means of switching field-effect transistors Q11 and Q12. During full lighting time when dimmer set switch SW11 is opened, the voltage of a capacitor C11 is divided by resistor R16 and resistors R15 and R16 and input to Vcon terminal of a control circuit 24 and, in the control circuit 24, the inverter circuit 23 is controlled by an ordinary output. During dimming and lighting time when the dimmer set switch SW11 is closed, a diode D11 is turned into a reverse-blocking state, the voltage of capacitor C11 is divided by the resistor R15 and resistor R16 and input to the Vcon terminal of the control circuit 24, an apparent voltage of the capacitor C11 increases higher than the voltage of the actual capacitor C11, the control circuit 24 operates the same way as the case when the input voltage has risen, thereby lowering the output of the inverter circuit 23. |
