| 摘要 |
PURPOSE:To obtain a discharge lamp lighting device, which can change quantity of modulation of a discharge lamp and a vision so as to correspond to each other. CONSTITUTION:At the time of controlling the modulation, quantity of modulation is set by a PWM modulation setting circuit 3, and the modulation is performed on the basis of this set quantity of modulation. A light emitting diode LED 1 is made to emit the light by the PWM modulation setting circuit 35, and with this emission, a photo-transistor PTr 1 is turned on. In the case where the phototransistor PTr 1 is turned off, a modulation control means 37 sets a charge curve with a resistor R2 and a capacitor C5, and in the case where the photo-transistor PTr 1 is turned on, the modulation control means 37 sets a discharge curve with a variable resistor R1 and the capacitor 5. Voltage corresponding to the quantity of modulation is outputted by the modulation control means 37. Since quantity of modulation to be set and the output of an inverter circuit are not linearly changed but changed like natural logarithm, quantity of modulation and visual brightness of a fluorescent lamp FL can be linearly changed. |
