| 摘要 |
PURPOSE: To minimize energy consumption in a lamp electrode to improve efficiency by shunting the lamp by a third semiconductor switching element getting conductive while the lamp electrode is preheated and thereafter stopping a converter for a predetermined short time to ignite the lamp. CONSTITUTION: A discharge lamp 1 is shunted by a capacitor 11 or a third semiconductor switching element 12 getting conductive while electrodes 2, 3 are preheated. After the lamp electrode is preheated, a converter is stopped for a short time by turning-on and -off a transistor 19 and the shortcircuit of control of the semiconductor switching element 9 with the aid of a diode 13, capacitors 14, 15, a resistor 16, a capacitor 17 and a mono-stable multivibrator 18. This short time is shorter than a time taken for cooling the lamp electrode to the temperature lower than the radiation temperature. Further, the third semiconductor switching element 12 is a TRIAC, while the converter is stopped for a period longer than a TRIAC recovering time. |
