| 摘要 |
PURPOSE:To prevent a rush current and to shorten the charging time in a flash discharge lamp by reducing the conducting angle of a triac at the initial charging time and increasing the rate of increase of the conducting angle as the number of cycles increases. CONSTITUTION:After a power source 2 is thrown, a capacitor 72 is charged at the prescribed voltage, while a capacitor 108 is charged by an FET110. Thus, a transistor 102 is conducted to charge a capacitor 82, but the gate voltage of a PUT74 is sufficiently high at the initial charging time. When the charging voltage of the capacitor 72 reaches an anode voltage, the PUT74 is conducted. Then, a transistor 88 is conducted, and the triac 6 is conducted by the operations of transformers 96-1, 96-2, thereby charging a double voltage circuit 20. As the number of cycles increases, the charging voltage of the capacitor 108 is raised by the FET110, and the capacitor 82 is abruptly charged. Thus the gate voltage is abruptly lowered, with the result that the conducting time of the transistor 88 can be gradually accelerated. |
