| 摘要 |
PURPOSE:To positively start a discharge lamp without increasing pulse voltage not less than it is needed, by adequately selecting the breakover voltage of a semiconductor switching element by inserting the semiconductor switching element to a trigger pulse generating circuit. CONSTITUTION:When an input terminal B is changed into positive polarity, a condenser 12 is charged through a diode 13 and a winding N1 of an inductor 11, and after the polarity of a power source is inverted a terminal A is converted into positive polarity. When the instantaneous value reaches not less than the sum of the breakover voltage of a silicon trigger diode (STD) 20 and the terminal voltage of a condenser 17 after repeating such operation, the STD 20 is conducted to conduct a thyristor 14 and the charge of the condenser 12 is discharged. Thus, a large quantity of current flows through the winding N1, and high-tension pulse is induced to a winding N2. Operation as mentioned above is repeated every the cycle of the AC source, a discharge lamp 10 is started, and when the charge of the condenser 17 finishes a trigger pulse generating citcuit stops its operation. |
