| 摘要 |
PURPOSE:To control properly the conduction timing of a main thyristor which works to discharge the charge within a capacitor by providing an auxiliary thyristor connected in series with the gate and cathod circuit of the main thyristor for assisting the discharge by the main thyristor. CONSTITUTION:When a voltage having a waveform (a) is produced at a pair of capacitor charging coils 1 and 2 by the ratation of an engine, the capacitor 5 is charged. The charging of the capacitor 5 is carried out mainly by the coil 2 having a larger number of windings during a low-speed rotation of the engine and, to the contrary, during a high-speed rotation of the engine the charging is carried out mainly by the coil 1 having a smaller number of windings. At a time point T2, an adverse preventing signal having a waveform (b) is produced at a trigger coil 3 to put the auxiliary thyristor 11 to be inoperative. After that, when a half-wave output on the capacitor charging side of the third cycle within one rotation of the engine is produced at the coils 1 and 2, an ignition signal is produced at a time point T4 at the coil 3 to put the auxiliary thyristor 11 to be conductive. Then, at a time point T5, the main thyristor 9 becomes conductive to generate a spark L at an ignition plug 8 via an ignition coil 7. |
