| 摘要 |
PURPOSE:To improve ignition characteristic of a device at low rotary speed, by utilizing a reverse current of a generating coil, applying bias to the cathode of a thyristor and virtually lowering ignition voltage of the thyristor. CONSTITUTION:Between a cathode K of a thyristor SCR and the ground G, a diode D5 is connected in parallel with reverse polarity to the SCR, and its connection point is connected to a voltage shorting diode D2 for a generating coil EXT. When a terminal (a) of the coil EXT is at plus voltage, a capacitor C is charged, while a terminal (b) is at plus voltage a reverse current i2 flows to generate forward voltage drop VFD5 in the diode D5 and lower potential of the cathode K by the VFD5 level from the earth G. Accordingly, forward voltage drop VFD3 of a diode D3 is cancelled, and if generated voltage VP of a pulser coil P for igniting the thyristor SCR becomes ignition voltage VGT, a spark is generated in an ignition plug IP to virtually lower the generated voltage VP and lower the generating rotary speed of an engine, thus a stable ignition characteristic can be obtained from at low rotary speed. |
