Internal combustion engine ignition device and igniter for same

An igniter in an internal combustion engine ignition device provided with:

• a DC power source,
• an ignition coil having a primary coil receiving the feed of power from said DC power source and through which a primary current is run and a secondary coil able to generate a high voltage in accordance with the changing ratio per time of said primary current,
• a spark plug to which high voltage is supplied from said secondary coil of said ignition coil and causing spark discharge in a combustion chamber of the engine,
• an igniter for controlling switching of said primary current of the primary coil to cause spark discharge at said spark plug, and
• an electronic control unit (ECU) for outputting an ignition signal corresponding to the ignition timing of the engine to said igniter, wherein:
• said igniter is provided with:
• a switching device able to change said primary current in accordance with the gate voltage supplied,
• a current limiting circuit for limiting the primary current running through said switching device to within a predetermined value,
• a fast gate voltage drop circuit for making the gate voltage of the switching device fast drop to an extent where spark discharge occurs at said spark plug,
• an abnormality detecting circuit for detecting an abnormal state of the ignition signal of said igniter or said electronic control unit and outputting an abnormality detection signal, and
• a slow gate voltage drop circuit having a gate voltage feed cutoff circuit for cutting off the feed of the gate voltage when said abnormality detecting circuit detects an abnormal state and a discharge circuit for discharging the gate capacitor charge of said switching device to make said gate voltage slowly drop to an extent where no spark discharge will occur at said spark plug.