Abstract: An ignition device for an internal combustion engine, in which a current-supply terminal other than two end terminals of the second winding of the ignition coil is provided in the second winding or at the tertiary winding of the ignition coil: a diode is connected to the current-supplying terminal; a resistor is connected to one end of the secondary winding; the diode and the resistor are connected at one end in common; the spark gap of the combustion engine is connected between the common connection junction and the other end of the secondary winding; and the polarity of the diode is determined to be forward with respect to a discharge current flowing through the spark gap. An auxiliary power source may be provided in a network including the spark gap and the diode for increasing a discharge current of the spark gap.

Abstract: A spark plug igniter with an auxiliary power source, in which the auxiliary power source is a DC-DC converter including a feedback loop. A high voltage induced in a secondary winding of an ignition coil and a DC voltage generated by the converter are additionally supplied in the same polarity to a spark discharge gap. The feedback loop of the DC-DC converter comprises a feedback winding, a rectifier connected to the feedback winding through a reactance element, and means for connecting the DC output of the rectifier in series to the DC power source of the converter in the same polarity.