Patent ID: 7348782

Claim:
An ignition device for producing a spark discharge in an ignition plug of an internal combustion engine, the ignition device comprising: an ignition coil having a primary winding and a secondary winding for generating a voltage across the secondary winding to generate a spark discharge in the spark plug in response to an ignition signal, the spark discharge causing a current to flow; a voltage applying means for applying a voltage between the ignition plug and a ground so that a reverse current flows in a reverse direction opposite to that of the current caused by the spark discharge; a detecting means for detecting the reverse current; and an outputting means for outputting a signal when the reverse current exceeds a preset threshold, wherein the outputting means sets the preset threshold to a first threshold for a detection of a smolder on the ignition plug and to a second threshold for a detection of a burning condition of an air-fuel mixture in the internal combustion engine, the second threshold being smaller than the first threshold.