Patent ID: 7644698

Claim:
An ignition device which performs a non-equilibrium plasma discharge ignition of a fuel mixture in a combustion chamber of an internal combustion engine comprising: a first electrode; a second electrode; an insulating member which is formed from a dielectric substance, interposed between the first electrode and the second electrode, and which promotes non-equilibrium plasma discharge between the insulating member and one of the first electrode and the second electrode when an alternating current is impressed between the first electrode and the second electrode; and an alternating current impressing device which is configured to control a discharged energy of non-equilibrium plasma discharge; wherein the internal combustion engine performs operation in a first operation region in which an engine rotation speed is not greater than a predetermined speed and an engine load is not greater than a predetermined load, and in a second operation region in which the engine rotation speed or the engine load is greater than that of the first operation region, and wherein the alternating current impressing device is configured to: set the discharged energy of the non-equilibrium plasma discharge in the first operation region greater than the discharged energy of the non-equilibrium plasma discharge in the second operation region; and set the discharged energy of the non-equilibrium plasma discharge to increase as the engine load decreases and the engine rotation speed increases in the first operation region.