An ignition device is provided, which can boost an electromagnetic wave supplied by a resonance structure, and cause a discharge by enhancing a potential difference between a discharge electrode and a ground electrode, and even though such a structure of the ignition device, a downsize and a thickness reduction, specifically, the thickness reduction can be achieved. On a main surface of a rectangular insulting substrate (2), an input electrode (3), a coupling electrode (4), a discharge electrode (6), and a ground electrode (7), are provided. The input electrode (3) is connected to an outside terminal on one shorter side. The coupling electrode (4) is capacity-coupled with the input electrode (3). The discharge electrode (6) is connected to the coupling electrode (4) on the other shorter side through a coupling line (5). The ground electrode (7) is, on both longer sides of the main surface of the rectangular insulating substrate (2), capacity-coupled with the coupling electrode (4) and capacity-coupled with the coupling line (5), and extended to the other shorter side. A resonance circuit includes a capacitor constituted by the capacity coupling and an inductor constituted by the coupling line (5). Thereby, the electromagnetic wave supplied from the outside terminal into the input electrode is resonated, a potential difference between the discharge electrode (6) and the ground electrode (7) is enhanced, and then, a discharge is caused.

A multipoint spark plug includes side electrodes provided in a pair so as to extend in a lengthwise direction of a tip end portion via a gap, and an intermediate electrode provided in the gap between the pair of side electrodes such that a plurality of ignition gaps are formed in the lengthwise direction of the tip end portion. An electrode holding portion is formed from separate parts that hold the side electrodes and the intermediate electrode, respectively, so as to insulate the side electrodes and the intermediate electrode from the main body portion, and the respective parts thereof project into the combustion chamber from the tip end portion.

A multipoint spark plug includes side electrodes provided in a pair so as to extend in a lengthwise direction of a tip end portion via a gap, and an intermediate electrode provided in the gap between the pair of side electrodes such that a plurality of ignition gaps are formed in the lengthwise direction of the tip end portion. An electrode holding portion is formed from separate parts that hold the side electrodes and the intermediate electrode, respectively, so as to insulate the side electrodes and the intermediate electrode from the main body portion, and the respective parts thereof project into the combustion chamber from the tip end portion.

A multipoint spark plug for igniting an air-fuel mixture in a combustion chamber of an engine includes a main body portion that is formed in a flattened shape and inserted into an insertion hole of the engine such that a tip end portion thereof opposes the combustion chamber, a pair of side electrodes provided via a gap in a lengthwise direction of the tip end portion, and at least one intermediate electrode provided in the gap between the pair of side electrodes such that a plurality of ignition gaps are formed in the lengthwise direction of the tip end portion.

A dual spark plug may include: a cap plug formed of an insulation material; an upper body formed of an insulation material and coupled with the cap plug; a lower body integrally formed with the upper body and provided at an outer side of the upper body; a pair of plug center electrodes provided inside the cap plug; a pair of upper center electrodes provided inside the upper body and electrically connected with the pair of plug center electrodes; insulation caps provided to wrap the pair of plug center electrodes, respectively; and a pair of ground electrodes extended from opposite sides of the lower body and disposed at a predetermined distance from the pair of upper center electrodes, respectively.

A dual spark plug may include: a cap plug formed of an insulation material; an upper body formed of an insulation material and coupled with the cap plug; a lower body integrally formed with the upper body and provided at an outer side of the upper body; a pair of plug center electrodes provided inside the cap plug; a pair of upper center electrodes provided inside the upper body and electrically connected with the pair of plug center electrodes; insulation caps provided to wrap the pair of plug center electrodes, respectively; and a pair of ground electrodes extended from opposite sides of the lower body and disposed at a predetermined distance from the pair of upper center electrodes, respectively.

An ignition system includes an ignition coil with a primary winding and a secondary winding having a terminal for providing a high voltage (HV). An electrode arrangement of an igniter includes first and second HV electrodes coupled to the terminal of the secondary winding. The igniter also has at least one ground electrode. A first spark gap is defined between the first HV electrode and the at least one ground electrode, and a second spark gap is defined between the second HV electrode and the at least one ground electrode. A first capacitor is disposed in-line between the first HV electrode and the terminal of the secondary winding and a second capacitor disposed in-line between the second HV electrode and the terminal of the secondary winding of the ignition coil. The ignition system includes a driver module coupled to a terminal of the primary winding, for driving the ignition coil.

A dual spark plug may include: a metal body made of metal material, an insulating body provided inside of the metal body and made of an insulating material, a pair of central electrodes provided inside of the insulating body and electrically connected with an ignition coil, and a pair of ground electrodes respectively extended from both ends the metal body, and spaced apart from ends of the pair of central electrodes by a predetermined distance.

A dual spark plug may include: a metal body made of metal material, an insulating body provided inside of the metal body and made of an insulating material, a pair of central electrodes provided inside of the insulating body and electrically connected with an ignition coil, and a pair of ground electrodes respectively extended from both ends the metal body, and spaced apart from ends of the pair of central electrodes by a predetermined distance.

An igniter having at least two electrodes spaced from each other by an insulating member having a substantially continuous surface along a path between the electrodes. The electrodes extend substantially parallel to each other for a distance both above and below said surface. The insulating member has a channel (recess) for receiving at least a portion of a length of at least one of said electrodes below and to said surface of the insulating member. The surface of the insulating member may preferably be augmented with a conductivity enhancing agent. The insulating member and electrodes are configured so that an electric field between the electrodes at said surface does not have abrupt field intensity changes, whereby when a potential is applied to the electrodes sufficient to cause breakdown to occur between the electrodes, discharge occurs at said surface of the insulating member to define a plasma initiation region.