Ignition device and structure for mounting same

An ignition device comprising:

• a power supply for discharge;
• an AC power supply for supplying AC power;
• an ignition coil which includes a primary coil and a secondary coil and which generates a high secondary voltage in the secondary coil by stepping up a voltage applied to the primary coil from the power supply for discharge;
• an ignition plug electrically connected to the secondary coil;
• an AC electrode electrically connected to the AC power supply;
• a high-voltage electrode located between the secondary coil and the ignition plug and electrically connected to the secondary coil and the ignition plug;
• an insulator disposed between the high-voltage electrode and the AC electrode;
• and
• a second insulator which covers the ignition coil and a capacitor composed of the AC electrode, the high-voltage electrode, and the insulator,
• wherein the secondary voltage and the AC power are supplied to the ignition plug via the high-voltage electrode, and
• wherein the ignition device further comprises a semiconductor device capable of permitting and stopping supply of the AC power from the AC power supply to the AC electrode, the semiconductor device being provided between the AC power supply and the AC electrode.