Patent ID: 8776769

Claim:
A plasma ignition device comprising: an ignition plug mounted on an combustion engine; a breakdown discharge circuit configured to generate a first voltage by stepping up a first power supply voltage and apply the generated first voltage to the ignition plug to cause a breakdown discharge in a discharge space in the ignition plug; and a plasma discharge circuit configured to accumulate electric energy supplied from a power supply and apply the accumulated electric energy to the ignition plug as a current to bring a gas in the discharge space into a plasma state so that the gas in the plasma state is injected to a combustion chamber of the combustion engine during the breakdown discharge to cause ignition; wherein the plasma discharge circuit includes an energy accumulating section, and an energy supplying section configured to supply the electric energy to the energy accumulating section during a time period immediately before the breakdown discharge circuit applies the first voltage to the ignition plug, wherein the energy supplying section includes a first step-up coil comprising a first primary coil applied with a second power supply voltage and a first secondary coil, and a first switching element to open and close the first primary coil to generate a second voltage in the first secondary coil, wherein the energy accumulating section includes first and second capacitors connected in parallel to each other through a rectifying element, the first capacitor being charged with the second voltage for a first time period, the second capacitance being charged with a third power supply voltage lower than the second voltage for a second time period, and wherein the first capacitor has a first capacitance, and the second capacitor has a second capacitance larger than the first capacitance, the second time period being longer than the first time period.