An ignition system for an internal combustion engine has a power source, a transformer having first and second primary windings and a secondary winding, a connector extending from the secondary winding and adapted so as to connect with a terminal of the spark plug of the internal combustion engine, and electronic spark timing circuit cooperative with the transformer so as to activate and deactivate voltage to the first and second primary windings. The first and second primary windings are connected to the power source such that the transformer produces an alternating voltage output from the secondary winding of between 1 kHz and 100 kHz and a voltage of at least 20 kV. A forced push-pull inverter is cooperative with the electronic spark timing circuit so as to fix a frequency of voltage to the first and second primary windings.

An ignition system that uses a technique capable of restraining radiation of noise caused by discharge of a spark plug in the ignition system. The ignition system includes a spark plug and a power supply section. The spark plug is attached to an engine head. The power supply section has a battery having a ground terminal, and an ignition coil which transforms a voltage of the battery and supplies a transformed voltage to the spark plug. In the ignition system, a metallic shell of the spark plug is fixed to the engine head while being electrically insulated from the engine head through an insulator an electrically conductive path is connected to the metallic shell, and the electrically conductive path is electrically connected to the ground terminal of the battery while being electrically insulated from the engine head.

An ignition system that uses a technique capable of restraining radiation of noise caused by discharge of a spark plug in the ignition system. The ignition system includes a spark plug and a power supply section. The spark plug is attached to an engine head. The power supply section has a battery having a ground terminal, and an ignition coil which transforms a voltage of the battery and supplies a transformed voltage to the spark plug. In the ignition system, a metallic shell of the spark plug is fixed to the engine head while being electrically insulated from the engine head through an insulator an electrically conductive path is connected to the metallic shell, and the electrically conductive path is electrically connected to the ground terminal of the battery while being electrically insulated from the engine head.

A triggerable spark gap, a switching circuit and a method for manufacturing a triggerable spark gap are disclosed. In an embodiment, a triggerable spark gap includes a trigger electrode, an adjacent electrode at the trigger electrode, a counter electrode and a gap between the counter electrode and the adjacent electrode, wherein a distance between the trigger electrode and the adjacent electrode is less than a distance between the trigger electrode and the counter electrode, wherein the distance between the trigger electrode and the counter electrode is less than a distance between the adjacent electrode and the counter electrode, wherein the counter electrode and/or the adjacent electrode includes a first phase including a first material and a second phase including a second material, and wherein the second material has a lower electron work function than the first material.

An igniter includes a switch element and a switch control apparatus. An ignition signal IGT is input to an input line of the switch control apparatus. A high-frequency filter removes high-frequency noise from the input line. A voltage comparator compares an output voltage V.sub.FIL of the high-frequency filter with a reference voltage V.sub.REF, so as to generate a judgment signal S.sub.DET. A driving stage controls an on/off switching operation of the switch element according to the judgment signal S.sub.DET. An off-state dead-time circuit prohibits the switch element from turning off during a predetermined dead time after the judgment signal S.sub.DET transits to a negated level that corresponds to the off state of the switch element.

An igniter includes a switch element and a switch control apparatus. An ignition signal IGT is input to an input line of the switch control apparatus. A high-frequency filter removes high-frequency noise from the input line. A voltage comparator compares an output voltage V.sub.FIL of the high-frequency filter with a reference voltage V.sub.REF, so as to generate a judgment signal S.sub.DET. A driving stage controls an on/off switching operation of the switch element according to the judgment signal S.sub.DET. An off-state dead-time circuit prohibits the switch element from turning off during a predetermined dead time after the judgment signal S.sub.DET transits to a negated level that corresponds to the off state of the switch element.

A semiconductor apparatus is provided, including a power semiconductor element, a cutoff condition detection portion which detects whether a predetermined cutoff condition is met, a reset portion which outputs a reset signal that instructs to reset during a predetermined period in response to an input of the control signal turning the power semiconductor element on, a latch portion which is reset in response to the reset signal and latches that an occurrence of the cutoff condition is detected after the reset, a cutoff circuit which controls the gate of the power semiconductor element to be at an OFF potential in response to the latching of the occurrence of the cutoff condition by the latch portion, and a prevention circuit which prevents the gate of the power semiconductor element from being at an ON potential during a period of reset of the latch portion even if the cutoff condition is met.

A semiconductor apparatus is provided, including a power semiconductor element, a cutoff condition detection portion which detects whether a predetermined cutoff condition is met, a reset portion which outputs a reset signal that instructs to reset during a predetermined period in response to an input of the control signal turning the power semiconductor element on, a latch portion which is reset in response to the reset signal and latches that an occurrence of the cutoff condition is detected after the reset, a cutoff circuit which controls the gate of the power semiconductor element to be at an OFF potential in response to the latching of the occurrence of the cutoff condition by the latch portion, and a prevention circuit which prevents the gate of the power semiconductor element from being at an ON potential during a period of reset of the latch portion even if the cutoff condition is met.

A non-thermal equilibrium plasma ignition plug including a tubular metallic shell having an axial hole extending along an axial line, an insulator disposed in such a manner as to form a gap in cooperation with a wall surface of the axial hole at a forward end portion of the metallic shell, and a center electrode held at the center of the insulator, and generates nonequilibrium plasma in response to voltage applied thereto from a power supply. The insulator has a plurality of depressions or protrusions formed on a surface thereof which faces a discharge space therearound.

A non-thermal equilibrium plasma ignition plug including a tubular metallic shell having an axial hole extending along an axial line, an insulator disposed in such a manner as to form a gap in cooperation with a wall surface of the axial hole at a forward end portion of the metallic shell, and a center electrode held at the center of the insulator, and generates nonequilibrium plasma in response to voltage applied thereto from a power supply. The insulator has a plurality of depressions or protrusions formed on a surface thereof which faces a discharge space therearound.