JPS5783664A - Ignition device for internal combustion engine - Google Patents

Abstract

PURPOSE:To prevent misfiring in an ignition device based on a square wave signal by controlling the device on the basis of a signal directly corresponding in the area of low rotation, to keep a constant time of electrification in the area of medium rotation, and to keep a constant time of interception in the area of high rotation. CONSTITUTION:A signal S1 is generated in a coil 2 by the rotation of a reactor 1 provided in a distributor, and converted into a square wave signal S2 by a wave-form shaping circuit 3. In the area of low rotation, the square wave signal S2 is added to an output transistor device 5 as it is by a duty control circuit 4. In the area of medium rotation, a square wave signal S3 with a fixed base width is outputted without reference to the wave-form of the sqare wave signal S2, and its time width is kept to be sufficient to obtain the energy of ignition. In the area of high rotation, a square wave signal S3' with a fixed pulse width is outputted, and a primary current S4' of a fixed interception time is generated not to overlap the preceding period in its time of electrification. Besides, the heating of an ignition coil in the area of low rotation can be restrained at the minimum level.