Abstract An ignition coil energizing circuit is provided which has a signal generator for generating an output signal having a frequency corresponding to an engine rotational speed, a switching circuit connected to an ignition coil, a current detector for detecting a current flowing through the ignition coil, a duty control for supplying to the switching circuit a control signal having a duty cycle corresponding to a duty cycle of an output signal from the signal generator and controlling a conduction state of the switching circuit, and a current control circuit for controlling the switching circuit in response to an output signal generated from the current detector and maintaining a current flowing through the current detector at a predetermined value. The ignition coil energizing circuit also has a timer for generating an output signal when the switching circuit is detected to be on over a predetermined period of time and a current supply circuit for supplying a gradually increasing current to the current detector in response to an output signal of the timer.
An ignition coil energizing circuit comprising: a signal generating circuit for generating an output signal having a frequency corresponding to an engine rotational speed; a switching circuit connected to an ignition coil; a current detecting circuit having a resistive means connected in series to said switching circuit, for producing an output signal corresponding to a voltage drop across said resistive means; a first control circuit for supplying to said switching circuit a control signal having a duty cycle corresponding to a duty cycle of an output signal from said signal generating circuit and controlling a conduction state of said switching circuit; a second control circuit for controlling a conduction state of said switching circuit in response to an output signal generated from said current detecting circuit and maintaining a current flowing through said current detecting circuit at a predetermined value while said switching circuit is being turned on by the control signal of said first control circuit; a timer for generating an output signal responsive to said switching circuit being kept on for more than a predetermined period of time by said first control circuit; and a current supply circuit for supplying a gradually increasing current to said resistive means in response to an output signal of said timer.
Claim 2
Dependent Claim
209 words
An ignition coil energizing circuit comprising: a signal generating circuit for generating an output signal having a frequency corresponding to an engine rotational speed; a switching circuit connected to an ignition coil; a current detecting circuit having a resistive means connected in series to said switching circuit, for producing an output signal corresponding to a voltage drop across said resistive means; a first control circuit for supplying to said switching circuit a control signal having a duty cycle corresponding to a duty cycle of an output signal from said signal generating circuit and controlling a conduction state of said switching circuit; a second control circuit for controlling a conduction state of said switching circuit in response to an output signal generated from said current detecting circuit and maintaining a current flowing through said current detecting circuit at a predetermined value while said switching circuit is being turned on by the control signal of said first control circuit; a timer for generating an output signal responsive to said switching circuit being kept on for more than a predetermined period of time by said first control circuit; and a current supply circuit for supplying a gradually increasing current to said resistive means in response to an output signal of said timer.
Claim 3
Dependent Claim
54 words
An ignition coil energizing circuit according to claim 1, wherein said timer supplies an output signal to said current supply circuit in response to a turn-on output signal from said first control circuit turning on said switching circuit when detecting that the turn-on output signal is kept generated for a predetermined period of time.