| 摘要 |
PURPOSE:To obtain an optimum conduction time of electric current, by smoothing primary current detection output of an ignition coil, converting the output through an A/D converter and feedback controlling the current conduction time of the primary coil in such a manner as to obtain always a fixed value of this converted value. CONSTITUTION:A timing generator circuit 5 controls electric conduction of a primary current in an ignition coil 7 by a switching circuit 6. A level detector circuit 1 detects a signal b to be at least a preset value and outputs a signal c. An integrating circuit 2 switches charge and discharge to output a smoothed signal d to an A/D converter 3, here the signal is converted into a digital value. An arithmetic unit 4 firstly initializes a time of electric conduction, then reads the digital value to correct the electric conduction time. Thereafter, this loop is repeated to perform feedback control of the conduction time with an A/D value always to a target value, thus an optimum conduction time of current is always obtained. |
