| 摘要 |
<p>An off-time control circuit (4) drives an output transistor (10) connected in series with a primary winding of an ignition coil (12) while controlling the off-time in each ignition period so that the ratio TilT between the period of time Ti, during which the level of primary current (ic) supplied to the primary winding of the ignition coil (12) attains a predetermined setting (ico). and the ignition period (T) can be maintained constant. The output from a current detecting resistor (11) connected to the primary winding is applied to a rising time detecting circuit (8) which detects the rising time (Tc) of the primary current (ic) from the current supply starting time to the time of attainment of the predetermined setting (ico). The off-time control circuit (4) controls the starting timing of power supply (13) to the output transistor (10) depending on the output (K2) from the rising time detecting circuit (8).</p> |
