PURPOSE: To prevent the breakage of one switching element due to the short circuit current by triggering the other switching element after detecting the cutoff of one switching element in a composite engine ignition device combined with the current cutoff system and the capacity discharge system.
CONSTITUTION: When a contact breaker 4 is closed, a transistor 10 is turned on by an ignition signal generating circuit 9, the primary current flows in the primary winding 3a of an ignition coil 3. A capacitor 8 is charged by a DC-DC converter 6. On the other hand, when an engine is rotated and a contact breaker 4 is opened, a monostable multivibrator 11 outputs a pulse with the preset width. The outputted pulse is differentiated by a capacitor 12 and triggers a thyristor 7, thus charges of the capacitor 8 are discharged to the primary winding 3a of the ignition coil 3. As a result, the high voltage is generated on the secondary winding 3b of the ignition coil 3, an ignition plug 5 is ignited.
KOIWA MITSURU
MORITA SHINGO
