Patent ID: 7931014

Claim:
A reverse rotation preventing circuit, the reverse rotation preventing circuit comprising: a generator output receiving circuit to which a three-phase input or a two-phase input of a generator connected to a crankshaft of an engine is inputted; a pulse receiving circuit to which one positive or one negative pulse signal is inputted per one revolution of the crankshaft; and a reverse revolution discriminating circuit arranged to discriminate a reverse revolution of the crankshaft based on an output from the generator, the reverse revolution discriminating circuit being connected to an ignition circuit; wherein the reverse revolution discriminating circuit is arranged to output an ignition prohibiting signal when a revolution speed of the crankshaft decreases after an initiation of a revolution of the crankshaft and the generator output becomes below a predetermined amount; and the reverse revolution discriminating circuit is arranged to maintain an ignition prohibiting state until a first positive pulse signal is inputted when the crankshaft is rotated by a new cranking operation.