PURPOSE: To store a normal reference signal position obtained when an engine speed is greater than a specific speed and to regenerate and output a reference signal based upon the stored reference signal position when less than the specific engine speed, by providing a reference signal regenerating circuit.
CONSTITUTION: When an engine rotates at a speed high enough to output the reference signal of a shaping logical circuit normally, the reference signal appears at the output terminal 25 of a reference signal regenerating circuit 5 as it is and the reference signal position is stored in a counter 220; when the engine rotates at a low speed where the reference signal of the shaping circuit is outputted erroneously, the reference signal is regenerated by the correct reference signal position stored in the counter 220 and outputted to the output terminal 25, thus obtaining the invariably correct reference signal.
ARAKAWA MIYAO
SATOU SHINKOU
TAKENAKA AKIHIKO
