PURPOSE: To prevent erroneous detection due to variation in engine rotation, etc., by providing plural projection parts for rotation angle signals and a single projection part for a reference rotation angle signal to the circumference of a timing rotor.
CONSTITUTION: The timing rotor 1 has the single tooth part (a) for the reference signal and plural tooth parts (b) for rotation angle signals. When the timing rotor 1 comes closer to a magnet pickup coil, a voltage is developed by variation in magnetic flux and this voltage is 0V where the magnet pickup coil and timing rotor 1 faces each other. The output of the magnet pickup 10 is supplied to a trigger +Vth circuit 20 and a trigger Vth circuit 30. When the output waveform of the magnet pickup 10 is greater than a plus voltage XV (threshold value), the circuit 20 generates an output for the time and also lowers a plus trigger XV to a little lower voltage when it goes up above the plus voltage XV to prevent malfunction due to noise, etc.
TAKAKUWA EIJI
NAKANO KAZUMI
