Position detector of a brushless motor

A position detector of a brushless motor, comprising:

• a rotor magnet which includes alternately arranged N and S driving magnetic poles used for driving the motor, the rotor magnet being rotated integrally with a rotary shaft, a portion of a first of said driving magnetic poles serving as a position detection magnetic pole, said position detection magnetic pole being offset by an electrical angle of about 30.degree. from a magnetic center of the first driving magnetic pole;
• first, second and third magnetic detectors for detecting the magnetic fields of both the first driving magnetic pole and the position detection magnetic pole the magnetic detectors being opposed to the rotor magnet;
• and
• a position signal generator for synthesizing a position detection signal from output signals of the magnetic detectors wherein the position signal generator includes:
• an analog adder for adding the output signals of the first and second magnetic detectors;
• a first comparator for shaping a waveform of an output signal of the analog adder into a rectangular waveform;
• and
• a second comparator for shaping a waveform of the output signal of the third magnetic detector into a rectangular waveform;
• and
• a gate circuit for forming the position detection signal from output signals of the first and the second comparators.