| 摘要 |
PURPOSE:To detect an angle of rotation accurately, by amplifying an output voltage of a magnetoelectric conversion means arranged directly facing a magnetic rotor rotating while synchronizing a crank shaft of an internal combustion engine with an amplifying circuit having a small amplification factor while a driving voltage of the conversion means is inputted into the circuit as bias voltage through a variable resistance. CONSTITUTION:When a cylindrical magnet ring 14 is provided on a magnet rotor 16 rotating while synchronizing a crank shaft of an internal combustion engine, the ring is made up of a lamination of a first magnetizing belt 22, a second magnetizing belt 24 and a third magnetizing belt 26. Moreover, the number of N and S poles provided on the respective magnetizing belts are varied beforehand to prevent changes in the output of a magnetoelectric conversion means 20 comprising hall elements arranged facing them otherwise caused gradually at lower position. Then, an angle of rotation detecting circuits the same in the structure each comprising the magnetoelectric conversion means 20, a differential amplification circuit 28 and a comparator circuits 30, all having variable resistances 20i, as opposed to these magnetizing belts are provided and an output of the means 20 is inputted into the circuits 28 as bias voltage while being used as reference voltage of the circuits 30 to detect the zero- crossing position faithfully.
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