Nippondenso Co., Ltd.

Ichirou Izawa

Seiki Aoyama

Susumu Kuroyanagi

Yasuaki Makino

Tomoatsu Makino

Kenji Yagi

Tatsuo Tamura

Shigehiro Kasumi

Yasuki Makino

A magnetic detection apparatus detects movement of an object having a nonuniform system of teeth by means of magneto-electric conversion devices, wherein technical problems such as too large an amplified output signal, a nonuniform pulse period and a complicated circuit configuration can be solved. A plurality of uniform triangular teeth are formed on the circumference of a gear at equal angular intervals, and in a predetermined region a trapezoidal tooth is formed, where the height of the trapezoidal tooth is smaller than the height of the uniform teeth but greater than half their height. The magnetized surface of a bias magnet facing the gear generates a bias magnetic field directed toward the gear. Magneto-resistive devices are provided in the bias magnetic field. Variations in state of the bias magnetic field generated by the bias magnetic magnet when the gear is rotated are converted into an output electrical signal by the magneto-resistive devices. A binary conversion circuit converts the electrical signal output into a binary signal. Receiving the binary signal, a processing circuit detects a reference position and the rotational direction of the object.

Magnetic detection apparatus for detecting movement of an object having

A magnetic detector which is small in size and is capable of preventing the occurrence of deformation in the waveform representing a change in the resistance. A bias magnet 2 is adhered to the support plate 1. A bias magnetic field is generated by the bias magnet 2 toward a gear 7. A substrate 3 is adhered onto the support plate 1, and magneto resistance elements are formed on the substrate 3 by vacuum evaporation. The magneto resistance elements are disposed in parallel with the magnetized surface of the bias magnet 2. The magneto resistance elements are disposed being tilted by about 45 degrees with respect to a vector that is in parallel with the N-pole surface of the bias magnet 2 in the bias magnetic field and is directed toward the outer peripheral edge. Due to the revolution of the gear 7, a change in the resistance takes place in the magneto resistance elements due to a change in the vector which is parallel with the N-pole surface of the bias magnet 2 in the bias magnetic field generated by the bias magnet 2 towards gear 7 and is directed toward the outer peripheral edge.

Magnetic detector having a bias magnet and magnetoresistive elements

A peak hold circuit 11 holds a peak value of an output signal from a rotating angle sensor 6. A bottom hold circuit 12 holds a bottom value of the output signal from the rotating angle sensor 6. A threshold value is set from the peak value by the peak hold circuit 11 and the bottom value by the bottom hold circuit 12 by resistors 24 to 27, analog switches 28 and 29 and a NOT circuit 31. A comparator 10 compares the output signal of the rotating angle sensor 6 with the set value thus set, and outputs a binary signal (digitized signal) in accordance with the comparison result.

MRE sensor signal detector

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Anjo, Japan

Ichirou Izawa