Abstract: An apparatus for detecting information indicative of the rotation of an engine is disclosed in which a multiplicity of magnetic poles are formed on a track along the circumferential periphery of a rotating member driven by an engine, thus detecting a rotational reference position and a rotational angle from the rotational reference position of the engine. A rotational reference sensor and an angle sensor for generating a signal representing a change in magnetic fluxes by detection of the magnetic fluxes from the track are arranged in opposition to the track in spaced relation from each other along the axis of the rotating member. Some of the magnetic poles on the track which are opposed to the rotational reference sensor are omitted, so that a signal representing the rotational reference position is generated in the case where the angle sensor detects magnetic fluxes but the rotational reference sensor fails to detect the same.

Abstract: The specification discloses a first and a second rotary disk fixed together, each disk having a magnetic pole on its circumference, which disks rotate in the vicinity of a fixed magnetic head; the fixed magnetic head provides an electrical output signal each time a magnetic pole passes near it and, thus, said electrical output signal indicates a rotational angle and/or the number of rotations of said disk. Said magnetic head operates on a new principle developed from parametric excitation.

Abstract: Apparatus for detecting an external magnetic field comprises a magnetic sensor which produces para-magnetic oscillations and includes an elongated member of an electrically conductive material and a thin magnetic film disposed thereabout. Alternative embodiments of the invention are presented in each of which the detection of an external magnetic field by the sensor results in a change in the oscillating state. In a first embodiment, the sensor is maintained normally in an oscillating state of a given domain and thus a given phase; when the sensor is subjected to an external magnetic field of appropriate intensity and polarity, the magnetization of the sensor shifts from the first domain to the second domain and accordingly there is produced a change or reversal in phase of the oscillatory output derived from the sensor. In that change of phase, the sensor output passes through a zero voltage value which is detected for providing an indication of the sensing of the external magnetic field.

Abstract: A magnetic substance detecting device is disclosed as being capable of parametric oscillation, and including a magnetic sensor formed of an elongated wire with a magnetic thin film plated on the wire, the film being of uniaxial magnetic anisotropy and having a magnetic hard axis in its axial direction and a magnetic easy axis in its circumferential direction. The magnetic substance to be detected is coupled with a magnetic or electrical circuit associated with the magnetic oscillation domain of the magnetic wire of the magnetic sensor to convert the state of the oscillation output of its detecting coil, thus detecting the magnetic substance.