An apparatus for detecting displacements of existing movable bodies made of ferromagnetic materials and magnetized by external magnetic fields, comprising a magnetic sensor disposed in the vicinity of the movable body for detecting change in the magnetic field caused by the motion of the body, and a processor for converting the outputs of the magnetic sensor into pulse signals.

A star wheel, typically the starter gear of an internal combustion engine is magnetically coupled to a stationary pickup, for example a coil-core or yoke combination, a Hall generator, or the like. Upon rotation of the gear, or star wheel, sequential signals will be induced in the pickup which, related to time, provide an output signal representative of speed. To determine an angular reference position, an additional magnetically responsive reference element is included in the magnetic circuit formed by the stationary pickup and the teeth of the star wheel, to additionally modify the reluctance of the pickup-star wheel magnetic circuit, and change the characteristic of the output signal, for example by a phase jump, a discrete output level jump, or the like. The reference element may be a pin of soft iron, or of the material having soft iron characteristics, a pre-magnetized pin, or the like, exposed to the yoke arms of a pickup surrounding the star wheel, or otherwise magnetically coupled to the pickup.

The invention relates to a device for measuring the angular position of a gear in a digital ignition system of an internal combustion engine, wherein an origin sensor responsive to the passage by of a pre-set tooth of a gear, is connected to one of inputs of a pulse former having a second input to which an output of a rectifier and filter circuit is connected; and an input of the rectifier and filter circuit is coupled to the output of an angle pulse sensor.

A signal generating apparatus comprising a bistable magnetic device which alters its magnetic state when the density of magnetic flux to which it is subject passes through a predetermined value, and detecting means providing an output signal responsive to a change of magnetic state of the bistable device. A conducting means for magnetic flux subjects the bistable magnetic device to magnetic flux conducted therethrough and comprises a first portion providing a path of high permeability and a second portion providing a path of alterable permeance for varying the reluctance of the conducting means and the density of magnetic flux to which the bistable device is subject. An energizing means provides a controllable magnetic field for inducing magnetic flux in the conducting means and provides a flux density sufficient to alter the state of the bistable device with the variation of reluctance of the conducting means.

A revolving speed detecting device for use with a rolling contact bearing having a rotary ring and a fixed ring. It has a magnetic ring provided on the peripheral surface thereof with a plurality of teeth at equal pitches and mounted on the rotary bearing ring. A sensor made of soft ferrite or by laminating a plurality of silicon steel plates is mounted on the fixed bearing ring opposite to the teeth of the magnetic ring. A coil is wound around the sensor. A high-frequency voltage generator is connected to the coil. A detecting device for detecting the output voltage of the coil is also connected to the coil.