Mitsubishi Denki Kabushiki Kaisha

Mitsubishi Electric Corporation

Mitsubishi Electric Cornoration

Masahiro Yokotani

Izuru Shinjo

Naoki Hiraoka

Yasuyoshi Hatazawa

Yoshinori Tatenuma

Wataru Fukui

Takuji Nada

Hideki Shimauchi

Yutaka Ohashi

Hideki Umemoto

Yuji Kawano

Hiroshi Sakanoue

Akira Koshimizu

Hiroshi Kobayashi

Shigeki Tsujii

Ryouichi Sasahara

Naohiro Mishiro

Shunichi Wada

Mitsuru Koiwa

Akira Takashima

Takafumi Hara

Tatsuya Fukami

Yasuyoshi Hori

Fumito Uemura

Kazuyasu Nishikawa

Masami Matsumura

Manabu Tsukamoto

Noriaki Hayashi

Tadao Takaishi

Tetsuo Amano

Akihiro Oba

Tokuo Marumoto

The magnetic detection device includes: a first magnetic rotary body which rotates about a rotation shaft and has an outer circumferential portion which is a magnetic body; a second magnetic rotary body has an outer circumferential portion which is a magnetic body; a magnet which has a magnetization direction along the axial direction; a first magneto-resistive element provided on another side in the axial direction of the magnet; a second magneto-resistive element provided on one side in the axial direction of the magnet; a first magnetic guide provided between the magnet and the first magneto-resistive element; and a second magnetic guide provided between the magnet and the second magneto-resistive element, wherein the outer circumferential portion of the first magnetic rotary body and the outer circumferential portion of the second magnetic rotary body cause different magnetic fields between the magnet and the respective outer circumferential portions.

Magnetic detection device

There is provided a magnetic detection apparatus in which based on a second comparison signal or a first comparison signal, a second analog/digital conversion circuit or a first analog/digital conversion circuit converts a second amplification signal or a first amplification signal into a digital value at a time when the peak value of the first amplification signal or the second amplification signal is detected or at a time when the bottom value of the first amplification signal or the second amplification signal is detected, as the case may be, and that can implement at least one of actions in which based on comparison between the digital value converted and a predetermined reference value, a second threshold value adjusting apparatus or a first threshold value adjusting apparatus adjusts a second threshold value or a first threshold value, as the case may be.

Magnetic detection apparatus

Included are an element having a magnetic tunnel junction structure configured such that an insulating layer is sandwiched between a pinned layer having a fixed magnetization direction and a free layer having a magnetization direction that varies freely, a magnet, and a rotating magnetic moving body having an irregular shape that induces change in the magnetic field. When, using the element as a reference, the magnetization direction of the pinned layer is set as an X axis direction, a direction perpendicular to the X axis direction and perpendicular to a plane of the pinned layer is set as a Z axis direction, and a direction perpendicular to an XZ plane constituted by the X axis direction and the Z axis direction is set as a Y axis direction, the magnetic moving body is disposed opposite the element in the Y axis direction via a gap relative to the element.

Magnetic detection apparatus with a tunnel magnetoresistive element

In a magnetic detection apparatus that prevents the output waveform from deviating regardless of whether two magneto-resistance elements are displaced relative to a magnet or accurately disposed relative to the magnet, the above two magneto-resistance elements are angled in consideration of a change in the direction of application of the magnetic field during displacement of the positional relationship and the anisotropy of the magneto-resistance elements so that the magneto-resistance elements are oriented in a direction in which the deviation of the output waveform caused by a change in the magnitude of application of the magnetic field during displacement of the positional relationship is cancelled, thereby preventing the detection accuracy of a magnetic moving body (detection target) being affected even if the magneto-resistance elements are displaced relative to the magnet due to manufacturing variations.

A magnetic detection device has: a magnetic moving body which rotates about a rotating shaft and in which N-poles and S-poles are disposed alternately on an outer periphery thereof; magnetoresistive elements that are disposed at a spacing from the outer peripheral surface of the magnetic moving body; a signal processing unit that processes signals from the magnetoresistive elements; and a magnet that applies a bias magnetic field to the magnetoresistive elements. The magnetization direction of the magnet is parallel to the rotating shaft of the magnetic moving body. The magnetoresistive elements are disposed in a plane perpendicular to the magnetization direction of the magnet, and are disposed at a fixed spacing in the radial direction of the magnetic moving body.

Rotation of a magnetized rotor is detected in a highly accurate manner without depending on a magnetic pole pitch of N and S poles of the magnetized rotor. To that end, a magnetic detection device includes a magnetoresistive element that is formed of a fixed layer made of a ferromagnetic material whose magnetization direction is fixed and a free layer made of a ferromagnetic material whose magnetization direction can be freely changed, with a non-magnetic middle layer sandwiched between the layers, and arranged therein maintaining a gap between the element and the outer circumferential surface of the magnetized rotor in which the N and S poles are alternately arranged along the outer circumference rotating around a rotation shaft, wherein the magnetoresistive element is arranged in such a way that a plane on which the fixed layer is formed is in a plane including the rotation shaft.

Magnetic detection device and on-vehicle rotation detection device equipped with the same

A magnetic detection apparatus includes a first comparison circuit that waveform-shapes the amplitude of a detection signal from magneto-electric transducers by DC coupling, a third comparison circuit that waveform-shapes the detection signal by AC coupling, an oscillation circuit having a natural frequency, a control circuit that counts the output of the first comparison circuit by using the oscillation means, and a selection circuit that selects the output of the first comparison means and the output of the second comparison means. The control circuit counts rising from the next rising or falling from the next falling of an output rectangular wave of the first comparison circuit, and provides output to the selection circuit at the time point at which the count value reaches a desired value. The selection circuit selects and outputs the output rectangular wave of the first comparison circuit or the third comparison circuit.

In a magnetic detection apparatus, a magnetic detection sensor generates a sensor output signal whose high level and low level have different potentials in accordance with the moving direction of a magnetic moving object, and a computer unit includes three comparator circuits and detects the output signal of the magnetic detection sensor with three levels of comparison threshold values, so that the moving direction of the magnetic moving object can be detected accurately without any delay.

The magnetic sensor in the invention is arranged to detect a change of magnetic field caused by a movement of the magnetic movable by a magnetic sensor element arranged with a gap to the magnetic movable, to convert the detected change of magnetic field by first and second bridge circuits into electric signals, to generate first and second rectangular-wave signals by first and second comparator circuits depending upon the electric signals, and to form a signal having at least four levels by a signal forming circuit, thereby detecting a moving direction of the magnetic movable depending upon a level-change order in the signal. This makes it possible to detect a rotating direction of the magnetic movable rapidly and correctly.

Magnetic sensor

A magnetic detection device is provided in which a first signal is outputted in accordance with the mutual phase relationship between the output of a first magnetoelectric conversion output circuit and the output of a second magnetoelectric conversion output circuit that are based on the movement, in forward direction, of a detection subject, thereby generating a pulse of a high leveland a low level; a second signal is outputted in accordance with the mutual phase relationship between the output of the first magnetoelectric conversion output circuit and the output of the second magnetoelectric conversion output circuit that are based on the movement, in forward direction, of the detection subject; an output signal processing circuit for generating a pulse of a high leveland a low levelis provided; and not only the pulse of the high leveland the low leveldoes not cross the other comparison level, but also the pulse of the high leveland the low leveldoes not cross the one comparison level.

A magnetic detector, wherein the magnetic/electric conversion element is constituted by at least six segments symmetrically arranged in a direction in which the magnetic moving body rotates maintaining a predetermined pitch with respect to the center line of the magnet, first and second bridge circuits are constituted so as to produce outputs accompanying the rotation of the magnetic moving body, and a third bridge circuit is constituted so as to produce an output accompanying the rotation of the magnetic moving body, and wherein a comparison level of a comparator circuit that shapes the waveform of a differential output signal of the first and second bridge circuits is adjusted relying upon an output signal of the third bridge circuit.

Magnetic detector maintaining high detection precision without affected by the temperature characteristics of the sensing element

A magnetic detection apparatus can be improved in its product yield. The magnetic detection apparatus includes a resin compact having a the magnet arranged in opposition to an object to be detected for generating a magnetic field, an IC chip with a magnetic detection part built therein for detecting a change in the magnetic field in accordance with movement of the object to be detected, and an IC package in which a lead frame having the IC chip installed thereon is sealed with a resin. A method for manufacturing such a magnetic detection apparatus includes a signal adjustment step for adjusting a signal generated from the magnetic detection part in a state in which the magnetic field is applied to the magnetic detection part to correct a deviation of the signal of the magnetic detection part generated in accordance with a relative displacement between the magnetic detection part and the magnet.

Method of manufacturing a magnetic detection apparatus

The invention provides a magnetic detector that exerts no influence on detection accuracy of a magnetic movable body, being a detected body, even if relative positions of magnetic resistance elements and a magnet are out of alignment due to variation occurred in manufacturing process. A magnetic detector includes: a magnetic field detection part constructed of at least two magnetic resistance elements; a magnet for applying a magnetic field to the magnetic resistance elements; a magnetic movable body for changing the magnetic field that is generated by the magnet; and a processing circuit part for outputting a signal based on the change in resistance values of the magnetic resistance elements due to the change in the magnetic field; and in which a shape of the magnetic resistance elements is symmetric with respect to a point.

Magnetic detector

The magnetic sensor in the invention includes a detecting section that detects a change of magnetic flux due to a movement of the magnetic movable, comparator circuits constituting a converting section that converts a change of magnetic flux detected by the detecting section into an electric amount, and a D-FF circuit device, in a sensor unit having a power-supplying power terminal VB, a ground terminal GND and an output terminal VOUT. A current control section is provided to change the amount of current flowing through at least one of the power terminal and the ground terminal, correspondingly to a moving direction of the magnetic movable. Thus, a moving direction of the magnetic movable can be determined depending upon the amount of current.

A magnetic detection apparatus is able to make a selection between AC coupling and DC coupling thereby to improve the accuracy of a final output signal corresponding to a magnetic movable element, thus making it possible to ensure excellent detection performance. The magnetic detection apparatus with a sensor composed of magnetoresistive elements () for detecting the strength of a magnetic field includes a first comparison circuit () that has a first comparison level (VR), and waveform shapes the amplitude of a detection signal (C) from the magnetoresistive elements () through DC coupling, a second comparison circuit () that has a second comparison level (VR), and waveform shapes the amplitude of the detection signal C through DC coupling, and a third comparison circuit () that has a third comparison level VR, and waveform shapes the amplitude of the detection signal C after AC coupling.

Growing community of inventors

Tokyo, Japan

Masahiro Yokotani