US 9,869,730 B2Granted

Magnetic detection apparatus

AssigneeMitsubishi Electric Corporation

InventorsAkihiro Oba, Masahiro Yokotani

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Abstract

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.

Claims7

Dependent claims

A magnetic detection apparatus comprising:

a magnetic moving body having a shape changing a magnetic field, the magnetic moving body rotating in sync with a rotary shaft;
magneto-resistance elements detecting a change in the magnetic field by the magnetic moving body, the magneto-resistance elements being anisotropic;
a magnet applying the magnetic field to the magneto-resistance elements;
and
a processing circuit unit having a bridge circuit including the magneto-resistance elements, the processing circuit unit detecting the change in the magnetic field acting on the magneto-resistance elements by converting a change in resistance values of the magneto-resistance elements to a change in voltages,
wherein the magneto-resistance elements are separately disposed in a rotational direction of the magnetic moving body, and
a pattern shape of each of the magneto-resistance elements is a zigzag shape having a plurality of turn-back portions oriented at an angle α relative to a direction orthogonal to a direction of the magnetic field applied to cancel a change of the direction and a magnitude of the magnetic field depending on a displacement in the rotational direction of the magneto-resistance elements relative to the magnet.

4 more elements

Dependencies are inferred from the claim text.

Facts

Application: 14/862,224Filed 23 Sep 2015
Priority: JP 2015-08815723 Apr 2015
Published: US 2016/0313410 A127 Oct 2016
Granted: 16 Jan 2018
Term ends: Not estimatedThe source records don’t support an estimate.

Classification5 codes

G01R 33/093
Magnetoresistive devices: using multilayer structures, e.g. giant magnetoresistance sensors
G01D 5/147
Using Hall-effect devices: influenced by the movement of a third element, the position of Hall device and the source of magnetic field being fixed…
G01D 5/2451
Using a variable number of pulses in a train: incremental encoders
G01R
Measuring electric variables