Magnetic sensor

Patent metadata

Field	Value
Publication number	US-10401441-B2
Application number	US-201815891576-A
Country	US
Kind code	B2
Filing date	Feb 8, 2018
Priority date	Mar 24, 2017
Publication date	Sep 3, 2019
Grant date	Sep 3, 2019

Abstract

A magnetic sensor includes a magnetic field conversion unit and a magnetic field detection unit. The magnetic field conversion unit receives an input magnetic field containing an input magnetic field component in a direction parallel to Z direction, and generates an output magnetic field containing an output magnetic field component in a direction parallel to X direction. The magnetic field detection unit receives the output magmetic field and generates an output signal corresponding to the input magnetic field component. The magnetic field detection unit includes first and second magnetic detection elements. When misalignment occurs between the magnetic field conversion unit and the magnetic field detection unit, one of the strength of a portion of the output magnetic field component that the first magnetic detection element receives and the strength of a portion of the output magnetic field component that the second magnetic detection element receives increases while the other decreases.

First claim

What is claimed is:

1. A magnetic sensor comprising a magnetic field conversion unit and a magnetic field detection unit, wherein
the magnetic field conversion unit is formed of a soft magnetic material and configured to receive an input magnetic field and generate an output magnetic field, the input magnetic field containing an input magnetic field component in a direction parallel to a first virtual straight line,
the magnetic field detection unit is configured to receive the output magnetic field and generate an output signal corresponding to the input magnetic field component,
the output magnetic field contains an output magnetic field component in a direction parallel to a second virtual straight line intersecting the first virtual straight line, the output magnetic field component varying depending on the input magnetic field component,
the magnetic field conversion unit has an end face located at an end in the direction parallel to the first virtual straight line,
a first element-placement region and a second element-placement region lie in a virtual plane that includes the second virtual straight line and intersects the first virtual straight line,
each of the first and second element-placement regions lies only either inside or outside an end face projection region, the end face projection region being a region formed by vertically projecting the end face of the magnetic field conversion unit onto the virtual plane,
one of an inclination of a conversion efficiency at a given first point in the first element-placement region and an inclination of the conversion efficiency at a given second point in the second element-placement region has a positive value while the other has a negative value, where the conversion efficiency at a given point in the virtual plane refers to the ratio of a strength of the output magnetic field component at the given point to a strength of the input magnetic field component, and the inclination of the conversion efficiency at the given point refers to the ratio of a variation amount of the conversion efficiency at the given point to a positional variation amount of the given point when the given point is moved in one direction parallel to the second virtual straight line,
the magnetic field detection unit includes a first magnetic detection element and a second magnetic detection element each of which is configured to receive a portion of the output magnetic field component,
the first magnetic detection element is disposed to intersect the first element-placement region and not to intersect the second element-placement region,
the second magnetic detection element is disposed to intersect the second element-placement region and not to intersect the first element-placement region,
the first magnetic detection element generates a first detection value corresponding to the portion of the output magnetic field component received by the first magnetic detection element,
the second magnetic detection element generates a second detection value corresponding to the portion of the output magnetic field component received by the second magnetic detection element, and
the output signal depends on a composite value obtained by compositing the first detection value and the second detection value.

2. The magnetic sensor according to claim 1 , wherein each of the first and second magnetic detection elements is shaped to be elongated in a direction parallel to a third virtual straight line that is located in the virtual plane and orthogonal to the second virtual straight line.

3. The magnetic sensor according to claim 1 , wherein
the first magnetic detection element is a first magnetoresistive element,
the second magnetic detection element is a second magnetoresistive element,
the first detection value is a resistance value of the first magnetoresistive element,
the second detection value is a resistance value of the second magnetoresistive element, and
the composite value is a composite resistance value of the first magnetoresistive element and the second magnetoresistive element.

4. The magnetic sensor according to claim 3 , wherein the first magnetoresistive element and the second magnetoresistive element are connected in parallel.

5. The magnetic sensor according to claim 3 , wherein the first magnetoresistive element and the second magnetoresistive element are connected in series.

6. The magnetic sensor according to claim 1 , wherein the second virtual straight line is orthogonal to the first virtual straight line.

7. The magnetic sensor according to claim 1 , further comprising a substrate for holding the first magnetic detection element and the second magnetic detection element.

8. The magnetic sensor according to claim 1 , wherein a ratio of an absolute value of the inclination of the conversion efficiency at a second center of gravity to an absolute value of the inclination of the conversion efficiency at a first center of gravity is within a range of 0.48 to 2.1, where the first center of gravity refers to the center of gravity of a portion of the first element-placement region that intersects the first magnetic detection element, and the second center of gravity refers to the center of gravity of a portion of the second element-placement region that intersects the second magnetic detection element.

9. The magnetic sensor according to claim 1 , wherein
the first element-placement region lies only outside the end face projection region,
the second element-placement region lies only inside the end face projection region, and
the end face projection region has an edge located between the first and second element-placement regions and orthogonal to the second virtual straight line.

10. The magnetic sensor according to claim 1 , wherein
the magnetic field conversion unit includes a yoke,
the yoke has a yoke end face located at an end in the direction parallel to the first virtual straight line,
the end face projection region includes a yoke end face projection region formed by vertically projecting the yoke end face onto the virtual plane, and
the first element-placement region and the second element-placement region lie only outside the end face projection region, and are located on opposite sides of the yoke end face projection region in the direction parallel to the second virtual straight line.

11. The magnetic sensor according to claim 1 , wherein
the magnetic field conversion unit includes a yoke,
the yoke has a yoke end face located at an end in the direction parallel to the first virtual straight line,
the end face projection region includes a yoke end face projection region formed by vertically projecting the yoke end face onto the virtual plane,
the first element-placement region and the second element-placement region lie only inside the yoke end face projection region,
the yoke end face projection region has a first edge and a second edge located at opposite ends in the direction parallel to the second virtual straight line,
the first element-placement region is located between the first edge and the second element-placement region, and
the second element-placement region is located between the second edge and the first element-placement region.

12. The magnetic sensor according to claim 1 , wherein
the magnetic field conversion unit includes a first yoke and a second yoke,
the first yoke has a first yoke end face located at an end of the first yoke in the direction parallel to the first virtual straight line,
the second yoke has a second yoke end face located at an end of the second yoke in the direction parallel to the first virtual straight line,
the first element-placement region is closer to

Assignees

• Tdk Corp

Inventors

• Uchida Keisuke
• Makino Kenzo
• Hirabayashi Hiraku

Classifications

• G01R33/093 Primary

  using multilayer structures, e.g. giant magnetoresistance sensors (thin magnetic films H01F10/00) · CPC title

• G01R33/096

  anisotropic magnetoresistance sensors · CPC title

• G01R33/095 Primary

  extraordinary magnetoresistance sensors · CPC title

• G01R33/072

  Constructional adaptation of the sensor to specific applications · CPC title

• G01R33/098

  comprising tunnel junctions, e.g. tunnel magnetoresistance sensors · CPC title