CN108717169B

CN108717169B - Two-dimensional magnetic field sensor

Info

Publication number: CN108717169B
Application number: CN201810654001.6A
Authority: CN
Inventors: 钱正洪; 白茹
Original assignee: Individual
Current assignee: Individual
Priority date: 2018-06-22
Filing date: 2018-06-22
Publication date: 2020-10-09
Anticipated expiration: 2038-06-22
Also published as: CN108717169A

Abstract

The invention relates to a two-dimensional magnetic field sensor. The invention includes a flux guide. The magnetic flux guider is arranged on the substrate, an outer frame of the magnetic flux guider is in an annular or semi-annular structure, and the magnetic flux guider is divided into two or four areas according to a symmetry axis; each area is provided with a magneto-resistor placing gap. Each area is provided with a pair of magnetoresistors, the magnetoresistors are all arranged on the substrate, one magnetoresistor is covered by the magnetic flux guider, and the other magnetoresistor is arranged in the magnetoresistor placing gap. Two pairs of magnetoresistors in two regions at opposite angles are respectively connected into two groups of Wheatstone bridge structures. The invention is single-core integration and has high integration level. The magneto-resistor in the gap of the magnetic flux guider and the magneto-resistor covered by the magnetic flux guider form two groups of Wheatstone bridge structures to form differential output, compared with the traditional two-dimensional magnetic field sensor, the two-dimensional magnetic field sensor has higher precision, strong anti-interference capability, and is easier to miniaturize and integrate, and meanwhile, the double bridges can effectively inhibit temperature drift.

Description

Two-dimensional magnetic field sensor

Technical Field

The invention belongs to the field of magnetic sensors, and relates to a two-dimensional magnetic field sensor.

Background

The prior magnetic field sensor is gradually developed along with the progress of a magnetic measuring instrument, along with the rapid development of information industry, industrial automation, transportation, power electronic technology, office automation, household appliances, medical instruments and the like and the popularization of electronic computer application, the demand of the magnetic field sensor is continuously increased, along with the development of microelectronic technology, the magnetic field sensor is developed towards miniaturization, integration and intellectualization, and further the performance requirement of the magnetic field sensor is also continuously improved.

The existing sensor capable of measuring a two-dimensional magnetic field mainly obtains the magnetic field intensity of two dimensions by installing two orthogonal magnetic sensors on a measuring plane; patent No. 02147304.8 describes a two-dimensional magnetic sensor comprising a first MI element arranged to detect a first axial component of an external magnetic field, a second MI element arranged to detect a second axial component of the external magnetic field, and an integrated circuit; the magnetic field sensor brings errors to a measuring system, occupies a large space, and is not beneficial to integration because two chips need to be packaged. Yet another method of measuring a two-dimensional magnetic field is by two magnetic tunnel junction sensors, wherein a first magnetic tunnel junction sensor includes a first pinned layer and a first sensing element formed on the first pinned layer, and a second magnetic tunnel junction sensor includes a second pinned layer and a second sensing element formed on the second pinned layer and orthogonal to the first sensing element; the design has the problems of complex process, difficult realization and the like.

Disclosure of Invention

The invention aims to provide a two-dimensional magnetic field sensor aiming at the defects of the prior art.

The invention includes a flux guide. The magnetic flux guider is arranged on the substrate, an outer frame of the magnetic flux guider is of a square ring or circular ring structure, and the magnetic flux guider is divided into four areas by two diagonal lines or two vertical symmetrical axes; each area is provided with a magneto-resistor placing gap. Each area is provided with a pair of magnetoresistors, the magnetoresistors are all arranged on the substrate, one magnetoresistor is covered by the magnetic flux guider, and the other magnetoresistor is arranged in the magnetoresistor placing gap.

Two pairs of magnetoresistors in two regions at opposite angles are respectively connected into two groups of Wheatstone bridge structures.

The outer frame of the magnetic flux guider can also be in a semi-annular structure which is symmetrical in the horizontal direction or the vertical direction, and the symmetrical shaft divides the magnetic flux guider into two areas; each area is provided with a magneto-resistor placing gap. Each area is provided with a pair of magnetoresistors, the magnetoresistors are all arranged on the substrate, one magnetoresistor is covered by the magnetic flux guider, and the other magnetoresistor is arranged in the magnetoresistor placing gap. A pair of magnetoresistors in the same region are connected in a half-bridge Wheatstone bridge configuration.

The two sides of the magneto-resistor placing gap and the trimming edge form an inclination angle which is more than 0 degree and less than 90 degrees;

the magnetic flux guider induces a plane magnetic field to pass through two gaps or four gaps of the magnetic flux guider, the magneto-resistor in the gap senses the magnetic field component passing through the gaps, the magneto-resistor changes along with an external field, the magneto-resistor covered by the magnetic flux guider is shielded by soft magnetism, so the magneto-resistor does not change along with the external field, and the magneto-resistor in the gap of the magnetic flux guider and the magneto-resistor covered by the magnetic flux guider form two pairs of Wheatstone bridges to form differential output, thereby realizing the measurement of a two-dimensional magnetic field.

The magneto-resistor is made of the same material and is anisotropic magneto-resistance, giant magneto-resistance and magnetic tunnel junction resistance.

In the same region, the inclination angle of the magneto-resistor is the same as that of the gap for placing the magneto-resistor, and the two sides of the magneto-resistor are parallel to the trimming edge of the gap.

The magnetic flux guider is made of soft magnetic materials.

The invention is a design on a silicon chip level, can be realized by structural design on a preparation process, is single-core integration and has high integration level. The magneto-resistor in the gap of the magnetic flux guider and the magneto-resistor covered by the magnetic flux guider form two groups of Wheatstone bridge structures to form differential output, compared with the traditional two-dimensional magnetic field sensor, the two-dimensional magnetic field sensor has higher precision, strong anti-interference capability and easier miniaturization and integration, and simultaneously, the design can effectively inhibit temperature drift due to the two groups of bridge structures.

Drawings

FIG. 1 is a schematic view of an overall structure of the present invention;

FIG. 2 is another overall structure diagram of the present invention;

FIG. 3 is a schematic view of the overall structure of embodiment 1 of the present invention;

FIG. 4 is a schematic view of the overall structure of embodiment 2 of the present invention;

FIG. 5 is a diagram of a bridge connection according to an embodiment of the present invention;

fig. 6 is a magnetic field decomposition simulation diagram according to embodiment 1 of the present invention.

Detailed Description

The invention is further described below with reference to the accompanying drawings.

As shown in fig. 1 and 2, a two-dimensional magnetic field sensor includes a magnetic flux guide 1. The magnetic flux guider 1 is arranged on the substrate, the outer frame of the magnetic flux guider 1 is of a square ring or circular ring structure, and the magnetic flux guider is divided into four areas by two diagonal lines or two vertical symmetrical axes; each area is provided with the same magneto-resistor placing gap 2. Each zone is provided with a pair of magnetoresistors 3, both arranged on the substrate, one of which is covered by the flux guide and the other of which is arranged in the space where the magnetoresistors are placed.

Wherein, the two sides of the magneto-resistor placing gaps 2 on the four areas and the trimming edge form an inclination angle which is more than 0 degree and less than 90 degrees, and the four magneto-resistor placing gaps 2 are mutually symmetrically or asymmetrically configured; the two sides of the magneto-resistor placing gap 2 on the magnetic flux guider are cut into inclined angles which are larger than 0 degree and smaller than 90 degrees. When the four magneto-resistor placing gaps 2 are symmetrical about two diagonal lines or two vertical symmetrical axes of the magnetic flux guider 1 and the inclination angle is 45 degrees, the performance of the two-dimensional magnetic field sensor is optimal; the magnetoresistors placed in each gap of the flux guide 1 are parallel or at an angle to the cut edges of the gap.

As shown in fig. 3, in the first embodiment, the magnetic flux guide 1 is square ring-shaped, each side is provided with a space 2 for placing the magnetoresistor, two sides of which form an inclination angle of 45 degrees with the cut edge, and the four spaces 2 for placing the magnetoresistor are symmetrical with respect to two diagonals of the magnetic flux guide 1.

The magnetoresistors placed in the magnetoresistor placing gaps 2 are parallel to the gap trimming edges, and the magnetoresistors covered by the magnetic flux guider 1 are arranged beside the magnetoresistors placed in the magnetoresistor placing gaps 2; the magnetic flux guide is made of a soft magnetic material with high magnetic permeability, such as nickel iron, iron-silicon alloy (silicon steel sheet), and the like.

As shown in fig. 4, the magnetic flux guide 1 of the second embodiment is a square ring shape having two mutually perpendicular sides. The structure of each side is the same as in embodiment 1.

In example 1, two sets of four magnetic resistances at opposite sides of the magnetic flux guide 1 are respectively formed into two wheatstone bridges. The two Wheatstone bridges have the same structure, the resistor in the space for placing the magneto-resistor on one side is a first magneto-resistive resistor R1, and the other resistor is a second magneto-resistive resistor R2; the resistance in the space between the magnetoresistors on the other side is the third magnetoresistive resistor R3, and the other resistance is the fourth magnetoresistive resistor R4.

As shown in fig. 5, one end of the first magnetoresistive resistor R1 is connected to one end of the second magnetoresistive resistor R2 and then connected to a VCC input power supply; one end of the third magnetoresistive resistor R3 is connected with one end of the fourth magnetoresistive resistor R4 and then grounded; the other end of the first reluctance resistor R1 is connected with the other end of the fourth reluctance resistor R4 to serve as a first output end, and the other end of the third reluctance resistor R3 is connected with the other end of the second reluctance resistor R2 to serve as a second output end; the two output terminals of each wheatstone bridge form differential outputs Vout1 and Vout2, respectively.

As shown in fig. 6, the in-plane magnetic field measured by the sensor is decomposed into magnetic flux components in both the X-axis and Y-axis directions by the flux guide.

The working principle is that because the high magnetic permeability characteristic of the magnetic flux guider is induced to pass through the gap along the inside of the magnetic flux guider, the magneto-resistor in the gap can sense the magnetic field component passing through the gap, the magneto-resistor changes along with an external field, and the magneto-resistor covered by the magnetic flux guider is shielded by soft magnetic, so the magneto-resistor does not change along with the external field, and two differential outputs are respectively obtained by two groups of electric bridges, thereby realizing the measurement of the magnetic field intensity of a two-dimensional magnetic field.

It will be evident to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, and that the present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. Any reference sign in a claim should not be construed as limiting the claim concerned.

Claims

1. A two-dimensional magnetic field sensor comprising a magnetic flux guide; the method is characterized in that: the outer frame of the magnetic flux guider is in a semi-annular structure which is symmetrical along a diagonal line in the horizontal direction or the vertical direction, and a symmetry axis divides the magnetic flux guider into two areas; each area is provided with a magneto-resistor placing gap; each area is provided with a pair of magnetoresistors, the magnetoresistors are all arranged on the substrate, one magnetoresistor is covered by the magnetic flux guider, and the other magnetoresistor is arranged in a magnetoresistor placing gap; a pair of magnetoresistors in the same area are connected into a half-bridge Wheatstone bridge structure; in the same region, the inclination angle of the magneto-resistor is the same as that of the magneto-resistor placing gap, and the two sides of the magneto-resistor are parallel to the trimming edge of the gap; the flux guide is a single core integration.

2. The two-dimensional magnetic field sensor of claim 1, wherein: and the two sides of the magneto-resistor placing gap and the trimming edge form an inclination angle which is more than 0 degree and less than 90 degrees.

3. The two-dimensional magnetic field sensor of claim 1, wherein: the magnetic flux guider induces a plane magnetic field to pass through two gaps of the magnetic flux guider, the magnetoresistors in the gaps sense the magnetic field components passing through the gaps, the magnetoresistors change along with an external field, the magnetoresistors covered by the magnetic flux guider are shielded by soft magnetism, so the magnetoresistors do not change along with the external field, and the magnetoresistors in the gaps of the magnetic flux guider and the magnetoresistors covered by the magnetic flux guider form two pairs of Wheatstone bridges to form differential output, so that the measurement of a two-dimensional magnetic field is realized.

4. The two-dimensional magnetic field sensor of claim 1, wherein: the magneto-resistor is made of the same material and is anisotropic magneto-resistance, giant magneto-resistance and magnetic tunnel junction resistance.

5. The two-dimensional magnetic field sensor of claim 1, wherein: the magnetic flux guider is made of soft magnetic materials.