JP2017181403A - Magnetic sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic sensor for detecting an external magnetic field.SOLUTION: A magnetic sensor comprises: a first magnetic resistance element; and a magnetic field generation device which generates a bias magnetic field and applies the bias magnetic field to the first magnetic resistance element, thereby changing the state of the first magnetic resistance element from a first state having predetermined magnetic sensitivity to a second state having magnetic sensitivity different from the first state. The magnetic sensitivity of the first magnetic resistance element in the first state may be larger than the magnetic sensitivity of the first magnetic resistance element in the second state.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a magnetic sensor.

Conventionally, in a magnetic sensor that detects an external magnetic field, it is known to reduce variations by using two magnetoresistive elements that change in opposite directions according to the external magnetic field (see, for example, Patent Document 1).
Patent Document 1 Japanese Patent Application Laid-Open No. 2006-105693

  However, the conventional magnetic sensor cannot remove the offset due to the mismatch of the resistance values of the two magnetoresistive elements.

  In the first aspect of the present invention, the state of the first magnetoresistive element is predetermined by generating a bias magnetic field with the first magnetoresistive element and applying the bias magnetic field to the first magnetoresistive element. Provided is a magnetic sensor including a magnetic field generator that changes from a first state having magnetic sensitivity to a second state having a magnetic sensitivity different from that of the first state.

  It should be noted that the above summary of the invention does not enumerate all the necessary features of the present invention. In addition, a sub-combination of these feature groups can also be an invention.

The 1st state of the magnetic sensor 100 which concerns on Example 1 is shown. 2 shows a second state of the magnetic sensor 100 according to the first embodiment. An example of sectional drawing of magnetic sensor 100 concerning Example 1 is shown. An example of the magnetoresistive characteristic of the magnetoresistive element 10 is shown. An example of a configuration of the magnetic sensor 100 according to the second embodiment is shown. An example of sectional drawing of the magnetic sensor 100 which concerns on Example 2 is shown. An example of the structure of the magnetic sensor 100 which concerns on Example 3 is shown. An example of the top view of the magnetic sensor 100 which concerns on Example 4 is shown. An example of sectional drawing of magnetic sensor 100 concerning Example 4 is shown. The magnetic simulation result of the magnetic sensor 100 which concerns on Example 4 is shown. 10 shows an exemplary configuration of a magnetic sensor 100 according to a fifth embodiment. An outline of the configuration of the control system 300 is shown.

  Hereinafter, the present invention will be described through embodiments of the invention, but the following embodiments do not limit the invention according to the claims. In addition, not all the combinations of features described in the embodiments are essential for the solving means of the invention.

[Example 1]
FIG. 1 shows a first state of the magnetic sensor 100 according to the first embodiment. FIG. 2 shows a second state of the magnetic sensor 100 according to the first embodiment.

  The magnetic sensor 100 of this example includes a magnetoresistive element 10 and a magnetic field generator 20. The magnetoresistive element 10 includes a first magnetoresistive element 11 and a second magnetoresistive element 12.

  In this specification, three directions perpendicular to the first direction to the third direction are indicated by X, Y, and Z axes. FIG. 1 shows a plan view of the magnetic sensor 100 in the XY plane (plan view seen from the Z-axis direction). That is, FIG. 1 shows an example of a top view when the magnetic sensor 100 is formed on one surface of a substrate or the like.

  The resistance of the first magnetoresistive element 11 changes according to the input magnetic field. The first magnetoresistive element 11 is formed by extending in the Y-axis direction. The first magnetoresistive element 11 of this example has a shape symmetric with respect to the central axis c1 in plan view. The first magnetoresistive element 11 is formed on the XY plane. The first magnetoresistive element 11 has a magnetosensitive axis in the X-axis direction.

  The resistance of the second magnetoresistive element 12 changes according to the input magnetic field. The second magnetoresistive element 12 is formed by extending in the Y-axis direction. The second magnetoresistive element 12 of this example has a shape symmetric with respect to the central axis c2 in plan view. The second magnetoresistive element 12 is formed on the XY plane. The second magnetoresistive element 12 has a magnetosensitive axis in the X-axis direction. That is, the second magnetoresistive element 12 has a magnetosensitive axis parallel to the magnetosensitive axis of the first magnetoresistive element 11.

  The first magnetoresistive element 11 and the second magnetoresistive element 12 are formed symmetrically with respect to the symmetry axis s. The 1st magnetoresistive element 11 and the 2nd magnetoresistive element 12 are arrange | positioned at intervals d1 between each center axis | shaft c1, c2. The distance d1 between the central axes c1 and c2 is set to a value at least larger than zero.

  It is preferable that the 1st magnetoresistive element 11 and the 2nd magnetoresistive element 12 are flat form. The shapes of the first magnetoresistive element 11 and the second magnetoresistive element 12 in this example are rectangular. However, the shape of the first magnetoresistive element 11 and the second magnetoresistive element 12 is not limited to a rectangle, and may be any shape, for example, a square, a square, a parallelogram, a trapezoid, a triangle, a circle, It may be oval.

  The magnetoresistive element 10 changes its resistance value by sensing a uniaxial magnetic field. In one example, the magnetoresistive element 10 is a giant magnetoresistive (GMR) element that detects magnetism in one predetermined direction. The magnetoresistive element 10 is not limited to a GMR element, but may be any element that changes the resistance value by sensing only a magnetic field in one axis direction. That is, the magnetoresistive element 10 may be a tunnel magnetoresistive (TMR) element or an anisotropic magnetoresistive (AMR: Anisotropy-Magneto-Resistive) element.

  The first magnetoresistive element 11 may have a plurality of magnetoresistive elements. That is, the first magnetoresistive element 11 is not limited to being configured with one magnetoresistive element, and may be formed by connecting two or more magnetoresistive elements with metal wiring. For example, the first magnetoresistive element 11 is composed of a plurality of magnetoresistive elements arranged in a line in the Y-axis direction. The first magnetoresistive element 11 may be composed of a plurality of magnetoresistive elements arranged in the Y-axis direction so as to form a plurality of columns. However, it is preferable that the magnetosensitive axes of the plurality of magnetoresistive elements included in the first magnetoresistive element 11 coincide. Similarly to the first magnetoresistive element 11, the second magnetoresistive element 12 may include a plurality of magnetoresistive elements.

Magnetic field generator 20 generates a bias magnetic field _{B V.} The magnetic field generator 20 applies the generated bias magnetic field _BV to the first magnetoresistive element 11 and the second magnetoresistive element 12. Magnetic field generator 20 generates a bias magnetic field B _V, modulates the magnetic sensitivity of the first magnetoresistance element 11 and the second magnetoresistance element 12. Modulating the magnetic sensitivity refers to setting the state of the magnetoresistive element 10 from the first state to the second state by applying the bias magnetic field _BV to the magnetoresistive element 10.

  The first state and the second state indicate states in which the magnetic sensitivities of the first magnetoresistive element 11 and the second magnetoresistive element 12 are different from each other.

The first state refers to the state of the magnetic sensitivity of the magnetic resistance element 10 when the magnetic field generator 20 is not generating a bias magnetic field B _V. In this specification, the first state is referred to as a no-bias state.

The second condition refers to a condition of the magnetic sensitivity of the magnetic resistance element 10 when the magnetic field generator 20 is generating a bias magnetic field B _V. In this specification, the second state is referred to as a bias magnetic field. However, the first state and the second state may be in the bias state as long as the magnitude of the magnetic sensitivity of the magnetoresistive element 10 in the first state and the second state is different.

The magnetic field generator 20 is disposed in the vicinity of the magnetoresistive element 10. The vicinity of the magnetoresistive element 10, in one example, refers to the distance to the extent that the bias magnetic field B _V generated magnetic field generating device 20 can be applied to the magnetoresistive element 10. The magnetic field generator 20 is formed to extend parallel to the magnetosensitive axis of the magnetoresistive element 10. The magnetic field generator 20 of this example is disposed so as to overlap and cross the first magnetoresistive element 11 and the second magnetoresistive element 12. Thereby, the magnetic field generator 20 gives the bias magnetic field _BV to the first magnetoresistive element 11 and the second magnetoresistive element 12. However, the magnetic field generator 20 may be formed apart from the first magnetoresistive element 11 and the second magnetoresistive element 12 in plan view. Magnetic field generating device 20, the first magnetoresistance element 11 and the second magnetoresistance element 12, may provide a biasing magnetic field B _V of different sizes, but the magnetic field generating apparatus 20 of the present embodiment, the first magnetoresistive A bias magnetic field B _V having the same strength is applied to the element 11 and the second magnetoresistive element 12.

Magnetic field generator 20 generates a bias magnetic field B _V having at least a magnetic sensing axis and a direction different from the components of the first magnetoresistance element 11. Magnetic field generating device 20, the magnetic sensing axis perpendicular component of the first magnetoresistance element 11 may generate a bias magnetic field B _V which has at least. Further, in one example, the magnetic field generator 20 generates a magnetic sensing axis perpendicular bias field B _V of the first magnetoresistance element 11.

  FIG. 3 illustrates an example of a cross-sectional view of the magnetic sensor 100 according to the first embodiment. The magnetic sensor 100 includes a substrate 40 and an insulating layer 42.

  The substrate 40 may be any of a silicon substrate, a compound semiconductor substrate, a ceramic substrate, and the like. The substrate 40 may be a substrate on which an electronic circuit such as an IC is mounted. An insulating layer 42 and the like are formed on the substrate plane 50 of the substrate 40. The upper surface of the insulating layer 42 is formed as a surface substantially parallel to the XY plane, and is a second plane 52 in this example.

  The first magnetoresistive element 11 and the second magnetoresistive element 12 are formed on the first plane 51. The first plane 51 may be a virtual plane in the insulating layer 42. The first plane 51 is formed as a plane substantially parallel to the XY plane.

  The magnetic field generator 20 is formed on the second plane 52 so that the metal wiring extending in the X-axis direction overlaps and crosses the first magnetoresistive element 11 and the second magnetoresistive element 12 in the cross-sectional view. The first plane 51 and the second plane 52 are substantially parallel and are arranged so as not to overlap each other. Although the magnetic field generator 20 of this example is drawn with one metal wiring, it may be composed of a plurality of metal wirings arranged in the Y-axis direction on the second plane 52.

Magnetic field generating device 20 can be composed of a plurality of metal wires, it can be given a uniform bias magnetic field B _V to the first magnetoresistance element 11 and the second magnetoresistance element 12. When the magnetic field generator 20 has a plurality of metal wirings, each of them may be connected in parallel to pass a current in the same direction. Moreover, each of the plurality of metal wirings may be connected in series.

  The magnetic field generator 20 is preferably formed of a metal having a low specific resistance from the viewpoint of power loss. In one example, the magnetic field generator 20 is formed of copper, gold, platinum, aluminum, or an alloy including these materials.

Here, consider a case where a magnet is arranged on the X-axis negative side of the magnetic sensor 100. In this case, a magnetic field B in the X-axis direction is input to the magnetoresistive element 10. In this example, magnetic fields B ₁ and B ₂ in the X-axis direction are input to the first magnetoresistive element 11 and the second magnetoresistive element 12, respectively. The magnetic fields B ₁ and B _{2 in the} X-axis direction are not uniform, for example, B ₁ > B ₂ .

Respective resistance values R ₁ and R ₂ of the first magnetoresistive element 11 and the second magnetoresistive element 12 are expressed by the following equations.
(Formula 1)
R ₁ = ΔR ₁ · B ₁ + R ₀₁
(Formula 2)
R ₂ = ΔR ₂ · B ₂ + R ₀₂

R ₀₁ and R ₀₂ indicate initial resistance values of the first magnetoresistive element 11 and the second magnetoresistive element 12, respectively. In this specification, the initial resistance value refers to the resistance value of the magnetoresistive element 10 when there is no input magnetic field in the X-axis direction. ΔR ₁ and ΔR ₂ are the magnetic sensitivities of the first magnetoresistive element 11 and the second magnetoresistive element 12 in the X-axis direction. B ₁ and B ₂ are magnetic fields in the X-axis direction applied to the first magnetoresistive element 11 and the second magnetoresistive element 12.

The magnetic sensor 100 includes a calculation unit described later, and detects the difference between the resistance value of the first magnetoresistive element 11 and the resistance value of the second magnetoresistive element 12.
(Formula 3)
R ₁ −R ₂ = (ΔR ₁ B ₁ −ΔR ₂ B ₂ ) + (R ₀₁ −R ₀₂ )

(ΔR ₁ B ₁ −ΔR ₂ B ₂ ) is a difference in resistance value that reacts to the input magnetic fields B ₁ and B ₂ in the X-axis direction. (R ₀₁ −R ₀₂ ) is a difference between the initial resistance values of the first magnetoresistive element 11 and the second magnetoresistive element 12 (that is, if the two initial resistance values are not aligned, the difference value is an offset).

In the non-bias state, the resistance values R _1N and R _2N of the first magnetoresistive element 11 and the second magnetoresistive element 12 are expressed by the following equations.
(Formula 4)
R _1N = ΔR ₁ · B ₁ + R ₀₁
(Formula 5)
R _2N = ΔR ₂ · B ₂ + R ₀₂

On the other hand, in the bias state, the magnetic sensitivity of the first magnetoresistance element 11 and the second magnetoresistance element 12, the magnetic sensitivity [Delta] R ₁ under no bias state, ₁ × _a respectively [Delta] R _2, changes _{twice a.} The initial resistance value in the bias state changes to b ₁ times and b ₂ times the initial resistance values R ₀₁ and R ₀₂ of the first magnetoresistive element 11 and the second magnetoresistive element 12 in the non-bias state, respectively. . Therefore, in the bias state, the resistance values R _1B and R _2B of the first magnetoresistive element 11 and the second magnetoresistive element 12 are expressed by the following equations.
(Formula 6)
R _1B = (a ₁ ΔR ₁ ) B ₁ + b ₁ R ₀₁
(Formula 7)
R _2B = (a ₂ ΔR ₂ ) B ₂ + b ₂ R ₀₂

b ₁ R ₀₁ and b ₂ R ₀₂ indicate initial resistance values of the first magnetoresistive element 11 and the second magnetoresistive element 12. a ₁ ΔR ₁ and a ₂ ΔR ₂ are the magnetic sensitivities of the first magnetoresistive element 11 and the second magnetoresistive element 12 in the bias state.

The difference between the resistance values of the first magnetoresistive element 11 and the second magnetoresistive element 12 is expressed by the following equation.
(Formula 8)
R _1N −R _2N = (ΔR ₁ B ₁ −ΔR ₂ B ₂ ) + (R ₀₁ −R ₀₂ )
(Formula 9)
R _1B −R _2B = (a ₁ ΔR ₁ B ₁ −a ₂ ΔR ₂ B ₂ ) + (b ₁ R ₀₁ −b ₂ R ₀₂ )

(ΔR ₁ B ₁ −ΔR ₂ B ₂ ) is a difference in resistance value according to the input magnetic field in a no-bias state. (R ₀₁ -R ₀₂ ) is an offset in a no-bias state. On the other hand, (a ₁ ΔR ₁ B ₁ −a ₂ ΔR ₂ B ₂ ) is a difference in resistance value according to the input magnetic field in the bias state. (B ₁ R ₀₁ -b ₂ R ₀₂ ) is an offset in the bias state.

FIG. 4 shows an example of the magnetoresistive characteristic of the first magnetoresistive element 11. The vertical axis represents the resistance value R [Ω] of the first magnetoresistive element 11, and the horizontal axis represents the magnetic field B _X [mT] applied to the first magnetoresistive element 11. Further, the magnetic field Bx of this example gives a magnetic field having a magnitude of −1.0 mT to +1.0 mT in the X-axis direction to the first magnetoresistive element 11. Further, the magnetoresistive characteristics of this example correspond to the magnetoresistive characteristics of the first magnetoresistive element 11 in the no-bias state and the bias state, respectively. The magnetic field generator 20 of this example generates a magnetic field having a magnitude of 0 mT and +1.0 mT in the Y-axis direction with respect to the first magnetoresistive element 11.

The resistance value R _1N indicates the resistance value of the first magnetoresistive element 11 in the no-bias state. The resistance value R _1B indicates the magnetoresistance characteristic of the first magnetoresistance element 11 in the bias state.

  The initial resistance value of the first magnetoresistance element 11 in the no-bias state may be equal to the initial resistance value of the first magnetoresistance element 11 in the bias state. Here, the initial resistance value is equal is that the difference between the initial resistance values of the first magnetoresistive element 11 in the unbiased state and the biased state is within 1% of the resistance value of the first magnetoresistive element 11 in the unbiased state. It points to something.

On the other hand, in the case of having two magnetoresistive elements of the first magnetoresistive element 11 and the second magnetoresistive element 12 as in the magnetic sensor 100 of the first embodiment, it can be considered similarly to the case of this example. That is, the difference between the initial resistance value of the first magnetoresistive element 11 in the unbiased state and the initial resistance value of the first magnetoresistive element 11 in the biased state (that is, R ₀₁ -b ₁ R ₀₁ ) May be equal to the difference between the initial resistance value of the second magnetoresistive element 12 and the initial resistance value of the second magnetoresistive element 12 in the bias state (ie, R ₀₂ −b ₂ R ₀₂ ).

Here, the difference between (R ₀₁ -b ₁ R ₀₁ ) and (R ₀₂ -b ₂ R ₀₂ ) is equal to (R ₀₁ -b ₁ R ₀₁ ) and (R ₀₂ -b ₂ R ₀₂ ) Is within 1% of the resistance value of the first magnetoresistive element 11 (ie, R ₀₁ ) in the non-biased state or the resistance value of the second magnetoresistive element 12 (ie, R ₀₂ ) in the non-biased state. Point to.

Further, the difference between the initial resistance value of the first magnetoresistive element 11 in the non-biased state and the initial resistance value of the second magnetoresistive element 12 in the non-biased state (that is, R ₀₁ −R ₀₂ ) is the first resistance value in the biased state. The difference between the initial resistance value of the first magnetoresistive element 11 and the initial resistance value of the second magnetoresistive element 12 in the bias state (that is, b ₁ R ₀₁ −b ₂ R ₀₂ ) may be equal.

Here, the difference between (R ₀₁ -R ₀₂ ) and (b ₁ R ₀₁ -b ₂ R ₀₂ ) is equal to (R ₀₁ -R ₀₂ ) and (b ₁ R ₀₁ -b ₂ R ₀₂ ) Is within 1% of the resistance value of the first magnetoresistive element 11 (ie, R ₀₁ ) in the non-biased state or the resistance value of the second magnetoresistive element 12 (ie, R ₀₂ ) in the non-biased state. Point to.

  As described above, even if either the initial resistance value of the first magnetoresistive element 11 in the no-bias state or the bias state and the initial resistance value of the second magnetoresistive element 12 in the no-bias state or the bias state are increased, The offset can be canceled if the difference in the initial resistance value is canceled in the midway calculation. Such a concept holds true even when the number of magnetoresistive elements is increased to three or more.

Further, the magnetic sensitivity of the first magnetoresistive element 11 in the no-bias state is larger than the magnetic sensitivity of the first magnetoresistive element 11 in the biased state. That is, the first magneto-resistive element 11 of this embodiment, by biasing magnetic field B _V is applied, the magnetic sensitivity is reduced.

Resistance values R _1N and R _1B of the first magnetoresistive element 11 are expressed by the following equations.
(Formula 10)
R _1N = ΔR ₁ · B ₁ + R ₀₁
(Formula 11)
R _1B = (a ₁ ΔR ₁ ) B ₁ + b ₁ R ₀₁

Here, since b ₁ = 1.001 and a ₁ = 0.75, the magnetic sensitivity of the first magnetoresistive element 11 is smaller in the biased state than in the non-biased state. On the other hand, since the initial resistance value R ₀₁ ≈b ₁ R ₀₁ (b ₁ = 1.001), the initial resistance value R ₀₁ of the first magnetoresistive element 11 hardly varies between the non-bias state and the bias state.

According to the characteristics of the first magnetoresistive element 11, the offset (R ₀₁ −R ₀₂ ) in equation (8) and the offset (b ₁ R ₀₁ −b ₂ R ₀₂ ) in equation (9) are b ₁ ≈b _Since 2≈1, (R ₀₁ −R ₀₂ ) ≈ (b ₁ R ₀₁ −b ₂ R ₀₂ ). Using this characteristic, the magnetic sensor 100 can cancel the offset between the non-bias state and the bias state. By calculating the difference between Equation (8) and Equation (9), the following equation is obtained.
(Formula 12)
_{(R 1N -R 2N) - (} R 1B -R 2B) = (1-a 1) ΔR 1 B 1 - (1-a 2) ΔR 2 B 2

Therefore, the magnetic sensor 100 can calculate only the resistance component that removes the offset and reacts to the magnetic fields B ₁ and B ₂ in the X-axis direction. Thus, the detection accuracy of the magnetic sensor 100 is improved by removing the offset.

Furthermore, the first magnetoresistive element 11 and the second magnetoresistive element 12 preferably have the same magnetic sensitivity ΔR in the X-axis direction. In this case, ΔR ₁ = ΔR ₂ = ΔR. Further, the characteristics of the first magnetoresistive element 11 and the second magnetoresistive element 12 become substantially equal when formed on the same chip substrate. In this case, a ₁ = a ₂ = a. Therefore, the equation (12) is expressed by the following equation.
(Formula 13)
_{(R 1N -R 2N) - (} R 1B -R 2B) = (1-a) ΔR (B 1 -B 2)

[Example 2]
FIG. 5 shows an example of the configuration of the magnetic sensor 100 according to the second embodiment. FIG. 6 illustrates an example of a cross-sectional view of the magnetic sensor 100 according to the second embodiment. The magnetic sensor 100 of this example includes a first magnetoresistive element 11, a second magnetoresistive element 12, a third magnetoresistive element 13, and a fourth magnetoresistive element 14 as the magnetoresistive element 10. In this example, differences from the magnetic sensor 100 according to the first embodiment will be mainly described.

  The resistance of the third magnetoresistive element 13 changes according to the input magnetic field. The third magnetoresistive element 13 is formed by extending in the Y-axis direction. The third magnetoresistive element 13 of this example has a shape symmetrical to the central axis c3 in plan view. The third magnetoresistive element 13 is formed on the XY plane. The third magnetoresistive element 13 has a magnetosensitive axis in the X-axis direction. That is, the third magnetoresistive element 13 has a magnetosensitive axis parallel to the magnetosensitive axis of the first magnetoresistive element 11.

  The resistance of the fourth magnetoresistive element 14 changes according to the input magnetic field. The fourth magnetoresistive element 14 is formed by extending in the Y-axis direction. The fourth magnetoresistive element 14 of this example has a shape symmetric with respect to the central axis c4 in plan view. The fourth magnetoresistive element 14 is formed on the XY plane. The fourth magnetoresistive element 14 has a magnetosensitive axis in the X-axis direction. That is, the fourth magnetoresistive element 14 has a magnetosensitive axis parallel to the magnetosensitive axis of the first magnetoresistive element 11.

  The 1st magnetoresistive element 11 and the 2nd magnetoresistive element 12 are arrange | positioned at intervals d1 between each center axis | shaft c1, c2. The distance d1 between the central axes c1 and c2 is set to a value at least larger than zero.

  The 3rd magnetoresistive element 13 and the 4th magnetoresistive element 14 are arrange | positioned at intervals d2 between each center axis | shaft c3, c4. The distance d2 between the central axes c3 and c4 is set to a value at least larger than zero.

  The third magnetoresistive element 13 and the fourth magnetoresistive element 14 are on an axis in the Y-axis direction on the first plane 51 excluding the intermediate axis m of the interval between the first magnetoresistive element 11 and the second magnetoresistive element 12. It is provided so as to be symmetrical. In the present specification, the intermediate axis m of the first magnetoresistive element 11 and the second magnetoresistive element 12 is located between the central axis c1 of the first magnetoresistive element 11 and the central axis c2 of the second magnetoresistive element 12. An axis parallel to the Y axis.

  The 3rd magnetoresistive element 13 and the 4th magnetoresistive element 14 are arrange | positioned so that the space | interval d2 may become equal to the space | interval d1 (d1 = d2). That is, when considering the differential configuration, it is preferable that the first magnetoresistive element 11 and the second magnetoresistive element 12 having the same interval form a pair, and the third magnetoresistive element 13 and the fourth magnetoresistive element 14 form a pair. .

  The first magnetoresistive element 11 and the third magnetoresistive element 13 are arranged symmetrically with respect to the symmetry axis s. Further, the second magnetoresistive element 12 and the fourth magnetoresistive element 14 are arranged symmetrically with respect to the symmetry axis s.

  The first magnetoresistive element 11 is formed between the third magnetoresistive element 13 and the fourth magnetoresistive element 14. The third magnetoresistive element 13 is formed between the first magnetoresistive element 11 and the second magnetoresistive element 12. That is, in this example, the pair of the first magnetoresistive element 11 and the second magnetoresistive element 12 having the differential configuration and the pair of the third magnetoresistive element 13 and the fourth magnetoresistive element 14 are arranged alternately. Has been.

The magnetic field generator 20 is disposed so as to overlap and cross the first magnetoresistive element 11 to the fourth magnetoresistive element 14. Magnetic field generator 20 applies a bias magnetic field _{B V} of the Y-axis direction with respect to the first magneto-resistive element 11 to the fourth magnetoresistance element 14. For example, the magnetic field generator 20 is formed on the XY plane so that the metal wiring extending in the X-axis direction overlaps and crosses the first magnetoresistive element 11 to the fourth magnetoresistive element 14. In the present specification, the first to fourth magnetoresistive elements 11 to 14 are the first magnetoresistive element 11, the second magnetoresistive element 12, the third magnetoresistive element 13, and the fourth magnetoresistive element 14. Point to.

[Example 3]
FIG. 7 illustrates an example of the configuration of the magnetic sensor 100 according to the third embodiment. The magnetic sensor 100 of this example has four magnetoresistive elements, that is, a first magnetoresistive element 11 to a fourth magnetoresistive element 14 as the magnetoresistive element 10. The magnetic sensor 100 of this example differs from the magnetic sensor 100 according to the second embodiment in the arrangement order of the magnetoresistive elements.

  The intermediate axis m ′ of the third magnetoresistive element 13 and the fourth magnetoresistive element 14 is disposed outside the region sandwiched between the first magnetoresistive element 11 and the second magnetoresistive element 12. In this specification, the intermediate axis m ′ of the third magnetoresistive element 13 and the fourth magnetoresistive element 14 is positioned between the central axis c3 of the third magnetoresistive element 13 and the central axis c4 of the fourth magnetoresistive element 14. An axis parallel to the Y axis.

  The first magnetoresistive element 11 and the second magnetoresistive element 12 are formed on the opposite side of the third magnetoresistive element 13 and the fourth magnetoresistive element 14 with the axis of symmetry s interposed therebetween. That is, the magnetic sensor 100 according to the second embodiment includes a pair of the first magnetoresistive element 11 and the second magnetoresistive element 12 and a pair of the third magnetoresistive element 13 and the fourth magnetoresistive element 14 that have a differential configuration. They are arranged in a staggered manner. On the other hand, in the magnetic sensor 100 of this example, the pair of the first magnetoresistive element 11 and the second magnetoresistive element 12 and the pair of the third magnetoresistive element 13 and the fourth magnetoresistive element 14 having a differential configuration are staggered. Instead, they are arranged on one side of the symmetry axis s.

Magnetic fields B ₁ , B ₂ , B ₃ , and B ₄ in the X-axis direction are input to each of the first magnetoresistive element 11 to the fourth magnetoresistive element 14. The magnetic fields B ₁ , B ₂ , B ₃ , and B ₄ in the X-axis direction are not uniform, and for example, B ₁ > B ₂ and B ₃ > B ₄ . R ₁ , R ₂ , R ₃ , and R ₄ are resistance values of the first to fourth magnetoresistive elements 11 to 14, respectively, and are represented by the following equations.
(Formula 14)
R ₁ = R ₀₁ + ΔR ₁ · B ₁
(Formula 15)
R ₂ = R ₀₂ + ΔR ₂ · B ₂
(Formula 16)
R ₃ = R ₀₃ + ΔR ₃ · B ₃
(Formula 17)
R ₄ = R ₀₄ + ΔR ₄ · B ₄

R ₀₁ , R ₀₂ , R ₀₃ , and R ₀₄ indicate initial resistance values of the first magnetoresistive element 11 to the fourth magnetoresistive element 14. ΔR ₁ , ΔR ₂ , ΔR ₃ , ΔR ₄ indicate the magnetic sensitivities of the first magnetoresistive element 11 to the fourth magnetoresistive element 14. B ₁ , B ₂ , B ₃ , and B ₄ are magnetic fields in the X-axis direction that are input to the first magnetoresistive element 11 to the fourth magnetoresistive element 14. Here, the difference between the resistance values of the first magnetoresistance element 11 and the second magnetoresistance element 12 and the difference between the resistance values of the fourth magnetoresistance element 14 and the third magnetoresistance element 13 are respectively expressed by the following equations. .
(Formula 18)
R ₁ −R ₂ = (ΔR ₁ B ₁ −ΔR ₂ B ₂ ) + (R ₀₁ −R ₀₂ )
(Formula 19)
R ₃ −R ₄ = (ΔR ₃ B ₃ −ΔR ₄ B ₄ ) + (R ₀₃ −R ₀₄ )

(ΔR ₁ B ₁ −ΔR ₂ B ₂ ) indicates a difference in resistance value due to the input magnetic field of the first magnetoresistive element 11 and the second magnetoresistive element 12. (R ₀₁ -R ₀₂ ) is an offset between the first magnetoresistive element 11 and the second magnetoresistive element 12. Further, (ΔR ₃ B ₃ −ΔR ₄ B ₄ ) indicates a difference in resistance value due to the input magnetic field of the third magnetoresistive element 13 and the fourth magnetoresistive element 14. (R ₀₃ -R ₀₄ ) is an offset between the fourth magnetoresistive element 14 and the third magnetoresistive element 13.

In the magnetic sensor 100 of this example, the arithmetic unit calculates the difference between the resistance values of the first magnetoresistive element 11 and the second magnetoresistive element 12 and the difference between the resistance values of the fourth magnetoresistive element 14 and the third magnetoresistive element 13. And the sum of.
(Formula 20)
(R ₁ −R ₂ ) + (R ₃ −R ₄ )
= [(ΔR ₁ B ₁ −ΔR ₂ B ₂ ) + (ΔR ₃ B ₃ −ΔR ₄ B ₄ )]
+ [(R ₀₁ -R ₀₂ ) + (R ₀₃ -R ₀₄ )]

In the above equation, [(R ₀₁ −R ₀₂ ) + (R ₀₃ −R ₀₄ )] is the offset of the first magnetoresistive element 11 and the second magnetoresistive element 12, and the fourth magnetoresistive element 14 and the third magnetism. This is the sum of the offset of the resistance element 13.

  Next, the difference between the resistance values of the first magnetoresistance element 11 and the second magnetoresistance element 12 and the difference between the resistance values of the fourth magnetoresistance element 14 and the third magnetoresistance element 13 will be considered.

The difference between the resistance values of the first magnetoresistive element 11 and the second magnetoresistive element 12 is expressed by the following equation in the non-bias state.
(Formula 21)
R _1N −R _2N = (ΔR ₁ B ₁ −ΔR ₂ B ₂ ) + (R ₀₁ −R ₀₂ )
(ΔR ₁ B ₁ −ΔR ₂ B ₂ ) indicates a difference in resistance value due to the input magnetic field. (R ₀₁ -R ₀₂ ) indicates an offset.

The difference between the resistance values of the first magnetoresistive element 11 and the second magnetoresistive element 12 is expressed by the following equation in the bias state. In bias state, the magnetic sensitivity of the first magnetoresistance element 11 and the second magnetoresistance element 12, the magnetic sensitivity [Delta] R ₁ under no bias state, ₁ × _a respectively [Delta] R _2, changes _{twice a.} The initial resistance value in the bias state changes to b ₁ times and b ₂ times the initial resistance values R ₀₁ and R ₀₂ of the first magnetoresistive element 11 and the second magnetoresistive element 12 in the non-bias state, respectively. .
(Formula 22)
R _1B −R _2B = (a ₁ ΔR ₁ B ₁ −a ₂ ΔR ₂ B ₂ ) + (b ₁ R ₀₁ −b ₂ R ₀₂ )
(A ₁ ΔR ₁ B ₁ −a ₂ ΔR ₂ B ₂ ) indicates a difference in resistance value due to an input magnetic field. (B ₁ R ₀₁ -b ₂ R ₀₂ ) indicates an offset.

Further, the difference between the resistance values of the fourth magnetoresistive element 14 and the third magnetoresistive element 13 is expressed by the following equation in the non-bias state.
(Formula 23)
R _3N −R _4N = (ΔR ₃ B ₃ −ΔR ₄ B ₄ ) + (R ₀₃ −R ₀₄ )
(ΔR ₃ B ₃ −ΔR ₄ B ₄ ) indicates a difference in resistance value due to the input magnetic field. (R ₀₃ -R ₀₄ ) indicates an offset.

The difference between the resistance values of the fourth magnetoresistive element 14 and the third magnetoresistive element 13 is expressed by the following equation in the bias state. In bias state, the magnetic sensitivity of the fourth magnetoresistive element 14 and the third magnetoresistance element 13, the magnetic sensitivity [Delta] R ₄ under no bias state, _{a 4-fold} respectively [Delta] R _3, changes to _{a 3-fold.} Further, the initial resistance value in the bias state changes to b ₄ times and b ₃ times the initial resistance values R ₀₄ and R ₀₃ of the fourth magnetoresistive element 14 and the third magnetoresistive element 13 in the non-bias state, respectively. .
(Formula 24)
R _3B −R _4B = (a ₃ ΔR ₃ B ₃ −a ₄ ΔR ₄ B ₄ ) + (b ₃ R ₀₃ −b ₄ R ₀₄ )
(A ₃ ΔR ₃ B ₃ −a ₄ ΔR ₄ B ₄ ) indicates a difference in resistance value due to the input magnetic field. (B ₃ R ₀₃ -b ₄ R ₀₄ ) indicates an offset.

As in the case of the first embodiment, the magnetic sensor 100 of this example can remove the offset by utilizing the characteristic that the initial resistance value of the magnetoresistive element 10 does not substantially vary between the non-bias state and the bias state. The sum of the difference between the resistance values of the first magnetoresistance element 11 and the second magnetoresistance element 12 and the difference between the resistance values of the fourth magnetoresistance element 14 and the third magnetoresistance element 13 is expressed by the following equation.
(Formula 25)
_{[(R 1N -R 2N) -} (R 1B -R 2B)] + [(R 3N -R 4N) - (R 3B -R 4B)]
= [(1-a ₁ ) ΔR ₁ B _1- (1-a ₂ ) ΔR ₂ B ₂ ]
+ [(1-a ₃ ) ΔR ₃ B _3- (1-a ₄ ) ΔR ₄ B ₄ ]

  Thereby, the offset of the first magnetoresistive element 11 to the fourth magnetoresistive element 14 is canceled, and only the resistance component that reacts to the input magnetic field in the X-axis direction remains. Thus, the detection accuracy of the magnetic sensor 100 is improved by removing the offset.

Furthermore, it is preferable that the first magnetoresistive element 11 to the fourth magnetoresistive element 14 have the same magnetic sensitivity ΔR in the X-axis direction, and ΔR ₁ = ΔR ₂ = ΔR ₃ = ΔR ₄ = ΔR. Further, if they are formed on the same chip substrate, the characteristics of the first magnetoresistive element 11 to the fourth magnetoresistive element 14 are substantially equal, so that a ₁ = a ₂ = a ₃ = a ₄ = a. In this case, Equation (25) is expressed by the following equation.
(Formula 26)
_{[(R 1N -R 2N) -} (R 1B -R 2B)] + [(R 3N -R 4N) - (R 3B -R 4B)]
= (1-a) ΔR [(B ₁ −B ₂ ) + (B ₃ −B ₄ )]

The magnetic sensor 100 of this example uses a first magnetoresistive element 11 to a fourth magnetoresistive element 14 as shown in [(B ₁ −B ₂ ) + (B ₃ −B ₄ )]. The difference configuration is taken. Therefore, the magnetic sensor 100 can suppress an error element due to a non-uniform disturbance magnetic field. In this specification, the uniform disturbance magnetic field refers to a magnetic field that uniformly increases in the X-axis direction or a magnetic field that uniformly decreases in the X-axis direction.

[Example 4]
FIG. 8 illustrates an example of a plan view of the magnetic sensor 100 according to the fourth embodiment. FIG. 9 illustrates an example of a cross-sectional view of the magnetic sensor 100 according to the fourth embodiment. A first current conductor 31 and a second current conductor 32 are disposed at both ends of the magnetic sensor 100 of this example. In FIG. 8 and FIG. 9, the magnetic field generator 20 is omitted for simplification.

  The first current conductor 31 and the second current conductor 32 are formed by extending in the Y-axis direction. The first current conductor 31 and the second current conductor 32 are formed on the negative side and the positive side of the X axis of the magnetic sensor 100, respectively. A current flows through the first current conductor 31 and the second current conductor 32 toward the positive side of the Y axis. As a result, a combined magnetic field generated by two currents is generated around the first current conductor 31 and the second current conductor 32.

  The first current conductor 31 and the second current conductor 32 each have a rectangular cross section with a width of 0.85 mm in the X-axis direction and a thickness of 0.4 mm in the Z-axis direction. The first current conductor 31 and the second current conductor 32 have a predetermined distance d3 in the X-axis direction. The distance d3 is 1.7 mm in an example.

  The magnetic sensor 100 is disposed so as to be within the interval d3 in a plan view as viewed from the Z-axis direction. In the magnetic sensor 100, the first plane 51 on which the first magnetoresistive element 11 to the fourth magnetoresistive element 14 are arranged is separated from the upper ends of the first current conductor 31 and the second current conductor 32 by a predetermined distance. Arranged. The upper ends of the first current conductor 31 and the second current conductor 32 indicate the end portions of the first current conductor 31 and the second current conductor 32 on the positive side in the Z-axis direction. In this example, the 1st plane 51 and the upper end of the 1st current conductor 31 and the 2nd current conductor 32 are arrange | positioned 0.1 mm apart.

  The 1st magnetoresistive element 11-the 4th magnetoresistive element 14 are installed so that the symmetry axis s may pass the center of the X-axis direction of the space | interval d3. The first magnetoresistive element 11, the second magnetoresistive element 12, the third magnetoresistive element 13, and the fourth magnetoresistive element 14 are arranged in this order from the negative side to the positive side in the X-axis direction. For example, the first to fourth magnetoresistive elements 11 to 14 have a point passing through the symmetry axis s as the origin (x = 0 mm), and the first magnetoresistive element 11 is −0.7 mm in the X-axis direction. The second magnetoresistive element 12 is arranged at -0.1 mm, the fourth magnetoresistive element 14 is arranged at 0.1 mm, and the third magnetoresistive element 13 is arranged at 0.7 mm.

  FIG. 10 illustrates an example of a magnetic simulation result of the magnetic sensor 100 according to the fourth embodiment. The vertical axis on the left side of the graph indicates the measured magnetic field density Bp [mT], and the vertical axis on the right side of the graph indicates the disturbance magnetic flux density Bn [μT]. The horizontal axis indicates the position in the X-axis direction. The origin corresponds to the position of the symmetry axis s.

  The magnetic field distribution curve (A) indicates the measured magnetic field density Bp. The measured magnetic field density Bp is the magnetic field of the X-axis direction component at each position in the X-axis direction when a current is applied to the first current conductor 31 and the second current conductor 32 toward the positive side of the Y-axis. It is a size. A current of 30 A flows through the first current conductor 31 and the second current conductor 32 of this example.

The measured magnetic field densities Bp for the first magnetoresistive element 11, the second magnetoresistive element 12, the fourth magnetoresistive element 14, and the third magnetoresistive element 13 are 5.8 mT, 2.2 mT, 2.2 mT, and 5. 8 mT. Therefore, (B ₁ −B ₂ ) = (B ₃ −B ₄ ) = 3.6 mT. Therefore, in the formula (26), [(B ₁ −B ₂ ) + (B ₃ −B ₄ )] is 7.2 mT. The measured magnetic field density Bp input to the first magnetoresistive element 11 to the fourth magnetoresistive element 14 is proportional to the magnitude of the current in the Y-axis direction that flows through the first current conductor 31 and the second current conductor 32.

The magnetic field distribution curve (B) shows the disturbance magnetic flux density Bn. The disturbance magnetic flux density Bn is the X-axis direction component magnetic field at each position in the X-axis direction on the first plane 51 when a disturbance current of 60 A flows at a distance of 20 mm from the origin in the X-axis direction. It is a size. The disturbance magnetic flux density Bn input to the first magnetoresistive element 11, the second magnetoresistive element 12, the fourth magnetoresistive element 14, and the third magnetoresistive element 13 is 31.6 μT, 33.8 μT, 34.5 μT, respectively. It becomes 37.0 μT. Therefore, (B ₁ −B ₂ ) = − 2.2 μT, and (B ₃ −B ₄ ) = 2.5 μT. Therefore, in the formula (26), [(B ₁ −B ₂ ) + (B ₃ −B ₄ )] is 0.3 μT. Thus, the magnitude of [(B ₁ −B ₂ ) + (B ₃ −B ₄ )] related to the disturbance magnetic flux density Bn is a disturbance magnetic flux density of about 30 μT input to the magnetoresistive element when the differential configuration is not taken. It is about 1/100 with respect to the size of. That is, the influence of the disturbance magnetic flux density Bn is suppressed.

The magnetic field distribution curve (C) shows a uniform disturbance magnetic field. The uniform disturbance magnetic field is a uniform disturbance magnetic field in the X-axis direction that comes from a distance such as geomagnetism. That is, regarding the uniform disturbance magnetic field, the first magnetoresistive element 11 to the fourth magnetoresistive element 14 detect a uniform magnetic field in the X-axis direction. _Therefore, the _{B 1 = B 2 = B 3} = B 4. That is, in the formula (26), [(B ₁ −B ₂ ) + (B ₃ −B ₄ )] is 0.

  The magnetic sensor 100 of this example is a magnetic sensor that detects a magnetic field generated non-uniformly in the X-axis direction, and can suppress the offset component of the error element and detect the magnetic field generated non-uniformly with high accuracy. Further, since the magnetic sensor 100 of this example has a differential configuration, if the magnitudes of the magnetic fields input to the first magnetoresistive element 11 to the fourth magnetoresistive element 14 are equal, a uniform disturbance magnetic field in the X-axis direction is generated. Can be suppressed. Furthermore, since the magnetic sensor 100 has a double difference configuration, when detecting a non-uniform disturbance magnetic field, an error element due to the non-uniform disturbance magnetic field can be suppressed.

[Example 5]
FIG. 11 illustrates an example of a configuration of the magnetic sensor 100 according to the fifth embodiment. The magnetic sensor 100 of this example includes a first magnetoresistive element 11, a second magnetoresistive element 12, and a third magnetoresistive element 13 as the magnetoresistive element 10.

  The resistance of the third magnetoresistive element 13 changes according to the input magnetic field. The third magnetoresistive element 13 is formed by extending in the Y-axis direction. The third magnetoresistive element 13 of this example has a shape symmetrical to the central axis c3 in plan view. The third magnetoresistive element 13 is formed on the XY plane. The third magnetoresistive element 13 has a magnetosensitive axis in the X-axis direction. That is, the third magnetoresistive element 13 has a magnetosensitive axis parallel to the magnetosensitive axis of the first magnetoresistive element 11.

  The distance d1 between the central axis c1 of the first magnetoresistive element 11 and the central axis c2 of the second magnetoresistive element 12 is between the central axis c2 of the second magnetoresistive element 12 and the central axis c3 of the third magnetoresistive element 13. It is equal to the interval d2. That is, the symmetry axis s is equal to the central axis c2. In other words, the first magnetoresistive element 11 and the third magnetoresistive element 13 are arranged on the first plane 51 so as to be symmetric with respect to the symmetry axis s (that is, d1 = d2).

The magnetic field generator 20 is disposed so as to overlap and cross the first magnetoresistive element 11 to the third magnetoresistive element 13. Thus, the magnetic field generator 20 provides a bias magnetic field _{B V} in the Y-axis direction with respect to the first magneto-resistive element 11 to the third magnetoresistance element 13. For example, the magnetic field generator 20 is formed on the second plane 52 so that the metal wiring extending in the X-axis direction overlaps and crosses the first magnetoresistive element 11 to the third magnetoresistive element 13.

Next, a case where the first current conductor 31 and the second current conductor 32 according to the fourth embodiment are provided in the magnetic sensor 100 of this example will be considered. When a current flows in the positive direction of the Y-axis in the first current conductor 31 and the second current conductor 32, the magnetic field B ₁ in the X-axis direction is applied to each of the first magnetoresistive element 11 to the third magnetoresistive element 13. B ₂ and B ₃ are input. The magnetic fields B ₁ , B ₂ , B ₃ in the X-axis direction are not uniform, for example, B ₁ > B ₂ , B ₃ > B ₂ . The respective resistance values R ₁ , R ₂ , R ₃ of the first magnetoresistive element 11 to the third magnetoresistive element 13 are represented by the following equations.
(Formula 27)
R ₁ = R ₀₁ + ΔR ₁ · B ₁
(Formula 28)
R ₂ = R ₀₂ + ΔR ₂ · B ₂
(Formula 29)
R ₃ = R ₀₃ + ΔR ₃ · B ₃

R ₀₁ , R ₀₂ , and R ₀₃ indicate initial resistance values of the first magnetoresistive element 11 to the third magnetoresistive element 13. ΔR ₁ , ΔR ₂ , ΔR ₃ indicate the magnetic sensitivities of the first magnetoresistive element 11 to the third magnetoresistive element 13. B ₁ , B ₂ , and B ₃ are magnetic fields in the X-axis direction that are input to the first magnetoresistance element 11 to the third magnetoresistance element 13.

(Formula 30)
R ₁ −R ₂ = (ΔR ₁ B ₁ −ΔR ₂ B ₂ ) + (R ₀₁ −R ₀₂ )
(Formula 31)
R ₃ −R ₂ = (ΔR ₃ B ₃ −ΔR ₂ B ₂ ) + (R ₀₃ −R ₀₂ )

(ΔR ₁ B ₁ −ΔR ₂ B ₂ ) is a difference in resistance value due to the input magnetic field of the first magnetoresistive element 11 and the second magnetoresistive element 12. (R ₀₁ -R ₀₂ ) is an offset between the first magnetoresistive element 11 and the second magnetoresistive element 12. Further, (ΔR ₃ B ₃ −ΔR ₂ B ₂ ) is a difference in resistance value due to the input magnetic field of the third magnetoresistive element 13 and the second magnetoresistive element 12. (R ₀₃ -R ₀₂ ) is an offset between the third magnetoresistive element 13 and the second magnetoresistive element 12.

The magnetic sensor 100 of this example has a calculation unit described later, and the difference between the resistance values of the first magnetoresistive element 11 and the second magnetoresistive element 12 and the third magnetoresistive element 13 and the second magnetoresistive element 12. The sum of the difference between the resistance values is detected.
(Formula 32)
(R ₁ −R ₂ ) + (R ₃ −R ₂ )
= [(ΔR ₁ B ₁ −ΔR ₂ B ₂ ) + (ΔR ₃ B ₃ −ΔR ₂ B ₂ )]
+ [(R ₀₁ -R ₀₂ ) + (R ₀₃ -R ₀₂ )]

[(R ₀₁ −R ₀₂ ) + (R ₀₃ −R ₀₂ )] is the offset of the first magnetoresistive element 11 and the second magnetoresistive element 12, and the third magnetoresistive element 13 and the second magnetoresistive element 12. This is the offset of the sum of the offset.

  Next, a difference in resistance value between the first magnetoresistance element 11 and the second magnetoresistance element 12 and a difference in resistance difference between the third magnetoresistance element 13 and the second magnetoresistance element 12 will be considered.

The difference between the resistance values of the first magnetoresistive element 11 and the second magnetoresistive element 12 is expressed by the following equation in the non-bias state.
(Formula 33)
R _1N −R _2N = (ΔR ₁ B ₁ −ΔR ₂ B ₂ ) + (R ₀₁ −R ₀₂ )
(ΔR ₁ B ₁ −ΔR ₂ B ₂ ) indicates a difference in resistance value due to the input magnetic field. (R ₀₁ -R ₀₂ ) indicates an offset.

The difference between the resistance values of the first magnetoresistive element 11 and the second magnetoresistive element 12 is expressed by the following equation in the bias state. In bias state, the magnetic sensitivity of the first magnetoresistance element 11 and the second magnetoresistance element 12, the magnetic sensitivity [Delta] R ₁ under no bias state, ₁ × _a respectively [Delta] R _2, changes _{twice a.} The initial resistance value in the bias state changes to b ₁ times and b ₂ times the initial resistance values R ₀₁ and R ₀₂ of the first magnetoresistive element 11 and the second magnetoresistive element 12 in the non-bias state, respectively. .
(Formula 34)
R _1B −R _2B = (a ₁ ΔR ₁ B ₁ −a ₂ ΔR ₂ B ₂ ) + (b ₁ R ₀₁ −b ₂ R ₀₂ )
(A ₁ ΔR ₁ B ₁ −a ₂ ΔR ₂ B ₂ ) indicates a difference in resistance value due to an input magnetic field. (B ₁ R ₀₁ -b ₂ R ₀₂ ) indicates an offset.

Further, the difference between the resistance values of the third magnetoresistive element 13 and the second magnetoresistive element 12 is expressed by the following equation in the non-bias state.
(Formula 35)
R _3N −R _2N = (ΔR ₃ B ₃ −ΔR ₂ B ₂ ) + (R ₀₃ −R ₀₂ )
(ΔR ₃ B ₃ −ΔR ₂ B ₂ ) indicates a difference in resistance value due to the input magnetic field. (R ₀₃ -R ₀₂ ) indicates an offset.

The difference between the resistance values of the third magnetoresistive element 13 and the second magnetoresistive element 12 is expressed by the following equation in the bias state. In bias state, the magnetic sensitivity of the third magnetoresistance element 13 and the second magnetoresistance element 12, the magnetic sensitivity [Delta] R ₃ under no bias state, _three times _a respectively [Delta] R _2, changes _{twice a.} The initial resistance value in the bias state changes to b ₃ times and b ₂ times the initial resistance values R ₀₃ and R ₀₂ of the third magnetoresistive element 13 and the second magnetoresistive element 12 in the non-bias state, respectively. .
(Formula 36)
R _3B −R _2B = (a ₃ ΔR ₃ B ₃ −a ₂ ΔR ₂ B ₂ ) + (b ₃ R ₀₃ −b ₂ R ₀₂ )
(A ₃ ΔR ₃ B ₃ −a ₂ ΔR ₂ B ₂ ) indicates a difference in resistance value due to the input magnetic field. (B ₃ R ₀₃ -b ₂ R ₀₂ ) indicates an offset.

As in the first embodiment, the magnetic sensor 100 of this example can remove the offset by utilizing the characteristic that the initial resistance value of the magnetoresistive element does not substantially vary between the non-bias state and the bias state. The sum of the difference between the resistance values of the first magnetoresistance element 11 and the second magnetoresistance element 12 and the difference between the resistance values of the third magnetoresistance element 13 and the second magnetoresistance element 12 is expressed by the following equation.
(Formula 37)
_{[(R 1N -R 2N) -} (R 1B -R 2B)] + [(R 3N -R 2N) - (R 3B -R 2B)]
= [(1-a ₁ ) ΔR ₁ B _1- (1-a ₂ ) ΔR ₂ B ₂ ]
+ [(1-a ₃ ) ΔR ₃ B _3- (1-a ₂ ) ΔR ₂ B ₂ ]
Therefore, the magnetic sensor 100 can cancel the offset of the three magnetoresistive elements, and only the resistance component that reacts to the input magnetic field in the X-axis direction remains. Thus, the detection accuracy of the magnetic sensor 100 is improved by removing the offset.

Furthermore, the first magnetoresistive element 11 to the third magnetoresistive element 13 preferably have the same magnetic sensitivity ΔR in the X-axis direction, and ΔR ₁ = ΔR ₂ = ΔR ₃ = ΔR. Further, if they are formed on the same chip substrate, the characteristics of the first magnetoresistive element 11 to the third magnetoresistive element 13 are substantially uniform, so a ₁ = a ₂ = a ₃ = a, Expression 37) is expressed by the following expression.
(Formula 38)
_{[(R 1N -R 2N) -} (R 1B -R 2B)] + [(R 3N -R 2N) - (R 3B -R 2B)]
= (1-a) ΔR [(B ₁ −B ₂ ) + (B ₃ −B ₂ )]

  The magnetic sensor 100 of this example is a magnetic sensor that detects a magnetic field generated non-uniformly in the X-axis direction, and can suppress the offset component of the error element and detect the magnetic field generated non-uniformly with high accuracy. In addition, since the magnetic sensor 100 of this example has a differential configuration, if the magnitudes of the magnetic fields input to the first magnetoresistive element 11 to the third magnetoresistive element 13 are equal, a uniform disturbance magnetic field in the X-axis direction is generated. Can be suppressed. Furthermore, since the magnetic sensor 100 has a double difference configuration, when detecting a non-uniform disturbance magnetic field, an error element due to the non-uniform disturbance magnetic field can be suppressed.

  The magnetic sensor 100 of this example includes three magnetoresistive elements. Therefore, the magnetic sensor 100 of this example can reduce the mismatch between the magnetoresistive elements as compared with the case of using four magnetoresistive elements.

  FIG. 12 shows an exemplary configuration of the control system 300. The control system 300 of this example includes a magnetic sensor 100 and a control device 200. The control device 200 includes a calculation unit 210, a current generation circuit 220, a current source 241 and a current source 242.

  One end of the current source 241 is connected to the first magnetoresistive element 11, and the other end is electrically coupled to one point to receive the first potential 231. The other end of the first magnetoresistive element 11 is electrically coupled to one point and given a second potential 232.

  One end of the current source 242 is connected to the second magnetoresistive element 12, and the other end is electrically coupled to one point, and a first potential 231 is applied. The other end of the second magnetoresistive element 12 is electrically coupled to one point and given a second potential 232. In one example, the first potential 231 is the power supply potential VDD of the power supply device, and the second potential 232 is the ground potential GND. However, the first potential 231 and the second potential 232 are not limited to this.

  The calculation unit 210 calculates a magnetic signal based on the output signal of the magnetic sensor 100. In one example, the calculation unit 210 calculates the difference between the measured value of the magnetic sensor 100 in the non-biased state and the measured value of the magnetic sensor 100 in the biased state. In addition, the calculation unit 210 calculates a difference between the output signal of the first magnetoresistance element 11 and the output signal of the second magnetoresistance element 12. For example, the calculation unit 210 performs the calculation shown in the example of the present specification as the calculation based on the output signals of the first magnetoresistive element 11 and the second magnetoresistive element 12.

  The current generation circuit 220 generates a current for driving the magnetic field generator 20 at an arbitrary timing. In one example, the current generation circuit 220 outputs information indicating whether or not a current is supplied to the magnetic field generation device 20 to the calculation unit 210. Thereby, the arithmetic part 210 can determine whether the output signal of the magnetic sensor 100 is an output signal in a no-bias state or an output signal in a bias state.

  As mentioned above, although this invention was demonstrated using embodiment, the technical scope of this invention is not limited to the range as described in the said embodiment. It will be apparent to those skilled in the art that various modifications or improvements can be added to the above-described embodiment. It is apparent from the scope of the claims that the embodiments added with such changes or improvements can be included in the technical scope of the present invention.

  The execution order of each process such as operation, procedure, step, and stage in the apparatus, system, program, and method shown in the claims, the description, and the drawings is particularly “before” or “prior to”. It should be noted that the output can be realized in any order unless the output of the previous process is used in the subsequent process. Regarding the operation flow in the claims, the specification, and the drawings, even if it is described using “first”, “next”, etc. for the sake of convenience, it means that it is essential to carry out in this order. It is not a thing.

DESCRIPTION OF SYMBOLS 10 ... Magnetoresistive element, 11 ... 1st magnetoresistive element, 12 ... 2nd magnetoresistive element, 13 ... 3rd magnetoresistive element, 14 ... 4th magnetoresistive element, .. Magnetic field generator, 31 ... first current conductor, 32 ... second current conductor, 40 ... substrate, 42 ... insulating layer, 50 ... substrate plane, 51 ... first Planar, 52... Second plane, 100... Magnetic sensor, 200... Control device, 210... Calculation unit, 220 ... Current generation circuit, 231 ... First potential, 232. Second potential, 241 ... current source, 242 ... current source, 300 ... control system

Claims (21)

A first magnetoresistive element;
By generating a bias magnetic field and applying the bias magnetic field to the first magnetoresistive element, the state of the first magnetoresistive element is changed from a first state having a predetermined magnetic sensitivity to the first state. A magnetic sensor comprising: a magnetic field generator that changes to a second state having different magnetic sensitivities. The magnetic sensor according to claim 1, wherein magnetic sensitivity of the first magnetoresistive element in the first state is greater than magnetic sensitivity of the first magnetoresistive element in the second state. The magnetic sensor according to claim 2, wherein an initial resistance value of the first magnetoresistance element in the first state is equal to an initial resistance value of the first magnetoresistance element in the second state. The magnetic sensor according to any one of claims 1 to 3, wherein the magnetic field generation device generates the bias magnetic field including at least a component in a direction different from a magnetosensitive axis of the first magnetoresistive element. The magnetic sensor according to any one of claims 1 to 3, wherein the magnetic field generation device generates the bias magnetic field including at least a component perpendicular to a magnetosensitive axis of the first magnetoresistive element. The magnetic sensor according to any one of claims 1 to 3, wherein the magnetic field generation device generates the bias magnetic field perpendicular to a magnetosensitive axis of the first magnetoresistive element. The magnetic sensor according to claim 1, wherein the magnetic field generation device does not generate the bias magnetic field in the first state and generates the bias magnetic field in the second state. The magnetic sensor according to claim 1, further comprising an arithmetic unit that calculates a difference between output signals of the first magnetoresistive element in the first state and the second state. A second magnetoresistive element having a magnetosensitive axis parallel to the magnetosensitive axis of the first magnetoresistive element;
The magnetic sensor according to claim 1, wherein the magnetic field generator applies the bias magnetic field to each of the first magnetoresistive element and the second magnetoresistive element. The magnetic sensor according to claim 9, wherein the magnetic field generator applies the bias magnetic field having the same intensity to the first magnetoresistive element and the second magnetoresistive element. The magnetic sensor according to any one of claims 1 to 10, wherein the magnetic field generator is formed to extend in parallel with a magnetosensitive axis of the first magnetoresistive element. A difference between output signals of the first magnetoresistive element and the second magnetoresistive element in the first state; a difference between output signals of the first magnetoresistive element and the second magnetoresistive element in the second state; The magnetic sensor according to claim 9, further comprising a calculation unit that calculates a difference between the two. The difference between the initial resistance value of the first magnetoresistive element in the first state and the initial resistance value of the first magnetoresistive element in the second state is the initial value of the second magnetoresistive element in the first state. The magnetic sensor according to claim 9 or 10, wherein a difference between a resistance value and an initial resistance value of the second magnetoresistance element in the second state is equal. The difference between the initial resistance value of the first magnetoresistive element in the first state and the initial resistance value of the second magnetoresistive element in the first state is the initial value of the first magnetoresistive element in the second state. The magnetic sensor according to claim 9 or 10, wherein a difference between a resistance value and an initial resistance value of the second magnetoresistance element in the second state is equal. A second magnetoresistive element having a magnetosensitive axis parallel to the magnetosensitive axis of the first magnetoresistive element;
A third magnetoresistive element having a magnetosensitive axis parallel to the magnetosensitive axis of the first magnetoresistive element;
The distance between the central axis of the first magnetoresistive element and the central axis of the second magnetoresistive element is equal to the distance between the central axis of the second magnetoresistive element and the central axis of the third magnetoresistive element. The magnetic sensor according to any one of 1 to 7. An arithmetic unit is further provided for calculating a difference between a difference between output signals of the first magnetoresistive element and the second magnetoresistive element and a difference between output signals of the second magnetoresistive element and the third magnetoresistive element. The magnetic sensor according to claim 15. A second magnetoresistive element having a magnetosensitive axis parallel to the magnetosensitive axis of the first magnetoresistive element;
A third magnetoresistive element having a magnetosensitive axis parallel to the magnetosensitive axis of the first magnetoresistive element;
A fourth magnetoresistive element having a magnetosensitive axis parallel to the magnetosensitive axis of the first magnetoresistive element,
The distance between the central axis of the first magnetoresistive element and the central axis of the second magnetoresistive element is equal to the distance between the central axis of the third magnetoresistive element and the central axis of the fourth magnetoresistive element. The magnetic sensor according to any one of 1 to 7. The first magnetoresistive element and the third magnetoresistive element are arranged symmetrically across a predetermined axis of symmetry,
The magnetic sensor according to claim 17, wherein the second magnetoresistive element and the fourth magnetoresistive element are arranged symmetrically with respect to the symmetry axis. The first magnetoresistive element is formed between the third magnetoresistive element and the fourth magnetoresistive element,
The magnetic sensor according to claim 18, wherein the third magnetoresistive element is formed between the first magnetoresistive element and the second magnetoresistive element. The magnetic sensor according to claim 18, wherein the first magnetoresistive element and the second magnetoresistive element are formed on opposite sides of the third magnetoresistive element and the fourth magnetoresistive element with the axis of symmetry interposed therebetween. An arithmetic unit is further provided for calculating a difference between a difference between output signals of the first magnetoresistive element and the second magnetoresistive element and a difference between output signals of the third magnetoresistive element and the fourth magnetoresistive element. The magnetic sensor as described in any one of Claims 17-20.

Images