JP6723630B2 - Magnetic detection device - Google Patents

Description

INDUSTRIAL APPLICABILITY The present invention makes it possible to easily detect the magnetic field strength and the magnetic field that can be detected in a wide dynamic range (measurable range) by using a multilayer film GMR element for a magnetic field generated from a magnetic field generation source such as a measured current. The present invention relates to a magnetic detection device capable of detecting.

As a conventional non-contact type current sensor, a magnetic detection device using a magnetoresistive effect element has been proposed. The magnetic sensor device described in Patent Document 1 is a GMR element in which a magnetic layer and a non-magnetic layer are alternately laminated as a first detection unit that outputs a first electric signal indicating the strength of a magnetic field. Is used. This GMR element can detect the strength of the magnetic field, but cannot detect the direction of the magnetic field. Therefore, a second detection unit that outputs a second electric signal that indicates the direction of the magnetic field and a processing circuit that specifies the direction of the magnetic field using the polarity of the second electric signal of the second detection unit as an index are provided. ing.

The second detection means is a piezoelectric element having a thin portion. When a magnetic field acts in a state in which an electric current is applied to the thin portion, the Lorentz force causes the thin portion to follow the direction of the magnetic field and bend. Voltages having different polarities depending on the bending direction at this time are output as the second electric signal.

JP, 2007-218760, A

The magnetic sensor device described in Patent Document 1 uses a piezoelectric element having a thin portion as the second detecting means for detecting the direction of the magnetic field. However, this piezoelectric element is mechanical in the thin portion. Since the Lorentz force, which is a force, is applied to bend the thin portion, the response is poor and it is difficult to follow the direction of the magnetic field that changes at high frequencies.

Further, in this magnetic sensor device, a first electric signal indicating the strength of the magnetic field detected by the GMR element and a second electric signal indicating the direction of the magnetic field detected by the piezoelectric element are taken out as separate outputs. However, it is not possible to obtain a single output whose polarity changes when the direction of the magnetic field changes.

The present invention solves the problems of the related art, and can respond to a relatively strong magnetic field by using a multi-layer GMR element, can detect a magnetic field in a wide dynamic range, and can quickly change the direction of the magnetic field. It is an object of the present invention to provide a magnetic detection device that can obtain a responding detection output.

The magnetic detection device of the present invention includes a magnetic field strength detection unit, a magnetic field direction detection unit, and a switch unit,
The magnetic field strength detection unit,
A first resistance element, which is a multi-layer GMR element in which ferromagnetic layers and non-magnetic material layers are alternately laminated, and a multi-layer in which detection sensitivity to a magnetic field from the same magnetic field generation source is different from that of the first resistance element. A first series circuit in which a film GMR element or a second resistance element which is a fixed resistance is connected in series;
A second series circuit in which the second resistance element and the first resistance element are connected in series,
The same voltage is applied to the first series circuit and the second series circuit,
A first differential output voltage between the midpoint outputs of the first resistance element and the second resistance element in the first series circuit and the second series circuit; and the first differential output voltage. And a second differential output voltage obtained by inverting the polarity of the output voltage is output to the switch unit,
In the magnetic field direction detection unit,
A detection output whose polarity changes according to the direction of the magnetic field is output to the switch unit,
The switch unit selects either the first differential output voltage or the second differential output voltage as a detection output voltage according to the polarity of the detection output from the magnetic field direction detection unit. It is characterized by.

In the present invention, the second resistance element may be a multi-layer GMR element having the same film structure and the same size as the first resistance element.
The first resistance element and the second resistance element may have different distances to the same magnetic field generation source.
Alternatively, the first resistance element and the second resistance element may be different in installation of a magnetic shield between the same magnetic field generation source.

The first resistance element and the second resistance element may have different installation directions with respect to the magnetic field of the same magnetic field generation source.
The first resistance element is provided such that the film surface direction of the multi-layer film GMR element is parallel to the magnetic field of the magnetic field generation source, and the second resistance element is the film thickness direction of the multi-layer film GMR element. May be provided in parallel with the magnetic field of the magnetic field generation source.

In each of the multilayer GMR elements, the antiferromagnetic layer may be provided in contact with one or both of the ferromagnetic layers located at the outermost layer.

Further, in the present invention, it is preferable that the magnetic field direction detection unit includes a bridge circuit having a spin valve type GMR element.
Further, the magnetic field direction detection unit may include a bridge circuit having a Hall element.

In the magnetic detection device of the present invention, the resistance element includes a multilayer GMR element in which a ferromagnetic layer, a plurality of ferromagnetic layers, and a plurality of nonmagnetic layers are alternately laminated. Since the multi-layer GMR element obtains an even function output, even if the bridge circuit is simply connected in series and the midpoint potential is used as the detection output voltage, the midpoint potential is not affected by the change in the magnetic field. It never changes.

Therefore, in the present invention, differential output voltages having different polarities are taken out from the bridge circuit, and the switch section selects one of the two differential output voltages based on the polarity of the detection output of the magnetic field direction detection section. .. Therefore, even when the direction of the magnetic field to be measured changes, a single output indicating the direction and magnitude can be obtained.

Further, since the multi-layer GMR element has a large saturation magnetic field strength, it is possible to configure a magnetic detection device having a wide measurable range (dynamic range) for a relatively strong magnetic field.

Furthermore, by configuring the magnetic field direction detection unit with a spin valve type GMR element or the like, the polarity of the detection output of the magnetic field direction detection unit can be inverted by reacting sensitively to changes in the direction of the magnetic field to be measured. .. Therefore, even if the direction of the magnetic field to be measured changes at a high frequency, it is possible to obtain a magnetic detection output that follows and changes.

Circuit block diagram of a current sensor 1 using a magnetic detection device according to a first embodiment of the present invention, Explanatory drawing which shows the film|membrane structure of the multilayer film GMR element which is the 1st resistance element 11 used for the magnetic detection apparatus of the 1st Embodiment of this invention, 2A and 2B are explanatory views showing a state in which a magnetic field is not applied to the multilayer film GMR element which is the first resistance element 11 shown in FIG. 2 and a state in which a magnetic field less than the saturation magnetic field strength is applied. FIG. 6C is an explanatory view showing a state in which a magnetic field having a saturation magnetic field strength or higher is applied, A graph showing the resistance change of the multilayer GMR element with respect to the change in the direction and strength of the magnetic field, A graph showing a change in the midpoint voltage of the first series circuit A and a change in the midpoint voltage of the second series circuit B of the magnetic field strength detection unit with respect to changes in the direction and strength of the magnetic field, A graph showing changes in the second differential output voltage (VoutB-VoutA) with respect to changes in the direction and strength of the magnetic field, A graph showing changes in output corresponding to the direction and strength of the magnetic field of the spin-valve GMR element provided in the magnetic field direction detection unit shown in FIG. A graph showing the output voltage of the magnetic detection device used in the current sensor 1, Circuit block diagram of a current sensor 2 using a magnetic detection device according to a second embodiment of the present invention, A graph showing R-H waveforms of the first resistance element 41 and the second resistance element 42 which constitute the magnetic detection device used in the current sensor 2, A graph showing the output voltage of the magnetic detection device used in the current sensor 2, Circuit block diagram of a current sensor 3 using a magnetic detection device according to a third embodiment of the present invention, A graph showing R-H waveforms of the first resistance element 51 and the second resistance element 52 that constitute the magnetic detection device used in the current sensor 3, A graph showing the output voltage of the magnetic detection device used for the current sensor 3, Circuit block diagram of a current sensor 4 using a magnetic detection device according to a fourth embodiment of the present invention, Explanatory drawing which shows the modification of the film structure of the multilayer film GMR element used for the magnetic detection apparatus which concerns on the 1st-4th embodiment of this invention,

<First Embodiment>
FIG. 1 is a circuit block diagram of a current sensor 1 using a magnetic detection device according to an embodiment of the present invention. As shown in the figure, the magnetic detection device used in the current sensor 1 includes a magnetic field strength detection unit 10, a magnetic field direction detection unit 20, and a switch unit 30.

The magnetic field strength detection unit 10 includes first resistance elements 11A and 11B and second resistance elements 12A and 12B. When the first resistance elements 11A and 11B are not distinguished, they are referred to as the first resistance element 11, and when the second resistance elements 12A and 12B are not distinguished, they are referred to as the second resistance element 12. In the following, when the members identified by adding A and B to the numbers are not distinguished, A and B are omitted as appropriate and only the numbers are described.

The first resistance element 11 is a multi-layer GMR element, and the second resistance element 12 is a fixed resistance element. The multilayer GMR element has a characteristic that the saturation magnetic field strength is large and the characteristics are not deteriorated even when receiving a large magnetic field. Therefore, the current sensor 1 can detect a large current.

In the magnetic field strength detection unit 10, a first resistance element 11A which is a multi-layered film GMR element and a second resistance element 12A which is a fixed resistance element are connected in series to form a first series circuit A, which is fixed. The second resistance element 12B, which is a resistance element, and the first resistance element 11B, which is a multilayer film GMR element, are connected in series to form a second series circuit B. The first end 13 of the first series circuit A and the second series circuit B connected in parallel is connected to the first potential source (Vdd), and the second end 14 is connected to the second potential source (GND). It is connected. The sensor output end 15A, which is the midpoint of the first series circuit A, and the sensor output end 15B, which is the midpoint of the second series circuit B, are connected to the differential amplifiers 16A and 16B. The differential amplifier 16A outputs the first differential output voltage (VoutA-VoutB) of the sensor output end 15A-the sensor output end 15B to the switch unit 30, and the differential amplifier 16B outputs the sensor output end 15B-the sensor output end 15A. The second differential output voltage (VoutB−VoutA) is output to the switch unit 30.

FIG. 2 shows an example of the film configuration of the multi-layered film GMR element that constitutes the first resistance element 11.
The multilayer GMR element has a multilayer structure layer 114 in which a ferromagnetic layer 112 and a nonmagnetic material layer 113 are alternately stacked between a base layer 111 and a protective layer 115. In the multilayer structure layer 114, the ferromagnetic layer 112 is antiferromagnetically coupled by the RKKY interlayer interaction via the nonmagnetic material layer 113. Therefore, the ferromagnetic layers 112 adjacent to the non-magnetic material layer 113 have opposite magnetization directions as indicated by arrows in the figure. These layers are formed by, for example, a sputtering process.

When an external magnetic field in a direction along the magnetization direction of the ferromagnetic layer 112 is applied to the multilayer structure layer 114, the magnetizations of all the ferromagnetic layers 112 tend to be aligned in the direction of the external magnetic field. At this time, the resistance value of the multilayer GMR element is increased by the giant magnetoresistive effect (GMR effect) according to the opposite directions of the magnetization vectors of the pair of ferromagnetic layers 112 that face each other with the nonmagnetic material layer 113 interposed therebetween. Change.

In the multilayer structure layer 114, the magnetization of the ferromagnetic layer 112 is oriented antiparallel. Therefore, the resistance value changes symmetrically when the direction of the external magnetic field H changes in one direction (positive direction) and in the other direction (negative direction) along the magnetization direction of the ferromagnetic layer 112. .. That is, the change in the resistance value with respect to the change in the strength of the external magnetic field appears as an even function. The number of layers of the multilayer structure layer 114 and the thickness of each layer are set according to the required saturation magnetic field strength (magnetic field strength at which the magnetization state does not change).

The base layer 111 of the multilayer film GMR element is formed of NiFeCr alloy (nickel, iron, chromium alloy), Cr, or the like. The ferromagnetic layer 112 is formed of an alloy whose main component is one or more selected from the group consisting of Fe, Co, Ni and alloys thereof. When the ferromagnetic layer 112 is formed of a FeCo alloy (iron, cobalt alloy), the coercive force is increased by increasing the content ratio of Fe.

The nonmagnetic material layer 113 is Cu (copper), Cr (chrome), Ru (ruthenium), or the like. In order to cause RKKY interlayer interaction between the paired ferromagnetic layers 112, the thickness of the non-magnetic material layer 113 is preferably 7 to 13Å or 16 to 24Å in the case of Cu (copper), and Cr In the case of (chrome), it is preferably 7 to 13Å or 19 to 27Å, and in the case of Ru (ruthenium), it is preferably 3 to 5Å or 8 to 10Å.

FIGS. 3A, 3B, and 3C show the multi-layered structure when the direction and strength of the external magnetic field H applied to the multi-layered film GMR element, which is the first resistance element 11 shown in FIG. The change state of the magnetization direction of the structure layer 114 is shown. When the external magnetic field strength that affects the multilayer structure layer 114 is zero (zero magnetic field), the magnetization vectors of the antiferromagnetically coupled ferromagnetic layers 112 are staggered as shown in FIG. 3A. The absolute value is the same. At this time, the resistance value becomes a maximum value. As shown in FIG. 3B, when the external magnetic field H, which is weaker than the saturation magnetic field, acts in the right direction in the figure, which is the direction of magnetization of the ferromagnetic layer 112, the magnetization of the ferromagnetic layer 112 is in the right direction in the figure. Since it is dominant in the direction, the resistance value is slightly low. As shown in FIG. 3C, when the external magnetic field H, which is larger than the saturation magnetic field, acts in the right direction in the drawing, the magnetization directions of the ferromagnetic layers 112, which are opposite to each other, are aligned in the same right direction as the external magnetic field H. At this time, the resistance value becomes a minimum value.

Even when the external magnetic field H acts in the leftward direction in the drawing, changes in the external magnetic field and the resistance value of each ferromagnetic layer 112 are different from those in the directions in which the magnetization changes, as shown in FIGS. Similar to c).

In the graph shown in FIG. 4, the horizontal axis represents the change in the direction and magnitude of the external magnetic field H along the direction of the magnetization of the ferromagnetic layer 112, and the vertical axis represents the change in the resistance value of the multilayer GMR element. Is shown. Arrows shown at four positions in FIG. 4 indicate changes in magnetization of the plurality of ferromagnetic layers 112 according to changes in the external magnetic field H. The resistance value of the multilayer film GMR element becomes maximum when the magnetic field strength is zero, and the resistance value decreases as the component of the magnetic field strength (external magnetic field H) in any direction increases, and the resistance value goes to any direction. When the magnitude of the magnetic field H becomes equal to or higher than the saturation magnetic field strength, the resistance value does not change and the resistance value becomes minimum. That is, the change in the resistance value with respect to the change in the external magnetic field H in the two opposite directions becomes an even function.

The multilayer GMR element is characterized in that the resistance changes depending on the magnitude of the magnetic field strength, the resistance change rate (R/R ₀ ) in the measurable range is high, and the saturation magnetic field strength is large. The saturation magnetic field strength of the multilayer GMR element is, for example, 100 mT or more.

FIG. 5 shows changes in the potential (VoutA) of the sensor output end 15A in the series circuit A shown in FIG. 1 and changes in the potential (VoutB) of the sensor output end 15B in the series circuit B. The potential change at the sensor output end 15A and the potential change at the sensor output end 15B have opposite polarities. The second differential output voltage (VoutB-VoutA) output from the operational amplifier 16B appears with the waveform shown in FIG. 6 with respect to the change of the external magnetic field, and the first differential output output from the differential amplifier 16A. The voltage (VoutA-VoutB) appears in a vertically symmetrical waveform with respect to FIG. 6 with respect to changes in the external magnetic field. The voltage value on the vertical axis in FIG. 6 is shown in a range smaller than the voltage value on the vertical axis shown in FIG. In FIG. 8, a change in the first differential output voltage (VoutA-VoutB) is shown by a solid line, and a change in the second differential output voltage (VoutB-VoutA) is shown by a one-dot chain line.

Since the multilayer film GMR element used as the first resistance elements 11A and 11B of the magnetic field strength detection unit 10 has a large saturation magnetization, it can exhibit a resistance change within the range of a strong magnetic field. Therefore, as shown in FIG. 8, for example, in a strong magnetic field of about ±500 mT, the first differential output voltage (VoutA-VoutB) and the second differential output voltage (VoutB-VoutA) show output changes. It is possible to secure a wide dynamic range.

However, as shown by the solid line in FIG. 8, the first differential output voltage (VoutA−VoutB) changes with an even function with respect to the change in the direction of the external magnetic field H, and as shown by the one-dot chain line in FIG. , The second differential output voltage (VoutB−VoutA) changes as an even function with respect to the change in the direction of the external magnetic field H, and the change in the direction of the external magnetic field H cannot be identified. Therefore, in the current sensor 1, the first differential output voltage and the second differential output voltage are output to the switch unit 30, and the switch unit is detected based on the identification of the magnetic field direction detected by the magnetic field direction detection unit 20. 30 switches and outputs either the first differential output voltage (VoutA-VoutB) or the second differential output voltage (VoutB-VoutA).

The magnetic field direction detection unit 20 outputs to the switch unit 30 a detection voltage whose polarity changes depending on the magnetic field direction due to the measured current line 5 in the current sensor 1. The magnetic field direction detection unit 20 shown in FIG. 1 has a full bridge configuration including third resistance elements 21A and 21B and fourth resistance elements 22A and 22B. The magnetic field direction detection unit 20 may be a circuit having a half bridge configuration, as long as it can detect the magnetic field direction.

The third resistance element 21 is a spin valve type GMR element which is an element whose output changes according to the magnetic field direction. In the spin valve type GMR element, a pinned magnetic layer whose magnetization direction is fixed and a free magnetic layer whose magnetization direction changes in accordance with external magnetization are laminated with a nonmagnetic layer interposed therebetween. The fourth resistance element 22 is a spin valve type GMR element or a fixed resistance in which the direction of fixed magnetization of the fixed magnetic layer is opposite to that of the third resistance element 21. In the magnetic field direction detection unit 20 shown in FIG. 1, the midpoint potential between the third resistance element 21A and the fourth resistance element 22A, and the midpoint potential between the fourth resistance element 22B and the third resistance element 21B. Is obtained as the output of the comparator 23. The comparator 23 of the magnetic field direction detection unit 20 compares the differential output voltage with the threshold value, detects the magnetic field direction, and outputs the detected magnetic field direction to the switch unit 30. In order to prevent the detection result in the magnetic field direction near the threshold value from changing frequently due to the influence of noise, it is preferable that the comparator 23 has a hysteresis.

FIG. 7 shows the detection output from the comparator 23 of the magnetic field direction detection unit 20 using the spin valve type GMR element. By changing the direction of the fixed magnetization of the fixed magnetic layer of the spin-valve type GMR element forming the third resistance element 21 in parallel or anti-parallel to the external magnetic field to be measured, the change of the direction of the magnetic field is changed. Depending on the polarity, detection outputs with different polarities can be obtained. The third resistance element 21 is not limited to the spin valve type GMR element as long as it is an element that can obtain an output having different polarities depending on the direction of the magnetic field, and an AMR (Anisotropic-Magneto-Resistive) element, A Hall element or the like can also be used. It is also possible to form a bridge circuit with an AMR element or a Hall element.

The switch unit 30 shown in FIG. 1 has a first differential output voltage (VoutA-VoutB) and a second differential output voltage (VoutB-VoutA) according to a change in the polarity of the detection output from the magnetic field direction detection unit 20. ) And switch. As a result, the detection output voltage (Vout) of the magnetic detection device shown in FIG. 1 is such that the thick chain line shown in FIG. 8 and the thick solid line are continuous. That is, as a single detection output voltage (Vout), an output having different polarities is obtained by a change in the external magnetic field, for example, a change in the direction of the measured magnetic field according to a change in the direction of the measured current line 5 in the current sensor 1. You can

<Second Embodiment>
FIG. 9 is a circuit block diagram of the current sensor 2 using the magnetic detection device according to the embodiment of the present invention. In the embodiments after the present embodiment, the same numbers are given to the members that have already been described, and detailed description will be omitted. As shown in FIG. 9, the magnetic sensor used in the current sensor 2 includes the magnetic field strength detection unit 40 instead of the magnetic field strength detection unit 10, and thus the current sensor described in the first embodiment. It is different from 1.

The first resistance elements 41A and 41B and the second resistance elements 42A and 42B in the magnetic field strength detection unit 40 shown in FIG. 9 are multilayer GMR elements having the same film configuration and the same dimensions. The characteristics are shown.

In the magnetic detection device provided in the current sensor 2, the distance d1 from the first resistance element 41A, 41B to the measured current line 5 which is the magnetic field generation source and the second resistance element 42A, 42B from the magnetic field generation source. And the distance d2 to the measured current line 5 is different. The strength of the magnetic field induced in the first resistance element 41 and the strength of the magnetic field induced in the second resistance element 42 differ due to the current flowing through the measured current line 5, The acting magnetic field is stronger than the magnetic field acting on the second resistance element 42. Therefore, the detection sensitivity of the first resistance element 41 is substantially higher than the detection sensitivity of the second resistance element 42.

The sensitivity of the first resistance element 41 and the sensitivity of the second resistance element 42 to the current flowing through the measured current line 5 are substantially changed by varying the distance to the measured current line 5 that is the magnetic field generation source. Can be different. The difference between the distance d1 and the distance d2 is preferably d1<d2<5d1, and more preferably 1.5d1<d2<2.5d1.

FIG. 10 is a graph showing an RH waveform of the multilayer GMR element that constitutes the current sensor 1. The first resistance element 41 has substantially higher detection sensitivity than the second resistance element 42. Therefore, when the amount of current flowing through the measured current line 5 changes in the plus direction and the minus direction and the external magnetic field H changes in the opposite directions along one direction, the change in the resistance value is caused by the first resistance element. While 41 (displayed by a solid line) is steep, the second resistance element 42 (displayed by a broken line) is steep.

In FIG. 11, the first differential output voltage (VoutA-VoutB) is shown by a solid line, and the second differential output voltage (VoutB-VoutA) is shown by a one-dot chain line. In the switch unit 30 shown in FIG. 9, the first differential output voltage (VoutA-VoutB) and the second differential output voltage (VoutB-VoutA) are changed according to the change in the polarity of the detection output from the magnetic field direction detection unit 20. ) And switch. As a result, the detection output voltage (Vout) of the magnetic detection device is such that the thick chain line shown in FIG. 11 and the thick solid line are continuous. That is, in the measurable range shown in FIG. 11, as a single detection output voltage (Vout), a change in the external magnetic field, for example, a change in the direction of the measured magnetic field according to the change in the direction of the current line 5 to be measured in the current sensor 1. It is possible to obtain outputs with different polarities.

<Third Embodiment>
FIG. 12 is a circuit block diagram of the current sensor 3 according to the third embodiment of the present invention. As shown in the figure, the magnetic sensor used in the current sensor 3 includes a magnetic field strength detection unit 50 instead of the magnetic field strength detection unit 10, and thus the current sensor described in the first embodiment. It is different from 1.

The first resistance elements 51A and 51B and the second resistance elements 52A and 52B in the magnetic field strength detection unit 50 shown in FIG. 12 are multilayer film GMR elements having the same film configuration and the same dimensions. The characteristics are shown. However, the magnetic shields 53A and 53B are provided between the second resistance elements 52A and 52B and the current line 5 to be measured, and the detection sensitivity of the second resistance elements 52A and 52B is the first resistance elements 51A and 51B. Is lower than.

The magnetic shield 53 reduces the magnetic field strength within a predetermined range. Therefore, by providing the magnetic shield 53, the detection sensitivity to the magnetic field to be measured induced from the current line 5 to be measured becomes low. Therefore, the detection sensitivity of the second resistance element 52 is lower than the detection sensitivity of the first resistance element 51. Compared to the second embodiment shown in FIG. 9, the use of the magnetic shield 53 enables the current sensor 3 to be made compact.

FIG. 13 is a graph showing the RH waveforms of the first resistance element 51 and the second resistance element 52 that form the magnetic detection device that forms the current sensor 3. The solid line shown in FIG. 13 shows the change of the resistance value with respect to the change of the external magnetic field H of the first resistance element 51 not provided with the magnetic shield 53 between the measured current line 5 and the broken line, the measured current line. 5 shows the change of the resistance value of the second resistance element 52 having the magnetic shield 53 between the resistance value and the external magnetic field H. The broken line graph in FIG. 13 shows that the resistance value does not change in the vicinity of ±430 (mT), which means that the magnetic shield 53 is magnetically saturated in the vicinity of the numerical value.

In FIG. 14, the first differential output voltage (VoutA-VoutB) is shown by a solid line, and the second differential output voltage (VoutB-VoutA) is shown by a one-dot chain line. In the switch unit 30 shown in FIG. 12, the first differential output voltage (VoutA-VoutB) and the second differential output voltage (VoutB-VoutA) are changed according to the change in the polarity of the detection output from the magnetic field direction detection unit 20. ) And switch. As a result, the detection output voltage (Vout) of the magnetic detection device is such that the thick chain line shown in FIG. 14 and the thick solid line are continuous. That is, in the measurable range shown in FIG. 14, as the single detection output voltage (Vout), the change of the external magnetic field, for example, the change of the direction of the measured magnetic field according to the change of the direction of the current line 5 to be measured in the current sensor 1. It is possible to obtain outputs with different polarities.

In the present embodiment, the magnetic shield 53 is installed only on the second resistance element 52, but different magnetic shields are installed on the first resistance element 51 and the second resistance element 52, and the first resistance element 52 is installed. The sensitivity of the element 51 and the second resistance element 52 may be different.

<Fourth Embodiment>
FIG. 15 is a circuit block diagram of a magnetic detection device used in the current sensor 4 according to the fourth embodiment of the present invention. As shown in the figure, the magnetic sensor used in the current sensor 4 includes a magnetic field strength detection unit 60 in place of the magnetic field strength detection unit 10 in that the current sensor described in the first embodiment is used. It is different from 1.

The first resistance elements 61A and 61B and the second resistance elements 62A and 62B of the magnetic field strength detection unit 60 shown in FIG. 15 are all multilayer GMR elements and have the same film configuration and the same size. However, the first resistance elements 61A and 61B and the second resistance elements 62A and 62B have different installation directions with respect to the magnetic field direction from the measured current line 5 which is the magnetic field generation source.

In the multilayer GMR element of the first resistance element 61 and the second resistance element 62 shown in FIG. 2, the Y direction is the stacking direction of the layers and the thickness direction of the layers. The XZ plane is parallel to the planes of the ferromagnetic layers 112 and the nonmagnetic material layer 113. The area of each layer in the XZ plane is sufficiently larger than the area (cross-sectional area) in the XY plane shown in FIG.

In the first resistance element 61, the plane of each layer parallel to the XZ plane is parallel to the magnetic field H generated when a current flows in the measured current line 5 perpendicularly to the paper surface of FIG. It is installed so that. On the other hand, the second resistance element 62 is installed such that the surface of each layer parallel to the XY plane is parallel to the magnetic field H. Therefore, in the second resistance element 62, when the external magnetic field H changes, the magnetization of the ferromagnetic layer 112 (see FIG. 2) tends to change in the film thickness direction (Y direction), so that the demagnetizing field is changed. It works, and the detection sensitivity of the element becomes extremely low. Therefore, the detection sensitivity of the second resistance element 62 can be made substantially different from that of the first resistance element 61. Therefore, by configuring the block circuit shown in FIG. Change) can be detected.

FIG. 16 is an explanatory diagram showing a modified example of the film configuration of the multilayer film GMR element included in the magnetic detection devices according to the above-described first to fourth embodiments. As shown in the figure, in the multilayer GMR element 70, the antiferromagnetic layer 116 is laminated on the outermost ferromagnetic layer 112 of the ferromagnetic layers 112. The antiferromagnetic layer 116 may be provided between the underlayer 111 and the lowermost ferromagnetic layer 112. That is, the antiferromagnetic layer 116 is provided by being laminated on one or both of the ferromagnetic layers 112 located in the outermost layer of the multilayer structure layer 114.

The antiferromagnetic layer 116 includes an x-Mn alloy (x, manganese alloy, x=Pt, Ir, Ru, Rh, Pd, Fe, Ni), an x-Cr alloy (x, chromium alloy, x=Al, Pt, Mn) and x-O (oxide of x, x=Fe, Co, Ni) and the like can be used. Among these, PtMn alloys (platinum-manganese alloys) and IrMn alloys (iridium-manganese alloys) are preferable.

In the present embodiment, the antiferromagnetic layer 116 made of a PtMn alloy is annealed and ordered to cause exchange coupling with the ferromagnetic layer 112 (interface). This exchange coupling improves the strong magnetic field resistance of the ferromagnetic layer 112.

(Example 1)
A resistance element (see FIG. 2) of the magnetic detection device having the following film structure was manufactured. The value in parentheses indicates the film thickness (Å).
Substrate/Underlayer 111:NiFe-36Cr(42)/Multilayer structure layer 114:[Ferromagnetic layer 112:90CoFe(20)/Nonmagnetic material layer 113:Cu(11)]×15/Protective layer 115:Ta(50 )
Rs=4.6Ω/□, stripe line length=150 μm, stripe width=0.8 μm, number of stripes=13, R ₀ =11213Ω

That is, the multilayer GMR element is formed linearly with the X direction shown in FIG. 2 oriented in the line length direction of the stripe and the dimension in the Z direction oriented in the stripe width direction. The multilayer GMR element in the first resistance element 11 is formed in a zigzag so-called meander pattern in the XZ plane, with the X direction being the stripe length direction. The number of stripes is the number of stripes of the element in the meander pattern. R ₀ is the resistance value of the entire meander pattern.

1, 2, 3, 4 Current sensor 5 Current lines to be measured 10, 40, 50, 60 Magnetic field intensity detection units 11A, 11B, 41A, 41B, 51A, 51B, 61A, 61B First resistance element (multilayer film GMR element) )
12A, 12B Second resistance element (fixed resistance element)
42A, 42B, 52A, 52B, 62A, 62B Second resistance element (multilayer film GMR element)
13 1st end 14 2nd end 15A, 15B, sensor output end 16A, 16B Differential amplifier 20 Magnetic field direction detection part 21A, 21B 3rd resistance element 22A, 22B 4th resistance element 23 Comparator 30 Switch part 53A, 53B Magnetic shield 70 Multilayer GMR element 111 Underlayer 112 Ferromagnetic layer 113 Nonmagnetic material layer 114 Multilayer structure layer 115 Protective layer 116 Antiferromagnetic layer A First series circuit B Second series circuit Vdd First potential source GND Second potential source d1, d2 Distance H Magnetic field

Claims (9)

A magnetic field strength detection unit, a magnetic field direction detection unit, and a switch unit are provided,
The magnetic field strength detection unit,
A first resistance element, which is a multi-layer GMR element in which ferromagnetic layers and non-magnetic material layers are alternately laminated, and a multi-layer in which detection sensitivity to a magnetic field from the same magnetic field generation source is different from that of the first resistance element. A first series circuit in which a film GMR element or a second resistance element which is a fixed resistance is connected in series;
A second series circuit in which the second resistance element and the first resistance element are connected in series,
The same voltage is applied to the first series circuit and the second series circuit,
A first differential output voltage between the midpoint outputs of the first resistance element and the second resistance element in the first series circuit and the second series circuit; and the first differential output voltage. And a second differential output voltage obtained by inverting the polarity of the output voltage is output to the switch unit,
In the magnetic field direction detection unit,
A detection output whose polarity changes according to the direction of the magnetic field is output to the switch unit,
The switch unit selects either the first differential output voltage or the second differential output voltage as a detection output voltage according to the polarity of the detection output from the magnetic field direction detection unit. Magnetic detection device characterized by. The magnetic detection device according to claim 1, wherein the second resistance element is a multi-layer GMR element having the same film configuration and the same size as the first resistance element. The magnetic detection device according to claim 2, wherein the first resistance element and the second resistance element have different distances to the same magnetic field generation source. The magnetic detection device according to claim 2, wherein the first resistance element and the second resistance element are different in installation of a magnetic shield between the same magnetic field generation source. The magnetic detection device according to claim 2, wherein the first resistance element and the second resistance element have different installation directions with respect to the magnetic field of the same magnetic field generation source. In the first resistance element, the film surface direction of the multilayer film GMR element is provided in parallel with the magnetic field of the magnetic field generation source,
The magnetic detection device according to claim 5 , wherein the second resistance element is provided so that a film thickness direction of the multilayer film GMR element is parallel to a magnetic field of a magnetic field generation source. 7. The multi-layered film GMR element according to claim 1, wherein an antiferromagnetic layer is provided in contact with one or both of the ferromagnetic layers located at the outermost layer. Magnetic detection device. 8. The magnetic detection device according to claim 1, wherein the magnetic field direction detection unit includes a bridge circuit having a spin valve type GMR element. The magnetic detection device according to claim 1, wherein the magnetic field direction detection unit includes a bridge circuit having a Hall element.

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