JP5641276B2 - Current sensor - Google Patents

Description

  The present invention relates to a current sensor that measures a current to be measured in the vicinity of a U-shaped portion of a U-shaped primary conductor to which the current to be measured is applied.

  Conventionally, as a method for measuring a current to be measured in a non-contact manner, there is generally a method using a magnetic core. In a current sensor using a magnetic core, the magnetic core is installed so as to surround a conductor through which a current to be measured flows, and a magnetic circuit is formed together with a gap portion provided in the magnetic core. The magnitude of the current to be measured is measured in a non-contact manner by measuring the magnitude of the magnetic flux generated in the magnetic circuit by the current to be measured through the magnetoelectric conversion element installed in the gap portion.

  On the other hand, current sensors that do not use a magnetic core have been proposed for the purpose of miniaturization, weight reduction, and high accuracy. As a current sensor that uses a conventional magnetoelectric conversion element and does not use a magnetic core, a bridge circuit made up of a plurality of magnetoresistive elements is arranged on a U-shaped primary conductor with a predetermined interval through an insulator. There are some (see, for example, Patent Document 1).

JP 8-21138

Terunobu Miyazaki et al .: Journal of Japan Society of Applied Magnetics, Vol. 14, no. 2 (1990) 221 Nakamura, et al .: Journal of the Japan Institute of Metals, Vol. 56, no. 7 (1992) 849

  The primary conductor of the current sensor or magnetic sensor disclosed in Patent Document 1 has a symmetrical U-shaped structure, and a reverse magnetic field is applied to each of the left and right half bridges of a bridge circuit composed of magnetoresistive elements. And has the advantage of removing a uniform external magnetic field. However, the primary conductors have a symmetrical U-shaped structure, and the primary conductors located on both sides of the magnetoresistive effect element are fixed in a straight line shape. Because of the configuration in which a magnetic field is applied from one direction that is substantially perpendicular, a shift occurs in the installation position of the primary conductor in the manufacturing process of the current sensor. In other words, there is a possibility that a discontinuous error is superimposed on the output of the current sensor, that is, the output of the current sensor. This phenomenon is disclosed in Non-Patent Document 1, and in FIG. 3 in the document, the magnetoresistive curve is asymmetrical even if it is slightly deviated from 90 °, which is a perpendicular direction, to + 2 ° or −2 °. History is shown. In this document, it is considered that the asymmetry of the magnetoresistance effect curve of the thin film by vapor deposition is due to the unidirectional magnetic anisotropy associated with the magnetic nonuniformity of the sample. It is difficult to avoid magnetic non-uniformity of the sample in the manufacture of the magnetoresistive effect element, and it is desirable to apply a magnetic field from a direction perpendicular to reduce the discontinuous error. In the manufacturing process, it is difficult to accurately control the installation position of the primary conductor with respect to the longitudinal direction of the magnetoresistive effect element, and there is no means for adjusting the direction of the magnetic field applied from the primary conductor. There is a problem in that the degree of discontinuous error varies depending on the sensor, and as a result, the performance of the current sensor varies.

  In Non-Patent Document 2, attention is paid to the direction of shape magnetic anisotropy and the direction of induced magnetic anisotropy, and the history that occurs in the left-right asymmetry of the magnetoresistance curve is mentioned. When the inclination of the induced magnetic anisotropy with respect to the major axis direction of the magnetoresistive element, that is, the shape magnetic anisotropy direction is θ, the influence of the discontinuous change in the response of the magnetoresistive element on the magnetoresistive response curve is minimized. The direction of the magnetic field increases from the perpendicular direction as θ increases. Thus, depending on the value of θ, there is a certain magnetic field direction (in this document, within a few degrees from the perpendicular direction) that reduces discontinuous errors. In order to reduce the discontinuous error, it is desirable to adjust the direction of the magnetic field applied from the primary conductor by at least several degrees. There is a problem that a phenomenon in which the degree of discontinuous error differs occurs, and as a result, the performance of the current sensor varies.

  The present invention has been made in order to solve the above-described problems. By providing a means for adjusting the direction of the magnetic field applied from the primary conductor to the magnetoresistive element, there is a problem in the response of the magnetoresistive element. It is an object of the present invention to provide a current sensor that can reduce continuous errors and suppress variation in performance.

  The current sensor according to the present invention includes four magnetoresistive elements on the installation board, the first half bridge circuit is arranged in one area separated from the center line of the installation board, and the other area. Current detection device having a second half-bridge circuit disposed therein and at least one primary conductor having a U-shape, and the center line of the installation board and the symmetry axis of the U-shape of the primary conductor substantially coincide with each other The at least one current detection device is disposed in the vicinity of the U-shaped portion, and the installation board is disposed with respect to the primary conductor with the center point of the installation board located on the center line of the installation board as a substantially midpoint. It has a rotatable structure.

  In addition, the current sensor according to the present invention is capable of rotating the primary conductor relative to the current detection device with the U-shaped bottom of the U-shaped symmetrical axis of the primary conductor or a through hole provided in the vicinity thereof as a base point. It takes a simple structure.

  In addition, the current sensor according to the present invention has a structure in which an arcuate counterbore portion is provided on the upper surface, the lower surface, or both surfaces of a U-shaped primary conductor, and a sensor substrate is connected via the counterbore portion. Is.

  In addition, the current sensor according to the present invention includes four magnetoresistive elements on the installation board, the first half-bridge circuit is arranged in one area separated from the center line of the installation board, and the other A current sensing device in which a second half-bridge circuit is disposed in the region, at least one U-shaped primary conductor, and at least two bias magnetic field generators, wherein the current sensing device includes a plurality of the current sensing devices. In the region sandwiched by the bias magnetic field generation unit, and arranged so that the center line of the installation substrate of the current detection device and the U-shaped symmetry axis of the primary conductor substantially coincide with each other, On the other hand, the current detection device has a structure that can move in a direction perpendicular to the symmetry axis of the U-shaped portion.

  The current sensor according to the present invention has a structure in which at least one primary conductor is movable in a direction perpendicular to the symmetry axis of the U-shaped portion of the primary conductor.

According to the current sensor of the present invention, the first half-bridge circuit is arranged in one region divided with respect to the center line on the installation board by four magnetoresistive elements on one installation board. The second half-bridge circuit is arranged in the other region, and a magnetic field in the opposite direction is applied to each half-bridge circuit, so that there is an effect of removing a uniform external magnetic field.
In addition, the direction of the magnetic field applied in the plane of the magnetoresistive effect element can be varied, and accordingly, it can be adjusted so as to reduce discontinuous errors in the response of the magnetoresistive effect element. This has the effect of reducing the output error.

  Further, according to the current sensor of the present invention, it is possible to obtain means for adjusting the direction of the magnetic field applied to the magnetoresistive effect element only by linear movement of the primary conductor, and accordingly, a discontinuous error in the response of the magnetoresistive effect element. Therefore, there is an effect of downsizing and cost reduction.

It is a top view of the current sensor by Embodiment 1 of this invention. It is a perspective view which shows the primary conductor of the current sensor by Embodiment 1 of this invention. It is sectional drawing of the current sensor by Embodiment 1 of this invention. It is a magnetic field vector and its decomposition | disassembly vector of the electric current sensor by Embodiment 1 of this invention near the electric current detection device part shown in FIG. It is a top view which shows the current detection device part of the current sensor by Embodiment 1 of this invention. It is a structure schematic diagram which shows the current detection device part of the current sensor by Embodiment 1 of this invention. It is a top view which shows the direction which applies a to-be-measured current at the time of adjustment of the current sensor by Embodiment 1 of this invention. It is a top view which shows another direction which applies a to-be-measured current at the time of adjustment of the current sensor by Embodiment 1 of this invention. It is a block diagram which has arrange | positioned the compensation electrically conductive line of the current sensor by Embodiment 1 of this invention. It is a magnetic field vector of the current detection device part vicinity when the different primary conductor of the current sensor by Embodiment 1 of this invention is used, and its decomposition vector. It is a top view of the current sensor by Embodiment 2 of this invention. It is a perspective view which shows the primary conductor of the current sensor by Embodiment 2 of this invention. It is a top view of the current sensor by Embodiment 3 of this invention. It is a perspective view which shows the primary conductor of the current sensor by Embodiment 3 of this invention. It is a top view of the current sensor by Embodiment 4 of this invention. It is sectional drawing of the current sensor by Embodiment 4 of this invention.

Embodiment 1 FIG.
1 is a plan view of a current sensor according to Embodiment 1 of the present invention, FIG. 2 is a perspective view showing only a primary conductor of FIG. 1, and FIG. 3 is a cross-sectional view taken along the line AA ′ (XZ plane) in FIG. It is sectional drawing which shows a part. In the figure, the current sensor 1 includes a sensor substrate 2 having a current detection device unit 7 and a sensor circuit unit 9, and a primary conductor 3.
The primary conductor 3 in this Embodiment 1 is produced from the metal plate which has electrical conductivity. The shape of the primary conductor 3 is U-shaped when viewed from the Z direction, the U-shaped portion 4 showing the U-shape, the U-shaped bottom portion 5 connecting the symmetrical conductor portions, and the connection extending in the in-plane direction. The conductor portion 6 is used. The surface of the primary conductor 3 in the U-shaped part 4 has an arcuate counterbore part 8, and the sensor substrate 2 is installed on the counterbore part 8.
First, the configuration of the current detection device unit 7 will be described.
FIG. 5 shows a plan view of the current detection device unit 7, which is divided into two regions on the installation substrate 17 by the center line 11 of the installation substrate 17. In each region, the magnetoresistive effect elements 14 a and 14 b, magnetic Resistive effect elements 14c and 14d are arranged equally in line symmetry. Here, the magnetic sensitive direction of the magnetoresistive effect element 14 is the X direction, and the longitudinal direction is the Y direction. The four magnetoresistive effect elements 14a to 14d are arranged in parallel to each other with respect to the center line 11 of the installation substrate 17, and the magnetoresistive effect elements 14a and 14d have a resistance value corresponding to an increase in the magnetic field in the opposite direction. The magnetoresistive effect elements 14b and 14c have a magnetoresistive effect characteristic in which the resistance value decreases together with an increase in the magnetic field in the opposite direction. Although not shown, a barber pole electrode structure is formed on the magnetoresistive element. The four magnetoresistive effect elements 14 are each configured as one, but a plurality of magnetoresistive effect elements may be connected in a crank shape to increase the line length. Further, it may be configured symmetrically with respect to the center point on the center line 11. The connection current line 15 forms a bridge circuit 18 by connecting the four magnetoresistive effect elements 14, and the connection area 16 is used as an input / output terminal portion of the bridge circuit 18.

FIG. 6 is a schematic configuration diagram showing the current detection device 7 of the current sensor 1 according to Embodiment 1 of the present invention. In FIG. 6, by connecting the four magnetoresistive effect elements 14 with the connection current line 15, FIG. A half-bridge circuit (first half-bridge circuit) 19a comprising a series connection of magnetoresistive elements 14a and 14b, and a half-bridge circuit (second half-bridge circuit) 19b comprising a series connection of magnetoresistive elements 14c and 14d. A bridge circuit 18 composed of parallel connections is configured.
The connection area (first connection area) 16a is connected to the connection current line 15 between the magnetoresistive effect elements 14a and 14c of the bridge circuit 18, and the other connection area (second connection area) 16b is the bridge circuit. 18 is connected to the connection current line 15 between the magnetoresistive effect elements 14b and 14d, and a voltage is supplied to the bridge circuit 18 from the connection areas 16a and 16b. The connection area (third connection area) 16c is connected to the connection current line 15 between the magnetoresistive elements 14a and 14b of the bridge circuit 18, and the other connection area (fourth connection area) 16d is the bridge circuit. It is connected to a connection current line 15 between 18 magnetoresistive elements 14c and 14d, and the output voltage of the bridge circuit 18 is detected from the connection areas 16c and 16d.

  Although not shown in FIGS. 5 and 6, the compensation conductive line 20 is disposed above or below the four magnetoresistive elements 14 a to 14 d on the installation substrate 17, or both through an insulating layer. A magnetic balance type configuration may be employed in which a current that cancels the magnetic field generated in the vicinity of the four magnetoresistive elements 14 is supplied to the compensation conductive lines 20 based on the output voltage of the bridge circuit 18.

Next, the overall configuration of the current sensor 1 will be described.
As shown in FIGS. 1 and 2, the shape of the primary conductor 3 is U-shaped when viewed from the Z direction, and an arcuate counterbore portion 8 is provided on the conductor of the U-shape portion 4. Since the sensor substrate 2 is installed via the counterbore part 8 and the sensor substrate 2 is rotationally moved along the counterbore part 8 at the time of adjustment described later, the counterbore part 8 serves as a guide when the sensor board 2 is moved. In the figure shown in the first embodiment, both side portions of the U-shaped bottom portion 5 are formed in a right-angled shape, but the current detection device portion 7 is stabilized from the primary conductor located on both sides of the U-shaped portion 4. However, the shape may be rounded or the like as long as the magnetic field in the reverse direction is applied, and the shape is not limited thereto. However, in order to stably apply the magnetic field in the reverse direction, the U-shaped portion 4 has at least a current. It is desirable that the detection device unit 7 is symmetrical in the vicinity of the detection device unit 7.
As shown in FIG. 1, the sensor substrate 2 has a counterbore portion 8 so that the axis of symmetry indicated by the one-dot chain line of the primary conductor 3 having the U-shaped portion 4 and the center line 11 of the current detection device portion 7 substantially coincide. First, it is installed above the primary conductor 3. In the present embodiment, an example is shown in which the current detection device 7 is installed on the upper surface side of the sensor substrate 2, and the installation position is not limited to the upper surface, but the electric field shield provided in the inner layer of the sensor substrate 2 described later. In order to use the layer 12 effectively, it is desirable to install it on the upper surface. The current detection device unit 7 is not only mechanically installed but also electrically connected using wire bonding, bumps, or the like so as to be electrically connected to a sensor circuit unit 9 described later. The installation position (in particular, the Z direction) of the sensor substrate 2 including the current detection device unit 7 is determined according to the magnetic field to be applied to the magnetoresistive effect element 14, that is, the magnitude of the current to be measured. Since the applied magnetic field in the magnetosensitive direction is 0 at the position that is the center of the conductor 3 (broken line O in FIG. 3), it is preferable that the conductor 3 be installed shifted from the center. The sensor substrate 2 is installed according to the determined position. The cross-sectional area of the primary conductor 3 is determined according to the measured current value to be applied. Such a primary conductor 3 is produced, for example, by punching from a metal plate material such as copper having good electrical conductivity, but the production method is not limited to this. For example, when the plate thickness is increased, You may produce by casting etc.
Although only shown in FIG. 1, the sensor circuit unit 9 is disposed on the sensor substrate 2 together with the current detection device unit 7. The sensor circuit unit 9 supplies the voltage of the bridge circuit 18 to the connection areas 16a and 16b of the current detection device unit 7 and outputs the output voltage of the bridge circuit 18 with appropriate amplification. The terminal 10 is used to electrically connect the input / output terminals.
The sensor substrate 2 and the primary conductor 3 are fixed using an adhesive, a mounting member, or the like, although not particularly illustrated, after adjustment described later. The mounting member is not particularly limited in material, but is preferably non-magnetic and less deteriorated with time, and may be entirely or partially resin-molded in order to increase the effect of insulation and pressure resistance.
As shown in the cross-sectional view of FIG. 3, the electric field shield layer 12 having conductivity is provided on the inner layer of the sensor substrate 2. The electric field shield layer 12 is for removing or reducing electric field noise applied to the magnetoresistive effect element 14 and the sensor circuit unit 9 from the outside as noise that degrades the performance as a current sensor. It is necessary to install between the element 14 or the sensor circuit unit 9 and the primary conductor 3, and it is desirable to install the magnetoresistive effect element 14 or the sensor circuit unit 9 if possible. The material of the electric field shield layer 12 only needs to have conductivity. For example, copper, aluminum or the like can be considered, and the electric field shield layer 12 is connected to an electrical ground provided on the sensor substrate 2. As a form of installation, for example, a ground layer may be provided on at least one of the inner layers of the multilayer substrate.

Here, the adjustment method for reducing the discontinuous error in the response of the magnetoresistive effect element will be described in detail.
When the inclination θ of the induced magnetic anisotropy with respect to the major axis direction of the magnetoresistive effect element, that is, the shape magnetic anisotropy direction is 0, the 90 ° direction that is perpendicular to the major axis direction of the magnetoresistive effect element If a magnetic field is applied from, discontinuous errors can be reduced. In addition, if the gradient θ of the induced magnetic anisotropy relative to the direction of the shape magnetic anisotropy is not 0, discontinuous errors can be reduced by applying a magnetic field from one direction within a few degrees from the perpendicular direction. it can. If the gradient θ of the induced magnetic anisotropy with respect to the direction of the shape magnetic anisotropy is known, the sensor substrate 2 is moved along the counterbore part 8 so as to be an applied magnetic field direction that can naturally reduce discontinuous errors. Rotate and fix. However, it is difficult to completely fix the gradient θ of the induced magnetic anisotropy with respect to the direction of the shape magnetic anisotropy to 0 or a constant value in the manufacture of the magnetoresistive effect element by vapor deposition or the like. In many cases, the inclination θ of the induced magnetic anisotropy with respect to the direction of the shape magnetic anisotropy varies depending on the resistive element.
Therefore, it is necessary to adjust to reduce discontinuous errors in the response of the magnetoresistive effect element. First, as shown in FIG. 1, the sensor substrate 2 is installed so that the symmetry axis indicated by the one-dot chain line of the primary conductor 3 having the U-shaped portion 4 and the center line 11 of the current detection device portion 7 substantially coincide. In this state, the magnetoresistive response curve of each magnetoresistive effect element is acquired. Since a current sensor is formed here, a current to be measured is applied from the primary conductor 3b side as shown by an arrow in FIG. The current value is varied, and the result of the magnetoresistive response of each magnetoresistive effect element is obtained as the output of the current sensor via the external terminal 10. Next, as shown by the arrows in FIG. 8, the current to be measured is applied from the primary conductor 3a side, the current value is varied, and the magnetoresistive response of each magnetoresistive element is output as the output of the current sensor via the external terminal 10. Get the result. In this way, if there is a difference in the absolute value of the current sensor output obtained by reversing the direction of the current to be measured, it can be said that a discontinuous error has been confirmed. At that time, the sensor substrate 2 is rotated along the counterbore part 8 with the center point of the sensor substrate 2 as a base point, the above measurement is repeated, and the absolute current sensor output obtained by reversing the direction of the current to be measured is obtained. The measurement is stopped when the installation position of the sensor substrate 2 that does not cause a difference in value is obtained, and the sensor substrate 2 is fixed. By performing such adjustment, it becomes possible to reliably reduce discontinuous errors in the response of the magnetoresistive effect element.
Note that if the measured current value for which a discontinuous error can be remarkably confirmed is known, the measured current value may be fixed and adjusted to a certain value without changing it, and as a result, the adjustment process is simplified. The effect is realized.
Further, since the rotation angle of the sensor board 2 is about several degrees, the counterbore part 8 is limited only to a part where the sensor board 2 can move about several degrees without departing from the counterbore part 8 provided on the primary conductor 3. May be provided.

Next, the operation of the current sensor 1 will be described with reference to FIGS. 3, 4, and 5.
When a current to be measured is applied to the primary conductor 3, for example, a left-rotating magnetic field is applied to the first primary conductor portion 3a with respect to the direction of the current as indicated by a broken line in FIG. 3, and to the second primary conductor portion 3b. As shown by the broken line in FIG. 3, a clockwise magnetic field is generated according to the magnitude of the current to be measured. In the figure, the generated magnetic field is shown by two magnetic flux lines for each primary conductor for simplicity. As a result, when the current detection device unit 7 is installed at the position shown in FIG. 3, the magnetic field vector 13 a shown in FIG. 4 is applied to the magnetoresistive effect elements 14 a and 14 b located on the left side of the current detection device unit 7. The magnetic field vector 13b is applied to the magnetoresistive elements 14c and 14d located on the right side. Therefore, the decomposition vector 13ax is added to the magnetosensitive direction (X-axis direction) of the magnetoresistive effect elements 14a and 14b, and the decomposition vector 13bx is added to the magnetic sensitive direction (X-axis direction) of the magnetoresistive effect elements 14c and 14d. . That is, a magnetic field is applied to the magnetoresistive effect elements 14a and 14b shown in FIG. 5 on the XY plane of the current detection device unit 7 in the direction of the left side of the drawing with respect to the center line 11, and the magnetoresistive effect elements 14c and 14d have A magnetic field is applied in the direction of the right side of the drawing from the center line 11.

The magnetoresistive elements 14a and 14d both have a magnetoresistive effect characteristic in which the resistance value increases as the magnetic field increases and the resistance value decreases as the magnetic field decreases. In contrast, the elements 14b and 14c are configured to have magnetoresistance effect characteristics in which the resistance value decreases as the magnetic field increases and the resistance value increases as the magnetic field decreases.
Therefore, as the current flowing through the primary conductor 3 increases, the resistance values of the magnetoresistive elements 14a and 14d increase, and the resistance values of the magnetoresistive elements 14b and 14c decrease, and the current flowing through the primary conductor 3 decreases. Accordingly, the resistance values of the magnetoresistive effect elements 14a and 14d decrease and the resistance values of the magnetoresistive effect elements 14b and 14c increase. Thus, the balance of the bridge circuit 18 is lost in accordance with the magnitude of the current to be measured applied to the primary conductor 3, and this becomes the output of the bridge circuit 18 of the current detection device unit 7.

Further, the operation of the current sensor 1 will be described in the case where the compensation conductive line 20 is provided. FIG. 9 shows a schematic configuration of the current detection device unit 7 and the sensor circuit unit 9 in which the compensation conductive wire 20 is arranged.
The balance of the bridge circuit 18 is lost depending on the magnitude of the current to be measured applied to the primary conductor 3. At this time, in the amplification circuit unit (for example, the operational amplifier 21) installed in the sensor circuit unit 9, the vicinity of the magnetoresistive effect elements 14a to 14d based on the output voltage detected from the connection areas 16c and 16d of the current detection device unit 7. A current (control current) that cancels out the magnetic field generated in the compensation conductive line 20 is supplied. Specifically, the magnitude of the control current is adjusted so that the output voltage of the connection areas 16c and 16d becomes zero. The compensation conductive line 20 cancels out the magnetic field generated in the vicinity of the four magnetoresistive elements 14a to 14d according to the magnitude of the control current, that is, the magnetic field according to the magnitude of the current to be measured applied to the primary conductor 3. Generate a magnetic field.
Therefore, the collapse of the balance of the bridge circuit 18 according to the magnitude of the current to be measured applied to the primary conductor 3 can be repaired by the control current supplied from the sensor circuit unit 9. Therefore, the magnitude of the control current supplied from the sensor circuit unit 9 can be detected as a value correlated with the magnitude of the current to be measured applied to the primary conductor 3.
The external magnetic field (disturbance magnetic field) generated outside the primary conductor 3 has an in-phase influence on the magnetoresistive effect elements 14a and 14b and the magnetoresistive effect elements 14c and 14d (the left and right half bridge circuits 19 of the bridge circuit 18). Therefore, it is offset and does not affect the measurement accuracy.

Finally, the details of the primary conductor 3 will be supplemented. In the diagram shown in the first embodiment, the outer peripheral corner portions on both sides of the U-shaped bottom portion 5 of the primary conductor 3 are configured to have a right-angle shape without any particular processing, but the current to be measured is that of the primary conductor 3. Since it flows at the shortest distance from the connecting conductor portion 6 that becomes the input / output end of the primary conductor 3 in the inside, there is no problem even if the shape of the outer peripheral portion is not particularly limited. In order to reduce heat generation during application, that is, to dissipate heat, it is desirable that the material is not processed.
Further, in the present embodiment, the cross-sectional shape of the primary conductor 3 in the U-shaped portion 4 is a rectangle having a long axis in the X direction, but the cross-sectional shape of the primary conductor 3 in the U-shaped portion 4 is the out-of-plane direction (Z It is good also as a rectangle which has a long axis in (direction). In this case, as shown in FIG. 10, the magnitudes of the magnetic field vector 13x decomposed in the x-axis direction (magnetic sensing direction) and the magnetic field vector 13z decomposed in the z direction satisfy the relationship of 13x <13z. A lowered magnetic field is applied in the magnetic sensitive direction of the resistive element 14. If the cross-sectional shape of the primary conductor 3 is a rectangle having a long axis in the out-of-plane direction (Z direction), the magnetic field applied to the magnetoresistive effect element 14 is suppressed even when the current to be measured is large, and the output is saturated. It is possible to easily measure a large current without worrying about the above and without increasing the outer dimensions of the current sensor.

  As described above, according to the first embodiment, the first half-bridge circuit is arranged in one region divided with respect to the center line of the installation board by four magnetoresistive elements on the installation board. In addition, since the second half bridge circuit is arranged in the other region and a magnetic field in the opposite direction is applied to each half bridge circuit, there is an effect that a uniform external magnetic field can be removed.

  In addition, the direction of the magnetic field applied in the plane of the magnetoresistive effect element can be varied, and accordingly, it can be adjusted so as to reduce discontinuous errors in the response of the magnetoresistive effect element. This has the effect of reducing the output error.

  Further, since the electric field shield layer having conductivity is provided on the inner layer surface of the sensor substrate, it is possible to remove or reduce the electric field noise from the primary conductor and the outside, and to improve the measurement accuracy.

Embodiment 2. FIG.
11 is a plan view of a current sensor according to Embodiment 2 of the present invention, and FIG. 12 is a perspective view showing only the primary conductor of FIG. In the figure, the primary conductor 3 is made of a metal having electrical conductivity, and is composed of a U-shaped part 4, a U-shaped bottom part 5 and a connecting conductor part 6 in the same manner as in the first embodiment. Is provided with a through hole 22.
The second embodiment has a configuration in which the through hole 22 is provided in the primary conductor 3 shown in the first embodiment. In the first embodiment, the sensor substrate 2 is smaller than the primary conductor 3 in the example of the sensor substrate 2. In the second embodiment, a method for rotating and adjusting the primary conductor 3 in an example in which the sensor substrate 2 is larger than the primary conductor 3 is shown. In addition, the part which overlaps with another structure and operation | movement is abbreviate | omitted.

When the sensor substrate is smaller than the primary conductor, as shown in the first embodiment, the primary conductor 3 is provided with a counterbore portion 8, and the counterbore portion 8 serves as a guide for adjustment, facilitating the rotational movement of the sensor substrate 2. Yes. However, when the sensor substrate is larger than the primary conductor, the counterbore portion of the primary conductor does not function as a guide in the rotational movement of the sensor substrate.
In the present embodiment, a through hole 22 is provided in the U-shaped bottom portion 5 on the target axis of the primary conductor 3 without providing a counterbore portion in the primary conductor 3, and the primary conductor 3 is rotated with the through hole 22 as a base point. A moving structure was adopted. As an adjustment method for reducing the discontinuous error in the response of the magnetoresistive effect element, it is only necessary to change the direction of the magnetic field to be measured with respect to the major axis direction of the magnetoresistive effect element. Even if it is rotated, the same effect as that of the first embodiment in which the sensor substrate is rotated with respect to the primary conductor can be obtained.

An adjustment method for reducing discontinuous errors in the response of the magnetoresistive effect element according to the second embodiment of the present invention will be described. The primary conductor 3 is attached to the sensor substrate 2 using the through-hole 22 so that the axis of symmetry indicated by the one-dot chain line of the primary conductor 3 having the U-shaped portion 4 and the center line 11 of the current detection device portion 7 substantially coincide. Install. The installation method may be, for example, screwing or pinning using the through hole 22, and any installation means may be used as long as the primary conductor is temporarily held and the primary conductor 3 can be rotated and moved with the through hole 22 as a base point. In this state, a magnetoresistive response curve is acquired. Since the acquisition method is the same as that in the first embodiment, a description thereof will be omitted. If there is a difference in the absolute value of the obtained current sensor output, it can be said that a discontinuous error has been confirmed. In that case, the primary conductor 3 is rotated with the through hole 22 provided in the primary conductor 3 as a base point, the above measurement is repeated, and the absolute value of the current sensor output obtained by reversing the direction of the current to be measured is different. The measurement is stopped when the installation position of the primary conductor 3 is obtained, and the primary conductor 3 is fixed. By performing such adjustment, it becomes possible to reliably reduce discontinuous errors in the response of the magnetoresistive effect element.
Note that if the measured current value for which a discontinuous error can be remarkably confirmed is known, the measured current value may be fixed and adjusted to a certain value without changing it, and as a result, the adjustment process is simplified. The effect is realized.
Further, since the rotation angle of the primary conductor 3 is about several degrees, the primary conductor 3 does not deviate from the sensor substrate 2 and the size of the current sensor does not increase.

  As described above, according to the second embodiment, even when the sensor substrate 2 is larger than the primary conductor 3, the direction of the magnetic field applied in the plane of the magnetoresistive effect element by rotating the primary conductor 3 is changed. Since it is variable and can be adjusted so as to reduce the discontinuous error in the response of the magnetoresistive effect element, the output variation of the current sensor and the output error are reduced.

Embodiment 3 FIG.
13 is a plan view of a current sensor according to Embodiment 2 of the present invention, and FIG. 14 is a perspective view showing only the primary conductor of FIG. In the figure, the primary conductor 3 is made of a metal having electrical conductivity, and is composed of a U-shaped portion 4, a U-shaped bottom portion 5, and a connecting conductor portion 6 in the same manner as in the first embodiment. The arc shape is changed to a rectangle. In addition, a bias magnetic field generator 23 is newly provided on the sensor substrate 2.
The third embodiment has a configuration in which the bias magnetic field generator 23 is installed on the sensor substrate 2 shown in the first embodiment. In the first embodiment, the sensor substrate 2 is smaller than the primary conductor 3 in the example. In the third embodiment, the sensor board 2 is smaller than the primary conductor 3 as in the first embodiment, and the primary conductor 3 is moved linearly in the third embodiment. It shows the method of adjustment. In addition, the part which overlaps with another structure and operation | movement is abbreviate | omitted.

By installing the bias magnetic field generation unit in the vicinity of the current detection device unit, the internal magnetization direction of the magnetic metal film forming the magnetoresistive effect element can be maintained in the easy axis direction, and the Barkhausen jump and hysteresis can be suppressed. .
When the bias magnetic field generation unit 23 is not installed on the sensor substrate 2 as in the first or second embodiment, the magnetic field applied to the current detection device unit 7 is only due to the measured current flowing through the primary conductor 3. It becomes. Therefore, the means for changing the direction of the magnetic field has been limited to the rotational movement of the sensor substrate 2 having the current detection device unit 7 or the primary conductor 3.
However, when the bias magnetic field generation unit 23 is installed on the sensor substrate 2, the magnetic field applied to the current detection device unit 7 is caused by the measured current flowing through the primary conductor 3 and the bias magnetic field generation unit 23. It is a composition of things. Therefore, the means for changing the direction of the magnetic field is not limited to the rotational movement of the sensor substrate 2 having the current detection device unit 7 or the primary conductor 3, but the sensor substrate 2 along the counterbore portion 8 provided in a rectangular shape. A linear movement is also possible, and an effect equivalent to that of the first embodiment in which the sensor substrate 2 is rotated is obtained.

An adjustment method for reducing discontinuous errors in the response of the magnetoresistive effect element according to the third embodiment of the present invention will be described. The sensor substrate 2 is installed via the counterbore part 8 so that the axis of symmetry indicated by the one-dot chain line of the primary conductor 3 having the U-shaped part 4 and the center line 11 of the current detection device part 7 substantially coincide. In this state, a magnetoresistive response curve is acquired. Since the acquisition method is the same as that in the first embodiment, a description thereof will be omitted. If there is a difference in the absolute value of the obtained current sensor output, it can be said that a discontinuous error has been confirmed. At that time, the current sensor obtained by moving the sensor substrate 2 along the counterbore part 8 linearly in the X direction, for example, in the present embodiment, repeating the above measurement, and reversing the direction of the current to be measured. The measurement is stopped when the installation position of the sensor substrate 2 that does not cause a difference in the absolute value of the output is obtained, and the sensor substrate 2 is fixed. By performing such adjustment, it becomes possible to reliably reduce discontinuous errors in the response of the magnetoresistive effect element.
Note that if the measured current value for which a discontinuous error can be remarkably confirmed is known, the measured current value may be fixed and adjusted to a certain value without changing it, and as a result, the adjustment process is simplified. The effect is realized.
In addition, the moving distance of the sensor substrate 2 may have a balance with the primary conductor, but is approximately within a few millimeters. Therefore, the sensor substrate 2 does not deviate from the counterbore portion 8 provided in the primary conductor 3 and the sensor substrate 2 is about a few millimeters. The counterbore part 8 may be limited and provided only in the movable part.

  As described above, according to the third embodiment, the direction of the magnetic field applied in the plane of the magnetoresistive effect element can be changed by linearly moving the sensor substrate. Since adjustment is possible so that discontinuous errors in the response are reduced, there is an effect of reducing output variations and output errors of the current sensor.

  In addition, it is possible to obtain a means for adjusting the direction of the magnetic field applied to the magnetoresistive element only by linear movement of the primary conductor, and accordingly, the discontinuous error in the response of the magnetoresistive element can be reduced. In addition, there is an effect of cost reduction.

Embodiment 4 FIG.
15 is a plan view of a current sensor according to Embodiment 4 of the present invention, and FIG. 16 is a cross-sectional view taken along the center line 11 of FIG. FIG. 16 shows only a part of the configuration for simplicity. In the figure, a primary conductor holding portion 24 is newly provided on the back surface side of the sensor substrate 2 on which the primary conductor 3 is installed, compared to the embodiments described so far.
The fourth embodiment is a configuration in which the through hole 22 of the primary conductor 3 shown in the second embodiment is deleted, and a new bias magnetic field generation unit 23 and a primary conductor holding unit 24 are installed. In the third embodiment, Although the method of linearly moving and adjusting the sensor substrate 2 in an example in which the sensor substrate 2 is smaller than the primary conductor 3 has been described, in the fourth embodiment, the sensor substrate 2 is larger than the primary conductor 3 A method of adjusting the primary conductor 3 by linearly moving is shown. In addition, the part which overlaps with another structure and operation | movement is abbreviate | omitted.

When the sensor substrate is smaller than the primary conductor, as shown in the third embodiment, the primary conductor 3 is provided with a counterbore portion 8, and the counterbore portion 8 serves as a guide for adjustment, and the sensor substrate 2 can be easily moved linearly. I have to. However, when the sensor substrate is larger than the primary conductor, the counterbore portion of the primary conductor does not function as a guide for linear movement of the sensor substrate.
In the present embodiment, the primary conductor 3 is not provided with the counterbore part, but the primary conductor holding part 24 is provided on the back surface side of the sensor substrate 2 on which the primary conductor 3 is installed, and the primary conductor holding part 24 is used as a guide. 3 was configured to move linearly. As an adjustment method for reducing the discontinuous error in the response of the magnetoresistive effect element, it is only necessary to change the direction of the magnetic field to be measured with respect to the major axis direction of the magnetoresistive effect element. Even if it is moved linearly, the same effect as in the third embodiment in which the sensor substrate is linearly moved with respect to the primary conductor can be obtained.

An adjustment method for reducing discontinuous errors in the response of the magnetoresistive effect element according to the fourth embodiment of the present invention will be described. The primary conductor is connected to the sensor substrate 2 using the primary conductor holding part 24 so that the axis of symmetry indicated by the one-dot chain line of the primary conductor 3 having the U-shaped part 4 and the center line 11 of the current detection device part 7 substantially coincide. 3 is installed. The primary conductor holding portion 24 temporarily holds the primary conductor 3 and functions as a guide. If the primary conductor 3 can move linearly, the constituent material and the installation means are not limited, but it is preferably a non-magnetic material. . In this state, a magnetoresistive response curve is acquired. Since the acquisition method is the same as that in the first embodiment, a description thereof will be omitted. If there is a difference in the absolute value of the obtained current sensor output, it can be said that a discontinuous error has been confirmed. In that case, the primary conductor 3 is linearly moved using the primary conductor holding portion 24 as a guide, the above measurement is repeated, and the absolute value of the current sensor output obtained by reversing the direction of the current to be measured is different. When the installation position of the primary conductor 3 that does not occur is obtained, the measurement is stopped and the primary conductor 3 is fixed. By performing such adjustment, it becomes possible to reliably reduce discontinuous errors in the response of the magnetoresistive effect element.
Note that if the measured current value for which a discontinuous error can be remarkably confirmed is known, the measured current value may be fixed and adjusted to a certain value without changing it, and as a result, the adjustment process is simplified. The effect is realized.
In addition, the movement distance of the sensor board 2 may be balanced with the primary conductor, but is approximately within a few mm, so that the primary conductor 3 does not deviate from the sensor board 2 and the dimensions of the current sensor are increased. There is no.

  As described above, according to the fourth embodiment, even when the sensor substrate 2 is larger than the primary conductor 3, the magnetic field applied in the plane of the magnetoresistive effect element by moving the primary conductor 3 linearly. Since the direction can be varied and the adjustment can be made so as to reduce the discontinuous error in the response of the magnetoresistive effect element, the output variation of the current sensor and the output error are reduced.

  In addition, it is possible to obtain a means for adjusting the direction of the magnetic field applied to the magnetoresistive element only by linear movement of the primary conductor, and accordingly, the discontinuous error in the response of the magnetoresistive element can be reduced. In addition, there is an effect of cost reduction.

1 current sensor, 2 sensor board, 3 primary conductor, 4 U-shaped part, 5 U-shaped bottom part, 6 connecting conductor part, 7 current detection device part, 8 counterbore part, 9 sensor circuit part, 10 external terminal, 11 center line, 12 electric field shield layer, 13 magnetic field vector, 14 magnetoresistive effect element, 15 connection current line, 16 connection area, 17 installation board, 18 bridge circuit, 19 half bridge circuit, 20 compensation conductive line, 21 operational amplifier, 22 through hole, 23 Bias magnetic field generator, 24 Primary conductor holder

Claims (8)

First and fourth magnetoresistive elements disposed on an installation substrate and having a magnetoresistive effect characteristic in which a resistance value increases together with an increase in a magnetic field opposite to each other;
Second and third magnetoresistive elements disposed on the installation substrate and having a magnetoresistive effect characteristic in which a resistance value decreases together with an increase in the magnetic field in the opposite direction;
A first half-bridge circuit formed by the first and second magnetoresistive elements is connected to the first to fourth magnetoresistive elements disposed on the installation substrate, and the third and third magnetoresistive elements are connected. And a connection current line constituting a bridge circuit composed of a second half-bridge circuit by the magnetoresistive effect element, and the first half-bridge circuit in one region divided with respect to the center line of the installation board And a current sensing device in which the second half-bridge circuit is arranged in the other region, and a primary conductor having at least one U-shape,
At least one of the current detection devices is disposed in the vicinity of the U-shaped portion so that the center line of the installation substrate of the current detection device and the U-shaped symmetry axis of the primary conductor substantially coincide with each other. A current sensor, wherein the installation board is rotatable with respect to the primary conductor, with a center point of the installation board located on a center line of the installation board as a substantially middle point. The at least one primary conductor is capable of rotating the primary conductor with respect to the current detection device with a through hole provided in the vicinity of a U-shaped bottom portion on a U-shaped symmetrical axis as a base point. The current sensor according to claim 1. At least one of the current detection devices is installed on a sensor substrate together with a sensor circuit unit, and the sensor substrate is installed on the sensor substrate in at least one location near the U-shaped portion of the primary conductor. The center line of the device and the U-shaped symmetry axis of the primary conductor are arranged so as to substantially coincide with each other, and the center point of the current detection device located on the center line of the current detection device is set as a substantially middle point. The current sensor according to claim 1, wherein the current detection device or the sensor substrate is rotatable with respect to the primary conductor. At least one of the primary conductors has an arcuate counterbore on the upper surface, lower surface, or both surfaces of the U-shaped primary conductor, and the sensor substrate is connected via the counterbore. The current sensor according to claim 3. First and fourth magnetoresistive elements disposed on an installation substrate and having a magnetoresistive effect characteristic in which a resistance value increases together with an increase in a magnetic field opposite to each other;
Second and third magnetoresistive elements disposed on the installation substrate and having a magnetoresistive effect characteristic in which a resistance value decreases together with an increase in the magnetic field in the opposite direction;
A first half-bridge circuit formed by the first and second magnetoresistive elements is connected to the first to fourth magnetoresistive elements disposed on the installation substrate, and the third and third magnetoresistive elements are connected. And a connection current line constituting a bridge circuit composed of a second half-bridge circuit by the magnetoresistive effect element, and the first half-bridge circuit in one region divided with respect to the center line of the installation board And a current sensing device in which the second half-bridge circuit is disposed in the other region, at least one primary conductor having a U-shape, and at least two bias magnetic field generators,
The current detection device is in a region sandwiched between the plurality of bias magnetic field generation units, and a center line of the installation substrate of the current detection device and a U-shaped symmetry axis of the primary conductor substantially coincide with each other. At least one of the current detection devices is disposed in the vicinity of the U-shaped portion, and the current detection device is movable in a direction perpendicular to the symmetry axis of the U-shaped portion with respect to the primary conductor. A current sensor characterized by being. The current sensor according to claim 5, wherein at least one of the primary conductors is movable in a direction perpendicular to the symmetry axis of the U-shaped portion. At least one of the current detection devices is installed on a sensor substrate together with a sensor circuit unit and at least two of the bias magnetic field generation units, and the sensor substrate is disposed at least at one location near the U-shaped shape of the primary conductor. A center line of the current detection device installed on the substrate is arranged so that the symmetry axis of the U-shape is substantially coincident, and the current detection device or the sensor substrate is U-shaped with respect to the primary conductor. current sensor according to claim 5 or 6, characterized in that the perpendicular axis of symmetry of the mold shape is movable. At least one of the primary conductors is provided with a rectangular counterbore portion on the upper surface, the lower surface, or both surfaces of the U-shaped primary conductor, and the sensor substrate is connected via the counterbore portion. The current sensor according to claim 7.

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