JP2021085711A - Current detector - Google Patents

Abstract

To provide a current detector which is of a low loss type, and with which it is possible to increase the detectable amount of current.SOLUTION: Second wiring 22 is arranged on the other side in a third direction (z axis direction) from first wiring 21, with one and the other ends of each of the first wiring 21 and the second wiring 22 electrically connected to each other. A first magnetic field detection part 11 is, in a plan view of a plane that includes a first direction (x axis direction) and a second direction (y axis direction), arranged in a first second-direction area R211 between both end positions in second direction of a first outward path part 211, and in the plan view, arranged in a second second-direction area R221 between both end positions in second direction of a second outward path part 221. A second magnetic field detection part 12 is, in the plan view, arranged in a third second-direction area R212 between both end positions in second direction of a first homeward path part 212, and in the plan view, arranged in a fourth second-direction area R222 between both end positions in second direction of a second homeward path part 222.SELECTED DRAWING: Figure 11

Description

The present invention relates to a current detector.

Conventionally, as a current sensor for measuring the current flowing through the primary conductor, for example, one using a Hall element (Hall type) and one using a magnetoresistive effect element (MR type) are known (see, for example, Patent Document 1). ).

Japanese Unexamined Patent Publication No. 2011-39021

However, since the sensitivity of a Hall-type current sensor is generally low, it is necessary to bring the primary conductor and the Hall element close to each other, and it is necessary to provide the primary conductor inside the IC package of the current sensor. That is, it is necessary to use a retractable current sensor that draws a current inside the IC package. In the retractable current sensor, the resistance value of the primary conductor becomes large, and there is a possibility that the loss becomes large.

In view of the above situation, it is an object of the present invention to provide a current detection device having low loss and capable of increasing the amount of detectable current.

The current detection device according to one aspect of the present invention in order to achieve the above object
Assuming that the first direction, the second direction, and the third direction are orthogonal to each other,
A substrate that spreads in a plane including the first direction and the second direction and has a thickness in the third direction.
A magnetic field sensor arranged on the surface of the substrate on one side in the third direction,
With
The magnetic field sensor has a first magnetic field detection unit and a second magnetic field detection unit.
The substrate has a first wiring and a second wiring arranged on the other side of the first wiring in the third direction.
One end of the first wiring and one end of the second wiring are electrically connected to each other.
The other end of the first wiring and the other end of the second wiring are electrically connected.
The first wiring includes a first outward path portion extending in the second direction and a first return path portion extending in the second direction.
The first return path portion is arranged on one side in the first direction with respect to the first outward path portion, and is electrically connected to the first outward path portion.
The second wiring includes a second outward path portion extending in the second direction and a second return path portion extending in the second direction.
The second return path portion is arranged on one side of the first direction with respect to the second outward path portion, and is electrically connected to the second outward path portion.
The first magnetic field detection unit is arranged in a first second direction region between the positions of both ends of the second direction of the first outward path portion in a plan view of a plane including the first direction and the second direction. Moreover, in the plan view, it is arranged in the second second direction region between the positions of both ends of the second direction of the second outward path portion.
The second magnetic field detection unit is arranged in a third second direction region between the positions of both ends of the first return path portion in the second direction in the plan view, and the second return path portion is arranged in the plan view. It is configured to be arranged in the fourth second direction region between the positions at both ends of the second direction (first configuration).

Further, in the first configuration, the width of the first outward path portion and the width of the first return path portion are the same first width, and the width of the second outward path portion and the width of the second return path portion are the same. The second width is the same, and the first width and the second width may be different (second configuration).

Further, in the first or second configuration, the first directional distance between the first outward path portion and the first return path portion and the first between the second outward path portion and the second return path portion. The directional distance may be different (third configuration).

Further, in any one of the first to third configurations, at least one of the space between the first outward path portion and the first return path portion and the space between the second outward path portion and the second return path portion is , May be connected by a connecting portion via a load (fourth configuration).

Further, in order to achieve the above object, the current detection device according to another aspect of the present invention may be used.
Assuming that the first direction, the second direction, and the third direction are orthogonal to each other,
A substrate that spreads in a plane including the first direction and the second direction and has a thickness in the third direction.
A magnetic field sensor arranged on the surface of the substrate on one side in the third direction,
With
The magnetic field sensor has a first magnetic field detection unit and a second magnetic field detection unit.
The substrate has a first wiring and a second wiring.
One end of the first wiring and one end of the second wiring are electrically connected to each other.
The other end of the first wiring and the other end of the second wiring are electrically connected.
The first wiring includes a first outward path portion extending in the second direction and a first return path portion extending in the second direction.
The first return path portion is arranged on one side in the first direction with respect to the first outward path portion, and is electrically connected to the first outward path portion.
The first magnetic field detection unit is arranged in a first second direction region between the positions of both ends of the second direction of the first outbound route unit in a plan view of a plane including the first direction and the second direction.
The second magnetic field detection unit is arranged in the second second direction region between the positions of both ends of the second direction of the first return path unit in the plan view.
The second wiring has a configuration in which neither the first second direction region nor the second second direction region overlap in the plan view (fifth configuration).

Further, in the fifth configuration, the first outward path portion and the first return path portion may be connected by a connecting portion via a load (sixth configuration).

Further, in the fifth or sixth configuration, the first wiring and the second wiring may be included in the wiring of the same layer (seventh configuration).

Further, in any one of the first to seventh configurations, at least one of the width, thickness, path length, and material of the first wiring and the second wiring may be different (the first). 8 configuration).

Further, in any of the first to eighth configurations, the first magnetic field detection unit and the second magnetic field detection unit may detect a magnetic field using an MI (magnetic impedance) effect element (the first). 9 configuration).

According to the current detection device of the present invention, the loss is low and the amount of detectable current can be increased.

It is a top view which looked at the IC package of a magnetic field sensor from one side in the z-axis direction. It is a block block diagram of a magnetic field sensor. It is a waveform figure which shows an example of the drive current and the induced voltage generated in a pickup coil. It is a top view seen from one side in the z-axis direction of the current detection apparatus which concerns on a comparative example. FIG. 5 is a sectional view taken along the line AA in FIG. It is a top view for showing the y-axis direction region in FIG. It is a figure which shows an example of the correlation between the width of the outward path portion and the width of a return path portion, and the current detection sensitivity. It is a figure which shows an example of the correlation between the distance in the z-axis direction between a magnetic field sensor and a wiring, and a current detection sensitivity. It is a figure which shows an example of the correlation between the distance in the x-axis direction between an outward path part and a return path part, and a current detection sensitivity. It is a top view seen from one side in the z-axis direction of the current detection apparatus which concerns on 1st Embodiment. FIG. 8 is a cross-sectional view taken along the line AA in FIG. FIG. 8 is a cross-sectional view taken along the line BB in FIG. It is a top view for showing the y-axis direction region in 1st Embodiment. It is a top view which shows the modification of 1st Embodiment. It is a top view seen from one side in the z-axis direction of the current detection apparatus which concerns on 2nd Embodiment. It is a top view for showing the y-axis direction region in 2nd Embodiment. It is a top view seen from one side in the z-axis direction of the current detection apparatus which concerns on 3rd Embodiment. It is a schematic diagram of the measurement target system which concerns on 1st Example. It is a schematic diagram of the measurement target system which concerns on 2nd Example. It is a schematic diagram of the measurement target system which concerns on 3rd Example.

An embodiment of the present invention will be described below with reference to the drawings. In the drawings, the x-axis direction (first direction), the y-axis direction (second direction), and the z-axis direction (third direction) that are orthogonal to each other may be shown. In this case, the side pointed by the arrow is referred to as one side, and the opposite side is referred to as the other side.

<1. Magnetic field sensor configuration>
First, the configuration of the magnetic field sensor used in the current detection device according to the embodiment of the present invention will be described. FIG. 1 is a plan view of the IC package of the magnetic field sensor 1 as viewed from one side in the z-axis direction. FIG. 1 shows the positions of the first magnetic field detection unit 11 and the second magnetic field detection unit 12 provided inside the IC package. In FIG. 1, the black circle shown at the upper right end of the paper surface of the IC package is shown for convenience in order to specify the position of the corner of the IC package, and the black circle is also shown when the magnetic field sensor 1 is shown in other drawings. doing.

As shown in FIG. 1, the IC package of the magnetic field sensor 1 has a rectangular shape having a side extending in the x-axis direction and a side extending in the y-axis direction in a plan view (a plane including the x-axis direction and the y-axis direction). ..

The center position of the first magnetic field detection unit 11 in the x-axis direction is separated from the center position x0 in the x-axis direction of the IC package by a distance DX1 on the other side in the x-axis direction. The center position of the second magnetic field detection unit 12 in the x-axis direction is separated from the center position x0 in the x-axis direction by a distance DX2 on one side in the x-axis direction. Then, DX1 = DX2.

Further, the center position in the y-axis direction of the first magnetic field detection unit 11 and the center position in the y-axis direction of the second magnetic field detection unit 12 are both separated from the other end in the Y-axis direction of the IC package by a distance DY on one side in the y-axis direction. ing.

FIG. 2 is a block configuration diagram of the magnetic field sensor 1. The magnetic field sensor 1 includes a first magnetic field detection unit 11, a second magnetic field detection unit 12, a first sample / hold unit 141, a second sample / hold unit 142, a first amplifier unit 151, and a second amplifier unit. It has 152, a subtraction unit 16, an oscillation unit 17, and a pulse drive unit 18, and these components are integrated into one IC chip.

Each of the first magnetic field detection unit 11 and the second magnetic field detection unit 12 includes a shared magnetic impedance effect element (MI effect element) 13 and coils L1 and L2 wound around the common magnetic impedance effect element (MI effect element) 13, and each of the coils L1 and L2. The induced voltage generated between both ends of is output as sensor signals S11 and S12. The MI effect element 13 is configured as, for example, an amorphous wire.

The first sample / hold unit 141 and the second sample / hold unit 142 sample / hold the signal values (for example, peak values) of the sensor signals S11 and S12 in a predetermined phase in synchronization with the clock signal CLK, respectively. , Sample / hold signals S21 and S22 are generated.

Each of the first amplifier unit 151 and the second amplifier unit 152 generates amplification signals S31 and S32 by amplifying the sample / hold signals S21 and S22 with predetermined gains, respectively. The subtraction unit 16 subtracts the amplification signal S32 from the amplification signal S31 to generate the output signal S40.

The oscillation unit 17 generates a clock signal CLK having a predetermined frequency, and supplies the clock signal CLK to the sample / hold units 141 and 142 and the pulse drive unit 18. The pulse drive unit 18 generates a pulse wave-shaped drive current Ip in synchronization with the clock signal CLK, and supplies this to the MI effect element 13.

Here, the principle of the magnetic field detection method using the MI effect element 13 will be described. When the MI effect element 13 is not energized, the electron spins in the MI effect element 13 are directed in the circumferential direction. The circumferential direction is a direction around the axial direction of the MI effect element 13. Then, when an external magnetic field is applied to the MI effect element 13 that is not energized, the electron spin is tilted. Here, when the MI effect element 13 is energized, the electron spins are rotated by the magnetic field in the circumferential direction generated by the electric current, and are aligned in one direction in the circumferential direction. An induced voltage generated in the pickup coils (coils L11 and L12) is generated in the pickup coils (L11, L12) in proportion to the speed of the magnetic vector change in the axial direction of the MI effect element 13 generated during this rotation. After that, when the energization is released, the electron spin changes to a tilted state according to the external magnetic field, and an induced voltage proportional to the speed of the axial magnetic vector change of the MI effect element 13 at that time is generated in the pickup coil.

Therefore, as shown in FIG. 3, when the MI effect element 13 is energized by the drive current Ip from the state where it is not energized (rising of the pulse wave), the induced voltage VH corresponding to the external magnetic field is generated in the coils L11 and L12. Then, it is output as sensor signals S11 and S12. Further, when the energization by the drive current Ip is stopped from the state where the MI effect element 13 is energized (falling edge of the pulse wave), an induced voltage VL having a polarity opposite to the previous induced voltage is generated in the coils L11 and L12. , It is output as sensor signals S11 and S12. When the direction of the external magnetic field is reversed, the polarity of the generated induced voltage is also reversed.

That is, since the induced voltages VH and VL are generated by the pulse wave-shaped drive current Ip, the sample / hold units 141 and 142 are set to the peak value PH of the induced voltage VH when acquiring the peak values of the sensor signals S11 and S12. Any of the peak value PL of the induced voltage VL may be acquired.

<2. Comparative example>
Here, in order to help the understanding of the embodiment of the present invention, the current detection device according to the comparative example will be described before the embodiment is described.

FIG. 4 is a plan view of the current detection device 50 according to the comparative example as viewed from one side in the z-axis direction. Further, FIG. 5 is a cross-sectional view taken along the line AA when the magnetic field detection units 11 and 12 in FIG. 4 are cut along the AA cutting line crossing the x-axis direction.

As shown in FIG. 4, the current detection device 50 according to the comparative example includes a printed circuit board 20 that extends in a plane including the x-axis direction and the y-axis direction and has a thickness in the z-axis direction, and a magnetic field sensor 1. .. Wiring 20A is formed on the printed circuit board 20. The wiring 20A is formed of, for example, copper foil. The wiring 20A is a path through which the measurement target current I flows.

The wiring 20A includes an outward path portion 201 extending in the y-axis direction, a return path portion 202 extending in the y-axis direction, and a connecting portion 203. The outward path portion 201 and the return path portion 202 are arranged in the x-axis direction. The connecting portion 203 connects the one-sided end in the y-axis direction of the outward path portion 201 and the one-sided end in the y-axis direction of the returning path portion 202 in the x-axis direction. As a result, as shown in FIG. 4, the outward path portion 201, the return path portion 202, and the connecting portion 203 form a U-shape in a plan view. The connecting portion 203 may have a curved shape, and the outward path portion 201, the returning path portion 202, and the connecting portion 203 may form a U shape.

As shown in FIG. 4, the measurement target current I flows through the outward path portion 201 to one side in the y-axis direction, flows into the return path portion 202 via the connecting portion 203, and flows through the return path portion 202 to the other side in the y-axis direction. When the measurement target current I flows through the return path portion 202 to one side in the y-axis direction, it flows into the outward path portion 201 via the connecting portion 203, and flows through the outward path portion 201 to the other side in the y-axis direction. In this way, the outward path portion 201 and the return path portion 202 are provided so that the measurement target currents I flow in opposite directions to each other.

Further, as shown in FIG. 5, the magnetic field sensor 1 is arranged on the surface 20S on one side in the z-axis direction of the printed circuit board 20. As shown in FIG. 6, the first magnetic field detection unit 11 is arranged in the y-axis direction region R201 between the positions of both ends in the y-axis direction of the outward path unit 201 in a plan view. The second magnetic field detection unit 12 is arranged in the y-axis direction region R202 between the positions of both ends in the y-axis direction of the return path unit 202 in a plan view. In FIG. 6, both the y-axis direction regions R201 and R202 are regions sandwiched in the y-axis direction by two broken lines extending in the x-axis direction.

As shown in FIG. 5, the width of the outward path portion 201 in the x-axis direction and the width W2 of the return path portion 202 in the x-axis direction are the same in width W. Then, as shown in FIG. 4, in the plan view, the center position in the x-axis direction of the outward path portion 201 is separated from the center position x0 in the x-axis direction by a distance Dx11 to the other side in the x-axis direction, and the x-axis of the return path portion 202. The direction center position is separated from the x-axis direction center position x0 by a distance Dx12 on one side in the x-axis direction. Dx11 = Dx12.

As shown in FIG. 5, the measurement target current I flowing in the outward path portion 201 in the y-axis direction generates a magnetic field M1 clockwise when viewed in the y-axis direction on one side, and the return path portion 202 is generated in the y-axis direction on the other side. A magnetic field M2 is generated counterclockwise when viewed to one side in the y-axis direction due to the measurement target current I flowing to. As a result, the measurement target magnetic field (+ b) directed to one side in the x-axis direction is applied to the first magnetic field detection unit 11, and the measurement target magnetic field (-) toward the other side in the x-axis direction to the second magnetic field detection unit 12. b') is applied. Here, b and b'are almost the same. That is, the measurement target magnetic fields applied to the first magnetic field detection unit 11 and the second magnetic field detection unit 12, respectively, have substantially the same absolute value in the opposite direction.

At this time, as shown in FIG. 2, the measurement target magnetic field (+ b) is applied to the first magnetic field detection unit 11, and the measurement target magnetic field (−b ′) is applied to the second magnetic field detection unit 12. .. The sensor signal S21 generated in response to the measurement target magnetic field (+ b) has a positive value, the sensor signal S22 generated in response to the measurement target magnetic field (−b) has a negative value, and the sensor signals S21 and S22 are absolute. The values are approximately the same. Assuming that the gain values of the first amplifier unit 151 and the second amplifier unit 152 are equal at the gain value α, the sensor signals S21 and S22 are multiplied by α, respectively, and the amplification signals S31 and S32 are generated, and the subtraction unit 16 generates the amplification signals. S32 is subtracted from the amplified signal S31 to generate the output signal S40. As a result, the output signal S40 becomes a positive value obtained by further doubling the value obtained by multiplying the sensor signal S21 by α.

That is, as shown in FIGS. 4 and 5, when the measurement target current I flows through the outward path portion 201 in the y-axis direction, the output signal S40 becomes a positive value. When the measurement target current I flows through the return path portion 202 to one side in the y-axis direction, the measurement target magnetic field (−b) is applied to the first magnetic field detection unit 11 and the measurement target magnetic field (−b) is applied to the second magnetic field detection unit 12. Since the measurement target magnetic field (+ b') is applied, the sensor signal S21 has a negative value, S22 has a positive value, and the output signal S40 has a negative value.

In this way, according to the current detection device 50, the measurement target current I can be detected by generating the output signal S40 corresponding to the measurement target current I. In particular, since the first magnetic field detection unit 11 and the second magnetic field detection unit 12 detect the magnetic field using the MI effect element 13, the sensitivity of magnetic field detection becomes high, and the outward path unit 201 and the return path portion 202, which are conductors, are first. It is not necessary to bring the magnetic field detection unit 11 and the second magnetic field detection unit 12 close to each other, and the outward path unit 201 and the return path unit 202 can be provided on the printed circuit board 20 separate from the magnetic field sensor 1. Therefore, the loss can be suppressed as compared with the conventional retractable current sensor.

An environmental magnetic field that becomes a disturbance may be applied to the first magnetic field detection unit 11 and the second magnetic field detection unit 12 depending on the environment in which the current detection device 50 is placed. In this case, the environmental magnetic fields applied to the first magnetic field detection unit 11 and the second magnetic field detection unit 12 are in phase (+ a or −a) with each other. FIG. 2 shows a case where the in-phase (+ a) is applied as an example. In this case, the amplification signals S31 and S32 are canceled by the subtraction unit 16, and the output signal S40 becomes zero. That is, the output signal S40 in which the influence of the environmental magnetic field is canceled can be obtained.

Further, by adjusting each parameter of the printed circuit board 20 shown in FIG. 5, the magnetic fields applied to the first magnetic field detection unit 11 and the second magnetic field detection unit 12 can be adjusted to adjust the current detection sensitivity. Here, the current detection sensitivity is a value indicating a change in the output signal S40 with respect to a change in 1A of the current to be measured I.

For example, FIG. 7A shows an example of the correlation between the width W of the outward path portion 201 and the return path portion 202 shown in FIG. 5 and the current detection sensitivity. As shown in FIG. 7A, the wider the width W, the lower the current detection sensitivity. Further, FIG. 7B is an example of the correlation between the distance Dz in the z-axis direction between the magnetic field sensor 1 (that is, the surface 20S on one side in the z-axis direction of the printed circuit board 20) and the wiring 20A shown in FIG. 5 and the current detection sensitivity. Shown in. As shown in FIG. 7B, the longer the distance Dz, the lower the current detection sensitivity. Further, FIG. 7C shows an example of the correlation between the distance S in the x-axis direction between the outward path portion 201 and the return path portion 202 shown in FIG. 5 and the current detection sensitivity. As shown in FIG. 7C, the longer the distance S, the lower the current detection sensitivity.

In this way, in the current detection device 50, since the magnetic field sensor 1 can adjust the current detection sensitivity by adjusting the parameters of the printed substrate 20 in common, the product is manufactured for each current detection sensitivity like the conventional retractable current sensor. There is no need to prepare. Further, in the retractable current sensor, the current detection sensitivity is different for each product, so that the current detection sensitivity cannot be finely adjusted. However, in the current detection device 50, the current detection sensitivity can be finely adjusted.

However, in the current detection device 50, since the wiring 20A on the printed circuit board 20 has a single layer, when the measurement target current I is to be increased, the width of the wiring 20A is widened or the thickness of the wiring 20A is increased in order to suppress heat generation. Need to be thickened. However, if the width of the wiring 20A is widened, it hinders the compactification of the printed circuit board 20, and if the thickness of the wiring 20A is increased, the printed circuit board 20 may become expensive. In addition, the magnetic field sensor 1 may be saturated with respect to the increased measurement target current I. As described above, the current detection device 50 has room for improvement when the current to be measured increases.

<3. First Embodiment>
Next, the current detection device according to the first embodiment of the present invention will be described. FIG. 8 is a plan view of the current detection device 5 according to the first embodiment as viewed from one side in the z-axis direction. FIG. 9 is a cross-sectional view taken along the line AA in FIG. FIG. 10 is a cross-sectional view taken along the line BB in FIG.

The current detection device 5 includes a magnetic field sensor 1 and a printed circuit board 2 that extends in a plane including the x-axis direction and the y-axis direction and has a thickness in the z-axis direction. The magnetic field sensor 1 is arranged on the surface 2S on one side of the printed circuit board 2 in the z-axis direction. The printed circuit board 2 includes a first wiring 21 which is a first layer and a second wiring 22 which is a second layer. The second wiring 22 is arranged on the other side in the z-axis direction from the first wiring 21. The first wiring 21 and the second wiring 22 are formed of, for example, copper foil.

As shown in FIG. 8, the first wiring 21 has the same shape as the wiring 20A (FIG. 4) according to the comparative example described above in a plan view. The first wiring 21 includes an outward route portion 211, a return route portion 212, and a connecting portion 213. The first wiring 21 has a constant width W21 along the current path.

A through hole 231 extending in the z-axis direction is formed in the vicinity of the current inflow portion 21A of the first wiring 21. A through hole is a through hole in which a conductor is filled inside or a conductor is formed on an inner wall surface. A through hole 232 extending in the z-axis direction is formed in the vicinity of the current outflow portion 21B of the first wiring 21. The first wiring 21 and the second wiring 22 are connected by through holes 231 and 232.

In the second wiring 22, the connection point with the through hole 231 is the start point of the wiring, and the connection point with the through hole 232 is the end point of the wiring. As shown in FIG. 8, the second wiring 22 has the same shape as a part of the first wiring 21 in a plan view, and the entire second wiring 22 overlaps with the first wiring 21 in a plan view. The second wiring 22 has a constant width W22 along the current path. W21 = W22.

The second wiring 22 includes an outward path portion 221 that overlaps the outward path portion 211 in a plan view, a return path portion 222 that overlaps the return path portion 212 in a plan view, and a connecting portion 223 that overlaps the connecting portion 213 in a plan view.

The measurement target current I that has flowed into the current inflow unit 21A is distributed to a first current I1 that flows through the first wiring 21 and a second current I2 that flows into the second wiring 22 through the through hole 231. The first current I1 flows in this order through the outward path portion 211, the connecting portion 213, and the return path portion 212. The second current I2 flows in this order through the outward path portion 221 and the connecting portion 223, and the return path portion 222. Then, the two-current I2 flows into the current outflow portion 21B through the through hole 232 and is combined with the first current I1 to become the measurement target current I. It is also possible that the measurement target current I flows into the current outflow section 21B and the measurement target current I flows out from the current inflow section 21A. In that case, the first current I1 and the second current I2 flow in the opposite directions to those described above.

As a result, as shown in FIG. 9, in the outward path portion 211, the first current I1 flowing in one side in the y-axis direction generates a magnetic field M11 clockwise in the direction of one side in the y-axis. In the outward path portion 221, a right-handed magnetic field M12 is generated when viewed to one side of the y-axis by the second current I2 flowing to one side in the y-axis direction. In the return path portion 212, a counterclockwise magnetic field M21 is generated when viewed toward one side of the y-axis by the first current I1 flowing to the other side in the y-axis direction. In the return path portion 222, a counterclockwise magnetic field M22 is generated when viewed to one side of the y-axis due to the second current I2 flowing to the other side in the y-axis direction.

Here, as shown in FIG. 11, the first magnetic field detection unit 11 is arranged in the y-axis direction region R211 between the positions of both ends in the y-axis direction of the outward path unit 211 in a plan view, and is arranged in the y-axis direction region R211 in a plan view. It is arranged in the y-axis direction region R221 between the positions of both ends in the y-axis direction of 221. The second magnetic field detection unit 12 is arranged in the y-axis direction region R212 between the positions of both ends of the return path portion 212 in the y-axis direction in a plan view, and y in the plan view between the positions of both ends of the return path portion 222 in the y-axis direction. It is arranged in the axial region R222. In FIG. 11, the y-axis direction regions R211, R221, R212, and R222 are all regions sandwiched in the y-axis direction by two broken lines extending in the x-axis direction.

As a result, a magnetic field (+ b1) due to the magnetic field M11 and a magnetic field (+ b2) due to the magnetic field M12 are applied to the first magnetic field detection unit 11, and a magnetic field (-b1') due to the magnetic field M21 is applied to the second magnetic field detection unit 112. ) And the magnetic field (−b2 ′) generated by the magnetic field M22. b1 and b1', b2 and b2' are almost equal, respectively.

Therefore, according to the configuration shown in FIG. 2, the sample / hold signal S21 corresponding to the magnetic field (+ b1, + b2) applied to the first magnetic field detection unit 11 is generated, and the magnetic field applied to the second magnetic field detection unit 12 is generated. The sample / hold signal S22 corresponding to (-b1', -b2') is generated. As a result, the output signal S40 as the detection signal of the measurement target current I is generated.

As described above, in the present embodiment, the measurement target current I can be detected by causing the magnetic field sensor 1 to detect the magnetic fields generated by each of the first current I1 and the second current I2 to which the measurement target current I is distributed.

In particular, in the present embodiment, since the wiring on the printed circuit board 2 has a two-layer configuration, even if the measurement target current I is increased, the printed circuit board 2 can be made more compact than the width of the same layer wiring is widened, or the same layer wiring can be obtained. The printed circuit board 2 can be made cheaper than the thickness of the printed circuit board 2.

Further, in the configuration examples shown in FIGS. 8 and 9, the width W21 of the first wiring 21 and the width W22 of the second wiring 22 are the same, and the thickness t21 of the first wiring 21 and the thickness t22 of the second wiring 22 are the same. There is. Further, the path length L21 (FIG. 11) from the connection point with the through hole 231 in the first wiring 21 to the connection point with the through hole 232 is the through hole 232 from the connection point with the through hole 231 in the second wiring 22. It is the same as the path length L22 (FIG. 11) to the connection point of.

As a result, when the first wiring 21 and the second wiring 22 are formed of the same conductive material, the resistance value (hereinafter referred to as the first resistance value) between the connection points of the first wiring 21 with the through holes 231 and 232 becomes. , The resistance value between the connection points of the second wiring 22 with the through holes 231 and 232 (hereinafter referred to as the second resistance value) is substantially the same. Therefore, the measurement target current I is equally distributed to the first current I1 and the second current I2.

However, the present invention is not limited to this, and the widths W21 and W22 may be different, the thicknesses t21 and t22 may be different, and the path lengths L21 and L22 may be different. FIG. 12 is a plan view showing a modified example in which the path length L22 of the second wiring 22 is made longer than the path length L21 of the first wiring 21. Alternatively, the first wiring 21 and the second wiring 22 may be formed of different conductive materials.

By doing so, the distribution ratio between the first current I1 and the second current I2 can be adjusted by adjusting the first resistance value and the second resistance value.

Further, the current detection sensitivity can be adjusted by making the widths W21 and W22 different as described above. Further, the x-axis direction distance S1 between the outward path portion 211 and the return path portion 212 in the first wiring 21 shown in FIG. 9 and the x-axis direction distance S2 between the outward path portion 221 and the return path portion 222 in the second wiring 22. The current detection sensitivity can also be adjusted by making them different. Further, between the z-axis direction distance Dz1 between the magnetic field sensor 1 (that is, the surface 2S on one side in the z-axis direction of the printed substrate 2) and the first wiring 21 shown in FIG. 9, and between the magnetic field sensor 1 and the second wiring 22. The current detection sensitivity can be adjusted by adjusting the z-axis direction distance Dz2.

<4. Second Embodiment>
Next, a second embodiment of the present invention will be described. FIG. 13 is a plan view of the current detection device 5 according to the second embodiment as viewed from one side in the z-axis direction.

The difference from the above-mentioned first embodiment (FIG. 8) of the current detection device 5 shown in FIG. 13 is the configuration of the outward path portion 221, the return path portion 222, and the connecting portion 223 included in the second wiring 22. Specifically, in a plan view, the outward path portion 211 is formed so as to extend from the upstream side of the current path to one side in the y-axis direction, whereas the outward path portion 221 is formed from the upstream side of the current path to the other side in the y-axis direction. It is extended and formed. Further, in a plan view, the return path portion 212 is formed so as to extend from the downstream side of the current path to one side in the y-axis direction, whereas the return path portion 222 is formed so as to extend from the downstream side of the current path to the other side in the y-axis direction. Will be done. The connecting portion 223 connects the other end of the outward path portion 221 in the y-axis direction and the other end of the return path portion 222 in the y-axis direction.

As a result, as shown in FIG. 14, the first magnetic field detection unit 11 is arranged in the y-axis direction region R211 between the positions of both ends in the y-axis direction of the outward path unit 211 in a plan view. The second magnetic field detection unit 12 is arranged in the y-axis direction region R212 between the positions of both ends in the y-axis direction of the return path unit 212 in a plan view. In FIG. 14, both the y-axis direction regions R211 and R212 are regions sandwiched in the y-axis direction by two broken lines extending in the x-axis direction. The second wiring 22 does not overlap with the y-axis direction regions R211 and R212 in a plan view.

In this way, the magnetic field generated by the first current I1 in the outward path section 211 and the return path section 212 is detected by the first magnetic field detection section 11 and the second magnetic field detection section 12, and the outward path section 221 and the return path section 222 are the second. The magnetic field generated by the two currents I2 can be prevented from being detected by the first magnetic field detection unit 11 and the second magnetic field detection unit 12. As a result, even if the measurement target current I is increased, only the first current I1 that is smaller than the measurement target current I is detected by the magnetic field sensor 1, so that saturation of the magnetic field sensor 1 can be avoided.

The measurement target current I can be detected based on the distribution ratio of the first current I1 and the first current I1 and the second current I2 detected by the magnetic field sensor 1. It is possible to adjust the distribution ratio between the first current I1 and the second current I2 by adjusting the first resistance value and the second resistance value by adjusting parameters such as the widths of the first wiring 21 and the second wiring 22. , The same as the first embodiment.

<5. Third Embodiment>
The third embodiment of the present invention is a modification of the second embodiment. FIG. 15 is a plan view of the current detection device 5 according to the third embodiment as viewed from one side in the z-axis direction.

In the present embodiment, the wiring formed on the printed circuit board 2 is the wiring 20B of the same layer, and the single-layer wiring 20B includes the first wiring 2100 and the second wiring 2200 that branch. The first wiring 2100 includes an outward path portion 211 and a return path portion 212. The second wiring 2200 includes an outward path portion 221 and a return path portion 222. The first current I1 flows through the first wiring 2100, and the second current I2 flows through the second wiring 2200.

As shown in FIG. 15, the first magnetic field detection unit 11 is arranged in the y-axis direction region R211 between the positions of both ends in the y-axis direction of the outward path unit 211 in a plan view. The second magnetic field detection unit 12 is arranged in the y-axis direction region R212 between the positions of both ends in the y-axis direction of the return path unit 212 in a plan view. In FIG. 15, both the y-axis direction regions R211 and R212 are regions sandwiched in the y-axis direction by two broken lines extending in the x-axis direction. The second wiring 2200 does not overlap with the y-axis direction regions R211 and R212 in a plan view.

Even with such a third embodiment, the same effects as those of the second embodiment can be enjoyed.

<6. Measurement target system>
Next, various examples of the measurement target system including the above-mentioned current detection device 5 will be described.

FIG. 16 is a schematic view of the measurement target system 1001 according to the first embodiment. The measurement target system 1001 shown in FIG. 16 includes the current detection device 5 according to the first embodiment. A current detection device 5 is provided on the path between the positive end of the power supply E and the load Z. The current detection device 5 detects the measurement target current I flowing from the positive end of the power source E to the load Z.

FIG. 17 is a schematic view of the measurement target system 1002 according to the second embodiment. The measurement target system 1002 is a modification of the measurement target system 1001 (FIG. 16). Specifically, the outward route portion 221 and the return route portion 222 are directly connected by the connecting portion 223, but the outward route portion 211 and the return route portion 212 are directly connected by the connecting portion 213 as shown in FIG. Instead of connecting, they are connected by the connecting portion 214 via the load Z2. As a result, the first current I1 flows from the outward path portion 211 to the return path portion 212 via the load Z2.

As a modification of the second embodiment, the outward path portion 221 and the return path portion 222 may be connected by a connecting portion via a load.

FIG. 18 is a schematic view of the measurement target system 1003 according to the third embodiment. The measurement target system 1003 shown in FIG. 18 includes a modification of the current detection device 5 according to the second embodiment. A current detection device 5 is provided on the path between the positive end of the power supply E and the load Z1. The outbound route portion 221 and the inbound route portion 222 are directly connected by a connecting portion 223, but the outbound route portion 211 and the inbound route portion 212 are connected by a connecting portion 214 via a load Z2. As a result, the first current I1 flows from the outward path portion 211 to the return path portion 212 via the load Z2.

As a modification of the third embodiment, the outward path portion 221 and the return path portion 222 may be connected by a connecting portion via a load.

<7. Others>
Although the embodiments of the present invention have been described above, the embodiments can be changed in various ways within the scope of the gist of the present invention.

For example, in the printed circuit board 2, wiring of the third layer or later may be added. In this case, the wiring of the third and subsequent layers may be the same as the second wiring 22 of the first embodiment, or may be the same as the second wiring 22 of the second embodiment.

The present invention can be used, for example, in a current detection device for industrial equipment.

1 Magnetic field sensor 11 1st magnetic field detection unit 12 2nd magnetic field detection unit 13 MI (magnetic impedance) effect element 141 1st sample / hold unit 142 2nd sample / hold unit 151 1st amplifier unit 152 2nd amplifier unit 16 Subtraction unit 17 Oscillating part 18 Pulse drive part 2 Printed board 21 1st wiring 21A Current inflow part 21B Current outflow part 211 Outward path part 212 Return path section 213, 214 Connecting section 22 2nd wiring 221 Outward path section 222 Return path section 223 Connecting section 231, 232 Through Hall 2100 1st wiring 2200 2nd wiring 5 Current detector 1001-1003 Measurement target system E Power supply Z, Z1, Z2 Load

Claims (9)

Assuming that the first direction, the second direction, and the third direction are orthogonal to each other,
A substrate that spreads in a plane including the first direction and the second direction and has a thickness in the third direction.
A magnetic field sensor arranged on the surface of the substrate on one side in the third direction,
With
The magnetic field sensor has a first magnetic field detection unit and a second magnetic field detection unit.
The substrate has a first wiring and a second wiring arranged on the other side of the first wiring in the third direction.
One end of the first wiring and one end of the second wiring are electrically connected to each other.
The other end of the first wiring and the other end of the second wiring are electrically connected.
The first wiring includes a first outward path portion extending in the second direction and a first return path portion extending in the second direction.
The first return path portion is arranged on one side in the first direction with respect to the first outward path portion, and is electrically connected to the first outward path portion.
The second wiring includes a second outward path portion extending in the second direction and a second return path portion extending in the second direction.
The second return path portion is arranged on one side of the first direction with respect to the second outward path portion, and is electrically connected to the second outward path portion.
The first magnetic field detection unit is arranged in a first second direction region between the positions of both ends of the second direction of the first outward path portion in a plan view of a plane including the first direction and the second direction. Moreover, in the plan view, it is arranged in the second second direction region between the positions of both ends of the second direction of the second outward path portion.
The second magnetic field detection unit is arranged in a third second direction region between the positions of both ends of the first return path portion in the second direction in the plan view, and the second return path portion is arranged in the plan view. Is arranged in the fourth second direction region between the positions of both ends in the second direction of the above.
Current detector. The width of the first outward path portion and the width of the first return path portion are the same first width.
The width of the second outward path portion and the width of the second return path portion are the same second width.
The current detection device according to claim 1, wherein the first width and the second width are different. Claims that the first-direction distance between the first outward path portion and the first return path portion and the first-direction distance between the second outward path portion and the second return path portion are different. The current detection device according to claim 1 or 2. 1. Claim 1 in which at least one of the first outward path portion and the first return path portion and between the second outward path portion and the second return path portion is connected by a connection portion via a load. The current detection device according to any one of claims 3. Assuming that the first direction, the second direction, and the third direction are orthogonal to each other,
A substrate that spreads in a plane including the first direction and the second direction and has a thickness in the third direction.
A magnetic field sensor arranged on the surface of the substrate on one side in the third direction,
With
The magnetic field sensor has a first magnetic field detection unit and a second magnetic field detection unit.
The substrate has a first wiring and a second wiring.
One end of the first wiring and one end of the second wiring are electrically connected to each other.
The other end of the first wiring and the other end of the second wiring are electrically connected.
The first wiring includes a first outward path portion extending in the second direction and a first return path portion extending in the second direction.
The first return path portion is arranged on one side in the first direction with respect to the first outward path portion, and is electrically connected to the first outward path portion.
The first magnetic field detection unit is arranged in a first second direction region between the positions of both ends of the second direction of the first outbound route unit in a plan view of a plane including the first direction and the second direction.
The second magnetic field detection unit is arranged in the second second direction region between the positions of both ends of the second direction of the first return path unit in the plan view.
The second wiring does not overlap with the first second direction region and the second second direction region in the plan view.
Current detector. The current detecting device according to claim 5, wherein the first outward path portion and the first return path portion are connected by a connecting portion via a load. The current detection device according to claim 5 or 6, wherein the first wiring and the second wiring are included in wiring of the same layer. The current detection device according to any one of claims 1 to 7, wherein at least one of the width, thickness, path length, and material of the first wiring and the second wiring is different. The current detection device according to any one of claims 1 to 8, wherein the first magnetic field detection unit and the second magnetic field detection unit detect a magnetic field using an MI (magnetic impedance) effect element.

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