JP2021085712A - Current detector - Google Patents

Abstract

To provide a current detector which is of a low loss type, and with which it is possible to improve the S/N ratio of a detection signal even when the amount of current to be detected is small.SOLUTION: A substrate 2 includes first wiring 2A of the same layer, the first wiring 2A including a plurality of outward paths 21A-21C extending in a second direction (y axis direction) and arrayed in a first direction (x axis direction) and a plurality of homeward paths 22A-22C extending in the second direction and arrayed in the first direction, the plurality of homeward paths 22A-22C being arranged on one side in the first direction relative to the plurality of outward paths 21A-21C. A first magnetic field detection part 11 is, in a plan view of a plane that includes the first and second directions, arranged in a first second-direction area which the plurality of outward paths 21A-21C overlap as seen in the first direction, and a second magnetic field detection part 12 is, in the plan view, arranged in a second second-direction area which the plurality of homeward paths 22A-22C overlap as seen in the first direction.SELECTED DRAWING: Figure 8

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 improving the S / N ratio of the detection signal even when the amount of current to be detected is small.

The current detection device according to 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 the first wiring of the same layer and has.
The first wiring includes a plurality of outward paths extending in the second direction and arranged in the first direction, and a plurality of return paths extending in the second direction and arranged in the first direction. ,
The plurality of return paths are arranged on one side of the first direction with respect to the plurality of outward paths.
The first magnetic field detection unit is arranged in a first second direction region in which the plurality of outward path portions overlap when viewed in the first direction in a plan view of a plane including the first direction and the second direction.
The second magnetic field detection unit is configured to be arranged in a second second direction region in which the plurality of return path portions overlap when viewed in the first direction in the plan view (first configuration).

Further, in the first configuration, the plurality of outward paths are defined as m first outward paths (m = 1 to n), and the plurality of return paths are designated as m third return paths (m = 1 to n) (n: 3 or more). Integer)
The first outbound route portion to the nth outbound route portion are arranged in order on one side in the first direction.
The first return path section to the nth return path section are arranged in order on the other side in the first direction.
With m being 2 or more, the one-sided end in the second direction of the m-outward route portion and the one-sided end in the second direction of the m-return route portion are connected in the first direction.
When m is 2 or more, the other end in the second direction of the m return path portion and the other end in the second direction of the (m + 1) outward path portion may be connected in the first direction (m). Second configuration).

Further, in the second configuration, the substrate has an output wiring that crosses the first to first (n-1) return paths in the second direction and the second direction of the nth return path in the plan view. It may have a through hole extending in the third direction by electrically connecting the side end and the output wiring (third configuration).

Further, in any of the first to third configurations, the substrate is arranged on the other side of the third direction from the first wiring and further has a second wiring of the same layer.
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 second wiring includes a plurality of lower outward paths extending in the second direction and arranged in the first direction, and a plurality of lower return paths extending in the second direction and arranged in the first direction. And, including
The plurality of lower return paths are arranged on one side of the first direction with respect to the plurality of lower outward paths.
The first magnetic field detection unit is arranged in a third second direction region in which the plurality of lower outward path portions overlap when viewed in the first direction in the plan view.
The second magnetic field detection unit may be arranged in a fourth second direction region in which the plurality of lower return paths overlap in the first direction in the plan view (fourth configuration). ..

Further, in the fourth configuration, the plurality of lower outward paths are defined as m lower outward paths (m = 1 to 1), and the plurality of lower return sections are designated as m lower return sections (m = 1). ~ L) (l: an integer of 3 or more)
The first lower outbound route portion to the l lower outbound route portion are arranged in order on one side in the first direction.
The first lower return section to the first lower return section are arranged in order on the other side in the first direction.
With m being 2 or more, the one-sided end in the second direction of the lower m lower outbound route and the one-sided end in the second direction of the lower m lower inbound route are connected in the first direction.
When m is 2 or more, the other end in the second direction of the lower return path portion of m and the other end in the second direction of the (m + 1) lower outward path portion are connected in the first direction. (Fifth configuration).

Further, in the fifth configuration, the substrate has an output wiring that crosses the first to first (n-1) lower return paths in the second direction in the plan view, and the nth lower return path section. It may have a through hole extending in the third direction by electrically connecting the other end in the second direction and the output wiring (sixth configuration).

Further, in any of the fourth to sixth configurations, the width of the outward path portion and the width of the return path portion are the same first width, and the width of the lower outward path portion and the width of the lower return path portion. Is the same second width, and the first width and the second width may be different (seventh configuration).

Further, in any of the fourth to seventh configurations, the first path portion between the outward path portion arranged at one side end in the first direction and the return path portion arranged at the other side end in the first direction. The one-way distance and the first-way distance between the lower outward path portion arranged at the one-side end in the first direction and the lower return path portion arranged at the other end in the first direction are: It may be different (eighth configuration).

Further, in any of the fourth to eighth 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). 9 configuration).

Further, in any of the fourth to ninth configurations, the lower outward path portion and the lower return path portion may be connected by a connecting portion via a load (tenth configuration).

Further, in any of the first to tenth configurations, the outward path portion and the return path portion may be connected by a connecting portion via a load (11th configuration).

Further, in any of the first to eleventh 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 (first). 12 configurations).

According to the current detection device of the present invention, the S / N ratio of the detection signal can be improved even when the loss is low and the amount of current to be detected is small.

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. It is a top view for showing the y-axis direction region in 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. 11 is a cross-sectional view taken along the line AA in FIG. FIG. 11 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 2nd 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.

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 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, when the current amount of the detection target current I is small, the generated magnetic fields M1 and M2 are small, and the magnetic fields applied to the first magnetic field detection unit 11 and the second magnetic field detection unit 12 are small. , There is a risk that the S / N ratio, which is the ratio of the output signal S40, which is the detection signal, to the noise, becomes small. As described above, the current detection device 50 has room for improvement when the amount of the current to be detected I is small.

<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.

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 wiring 2A having the same layer, a through hole 24, and an output wiring 25 having a layer different from the wiring 2A. The wiring 2A and the output wiring 25 are formed of, for example, copper foil.

The wiring 2A includes an outward route portion 21A to 21C, a return route portion 22A to 22C, and a connection portion 23A to 23E. The outward path portions 21A to 21C are arranged in order toward one side in the x-axis direction. The return paths 22A to 22C are arranged in order toward the other side in the x-axis direction. The connecting portions 23A to 23C are sequentially arranged toward the other side in the y-axis direction. The connecting portions 23D and 23E are arranged in order toward one side in the y-axis direction.

The one-sided end in the y-axis direction of the outward path portion 21A and the one-side end in the y-axis direction of the return path portion 22A are connected in the x-axis direction by the connecting portion 23A. The other end in the y-axis direction of the return path portion 22A and the other end in the y-axis direction of the outward path portion 21B are connected in the x-axis direction by the connecting portion 23D. The one-sided end in the y-axis direction of the outward path portion 21B and the one-side end in the y-axis direction of the return path portion 22B are connected in the x-axis direction by the connecting portion 23B. The other end in the y-axis direction of the return path portion 22B and the other end in the y-axis direction of the outward path portion 21C are connected in the x-axis direction by the connecting portion 23E. The one-sided end in the y-axis direction of the outward path portion 21C and the one-side end in the y-axis direction of the return path portion 22C are connected in the x-axis direction by the connecting portion 23C.

As a result, the outward path portions 21A to 21C, the return path portions 22A to 22C, and the connecting portions 23A to 23E form a spiral wiring that is wound clockwise from one side in the z-axis direction from the outside to the inside. If the wiring is spiral, it is possible to avoid overlapping the wiring from the start point to the end point of the wiring in a plan view.

The other end in the y-axis direction of the return path portion 22C is electrically connected to the other end in the x-axis direction of the output wiring 25 by the through hole 24. A through hole is a through hole in which a conductor is filled inside or a conductor is formed on an inner wall surface. The output wiring 25 is arranged on one side in the z-axis direction or the other side in the z-axis direction with respect to the wiring 2A. The through hole 24 extends in the z-axis direction. The output wiring 25 extends in the x-axis direction and crosses the return paths 22B and 22A in the x-axis direction when viewed from one side in the z-axis direction.

As shown in FIG. 8, when the measurement target current I flows into the other end of the outward path portion 21A in the y-axis direction, the measurement target current I flows through the outward path portions 21A to 21C toward one side in the y-axis direction. A current I to be measured flows through the return paths 22A to 22C toward the other side in the y-axis direction. Then, the measurement target current I flows out from the other end of the return path portion 22C in the y-axis direction to the output wiring 25 through the through hole 24.

As a result, as shown in FIG. 9, magnetic fields M1A, M1B, and M1C that are clockwise when viewed to one side in the y-axis direction are generated in the outward path portions 21A to 21C, and the y-axis direction is generated in the return path portions 22A to 22C. A counterclockwise magnetic field M2A, M2B, M2C is generated when viewed to one side.

Here, as shown in FIG. 10, the first magnetic field detection unit 11 is arranged in the y-axis direction region R201 where the outward paths 21A to 21C overlap in the x-axis direction in a plan view, and the second magnetic field detection unit 12 Is arranged in the y-axis direction region R202 where the return paths 22A to 22C overlap when viewed in the x-axis direction in a plan view. In FIG. 10, the y-axis direction region R201 is a region sandwiched in the y-axis direction by the broken lines Ln1 and Ln2 extending in the x-axis direction, and the y-axis direction region R202 is a region sandwiched in the y-axis direction by the broken lines Ln1 and Ln3 extending in the x-axis direction. It is an area sandwiched in the direction.

As a result, as shown in FIG. 9, a 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 other side in the x-axis direction is applied to the second magnetic field detection unit 12. The magnetic field to be measured (-B') toward 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.

As described above, according to the present embodiment, by forming the plurality of outward path portions (21A to 21C) and the plurality of return path portions (22A to 22C), even when the current amount of the measurement target current I is small, the first It is possible to increase the magnetic field applied to the magnetic field detection unit 11 and the second magnetic field detection unit 12. Therefore, the S / N ratio of the output signal S40 (FIG. 2), which is a detection signal, can be increased.

When the measurement target current I flows into the output wiring 25, the direction of the measurement target current I flowing through the outward path portions 21A to 21C and the return path portions 22A to 22C is opposite to that described above.

Further, in the present embodiment, the number of each of the outward path portion and the return path portion is not limited to three, and may be two or four or more.

<4. Second Embodiment>
Next, the current detection device according to the second embodiment of the present invention will be described. FIG. 11 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. FIG. 12 is a cross-sectional view taken along the line AA in FIG. 11 when cut along the AA cutting line. FIG. 13 is a sectional view taken along line BB in FIG. 11 when cut along the BB cutting line.

In the present embodiment, the printed circuit board 2 includes the first wiring 2A which is the same layer and the second wiring 2B which is the same layer. The first wiring 2B is arranged on the other side in the z-axis direction with respect to the first wiring 2A. That is, the first wiring 2A and the second wiring 2B are different layers.

The first wiring 2A includes an outward route portion 21A1 to 21C1, a return route portion 22A1 to 22C1, and a connecting portion 23A1 to 23E1. The wiring configuration of the first wiring 2A by each of the above parts is the same as that of the wiring 2A (FIG. 8) according to the first embodiment described above. That is, the first wiring 2A is formed with a spiral wiring that is wound clockwise from the outside to the inside when viewed from one side in the z-axis direction.

A through hole 26 extending in the z-axis direction is formed in the vicinity of the current inflow portion 2A1 of the first wiring 2A. The first wiring 2A and the second wiring 2B are connected by a through hole 26.

In the second wiring 2B, the connection point with the through hole 26 is the start point of the wiring. The second wiring 2B includes an outward path portion (lower outward path portion) 21A2 to 21C2, a return path portion (lower return path portion) 22A2 to 22C2, and a connecting portion (lower connecting portion) 23A2 to 23E2. The wiring configuration of the second wiring 2B by each of the above parts is the same as that of the wiring 2A (FIG. 8) according to the first embodiment described above. That is, the second wiring 2B is formed with a spiral wiring that is wound clockwise from the outside to the inside when viewed from one side in the z-axis direction. In FIG. 11, the spiral shapes of the first wiring 2A and the second wiring 2B are shown overlapping.

The other end in the y-axis direction of the return path portion 22C1, the other end in the y-axis direction of the return path portion 22C2, and the other end in the x-axis direction of the output wiring 25 are electrically connected by a through hole 24 extending in the z-axis direction. Will be done. The output wiring 25 is arranged on one side in the z-axis direction with respect to the first wiring 2A, or is arranged on the other side in the z-axis direction with respect to the second wiring 2B, or is arranged with the first wiring 2A in the z-axis direction. It is arranged between the second wiring 2B and the second wiring 2B. The output wiring 25 extends in the x-axis direction and crosses the return paths 22B1, 22, B2 and the return paths 22A 1, 22, A2 in the x-axis direction when viewed from one side in the z-axis direction.

As shown in FIGS. 11 and 13, when the measurement target current I flows into the current inflow section 2A1, the inflowing measurement target current I passes through the first current I1 flowing through the first wiring 2A and the through hole 26. It is distributed to the second current I2 flowing into the second wiring 2B.

The first current I1 flows through the outward paths 21A1 to 21C1 toward one side in the y-axis direction, and the first current I1 flows through the return paths 22A1 to 22C1 toward the other side in the y-axis direction. A second current I2 flows in the outward path portions 21A2 to 21C2 toward one side in the y-axis direction, and a second current I2 flows in the return path portions 22A2 to 22C2 toward the other side in the y-axis direction. Then, the first current I1 and the second current I2 are combined to form the measurement target current I, and the measurement target current I flows out to the output wiring 25.

As a result, as shown in FIG. 12, magnetic fields M11A, M11B, and M11C that are clockwise when viewed to one side in the y-axis direction are generated in the outward path portions 21A1 to 21C1, and the y-axis direction is generated in the return path portions 22A1 to 22C1. A counterclockwise magnetic field M21A, M21B, M21C is generated when viewed to one side. Further, magnetic fields M12A, M12B, and M12C that rotate clockwise when viewed to one side in the y-axis direction are generated in the outward path portions 21A2 to 21C2, and magnetic fields M12A, M12B, and M12C that rotate clockwise when viewed to one side in the y-axis direction. Magnetic fields M22A, M22B, M22C are generated.

Here, as shown in FIG. 14, the first magnetic field detection unit 11 is arranged in the y-axis direction region R2011 where the outward path portions 21A1 to 21C1 overlap in the x-axis direction in a plan view, and is arranged in the x-axis direction. It is arranged in the y-axis direction region R2012 where the outward path portions 21A2 to 21C2 overlap with each other. The second magnetic field detection unit 12 is arranged in the y-axis direction region R2021 where the return paths 22A1 to 22C1 overlap when viewed in the x-axis direction, and the return path portions 22A2 to 22C2 overlap when viewed in the x-axis direction. It is arranged in the axial region R2022. In FIG. 14, y-axis direction regions R2011 and R2012 are regions sandwiched in the y-axis direction by broken lines Ln11 and Ln12 extending in the x-axis direction, and y-axis direction regions R2021 and R2022 are broken lines Ln11 extending in the x-axis direction. This is a region sandwiched by Ln13 in the y-axis direction.

As a result, as shown in FIG. 12, the magnetic fields M11A to M11C apply the measurement target magnetic field (+ B1) toward the first magnetic field detection unit 11 on one side in the x-axis direction, and the magnetic fields M21A to M21C detect the second magnetic field. A magnetic field to be measured (−B1 ′) directed to the other side in the x-axis direction is applied to the unit 12. Here, B1 and B1'are almost the same. Further, the magnetic fields M12A to M12C apply a measurement target magnetic field (+ B2) toward one side in the x-axis direction with respect to the first magnetic field detection unit 11, and the magnetic fields M22A to M22C apply the measurement target magnetic field (+ B2) to the second magnetic field detection unit 12 in the x-axis direction. A magnetic field to be measured (-B2') toward the other side is applied. Here, B2 and B2'are almost the same.

As described above, according to the present embodiment, a plurality of outward path portions (21A1 to 21C1) and a plurality of return path portions (22A1 to 22C1) are formed in the first wiring 2A, and a plurality of outward path portions (21A2) are formed in the second wiring 2B. ~ 21C2) and a plurality of return paths (22A2 to 22C2) are formed. As a result, even when the amount of the current I to be measured is small, it is possible to increase the magnetic fields applied to the first magnetic field detection unit 11 and the second magnetic field detection unit 12. Therefore, the S / N ratio of the output signal S40 (FIG. 2), which is a detection signal, can be increased.

In particular, in the present embodiment, since the first wiring 2A and the second wiring 2B have a two-layer structure, the printed circuit board 2 is more compact than the case where the width of the same layer wiring is widened when the measurement target current I is increased. The printed circuit board 2 can be made cheaper than the case where the thickness is increased by wiring in the same layer.

Further, in the configuration examples shown in FIGS. 11 and 12, the width W2A of the first wiring 2A and the width W2B of the second wiring 2B are the same, and the thickness t2A of the first wiring 2A and the thickness t2B of the second wiring 2B are the same. There is. Further, the path length L2A from the connection point with the through hole 26 in the first wiring 2A to the connection point with the through hole 24 is from the connection point with the through hole 26 in the second wiring 2B to the connection point with the through hole 24. It is the same as the path length L2B of.

As a result, when the first wiring 2A and the second wiring 2B 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 2A with the through holes 26 and 24 becomes. , The resistance value between the connection points of the second wiring 2B with the through holes 26 and 24 (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, the widths W2A and W2B may be different, the thicknesses t2A and t2B may be different, the path lengths L2A and L2B may be different, and the first wiring 2A may be different. And the second wiring 2B may be made of different 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 W2A and W2B different as described above. Further, the x-axis direction distance S1 between the outward path portion 21C1 and the return path portion 22C1 in the first wiring 2A shown in FIG. 12 and the x-axis direction distance S2 between the outward path portion 21C2 and the return path portion 22C2 in the second wiring 2B. 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 2A shown in FIG. 12, and between the magnetic field sensor 1 and the second wiring 2B. The current detection sensitivity can be adjusted by adjusting the z-axis direction distance Dz2.

In the present embodiment, the number of the outward path portion and the return path portion (first number) in the first wiring 2A and the number of the outward path portion and the return path portion (second number) in the second wiring 2B are 3 respectively. The number is not limited to one, and may be two or four or more. Further, the first number and the second number do not necessarily have to be the same.

Further, in the printed circuit board 2 of the present embodiment, for example, the same wiring as the second wiring 2B may be added to the third and subsequent layers.

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

FIG. 15 is a schematic view of the measurement target system 1001 according to the first embodiment. The measurement target system 1001 shown in FIG. 15 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. 16 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, in FIG. 16, the one end in the y-axis direction of the outward path portion 21A and the one-side end in the y-axis direction of the return path portion 22A are not directly connected by the connecting portion 23A (FIG. 15). , Connected by the connecting portion 27 via the load Z2. As a result, the measurement target current I flows from the outward path portion 21A to the return path portion 22A via the load Z2.

As a modification of the second embodiment, the return path portion 22A may be connected to the other end in the y-axis direction and the outward path portion 21B to be connected to the other end in the y-axis direction by a connecting portion via a load. ..

Further, in the current detection device 5 (FIG. 11) according to the second embodiment, between one end of the outward path portion 21A1 in the y-axis direction and one end of the return path portion 22A1 in the y-axis direction, or the y-axis of the outward path portion 21A2. The one-sided end in the direction and the one-sided end in the y-axis direction of the return path portion 22A2 may be connected by a connecting portion via a load. Alternatively, between the other end in the y-axis direction of the return path portion 22A1 and the other end in the y-axis direction of the outward path portion 21B1 in the current detection device 5 according to the second embodiment, or the other end in the y-axis direction of the return path portion 22A2. And the other end of the outward path portion 21B2 in the y-axis direction may be connected by a connecting portion via a load.

<6. 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.

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

1 Magnetic field sensor 11 1st magnetic field detector 12 2nd magnetic field detector 13 MI (magnetic impedance) effect element 141 1st sample / hold part 142 2nd sample / hold part 151 1st amplifier part 152 2nd amplifier part 16 Subtraction part 17 Oscillator 18 Pulse drive 2 Printed circuit board 2A wiring (first wiring)
2B 2nd wiring 21A to 21C, 21A1 to 21C1, 21A2 to 21C2 Outward route 22A to 22C, 22A1 to 22C1, 22A2 to 22C2 Return route 23A to 23E, 23A1 to 23E1, 23A2 to 23E2 Connection part 24 Through hole 25 Output wiring 26 Through hole 27 Connection part 5 Current detector 1001, 1002 Measurement target system E Power supply Z, Z1, Z2 Load

Claims (12)

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 the first wiring of the same layer and has.
The first wiring includes a plurality of outward paths extending in the second direction and arranged in the first direction, and a plurality of return paths extending in the second direction and arranged in the first direction. ,
The plurality of return paths are arranged on one side of the first direction with respect to the plurality of outward paths.
The first magnetic field detection unit is arranged in a first second direction region in which the plurality of outward path portions overlap when viewed in the first direction in a plan view of a plane including the first direction and the second direction.
The second magnetic field detection unit is arranged in a second second direction region in which the plurality of return paths overlap in the first direction in the plan view.
Current detector. Assuming that the plurality of outward paths are the mth outward path (m = 1 to n) and the plurality of return paths are the m return paths (m = 1 to n) (n: an integer of 3 or more).
The first outbound route portion to the nth outbound route portion are arranged in order on one side in the first direction.
The first return path section to the nth return path section are arranged in order on the other side in the first direction.
With m being 2 or more, the one-sided end in the second direction of the m-outward route portion and the one-sided end in the second direction of the m-return route portion are connected in the first direction.
According to claim 1, where m is 2 or more, the other end in the second direction of the m return path portion and the other end in the second direction of the (m + 1) outward path portion are connected in the first direction. The current detector described. The substrate is
In the plan view, the output wiring that crosses the first to first (n-1) return paths in the second direction and
The current detection device according to claim 2, further comprising a through hole extending in the third direction by electrically connecting the other end of the n-th return path portion in the second direction and the output wiring. The substrate is arranged on the other side of the third direction from the first wiring and further has a second wiring of the same layer.
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 second wiring includes a plurality of lower outward paths extending in the second direction and arranged in the first direction, and a plurality of lower return paths extending in the second direction and arranged in the first direction. And, including
The plurality of lower return paths are arranged on one side of the first direction with respect to the plurality of lower outward paths.
The first magnetic field detection unit is arranged in a third second direction region in which the plurality of lower outward path portions overlap when viewed in the first direction in the plan view.
Any of claims 1 to 3, wherein the second magnetic field detection unit is arranged in a fourth second direction region in which the plurality of lower return paths overlap when viewed in the first direction in the plan view. The current detection device according to item 1. The plurality of lower outward paths are defined as the m lower outward path (m = 1 to l), and the plurality of lower return sections are designated as the m lower return path (m = 1 to l) (l: 3 or more). Integer)
The first lower outbound route portion to the l lower outbound route portion are arranged in order on one side in the first direction.
The first lower return section to the first lower return section are arranged in order on the other side in the first direction.
With m being 2 or more, the one-sided end in the second direction of the lower m lower outbound route and the one-sided end in the second direction of the lower m lower inbound route are connected in the first direction.
When m is 2 or more, the other end in the second direction of the lower return path portion of m and the other end in the second direction of the (m + 1) lower outward path portion are connected in the first direction. The current detection device according to claim 4. The substrate is
In the plan view, the output wiring that crosses the first to first (n-1) lower return paths in the second direction, and
The current detection device according to claim 5, further comprising a through hole extending in the third direction by electrically connecting the other end of the second lower return path portion in the second direction and the output wiring.
Current detector. The width of the outward path portion and the width of the return path portion are the same first width.
The width of the lower outward path portion and the width of the lower return path portion are the same second width.
The current detection device according to any one of claims 4 to 6, wherein the first width and the second width are different. The first-direction distance between the outward path portion arranged at one side end in the first direction and the return path portion arranged at the other end in the first direction.
The first direction distance between the lower outward path portion arranged at one side end of the first direction and the lower return path portion arranged at the other side end of the first direction is different from the claim. The current detection device according to any one of claims 4 to 7. The current detection device according to any one of claims 4 to 8, 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 4 to 9, wherein the lower outward path portion and the lower return path portion are connected by a connecting portion via a load. The current detection device according to any one of claims 1 to 10, wherein the outward path portion and the return path portion are connected by a connecting portion via a load. The current detection device according to any one of claims 1 to 11, 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.

Images