JP5488423B2 - Magnetic field detector - Google Patents

Description

  The present invention relates to a shielded loop antenna type magnetic field detector.

  2. Description of the Related Art Conventionally, a shielded loop antenna type magnetic field detector is known as a magnetic field detector for measuring a current flowing through a wiring of a printed circuit board (a magnetic field caused by the current). Moreover, as such a magnetic field detector, as described in Patent Document 1, for example, an insulating base material (insulating layer), a conductor pattern provided in multiple layers on the insulating base material in the thickness direction of the insulating base material, 2. Description of the Related Art A shielded loop antenna is known in which a multilayer substrate having an interlayer connection (via conductor) that electrically connects conductor patterns is formed.

  In a conventional shielded loop type magnetic field detector represented by Patent Document 1, a conductor pattern constituting a loop portion is provided perpendicular to an insulating base material in a thickness direction (hereinafter simply referred to as a thickness direction). And has a gap in the vicinity of the center of the long side portion on the surface side of the multilayer board facing the wiring formation surface of the printed board. The longitudinal side portion having the gap has a longitudinal direction (hereinafter simply referred to as a longitudinal direction) parallel to the surface of the multilayer substrate facing the wiring formation surface of the printed circuit board. For this reason, the distance between the wiring of the printed circuit board and the long side portion having the gap is substantially constant in the longitudinal direction, and the magnetic field can be detected with high accuracy.

JP 2007-155597 A

  In recent years, with the spread and diversification of electronic devices, the harmful effects of electromagnetic noise have become a problem, and it is possible to grasp the electric field and magnetic field distribution status of each device in light of the usage environment and driving conditions of each device. It has been demanded. Thus, from the viewpoint of electromagnetic noise suppression, so-called EMC (Electro-Magnetic Compatibility), there is a need to measure a current (magnetic field) in addition to the above-described printed circuit board wiring.

  For example, a vehicle is equipped with electronic devices of various frequency bands, and it is considered that current flows through the vehicle surface (body) when an in-vehicle wireless device is operated, which affects radio wave emission characteristics around the vehicle. For this reason, there is a new need to measure the current (magnetic field) flowing on the vehicle surface. In this way, a variety of measurement objects are available.

  However, the conventional shielded loop type magnetic field detector represented by Patent Document 1 is originally intended for measuring the current flowing through the wiring of the printed circuit board. Therefore, although the surface is suitable for a measurement object having a flat surface, when the surface is a measurement object having a curved surface, such as a vehicle surface, the distance between the curved surface (the surface of the measurement object) and the long side portion having the gap is the longitudinal direction. In this case, the detection accuracy of the magnetic field is lowered as compared with the flat surface. That is, it is not suitable for a measurement object other than a plane.

  Further, in the shielded loop magnetic field detector represented by Patent Document 1, as described above, the conductor pattern having a gap is perpendicular to the thickness direction, that is, the loop surface of the loop portion of the shielded loop antenna is thick. It is perpendicular to the direction. Therefore, even if the multilayer substrate has flexibility in the thickness direction, the measurement is performed by bending the multilayer substrate in the direction perpendicular to the thickness direction, that is, in the direction parallel to the loop surface of the loop portion of the shielded loop antenna. It cannot be in close contact with the subject. For this reason, the distance between the measurement object and the long side having the gap is not constant. In Patent Document 1, since the insulating base material is made of a ceramic sheet, it is difficult to bring the multilayer substrate into close contact with the measurement target.

  In view of the above problems, an object of the present invention is to provide a shielded loop antenna type magnetic field detector capable of accurately detecting a magnetic field regardless of the surface shape of a measurement target. In other words, an object of the present invention is to provide a shielded loop antenna type magnetic field detector capable of detecting a magnetic field with high accuracy even for a measurement object having a curved shape.

  In order to achieve the above object, in the invention according to claim 1, the multilayer substrate has flexibility in the thickness direction because the insulating base material contains at least a resin as a constituent material. The loop surface formed by the loop portion of the shielded loop antenna is parallel to the thickness direction, and the conductor pattern having a gap is parallel to the surface perpendicular to the thickness direction of the multilayer substrate facing the object to be measured. The portion is composed of a conductor pattern and an interlayer connection.

  Therefore, the multilayer substrate (magnetic field detector) can be brought into close contact with the measurement target and the multilayer substrate can be bent. At this time, since the multilayer substrate bends following the surface shape of the measurement target, the distance between the conductor pattern having a gap and the measurement target is substantially constant in the longitudinal direction of the conductor pattern regardless of the surface shape of the measurement target. can do. Therefore, the magnetic field can be detected with high accuracy regardless of the surface shape of the measurement target. For example, it is possible to accurately detect a magnetic field not only for a planar shape measurement object but also for a curved surface measurement object.

  In the invention described in claim 2, the signal conductor portion has a loop shape which is parallel to the thickness direction. In addition, an inner conductor portion provided inside the loop of the signal conductor portion so that the constant potential conductor portion constituting the loop portion of the shielded loop antenna faces the signal conductor portion, and a signal conductor portion, It has an outer conductor portion provided outside the loop of the signal conductor portion so as to face each other. The inner conductor portion and the outer conductor portion are electrically connected and each have a conductor pattern having a gap so that the gap faces each other.

  Thus, if the constant potential conductor portion fixed to a constant potential such as the ground has at least the inner conductor portion and the outer conductor portion arranged so as to sandwich the signal conductor portion, the magnetic flux interlinking with the loop portion is generated. Can be detected. Further, when the multilayer board is bent, the conductor pattern having the gap of the outer conductor portion, the conductor pattern of the signal conductor portion, and the conductor pattern having the gap of the inner conductor portion are also bent in the thickness direction. The positional relationship can be maintained. Thereby, the magnetic field can be detected with high accuracy.

  In addition, since the signal conductor portion has a loop shape, the external electric field can be compared with a configuration in which the signal conductor portion is approximately half the loop shape, such as a substantially U shape or a substantially C shape (semicircular shape). The voltage of the external electric field can be reduced to a very small value with respect to the voltage output of the magnetic field. That is, the electric field can be shielded.

  In the invention according to claim 3, the inner conductor portion and the outer conductor portion are electrically connected by the interlayer connection portion, and at least a part of the constant potential conductor portion is cylindrical. The cylindrical portion surrounds the signal conductor portion over a predetermined range. As described above, when the constant potential conductor portion is provided with the cylindrical portion, the influence of the external electric field can be reduced due to the shielding effect of the cylindrical portion.

  In particular, as described in claim 4, the portion of the constant potential conductor portion excluding the gap is formed into a cylindrical shape, and only the portion corresponding to the gap of the signal conductor portion is positioned outside the cylinder of the constant potential conductor portion. Thus, the magnetic field can be detected, and the influence of the external electric field can be reduced more effectively.

  On the other hand, as described in claim 5, the constant potential conductor portion has a plurality of cylindrical portions, and a part of the portion excluding the portion corresponding to the gap in the signal conductor portion is in the plurality of cylindrical portions. If it is set as the structure located in, it can reduce the influence of an external electric field more effectively. In addition, the flexibility of the multilayer substrate can be improved as compared with the configuration in which the entire region excluding the gap of the constant potential conductor is cylindrical.

  More specifically, as described in claim 6, a loop-shaped signal conductor portion is formed by a six-layer conductor pattern and each interlayer connection portion (first interlayer connection portion to seventh interlayer connection portion), The constant potential conductor portion surrounding the signal conductor portion except for the gap can be formed on a multilayer substrate.

  In the invention described in claim 7, the insulating base material is constituted by laminating and integrating a plurality of base material films so that the base material film containing the thermoplastic resin is positioned at least every other layer. The interlayer connection portion includes an interlayer connection via. According to this, the magnetic field detector can be formed by a batch lamination method known as PALAP. That is, the manufacturing process can be simplified. PALAP is a registered trademark of Denso Corporation.

  In the invention described in claim 8, a plurality of shielded loop antennas are formed on the same multilayer substrate so that the loop surfaces are orthogonal to each other. Thus, when the magnetic field detector for two-axis detection or three-axis detection is configured by one multilayer substrate, the direction of the magnetic field can be detected.

It is a top view which shows schematic structure of the magnetic field detector which concerns on 1st Embodiment. It is sectional drawing which follows the II-II line | wire of FIG. It is a perspective view which shows schematic structure of a multilayer substrate part among magnetic field detectors. It is the perspective view which looked at FIG. 3 from the back side. It is a permeation | transmission figure which shows the loop-shaped signal conductor part comprised in the multilayer substrate. It is sectional drawing which follows the VI-VI line of FIG.2 and FIG.3. It is sectional drawing which follows the VII-VII line of FIG.2 and FIG.3. It is sectional drawing which follows the VIII-VIII line of FIG.2 and FIG.3. It is sectional drawing which follows the IX-IX line of FIG.2 and FIG.3. It is a figure which shows a magnetic field detection characteristic. It is a top view which shows schematic structure of the magnetic field detector which concerns on 2nd Embodiment. It is a perspective view which shows a modification.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In each embodiment, common or related elements are given the same reference numerals.
(First embodiment)
In the following, the thickness direction of the insulating base material 20 (multilayer substrate 11) is simply referred to as the thickness direction. Of the directions perpendicular to the thickness direction, the arrangement direction of the pair of electrode patterns 30a is simply referred to as an arrangement direction. The width of each conductor pattern 21 indicates the width in the direction perpendicular to the thickness direction and the arrangement direction.

  As shown in FIGS. 1 to 9, the magnetic field detector 10 includes a multilayer substrate 11 having a shield dead loop antenna. In other words, the magnetic field detector 10 is provided with a shielded loop antenna having a stripline structure. In the present embodiment, the magnetic field detector 10, together with the multilayer substrate 11, has an impedance between a shield case 12 that shields a pair of electrode patterns 30 a and a chip resistor 13 described later from external noise (electromagnetic waves), and a coaxial cable 14 that is described later. A chip resistor 13 for matching is provided. FIG. 2 shows the coaxial cable 14 connected to the shielded loop antenna. In the cross-sectional views shown in FIGS. 6 and 7, the shield case 12 of FIG. 2 is omitted.

  The multilayer substrate 11 includes an insulating base material 20 containing at least a resin, conductor patterns 21 arranged in a multilayer on the insulating base material 20 in the thickness direction, and the conductive patterns 21 of different layers arranged on the insulating base material 20 electrically. Interlayer connection part 22 connected to

  As the insulating base material 20, it is preferable to adopt a structure in which a plurality of base material films are laminated and integrated so that at least every other base material film containing a thermoplastic resin is positioned. As the base film containing the thermoplastic resin, a film applicable to a batch lamination method known as so-called PALAP can be employed. According to this, the insulating base material 20 and by extension, the multilayer substrate 11 can be formed in a lump by laminating a plurality of base material films and heating the laminated body from above and below in the laminating direction. In addition to the collective stacking, a build-up substrate formed by stacking one by one can also be employed.

  In this embodiment, twelve base films having the same thickness are laminated and integrated to form an insulating base 20, and all base films include 30% by weight of polyetheretherketone (PEEK) and polyetherimide. (PEI) The resin film which consists of 70 weight% is employ | adopted.

  The conductor pattern 21 can be formed by patterning a metal foil or formed by plating, screen printing, or the like. When adopting the above-described collective laminating method, it is possible to employ a conductor pattern 21 formed by patterning a metal foil attached to one or both sides of a base film.

  In this embodiment, the conductor pattern 21 formed by patterning the copper foil affixed on the base film is employed. Moreover, as shown in FIG. 2, it has the 6-layer conductor pattern 21 of the same thickness. Specifically, as the six-layer conductor pattern 21, the first conductor pattern 30, the second conductor pattern 31, the third conductor pattern 32, and the fourth conductor pattern 21 from the surface side opposite to the surface on the measurement target side in the insulating base material 20 in the thickness direction. The conductor pattern 33, the fifth conductor pattern 34, and the sixth conductor pattern 35 are arranged in this order. As shown in FIG. 3, the first conductor pattern 30 is disposed on one surface 20 a of the insulating substrate 20, and the sixth conductor pattern 35 is disposed on the surface 20 b opposite to the one surface 20 a of the insulating substrate 20. These conductor patterns 21 (30 to 35) all extend in the arrangement direction.

  As shown in FIGS. 1 to 3, the first conductor pattern 30 includes a pair of electrode patterns 30 a, an inner conductor pattern 30 b disposed so as to straddle the opposing region of the pair of electrode patterns 30 a, an electrode pattern 30 a, It has the outer side conductor pattern 30c arrange | positioned so that the inner side conductor pattern 30b may be surrounded, and the both ends of the inner side conductor pattern 30b were connected. Specifically, the planar rectangular electrode pattern 30a is arranged in line symmetry with respect to the inner conductor pattern 30b extending along the direction perpendicular to the thickness direction and the arrangement direction, and the electrode pattern 30a, the inner conductor pattern 30b, and the outer conductor The portion around the electrode pattern 30a defined by the pattern 30c (the portion without the first conductor pattern 30) is a rectangular ring.

  The fourth conductor pattern 33 and the sixth conductor pattern 35 have gaps 33g and 35g, respectively, so that the projection positions on the same plane perpendicular to the thickness direction overlap each other. The gaps 33 g and 35 g are slit portions without the conductor pattern 21. In the present embodiment, the extending direction of the slit is parallel to the inner conductor pattern 30b.

  The outer conductor pattern 30 c and the third conductor pattern 32 are wider than the second conductor pattern 31, and the fourth conductor pattern 33 and the sixth conductor pattern 35 are wider than the fifth conductor pattern 34. This is because the constant potential conductor portion 24 described later constitutes a cylindrical portion together with the interlayer connection portion 22 (45, 46), and the signal conductor portion 23 is disposed inside the cylinder. In addition, the width | variety of each conductor pattern 21 is a width | variety of the direction perpendicular | vertical to the thickness direction and a row direction.

  In the present embodiment, the second conductor pattern 31 and the fifth conductor pattern 34 have a constant width as shown in FIGS. 5, 7, and 8, and the widths are substantially equal to each other. As shown in FIGS. 2 and 5, a pair of second conductor patterns 31 are provided corresponding to the pair of electrode patterns 30a, and the pair of conductor patterns 31 is connected to a first interlayer connection portion 40 described later. From the connection part, it extends in a direction opposite to each other in the arrangement direction. Further, the fourth conductor pattern 33 and the sixth conductor pattern 35 are all constant in width as shown in FIGS. 4, 7, and 8, and are substantially equal to each other. As shown in FIGS. 6 to 8, the third conductor pattern 32 has a portion in a predetermined range from both ends of the multilayer substrate 11 in the arrangement direction that is substantially equal to the width of the fourth conductor pattern 33 and is close to the electrode pattern 30 a. The remaining portion is wider than the fourth conductor pattern 33. Such a shape is apparent from the arrangement of the sixth interlayer connection portion 45 indicated by a broken line in FIG. As shown in FIGS. 3 and 6 to 9, the outer conductor pattern 30 c has a predetermined range from the both ends of the multilayer substrate 11 in the arrangement direction, and is substantially equal to the width of the fourth conductor pattern 33. The remaining part close to is an annular part surrounding the electrode pattern 30a and the inner conductor pattern 30b. As shown in FIG. 7, in the thickness direction and in the direction perpendicular to the arrangement direction, the inner diameter of the annular portion of the outer conductor pattern 30c is slightly shorter than the wider portion of the third conductor pattern 32, and the outer diameter is the first. It is longer than the wide portion of the three conductor pattern 32. Such a shape is apparent from the arrangement of the sixth interlayer connection portion 45 indicated by a broken line in FIG.

  The interlayer connection part 22 includes at least an interlayer connection via 22a penetrating the base film. In this embodiment, the land 22b formed by patterning the metal foil formed in the one or both surfaces of the base film is also included with the interlayer connection via 22a. Further, as the interlayer connection via 22a, a conductive paste filled in the through hole of the base film is sintered when the laminated base film is pressed and heated. The interlayer connection via 22a and the conductor pattern 21 are connected by this sintering. When the interlayer connection vias 22a are in contact with each other, the interlayer connection vias 22a are connected.

  As shown in FIGS. 2 to 4 and FIGS. 6 to 9, as the interlayer connection portion 22, the first interlayer connection portion 40 and the second conductor pattern that connect the corresponding electrode pattern 30 a and the second conductor pattern 31. And a second interlayer connection portion 41 for connecting 31 and the fifth conductor pattern 34. Further, a third interlayer connection portion 42 that connects the inner conductor pattern 30 b and the third conductor pattern 32, and a fourth interlayer connection portion 43 that connects the third conductor pattern 32 and the fourth conductor pattern 33 are provided. In addition, a fifth interlayer connection portion 44 that connects the outer conductor pattern 30c and the sixth conductor pattern 35, a sixth interlayer connection portion 45 that connects the outer conductor pattern 30c and the third conductor pattern 32, a fourth conductor pattern 33 and a sixth conductor pattern. A seventh interlayer connection 46 for connecting the conductor pattern 35 is provided.

  As shown in FIGS. 2 and 5, the first interlayer connection portion 40 has one end connected to the end portion on the electrode pattern 30 a side of the pair of second conductor patterns 31 in the arrangement direction, and the other end corresponding to the electrode. It is connected to the pattern 30a. As shown in FIGS. 2, 5, and 9, one end of each of the second interlayer connection portions 41 is connected to the opposite end of the pair of second conductor patterns 31 from the first interlayer connection portion 40. The ends are respectively connected to both ends of the corresponding fifth conductor pattern 34. As shown in FIGS. 2, 3, and 6, the third interlayer connection portion 42 has one end connected to almost the entire area of the inner conductor pattern 30b in the thickness direction and the direction perpendicular to the alignment direction, and the other end connected to the second end. The three conductor patterns 32 are connected to almost the entire area. As shown in FIG. 2, the fourth interlayer connection portion 43 connects both ends of the third conductor pattern 32 and the fourth conductor pattern 33 in the arrangement direction. Although not shown, the fourth interlayer connection portion 43 is also connected to substantially the entire area of the third conductor pattern 32 and the substantially entire area of the fourth conductor pattern 33 in the thickness direction and in the direction perpendicular to the arrangement direction. As shown in FIGS. 2 to 4 and 9, the fifth interlayer connection portion 44 connects both end portions of the outer conductor pattern 30 c and the sixth conductor pattern 35 in the arrangement direction. Although not shown, the fifth interlayer connection 44 is also connected to almost the entire area of the outer conductor pattern 30c and the almost entire area of the sixth conductor pattern 35 in the thickness direction and in the direction perpendicular to the arrangement direction. Further, as shown in FIGS. 3 and 4, it is provided up to the position of the fourth interlayer connection portion 43 in the arrangement direction. As shown in FIGS. 3, 4, 7, and 8, the sixth interlayer connection 45 and the seventh interlayer connection 46 are arranged in the arrangement direction from one fourth interlayer connection 43 to the other fourth interlayer connection. Part 43 is provided.

  Further, the third interlayer connection portion 42 and the sixth interlayer connection portion 45 are connected, and the sixth interlayer connection portion 45 and the fifth interlayer connection portion 44 are connected. Also, the fourth interlayer connection 43 and the fifth interlayer connection 44 are connected, and the fifth interlayer connection 44 and the seventh interlayer connection 46 are connected.

  The conductor pattern 21 and the interlayer connection portion 22 constitute a signal conductor portion 23 that forms a conductor portion of the shielded loop antenna and a constant potential conductor portion 24 that is fixed to a constant potential such as a ground. Yes.

  The signal conductor portion 23 is linearly formed by the electrode pattern 30 a as the first conductor pattern 30, the first interlayer connection portion 40, the second conductor pattern 31, the second interlayer connection portion 41, and the fifth conductor pattern 34. It is comprised as a conductor part. The signal conductor portion 23 has a loop shape, and the loop-shaped forming surface is parallel to the thickness direction. In this embodiment, it is parallel to the thickness direction and the alignment direction.

  The constant potential conductor 24 includes an inner conductor portion 24 a provided inside the loop of the signal conductor portion 23 so as to face the signal conductor portion 23, and a signal conductor so as to face the signal conductor portion 23. The outer conductor portion 24 b is provided outside the loop of the portion 23. The conductor portions 24a and 24b are electrically connected and have conductor patterns 33 and 35 having gaps 33g and 35g, respectively, so that the gaps 33g and 35g face each other. And the signal conductor part 23 is arrange | positioned in the opposing area | region of the inner side conductor part 24a and the outer side conductor part 24b. That is, the signal conductor portion 23 is sandwiched between the inner conductor portion 24a and the outer conductor portion 24b with the insulating base material 20 interposed therebetween.

  The inner conductor portion 24a includes an inner conductor pattern 30b, a third interlayer connection portion 42, a third conductor pattern 32, a fourth interlayer connection portion 43, and a fourth conductor pattern 33 having a gap 33g. On the other hand, the outer conductor portion 24b includes an outer conductor pattern 30c, a fifth interlayer connection portion 44, and a sixth conductor pattern 35 having a gap 35g.

  And these conductor parts 24a and 24b have comprised the above-mentioned 6th interlayer connection part 45 and the 7th interlayer connection part 46, and have comprised the cylinder shape. That is, the constant potential conductor portion 24 is provided in a cylindrical shape and includes the signal conductor portion 23. Specifically, one end of the cylindrical portion surrounds and opens one electrode pattern 30a, and the other end surrounds and opens the other electrode pattern 30a, and the signal conductor portion 23 (fifth in the center of the cylindrical portion). An annular gap surrounding the fifth conductor pattern 34 is provided to expose the conductor pattern 34) from the cylindrical portion. Further, the loop surface of the loop portion formed by the constant potential conductor portion 24 (strictly speaking, since there is a gap, the loop portion) is parallel to the thickness direction. In this embodiment, it is parallel to the thickness direction and the alignment direction.

  In the thickness direction, the opposing distance between the second conductor pattern 31 constituting the signal conductor portion 23 and the outer conductor pattern 30c constituting the outer conductor portion 24b, and the second conductor pattern 31 and the inner conductor portion 24a are constituted. The facing distance to the third conductor pattern 32 is equal. The opposing distance between the fifth conductor pattern 34 constituting the signal conductor portion 23 and the sixth conductor pattern 35 constituting the outer conductor portion 24b, and the fourth conductor constituting the fifth conductor pattern 34 and the inner conductor portion 24a. The opposing distance to the pattern 33 is equal. Further, in the direction perpendicular to the thickness direction, the opposing distance between the second interlayer connection portion 41 constituting the signal conductor portion 23 and the fifth interlayer connection portion 44 constituting the outer conductor portion 24b, and the second interlayer connection portion 41 and the fourth interlayer connection portion 43 constituting the inner conductor portion 24a are equal to each other.

  In the magnetic field detector 10 configured as described above, the surface 20b of the multilayer substrate 11 is brought into close contact with the surface of the measurement target in order to detect the magnetic field of the measurement target. The voltage generated according to the magnetic flux passing through the loop surface formed by the constant potential conductor portion 24 can be detected via the coaxial cable 14. That is, the current flowing through the measurement object can be detected. In the present embodiment, the central conductor of the coaxial cable 14 is connected to one electrode pattern 30 a of the signal conductor portion 23, and the external conductor is connected to the outer conductor pattern 30 c of the low potential conductor portion 24. However, it is also possible to extract a voltage from the two electrode patterns 30a of the signal conductor portion 23.

  Next, the effect of the characteristic part of the magnetic field detector 10 having the above configuration will be described.

  In the present embodiment, the insulating base material 20 constituting the multilayer substrate 11 includes at least a resin as a constituent material, whereby the multilayer substrate 11 has flexibility in the thickness direction. Also, a conductor pattern having a loop surface formed by the loop portion of the shielded loop antenna (low potential conductor portion 24) parallel to the thickness direction and having gaps 33g and 35g with respect to the surface 20b of the multilayer substrate facing the measurement object. 33 and 35 are comprised so that it may become parallel.

  Therefore, the multilayer substrate 11 can be bent in the thickness direction when the surface 20b of the multilayer substrate 11 is brought into close contact with the measurement target and the magnetic field (current) of the measurement target is detected. At this time, since the multilayer substrate 11 bends following the surface shape of the measurement target, the distance between the conductor patterns 33 and 35 having the gaps 33g and 35g and the measurement target is set in the alignment direction (regardless of the surface shape of the measurement target. It can be made substantially constant in the longitudinal direction of the conductor patterns 33 and 35. Therefore, the magnetic field can be detected with high accuracy regardless of the surface shape of the measurement target. According to this, it is possible to accurately detect the magnetic field not only for a measurement target having a flat surface but also for a measurement target having a curved surface. For example, the current flowing through the vehicle body can also be detected.

  Particularly in the present embodiment, when projected onto the same plane perpendicular to the thickness direction, the sixth conductor pattern 35 having the gap of the outer conductor portion 24b, the fifth conductor pattern 34 of the signal conductor portion 23, and the inner conductor portion 24a. The conductor patterns 33 to 35 are stacked in the thickness direction so that the fourth conductor patterns 33 having the gaps overlap. Therefore, when the multilayer substrate 11 is bent, the conductor patterns 33 to 35 are bent in the same direction in the thickness direction, so that the mutual positional relationship can be maintained. Thereby, the magnetic field can be detected with high accuracy.

  In addition, the magnetic field detection characteristic of the magnetic field detector 10 shown in this embodiment is shown in FIG. As shown in FIG. 10, the magnetic field intensity varies linearly from 10 MHz to 2 GHz according to the frequency. Specifically, the frequency is 10 times and the magnetic field strength is changed by about 20 dB. Thus, according to the magnetic field detector 10 shown in the present embodiment, a magnetic field can be accurately detected in a wide frequency range.

  In the present embodiment, the signal conductor portion 23 has a loop shape that is parallel to the thickness direction. The inner conductor portion 24a and the outer conductor portion 24b are electrically connected by the sixth interlayer connection portion 45 and the seventh interlayer connection portion 46, and the portion excluding the gap of the constant potential conductor portion 24 has a cylindrical shape. ing. Of the signal conductor portion 23, only the portion corresponding to the gap is located outside the constant potential conductor portion 24. Therefore, the influence of the external electric field can be reduced by the shielding effect by the cylindrical low potential conductor portion 24. In this embodiment, such a configuration is realized by the six layers of conductor patterns 30 to 35 and the interlayer connection portions 40 to 46.

  In addition, since the signal conductor portion 23 has a loop shape, compared to a configuration having the signal conductor portion 23 that is approximately half of the loop shape, such as a substantially U shape or a substantially C shape (semicircular shape), The influence of the external electric field can be canceled, and the voltage due to the external electric field can be set to a very small value with respect to the voltage output due to the magnetic field. That is, the electric field can be shielded.

(Second Embodiment)
In the first embodiment, an example of the magnetic field detector 10 in which one shielded loop antenna is configured on the multilayer substrate 11 is shown. That is, the uniaxial magnetic field detector 10 is shown.

  On the other hand, in the present embodiment, a plurality of shielded loop antennas are configured on the same multilayer substrate 11 so that the loop surfaces are orthogonal to each other, that is, a multi-axis magnetic field detector 10 is configured. It is characterized by.

  For example, in FIG. 11, with respect to three axes x, y, and z orthogonal to each other, a shield dead loop antenna S1 whose loop surface is perpendicular to the x axis, a shield dead loop antenna S2 whose loop surface is perpendicular to the y axis, and the loop surface is z Three shielded loop antennas S3 perpendicular to the axis are formed on the same multilayer substrate 11. The z-axis direction is the thickness direction. According to this configuration, the multilayer substrate 11 is brought into close contact with the measurement target, and the multilayer substrate 11 is bent in the thickness direction, whereby the distance between the conductor pattern having the gap between the shielded dead-loop antennas S1 and S2 and the measurement target is determined. It can be made substantially constant in the longitudinal direction of the pattern. It is also possible to detect the direction (vector) of the magnetic field. In FIG. 11, three shielded dead loop antennas S1, S2 and S3 are shown, but a biaxial magnetic field detector 10 having only two shielded dead loop antennas S1 and S2 whose loop surfaces are parallel to the thickness direction is employed. You can also

  The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention.

  In the first embodiment, for example, as shown in FIG. 3, in the thickness direction and the direction perpendicular to the arrangement direction, the width of the multilayer substrate 11 is set to a portion surrounding the electrode pattern 30 a and an end portion in the arrangement direction than the surrounding portion. It is different from the side part, and a thin example is shown at the end side part. However, as shown in FIG. 12, for example, a flat rectangular multi-layer substrate 11 is adopted, and a portion of one surface 20a excluding the electrode pattern 30a, the inner conductor pattern 30b, and a portion (extracted portion) that partitions the electrode pattern 30a. All may be the outer conductor pattern 30c. According to this, the outer conductor pattern 30c can enhance the effect of shielding the electrode pattern 30a and the chip resistor 13 from external noise (electromagnetic waves). In addition, since the planar rectangular multilayer substrate 11 is employed, the thickness of the insulating base material 20 along the direction perpendicular to the surface formed by the loop shape of the signal conductor portion 23 can be made uniform over the entire arrangement direction. . In other words, the signal conductor portion 23 can be arranged at the center of the insulating base material 20 in the direction perpendicular to the surface formed by the loop shape of the signal conductor portion 23 in the entire arrangement direction. Thereby, the shift | offset | difference of the characteristic impedance in a high frequency by the difference in the thickness of the insulating base material 20 (dielectric material) can be suppressed, and a high frequency characteristic can be improved.

  In the present embodiment, an example in which a portion excluding the portion corresponding to the gap of the signal conductor portion 23 is surrounded by the cylindrical constant potential conductor portion 24 is shown. However, only a part of the portion excluding the portion corresponding to the gap of the signal conductor portion 23 may be surrounded by the cylindrical constant potential conductor portion 24. According to this, due to the shielding effect of the cylindrical portion of the constant potential conductor portion 24, the influence of the external electric field can be reduced to some extent.

  For example, the constant potential conductor portion 24 may have a plurality of cylindrical portions, and a part of the portion other than the portion corresponding to the gap in the signal conductor portion 23 may be positioned within the plurality of cylindrical portions. According to this, the influence of an external electric field can be reduced more effectively. In addition, the flexibility of the multilayer substrate 11 can be improved as compared with the configuration in which the entire region excluding the gap of the constant potential conductor portion 24 is cylindrical. That is, the flexibility of the multilayer substrate 11 can be improved while increasing the length of the cylindrical portion to enhance the shielding effect.

  Furthermore, the constant potential conductor portion 24 may have at least an inner conductor portion 24a and an outer conductor portion 24b arranged so as to sandwich the signal conductor portion 23 therebetween. According to this, it is possible to detect the magnetic flux interlinking with the loop portion of the low potential conductor portion 24.

  As the magnetic field detector 10, the insulating substrate 20 constituting the multilayer substrate 11 includes at least a resin as a constituent material, so that the multilayer substrate 11 has flexibility in the thickness direction. Further, the loop surface formed by the loop portion of the shielded loop antenna is parallel to the thickness direction, and the conductor patterns 33 and 35 having a gap are parallel to the surface 20b of the multilayer substrate 11 opposed to the measurement target. What is necessary is just to be a part comprised by the conductor pattern 21 and the interlayer connection part 22. FIG. For example, the constant potential conductor 24 may be provided so as to sandwich the signal conductor 23 in the direction perpendicular to the thickness direction of the loop-shaped signal conductor 23. However, the positions of the signal conductor portion 23 and the constant potential conductor portion 24 are shifted in the direction perpendicular to the thickness direction. Therefore, depending on the surface shape of the measurement target, the signal conductor portion 23 portion and the constant potential conductor portion 24 are arranged. It is also conceivable that the degree of deflection is different in the part. Therefore, preferably, the constant potential conductor portion 24 including the inner conductor portion 24a and the outer conductor portion 24b described in the above embodiment may be employed.

  For example, as the signal conductor portion 23, a substantially half of the loop shape such as a generally well-known U-shape or C-shape (semicircle) is used. Then, as shown in the above embodiment, the shielded loop antenna corresponding to the signal conductor portion 23 has a loop surface that is parallel to the thickness direction and has a gap with respect to the surface of the multilayer substrate that faces the object to be measured. You may comprise so that a conductor pattern may become parallel.

DESCRIPTION OF SYMBOLS 10 ... Magnetic field detector 11 ... Multilayer substrate 20 ... Insulating base material 21, 30-35 ... Conductor pattern 22, 40-46 ... Interlayer connection part 23 ... Signal conductor part 24 ... Constant potential conductor 24a ... Inner conductor 24b ... Outer conductor 30a ... Electrode pattern 30b ... Inner conductor pattern 30c ... Outer conductor patterns 33g, 35g ... Gap

Claims (8)

In a multilayer substrate having an insulating base, a conductor pattern provided in multiple layers on the insulating base in the thickness direction of the insulating base, and an interlayer connection portion that electrically connects the conductor patterns of different layers, A magnetic field detector comprising a shield dead loop antenna, the conductor pattern having a gap included in a loop portion of the sealed dead loop antenna,
The insulating substrate includes at least a resin as a constituent material,
The multilayer substrate has flexibility in the thickness direction,
A loop surface formed by a loop portion of the shielded loop antenna is parallel to the thickness direction, and a conductor pattern having the gap is parallel to a surface perpendicular to the thickness direction of the multilayer substrate facing the measurement target. In addition, the magnetic field detector is characterized in that the loop portion is constituted by the conductor pattern and the interlayer connection portion. The shielded loop antenna has a constant potential as a conductor portion having the conductor pattern and the interlayer connection portion, and has a constant potential conductor portion and a signal conductor portion constituting the loop portion,
The signal conductor portion has one end connected to one of a pair of electrode patterns provided on the surface opposite to the surface to be measured in the insulating base as the conductor pattern and the other end connected to the other. A loop shape is formed, and the formation surface of the signal conductor portion in the loop shape is parallel to the thickness direction,
The constant-potential conductor portion includes an inner conductor portion provided inside a loop of the signal conductor portion so as to face the signal conductor portion, and the signal conductor so as to face the signal conductor portion. An outer conductor provided outside the loop of the part,
The inner conductor portion and the outer conductor portion are electrically connected and each have a conductor pattern having the gap so that the gap is opposed to each other, and the signal is provided in a facing region of the inner conductor portion and the outer conductor portion. The magnetic field detector according to claim 1, wherein a conductor portion is disposed.   The inner conductor portion and the outer conductor portion are electrically connected by the interlayer connection portion, and at least a part of the constant potential conductor portion is provided in a cylindrical shape, and the cylindrical portion of the constant potential conductor portion The magnetic field detector according to claim 2, wherein the signal conductor portion is surrounded by a predetermined range. The interlayer connection portion is provided in a cylindrical shape except for the gap of the constant potential conductor portion,
4. The magnetic field detector according to claim 3, wherein, of the signal conductor portion, only a portion corresponding to the gap is located outside the cylinder of the constant potential conductor portion. The constant potential conductor portion has a plurality of cylindrical portions,
4. The magnetic field detector according to claim 3, wherein a part of the signal conductor portion excluding a portion corresponding to the gap is located in the plurality of cylindrical portions. The multilayer substrate includes a first conductor pattern, a second conductor pattern, a third conductor pattern, a fourth conductor pattern, a fifth conductor pattern, and a sixth conductor pattern from a surface opposite to the surface to be measured in the insulating base material. Having six layers of the conductor pattern arranged in the order of
On the surface opposite to the surface to be measured in the insulating base material, as the first conductor pattern, the pair of electrode patterns, the inner conductor pattern arranged so as to straddle the opposing region of the pair of electrode patterns, and the An outer conductor pattern is provided so as to surround the electrode pattern and the inner conductor pattern and to which both ends of the inner conductor pattern are connected,
The outer conductor pattern and the third conductor pattern are wider than the second conductor pattern, and the fourth conductor pattern and the sixth conductor pattern are wider than the fifth conductor pattern,
The signal conductor portion includes the pair of electrode patterns, a pair of first interlayer connection portions connected to each electrode pattern as the interlayer connection portion, and one end connected to the first interlayer connection portion and facing each other. A pair of second conductor patterns extending to the end, a pair of second interlayer connections connected to an end of each second conductor pattern far from the electrode pattern as the interlayer connection, and the pair of second The fifth conductor pattern provided opposite to the conductor pattern and connected to the second interlayer connection portions at both ends, and
An inner conductor part of the constant potential conductor part is connected to the inner conductor pattern, a third interlayer connection part connected to the inner conductor pattern as the interlayer connection part, and a part of the third interlayer connection part. The third conductor pattern provided opposite to the second conductor pattern, a pair of fourth interlayer connection portions connected to both ends of the third conductor pattern as the interlayer connection portions, and the third conductor pattern And the fourth conductor pattern as the conductor pattern having the gap, the fourth interlayer connection portion being connected to both ends of the fourth interlayer connection portion.
The outer conductor portion of the constant potential conductor portion includes a pair of the outer conductor pattern provided partially facing the second conductor pattern, and a pair of layers connected to both ends of the outer conductor pattern as the interlayer connection portion. A fifth interlayer connection portion, and a sixth conductor pattern as a conductor pattern having the gap, provided opposite to the fifth conductor pattern and having the fifth interlayer connection portion connected to both ends, respectively. And
The constant potential conductor portion includes a sixth interlayer connection portion that electrically connects the outer conductor pattern and the third conductor pattern as the interlayer connection portion, and the fourth conductor pattern and the sixth as the interlayer connection portion. A seventh interlayer connection for electrically connecting the conductor pattern, the third interlayer connection and the sixth interlayer connection are connected, and the sixth interlayer connection and the fifth interlayer connection are The fourth interlayer connection portion and the fifth interlayer connection portion are connected, the fifth interlayer connection portion and the seventh interlayer connection portion are connected, and a portion excluding the gap is provided in a cylindrical shape. The magnetic field detector according to claim 4. The insulating base material is formed by laminating and integrating a plurality of base material films so that a base material film containing a thermoplastic resin is positioned at least every other layer.
The magnetic field according to claim 1, wherein the interlayer connection part includes an interlayer connection via formed by sintering a conductive paste filled in the through hole of the base film. Detector.   The magnetic field detector according to any one of claims 1 to 7, wherein a plurality of the shielded loop antennas are configured on the same multilayer substrate so that their loop surfaces are orthogonal to each other.

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