JP4677861B2 - AC current detection coil - Google Patents

Description

  The present invention relates to an alternating current detection coil formed on an insulating substrate that functions as a current sensor for measuring a current flowing in a branch circuit of a domestic distribution board.

  Generally, a through-type current sensor is often used as a current sensor for measuring the amount of alternating current applied to a power transmission / transformation device, a home distribution board, or the like in a contacted manner. Conventional examples of an alternating current detecting coil used in such a through-type current sensor are shown in FIGS. 14 and 15 (see Patent Document 1). In these figures, an alternating current detection coil 100 includes a double-sided laminated substrate 102 (hereinafter referred to as a printed board) having a circular substrate opening 101, and a coil body 103 disposed around the substrate opening 101. It is an air core coil provided with. The material of the printed circuit board 102 is a glass-filled epoxy resin. The coil main body 103 includes a conductive portion of a conductive film printed radially around the substrate opening 101, and this conductive portion is connected via a connection portion that penetrates in the thickness direction of the printed circuit board 102, that is, in the axial direction of the coil main body 103. Coils are formed on the printed circuit board 102 by being coupled in series. The connection portion is a through hole of a conductive film formed on the inner surface of the through hole of the printed board 102. A coil wound around the printed circuit board 102 is wound at a constant pitch in two directions, and a clockwise winding coil 105 (in the direction of arrow 104) and a counterclockwise winding (in the direction of arrow 106) rewinding coil 107; The coils 105 and 107 are connected in series by connecting the end of the winding coil 105 and the starting end of the rewinding coil 107. In FIG. 15, the winding advance coil 105 has a conductor portion formed on the front surface of the printed circuit board 102 indicated by a thick solid line, and a conductor portion formed on the back surface is indicated by a thick broken line. The conductor portion formed on the back surface is indicated by a double solid line, and the conductor portion formed on the back surface is indicated by a double broken line. On the front and back surfaces of the printed circuit board 102, the conductor portions of the coils 105 and 107 are alternately arranged at a constant pitch. In the winding advance coil 105, conductor portions having different lengths are alternately arranged at a constant pitch on the front and back surfaces, and in the rewinding coil 107, conductor portions having different lengths on the front surface and the back surface are alternately arranged at a constant pitch. It is arranged. Further, in the winding-up coil 105, the pitch between the conductor portions is connected by a connecting portion (through hole) on the side away from the substrate opening 101, and in the rewinding coil 107, each conductor portion is open to the substrate. The pitch of each conductor part is connected by the connection part in the near side of the part 101. FIG.

  In current measurement using such an alternating current detection coil 100, a conductor to be measured through which current flows is passed through the substrate opening 101, and the magnetic flux generated by this current is indicated by the arrow 104 or the arrow on the printed circuit board 102 of both coils 105 and 107. An induced current generated by passing through a cross-sectional area surrounded by the conductor when viewed from the direction of 106 is detected. On the other hand, when viewed in the axial direction of the coil body 103, a magnetic flux of an external magnetic field normally passes through the front area of the region surrounded by the conductor portions of the coils 105 and 107. This external magnetic field is unnecessary for the original current measurement. However, since both the coils 105 and 107 formed in a circle are equivalently regarded as one large coil, if an unnecessary external magnetic field passes within their front area, the current caused by the external magnetic field is also reduced. It is detected at the same time. Since the detection current due to the external magnetic field becomes a measurement error, it is desirable that the influence be as small as possible. In order to suppress this measurement error, it is necessary to cancel the unnecessary detection current by making the front areas of the coils 105 and 107 whose winding directions are opposite to each other with respect to the external magnetic field equal.

  However, in the conventional current sensor, when the coils 105 and 107 are viewed in the axial direction, the front area of the winding advance coil 105 is larger than the front area of the rewinding coil 107, and the respective front areas are different. . Accordingly, the detected amount of the induced current due to the external magnetic field is different between the coils 105 and 107 and is not completely canceled out, so that it is difficult to suppress the measurement error.

  Further, in the above current measurement, in order to increase the measurement sensitivity, it is necessary to increase the induced voltage contributing to the measurement of both the coils 105 and 107. In each of the coils 105 and 107, each cross section of the cross-sectional area surrounded by the conductor portion It is desirable to generate the induced voltage uniformly with the same area. However, the cross-sectional areas of both the coils 105 and 107 are different for each winding pitch, and therefore there is a problem that the measurement sensitivity is deteriorated.

In addition, as an alternating current detection coil, a coil main body is arranged around the opening of the substrate on an insulating substrate, and has a winding coil and a winding coil formed in a coil shape with a conductive film, and these are connected in series. An air-core coil is known (see Patent Document 2). However, in this air-core coil, when viewed from the axial direction of the coil, the winding advance coil forms a sawtooth pattern, and the rewinding coil has a triangular shape, and the two coils have different shapes. Yes. For this reason, since the area surrounded by both coils is not the same, there is a difference in the amount of magnetic flux of the external magnetic field passing through both coils, and there is a problem that the influence of the external magnetic field cannot be sufficiently eliminated as described above. .
Japanese Patent Laid-Open No. 06-176947 Japanese Patent Laid-Open No. 2004-87619

  The present invention has been made in order to solve the above-described problem. By forming the radial lines and the connecting portions in the same shape on the front and back of the insulating substrate, the winding advance coil and the rewinding coil are formed on the insulating substrate. The purpose is to provide an AC current detection coil with low measurement error and good measurement sensitivity, with the same frontal area, canceling the effect of an external magnetic field that does not require detection between the winding and rewinding coils to suppress the effect And

In order to achieve the above object, according to the first aspect of the present invention, an opening is formed in an insulating substrate, a plurality of radial lines radially formed on both front and back surfaces around the opening, and a radial line on the front and back of the substrate. and a through hole for electrically connecting an electrical connection between the through hole and the end portion of the front and back surfaces of the radial line of the substrate to extend in the circumferential direction are merely an end side of the radial line It has a connecting portion, wherein the through hole comprises a belt Roidarukoiru connecting an end or connecting portion of the radial line at the end and the back-side of the connection or the radial-line conductor on the surface side, the toroidal Coils are formed on the front and back of the substrate in a winding direction and a rewinding direction, respectively, and these winding direction coils (referred to as advance coils) and rewind direction coils (referred to as return coils), In alternating current detection coil which is continuously connected in series, the connection portion, the connection portion is formed routed to avoid radial line adjacent radially lines connected, the radial line and the connection portion and the The front and back surfaces of the insulating substrate are formed in the same shape, and the areas of the lead coil and return coil patterns per coil are made equal.

According to a second aspect of the invention, the alternating current detection coil according to claim 1, the through-holes are arranged at equal intervals on a circumference around the substantial center of the opening, the flow proceeds before Symbol winding and winding The pitch of one turn of both return coils is equal.

According to a third aspect of the present invention, in the AC current detection coil according to the first or second aspect, the connection portion is provided on the outer peripheral side of the radial line.

According to a fourth aspect of the present invention, in the alternating current detection coil according to the first or second aspect, radial lines on the front and back sides of the insulating substrate are arranged at positions overlapping the front and back sides.

According to the present invention, the surface product as viewed from the take forward coil and unwinding the thickness direction of the insulating substrate of the coil are equal, that offset the induced electromotive current generated by the external magnetic field, to suppress a measurement error Therefore, the measurement accuracy of alternating current measurement is improved.

According to the invention of claim 2, it becomes easy to generate an induced current evenly one, easily achieving an improvement in measuring Jokan degree.

According to the invention of claim 3, becomes wider between radial lines on the outer peripheral side of the radial line, the ability to more arranged connecting section, it is possible to increase the radial lines, improving the wiring density of the coil Measurement sensitivity can be increased.

According to the invention of claim 4, it becomes easy to accurately cancel the effect of the external magnetic field, easily achieving an improvement in measurement accuracy of the ac current measurement.

  Hereinafter, an alternating current detection coil according to a first embodiment of the present invention will be described with reference to FIGS. 1 to 3. 1 and 2, an alternating current detection coil 1 (hereinafter referred to as a detection coil) of this embodiment is formed in a disc-shaped insulating substrate 2 serving as an air core of the coil, and in the center of the insulating substrate 2. And a toroidal coil 4 formed between the outer periphery of the insulating substrate 2 and the opening 3. The toroidal coil 4 includes a winding coil 5 in the winding direction and a rewinding coil 6 in the rewind direction, which are formed in duplicate on the same insulating substrate 2 and continuously connected in series. These coils 5 and 6 are provided at equal pitch intervals on a plurality of radial lines 7 formed radially from the openings 3 on both front and back surfaces of the insulating substrate 2 and on the outer periphery connecting the plurality of radial lines 7. The connecting portion 8 is formed by a through hole 9 that electrically continuously connects the radial lines 7 on the front and back sides and the connecting portion 8. In FIG. 1 and FIG. 2, these radial lines 7 and connecting portions 8 are indicated by solid lines on the front surface side of the insulating substrate 2 and indicated by broken lines on the back surface side. The same number of through-holes 9a and through-holes 9b are arranged at equal intervals on the circumferences on the side close to and far from the opening 3 with the approximate center of the opening 3 as the center.

  The radial lines 7 are arranged on the insulating substrate 2 at a constant pitch radially about the center axis 10 of the opening 3. The conductor part which comprises the radial line 7 and the connection part 8 is formed in the insulating board | substrate 2 with copper foil, and this copper foil can be formed by etching the double-sided printed circuit board which consists of epoxy resin containing glass, for example. it can. The connection portion 8 extends in the circumferential direction from an outer peripheral end portion (here, the through hole 9a) of the radial line 7, and electrically connects the plurality of radial lines 7. Then, the end portions and connection portions 8 of the plurality of radial lines 7 formed on the front and back surfaces of the insulating substrate 2 through the through holes 9 and the end portions and connection portions 8 of the radial lines 7 on the opposite surface. Are electrically connected in series to form a coil for winding the insulating substrate 2 around the conductor portion.

  The winding advance coil 5 forms a one-turn coil by electrically connecting the radial line 7 and the connecting portion 8 on the front side and the radial line 7 on the back side through the through holes 9. Similarly, the rewinding coil 6 forms a one-turn coil by electrically connecting the radial line 7 on the front side and the radial line 7 and the connecting portion 8 on the back side through the through holes 9. The pitches of the coils of the winding and rewinding coils 5 and 6 are equal. The connecting portion 8 is formed so as to avoid the adjacent radial line 7, and the coil pattern formed by the connecting portion 8 and the radial line 7 of both the coils 5 and 6 is formed in the same shape on the front and back of the insulating substrate 2. Has been. With the above configuration, the conductor portion (conductor film) forming the coil of the toroidal coil 4 is formed substantially symmetrically and uniformly with respect to the central axis 10 of the opening 3 of the insulating substrate 2.

  With reference to FIG. 2, the details of the connection between the winding advance coil 5 and the rewinding coil 6 will be described. The winding advance coil 5 starts from the first radial line 71 connected from the coil lead-out terminal 11a, passes through the inner peripheral side through hole 9b, the back side radial line 72, the outer peripheral side through hole 9a, and the front side connection portion 8, It is connected to the next radial line 73, and thereafter, in the same manner, it winds about once in the counterclockwise direction, and ends with the radial line 75 on the back side through the inner radial side through hole 9 b through the last radial line 74. Thereafter, the rewinding coil 6 is started through a continuous folding line 76 (connection point) continuous to the line 75. The rewind line 6 is starred from the first radial line 77 through the through hole 9a on the outer periphery side to which the folding line 76 is connected, and is connected to the radial line 78 on the back surface through the through hole 9b. In the same manner, the wire advances about once in the clockwise direction, ends at the last radial line 79, and is connected to the coil lead-out terminal 11b through the through hole 9a that is the terminal.

  As described above, the winding advance coil 5 and the rewinding coil 6 are formed in the winding advance direction and the rewind direction so that the pitch of each coil is equal and the induced electromotive force is electrically in the same direction. It is wound. As a result, the induced current in the same direction is detected for the magnetic flux passing through the coil cross sections of both the coils 5 and 6, and the induction in the opposite directions is performed for the external magnetic field from the vertical direction of the insulating substrate 2. Detect current. That is, in the detection coil 1, in the entire toroidal coil 4, the detected current with respect to the magnetic field from the conductor to be measured is the sum of the induced currents generated in the coils 5 and 6, and the induced current proportional to the number of turns of all the coils. For the external magnetic field, the difference between the induced currents detected by the coils 5 and 6 is measured. The detected currents from both the coils 5 and 6 are output from the coil lead terminals 11a and 11b.

  Next, with reference to FIG. 3, it will be described that the influence of the external magnetic field is reduced by the winding advance coil 5 and the rewinding coil 6. FIG. A region surrounded by each one coil pattern of the winding advance coil 5 and the rewinding coil 6 when viewed in the thickness direction of the insulating substrate 2, that is, the axial direction is indicated by a region S1 and a region S2. The region S1 is a shaded region surrounded by the front-side radial line 7a, the back-side radial line 7b, and the front-side connection portion 8a. The region S2 is a region in which cross diagonal lines surrounded by the radial line 7c on the back surface of the rewinding coil 6, the radial line 7d on the front surface, and the connecting portion 8b on the back surface are given. Moreover, the part which gave the continuous line and the broken line alternately is area | region S3 common to each coil. In the detection coil 1 of the present embodiment, the radial line 7 and the connecting portion 8 are formed in the same shape on the front and back of the insulating substrate 2, so that the pattern of the winding advance coil 5 and the rewinding coil 6 is per one coil. The areas of are almost equal.

Therefore, if the winding number of the winding advance coil 5 and the rewinding coil 6 is 30 turns, for example,
The area of the region S1 × 30 turns = the area of the region S2 × 30 turns. For this reason, the induced electromotive forces generated in the winding coil 5 and the rewinding coil 6 due to the external electromagnetic field are equal and the induced electromotive forces are electrically opposite to each other. The induced electromotive force is offset. Thereby, the current measurement accuracy is improved and sensitivity is improved.

  In the alternating current detection coil 1 of the present embodiment, the conductor portion of the toroidal coil 4 can be formed substantially symmetrically and uniformly around the central axis 10 of the opening 3. Since the circumferential section of the rewinding coil 6 has the same shape and the same area, the magnetic flux smoothly flows in the continuous coil. Thereby, an induced current can be generated uniformly and measurement sensitivity is improved. Further, by forming an etching pattern and a through hole on a single double-sided printed board having an opening 3, it can be manufactured in a small size and easily, and the manufacturing cost can be reduced. In addition, a current measurement of several tens of mA or more can be performed with a coil shape of a printed circuit board of 1 mm or less, and miniaturization and high performance are possible.

  Next, a modification of the detection coil 1 of the first embodiment will be described with reference to FIGS. 4 (a) and 4 (b). In the detection coil 1 of this modification, the connection portion 8 is arranged on the inner peripheral side near the opening 3 of the insulating substrate 2 and the connection point 76 from the winding coil 5 to the rewinding coil 6 is the same. It is different from the above in that it is arranged on the inner peripheral side, and the other configurations are the same. The same members are given the same numbers (hereinafter the same). With such a configuration, in addition to the same effects as described above, the connection portion 8 is provided on the side close to the opening 3, so that the outer shape of the insulating substrate 2 can be reduced and the entire coil can be reduced in size.

  Next, another modification of the detection coil of the first embodiment will be described with reference to FIGS. In the above embodiment, the through holes that connect the front and back of the coil are arranged in order on the same circumference. However, in the modification shown here, the through holes are regularly arranged on the circumference of two concentric circles having different radii. Are arranged.

  As shown in FIG. 5A, in the arrangement in which the through holes 9m and 9n are arranged on the same circumference, the number of lands of the through holes arranged within the circumferential length is the size of the land diameter of the through holes. Therefore, the number of lands that can be placed is limited. For this reason, the number of turns of the coil is also limited. On the other hand, as shown in FIG. 5B, in the detection coil 1 of this modification, the through holes 9m are evenly arranged on the circumference 1a of the insulating substrate 2 and are concentric with the circumference 1a. The through holes 9n are evenly arranged on the circumference 1b, and the through holes 9m and 9n are arranged in a zigzag shape so as not to overlap each other. Thereby, the number of through-hole lands can be increased, and the number of turns of the coil can be increased, so that the current sensitivity can be increased. It is desirable to provide the circumference 1a and the circumference 1b in the vicinity of each other.

  Yet another modification is shown in FIG. In this modification, the through holes connecting the front and back of the coil are regularly arranged on the circumference of three concentric circles having different radii. That is, the through holes 9m are arranged on the circumference 1a of the outer circumference concentric with the opening 3 of the insulating substrate 2, and the circumference 1c having a circumference smaller than the circumference 1a and the circumference 1c larger than the circumference 1a. The through holes 9n are evenly arranged on the top. The through holes 9m and 9n are arranged in a zigzag pattern alternately so as not to overlap each other. In this way, by arranging the through holes 9m and 9n on the triple circumference, the number of lands of the through hole can be further increased, so that the number of turns of the coil can be further increased and the current sensitivity can be increased. It can be improved further.

  Next, an alternating current detection coil according to a second embodiment of the present invention will be described with reference to FIGS. The detection coil 1 of the present embodiment is different from the above-described embodiment in that the radial lines 7 on the front and back of the insulating substrate 2 are arranged at positions where they overlap each other.

  Each coil of the toroidal coil 4 of the detection coil 1 is formed by electrically connecting the connecting portions 8 disposed on the inner peripheral side close to the radial lines 7 and the openings 3 through the through holes 9. The front and back radial lines 7 formed on the insulating substrate 2 are formed symmetrically at positions overlapping each other when viewed from the thickness direction of the insulating substrate 2. The connecting portions 8 extend in the circumferential direction from the end portion (here, the through hole 9b) on the inner peripheral side of the radial line 7, and are provided at equal pitch intervals on the inner periphery. Electrical connection between them. The conductor portion of the toroidal coil 4 is formed substantially symmetrically and uniformly around the central axis 10 of the opening 3 of the insulating substrate 2. The radial lines 7 (71 to 79) and the connecting portions 8 are indicated by solid lines on the front surface side of the insulating substrate 2 and indicated by broken lines on the rear surface side, but are on the rear surface side overlapping the radial lines 7 on the front surface side. The radial line 7 does not appear.

  With such a configuration, when the winding advance coil 5 and the rewinding coil 6 are viewed from the axial direction, the area surrounded by the radial lines 7 that overlap the front and back of the coils 5 and 6 becomes almost zero. Therefore, the area of the patterns of the coils 5 and 6 viewed from the axial direction can be the same and minimized. As a result, the induced electromotive current due to the external magnetic field can be minimized and canceled. Therefore, the influence of the external magnetic field can be extremely reduced, and the accuracy of current measurement can be further improved.

  Next, a modified example of the detection coil 1 of the second embodiment will be described with reference to FIGS. In this modification, the connecting portion 8 is disposed on the outer peripheral side away from the opening 3 of the insulating substrate 2, and the connection point 76 from the winding advance coil 5 to the rewinding coil 6 is also disposed on the outer peripheral side. This is different from the above, and the other configurations are the same.

  Each coil of the toroidal coil 4 is formed by electrically connecting the connecting portion 8 disposed on the outer peripheral side away from the radial line 7 and the opening 3 through the through hole 9. The conductor portion of the toroidal coil 4 is formed substantially symmetrically and uniformly around the central axis 10 of the opening 3 of the insulating substrate 2.

  Thus, by providing the connection part 8 on the outer peripheral side of the insulating substrate 2 having a large arrangement area, more connection parts can be arranged and the radial lines 7 can be increased, so that the wiring density of the coil is improved. Measurement sensitivity can be increased.

  Next, another modification of the detection coil 1 of the second embodiment will be described with reference to FIGS. In this modification, a pattern having the same electrical potential is applied in an empty space where no coil pattern is applied, and this pattern is connected to the reference potential side of the coil output signal.

  The detection coil 1 has a metal pattern 12 that is electrically at the same potential while maintaining electrical insulation from the coil pattern in an empty space where the coil pattern is not formed by the radial line 7 and the connecting portion 8 on the insulating substrate 2. Except for the above, the configuration is the same as that of the second embodiment. Therefore, the detailed description of the detection coil 1 of this modification is omitted. The metal pattern 12 is provided on both sides or one side of the insulating substrate 2 so as to be as wide and electrically as possible in an empty space where no coil pattern is provided. The metal pattern 12 is connected to the reference potential (for example, ground potential) side of the coil output signal.

  As described above, by providing the metal pattern 12 having the reference potential in the empty space of the pattern of the insulating substrate 2, it is possible to reduce the influence of electrostatic noise between the electric wire through which the current to be measured is passed and the coil. This eliminates the need for conventional shield processing such as covering the coil with a metal shield or covering the coil laminate substrate with a shield foil as a countermeasure against electrostatic noise, eliminating the need to configure the shield foil as a separate part and reducing costs. Is possible.

  Next, an alternating current detection coil according to a third embodiment of the present invention will be described with reference to FIG. The detection coil 1 of this embodiment is different from that of the first embodiment in that the radial lines 7 of the insulating substrate 2 and the connecting portions 8A that connect the radial lines 7 are formed by straight lines.

  As for the detection coil 1, the toroidal coil 4 is rewound from the winding advance coil 5 by electrically connecting the connecting portion 8A disposed on the outer peripheral side far from the radial line 7 and the opening 3 through the through hole 9. A coil 6 is formed. Here, the connection portion 8A is formed by being routed by a rectangular straight line so as to avoid the adjacent radial lines 7 (71 to 79), and the coil pattern formed by the connection portion 8A and the radial line 7 is the opening 3 of the insulating substrate 2. Are substantially symmetrical and uniform around the central axis 10.

  In this way, by forming the connecting portion 8A with a straight line, the coil pattern formed by the connecting portion 8A and the radial line 7 is all formed with a straight line except for the land pattern for through holes. Therefore, the coil pattern is configured in the same shape accurately and accurately on the front and back of the insulating substrate 2. Thereby, the area seen from the axial direction of the winding advance coil 5 and the rewinding coil 6 can be made more equal, the certainty of cancellation of the influence of the external magnetic field is increased, and current detection with higher accuracy can be performed. In addition, the coil pattern design can be easily and accurately performed with a straight line configuration.

  Next, a signal output of the alternating current detection coil and an embodiment of the signal processing unit of the present invention will be described with reference to FIGS. As shown in FIG. 11, the coil lead terminals 11 a and 11 b of the detection coil 1 are connected to the signal processing unit 30 via the signal output line pattern unit 20. The signal processing unit 30 includes an integration circuit 31 for converting an induced voltage having a differential waveform output from the coil extraction terminals 11a and 11b of the detection coil 1 into a current waveform, and an amplification circuit for amplifying the output of the integration circuit 31. 32, and current measurement is performed by the output current 33 of the integration circuit 31. The connection line from the detection coil 1 to the input end of the signal processing unit 30 is generally affected by an external magnetic field, which may cause a measurement error in coil current detection. Therefore, a signal output line pattern unit 20 as shown in FIG. 12 is used as this connection line. The signal output line pattern portion 20 has a wiring pattern formed so as to alternately intersect on both the front and back sides of the double-sided printed circuit board 20a, and gives the output wiring a twisted structure.

  This wiring pattern includes a signal line 21 and a GND line 22. The signal line 21 and the GND line 22 are continuously connected to each other through the through hole 23 so as to cross each other a plurality of times on the front and back of the printed board 20a. Thus, the signal line 21 and the GND line 22 are patterned using the through holes 23 so as to alternately cross the front surface and the back surface, and are formed in a twisted structure. The signal lines 21 on the front surface side and the back surface side of the printed board 20a are indicated by solid lines and broken lines, respectively, and the GND line 22 is indicated by thick solid lines and thick broken lines. The signal input terminal 21a and the ground input terminal 22a are connected to the coil lead terminals 11a and 11b, and the signal output terminal 21b and the ground output terminal 22b are connected to the signal processing unit 30 in the next stage.

  Thus, since the two output lines of the signal line 21 and the GND line 22 are formed in a twisted (crossed) structure, the influence of the external magnetism can be canceled between the two lines even if the external magnetism is received. Therefore, the influence of the external magnetic field on the connection line from the coil lead terminals 11a and 11b to the signal processing unit 30 can be reduced, and the current measurement error can be reduced. Furthermore, if the number of twists is increased, the influence of the external magnetic field can be further reduced. Further, if the detection coil 1 provided with the signal output line pattern unit 20 and the signal processing unit 30 are integrated on the same printed circuit board, a small and compact current sensor can be realized.

  Next, another example of the signal output line pattern unit 20 is shown in FIG. The signal output line pattern portion 20 is formed so that the signal output line 21 and the ground output line 22 overlap on both the front and back surfaces when viewed from the thickness direction of the printed board 20a.

  That is, the signal line 21 and the GND line 22 are arranged such that the GND line 22 is arranged on the back side of the signal line 21 on the front side and the signal line 21 is arranged on the back side of the GND line 22 on the front side. The pattern wiring is overlapped. The front and back pattern wirings are connected by through holes. The signal lines 21 on the front surface side and the back surface side of the printed circuit board 20a are indicated by solid lines and broken lines. Similarly, the GND line 22 is indicated by thick solid lines and thick broken lines.

  By using the signal output line pattern unit 20 having such a configuration, an induced electromotive force generated between the signal line 21 and the GND line 22 patterned on the front side with respect to a magnetic field coming from an arbitrary direction, and the back side Since the induced electromotive forces generated between the signal line 21 and the GND line 22 cancel each other, the magnetic influence can be suppressed. Thereby, the influence by the external magnetic field in the connection line from the coil extraction terminals 11a and 11b to the signal processing unit 30 can be reduced. Further, since the number of through holes can be reduced, the influence of an external magnetic field can be eliminated by minimizing the number of through holes.

  According to the detection coil 1 according to the above-described various embodiments, a double-sided printed circuit board can be used to obtain a current detection coil with a high detection sensitivity that is less affected by an external magnetic field. A low-cost current sensor that is easy to mass-produce can be realized. In the various embodiments described above, the coil is formed using the printed circuit board. However, the coil is not limited to the printed circuit board as long as the coil is formed.

The top view of the coil for alternating current detection which concerns on the 1st Embodiment of this invention. The enlarged view of the A section of FIG. The figure which shows the area which the winding advance coil and rewinding coil of the said coil for a detection form. (A) is a top view of the modification of the said embodiment, (b) is an enlarged view of the B section of (a). (A) is a schematic diagram of the said embodiment for a comparison, (b) is a schematic diagram of the other modification of the said embodiment. The schematic diagram of the other modification of the said embodiment. (A) is a top view of the coil for alternating current detection which concerns on the 2nd Embodiment of this invention, (b) is an enlarged view of the C section of (a). (A) is a top view of the modification of the said embodiment, (b) is an enlarged view of the D section of (a). (A) is a top view of the other modification of the said embodiment, (b) is an enlarged view of the E section of (a). The top view of the coil for alternating current detection which concerns on the 3rd Embodiment of this invention. The block diagram for the electric current detection by the coil for an alternating current detection of this invention. The block diagram of the signal output line pattern part of the said coil for an alternating current detection. The block diagram of the modification of the said signal output line pattern part. The front view of the conventional coil for alternating current detection. The elements on larger scale of the said coil for a detection.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Coil for alternating current detection 2 Insulation board | substrate 3 Opening 4 Toroidal coil 5 Winding advance coil 6 Rewinding coil 7, 7a, 7b, 7c, 7d Radial line 8, 8a, 8b, 8A Connection part 9, 9a, 9b, 9m , 9n through hole 71-79 radial line

Claims (4)

A plurality of radial lines formed radially on the front and back surfaces around the opening , through holes for electrically connecting the radial lines on the front and back sides of the substrate , and the radial lines one a-end side extends in the circumferential direction has a connecting portion for electrically connecting between the through hole and the end portion of the front and back surfaces of the radial line of the substrate, wherein the through hole surface of the with a connection portion or belt Roidarukoiru connecting an end or connecting portion of the radial line at the end and the back side of the radial line in a direction unwinding the winding proceeds direction the toroidal coils on the front and back of the substrate And a coil for detecting an alternating current in which the winding direction coil (referred to as a leading coil) and the rewinding direction coil (referred to as a return coil) are continuously connected in series. In,
The connecting part is formed so as to avoid a radial line adjacent to the radial line to which the connecting part is connected , and the radial line and the connecting part are formed in the same shape on the front and back of the insulating substrate, An alternating current detecting coil characterized in that the areas of the lead coil and return coil patterns are equal to each other.   2. The through-holes are arranged at equal intervals on a circumference centered on a substantially center of the opening, and the pitches of one turn of the winding advance and rewind coils are equal. The coil for alternating current detection as described in 2.   The alternating current detection coil according to claim 1, wherein the connection portion is provided on an outer peripheral side of the radial line.   The alternating current detection coil according to claim 1 or 2, wherein radial lines on the front and back sides of the insulating substrate are arranged at positions overlapping the front and back sides.

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