JP4512358B2 - Filter element - Google Patents

Description

  The present invention relates to a spiral laminated filter element, and more particularly to a technique for increasing the degree of freedom in how to draw out lead terminals connected to a signal transmission line and a ground line while maintaining desired performance. .

  A spiral laminated filter element is a filter in which a signal transmission line and a ground line, both of which are formed in a strip shape, are wound in a spiral shape with a tape-shaped insulator in between, and its main use is due to a switching regulator or the like. Although it is for power supply noise removal, operation as a transformer has also been confirmed.

  In the spiral laminated filter element, since the signal transmission line is sandwiched by the ground line via an insulator, both the signal transmission line and the ground line are magnetically coupled to each other, and have a large distributed inductance. Looking at the ground line, the end side opposite to the ground point has an inductive impedance in the path to the ground point due to the distributed inductance of the ground line itself. As a result, the ground potential is set to the ground potential (0 V) over the entire length of the ground line. Not necessarily.

  As described above, since the potential of the ground line existing on both sides of the signal transmission line is asymmetrical, the operation of the spiral laminated filter element is extremely complicated. However, as one of the factors that influence the performance and characteristics, lead The arrangement of terminals is mentioned.

  That is, when winding the signal transmission line and the ground line with an insulator in between, a signal input lead terminal and a signal output lead terminal are connected to both ends of the signal transmission line, and at one end of the ground line Although the ground lead terminal is connected, the position of these three lead terminals after the winding greatly influences the performance and characteristics of the filter.

  In order to obtain excellent attenuation characteristics over a wide band, it is required that the three lead terminals of the signal input lead terminal, the signal output lead terminal, and the ground lead terminal are arranged on the same straight line at a predetermined interval. However, it is extremely difficult to wind up the signal transmission line and the ground line so that the three lead terminals are aligned on the same straight line.

  Therefore, in the three-terminal noise filter of Patent Document 1, a strip-shaped conductor (signal transmission line) in which the first inner lead and the first outer lead for input / output are connected in the vicinity of both ends, and the outer side for grounding in the vicinity of the outer end. When the grounding strip conductor (grounding line) to which the lead is connected is wound through the insulator sheet, the first inner lead and the first outer lead are shifted by 1/4 turn, and the first outer The lead and the grounding outer lead are wound in a state where they are close to each other in the circuit arrangement and are shifted by approximately 1/2 turn. Then, the wound laminated body is flatly pressed from the direction orthogonal to the straight line connecting the outer leads, so that the three leads are aligned on a straight line at substantially equal intervals.

Japanese Patent No. 2826320

  However, according to the filter described in Patent Document 1, since the positions of the three leads are fixed, on the circuit board side on which the filter is mounted, the arrangement of through holes and peripheral components is designed according to the lead positions. You are subject to design constraints that you must do.

  The above filter acts as a normal mode noise filter when there is one signal transmission line, and acts as a common mode noise filter when there are two (or more) signal transmission lines. However, if the air core is used like the filter described in Patent Document 1, a high attenuation effect cannot be obtained particularly for low-frequency noise.

  Further, when the common mode noise filter is used at a switching frequency of about several tens kHz to several hundreds kHz such as a switching power supply, the magnetic coupling between the signal transmission lines is made of a magnetic material in order to obtain a sufficient noise suppression effect. It is necessary to strengthen each other.

  For that purpose, a pot-type magnetic core made of, for example, ferrite including a center core disposed at the center of the coil laminate may be used as the magnetic body. However, there is a problem in drawing out lead terminals from the magnetic core. It becomes.

  In other words, the lead holes and the like are formed in the magnetic core in accordance with the positions of the three lead terminals connected to the coil laminate, but there are not a few misalignments in the actual assembly process. Further, when ferrite is used as the magnetic material, the ferrite is brittle and not very workable, so the core may be damaged during the machining depending on the position where the hole is drilled.

  Accordingly, an object of the present invention is to provide noise attenuation characteristics in a spiral laminated filter element in which a signal transmission line and a ground line, both of which are formed in a strip shape, are wound in a spiral shape with a tape-shaped insulator interposed therebetween. In order to improve the magnetic core, the three lead terminals connected to the coil body can be pulled out of the magnetic core from a predetermined position according to the form of the magnetic core.

  In order to solve the above-described problem, the filter element according to claim 1 is configured such that a signal transmission line and a ground line, both of which are formed in a band shape, are sandwiched between them with a tape-shaped insulator interposed between them and the signal transmission line. A coil body that is spirally wound so that the ground line is on the outside, and a magnetic circuit that includes a center core that is inserted through the center of the coil body and that interlinks with the coil body, A magnetic core having at least two lead extraction portions of first and second provided at different positions, and connecting a signal input lead terminal to the outermost peripheral portion of the portion functioning as a filter of the signal transmission line; A signal output lead terminal is connected to the innermost periphery of the portion that functions as a filter of the signal transmission line, and the ground line adjacent to the inner side of the outermost periphery of the signal transmission line is connected to the signal input. The lead terminal connection point is further extended within a range within one round of the outer periphery, the ground lead terminal is connected to a predetermined position of the extended portion, the signal input lead terminal is pulled out from the first lead lead portion, The ground lead terminal is pulled out from the second lead lead portion.

  Similarly, in order to solve the above-described problem, the filter element according to claim 2 is configured such that a signal transmission line and a ground line, both of which are formed in a band shape, are sandwiched between them with a tape-like insulator interposed therebetween. A coil body wound in a spiral shape with the signal transmission line on the outside and a center core inserted through the center of the coil body to form a magnetic circuit interlinking with the coil body. And a magnetic core having at least two lead lead portions provided at different positions, and a signal input lead terminal connected to the innermost peripheral portion of the portion functioning as a filter of the signal transmission line. In addition, a signal output lead terminal is connected to the outermost peripheral portion of the portion functioning as a filter of the signal transmission line, and the ground line adjacent to the outside of the innermost peripheral portion of the signal transmission line is The signal input lead terminal is further extended within the inner circumference within one round starting from the connection point of the signal input lead terminal, and the ground lead terminal is connected to a predetermined position of the extended portion, and the signal input lead terminal is connected to the first lead lead-out portion. Pulling out, the ground lead terminal is pulled out from the second lead lead portion.

  According to a third aspect of the present invention, when the signal input lead terminal is routed toward the first lead lead portion in the magnetic circuit, the direction of the lead is set to the winding direction of the coil body. Is also one of the features of the present invention.

  In this case, as described in claim 4, it is preferable that the lead length of the signal input lead terminal in the magnetic circuit is less than 360 ° starting from the connection point.

  In the present invention, as described in claim 5, the signal output lead terminal is pulled out from either the first lead lead portion, the second lead lead portion or a third lead lead portion different from these. It may be.

  According to a sixth aspect of the present invention, the magnetic core is a cylindrical pot-type core including the center core, and the first lead extraction portion and the second lead extraction portion are the above-described ones in the pot-type core. It is characterized in that the two paths passing through both sides of the center core are arranged at positions where the magnetic characteristics are substantially the same.

  According to a seventh aspect of the present invention, the magnetic core comprises a Japanese-shaped segment core including the center core, and the first lead lead portion and the second lead lead portion are linked to the coil body. The magnetic circuit is divided and arranged on both sides of the Japanese character segment core.

  The filter element of the present invention includes a normal mode noise filter having one signal transmission line according to claim 8 and one or more ground lines, and the signal according to claim 9. A common mode noise filter including a plurality of transmission lines and one or more of the ground lines is included.

  According to the present invention, the ground lead terminal can be connected to an arbitrary position of almost one turn on the outermost periphery of the ground line without impairing the performance and characteristics of the filter element. In the item 2, the ground lead terminal can be connected to an arbitrary position of almost one turn on the innermost circumference of the ground line. Furthermore, the signal input lead terminal can be routed in the same direction as the winding direction of the coil body in the magnetic circuit. Further, the signal output lead terminal can be arbitrarily pulled out from either the first lead drawing portion or the second lead drawing portion or a third lead drawing portion different from these. Therefore, the degree of freedom in how to draw out the lead terminals from the magnetic core is greatly increased.

  Further, as the magnetic core, the cylindrical pot-type core according to claim 6, wherein the first lead extraction portion and the second lead extraction portion have two paths of magnetism passing through both sides of the center core in the pot-type core. A magnetic core which is arranged at a position where characteristics are substantially the same, or a Japanese-shaped segment core according to claim 7, wherein the first lead extraction portion and the second lead extraction portion are linked to the coil body. By adopting a magnetic core that is divided and arranged on both sides of a Japanese character segment core by a circuit, a filter element having excellent noise attenuation characteristics is provided.

  Next, the present invention will be described with reference to some embodiments shown in the drawings, but the present invention is not limited thereto.

  FIG. 1 is an exploded perspective view of a filter element 1 according to an embodiment of the present invention, and FIG. The filter element 1 includes a coil body 10 and a magnetic core 20 in which the coil body 10 is housed as basic components.

  FIG. 3 shows a schematic exploded perspective view of the coil body 10. According to this, the coil body 10 includes a signal transmission line 110 formed in a band shape, a ground line 120 formed in the same band shape, and a pair of tape-shaped insulators 131 and 132. The signal transmission line 110 and the ground line 120 are made of a conductive material such as copper foil or aluminum foil, and the tape-like insulators 131 and 132 are dielectric insulators having good frequency characteristics, such as polyimide resin film and polyethylene. Is preferred.

  In addition, the signal transmission line 110 and the ground line 120 can be directly formed on the tape-shaped insulators 131 and 132 by, for example, vapor deposition or plating. As a matter of course, the widths of the tape-like insulators 131 and 132 are wider than the widths of the signal transmission line 110 and the ground line 120.

  Although the filter element 1 in this example is a normal mode noise filter and has one signal transmission line 110, a plurality of signal transmission lines 110 can be used as a common mode noise filter.

  A signal input lead terminal 111 and a signal output lead terminal 112 are connected to both ends of the signal transmission line 110. A ground lead terminal 121 is connected to one end side of the ground line 120. Although these connection locations will be described later, each of the lead terminals 111, 112, 121 may be in a pin shape, a wire shape, or a foil shape, and the wire diameter thereof may be arbitrarily selected. The connection means is generally welding, soldering, conductive adhesive, or the like, but in some cases, it can also be pulled out from the lead terminal.

  As an example, the coil body 10 is obtained by winding one tape-like insulator 132, the ground line 120, the other tape-like insulator 131, and the signal transmission line 110 in order and winding them in a spiral shape. Normally, each lead terminal is attached to the signal transmission line 110 and the ground line 120 before winding, but the lead terminal can be attached after winding.

  In this example, the magnetic core 20 is formed as a cylindrical pot-type magnetic core. The material is preferably ferrite. The pot-type magnetic core 20 is divided into an upper core 21 and a lower core 22, and on the upper core 21 side, there are two lead extraction portions (drawers) for pulling out lead terminals connected to the coil body 10 to the outside. Holes) 23 and 24 are formed.

  Center cores 21 a and 22 a that are inserted into the center of the coil body 10 are provided at the center of the upper core 21 and the lower core 22. The center cores 21a and 22a are provided with screw holes, and are fixed integrally by screwing male screws into the screw holes after assembly.

  In the present invention, when the coil body 10 is manufactured, the connection location of the signal input lead terminal 111 and the signal output lead terminal 112 is determined depending on whether the signal transmission line 110 is wound inside or outside the ground line 120. Change. This will be described with reference to FIG. 4, in which the tape insulators 131 and 132 are omitted.

  FIG. 4A shows a case where the signal transmission line 110 is wound on the inside and the ground line 120 on the other side. In this case, the signal input lead terminal 111 is placed on the outermost peripheral side of the signal transmission line 110. The signal output lead terminal 112 is connected to the innermost peripheral side of the signal transmission line 110.

  FIG. 4B shows a case where the signal transmission line 110 is wound outside and the ground line 120 is turned inside. In this case, the signal input lead terminal 111 is opposite to FIG. The signal output lead terminal 112 is connected to the innermost peripheral side of the signal transmission line 110, and the signal output lead terminal 112 is connected to the outermost peripheral side of the signal transmission line 110.

  Based on this premise, the connection location of the ground lead terminal 121 to the ground line 120 will be described with reference to FIG. First, with reference to FIG. 5 (a), the connection location of the ground lead terminal 121 when wound with the signal transmission line 110 inside and the ground line 120 outside as shown in FIG. 4 (a) will be described.

  In this case, as described above, the signal input lead terminal 111 is connected to the outermost peripheral side of the signal transmission line 110, but the ground line 120 adjacent to the inner side of the outermost peripheral part of the signal transmission line 110 is connected to the signal input lead 110. The terminal 111 is further extended within the range of one circumference or less from the connection point of the terminal 111, and the ground lead terminal 121 is connected to a predetermined position in the extended portion 120a.

  In the example of FIG. 5A, the grounding line 120 adjacent to the inside of the outermost periphery of the signal transmission line 110 is extended about a half circumference starting from the connection point of the signal input lead terminal 111, and the extension 120a A ground lead terminal 121 is connected to the tip.

  Next, with reference to FIG. 5 (b), description will be given of the connection location of the ground lead terminal 121 when wound with the signal transmission line 110 outside and the ground line 120 inside as shown in FIG. 4 (b). Add.

  In this case, as described above, the signal input lead terminal 111 is connected to the innermost peripheral side of the signal transmission line 110, but the signal is transmitted through the ground line 120 adjacent to the outside of the innermost peripheral part of the signal transmission line 110. The connecting portion of the input lead terminal 111 is further extended as long as it is within one round of the inner periphery, and the ground lead terminal 121 is connected to a predetermined position in the extended portion 120b.

  In the example of FIG. 5B, the ground line 120 adjacent to the outside of the innermost peripheral portion of the signal transmission line 110 is extended about a half circumference starting from the connection point of the signal input lead terminal 111, and the extended portion 120b A ground lead terminal 121 is connected to the tip of the terminal.

  Note that the connection portion of the signal input lead terminal 111 and the signal output lead 112 does not have to be a shape end of the signal transmission line 110. In short, the connection point between the signal input lead terminal 111 and the signal output lead 112 is a substantial end of the signal transmission line 110. In other words, the “outermost peripheral portion” and “innermost peripheral portion” of the signal transmission line 110 refer to both end portions of the portion functioning as a filter. The same applies to the ground lead terminal 121.

  Referring to FIG. 1 again, in the present invention, after the signal input lead terminal 111 and the ground lead terminal 121 are connected to the specific position described above, they are always pulled out of the magnetic core 20 separately from different lead lead portions. is important. For example, if the signal input lead terminal 111 is drawn from one lead lead portion 23, the ground lead terminal 121 is always drawn from the other lead lead portion 24.

  The signal output lead 112 is not limited in this way, and may be pulled out from the lead lead portion 24 together with the ground lead terminal 121, may be pulled out from the lead lead portion 23 together with the signal input lead terminal 111, and May be provided with another lead lead-out portion and lead out therefrom.

  As an example, when the coil body 10 is housed in the pot-type magnetic core 20 and the positions of the signal input lead terminal 111 and the lead lead-out portion 23 are shifted, the signal is used under the following conditions: The input lead terminal 111 can be routed in the magnetic core 20 toward the position of the lead extraction portion 23.

  The condition is that the signal input lead terminal 111 is routed in the same direction as the winding direction of the coil body 10 as shown in FIG. In the present invention, as shown in FIG. 7A, it is forbidden that the signal input lead terminal 111 is routed in the direction opposite to the winding direction of the coil body 10.

  In order to verify this, FIG. 6B shows a characteristic graph of the S parameter when the signal input lead terminal 111 is routed in the winding direction of the coil body 10 in accordance with the conditions of the present invention as shown in FIG. FIG. 7B shows a characteristic graph of the S parameter when the signal input lead terminal 111 is routed by a method contrary to the conditions of the present invention as shown in FIG. 7A. This graph clearly shows the difference in attenuation characteristics. The S parameter was measured in a 50Ω system using a network analyzer HP8751A manufactured by Agilent Technologies.

The example of FIG. 6 (a) but it is for FIG. 5 (a), is connected to the innermost end of the signal input lead terminal 111 is the signal transmission line 110 as shown in FIG. 5 (b) Can be routed under the above conditions.

  In the present invention, the routing length of the signal input lead terminal 111 in the magnetic circuit 20 is preferably less than 360 ° starting from the connection location. When the signal output lead terminal 112 and the ground lead terminal 121 are routed in the magnetic circuit 20, the signal output lead terminal 111 may be arbitrarily routed without being subjected to the conditions as in the signal input lead terminal 111.

  Next, the magnetic core provided in the filter element 1 of the present invention will be described. In addition to the pot-type magnetic core 20 shown in FIG. 1 and FIG. 2, the magnetic core includes a magnetic core (hereinafter referred to as a Japanese-shaped magnetic core) 30 composed of a Japanese-shaped segment core shown in FIG. It is.

  In the present invention, the magnetic cores 20 and 30 are provided with a magnetic circuit linked to the coil body 10 including a center core inserted through the center of the coil body 10 as a first requirement. As a second requirement, there are at least two independent lead extraction portions, and the two lead extraction portions are arranged at positions where the magnetic characteristics of two paths (wiring paths) passing through both sides of the center core are substantially the same. Two requirements are imposed.

  8 to 14 show examples 20a to 20g of pot-type magnetic cores 20 that can be employed in the present invention. 8 to 14 include a perspective view (upper stage) and a plan view (lower stage), respectively. Each of the magnetic cores 20a to 20g in each example includes the center cores 21a and 22a as shown in FIG. 1, but here, for convenience, a circle drawn at the center of each perspective view and its plan view is shown. Let the hole part be the center core C.

  The pot-type magnetic core 20a shown in FIG. 8 is the same as that shown in FIG. 1 and includes two independent lead lead portions 23 and 24. In this example, the lead lead-out portions 23 and 24 are round holes having the same diameter, and are arranged at point-symmetrical positions around the center core C. By doing so, for example, the path A from the first lead lead portion 23 to the other second lead lead portion 24 through the upper side (hereinafter simply referred to as the upper side) in the plan view of the center core C, and the second lead lead portion. In the plan view of the center core C from the portion 24, the magnetic properties of the path B passing through the lower side (hereinafter simply referred to as the lower side) toward the first lead extraction portion 23 can be made substantially the same. As described above, the signal input lead terminal 111 and the ground lead terminal 121 are always drawn from different lead lead portions.

  In the pot-type magnetic core 20b of FIG. 9, the first lead extraction portion 23 and the second lead extraction portion 24 of the pot-type magnetic core 20a are arranged on a diameter line passing through the center core C. The second lead extraction part 24 is arranged on the side opposite to the first lead extraction part 23 and on the inner peripheral side with the center core C interposed therebetween. Even in this case, the magnetic characteristics of the path A and the path B can be made substantially the same.

  The pot-type magnetic core 20c of FIG. 10 is an example in which the first lead extraction portion 23 and the second lead extraction portion 24 of the pot-type magnetic core 20a are both of the same shape and the same size. Further, the pot type magnetic core 20d of FIG. 11 has the first lead extraction part 23 on the upper surface side of the two lead extraction parts of the pot type magnetic core 20c of FIG. 10, and the second lead extraction part 24 on the bottom side. This is an example of arrangement. The first lead extraction portion 23 and the second lead extraction portion 24 may be round holes having the same diameter.

  The pot-type magnetic core 20e of FIG. 12 has, for example, round hole-shaped third and fourth lead extraction portions in addition to the elliptical first and second lead extraction portions 23 and 24 of the pot-type magnetic core 20c of FIG. In this example, 25 and 26 are added to provide four lead extraction portions. Similarly to the first and second lead lead portions 23 and 24, the third and fourth lead lead portions 25 and 26 are preferably arranged so that the magnetic characteristics of the paths A and B passing through them are substantially the same.

  The pot-type magnetic core 20f of FIG. 13 is an example in which the first lead extraction portion 23 and the second lead extraction portion 24 are formed as windows on the side surfaces of the core so that the magnetic characteristics of the paths A and B are substantially the same. It is. The pot-type magnetic core 20g of FIG. 14 has the same window-shaped third and fourth lead extraction portions 25 in addition to the window-shaped first and second lead extraction portions 23 and 24 of the pot-type magnetic core 20f of FIG. , 26 are added to the side surface of the core to provide four lead extraction portions. It is preferable that the third and fourth lead lead portions 25 and 26 are also arranged so that the magnetic characteristics of the paths A and B passing therethrough are substantially the same as the first and second lead lead portions 23 and 24. .

  In the case of having four lead lead portions as in the pot type magnetic cores 20e to 20g of FIGS. 12 to 14, the signal input lead terminal 111 and the ground lead terminal 121 have substantially the same magnetic characteristics in the paths A and B. The first and second lead lead-out portions 23 and 24 or the third and fourth lead lead-out portions 25 and 26 are separately drawn out from the set.

  If the wall thickness of the peripheral wall of the pot-type magnetic core is uniform, the first and second lead lead-out portions 23 and 24 (or the third and third leads) can be used to make the magnetic properties of the paths A and B substantially the same. 4 lead extraction portions 25 and 26) are arranged on a diameter line passing through the center core C. For example, when the thickness of the core peripheral wall on the path A side is different from the thickness of the core peripheral wall on the path B side, The first and second lead lead portions 23 and 24 are not necessarily arranged on a diameter line passing through the center core C.

  Next, the Japanese character magnetic core 30 shown in FIG. 15 will be described. FIG. 15A is a perspective view of the magnetic core 30, and FIG. 15B is a schematic plan view showing a state where the coil body 10 is attached to the magnetic core 30.

  The magnetic core 30 is connected to a center core 31 inserted through the center of the coil body 10 and an upper end and a lower end of the center core 31 so as to be arranged in parallel to each other along the diameter line of the coil body 10. A pair of upper and lower upper and lower yokes 32 and 33 and a pair of left and right side yokes 34 and 35 connected between both ends of the upper and lower yokes 32 and 33 are provided.

  The magnetic core 30 provides two magnetic circuits for the coil body 10. One is the first magnetic circuit including the center core 31, the left side portion of the upper yoke 32, the left side yoke 34, and the left side portion of the lower yoke 33, and the other is the right side portion of the center core 31, the upper yoke 32, and the right side. This is a second magnetic circuit including right side portions of the side yoke 35 and the lower yoke 33.

  In the magnetic core 30, both side surfaces of the magnetic core 30 are spatially divided by the magnetic circuit including the first and second magnetic circuits, so that one of the side surfaces (for example, the left side of FIG. 15B) ) Is defined as the first lead extraction portion 310, and the other side surface side (for example, the right side in FIG. 15B) is defined as the second lead extraction portion 320. That is, it can be said that the magnetic core 30 also includes two lead extraction portions 310 and 320 that are independent of the pot-type magnetic core 20.

  Assuming that the magnetic core 30 is symmetrical with respect to the center core 31, as shown in FIG. 16, the magnetic core 30 passes from one first lead extraction portion 310 to the other second lead extraction portion 320 through the upper side of the center core 31. The magnetic characteristics of the path A that reaches the first lead extraction part 310 from the second lead extraction part 320 side through the lower side of the center core 31 are almost the same.

  Therefore, this Japanese character-shaped magnetic core 30 also has the first and second requirements described above. When the signal input lead terminal 111 and the ground lead terminal 121 are pulled out, for example, as shown in FIG. If the signal input lead terminal 111 is drawn from the first lead lead portion 310 side, the ground lead terminal 121 is drawn from the second lead lead portion 320 side. Note that the signal output lead terminal 112 may be drawn from either the first lead lead portion 310 or the second lead lead portion 320.

  As a modification, as shown in FIG. 17A, in the case of a magnetic core 30a formed by crossing a Japanese character segment core in a cross shape with the center core 31 in common, the first lead extraction portion 310 and the second lead The lead lead-out portion 320 is divided into two parts, and there are four lead lead-out portions, ie, lead lead-out portions 310a and 310b and lead lead-out portions 320a and 320b.

  In the present invention, it is an essential requirement that the signal input lead terminal 111 and the ground lead terminal 121 are separately drawn out from two independent lead lead portions where the magnetic characteristics of the path A and the path B are substantially the same. .

  As shown in FIG. 17B, this requirement is met by a set of a lead lead-out portion 310a and a lead lead-out portion 320b opposed to each other by 180 ° around the center core 31 or a set of the lead lead-out portion 310b and the lead lead-out portion 320a. Either.

  Therefore, for example, if the signal input lead terminal 111 is drawn out from the lead lead-out portion 310a side, the ground lead terminal 121 is drawn out from the lead lead-out portion 320b facing the 180 °.

  Incidentally, as shown in FIG. 17C, the signal input lead terminal 111 is pulled out from the lead lead portion 310a (or the lead lead portion 310b), and the ground lead terminal 121 is lead lead portion 320a (or the lead lead portion 310a). Pulling out from the lead extraction part 320b) is a prohibited matter in the present invention because a lead extraction part having different magnetic characteristics across the core is used.

  The pot type magnetic core 20 is actually composed of a split core including an upper core 21 and a lower core 22 as illustrated in FIG. 1, and the Japanese character magnetic core 30 is actually a similar split core. Consists of. Therefore, an air gap of about 100 μm, for example, exists on the joining surface due to tolerance. In some cases, a larger air gap may be provided between the divided cores.

  When a magnetic circuit is not formed by this air gap, the two lead extraction portions (the lead extraction portion 310 and the lead extraction portion 320 in the case of the magnetic core 30) are connected to each other, and the present invention is not realized. Therefore, in the present invention, the air gap width allowed for the magnetic circuit is defined as follows.

  Referring to FIG. 18, for example, it is assumed that an air gap G having a width Lg exists in the side yokes 34 and 35 of the magnetic core 30. Here, assuming that the inner peripheral length of the magnetic circuit on one side included in the magnetic core 30 is Lin and the outer peripheral length is Lout, in the present invention, the width Lg of the air gap G is 1 / of the outer peripheral length Lout of the magnetic circuit. If it is less than 5, that is, Lg <Lout / 5, it is defined that a magnetic circuit linked to the coil body 10 is formed.

  In the above embodiment, a normal mode noise filter having one signal transmission line 110 and one ground line 120 is taken as an example, but in the case of a common mode noise filter, the number of signal transmission lines 110 is two or more. Also, there may be a plurality of ground lines 120.

  19 (a) shows a two-signal transmission line-2 ground line, FIG. 19 (b) shows a two-signal transmission line-4 ground line, FIG. 19 (c) shows a two-signal transmission line-partially coupled ground line, FIG. ) Shows each example of a two-signal transmission line-multi-division ground line.

  In this case, the signal input lead terminal 111 and the signal output lead terminal 112 are connected to each of the signal transmission lines 110. For the ground line 120, for example, the ground lead terminals 121 are grouped into predetermined groups. Is connected. For example, two signal input lead terminals 111 and two signal output lead terminals 112 may be connected to one signal transmission line 110, for example.

  When these lead terminals are pulled out of the magnetic core, the signal input lead terminals (one or group) 111 and the ground lead terminals (one or group) 121 that are electromagnetically coupled are picked up, and these lead terminals are picked up. As with the above-described embodiment, the magnetic characteristics are always drawn out of the magnetic core separately from the two independent lead extraction portions 23 and 24 (310, 320) having substantially the same magnetic characteristics. The signal output lead terminal (one or group) 112 is not particularly limited as in the above embodiment.

  As the magnetic core applied to the filter element of the present invention, in addition to the magnetic core described in FIGS. 8 to 17, an RM core shown in FIG. 20A, an EI core shown in FIG. The EER core shown in FIG. 10C, the EE core shown in FIG.

  According to the present invention, since the degree of freedom in how to draw out the lead terminals is high, productivity is improved, and a spiral laminated filter element having excellent attenuation characteristics over a wide band can be provided at low cost.

The disassembled perspective view which shows the filter element which concerns on one Embodiment of this invention. Sectional drawing of the said filter element. The expansion | deployment perspective view of the coil body with which the said filter element is provided. (A) (b) Both are typical top views which show the example of winding of the said coil body. (A) (b) is a schematic diagram explaining the connection location of the signal input lead terminal and ground lead terminal with respect to the said coil body. (A) The schematic diagram which shows the example of the routing of the signal input lead terminal by this invention in a magnetic core, (b) The graph which shows the attenuation characteristic at that time. (A) The schematic diagram which shows the example of routing of the signal input lead terminal different from this invention in a magnetic core, (b) The graph which shows the attenuation characteristic at that time. The perspective view and top view which show the 1st example of the pot type magnetic core with which the said filter element is provided. The perspective view and top view which show the 2nd example of the pot-type magnetic core with which the said filter element is provided. The perspective view and top view which show the 3rd example of the pot type magnetic core with which the said filter element is provided. The perspective view and top view which show the 4th example of the pot type magnetic core with which the said filter element is provided. The perspective view and top view which show the 5th example of the pot type magnetic core with which the said filter element is provided. The perspective view and top view which show the 6th example of the pot type magnetic core with which the said filter element is provided. The perspective view and top view which show the 7th example of the pot type magnetic core with which the said filter element is provided. (A) The perspective view which shows the Japanese character type magnetic core with which the said filter element is equipped, (b) The typical top view. The typical top view for demonstrating the magnetic characteristic of the said Japanese character type magnetic core. (A) The perspective view which shows the modification of the said Japanese character type magnetic core, (b) (c) The typical top view for demonstrating the magnetic characteristic. Explanatory drawing for demonstrating the definition of the magnetic circuit in this invention. (A)-(d) The schematic diagram which shows each example of the common mode noise filter to which this invention is applied. (A)-(d) The disassembled perspective view which shows another example of the magnetic core applied to the said filter element, respectively.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Filter element 10 Coil body 110 Signal transmission line 111 Signal input lead terminal 112 Signal output lead terminal 120 Ground line 120a, 120b Extension part 121 Ground lead terminal 131,132 Tape-shaped insulator 20 Pot type magnetic core 21a, 22a Center core 23 1st lead extraction part 24 2nd lead extraction part 30 Day-shaped magnetic core 31 Center core 310 1st lead extraction part 320 2nd lead extraction part

Claims (9)

A signal transmission line and a ground line, both of which are formed in a strip shape, are wound in a spiral shape with a tape-like insulator sandwiched between them so that the ground line is outside the signal transmission line. A magnetic circuit including a coil body and a center core inserted through the center of the coil body is formed and linked to the coil body, and at least two lead leads provided at different positions A magnetic core having a portion,
A signal input lead terminal is connected to the outermost peripheral portion of the portion functioning as a filter of the signal transmission line, and a signal output lead terminal is connected to an innermost peripheral portion of the portion functioning as a filter of the signal transmission line, and the signal The ground line adjacent to the inside of the outermost periphery of the transmission line is further extended within the outer circumference within one round starting from the connection point of the signal input lead terminal, and the ground lead terminal is connected to a predetermined position of the extended portion. And
The filter element, wherein the signal input lead terminal is pulled out from the first lead lead portion, and the ground lead terminal is pulled out from the second lead lead portion. A signal transmission line and a ground line, both of which are formed in a strip shape, are wound in a spiral shape with a tape-like insulator sandwiched between them so that the signal transmission line is outside the ground line. A magnetic circuit including a coil body and a center core inserted through the center of the coil body is formed and linked to the coil body, and at least two lead leads provided at different positions A magnetic core having a portion,
The signal input lead terminal is connected to the innermost peripheral portion of the portion that functions as a filter of the signal transmission line, and the signal output lead terminal is connected to the outermost peripheral portion of the portion that functions as a filter of the signal transmission line. The ground line adjacent to the outside of the innermost peripheral portion of the transmission line is further extended within a range of one inner periphery from the connection point of the signal input lead terminal, and the ground lead terminal is provided at a predetermined position of the extended portion. Connect
The filter element, wherein the signal input lead terminal is pulled out from the first lead lead portion, and the ground lead terminal is pulled out from the second lead lead portion.   3. The filter according to claim 1, wherein when the signal input lead terminal is routed toward the first lead lead portion in the magnetic circuit, the direction of the lead is a winding direction of the coil body. element.   4. The filter element according to claim 1, wherein the lead length of the signal input lead terminal in the magnetic circuit is less than 360 ° starting from the connection point. 5.   5. The signal output lead terminal according to claim 1, wherein the signal output lead terminal is led out from one of the first lead lead portion, the second lead lead portion, or a third lead lead portion different from these. The filter element according to item.   The magnetic core is a cylindrical pot-type core including the center core, and the first lead extraction portion and the second lead extraction portion are magnetized in two paths passing through both sides of the center core in the pot core. The filter element according to claim 1, wherein the filter element is disposed at a position where the characteristics are substantially the same.   The magnetic core includes a Japanese character segment core including the center core, and the first lead extraction portion and the second lead extraction portion are connected to the coil body by the magnetic circuit, and the Japanese character segment core. The filter element according to claim 1, wherein the filter element is arranged separately on both sides of the filter element.   8. The filter element according to claim 1, wherein the number of the signal transmission lines is one and the number of the ground lines is one or more, and the filter element functions as a normal mode noise filter. 9.   8. The filter element according to claim 1, wherein the filter element includes a plurality of signal transmission lines, and one or a plurality of the ground lines are provided to function as a common mode noise filter. 9.

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