JPH07106138A - EMC filter for multi-line balanced communication line - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide an EMC filter having an excellent ability to block a common mode noise current flowing through a multi-wire balanced communication line over a wide band [Structure] At least one first closed magnetic path structure Of the core arm and the second core arm having a length less than or equal to the length of the first core arm, and a flat closed magnetic circuit core, and a plurality of coils formed of at least one pair of wires. The paired wires are located close to each other and are wound around the closed magnetic circuit core so that the magnetic flux flows in the same direction in the closed magnetic circuit when current flows in the same direction in the paired wires of each coil. Has been done. Furthermore, these lines run in one direction from the signal input end of the coil to the signal output end.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an EMC (electromagnetic compatibility) filter for blocking a common mode noise current flowing in a balanced communication line transmission line composed of a large number of core wires over a wide band.

[0002]

2. Description of the Related Art In recent years,
With the spread of the ISDN system, for example, failure of communication equipment due to external electromagnetic interference that enters into equipment via multi-wire (unshielded) balanced communication line transmission path such as standard home bus, high-speed digital bus, interface cable and extension bus. And electromagnetic interference such as performance degradation is increasing. In order to reduce these electromagnetic interferences, and particularly to prevent interferences in communication equipments such as telephones and facsimile equipments that are often used in a non-grounded state, an EMC filter that simultaneously satisfies the following conditions is required. (1) A large attenuation effect in a non-grounded state with respect to various high frequency interference currents (common mode), (2) Small transmission loss with respect to an information signal (normal mode or differential mode), (3) Multi-line Small crosstalk between wire pairs.

As a conventional EMC filter for suppressing a common mode noise current flowing in the same direction in each core wire in a balanced communication line transmission line having a large number of core wires such as a multi-pair balanced cable and a flat cable, a conventional toroidal filter is used. A choke coil using a core or a through core is known.

58A and 58B are a perspective view and a cross-sectional view showing a schematic structure of a conventional choke coil filter using a toroidal core. In these figures, 580 is a ring-shaped toroidal filter. A core 581 is n coils wound around the toroidal core 580 and connected to n lines of a communication line transmission path (not shown), T ₁ , T ₂ ,
T ₃ , ..., T _n are input terminals of the coil, T ₁ ′, T ₂ ′,
_{T 3 ', ..., T n} ' denotes an output terminal of the coil, respectively. It is known that the common-mode noise current blocking capability of such a choke coil is determined by the self-inductance L of the coil, and the self-inductance L is proportional to the square of the number N of turns of the coil 581 wound around the core 580. . Therefore, the number of turns N is usually set to a value as large as possible.

However, as shown in FIG. 58B, since many coils 581 densely pass through the inner opening of the ring-shaped toroidal core 580, a stray capacitance Cs is inevitably applied between the input and output terminals of each winding. Occur.

59A and 59B are electrically equivalent circuits of the choke coil shown in FIG. (A) in the figure
, Cs is between the input and output terminals T ₁ −T ₁ ′, T ₂ −
_{T 2 ', T 3 -T 3} ', ..., stray capacitance of T _n -T _n ', Lc is the inductance (common mode inductance) with respect to the common mode current Ic, Re is the effective resistance of the coil. Further, in (B) of the figure, Cs is between the input and output terminals T ₁ −T ₁ ′, T ₂ −T ₂ ′, T ₃ −T ₃ ′, ...,
Stray capacitance of T _n -T _n ', Ld is the leakage inductance for the normal mode current an In, Rw is winding resistance of the coil. However, in these figures, mutual inductance between adjacent windings is omitted. In the multi-wire communication line, if the mutual inductance between the paired lines involved in signal transmission is M, then the above-mentioned common mode inductance Lc and leakage inductance Ld are Lc = L
+ M and Ld = L−M respectively.

When high-frequency common-mode current Ic flowing in the same phase in each line flows in from the input terminals T ₁ , T ₂ , T ₃ , ..., T _n of the choke coil filter of FIG. 58, the high-frequency components of these common-mode current Ic Passes through the stray capacitance Cs portion without passing through the winding and goes to the output terminal T ₁ ',
_{T 2 ', T 3',} ..., would reach the T _n '. Therefore, such a ring-shaped toroidal core 580 has a problem that the ability to block the high-frequency common-mode noise current Ic is low even when the inductance Lc of the coil is sufficiently large.

When the reciprocating signal current In (normal mode current) flowing through a pair of multi-wire communication lines is a current containing a high frequency component, for example, T ₁ -T between the input and output terminals shown in FIG. 59B. ₁ 'and T ₂ -T _2' such lines from consisting wire pair of,
The high frequency insertion loss in the pair of choke coil filters may become very large due to the presence of the above-mentioned leakage inductance Ld. Such an increase in insertion loss not only makes it difficult to transmit a signal through the paired line transmission line, but also may render a circuit connected to the paired line inoperable.

FIG. 60 is a perspective view showing a schematic structure of a conventional choke coil filter using a flat plate-like through core 600 that surrounds a flat line 601 of a multi-line balanced communication line such as a flat cable. It is a figure. In the choke coil filter having this type of structure, the stray capacitance between the windings and between the input and output terminals is smaller than that of the filter shown in FIG. However, since the line 601 of the communication line transmission path penetrates the flat loop core 600 only once (that is, the equivalent number of turns is 1 turn), the magnetic flux φ ₁ flowing in the core 600 based on the common mode noise current Ic, The inductance L generated by φ ₂ , φ ₃ , ..., φ _n has a considerably small value in the low frequency region.
Therefore, in order to prevent the common mode noise current Ic, it is necessary to greatly increase the cross-sectional area of the flat loop core 600 or to significantly increase the axial length l thereof. If the axial length l of the core 600 is short, the line 6
01 must pass through a large number of cores 600 one after another.

FIG. 61 is a perspective view showing a schematic structure of a conventional choke coil filter using a cylindrical through core 610 surrounding a line 611 of a multi-wire balanced communication line having a circular cross section such as a multi-pair balanced cable. It is a figure. The problem of the choke coil filter of this kind of structure is the same as that of the choke coil filter shown in FIG.

As described above, in the conventional choke coil filter using the ring-shaped toroidal core 580 shown in FIG. 58, the stray capacitance Cs has a low noise blocking capability against a high frequency common mode noise current, and the winding leakage inductance Ld causes There is a problem in that high frequency transmission loss increases and signal transmission is hindered. Further, the conventional choke coil filter using the flat plate-shaped through core 600 shown in FIG. 60 and the conventional choke coil filter using the cylindrical through core 610 shown in FIG. 61 have the common mode noise current Ic blocked in the low frequency region. Insufficient capacity, and in order to obtain sufficient blocking capacity, the cross-sectional area of the core is significantly increased, the axial length l of the core is significantly lengthened, or the axial length l is short. In this case, there is a problem that a large number of cores must be connected and used.

Therefore, it is an object of the present invention to provide an EMC filter for a multi-line balanced communication line, which has an excellent capability of blocking a common mode noise current flowing through the multi-line balanced communication line over a wide band.

A further object of the present invention is to provide an EMC filter for a multi-line balanced communication line, which has a small transmission loss for an information signal flowing through the multi-line balanced communication line and can be applied to a high-speed transmission line. .

Still another object of the present invention is to provide an EMC filter for a multi-line balanced communication line in which crosstalk between pairs of the multi-line balanced communication line is small.

[0015]

According to the present invention, an EMC filter for a multi-line balanced communication line has at least one first core arm constituting a closed magnetic circuit and a length equal to or less than a length of the first core arm. It has a flat-shaped closed magnetic circuit core having a second core arm having a length, and a plurality of coils formed of at least one pair of wires. The paired wires are located close to each other and are wound around the closed magnetic circuit core so that the magnetic flux flows in the same direction in the closed magnetic circuit when current flows in the same direction in the paired wires of each coil. Has been done. Furthermore, these lines run in one direction from the signal input end of the coil to the signal output end.

When a common mode noise current flows through the coil windings, the magnetic fluxes formed by the coils are added together in the closed magnetic circuit core, so that a very large inductance is obtained and the intrusion of noise is prevented. . When a signal current (normal mode or differential mode current) flows through the coil winding, the magnetic flux formed by each coil cancels each other out in the closed magnetic circuit core.
The leakage inductance is so small that the transmission of signals is not hindered.

According to the present invention, in particular, since a pair of wires for transmitting a signal are located close to each other and wound on the same closed magnetic circuit core, no leakage magnetic flux is generated. For this reason, the transmission loss for high-speed or high-frequency signal transmission is suppressed to a low level, and signal transmission in the high-frequency region becomes possible.

It is preferable that each pair of lines is constituted by a pair of parallel lines in close contact with each other.

It is also preferable that each pair of wires is composed of a pair of wires twisted together. By using the twisted wire, there is no imbalance between the paired wires, so that crosstalk with other paired wires can be suppressed to a very small level.

The first core arm is composed of a first section and a second section, and each pair of wires is wound in a distributed manner with a space between adjacent windings in the first section. Is preferred. By distributedly winding the paired wires around the core with a space between adjacent windings, the stray capacitance Cs between the windings of the paired wires can be reduced, and the common mode noise current can be obtained even in the high frequency region. It is possible to obtain a good blocking characteristic against.

It is preferable that each pair of wires is wound in a concentrated manner between adjacent windings in the second section without a space. By concentrating the paired wires in this manner, the number of turns can be increased to increase the self-inductance in the low frequency region, and as a result, good blocking characteristics against common mode noise current can be obtained even in the low frequency region. Obtainable. By providing both distributed and concentrated winding parts, the stray capacitance increases in the concentrated winding part, but since there is also a distributed winding part, the stray capacitance does not become so large as a whole, and Along with an increase in self-inductance due to the winding portion, it is possible to obtain an excellent noise suppressing ability in a wide band.

The wires forming each pair are wound in the first core arm in a distributed manner with a space between adjacent windings, and are concentrated in the second core arm without space between adjacent windings. It may be wound.

The EMC filter of the present invention is preferably
The signal input end is located at one end of the first core arm and the signal output end is located at the other end of the first core arm, and each wire starts from the signal input end and is wound around the first core arm. The lever is configured to advance in the axial direction of the first core arm and reach the signal output end.

The first core arm of the EMC filter of the present invention comprises at least an input side core arm and an output side core arm, the signal input end is located along the input side core arm, and the signal output end is along the output side core arm. Each wire starts from the signal input end and winds from the input side core arm to the output side core arm so that magnetic flux is generated in the same direction in the input side core arm and the output side core arm and arrives at the signal output end. It is also preferable that it is configured as follows.

The first core arm of the EMC filter of the present invention comprises at least an input side core arm and an output side core arm, the signal input end is located at the center of the input side core arm, and the signal output end is the output side core arm. Located at the center, each wire starts from the signal input end and is wound around the input side core arm and goes to one end of this input side core arm, and it is wound around the output side core arm and wound around the output side core arm. It is also preferable that it is configured so as to proceed to the central portion of and reach the signal output end.

The second section described above is located near the center of the first core arm and the first section is located on both sides of the second section, or the first section described above is the first section. It may be located near the center of one core arm and the second section may be on either side of the first section.

The closed magnetic circuit core may be composed of two parallel first core arms and two parallel second core arms which are connected to each other to form a rectangular loop core.

The closed magnetic circuit cores may be composed of two first core arms and two second core arms which are connected to each other to form a core of a substantially rhombic loop or an elliptic loop.

The auxiliary closed magnetic circuit core is bridged between the above-mentioned two first core arms in the second section thereof, and the pair of wires is common to the auxiliary closed magnetic circuit core in the second section of the first core arm. May also be wound.

The closed magnetic circuit core is composed of a center core arm and at least two side core arms connected to both ends of the center core arm, the first core arm is composed of the center core arm, and the second core arm is composed of the second core arm. It may be composed of a side core arm.

The closed magnetic circuit cores are connected to each other and are connected to both ends of the center core arm and the two side core arms parallel to the center core arm and the center core arm and the side core arm which form the cores of the two rectangular loops. Two
It may be composed of two parallel second core arms, and the first core arm may be composed of a center core arm.

In this case, the auxiliary closed magnetic circuit core passes through the second section of the center core arm and is bridged between the two side core arms, and the pair line is shared with the second section of the center core arm. It may also be wound around the auxiliary closed magnetic circuit core.

[0033]

The present invention will be described in detail with reference to the following examples.

FIG. 1 is a plan view schematically showing the configuration of the first embodiment of the EMC filter of the present invention, and FIG. 2 is an electrically equivalent circuit diagram of the EMC filter shown in FIG. However, the effective resistance of the coil is omitted in the equivalent circuit of FIG.

In FIG. 1, 10 is two parallel first core arms 10a and two parallel second core arms 10a.
It shows a flat closed magnetic circuit core composed of b and b. The first core arm 10a and the second core arm 10b are coupled to each other to form a (symmetrical) rectangular loop core. The first core arm 10a is the second core arm 10
It is longer than b, and the first and second core arms 10a and 10b form a closed magnetic path. The rectangular loop core 10 has an effective magnetic permeability μ equal to that of the conventional toroidal core 580 shown in FIG.

On the first core arm 10a, one or more pairs of wires 11 forming a plurality of coils, which are connected to respective wires of a multi-wire balanced communication wire (not shown), are wound. It should be noted that in FIG. 1 and the following figures, only one or several representative pairs are shown to facilitate understanding of the winding structure. In FIG. 1, the representative pair lines are indicated by W _i and W _j , for example.

Each of these pairs of lines 11 are arranged close to each other. Particularly in this embodiment, the lines forming each pair are parallel to each other and are in close contact with each other. Pair these lines 1
No. 1 is wound around the first core arm 10a in such a winding direction that magnetic flux flows in the same direction in the first core arm 10a when a common mode current flows. Half of the pair wires 11 are wound around one of the first core arms 10a, and the other half of the pair wires 11 are wound around the other first core arm 10a. These coils have a signal input end (input terminal) at one end of the first core arm 10a.
_{T 1, T 2, ...,} T i, T j, ..., T m, has a T _n, the signal output terminal to the other end of the first core arms 10a (output terminal) T ₁ ', T _2' , ..., T _i ', T _j ', ..., T _m ', T _n '
have. The pair wire 11 includes signal input ends T ₁ , T ₂ , ..., T _i , T _j , ..., T at one end of the first core arm 10 a.
_{One direction from m} , T _n toward the signal output ends T ₁ ′, T ₂ ′, ..., T _i ′, T _j ′, ..., T _m ′, T _n ′ at the other end of the first core arm 10 a. We are proceeding without returning to (ie one way only). That is, each pair of wires is configured to start from the signal input end, wind around the first core arm 10a, move in the axial direction thereof, and arrive at the signal output end.

Each of the first core arms 10a is divided into three sections along its axis. That is, as shown in FIG. 1, two first sections Sb and Sc and one second section
Is Sa. In the first sections Sb and Sc located on both sides of the second section Sa, the pair lines 11b and 11
c is wound (coarsely) with a space between adjacent windings and distributed. In the second section Sa located in the approximate center of the first core arm 10a, each pair of wires 11
A is wound (densely) in a concentrated manner with almost no space between adjacent windings. In FIG. 1, the stray capacitances between the input and output of these sections Sa, Sb, and Sc are represented by Cs _a , Cs _b, and Cs _c , respectively. In this way, the distributed winding sections Sb and Sc are equal to the concentrated winding section S.
Since it is sufficiently longer than a, the stray capacitance Cs _a per unit length is equal to the stray capacitance Cs _b and C per unit length.
The stray capacitance Cs as a whole, which is considered to be _{a combination} of these Cs _a , Cs _b, and Cs _c in series by the action of these small Cs _b and Cs _c even if they are larger than s _c
Increase is suppressed. As a result, even if the common mode noise current Ic is a high frequency current, the large inductance L effectively acts, and the intrusion of this noise current can be prevented.

In the above-described first embodiment, the second section (concentrated winding section) Sa is located substantially in the center of the first core arm 10a, but in the present invention, this second section Sa is Obviously, it may be provided at any position on the first core arm 10a.

FIG. 3 shows the entire winding section (Sa, Sb and Sc).
Concentrated winding section Sa for the axial length (half length) l ₀ of
Axial length of a graph showing the relation between (semimajor) l _a ratio l _a / l ₀ and the ratio Cs / Cs ₀ of the input and output between the stray capacitance Cs of the coil. However, Cs ₀ is _a stray capacitance when la = l ₀ . In this case, the space (coil pitch) h between adjacent windings in the distributed winding section Sb (Sc) is constant (for example, h = 0.5 mm). As is clear from the figure, the shorter the l _a , the smaller the input / output stray capacitance ratio Cs / Cs ₀ . For example,
If l _a / l ₀ is 0.2 or less, Cs / Cs ₀ is 1.
It will be suppressed to 2 or less.

4A to 4C are views for explaining the winding structure of each pair of wires wound around the core in the distributed winding section Sb (Sc) of FIG. As shown in (A) to (C) of the figure, the lines forming each pair are arranged in parallel and in close contact with each other.

In the structure shown in FIG. 4A, the wires of each pair which are arranged in close contact with each other are wound around the core 10a in a single layer winding. That is, by inserting a spacer or the like (not shown), the space h is opened between the adjacent windings and W
₁ , W ₂ , ..., W _n are wound around the core 10a in this order from one end to the other end along the core 10a (unidirectional winding) and are wound in a single layer. According to this single layer unidirectional winding structure, the stray capacitance Cs _b
And Cs _c can be prevented from increasing, and the leakage inductance between pairs can be reduced.

In the structure of FIG. 4B, the wires of each pair which are arranged in close contact with each other are wound around the core 10a in two layers. That is, the pair of wires are first wound around the core 10a by two turns in two layers as indicated by W ₁ and W ₂ , and then a space (not shown) is inserted to insert a space h between adjacent windings. Open and wind 2 layers for 2 turns by W ₃ and W ₄ . Similarly, until the end of the winding W _n-1 and W _n of the distributed winding section, sequentially toward the one end along the core 10a at the other end two layers in one direction winding is performed. According to this two-layer unidirectional winding structure, the increase of the stray capacitances Cs _b and Cs _c can be prevented to some extent, and the leakage inductance between the paired wires can be reduced.

In the structure of FIG. 4C, each pair of wires is wound around the core 10a in two layers and reciprocally (return winding). That is, the paired wires are formed by inserting a spacer or the like (not shown) in the lower layer so as to leave a space h between adjacent windings and W ₁ , W ₂ , ... Wound from one end to the other, then in the upper layer, ..., W
along the core 10a as shown by the _n-1, W _n are wound in the opposite direction towards the one end from the other end. However, according to this two-layer return winding structure, the increase of the stray capacitances Cs _b and Cs _c cannot be effectively suppressed.

FIG. 5 is an adjacency with respect to the axial length l _b of the distributed winding section (Sb) in the two-layer unidirectional winding structure of FIG. 4 (B) and the two-layer return winding structure of FIG. 4 (C). it is a diagram representing the relationship between the ratio Cs / Cs _st ratio h / l _b and the input-output stray capacitance Cs of the coil space h between the winding pair. However, Cs _st is the standard stray capacitance in the case of h / l _b = 0.2. As is clear from the figure, the unidirectional winding structure has a very excellent suppressing effect on the increase of the stray capacitance Cs as compared with the return winding structure, and this suppressing effect by the unidirectional winding structure is also present. Of the coil pitch h on the coil pitch h is quite small.

Therefore, by using the unidirectional winding structure, it is possible to prevent the stray capacitance Cs from increasing without providing a space between the windings of each pair of wires.

FIGS. 6A and 6B show paired lines W _i and W.
FIG. 3 is a plan view illustrating an operation of the EMC filter according to the embodiment of FIG. 1 with respect to a common mode noise current Ic flowing through _j and a signal current (normal mode current) In.

As shown in FIG. 6A, the common mode
The noise current Ic is the pair line W_i And W_jMagnetic flux φ
_ciAnd φ_cjFlows in the first core arm 10a. this
Magnetic flux φ_ciAnd φ_cjFlow in the same direction in the closed magnetic circuit 10.
Therefore, the magnetic flux in the closed magnetic circuit 10 increases because they strengthen each other.
To do. In fact, the pair W_i And W_j Flow through a coil other than
Due to the common mode noise current Ic
As a result, a fairly large inductor as a whole
It acts as a sensor L. It is clear from the equivalent circuit of FIG.
As described above, the input / output stray capacitance Cs of the coil is
Capacity Cs_a , Cs_b And Cs_c By the synthesis of
Determined. Therefore, the distributed winding sections Sb and Sc are concentrated windings.
If it is sufficiently longer than the section Sa, the floating capacitance Cs_b 
And Cs _c Is the stray capacitance Cs_a Smaller than
Therefore, the stray capacitance Cs increases as a whole.
Is suppressed. As a result, the common mode noise current Ic
Has a large inductance L even if
It is possible to prevent this noise current from entering.
Wear.

As shown in FIG. 6B, when the normal mode current In flows through the pair lines W _i and W _j , the magnetic fluxes φ _ni and φ _nj flow in the first core arm 10a. Since each pair of wires are parallel lines closely contacting each other and wound on the same magnetic path, the magnetic fluxes φ _ni and φ _nj have the same value and flow in the closed magnetic path 10 in the opposite directions. Cancel each other out. As a result, the normal mode current I
Since M≈L with respect to n, the leakage inductance Ld does not occur, and the insertion loss hardly occurs.

FIG. 7 is a diagram showing frequency characteristics of common mode attenuation and normal mode attenuation of the EMC filter shown in FIG. In the figure, the horizontal axis represents frequency (MH
z) and the vertical axis represent the common mode attenuation amount Ac (dB) and the normal mode attenuation amount An (dB), respectively.

In this figure, two types of common mode damping characteristics Acc and Acs and two types of normal mode damping characteristics Anc and Ans are shown. Acc and Anc
Is the characteristic when a pair of wires closely attached to each other is used for winding,
Acs and Ans respectively indicate the characteristics when a pair of wires spaced apart from each other is used for the winding. As is clear from the figure, the common mode attenuation characteristic Ac (A
cc, Acs) does not depend on the type of pair wire used. That is, it does not depend on whether the pair lines are closely attached to each other or spaced apart from each other. However, the normal mode attenuation characteristic An (Anc, An
s) shows different changes depending on the type of pair wire used. That is, when the closely-paired pair wires that do not cause leakage inductance are used, the normal mode attenuation amount An becomes extremely smaller than when the paired wires that are spaced apart from each other are used.

FIG. 8 is a plan view schematically showing the configuration of the second embodiment of the EMC filter of the present invention. In this embodiment, the structure of the closed magnetic circuit core 80 is exactly the same as the structure of the core 10 in the first embodiment of FIG. However, in this embodiment, each pair of wires 81 is composed of a pair of twisted wires. By using the twisted wire, there is no imbalance between the paired wires, so that crosstalk between the multi-wire balanced communication line and other paired wires can be suppressed to a very small level. Other configurations and operational effects of the winding structure and the like in this embodiment are similar to those of the first embodiment of FIG.

FIG. 9 is a plan view schematically showing the configuration of the third embodiment of the EMC filter of the present invention. In this embodiment, the structure of the closed magnetic circuit core 90 is exactly the same as the structure of the core 10 in the first embodiment of FIG. Further, the configuration of each pair line 91 itself is exactly the same as the configuration of the pair line 11 in the embodiment of FIG. However, in this example,
Each pair of wires 91 is wound around the core 90 with a winding structure different from that of the first embodiment. That is, the first core arm 90
Each a is divided into three sections along its axis. That is, one first section Sa and two second sections S
b and Sc. The first section Sa is the second section Sb
And Sc respectively. In the first section Sa located on the center side of the first core arm 90a,
Each pair of wires 91a is wound (roughly) in a distributed manner with a space between adjacent windings. First core arm 90
In the second sections Sb and Sc located on both sides of the first section Sa along a, the pair lines 91b and 91c are concentrated (densely) between adjacent windings with almost no space.
It is wound.

Since the distributed winding section Sa is sufficiently longer than the concentrated winding sections Sb and Sc, even if the stray capacitances Cs _b and Cs _c per unit length are larger than the stray capacitance Cs _a per unit length, this small Cs _a By the action, the increase of the stray capacitance Cs as a whole is suppressed. As a result, even if the common mode noise current Ic is a high frequency current, the large inductance L effectively acts, and the intrusion of this noise current can be prevented. Other configurations and operational effects of this embodiment are similar to those of the first embodiment of FIG.

FIG. 10 is a plan view schematically showing the configuration of the fourth embodiment of the EMC filter of the present invention. In this embodiment, the shape of the closed magnetic circuit core 100 and each pair of wires 101
The winding structure is different from that of the core 10 and the pair wire 11 in the first embodiment of FIG. That is, in this embodiment, the closed magnetic circuit core 100 is composed of a (symmetrical) substantially diamond-shaped loop core. The loop core is formed by connecting two first core arms 100a and two second core arms 100b shorter than the first core arms 100a to each other. Therefore, the distance between the two first core arms 100a is the largest in their central portions.

Each of the first core arms 100a is divided into three sections along its axis. That is, FIG.
As shown in FIG. 2, there are two first sections Sb and Sc and one second section Sa. In the first sections Sb and Sc located on both sides of the second section Sa, the pair wires 101b and 101c are wound (coarsely) with a space between adjacent windings. First core arm 10
In the second section Sa located substantially in the center of 0a, the paired wires 101a are wound (densely) in a multi-layered manner with no space between adjacent windings. Since a sufficient distance can be obtained between the first core arms in the central portion of the first core arm 100a, it is possible to wind the pair of wires in multiple turns in the second section Sa. Therefore, even when the core size is small, a large number of turns can be wound in multiple layers, and the inductance can be greatly increased. Other configurations and operational effects of this embodiment are similar to those of the first embodiment of FIG.

FIG. 11 is a plan view schematically showing the configuration of the fifth embodiment of the EMC filter of the present invention. In this embodiment, the closed magnetic circuit core 110 is composed of a (symmetrical) oval or elliptical loop core formed by connecting two first core arms 110a and two second core arms 110b to each other. Except for the point
The configuration and effects of the above are the same as those in the case of the fourth embodiment of FIG. Although the boundary between the first core arm 110a and the second core arm 110b is not clear, in the present specification, a portion substantially parallel to the major axis is the first core arm 1
10a, and the portion parallel to the short axis is the second core arm 11
0b.

FIG. 12 is a plan view schematically showing the configuration of the sixth embodiment of the EMC filter of the present invention. In this embodiment, the (symmetrical) rectangular loop closed magnetic circuit core 12 is
0 is a center core arm (first core arm) 120
c, two side core arms 120a parallel to the center core arm 120c, and the center core arm 12
0c and 2 attached to the end of the side core arm 120a
Two second core arms 120b, and each of these arms forms two closed magnetic paths. Center core arm 120c and side core arm 120
a is set to be longer than the second core arm 120b. As shown in FIG.
The pair wire 121 is wound in the same winding structure as the pair wire 11 in the first embodiment shown in FIG. That is, the center core arm 120c is divided along its axis into three sections, which are two first sections and one second section. In the first section located on both sides of the second section,
Each pair of wires 121b and 121c are wound (roughly) in a distributed manner with a space between adjacent windings. In the second section located approximately in the center of the center core arm 120c, the paired wires 121a are wound (densely) in a concentrated manner with almost no space between adjacent windings.
The concentrated winding section may be composed of a coil in which a pair of wires are wound in multiple turns. Other configurations and operational effects of this embodiment are similar to those of the first embodiment of FIG.

FIG. 13 is a plan view schematically showing the configuration of the seventh embodiment of the EMC filter of the present invention. In this embodiment, the closed magnetic circuit core 13 of the (symmetrical) diamond-shaped loop
0 is a diagonal center core arm (first core arm)
130 c and four side core arms (second core arms) 130 b coupled to the ends of the diagonal center core arm 130 c, and two closed magnetic paths are formed. The diagonal center core arm 130c is set to be longer than the side core arm 130b. As shown in FIG.
The pair line 1 similar to the pair line 101 in the fourth embodiment shown in FIG.
31 is wound. That is, the center core arm 13
0c is divided along its axis into three sections consisting of two first sections and one second section. In the first section located on both sides of the second section, each pair of lines 13
1b and 131c are (roughly) wound with a space between adjacent windings and distributed. In the second section located substantially in the center of the center core arm 130c, the paired wires 131a are wound in a concentrated (dense) multi-layer structure with no space between adjacent windings. Other configurations and effects of this embodiment are similar to those of the first and fourth embodiments of FIGS. 1 and 10.

FIG. 14 is a plan view schematically showing the structure of the eighth embodiment of the EMC filter of the present invention. In this embodiment, the closed magnetic circuit core 140 of the (asymmetrical) triangular loop (half of the rectangular loop) includes one side core arm (first core arm) 140a and two side cores shorter than the side core arm 140a. And an arm (second core arm) 140b. A pair wire 141 is wound around the side core arm 140a similarly to the pair wire 11 in the first embodiment shown in FIG. That is, the side core arm 140a is divided along its axis into three sections, which are two first sections and one second section. In the first section located on both sides of the second section, each pair of wires 141b and 141c are wound (coarsely) with a space between adjacent windings. In the second section located substantially in the center of the side core arm 140a, the paired wires 141a are wound (densely) in a concentrated manner with almost no space between adjacent windings. Except that the core 140 is asymmetrical, the other configurations and effects of this embodiment are similar to those of the first embodiment of FIG.

FIG. 15 is a plan view schematically showing the structure of the ninth embodiment of the EMC filter of the present invention. In this embodiment, the structure of the closed magnetic circuit core 150 is exactly the same as the structure of the core 140 in the eighth embodiment of FIG. However, in this embodiment, each pair 151 is composed of a pair of twisted wires. By using a stranded wire,
Since there is no imbalance between the pair lines, crosstalk between the multi-line balanced communication line and other pair lines can be suppressed to a very small level. The other constructions such as the winding structure and the working effects in this embodiment are the same as those in the eighth embodiment of FIG.

FIG. 16 shows a tenth embodiment of the EMC filter of the present invention.
It is a top view which shows the structure of the Example of this. In this embodiment, the structure of the closed magnetic circuit core 160 having two parallel first core arms 160a and two parallel second core arms 160b is exactly the same as that of the core 10 in the first embodiment of FIG. is there. Further, the configuration of each pair line 161 itself is exactly the same as the configuration of the pair line 11 in the embodiment of FIG. However, in this embodiment, each pair 1
61 is a core 16 having a winding structure different from that of the first embodiment.
It is wound to 0. That is, each pair wire 161a is wound (coarsely) with a space between adjacent windings over the entire length of each of the first core arms 160a (coarsely). Each pair 16
1b is wound (densely) in a multilayer structure with almost no space between adjacent windings.

Since a sufficient distance can be obtained between the second core arms 160b, it is possible to wind the pair of wires in multiple turns in multiple layers. Therefore, even when the core size is small, a large number of turns can be wound in multiple layers, and the inductance can be greatly increased. The distributed winding section (first core arm) is the concentrated winding section (part of the second core arm).
Since it is sufficiently longer, it is possible to suppress an increase in stray capacitance as a whole. As a result, even if the common mode noise current Ic is a high frequency current, a large inductance L
Effectively acts to prevent the noise current from entering. Other configurations and operational effects of this embodiment are similar to those of the first embodiment of FIG.

FIG. 17 shows the eleventh embodiment of the EMC filter of the present invention.
It is a top view which shows the structure of the Example of this. In this embodiment, the structure of the closed magnetic circuit core 170 having two parallel first core arms 170a and two parallel second core arms 170b is exactly the same as that of the core 10 in the first embodiment of FIG. is there. Further, the winding structure of each pair wire 171 in the distributed winding sections (171b and 171c) and the concentrated winding section (171a) of the first core arm 170a is completely the same as the winding structure of the pair wire 11 in the embodiment of FIG. Is the same. However, in this embodiment, the auxiliary closed magnetic circuit core 172 having a rectangular loop is bridged between the two first core arms 170a in the central portion (concentrated winding section), and the paired wire 171a of the concentrated winding section is provided. Is also wound around the auxiliary closed magnetic circuit core 172 in common with the first core arm 170a.

Despite the large stray capacitance in the common winding section, the increase of the stray capacitance as a whole is small, and the auxiliary core 172 has an appropriate magnetic permeability.
Since the common mode inductance in the low frequency range can be increased to the required value by using,
The deterioration of the high-frequency characteristic is small, and the blocking capability for the common mode noise current can be further broadened as a whole. Other configurations and operational effects of this embodiment are similar to those of the first embodiment of FIG.

FIG. 18 shows the twelfth embodiment of the EMC filter of the present invention.
It is a top view which shows the structure of the Example of this. In this embodiment, a closed magnetic circuit core 180 having two first core arms 180a and two second core arms 180b.
The configuration of is the same as the configuration of the core 100 in the fourth embodiment of FIG. Further, the first core arm 180
The winding structure of each pair wire 181 in the distributed winding section (181b and 181c) and the concentrated winding section (181a) of a is exactly the same as the winding structure of the pair wire 101 in the embodiment of FIG. However, in this embodiment, the auxiliary closed magnetic circuit core 182 having a rectangular loop is bridged between the two first core arms 180a at the central portion (concentrated winding section), and the paired wire 181a of the concentrated winding section is provided. Is also wound around the auxiliary closed magnetic circuit core 182 in common with the first core arm 180a.

Despite the large stray capacitance in the common winding section, the increase of the stray capacitance as a whole is small, and the auxiliary core 182 has an appropriate magnetic permeability.
Since the common mode inductance in the low frequency range can be increased to the required value by using,
The deterioration of the high-frequency characteristic is small, and the blocking capability for the common mode noise current can be further broadened as a whole. Other configurations and operational effects of this embodiment are similar to those of the fourth embodiment of FIG.

FIG. 19 shows a thirteenth embodiment of the EMC filter of the present invention.
It is a top view which shows the structure of the Example of this. In this embodiment, a center core arm 190c, two side core arms 190a and two second core arms 190 are provided.
The structure of the closed magnetic circuit core 190 having b is exactly the same as the structure of the core 120 in the sixth embodiment of FIG. Further, the distributed winding section (19
1b and 191c) and the winding structure of each pair wire 191 in the concentrated winding section (191a) is also the winding wire of the pair wire 121 in the embodiment of FIG. 12 except that the concentrated winding 191a is a multilayer structure in this embodiment. It is exactly the same as the line structure. However, in this embodiment, a rectangular loop auxiliary closed magnetic circuit core 192 having a center arm is laid between the two side core arms 190a through the central portion (concentrated winding section) of the center core arm 190c. , The paired wire 191a of the concentrated winding section is the center core arm 190.
It is also wound on the center arm of the auxiliary closed magnetic circuit core 192 in common with c.

Despite the large stray capacitance in the common winding section, the increase of the stray capacitance as a whole is small, and the auxiliary core 192 has an appropriate magnetic permeability.
Since the common mode inductance in the low frequency range can be increased to the required value by using,
The deterioration of the high-frequency characteristic is small, and the blocking capability for the common mode noise current can be further broadened as a whole. Other configurations and operational effects of this embodiment are similar to those of the sixth embodiment of FIG.

FIG. 20 shows a fourteenth embodiment of the EMC filter of the present invention.
It is a top view which shows the structure of the Example of this. In this embodiment, the structure of the closed magnetic circuit core 200 having the two parallel first core arms 200a and the two parallel second core arms 200b is exactly the same as that of the core 160 in the tenth embodiment of FIG. is there. Further, the first core arm 200a is distributedly wound (201a) and the second core arm 200a is
Also, the winding structure of each pair wire 201 (201b) concentratedly wound around the core arm 200b of FIG.
The winding structure is the same as that of 61. However, in this embodiment, the two auxiliary closed magnetic circuit cores 2 of the rectangular loop are
02 are hung between the two first core arms 200a at both ends thereof (concentrated winding section), and the pair wire 201b of the concentrated winding section is commonly used as the auxiliary closed magnetic circuit core 202 with the second core arm 200b. Each is also wound.

Despite the large stray capacitance in the common winding section, the increase of the stray capacitance as a whole is small, and the auxiliary core 202 has an appropriate magnetic permeability.
Since the common mode inductance in the low frequency range can be increased to the required value by using,
The deterioration of the high-frequency characteristic is small, and the blocking capability for the common mode noise current can be further broadened as a whole. Other configurations and operational effects of this embodiment are similar to those of the tenth embodiment of FIG.

FIG. 21 is a fifteenth embodiment of the EMC filter of the present invention.
22 is a perspective view schematically showing the configuration of the embodiment of FIG. 22, and FIG. 22 is an exploded perspective view showing a more specific form of the 15th embodiment.

In FIG. 21, reference numeral 210 designates a flat closed magnetic circuit core composed of two parallel _first core arms 210a ₁ and 210a ₂ and two parallel second core arms 210b. The first core arms 210a ₁ and 210a ₂ and the second core arm 210b are connected to each other to form a (symmetrical) rectangular loop core.
The first core arms 210a ₁ and 210a ₂ are set longer than the second core arms 210b.
The core arms 210a ₁ and 210a ₂ and the second core arm 210b form a closed magnetic circuit. The rectangular loop core 210 has an effective magnetic permeability μ equal to that of the conventional toroidal core 580 shown in FIG.

First core arms 210a ₁ and 210a
Reference numeral ₂ denotes one or more pairs of wires 211 forming a plurality of coils, each of which is connected to each wire of a multi-wire balanced communication wire (not shown).
Is wound. 21 and 22, and in the following figures, only one or several representative pair lines are shown to facilitate understanding of the winding structure. Figure 2
1 and FIG. 22, this representative pair line is, for example, W
_{Denoted by i} and W _j . Each pair (W _i and W _j )
Is a closed magnetic circuit core 210 when a common mode current flows.
One of the first core arms 210a ₁ and 210a ₂ is wound in a certain winding direction and the other is wound in the opposite winding direction so that the magnetic fluxes flow in the same direction.

These pairs of lines 211 are arranged close to each other. Particularly in this embodiment, the lines of each pair are parallel and are in close contact with each other. The coil composed of these pairs of wires is provided with one first core arm (input side core arm) 21.
0a ₁ outside the signal input terminals (input terminals) T ₁ , T ₂ ,
, T _i , T _j , ..., T _m , T _n, and has a signal output end (output terminal) T ₁ ′, T on the outer side opposite to the other first core arm (output side core arm) 210a _{2. 2} '...
It has T _i ′, T _j ′, ..., T _m ′, T _n ′. Pair 211
Is the signal input end T of the input side core arm 210a ₁ .
_From T ₁ , T ₂ , ..., T _i , T _j , ..., T _m , T _n , the signal output end T ₁ ′ at the output side core arm 210a ₂ is
T ₂ ', ..., T _i ', T _j ', ..., T _m ', T _n 'going in one direction (one way) without returning. That is, each pair of wires, eg, pair wires W _i and W _j, has a signal input terminal T _i and T _j.
Starting from the _first core arm 210a 1
Is wound (roughly) so as to extend in the axial direction of the coil and to be distributed with a space between adjacent windings, and the coil is wound to the output side core arm 210a ₂ and the output side core arm 21
0a ₂ is wound (coarsely) so as to travel in the second axial direction opposite to the first axial direction and to be distributed with a space between adjacent windings, and then to the signal output terminal T _i. 'And T _j '
Is configured to arrive at. In this way, the EM in which the closed magnetic circuit core is elongated in the lateral direction with respect to the input / output terminals.
When the C filter is used, it is possible to reduce the size of the connecting means even for a multi-wire communication line having a large number of lines without enlarging the housing such as the connecting means for accommodating the EMC filter.

As shown in FIG. 22, paired lines W _i and W _j.
Are wound in a winding direction in a winding section of _one coil bobbin 213a ₁ , and the other coil bobbin 213a ₁ is wound.
_It is wound in the _second winding section in the opposite winding direction.
One end of each coil bobbin to wound the wire pair W _i and W _j, the terminal 214a ₁ and attached to the separator plate 215a ₁ and 215a ₂ for forming these coil bobbins 213a ₁ and 213a ₂ respectively winding sections 214
a ₂ are electrically connected to each other. The other ends of the paired wires W _i and W _j wound around each coil bobbin have terminals 21 attached to the other separation plates 215b ₁ and 215b _2.
4b ₁ and 214b ₂ are electrically connected. The terminals 214b ₁ and 214b ₂ are electrically connected to each other. This allows both coil bobbins 2
The paired wires W _i and W _{j that} are sequentially wound around 13a ₁ and 213a ₂ are formed. Other pairs of wires are similarly wound around the coil bobbin. Thus, the coil bobbin 213a
After the coil is wound around ₁ and 213a ₂ , the divided first core arms 210a ₁ and 210a ₂ are inserted and fixed in the coil bobbins 213a ₁ and 213a ₂ .

23A and 23B show the common mode noise current Ic and the signal current (normal mode current) In flowing through the pair lines W _i and W _j , respectively.
FIG. 6 is a plan view for explaining the operation of the EMC filter according to the example of FIG. Although the pair lines are shown separated from each other in these figures, the pair lines W _i and W _j are parallel lines closely attached to each other.

As shown in FIG. 23A, when the common mode noise current Ic flows through the pair lines W _i and W _j , the magnetic fluxes φ _ci and φ _cj generate the first core arms 210a ₁ and 210.
It flows in a ₂ . These magnetic fluxes φ _ci and φ _cj are the closed magnetic circuit 21.
The magnetic fluxes in the closed magnetic circuit 210 increase because they flow in the same direction in 0 and strengthen each other. In practice, the common mode noise current I flowing through the coils other than the pair wires W _i and W _j
Since magnetic flux in the same direction is also generated by c, it acts as a considerably large inductance L as a whole. Figure 2
As can be seen from FIG. 1 and FIG.
Since the core arms 210a ₁ and 210a ₂ are distributed and separately wound, the stray capacitance between the input and output ends is suppressed from increasing as a whole. As a result, even if the common mode noise current Ic is a high frequency current, the large inductance L effectively acts, and the intrusion of this noise current can be prevented.

As shown in FIG. 23B, when the normal mode current In flows through the pair lines W _i and W _j , the magnetic flux φ _ni.
And φ _nj are the first core arms 210a ₁ and 210a ₂
Flowing in. Since each pair of wires are parallel lines that are in close contact with each other and are wound in the same magnetic path, these magnetic fluxes φ _ni and φ
_{Since nj} are equal to each other and flow in the closed magnetic path 210 in opposite directions, they cancel each other. As a result, M≈L with respect to the normal mode current In, the leakage inductance Ld does not occur, and the insertion loss hardly occurs. Other configurations and operational effects of this embodiment are similar to those of the first embodiment of FIG.

FIG. 24 is a sixteenth embodiment of the EMC filter of the present invention.
It is a perspective view which shows the structure of the Example of this. In this embodiment, the structure of the closed magnetic circuit core 240 is as shown in FIGS.
The structure is exactly the same as that of the core 210 in the second fifteenth embodiment. Furthermore, the configuration of each pair line 241 itself is exactly the same as the configuration of the pair line 211 in the fifteenth embodiment. However, in this embodiment, each pair wire 241 has a winding structure different from that in the fifteenth embodiment.
It is wound in 0a ₁ and 240a _2. That is, each of the first core arms 240a ₁ and 240a ₂ is divided into three sections along its axis. That is, there are two first sections Sb and Sc and one second section Sa. Each of the first sections Sb and Sc is equal to the second section Sa.
Is longer than. In the second section Sa located on the center side of each winding section of the first core arms 240a ₁ and 240a ₂ , each pair wire 241a is wound (densely) in a concentrated manner with almost no space between adjacent windings. Has been done. In the first sections Sb and Sc located on both sides of the second section Sa of each winding section along the first core arms 240a ₁ and 240a ₂ , the pair lines 241b and 241 are formed.
c is wound (coarsely) with a space between adjacent windings and distributed.

The distributed winding sections Sb and Sc are concentrated winding sections.
Since it is sufficiently longer than Sa, the floating capacitor per unit length
Cs_a Is the stray capacitance Cs per unit length_b as well as
Cs _c Even if it is larger, this small Cs_b And Cs_c Work of
Increase in stray capacitance Cs as a whole
Is suppressed. As a result, the common mode noise current Ic
Has a large inductance L even if
It is possible to prevent this noise current from entering.
Wear. Other configurations and effects of this embodiment are as follows.
This is similar to the case of the fifteenth embodiment of FIGS. 21 and 22.
It

FIG. 25 is a seventeenth embodiment of the EMC filter of the present invention.
It is a perspective view which shows the structure of the Example of this. In this embodiment, the structure of the closed magnetic circuit core 250 is the first in FIG.
The configuration is exactly the same as that of the core 240 in the sixth embodiment. However, in this embodiment, each pair 251 is 1
It consists of a pair of twisted wires. By using the twisted wire, there is no imbalance between the paired wires, so that crosstalk between the multi-wire balanced communication line and other paired wires can be suppressed to a very small level. Other constitutions and operational effects such as the winding structure in this embodiment are the same as those in the 16th embodiment of FIG.

FIG. 26 shows the eighteenth embodiment of the EMC filter of the present invention.
It is a perspective view which shows the structure of the Example of this. In this embodiment, a closed magnetic circuit core 2 of a (symmetrical) rectangular loop
60 is a center core arm (first core arm) 26
And 0a _2, this center core arm 260a ₂ 2 two side cores in parallel to the arm 260a ₁ and 260a ₃ (first core arms), coupled to an end portion of the center core arm 260a ₂ and the side core arms 260a ₁ and 260a ₃ And two second core arms 260b, and each of these arms forms two closed magnetic paths. The center core arm 260a ₂ and the side core arms 260a ₁ and 260a ₃ are set to be longer than the second core arm 260b. The side core arm 260a ₁ , the center core arm 260a ₂ and the side core arm 260a ₃ have
A pair wire 261 is wound in the same manner as the pair wire 211 in the fifteenth embodiment shown in FIG. That is, each pair of lines, for example pair W
_i and W _j are distributed from the signal input ends T _i and T _j to the input side core arm 260a ₁ in the direction of the first axial direction of the input side core arm 260a ₁ with a space between adjacent windings. (Coarsely), it is wound around the center core arm 260a ₂ and the center core arm 260a ₂
Winding toward the second axial direction opposite to the first axial direction and distributed (roughly) so as to have a space between adjacent windings, and the output side core core arm 260a ₃
To the output side core core arm 260a ₃
In the axial direction and is wound (coarsely) so as to be distributed with a space between adjacent windings, and then to reach the signal output terminals T _i 'and T _j '. There is.

27A and 27B explain the operation of the EMC filter according to the embodiment of FIG. 26 with respect to the common mode noise current Ic and the signal current (normal mode current) In flowing through the pair lines W _i and W _j . FIG. Although the pair lines are shown separated from each other in these figures, the pair lines W _i and W _j are parallel lines closely attached to each other.

As shown in FIG. 27A, when the common mode noise current Ic flows through the pair lines W _i and W _j , the magnetic fluxes φ _ci and φ _cj flow in the side core arm 260a ₁ and the magnetic flux φ _ci ' And φ _cj ′ inside the center core arm 260a ₂ , and the magnetic fluxes φ _ci ″ and φ _cj ″ inside the side core arm 260a.
Flows in ₃ respectively. These magnetic fluxes φ _ci , φ _cj ,
Since φ _ci ′, φ _cj ′, φ _ci ″, and φ _cj ″ flow in the respective loops of the closed magnetic circuit 260 in the same direction, they strengthen each other and the magnetic flux in the closed magnetic circuit 260 increases. In fact, the pair W
_Since magnetic fluxes in the same direction are generated by the common mode noise current Ic flowing through the coils other than _i and W _j , they act as a considerably large inductance L as a whole.
As is clear from FIG. 26, since each pair of wires is distributed around the _three core arms 260a ₁ , 260a ₂ and 260a ₃ and is wound separately, the stray capacitance between the input and output ends increases as a whole. It can be suppressed. As a result, even if the common mode noise current Ic is a high frequency current, the large inductance L effectively acts, and the intrusion of this noise current can be prevented.

As shown in FIG. 27B, when the normal mode current In flows through the pair lines W _i and W _j , the magnetic flux φ _ni.
And φ _nj in the side core arm 260a ₁ , magnetic fluxes φ _ni ′ and φ _nj ′ in the center core arm 260a ₂ , and magnetic fluxes φ _ni ″ and φ _nj ″ in the side core arm 26.
0a ₃ flows respectively. Since each pair of wires are parallel lines closely attached to each other and wound in the same magnetic path, these magnetic fluxes φ _ni and φ _nj , magnetic fluxes φ _ni 'and φ _nj ' and magnetic fluxes φ _{ni ``} and φ _nj '' Are equal to each other and flow in the closed magnetic circuit 260 in opposite directions, and thus cancel each other out. As a result, for the normal mode current In, M≈
As a result, the leakage inductance Ld does not occur and the insertion loss hardly occurs. Other configurations and operational effects of this embodiment are similar to those of the fifteenth embodiment of FIGS. 21 and 22.

FIG. 28 is a nineteenth embodiment of the EMC filter of the present invention.
It is a perspective view which shows the structure of the Example of this. In this embodiment, a closed magnetic circuit core 280 having a combination of rectangular loops (asymmetric) has a corner core arm (first core arm) 280a ₂ and two side core arms parallel to the corner core arm 280a _2. 28
0a ₁ and 280a ₃ (first core arm), corner core arm 280a ₂ and side core arm 280a
₁ and 280a ₃ and two second core arms 280b connected to the ends thereof, and each of these arms forms two closed magnetic paths. Side core arm 2
The angle between the plane including 80a ₁ and the corner core arm 280a ₂ and the plane including the corner core arm 280a ₂ and the side core arm 280a ₃ is a right angle (90 °) so that the cross section of these planes is L-shaped. ing. Corner core arm 280a ₂ and side core arm 280
a ₁ and 280a ₃ are set to be longer than the second core arm 280b. Side core arm 28
A pair wire 281 is wound around 0a ₁ , the corner core arm 280a ₂ and the side core arm 280a ₃ similarly to the pair wire 261 in the eighteenth embodiment shown in FIG. That is, each pair of wires, eg, pair wires W _i and W _j, starts from the signal input ends T _i and T _j and advances to the input side core core arm 280a ₁ in its first axial direction and is adjacent to the winding. It is wound (coarsely) so as to have a space between the wires and distributed (coarsely), and it extends over the corner core arm 280a ₂ .
The corner core arm 280a ₂ is wound (roughly) so as to travel in a second axial direction opposite to the first axial direction and to have a space between adjacent windings (roughly). over the side core arm 280a _3, (rough) so as not distributed have a space between the at its output side core arm 280a ₃ first travels toward the axial direction and adjacent windings are wound, Then the signal outputs T _i 'and T _j '
Is configured to arrive at. Other configurations and operational effects of this embodiment are similar to those of the eighteenth embodiment of FIG.

FIG. 29 shows a twenty-first embodiment of the EMC filter of the present invention.
It is a perspective view which shows the structure of the Example of this. In this embodiment, a closed magnetic circuit core 290 having a three-dimensional shape formed by combining rectangular loops (asymmetric) has three corner core arms (first core arms) 290a ₂ , 290a ₃ and 290a ₄ , and these corner core arms 290a ₂ ,
Two side core arms 290a ₁ and 290a ₅ parallel to 290a ₃ and 290a ₄ ( _first core arm)
And corner core arms 290a ₂ , 290a ₃ and 2
90a _{4 and} side core arms 290a ₁ and 290
two second core arms 290b coupled to the end of a ₅
And each of these arms forms four closed magnetic paths. A plane including the side core arms 290a ₁ and the corner core arms 290a ₂ and the corner core arms 290a ₂ and 290a ₃
The angle with the plane including is at a right angle (90 °). Corner core arm 290a ₂ and corner core arm 2
The angle between the plane including 90a ₃ and the plane including the corner core arms 290a ₃ and 290a ₄ is a right angle (90 °). Corner core arms 290a ₃ and 290a
Plane and the corner core arm 290a ₄ containing ₄ and the side core angle between the plane containing the arm 290a ₅ perpendicular (9
0 °). Therefore, the cross sections of these four planes are W-shaped. That is, the closed magnetic circuit core 2 of this embodiment
90 is a form in which two closed magnetic circuit cores 280 of the embodiment of FIG. 28 are coupled.

Side core arm 290a₁ , Corner
Aarm 290a₂ , Corner core arm 290a₃ ,
Corner core arm 290a_Four And side core arm 2
90a_Five 28 includes a pair line 28 of the nineteenth embodiment shown in FIG.
A pair wire 291 is wound in the same manner as 1. That is, each pair
Line, eg pair W_i And W_j Is the signal input terminal T_i And T
_j Starting from the input side core arm 290a₁ Niso
In the first axial direction of the
It is wound (coarsely) so that it has a pace and is distributed.
-Ner core arm 290a₂ Across the corner core
Arm 290a₂In the second axial direction, which is the opposite of the first axial direction
Proceed towards and leave a space between adjacent windings
Corner core arms that are wound (coarsely) to be distributed
290a₃To the corner core arm 290a₃ 
In the first axial direction and between adjacent windings.
It is wound (coarsely) so that it has a pace and is distributed.
-Ner core arm 290a_Four Across the corner core
Arm 290a_Four In the second axial direction, which is the opposite of the first axial direction
Proceed towards and leave a space between adjacent windings
It is wound (coarsely) so as to be distributed, and the output side core
290a_Five To the output side core arm 2
90a_Five In the first axial direction and adjacent windings
Winding (coarsely) so that there is a space between the wires
Signal output terminal T_i'And T_jTo arrive at '
It is configured. Other configurations and operations in this embodiment
The effect of use is similar to that of the nineteenth embodiment shown in FIG.
It

FIG. 30 shows the 21st part of the EMC filter of the present invention.
3 is a cross-sectional view schematically showing the configuration of the embodiment of FIG. This embodiment has the same structure and effects as the 20th embodiment of FIG. 29 except for the following points. That is, in the present embodiment, the angle θ between the plane including the side core arms 300a ₁ and the corner core arms 300a ₂ and the plane including the corner core arms 300a ₂ and 300a ₃ is smaller than the right angle. , Corner core arm 300a ₂ and corner core arm 30
Angle between the plane containing the plane and the corner core arm 300a ₃ and 300a ₄ containing 0a ₃ theta has become a smaller angle than a right angle, the corner core arm 300a ₃ and 30
The angle θ between the plane including 0a ₄ and the plane including the corner core arms 300a ₄ and the side core arms 300a ₅ is smaller than a right angle. According to such a structure of the closed magnetic circuit core 300, the length d between the side core arms 300a ₁ and 300a _{5 of the} EMC filter can be shortened to reduce the size of the entire filter, and moreover, the common mode noise current can be reduced. The inductance can be increased, and as a result, the common mode noise current blocking ability can be improved.

FIG. 31 shows a twenty second embodiment of the EMC filter of the present invention.
It is a top view which shows the structure of the Example of this. In the figure, 310 is two parallel first core arms 310a.
₁ and 310a ₂ and two parallel second core arms 31
0b shows a flat closed magnetic circuit core.
The first core arms 310a ₁ and 310a ₂ and the second core arm 310b are connected to each other to form a (symmetrical) rectangular loop core. First core arm 310
a ₁ and 310 a ₂ are longer than the second core arm 310 b, and the first and second core arms 310 b
a ₁ and 310a ₂ and 310b form a closed magnetic circuit. The rectangular loop core 310 has an effective magnetic permeability μ equal to that of the conventional toroidal core 580 shown in FIG.

First core arms 310a ₁ and 310a
₂ includes one or more pairs of wires 311 forming a plurality of coils, each of which is connected to each wire of a multi-wire balanced communication wire (not shown).
Is wound. It should be noted that in FIG. 31 and the following figures, only one or several representative pairs are shown to facilitate understanding of the winding structure. Each pair of lines 311
Is a closed magnetic circuit core 310 when a common mode current flows.
The first core arms 310a ₁ and 310a ₂ are wound in such a winding direction that magnetic fluxes flow in the same direction.

First core arms 310a ₁ and 310a
₂ of each of which is divided into three sections along its axis. That is, two first sections Sb and Sc and one second section
Section Sa. Each of the first sections Sb and Sc is longer than the second section Sa. In the second section Sa located on the center side of each winding section of the first core arms 310a ₁ and 310a ₂ , each pair of wires 311a is concentrated (densely) in a multilayer structure without space between adjacent windings. It is wound. First core arm 310a ₁
, 310a ₂ and first sections Sb and Sc located on both sides of the second section Sa of each winding section, the pair lines 311b and 311c are distributed with a space between adjacent windings ( Coarsely) wound. Half of the pair of wires wound around the first core arms 310a ₁ and 310a ₂ are from the concentrated winding section Sa to the one distributed winding section S.
It is wound over b and the other half is the concentrated winding section S
It is wound from a to the other distributed winding section Sc.

The coil consisting of these pair wires is the first on the input side.
Signal input terminal (input terminal) T ₁ connected to the wire of the concentrated winding section Sa located at the center of the core arm 310a ₁ of
T _2, ..., T _m, has a T _n, concentrated winding sections Sa located at the first center core arms 310a ₂ of the other
Signal output terminals (output terminals) T ₁ ', T ₂ ', connected to the
.., T _m ′, T _n ′. The pair wire 311 is used for signal input ends T ₁ and T of the input-side first core arm 310a ₁ .
₂ , ..., T _m , T _n, from the output side first core arm 31
0a ₂ signal output terminals T ₁ ′, T ₂ ′, ..., T _m ′, T _n ′
It is heading toward one way without returning. That is, each pair of wires has signal input terminals T ₁ , T ₂ , ..., T _m , T _n.
Starting from the input core core 310a _{1 in} the concentrated winding section Sa, the windings are concentrated (densely) in a multi-layered structure with no space between adjacent windings, and then the distributed winding section S
b (Sc) is wound (coarsely) so as to be distributed with a space between adjacent windings and advances toward one end of the input-side first core arm 310a ₁ to output-side the first core arm 310a 1. _2nd , its output side first core arm 3
Between windings adjacent in the 10a ₂ distribution winding section Sb (Sc) so as to be distributed by providing a space (crude on) is wound, then no space between the windings adjacent in concentrated winding sections Sa In a multi-layered structure and concentrated (closely), and is wound toward the center of the input-side first core arm 310a ₁ , and then the signal output ends T ₁ ′, T ₂ ′, ..., T _m ′, T is configured to arrive at _n '.

As described above, when the EMC filter having the closed magnetic circuit core elongated in the lateral direction with respect to the input / output terminal is used, the connection for accommodating the EMC filter even in a multi-wire communication line having a large number of lines is provided. The connecting means and the like can be downsized without making the housing of the means and the like so large.
The lines 311 of each pair are arranged close to each other. Particularly in this embodiment, each pair of lines are parallel lines that are in close contact with each other.

When the common mode noise current flows through the paired wires, the magnetic fluxes flow in the first core arm 310 in the same direction and thus strengthen each other, so that the magnetic flux in the closed magnetic circuit 310 increases. Actually, a magnetic flux in the same direction is generated by a common mode noise current flowing through a coil not shown in FIG. As is apparent from FIG. 31, since each pair of wires is distributed and wound in the sections Sb and Sc, and is separately wound into the _{two first} core arms 310a ₁ and 310a ₂ , between the input and output ends thereof. The stray capacitance of Cs (combined capacitance of Cs _a , Cs _b and Cs _c ) is suppressed as a whole. As a result, even if the common mode noise current is a high frequency current, a large inductance effectively acts, and the noise current can be prevented from entering.

When the normal mode current flows through the pair wire, magnetic fluxes in mutually opposite directions are generated in the first core arms 310a ₁ and 3a.
Flow through 10a ₂ . Since the paired wires are parallel lines that are closely attached to each other and are wound in the same magnetic path, these magnetic fluxes have the same value and flow in the closed magnetic path 310 in opposite directions, so they cancel each other out. As a result, M≈L with respect to the normal mode current In, the leakage inductance Ld does not occur, and the insertion loss hardly occurs. Further, in this embodiment, since all the paired wires are wound symmetrically with respect to the center of the first core arms 310a ₁ and 310a ₂ , crosstalk can be effectively reduced.
Other configurations and operational effects of this embodiment are similar to those of the first embodiment of FIG.

FIG. 32 shows the twenty-third part of the EMC filter of the present invention.
It is a top view which shows the structure of the Example of this. In this embodiment, the shape of the closed magnetic circuit core 320 is different from that of the core 310 in the embodiment of FIG. That is, in this embodiment, the closed magnetic circuit core 320 is composed of a (symmetrical) substantially diamond-shaped loop core. The loop core is formed by connecting two first core arms 320a and two second core arms 320b shorter than the first core arms 320a to each other. Therefore, the distance between the two first core arms 320a is the largest in their central portions. Thus, the first core arm 32
Since a sufficient distance can be obtained between them in the central part of 0a, a large number of turns of the pair wire can be wound in multiple layers in this part. Therefore, even when the core size is small, a large number of turns can be wound in multiple layers, and the inductance can be greatly increased. Other configurations and operational effects of this embodiment are similar to those of the 22nd embodiment of FIG.

FIG. 33 shows the 24th part of the EMC filter of the present invention.
It is a top view which shows the structure of the Example of this. In this embodiment, the closed magnetic circuit core 330 is composed of a (symmetrical) oval or elliptical loop core formed by connecting two first core arms 330a and two second core arms 330b to each other. Except for the point
The configuration and effects of 1 and the like are exactly the same as in the case of the 23rd embodiment of FIG.

FIG. 34 is a twenty fifth embodiment of the EMC filter of the present invention.
It is a top view which shows the structure of the Example of this. In this embodiment, the structure of the closed magnetic circuit core 340 having the two parallel first core arms 340a and the two parallel second core arms 340b is exactly the same as that of the core 310 in the twenty-second embodiment of FIG. is there. Furthermore, each pair 3
The configuration of 41 itself is exactly the same as the configuration of the pair line 311 in the embodiment of FIG. However, in this embodiment, each pair wire 341 is wound around the core 340 with a winding structure different from that of the 22nd embodiment. That is, each pair of wires 34
1a is wound (coarsely) over the entire length of each of the first core arms 340a so as to have a space between adjacent windings and is (roughly) wound. The wire 341b is wound (densely) in a concentrated manner with almost no space between the windings adjacent to each other in multiple layers.

Since a sufficient distance can be obtained between the second core arms 340b, it is possible to wind a large number of pairs of wires in multiple layers. Therefore, even when the core size is small, a large number of turns can be wound in multiple layers, and the inductance can be greatly increased. The distributed winding section (first core arm) is the concentrated winding section (part of the second core arm).
Since it is sufficiently longer, it is possible to suppress an increase in stray capacitance as a whole. As a result, even if the common mode noise current is a high frequency current, a large inductance effectively acts, and the noise current can be prevented from entering. Other configurations and operational effects of this embodiment are similar to those of the 22nd embodiment of FIG.

FIG. 35 shows the twenty sixth embodiment of the EMC filter of the present invention.
It is a perspective view which shows the structure of the Example of this. In this embodiment, the structure of the closed magnetic circuit core 350 having the two parallel first core arms 350a and the two parallel second core arms 350b is exactly the same as that of the core 310 in the twenty-second embodiment of FIG. is there. Further, the distributed winding section (351b and 351) of the first core arm 350a is provided.
c) and each pair of wires 3 in the concentrated winding section (351a)
The winding structure of 51 is exactly the same as the winding structure of the pair wire 311 in the embodiment of FIG. However, in this embodiment, the auxiliary closed magnetic circuit core 352 of the rectangular loop is bridged between the two first core arms 350a at the central portion (concentrated winding section), and the paired wire 351a of the concentrated winding section is provided.
Is the auxiliary closed magnetic circuit core 3 in common with the first core arm 350a.
It is also wound around 52.

Despite a large stray capacitance in the common winding section, the increase of the stray capacitance as a whole is small, and the auxiliary core 352 has an appropriate magnetic permeability.
Since the common mode inductance in the low frequency range can be increased to the required value by using,
The deterioration of the high-frequency characteristic is small, and the blocking capability for the common mode noise current can be further broadened as a whole. Other configurations and operational effects of this embodiment are similar to those of the 22nd embodiment of FIG.

FIG. 36 shows the twenty-seventh portion of the EMC filter of the present invention.
It is a perspective view which shows the structure of the Example of this. In this embodiment, a closed magnetic circuit core 360 having two first core arms 360a and two second core arms 360b.
The configuration is exactly the same as the configuration of the core 320 in the twenty-third embodiment shown in FIG. Further, the first core arm 36
The winding structure of each pair wire 361 in the distributed winding section (361b and 361c) of 0a and the concentrated winding section (361a) is exactly the same as the winding structure of the pair wire 321 in the embodiment of FIG. However, in this embodiment, the auxiliary closed magnetic circuit core 362 having a rectangular loop is bridged between the two first core arms 360a at the central portion (concentrated winding section), and the paired wire 361a of the concentrated winding section is provided. Is also wound around the auxiliary closed magnetic circuit core 362 in common with the first core arm 360a.

Despite the large stray capacitance in the common winding section, the increase of the stray capacitance as a whole is small, and the auxiliary core 362 has an appropriate magnetic permeability.
Since the common mode inductance in the low frequency range can be increased to the required value by using,
The deterioration of the high-frequency characteristic is small, and the blocking capability for the common mode noise current can be further broadened as a whole. Other configurations and operational effects of this embodiment are similar to those of the 23rd embodiment of FIG.

FIG. 37 is a twenty-eighth example of the EMC filter of the present invention.
It is a perspective view which shows the structure of the Example of this. In this embodiment, the configuration of the closed magnetic circuit core 370 of the elliptical or elliptical loop having two first core arms 370a and two second core arms 370b is the same as that of the core 330 in the twenty-fourth embodiment of FIG. Exactly the same. Furthermore, the winding structure of the pair wire 371 is exactly the same as the winding structure of the pair wire 331 in the embodiment of FIG. However,
In this embodiment, the circular closed loop-shaped auxiliary closed magnetic circuit core 372 is bridged between the two first core arms 370a at the central portion (concentrated winding section), and the pair wire 371 of the concentrated winding section is formed. It is also wound around the auxiliary closed magnetic circuit core 372 in common with the first core arm 370a.

Despite a large stray capacitance in the common winding section, the increase in stray capacitance as a whole is small, and the auxiliary core 372 has an appropriate magnetic permeability.
Since the common mode inductance in the low frequency range can be increased to the required value by using,
The deterioration of the high-frequency characteristic is small, and the blocking capability for the common mode noise current can be further broadened as a whole. Other configurations and operational effects of this embodiment are similar to those of the twenty-fourth embodiment shown in FIG.

FIG. 38 shows the twenty-ninth embodiment of the EMC filter of the present invention.
It is a perspective view which shows the structure of the Example of this. In this embodiment, the structure of the closed magnetic circuit core 380 having the two parallel first core arms 380a and the two parallel second core arms 380b is exactly the same as that of the core 340 in the twenty-fifth embodiment of FIG. is there. Further, each paired wire 381 including a distributed winding (381a) provided over the entire length of each of the first core arms 380a and a concentrated winding (381b) provided in multiple layers on each of the second core arms 380b. The winding structure of the pair wire 3 in the embodiment of FIG.
The winding structure is the same as that of 41. However, in this embodiment, the two auxiliary closed magnetic circuit cores 3 of the rectangular loop are
82 is bridged between the two first core arms 380a at the end position thereof, that is, the position of the second core arm 380b (concentrated winding section), and the pair wire 381b of the concentrated winding section is provided.
Is the auxiliary closed magnetic circuit core 3 in common with the second core arm 380b.
It is also wound around 82.

Despite the large stray capacitance in the common winding section, the increase of the stray capacitance as a whole is small, and the auxiliary core 382 has an appropriate magnetic permeability.
Since the common mode inductance in the low frequency range can be increased to the required value by using,
The deterioration of the high-frequency characteristic is small, and the blocking capability for the common mode noise current can be further broadened as a whole. Other configurations and operational effects of this embodiment are similar to those of the 25th embodiment of FIG.

FIG. 39 shows E according to the second embodiment shown in FIG.
FIG. 58 shows the common mode noise current attenuation amount and normal mode current attenuation amount (indicated by A) of the MC filter with respect to frequency characteristics shown in FIG. (Shown in FIG. 4). As is clear from this figure, the EMC filter according to the present invention has excellent blocking characteristics for high-frequency common mode noise current and very small transmission loss for normal mode current.

FIG. 40 shows E according to the second embodiment shown in FIG.
The crosstalk attenuation amount characteristic (shown by A) of the MC filter is compared with the crosstalk attenuation amount characteristic (shown by B) by the conventional EMC filter using the ring-shaped toroidal core shown in FIG. FIG. As is clear from this figure, the EMC filter according to the present invention also has excellent blocking characteristics against crosstalk.

In the above embodiments, the paired wires are constituted by closely-attached parallel wires or twisted wires. However, the unbalance between the paired wires can be improved by collectively twisting the twisted wires. Therefore, the crosstalk attenuation characteristic can be further improved.

It is obvious that the EMC filter of the present invention can be constructed by arbitrarily combining some of the above-mentioned embodiments with each other.

Now, various application examples of the above-described EMC filter of the present invention will be described in detail.

FIG. 41 is an external perspective view of a conventional modular plug and a conventional modular jack. As shown in the figure, the modular plug connected to the multi-pair communication line 410 includes a plug housing 411 and a plug contact groove 4.
12 and a lock bar 413, the modular jack has a spring contact groove 416 that engages with the plug contact groove 412 when the jack housing 414 and the opening 415 for receiving the modular plug and the modular plug are coupled. And have.

FIG. 42 is a perspective view schematically showing a configuration of a first application example of the EMC filter according to the present invention. In this example, the EMC filter 423 is incorporated within a modular jack housing 424 that is connected to a multi-line balanced communication line such as ISDN, standard home bus, digital bus, analog communication line or TR cord. The modular jack housing 424 has an EMC filter 423.
41 has the same configuration as the housing 414 shown in FIG. 41 except that there is an internal space for mounting the. That is, the EMC filter 423 is provided on the back side (the side opposite to the opening for receiving the modular plug) in the housing 424 of the modular jack. The EMC filter 423 itself includes a pair of wires 42 that are concentratedly wound.
The structure of the EMC filter of the sixth embodiment shown in FIG. 12 is slightly modified so that 1a is located at one end of the center core arm 420c. In this example, since the EMC filter 423 is provided on the back side inside the modular jack housing 424, the EMC filter can be incorporated without increasing the height and width of the housing 424.

43 and 44 are a perspective view and an exploded perspective view showing the structure of the first application example of FIG. 42 more specifically. As shown in these drawings, the modular jack of this example includes a housing base 424a and a housing cover 424b. Housing base 424a
The spring terminal assembly 425, the divided cores 426a and 426b, the coil bobbin 427, and an EMC filter including a coil (not shown) are incorporated in the above. The spring terminal assembly 425 has the same number of spring contact terminals 428 as the number of multi-wire balanced communication lines to be connected. The coil bobbin 427 is
Coil winding portion 427a, spring contact terminal connecting terminal 427b, and printed wiring board connecting terminal 427c.
Is equipped with. Both ends of each coil (not shown) have terminals 42
7b and 427c are electrically connected respectively. The terminals 427b are electrically connected to the spring contact terminals 428, respectively. When assembling the modular jack, the spring terminal assembly 425 is first incorporated into the housing base 424a. Then, the EMC filter 42 electrically connected to the spring terminal 428.
3 is installed on the back side of the housing. After that, the housing cover 424b is attached, and fixing pins 429 for fixing the modular jack to, for example, a printed board are driven and fixed.

FIG. 45 is a perspective view schematically showing the configuration of a second application example of the EMC filter according to the present invention. In this example, the EMC filter 453 has a structure similar to that of the housing 424 shown in FIG. 42 except that the EMC filter 453 has an internal space for mounting the EMC filter not only on the back surface side but also on the top surface side. It is incorporated in the housing 454. That is, the EMC filter 453 is provided inside the housing 454 of the modular jack on the back side (the side opposite to the opening for receiving the modular plug) and the top side. In the EMC filter 453 itself, the center core arm 450c and the side core arm 450a are bent to have an L-shaped cross section, and the concentratedly wound pair wire 451a is located at the bent portion of the center core arm 450c. like,
The structure of the EMC filter of the sixth embodiment shown in FIG. 12 is slightly modified. According to this example, the EMC
Filter 453 is modular jack housing 454
Since they are provided on the back surface and the top surface side inside, the EMC filter can be incorporated without increasing the width of the housing 454.

FIGS. 46A and 46B are a perspective view and a sectional view schematically showing the configuration of the third application example of the EMC filter according to the present invention. In this example, the EMC filter 463 is incorporated within a modular jack housing 464 having a similar construction to the housing 424 shown in FIG. That is, the EMC filter 463 is provided in the housing 464 of the modular jack on the back side (opposite to the opening for receiving the modular plug) and the back top corner. The EMC filter 463 itself has an L-shaped cross section in which a center core arm 460c and a side core arm 460a are bent and has a concentrated winding pair wire 461a and an auxiliary closed magnetic circuit core 46.
The structure of the EMC filter of the eleventh embodiment shown in FIG. 17 is slightly modified so that 2 is located at the bent portion of the center core arm 460c. According to this example, since the main part of the EMC filter 463 is provided by utilizing the top surface corner in the modular jack housing 464, the dead space can be effectively used and the size of the housing 464 can be increased. It is possible to install an EMC filter without using it.

47A and 47B are a perspective view and a sectional view schematically showing the configuration of a fourth application example of the EMC filter according to the present invention. In this example, the EMC filter 473 is shown in FIG. 42 except that it additionally includes as many surge bypass path terminals 479 as the number of multi-wire balanced communication lines to which this modular jack is to be connected. It is incorporated in a modular jack housing 474 having a similar construction to the housing 424.

Each paired coil 47 of the EMC filter 473
One end of No. 1 and each surge bypass path terminal 479 are connected to each spring contact terminal 478. The other end of each paired wire coil 471 is connected to each printed wiring board connecting terminal 477 connected to each input terminal of a printed wiring board (not shown). Each surge bypass path terminal 479 is connected to a surge absorbing element (not shown) such as a varistor provided on the printed wiring board. According to such a configuration, the spring contact terminal 47
The high frequency common mode noise current that invaded via
The surge current blocked by the MC filter 473 and flowing in via the spring contact terminal 478 is bypassed through the surge bypass path terminal 479 without being applied to the coil of the EMC filter. Therefore, even when a large surge current is applied, it is possible to prevent the coil from being burnt out, and it is possible to simultaneously protect against both the interfering wave and the surge current. The surge bypass path terminal 479 does not necessarily have to be provided for all the paired wires, but may be provided only for the paired wires to which surge current easily arrives or need to be protected from the surge current. As a result, the modular jack housing can be downsized.

The EMC filter 473 is provided on the back side (opposite to the opening for receiving the modular plug) in the housing 474 of the modular jack. This E
The MC filter 473 itself is a pair of wires 471 that are concentratedly wound.
The structure of the EMC filter of the sixth embodiment shown in FIG. 12 is slightly modified so that a is located at one end of the center core arm 470c.

FIG. 48 is a perspective view schematically showing the structure of a fifth application example of the EMC filter according to the present invention and a part of which is cut away so that the EMC filter can be seen. In this example, the EMC filter 483 is incorporated into a modular jack housing 484 having a configuration similar to the housing 424 shown in FIG. 42 except that the top surface thereof has an internal space for mounting the EMC filter. ing. That is, the EMC filter 483 is provided on the top surface side inside the housing 484 of the modular jack. The EMC filter 483 itself has exactly the same configuration as the EMC filter of the fifteenth embodiment shown in FIGS. 21 and 22. By using the EMC filter in which the core is elongated in the lateral direction with respect to the input / output terminals as described above, the housing can be downsized without increasing the size of the multi-wire communication line having a large number of wires. it can.

FIG. 49 is a perspective view schematically showing the structure of a sixth application example of the EMC filter according to the present invention and a part of which is cut away so that the EMC filter can be seen. In this example, the EMC filter 493 has a structure similar to that of the housing 424 shown in FIG. 42 except that the EMC filter 493 has an internal space for mounting the EMC filter not only on the back surface side but also on the top surface side. It is incorporated in the housing 494. That is, the EMC filter 493 is a modular jack housing 494.
It is provided on the back side (opposite the opening for receiving the modular plug) and the top side. This EMC filter 493 itself has the same configuration as the EMC filter having the L-shaped cross section of the nineteenth embodiment shown in FIG.

FIG. 50 is a perspective view schematically showing the structure of a seventh application example of the EMC filter according to the present invention and a part of which is cut away so that the EMC filter can be seen. In this example, the EMC filter 503 is incorporated in a modular plug housing 501 having the same configuration as the housing 411 shown in FIG. 41 except that the EMC filter 503 has an internal space for mounting the EMC filter. This EMC filter 503 itself is shown in FIG. 21 and FIG.
The structure is exactly the same as that of the EMC filter of the fifteenth embodiment shown in FIG.

FIG. 51 is a perspective view schematically showing the structure of an eighth application example of the EMC filter according to the present invention and a part of which is cut away so that the EMC filter can be seen. In this example, the EMC filter 513 is RS-232D.
Housing 514 of a flat connector connected to a balanced communication line (not grounded) of multi-wires (4 in this example) such as
Built in. The EMC filter 513 itself has a configuration in which the structure of the EMC filter of the sixth embodiment shown in FIG. 12 is slightly modified so that the concentratedly wound pair wire 511a is located at one end of the center core arm 510c. ing.

FIG. 52 is a perspective view schematically showing the structure of a ninth application example of the EMC filter according to the present invention and a part of which is cut away so that the EMC filter can be seen. In this example, the EMC filter 523 is RS-232D.
Housing 524 of a flat connector connected to a balanced communication line (ungrounded) of multi-wires (4 in this example)
Built in. The EMC filter 523 itself has the same structure as the EMC filter of the fifteenth embodiment shown in FIGS. 21 and 22.

FIG. 53 is a perspective view schematically showing the structure of a tenth application example of the EMC filter according to the present invention and a part of which is cut away so that the EMC filter can be seen. In this example, the EMC filter 533 is RS-232.
It is incorporated in the housing 534 of the D-type sub-connector connected to a multi-wire balanced interface cable (non-ground) such as a C, GP-IB or Centronics specification cable. This EMC filter 533 itself has the same configuration as the EMC filter of the fifteenth embodiment shown in FIGS. 21 and 22.

FIG. 54 is a perspective view schematically showing a structure of an eleventh application example of the EMC filter according to the present invention and a part of which is cut away so that the EMC filter can be seen. In this example, the EMC filter 543 is an IC or LS.
It is incorporated in a housing 544 such as an I-chip.
The EMC filter 543 itself has the same structure as the EMC filter of the fifteenth embodiment shown in FIGS. 21 and 22.

FIG. 55 is a perspective view schematically showing the structure of a twelfth application example of the EMC filter according to the present invention and showing a part of the EMC filter so that the EMC filter can be seen. In this example, the EMC filter 553 is a housing 5 of a multi-terminal connector used for mounting a printed wiring board or the like.
It is incorporated in 54. In the figure, 555 indicates a U-shaped or U-slit connection terminal when inserting a printed wiring board, and 556 indicates an external connection terminal.
The EMC filter 553 itself has the same structure as the EMC filter of the fifteenth embodiment shown in FIGS. 21 and 22.

56A and 56B schematically show the structure of a thirteenth application example of the EMC filter according to the present invention, and a perspective view and a sectional view in which a part of the EMC filter is cut away so that the EMC filter can be seen. Is. In this example, a thin EM
The C filter 563 is directly incorporated in the printed wiring board 564. As a result, the printed wiring board 56
The common mode noise current flowing through the transmission line 4 can be blocked without increasing the thickness of the printed wiring board. The EMC filter 563 itself has the same structure as the EMC filter of the fifteenth embodiment shown in FIGS. 21 and 22.

57 (A) and 57 (B) schematically show the structure of a fourteenth application example of the EMC filter according to the present invention, and a perspective view and a cross-sectional view with a part cut away so that the EMC filter can be seen. Is. In this example, a thin EM
The C filter 573 is directly incorporated in the flat cable 574. As a result, the common mode noise current flowing in the flat cable 574 is EM
It can be blocked without providing a special connector for the C filter. In these figures, 575 shows the core wire of the cable 574, and 576 shows the coating of the cable. This EMC filter 573 itself is
It has the same structure as the EMC filter of the fifteenth embodiment shown in FIGS.

In the above-described application example of the EMC filter of the present invention, the EMC filter according to the specific embodiment is a modular jack, a modular plug, a flat connector, a D-type sub-connector, an IC (LSI) chip,
Although incorporated into a multi-terminal connector, a printed wiring board, or a flat cable, it is clear that the EMC filter of any of the embodiments described above may be incorporated into any of these components.

As described above, the EMC filter of the present invention prevents the entry of common mode noise currents by being incorporated in the connecting means such as a communication line, the housing of various components, or directly incorporated in the components. It becomes possible to prevent effectively. Particularly, with respect to the conventional filter that is grounded by a shield member or the like to prevent noise, the EMC filter of the present invention can easily prevent noise even in a non-grounded state.

The examples described above are merely illustrative and not limitative of the present invention, and the present invention can be implemented in various other modified modes and modified modes. Therefore, the scope of the present invention is defined only by the claims and their equivalents.

[0136]

As described above in detail, according to the present invention, an EMC filter for a multi-line balanced communication line has at least one first core arm constituting a closed magnetic path and a length equal to or less than a length of the first core arm. A closed flat magnetic circuit core having a second core arm having a length of 1 and a plurality of coils each including at least one pair of wires. The paired wires are located close to each other and are wound around the closed magnetic circuit core so that the magnetic flux flows in the same direction in the closed magnetic circuit when current flows in the same direction in the paired wires of each coil. Has been done. Furthermore, these lines run in one direction from the signal input end of the coil to the signal output end. Therefore, according to the present invention, since the paired wires for transmitting signals are located close to each other and wound on the same closed magnetic circuit core,
No leakage magnetic flux is generated. For this reason, the transmission loss for high-speed or high-frequency signal transmission is suppressed to a low level, and signal transmission in the high-frequency region becomes possible.

[Brief description of drawings]

FIG. 1 is a plan view showing a schematic configuration of a first embodiment of an EMC filter of the present invention.

FIG. 2 is an electrical equivalent circuit diagram of the EMC filter shown in FIG.

FIG. 3 is a diagram showing a relationship between _a ratio of lengths of concentrated winding sections l _a / l ₀ and a ratio of stray capacitances Cs / Cs ₀ .

FIG. 4 is a diagram illustrating a winding structure of each pair of wires wound around a core in the distributed winding section of FIG.

FIG. 5 is a diagram showing a relationship between a space ratio h / l _b between adjacent windings and a stray capacitance ratio Cs / Cs _st in a unidirectional winding structure and a return winding structure.

FIG. 6 is a plan view illustrating the operation of the EMC filter according to the embodiment of FIG. 1 with respect to the common mode noise current Ic and the normal mode current In.

7 is a diagram showing frequency characteristics of common mode attenuation and normal mode attenuation of the EMC filter shown in FIG.

FIG. 8 is a plan view showing a schematic configuration of a second embodiment of the EMC filter of the present invention.

FIG. 9 is a plan view showing a schematic configuration of a third embodiment of the EMC filter of the present invention.

FIG. 10 is a plan view showing a schematic configuration of a fourth embodiment of the EMC filter of the present invention.

FIG. 11 is a plan view showing a schematic configuration of a fifth embodiment of the EMC filter of the present invention.

FIG. 12 is a plan view showing a schematic configuration of a sixth embodiment of the EMC filter of the present invention.

FIG. 13 is a plan view showing a schematic configuration of a seventh embodiment of the EMC filter of the present invention.

FIG. 14 is a plan view showing a schematic configuration of an eighth embodiment of the EMC filter of the present invention.

FIG. 15 is a plan view showing a schematic configuration of a ninth embodiment of the EMC filter of the present invention.

FIG. 16 is a plan view showing a schematic configuration of a tenth embodiment of the EMC filter of the present invention.

FIG. 17 is a plan view showing a schematic configuration of an eleventh embodiment of the EMC filter of the present invention.

FIG. 18 is a plan view showing a schematic configuration of a twelfth embodiment of the EMC filter of the present invention.

FIG. 19 is a plan view showing a schematic configuration of a thirteenth embodiment of the EMC filter of the present invention.

FIG. 20 is a plan view showing a schematic configuration of a fourteenth embodiment of the EMC filter of the present invention.

FIG. 21 is a perspective view showing a schematic configuration of a fifteenth embodiment of the EMC filter of the present invention.

22 is an exploded perspective view showing more specifically the fifteenth embodiment of FIG. 21. FIG.

FIG. 23 is a plan view illustrating the operation of the EMC filter according to the embodiment of FIG. 21 with respect to the common mode noise current Ic and the normal mode current In.

FIG. 24 is a perspective view showing a schematic configuration of a sixteenth embodiment of the EMC filter of the present invention.

FIG. 25 is a perspective view showing a schematic configuration of a seventeenth embodiment of the EMC filter of the present invention.

FIG. 26 is a perspective view showing a schematic configuration of an eighteenth embodiment of the EMC filter of the present invention.

FIG. 27 is a plan view illustrating the operation of the EMC filter according to the embodiment of FIG. 26 with respect to the common mode noise current Ic and the normal mode current In.

FIG. 28 is a perspective view showing a schematic configuration of a nineteenth embodiment of the EMC filter of the present invention.

FIG. 29 is a perspective view showing a schematic configuration of a twentieth embodiment of the EMC filter of the present invention.

FIG. 30 is a sectional view showing a schematic configuration of a twenty-first embodiment of the EMC filter of the present invention.

FIG. 31 is a plan view showing a schematic configuration of a twenty-second embodiment of the EMC filter of the present invention.

FIG. 32 is a plan view showing a schematic configuration of a twenty-third embodiment of the EMC filter of the present invention.

FIG. 33 is a plan view showing a schematic configuration of a twenty-fourth embodiment of the EMC filter of the present invention.

FIG. 34 is a plan view showing a schematic configuration of a twenty-fifth embodiment of the EMC filter of the present invention.

FIG. 35 is a perspective view showing a schematic configuration of a twenty-sixth embodiment of the EMC filter of the present invention.

FIG. 36 is a plan view showing a schematic configuration of a twenty-seventh embodiment of the EMC filter of the present invention.

FIG. 37 is a plan view showing a schematic configuration of a twenty-eighth embodiment of the EMC filter of the present invention.

FIG. 38 is a plan view showing a schematic configuration of a twenty-ninth embodiment of the EMC filter of the present invention.

FIG. 39 is a diagram showing frequency characteristics of common mode noise current attenuation and normal mode current attenuation of the EMC filter according to the embodiment shown in FIG. 8 and the conventional EMC filter.

FIG. 40 is a diagram showing the frequency characteristics of the crosstalk attenuation amount of the EMC filter according to the embodiment shown in FIG. 8 and the conventional EMC filter.

FIG. 41 is an external perspective view of a conventional modular plug and a conventional modular jack.

FIG. 42 is a perspective view showing a schematic configuration of a first application example of the EMC filter according to the present invention.

43 is a perspective view showing more specifically the structure of the first application example of FIG. 42. FIG.

FIG. 44 is an exploded perspective view showing the structure of the first application example of FIG. 42 more specifically.

FIG. 45 is a perspective view showing a schematic configuration of a second application example of the EMC filter according to the present invention.

FIG. 46 is a perspective view and a sectional view showing a schematic configuration of a third application example of the EMC filter according to the present invention.

FIG. 47 is a perspective view and a sectional view showing a schematic configuration of a fourth application example of the EMC filter according to the present invention.

48 is a partially cutaway perspective view showing a schematic configuration of a fifth application example of the EMC filter according to the present invention. FIG.

FIG. 49 is a partially cutaway perspective view showing a schematic configuration of a sixth application example of the EMC filter according to the present invention.

FIG. 50 is a partially cutaway perspective view showing a schematic configuration of a seventh application example of the EMC filter according to the present invention.

FIG. 51 is a partially cutaway perspective view showing a schematic configuration of an eighth application example of the EMC filter according to the present invention.

52 is a partially cutaway perspective view showing a schematic configuration of a ninth application example of the EMC filter according to the present invention. FIG.

FIG. 53 is a partially cutaway perspective view showing a schematic configuration of a tenth application example of the EMC filter according to the present invention.

FIG. 54 is a partially cutaway perspective view showing a schematic configuration of an eleventh application example of the EMC filter according to the present invention.

FIG. 55 is a partially cutaway perspective view showing a schematic configuration of a twelfth application example of the EMC filter according to the present invention.

FIG. 56 is a partially cutaway perspective view and a sectional view showing a schematic configuration of a thirteenth application example of the EMC filter according to the present invention.

FIG. 57 is a partially cutaway perspective view and a sectional view showing a schematic configuration of a fourteenth application example of the EMC filter according to the present invention.

FIG. 58 is a perspective view and a sectional view showing a schematic configuration of a conventional choke coil filter using a toroidal core.

59 is an electrically equivalent circuit of the choke coil shown in FIG.

FIG. 60 is a perspective view showing a schematic configuration of a conventional choke coil filter using a flat plate-shaped through core.

FIG. 61 is a perspective view showing a schematic configuration of a conventional choke coil filter using a cylindrical through core.

[Explanation of symbols]

10 closed magnetic path core 10a first core arms 10b second core arms 11, 11a, 11b, 11c to-line _{T 1, T 2, ...,} T i, T j, ..., T m, T n signal input terminal T ₁ ' , T ₂ ', ..., T _i ', T _j ', ..., T _m ', T _n '

Claims (9)

[Claims] 1. At least one first forming a closed magnetic circuit
A flat magnetic closed core having a core arm and a second core arm having a length equal to or less than the length of the first core arm, and a plurality of coils each including at least one pair of wires, The pair of lines are located close to each other, and the magnetic flux flows in the same direction in the closed magnetic circuit when current flows in the same line in the pair of coils. An EMC filter for a multi-line balanced communication line, wherein the EMC filter is wound around a core, and further, the wire extends in one direction from a signal input end of the coil toward a signal output end. 2. The signal input end is located at one end of the first core arm, and the signal output end is the first core arm.
Is located at the other end of the core arm, so that each of the wires starts from the signal input end, winds around the first core arm, advances in the axial direction of the first core arm, and reaches the signal output end. The EMC filter for a multi-line balanced communication line according to claim 1, wherein the EMC filter is configured as follows. 3. The first core arm comprises at least an input side core arm and an output side core arm, the signal input end is located along the input side core arm, and the signal output end is at the output side core arm. Are wound along each of the lines, starting from the signal input end and wound so that magnetic flux is generated in the same direction in the input side core arm and the output side core arm from the input side core arm to the output side core arm. The multi-line balanced communication line EMC filter according to claim 1, wherein the EMC filter is configured to arrive at the signal output end. 4. The first core arm comprises at least an input side core arm and an output side core arm, the signal input end is located at the center of the input side core arm, and the signal output end is the output side core arm. Is located at the center of the input side core arm and is wound around the input side core arm, goes to one end of the input side core arm, and extends over the output side core arm to the output side core arm. The multi-line balanced communication line EM according to claim 1, wherein the EM for a multi-line balanced communication line is configured so as to be rotated and proceed to a central portion of the output side core arm to reach the signal output end.
C filter. 5. The multi-line balanced communication line E according to claim 1, wherein each pair of wires is constituted by a pair of parallel wires in close contact with each other.
MC filter. 6. The multi-line balanced communication wire E according to claim 1, wherein the wires forming each pair are formed by twisted wire pairs.
MC filter. 7. The first core arm is composed of a first section and a second section, and each pair of wires is distributed with a space between adjacent windings in the first section. It is wound by being wound up, and it is characterized by the above-mentioned.
An EMC filter for a multi-line balanced communication line according to any one of 1. 8. The multi-filament balance according to claim 7, wherein each pair of wires is concentrated and wound between adjacent windings in the second section without a space. EMC filter for communication line. 9. The pair of wires are wound in a distributed manner with a space between adjacent windings in the first core arm, and a space is provided between adjacent windings in the second core arm. The EMC filter for a multi-line balanced communication line according to any one of claims 1 to 6, wherein the EMC filter is wound in a concentrated manner.