JP7219422B2 - multi-pair cable - Google Patents

Description

The present invention relates to multi-pair cables.

A multi-pair cable having a plurality of cables for differential signal transmission is known.

In a multi-pair cable with multiple cables for differential signal transmission, it is desirable to twist the cables for differential signal transmission so that they can be easily bent. When the number of differential signal transmission cables is large, multiple differential signal transmission cables are twisted together to form an inner layer, and multiple differential signal transmission cables are wound around the inner layer. Generally, an outer layer is formed to form a multi-layer structure.

For example, in a 4-channel multi-pair cable, a total of 8 differential signal transmission cables, 4 for transmission and 4 for reception, are used. Generally, an inner layer is formed, and an outer layer is formed by spirally winding six differential signal transmission cables around the inner layer.

In addition, there exists patent document 1 as prior art document information relevant to the invention of this application.

JP 2011-142070 A

By the way, in the above-mentioned 4-channel multi-pair cable, the two differential signal transmission cables used in the inner layer are twisted so as to be in direct contact with each other. Since the differential signal transmission cables are always placed close to each other, the electromagnetic field leaking from one differential signal transmission cable can easily affect the other differential signal transmission cable, resulting in crosstalk. There is a problem that the influence of

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the above problems and to provide a multi-pair cable capable of reducing the influence of crosstalk.

The present invention has been devised to achieve the above objects, and includes: an inner layer portion obtained by twisting two cables for differential signal transmission for inner layers together; and a pressure winding tape wound around the inner layer portion. and an outer layer portion formed by winding a plurality of cables for differential signal transmission for outer layers around the outer periphery of the pressure winding tape, wherein the differential signal transmission for the two inner layers A buffer tape is provided between the cables, and the pressure winding tape is spirally wound in a direction opposite to the twisting direction of the inner layer portion, so that the buffer tape is held in an S shape. , the two cables for differential signal transmission for the inner layer are displaced in the longitudinal direction in a cross-sectional view.

The twist direction of the inner layer portion may be the same as the winding direction of the outer layer portion.

The buffer tape may be made of foamed tape made of foamed resin.

The buffer tape may be made of an electrically conductive material.

The pressing tape may be made of a conductive material.

According to the present invention, it is possible to provide a multi-pair cable capable of reducing the influence of crosstalk.

1 is a cross-sectional view of a multi-pair cable according to one embodiment of the invention; FIG. (a) is a diagram for explaining a method of manufacturing the multi-pair cable of FIG. 1, (b) is a cross-sectional view along line 2B-2B, and (c) is a cross-sectional view along line 2C-2C. FIG. 4 is a diagram showing the result of simulating the distribution of current components in the common mode of the cable for differential signal transmission used as the inner layer core.

An embodiment of the present invention will be described below with reference to the accompanying drawings.

(Overall configuration of multi-pair cable)
FIG. 1 is a cross-sectional view of a multi-pair cable according to this embodiment.

As shown in FIG. 1, the multi-pair cable 1 includes an inner layer portion 3 in which two inner layer cables for differential signal transmission 2 are twisted together, and a pressure winding tape 7 wound around the inner layer portion 3. , and an outer layer portion 4 formed by winding a plurality of differential signal transmission cables 2 for outer layers around the outer periphery of a pressing winding tape 7 .

The differential signal transmission cable 2 includes two signal lines 5 arranged in parallel, and an insulator 6 that collectively or individually covers the two signal lines 5 . Here, a differential signal transmission cable 2 in which two signal lines 5 are collectively covered with an insulator 6 is used. As the insulator 6, for example, one made of foamed polyethylene can be used.

The differential signal transmission cable 2 is formed in an elliptical shape when viewed in cross section. However, not limited to this, the differential signal transmission cable 2 is formed in an elliptical shape in cross section (a shape consisting of two parallel straight lines facing each other and an arc connecting the ends of the straight lines). may be Hereinafter, the differential signal transmission cable 2 for the inner layer is referred to as an inner layer core 2a, and the differential signal transmission cable 2 for the outer layer is referred to as an outer layer core 2b.

In this embodiment, two inner layer cores 2a are arranged so that their longitudinal directions are aligned with each other and twisted together to form the inner layer portion 3, and six outer layer cores 2b are spirally wound (horizontally wound). A total of eight cables 2 for differential signal transmission are used to form a multi-pair cable 1 for four channels. However, the number of outer layer cores 2b is not limited to this. In this embodiment, the two-layer structure of the inner layer portion 3 and the outer layer portion 4 is used.

A pressing winding tape 7 is spirally wound around the inner layer portion 3 . In this embodiment, a resin tape in which an adhesive layer is formed on one surface of an insulating resin is used as the pressing tape 7 . The pressing tape 7 serves as a buffer layer when the outer core 2b is wound around the outer periphery of the inner layer portion 3, and suppresses deformation of the inner core 2a.

In this embodiment, the twist direction of the inner layer core 2a and the winding direction of the outer layer core 2b are the same, but they may be opposite directions. A sheath 8 is provided on the outer periphery of the outer layer portion 4 . Between the outer layer portion 4 and the sheath 8, a pressing winding, a shield layer, or the like may be provided as appropriate.

(Explanation of buffer tape)
Now, in the multi-pair cable 1 according to this embodiment, the buffer tape 9 is provided between the two inner layer cores 2a. The buffer tape 9 is twisted together with the inner layer core 2a to form a part of the inner layer portion 3. As shown in FIG.

By providing the buffer tape 9, the two inner layer cores 2a are in indirect contact via the buffer tape 9, and the distance between the two inner layer cores 2a is increased. It is possible to suppress the influence of the field on the other inner layer core 2a and reduce the influence of crosstalk.

In this embodiment, a foam tape made of foam resin is used as the buffer tape 9 . Examples of foamed resins used for foamed tapes include foamed polypropylene.

In the present embodiment, the buffer tape 9 has one side end along the outer peripheral surface of one inner layer core 2a and the other side end along the outer peripheral surface of the other inner layer core 2a. They are arranged in an S shape when viewed in cross section. The buffer tape 9 is wider than the inner core 2a in the longitudinal direction, and the side ends of the buffer tape 9 are arranged to extend at least to the center of the inner core 2a in the minor axis direction. It is

Further, in this embodiment, the two inner layer cores 2a are arranged so that the center lines A, which are equidistant from the two signal lines 5 in a cross-sectional view, do not match (shift in the longitudinal direction). In other words, the two inner layer cores 2a are arranged so that their centers (major axis direction and minor axis direction centers) do not face each other. By arranging the buffer tapes 9 in an S shape in a cross-sectional view, the positions of the two inner layer cores 2a are more easily displaced in the longitudinal direction than when the buffer tapes 9 are not arranged. It becomes difficult for the center line A of 2a to match. The effect of not matching the center lines A of the two inner layer cores 2a will be described later.

(Explanation of manufacturing method of multi-pair cable 1)
As shown in FIGS. 2A to 2C, when manufacturing the multi-pair cable 1, first, the two inner layer cores 2a and the buffer tape 9 are fed into a die 21 and rotated to form the inner layer portion 3. is formed, and a pressure winding tape 7 is helically wound around the inner layer portion 3 pulled out from the die 21. - 特許庁By winding the pressing winding tape 7 around the inner layer portion 3 pulled out from the die 21, the buffer tape 9 is held in an S-shape.

At this time, the twisting direction of the inner layer portion 3 and the winding direction of the pressure winding tape 7 are opposite to each other. Assuming that the twisting direction of the inner layer portion 3 and the winding direction of the pressure tape 7 are the same (that is, when the pressure tape 7 is wound clockwise in FIG. 2(c)), the side edge of the buffer tape 9 This is because there is a case where the portion is separated from the inner layer core 2a and the S-shaped shape cannot be maintained.

After winding a presser winding tape 7 around the inner layer 3, six outer layer cores 2b are wound around the outer circumference of the presser winding tape 7 to form an outer layer 4, and a sheath 8 is provided on the outer circumference of the outer layer 4. , the multi-pair cable 1 according to this embodiment is obtained.

(Effect of Not Aligning Center Lines A of Two Inner Layer Cores 2a)
FIG. 3 is a diagram showing the result of simulating the distribution of common-mode current components in the differential signal transmission cable 2 used as the inner layer core 2a. In FIG. 3, the magnitude of the current component in the common mode is indicated by the shading of the gray scale, and the darker the shading (closer to the signal line 5), the greater the current component in the common mode. .

As shown in FIG. 3, on the surface of the differential signal transmission cable 2 used as the inner layer core 2a (the outer peripheral surface of the insulator 6), the common-mode current component that causes crosstalk is It is large in the vicinity of the upper and lower positions, that is, in the vicinity of the position overlapping the signal line 5 in the minor axis direction (regions A1 to A4 surrounded by broken lines in FIG. 3).

When both inner layer cores 2a are arranged so that the center lines A of the two inner layer cores 2a coincide with each other, the portions where the common-mode current component is large face each other and are arranged closest to each other, resulting in crosstalk between the two inner layer cores 2a. may become large.

In this embodiment, the two inner layer cores 2a are shifted in the longitudinal direction so that the center lines A do not coincide with each other, so that the portions with large common-mode current components that cause crosstalk do not face each other and are separated from each other. Both inner layer cores 2a are arranged so that crosstalk can be further reduced.

Here, as an example, the case of using the differential signal transmission cable 2 having a structure in which the common-mode current component is increased in the areas A1 to A4 above and below both signal lines 5 is shown, but the differential signal transmission cable 2 is used as the inner layer core 2a. If the structure of the differential signal transmission cable 2 is different, the position where the common-mode current component becomes large is also different. For example, in a differential signal transmission cable having a structure in which two signal lines 5 are individually covered with insulators 6 and a drain line is arranged between the insulators 6, the most common mode current around the drain lines is components tend to be large.

Even in the case of using differential signal transmission cables having such different structures, if the two inner layer cores 2a are of the same structure as the differential signal transmission cables, the two inner layer cores 2a will have the same phase. Since the position where the current component of the mode becomes large is the same position (for example, the above-mentioned regions A1 to A4 and the periphery of the drain line), by arranging the two inner layer cores 2a so that the center lines A do not coincide, It is possible to reduce crosstalk by not facing the positions where the common-mode current component becomes large.

(Description of effects of the present embodiment)
As described above, in the multi-pair cable 1 according to this embodiment, the buffer tape 9 is provided between the two inner layer cores 2a.

By providing the buffer tape 9, the two inner layer cores 2a do not come into direct contact with each other, and the distance between the two inner layer cores 2a increases. It is possible to reduce the impact.

Further, in this embodiment, the two inner layer cores 2a are arranged so that the center lines A do not coincide with each other. As a result, both inner layer cores 2a can be arranged so that the portions where the common-mode current component increases are separated from each other without facing each other, and it is possible to further suppress the influence of crosstalk without increasing the cable outer diameter. become. Note that the thickness of the buffer tape 9 can be appropriately adjusted in consideration of the allowable outer diameter of the cable and the like.

In addition, in this embodiment, since the buffer tape 9 is arranged in an S shape when viewed in cross section, both inner layer cores 2a can be easily arranged so that the center lines A do not coincide with each other.

The multi-pair cable 1 according to the present embodiment is, for example, a cable assembly used in routers, switches, and servers installed in data centers, etc., and a cable assembly (direct attach cable) used for wiring personal computers, hard disks, etc. Applicable. Also, the multi-pair cable 1 can be applied to a cable device such as an active cable. A cable assembly is a cable with connectors integrated at both ends, and an active cable is a connector that actively compensates for and outputs electrical signals according to the loss characteristics of the cable for differential signal transmission. It is equipped with a compensation circuit that

The present invention is not limited to the above embodiments, and various modifications can be made without departing from the scope of the present invention.

For example, in the above embodiment, the foam tape is used as the cushioning tape 9, but the cushioning tape 9 may be made of a conductive material and have a shielding function. As a result, the inner layer cores 2a are electrically shielded, so that the influence of crosstalk can be reduced. As the buffer tape 9 made of a conductive material, for example, a metal tape in which a metal layer is formed on one side of a resin layer, a resin tape using a conductive resin, or the like can be used.

In the above-described embodiment, the resin tape is used as the pressing tape 7. However, the pressing tape 7 may be made of a conductive material and have a shielding function. good. As a result, the inner layer core 2a and the outer layer core 2b are electrically shielded, so that the influence of crosstalk between the inner layer core 2a and the outer layer core 2b can be reduced. As the pressing tape 7 made of a conductive material, for example, a metal tape having a metal layer formed on one surface of a resin layer, a resin tape using a conductive resin, or the like can be used. It should be noted that a conductive tape may be wound around the circumference of the presser winding tape 7 made of a resin tape.

(Summary of embodiment)
Next, the technical ideas grasped from the embodiments described above will be described with reference to the reference numerals and the like in the embodiments. However, each reference numeral and the like in the following description do not limit the constituent elements in the claims to the members and the like specifically shown in the embodiment.

[1] An inner layer portion (3) in which two cables for differential signal transmission for inner layers (2) are twisted together, a holding tape (7) wound around the inner layer portion (3), A multi-pair cable (1) comprising an outer layer portion (4) formed by winding a plurality of differential signal transmission cables (2) for outer layers around the outer circumference of the pressure winding tape (7), A multi-pair cable (1) in which a buffer tape (9) is provided between two inner-layer differential signal transmission cables (2).

[2] The differential signal transmission cable (2) includes two signal lines (5) arranged in parallel and an insulator ( 6), wherein the two inner-layer differential signal transmission cables (2) do not coincide with the center lines (A) that are equidistant from the two signal lines (5) in a cross-sectional view. A multi-pair cable (1) according to [1], which is arranged to:

[3] The buffer tape (9) has one side end along the outer peripheral surface of the differential signal transmission cable (2) for one of the inner layers and the other side end of the other inner layer. The multi-pair cable (1) according to [1] or [2], which is arranged in an S shape in cross section along the outer peripheral surface of the cable for differential signal transmission (2).

[4] The pressure winding tape (7) is spirally wound around the inner layer (3), and the twisting direction of the inner layer (3) and the winding direction of the pressure winding tape (7) multi-pair cable (1) according to [3], wherein the

[5] The multi-pair cable (1) according to any one of [1] to [4], wherein the buffer tape (9) is a foamed tape made of foamed resin.

[6] A multi-pair cable (1) according to any one of [1] to [5], wherein the buffer tape (9) is made of a conductive material.

[7] The multi-pair cable (1) according to any one of [1] to [6], wherein the pressing tape (7) is made of a conductive material.

1 Multi-pair cable 2 Cable for differential signal transmission 3 Inner layer 4 Outer layer 7 Holding tape 9 Buffer tape

Claims (5)

an inner layer portion formed by arranging and twisting two inner layer cables for differential signal transmission, which are formed in an elliptical shape in a cross-sectional view, such that their long axis directions are aligned with each other;
a pressure winding tape wound around the inner layer;
and an outer layer portion formed by winding a plurality of differential signal transmission cables for outer layers around the outer periphery of the pressure winding tape,
A buffer tape twisted together with the two inner-layer differential signal transmission cables is provided between the two inner-layer differential signal transmission cables,
The buffer tape is larger than the width of the two inner-layer differential signal transmission cables in the long-axis direction and is centered in the short-axis direction of the two inner-layer differential signal transmission cables. one side end of the buffer tape is arranged along one outer peripheral surface of the two inner-layer differential signal transmission cables, and the other side end of the buffer tape is arranged along the outer peripheral surface of the other of the two inner-layer differential signal transmission cables,
The two cables for differential signal transmission for the inner layer are arranged to be shifted in the longitudinal direction in a cross-sectional view, and the pressure winding tape is helically shaped in a direction opposite to the twisting direction of the inner layer. By being wound around, the buffer tape is held in an S-shaped shape,
Multi-pair cable. The pressure winding tape is spirally wound around the inner layer,
The twist direction of the inner layer portion and the winding direction of the outer layer portion are the same,
A multi-pair cable according to claim 1. The buffer tape is made of foamed tape made of foamed resin,
A multi-pair cable according to claim 1 or 2. The buffer tape is made of a conductive material,
A multi-pair cable according to claim 1 or 2 . The pressure winding tape is made of a conductive material,
A multi-pair cable according to any one of claims 1 to 4.

Images