JP2021099974A - Multicore communication cable - Google Patents

Abstract

To provide a multicore communication cable applicable to a transmission cable for high-speed signal transmission in compliance with a USB Type-C standard and having a plurality of coaxial wires, the multicore communication cable capable of realizing an improvement of transmission characteristics of a high-speed digital signal of 10 Gbps or faster, downsizing of a diameter, and improvement of flexibility.SOLUTION: A multicore communication cable 50 includes: an inner layer collective wire 10 including a power line 11, a ground line 12 and a twisted pair line 13, and covered by an inner layer press wound tape 14; an outer layer collective wire 20 arranged outside the inner layer collective wire 10 in a circumferential manner, including four or more sets of coaxial wire sets 22 composed of two coaxial wires 21, 21, and covered by an outer layer press wound tape 24; a shield layer 30 covering an outside of the outer layer collective wire 20; and a casing sheath 40. Twisting directions of the inner layer collective wire 10 and the outer layer collective wire 20 are opposite.SELECTED DRAWING: Figure 1

Description

The present invention relates to a multi-core communication cable applied as a transmission cable conforming to the USB Type-C standard. Specifically, the present invention is applied as a transmission cable for high-speed signal transmission conforming to the USB Type-C standard, and is a multi-core communication cable having a plurality of coaxial electric wires, and has transmission characteristics of a high-speed digital signal of 10 Gbps or more. It is related to the multi-core communication cable that can realize the improvement of the diameter, the reduction of the diameter and the improvement of the flexibility.

As a transmission cable compliant with the USB (Universal Serial Bus) Type-C standard, a coaxial line and a power supply line are arranged in a circumferential shape, and a signal line, a twisted pair line, and a ground line are arranged inside the coaxial line and a power supply line. Are known. For example, Patent Document 1 proposes a transmission cable capable of reducing costs and improving transmission characteristics. This transmission cable is a transmission cable compliant with the USB Type-C standard, and is provided in an outer gap formed between eight coaxial wires arranged in a circumferential shape and coaxial wires adjacent to each other. The first to fourth signal lines, the power supply line, the two ground lines, and the gathering line arranged inside the coaxial line including the twisted pair wire, and the set line arranged inside the coaxial line, are arranged. It includes a first shield layer that covers the assembly line, a second shield layer that covers the first to eighth coaxial lines and the first to fourth signal lines, and includes first to fourth signal lines. Two coaxial wires are interposed between them.

JP-A-2017-10747

The technique described in Patent Document 1 has a problem that the transmission characteristics are inferior because the distance between the electric wires constituting the centrally collected collective lines is short and the coupling between the electric wires is large. Further, the first shield layer is composed of a metal foil, a metal braid, or a horizontal winding shield and covers the outer circumference of the gathering line over the entire circumference, which hinders flexibility and diameter reduction. , Transmission characteristics at the time of bending tend to deteriorate.

The present invention solves the above problems, and an object thereof is a multi-core communication cable which is applied as a transmission cable for high-speed signal transmission compliant with the USB Type-C standard and has a plurality of coaxial electric wires. Another object of the present invention is to provide a multi-core communication cable capable of improving the transmission characteristics of a high-speed digital signal of 10 Gbps or more, reducing the diameter, and improving the flexibility.

The multi-core communication cable according to the present invention includes a power supply line, a ground wire, and a twisted pair wire, and is arranged in a circumferential shape on the outer side of the inner layer aggregated stranded wire covered with the inner layer holding tape and the inner layer aggregated stranded wire. The outer layer aggregate stranded wire, which includes four or more sets of coaxial electric wires composed of two coaxial wires, and is covered with a presser foot tape for the outer layer, and a shield layer and an outer sheath that cover the outside of the outer layer aggregate stranded wire. It is a multi-core communication cable having the above, characterized in that the twisted directions of the inner layer aggregated stranded wire and the outer layer aggregated stranded wire are opposite.

If the twisting directions of the inner layer aggregated stranded wire and the outer layer aggregated stranded wire are the same, the shape of the inner layer aggregated stranded wire becomes flat or uneven and tends to be non-perfect, and the skew of the coaxial wire assembly shifts and the transmission characteristics. Is prone to the problem of getting worse. However, according to the present invention, since the twisting directions of the inner layer aggregated stranded wire and the outer layer aggregated stranded wire are opposite to each other, it is difficult to form a non-perfect circle and the skew of the coaxial electric wire assembly is also difficult to shift. As a result, even if the multi-core communication cable is bent, the characteristics are unlikely to deteriorate, and the multi-core communication cable has improved flexibility.

In the multi-core communication cable according to the present invention, the twist pitch of the outer layer collective stranded wire is 2 to 4 times the twist pitch of the inner layer collective stranded wire. According to the present invention, by adopting the twist pitch relationship, it is possible to obtain a multi-core communication cable having improved flexibility because the characteristics are less likely to be deteriorated even if the multi-core communication cable is bent.

In the multi-core communication cable according to the present invention, the twist pitch of the outer layer collective stranded wire is 10 to 20 times the outer diameter of the multi-core communication cable.

In the multi-core communication cable according to the present invention, the twist pitch of the outer layer collective stranded wire is 50 to 100 times the outer diameter of the coaxial electric wire constituting the coaxial electric wire set.

According to the present invention, it is applied as a transmission cable for high-speed signal transmission compliant with the USB Type-C standard, and is a multi-core communication cable having a plurality of coaxial electric wires, which has a transmission characteristic of a high-speed digital signal of 10 Gbps or more. It is possible to provide a multi-core communication cable that can realize improvement, reduction in diameter, and improvement in flexibility. In particular, by reversing the twisting direction of the inner layer aggregated stranded wire and the twisting direction of the outer layer aggregated stranded wire and setting their twist pitches, the entire multi-core communication cable becomes flexible.

It is sectional drawing which shows an example of the multi-core communication cable which concerns on this invention. It is a perspective block diagram which shows the form of the coaxial electric wire which constitutes the multi-core communication cable which concerns on this invention. It is sectional drawing explaining the structural form of an insulator in detail. It is explanatory drawing of the twisted pair wire and the shield layer (metal resin tape) for twisted pair wire covering the twisted pair wire. It is sectional drawing of the metal resin tape. It is explanatory drawing which shows the bending test method of a multi-core communication cable.

An embodiment of the multi-core communication cable according to the present invention will be described with reference to the drawings. In addition, the present invention includes the invention of the same technical idea as the embodiment described below and the embodiment described in the drawings, and the technical scope of the present invention is limited to the description of the embodiment and the description of the drawings. Not a thing.

As shown in FIGS. 1 to 4, the multi-core communication cable 50 according to the present invention includes an inner layer collective stranded wire including a power supply line 11, a ground wire 12, and a twisted pair wire 13, and is covered with a presser winding tape 14 for an inner layer. 10 and four or more sets of coaxial electric wires 22 composed of two coaxial electric wires 21 and 21 are arranged on the outside of the inner layer collective twisted wire 10 and covered with a presser foot tape 24 for an outer layer. A multi-core communication cable 50 having an outer layer collective stranded wire 20, a shield layer 30 covering the outside of the outer layer collective stranded wire 20, and an outer sheath 40. The inner layer aggregate stranded wire 10 and the outer layer aggregate stranded wire 20 are characterized in that the twist directions are opposite to each other.

In this multi-core communication cable 50, since the twisting directions of the inner layer collective stranded wire 10 and the outer layer collective stranded wire 20 are opposite to each other, the non-perfect circle is less likely to occur and the skew of the coaxial electric wire assembly 22 is less likely to shift. As a result, even if the multi-core communication cable 50 is bent, the transmission characteristics are unlikely to deteriorate, and it is preferably applied as a transmission cable for high-speed signal transmission conforming to the USB Type-C standard. If the twisting directions of the inner layer collective stranded wire 10 and the outer layer aggregate stranded wire 20 are the same, the shape of the inner layer aggregate stranded wire 10 tends to be flat or uneven and becomes non-perfect, and the coaxial electric wire assembly 22 The problem that the skew shifts and the transmission characteristics deteriorate is likely to occur.

Hereinafter, each component will be described in detail.

[Outer layer aggregate stranded wire]
The outer layer aggregate stranded wire 20 is provided with an inner layer aggregate stranded wire 10 on the inside thereof, and a shield layer 30 and an outer sheath 40 on the outside thereof. The outer layer collective stranded wire 20 includes four or more sets of coaxial electric wires 22 including two coaxial electric wires 21 and 21. In the outer layer collective stranded wire 20, an insulating wire 25 functioning as a signal line may be arranged between the coaxial electric wires 21 and 21.

<Coaxial wire>
As shown in FIGS. 1 to 3, the coaxial electric wire 21 includes a central conductor 1, an insulator 2 continuous in the longitudinal direction on the outer periphery of the central conductor 1, and an outer conductor 3 provided on the outer periphery of the insulator 2. , It is composed of an outer cover 4 provided on the outer periphery of the outer conductor 3. The outer diameter of such a coaxial electric wire 21 is preferably in the range of 0.7 to 1.0 mm. The multi-core communication cable 50 according to the present invention includes four or more sets of coaxial electric wire sets 22 composed of two coaxial electric wires 21, and for example, in the example of FIG. 1, the embodiment consisting of four sets of coaxial electric wire sets 22 is shown. There is. The number of the coaxial electric wire sets 22 may be at least four sets or more, and the upper limit is not particularly limited, but may be about four sets to eight sets.

(Center conductor)
The central conductor 1 is composed of one strand extending in the longitudinal direction of the coaxial electric wire 21, or is composed of a plurality of strands twisted together. The type of the strand is not particularly limited as long as it is a good conductive metal, but it is a good conductive metal conductor such as a copper wire, a copper alloy wire, an aluminum wire, an aluminum alloy wire, or a copper-aluminum composite wire, or a surface thereof. A plating layer is preferably applied to the surface. From the viewpoint of high frequency, copper wire and copper alloy wire are particularly preferable. As the plating layer, a solder plating layer, a tin plating layer, a gold plating layer, a silver plating layer, a nickel plating layer and the like are preferable. The cross-sectional shape of the wire is not particularly limited, but the cross-sectional shape may be a circular or substantially circular wire rod, or may be a square shape.

The cross-sectional shape of the center conductor 1 is also not particularly limited, but may be circular (including an elliptical shape), rectangular, or the like. The outer diameter of the central conductor 1 is preferably as large as possible so that the electrical resistance (AC resistance, conductor resistance) becomes small, and for example, about 0.09 to 0.4 mm can be mentioned. An insulating film (not shown) may be provided on the surface of the center conductor 1 if necessary. The type and thickness of the insulating film are not particularly limited, but for example, those that decompose well at the time of soldering are preferable, and thermosetting polyurethane films and the like can be preferably mentioned.

(Insulator)
The insulator 2 is a low dielectric constant insulating layer continuously provided on the outer periphery of the central conductor 1 in the longitudinal direction. The insulator 2 may be a solid structure, a hollow structure, or a foamed structure. The hollow structure shown in FIGS. 2B and 3 is composed of an inner annular portion 2B, an outer annular portion 2C, and a connecting portion 2D connecting them, and has a gap portion 2A continuous in the longitudinal direction. Have. The gap portion 2A is continuously provided in the insulator 2, but its form may be round or rectangular, and is not particularly limited. In particular, in the insulator 2 composed of a hollow structure composed of an inner annular portion 2B, an outer annular portion 2C and a connecting portion 2D connecting them, the gap portion 2A is an inner annular portion 2B, an outer annular portion 2C and a connecting portion 2D. It has a cross-sectional shape surrounded by. Such a hollow structure is not easily deformed by stress applied at the time of bending, and can stabilize high frequency characteristics.

The material of the insulator 2 is not particularly limited, but a fluorine-based resin having a smaller dielectric constant than a polyolefin resin such as polyethylene, for example, a fluorine-based resin having a low dielectric constant and a low friction coefficient such as PFA, ETFE, and FEP is preferable and good. It can show good flexibility as well as high frequency transmission characteristics. In particular, since the insulator is formed with a low coefficient of friction, the friction with the thin metal wire provided on it is low, and the slight displacement of the thin metal wire that exhibits flexibility during bending is also low friction resistance. It is done with. As a result, the deviation can be easily returned and stable shield characteristics can be ensured. The material of the insulator 2 may contain a colorant.

When the insulator 2 has a hollow structure or a foamed structure, the material density of the insulator 2 is reduced, which has an additional effect that the insulator 2 can be softened, and the dielectric constant can be further reduced. For example, in the case of a hollow structure or a foamed structure having a hollow ratio of 40%, the dielectric constant can be reduced from about 2.1 to about 1.6. Therefore, when the dielectric constant of the insulator 2 is the same, the outer diameter of the insulator 2 can be reduced, and the diameter can be reduced to increase the flexibility. For example, in order to make the characteristic impedance of AWG 29 (0.287 mm) 50 Ω, the outer diameter needs to be about 0.9 mm in the solid structure, but by making it a hollow structure or a foamed structure, the outer diameter can be reduced to 0. The diameter can be reduced to 83 mm, and the outer diameter can be reduced by about 7%. By reducing the dielectric constant in this way, the diameter of the coaxial electric wire 21 can be reduced by, for example, about 7%.

The method for forming the insulator 2 is not particularly limited, but any of the solid structure, the hollow structure, and the foamed structure can be easily formed by extrusion. The insulator 2 can be formed by extruding a resin on the outer circumference of a central conductor 1 traveling on an extrusion die. The thickness of each of the inner annular portion 2B, the outer annular portion 2C, and the connecting portion 2D is not particularly limited, but is, for example, in the range of about 0.01 mm to 0.05 mm, and the outer diameter of the formed insulator 2 is determined. For example, it is in the range of about 0.5 to 1.0 mm. The porosity of the void portion 2A is preferably in the range of 20% to 60% with respect to the area of the entire dielectric layer (entire hollow structure).

(Outer conductor)
The outer conductor 3 is provided on the outer periphery of the insulator 2. The outer conductor 3 is provided separately from the shield layer 30 that covers the entire surface, which will be described later. The outer conductor 3 is formed by horizontally winding a thin metal wire. The thickness of the outer conductor 3 varies depending on the wire diameter and the number of twists of the thin metal wire used, and is not particularly limited.

The thin metal wire is not particularly limited as long as it is a finely conductive metal wire provided on the outer periphery of the dielectric layer (insulator 2) as an outer conductor of the coaxial electric wire. For example, various fine metal wires typified by tin-plated copper wire and the like can be preferably used. The diameter of the thin metal wire is also not particularly limited, but is preferably within the range of 1/10 to 1/20 of the outer diameter of the insulator 2. The winding pitch when the thin metal wire is wound horizontally varies depending on the outer diameter of the insulator 2, but is not particularly limited.

(Outer body)
The outer cover 4 is provided on the outer periphery of the outer conductor 3, and the material thereof is not particularly limited as long as it has an insulating property. A resin tape provided with a fusion layer on one side may be spirally wound, or a resin may be extruded and provided. As the constituent resin of the outer cover 4, various resins applied to the insulator 2 can be used in the case of resin extrusion, and for example, a fluororesin such as PFA, ETFE, or FEP may be used. , Vinyl chloride resin, polyolefin resin such as polyethylene, or polyester resin such as polyethylene terephthalate. The thickness of the outer cover 4 can be in the range of, for example, about 0.1 to 1.0 mm.

When a resin tape is used, it is possible to prevent the outer conductor 3 (horizontal winding of a thin metal wire) from being displaced by fusing it with the outer conductor 3. When a resin tape with a fusing layer is used, the side of the fusing layer is set to the side of the outer conductor 3 and the tape is wound horizontally. Examples of the material of the resin tape include polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyamide (PA), polyimide (PI), polyphenylene sulfide (PPS), and ethylene-ethylene tetrafluoride copolymer (ETFE). , Polyethylene tetrafluoride-propylene hexafluoride copolymer (FEP), fluorinated resin copolymer (perfluoroalkoxy alkane resin: PFA), polyether ether ketone (PEEK), and the like. The thickness of the resin tape is not particularly limited as long as it can secure the required dielectric strength, but can be about 0.004 to 0.01 mm. The fusion layer is provided on one side of the resin tape, and examples of the material thereof include thermosetting resins such as polyurethane resin, polyester resin, and polyesterimide resin. The thickness of the fused layer is also not particularly limited, but can be about 0.001 mm.

The resin tape may be one or two. When the outer cover 4 is composed of one resin tape, the resin tape is preferably a resin tape 4a with a cohesive layer. On the other hand, when the outer cover 4 is composed of two resin tapes, it is composed of a first resin tape 4a with a fusion layer and a second resin tape 4b not including the fusion layer. Is preferable. The resin tape (first resin tape) 4a with a fusion layer is horizontally wound with the fusion layer on the outer conductor side, and the outer conductor 3 and the first resin tape 4a are wound through the fusion layer. And glue. Due to this adhesion, even when an external force is applied to bend the metal wire, the fine metal wire does not shift and the characteristics are unlikely to deteriorate. Since the second resin tape 4b and the first resin tape 4a are not adhered to each other, a gap can be caused between the first resin tape 4a and the second resin tape 4b at the time of bending. Stress concentration is less likely to occur, disconnection is less likely to occur, and flexibility can be exhibited.

The horizontal winding pitch of these resin tapes is preferably in the range of 1/5 to 1/2 of the horizontal winding pitch of the fine metal wire. By doing so, the resin tape can be wound without gaps. The horizontal winding direction of the resin tape may be the same as the horizontal winding direction of the above-mentioned thin metal wire or the reverse winding direction, but the reverse direction is preferable. When two resin tapes are used, the first resin tape 4a and the second resin tape 4b may be horizontally wound in the same direction or horizontally wound in opposite directions. The tape width is arbitrarily selected depending on the winding pitch, ease of winding, and the like, and can be, for example, about 3 to 10 mm. The thickness of the resin tape is not particularly limited.

The fusion layer is provided on one side of the resin tape. The material of the fusion layer is a resin composition mainly composed of a thermoplastic resin, and preferably has a property of being able to adhere by causing a crosslinking reaction at a specific temperature or higher. Due to these properties, a resin tape with a fusion layer is provided by horizontally winding the resin tape with the fusion layer on the outer conductor side, and at that time or after that, it is heated to a specific temperature or higher to cause a cross-linking reaction to cause the outer conductor 3 Adhere to. Examples of the material of the fused layer include thermosetting resins such as polyurethane resin, polyester resin, and polyesterimide resin. Of these, polyurethane resin and polyester resin are preferable. The resin composition for forming the fusion layer for forming the fusion layer contains a cross-linking agent and a solvent. In addition, various additives are included as needed. The cross-linking agents, solvents and additives thereof are not particularly limited, and various cross-linking agents, solvents and additives according to the types of polyurethane resin, polyester resin, polyesterimide resin and the like and their required characteristics are used as needed. .. The thickness of the fused layer is also not particularly limited.

<Other lines>
As a configuration other than the above, the outer layer collective stranded wire 20 may optionally include an insulating wire 25 that functions as a signal line, a ground wire that functions as a ground wire (not shown), and the like. When the insulating wire 25 is included, it is preferably arranged concentrically so as to be in contact with the outer layer presser winding tape 24 as shown in FIG. 1, and may be provided between the coaxial electric wire sets 22 (FIG. FIG. 1) It may be provided between the coaxial electric wires 21 one by one (not shown). The insulating wire 25 is not particularly limited as long as it is composed of a metal conductor having good conductivity and an insulating layer provided on the outer periphery thereof. The material of the metal conductor is not particularly limited, and examples thereof can be mentioned as illustrated in the center conductor 1 described above. The material of the insulating layer is not particularly limited, but any resin material used for a general insulated wire may be used.

<Twisting direction and twisting pitch>
As shown in FIG. 1, the outer layer collective stranded wire 20 has the coaxial wire assembly 22 described above arranged as a single layer on the outer peripheral circumference of the inner layer aggregate stranded wire 10. The twisting direction of the outer layer collective stranded wire 20 is opposite to the twist direction of the inner layer collective stranded wire 10. By twisting in the opposite direction, the outer layer collective stranded wire 20 is less likely to be non-perfect, and the skew of the coaxial wire assembly 22 is less likely to shift. As a result, even if the multi-core communication cable 50 is bent, the characteristics are unlikely to deteriorate, and the multi-core communication cable 50 has improved flexibility. Such a multi-core communication cable 50 is preferably applied as a transmission cable for high-speed signal transmission conforming to the USB Type-C standard. On the other hand, if the twisting directions of the inner layer collective stranded wire 10 and the outer layer collective stranded wire 20 are the same, the skew of the coaxial electric wire assembly 22 shifts and the transmission characteristics deteriorate. The reason is that the shape of the inner layer collective stranded wire 10 tends to be flat or uneven and becomes non-perfect.

The twist pitch of the outer layer aggregate stranded wire 20 is preferably 2 to 4 times the twist pitch of the inner layer aggregate stranded wire 10 in relation to the twist pitch of the inner layer aggregate stranded wire 10. By doing so, even if the multi-core communication cable 50 is bent, the deterioration of the characteristics is less likely to occur, and it can be said that the flexibility is further improved. Specifically, when the twist pitch of the inner layer aggregate stranded wire 10 is in the range of 25 to 30 mm, the outer layer aggregate stranded wire 20 is preferably 50 to 120 mm, which is 2 to 4 times that of the inner layer aggregate stranded wire 10.

The twist pitch of the outer layer collective stranded wire 20 is preferably 10 to 20 times the outer diameter of the multi-core communication cable 50 in relation to the outer diameter of the multi-core communication cable 50. By doing so, even if the multi-core communication cable 50 is bent, the deterioration of the characteristics is less likely to occur, and it can be said that the flexibility is further improved. Specifically, when the outer diameter of the multi-core communication cable 50 is in the range of 4.5 to 5.0 mm, the outer layer collective stranded wire 20 is preferably 45 to 100 mm, which is 10 to 20 times that of the outer diameter.

The twist pitch of the outer layer collective stranded wire 20 is preferably 70 to 100 times the outer diameter of the coaxial electric wire 21 in relation to the outer diameter of the coaxial electric wire 21 constituting the coaxial electric wire assembly 22. By doing so, even if the multi-core communication cable 50 is bent, the deterioration of the characteristics is less likely to occur, and it can be said that the flexibility is further improved. Specifically, when the outer diameter of the coaxial electric wire 21 is in the range of 0.7 to 1.0 mm, the outer layer collective stranded wire 20 is preferably 49 to 100 mm, which is 70 to 100 times that of the outer diameter.

As described above, the twist pitch of the outer layer collective stranded wire 20 is related to the twist pitch of the inner layer collective stranded wire 10, the relationship with the outer diameter of the multi-core communication cable 50, and the outside of the coaxial electric wire 21 constituting the coaxial electric wire assembly 22. The flexibility of the multi-core communication cable 50 can be improved by setting the relationship with the diameter, whichever is one or more.

<Presser winding tape for outer layer>
The outer layer presser foot tape 24 is provided so as to cover and bundle two or more coaxial electric wire sets 22. The outer layer presser foot tape 24 is not particularly limited as long as it can hold the plurality of coaxial electric wire sets 22 so as not to come apart, but polyester tape, paper tape and the like can be mentioned, and Japanese paper tape is particularly preferable. be able to. The thickness of the outer layer presser winding tape 24 is also not particularly limited, and is preferably in the range of 0.003 to 0.01 mm. The tape width is arbitrarily selected depending on the winding pitch and the like. The outer layer presser winding tape 24 acts to hold the insulating wires 25 and the like together with the coaxial electric wire assembly 22 together. The outer layer collective stranded wire 20 can be bundled by the outer layer presser winding tape 24.

[Inner layer aggregate stranded wire]
The inner layer collective twisted wire 10 includes a power supply wire 11, a ground wire 12, and a twisted pair wire 13. The power supply line 11 is a line that conducts electric power, and is not particularly limited as long as it is composed of a metal conductor having good conductivity and an insulating layer provided on the outer periphery thereof. The material of the metal conductor is not particularly limited, and examples thereof can be mentioned as illustrated in the center conductor 1 described above. The material of the insulating layer is not particularly limited, but any resin material used for a general insulated wire may be used. For example, polyurethane, polyesterimide, polyamideimide, polyimide, polyester, polyphenylsulfide (PPS), fluororesin such as ETFE and FEP, and the like can be mentioned. In the example of FIG. 1, a set of two power supply lines 11 is illustrated. The ground wire 12 is wired together with the power supply line 11, and is not particularly limited as long as it is composed of a metal conductor having good conductivity and an insulating layer provided on the outer periphery thereof. They can be made of the same material as the power line. In the example of FIG. 1, a set of two ground wires 12 is illustrated. The twist pitch of the inner layer collective stranded wire 10 is preferably in the range of 10 to 40 mm.

(Twisted pair)
The twisted pair wire 13 acts as a signal line. Similar to the insulating wire 25, the twisted pair wire 13 is particularly composed of two insulating wires 13a and 13b composed of a metal conductor having good conductivity and an insulating layer provided on the outer periphery thereof. Not limited. The material of the metal conductor constituting each of the insulated wires 13a and 13b is not particularly limited, and examples of the central conductor 1 described above can be mentioned. The material of the insulating layer is not particularly limited, and any resin material used for a general insulated electric wire may be used.

(Shield layer for twisted pair)
As shown in FIG. 4, the twisted pair wire shield layer 16 is provided on the outer periphery of the twisted pair wire 13 so as to cover the twisted pair wire 13. By providing the twisted pair shield layer 16, the metal foil, metal braid, or horizontal winding shield that covers the entire inner layer collective stranded wire becomes unnecessary as in the conventional case. As a result, the flexibility of the multi-core communication cable 50 can be improved and the diameter can be reduced, and even if the cable is bent, the characteristics are less likely to deteriorate.

It is preferable to use the metal resin tape 16A shown in FIG. 5 as the twisted pair shield layer 16. Since the metal resin tape 16A is thin, the shielding characteristics and flexibility can be improved. Specifically, as shown in FIG. 4, the twisted pair wire shield layer 16 is horizontally wound so as to have an overlapping portion 17 in which a part of the metal layer 16a of the metal resin tape 16A is overlapped with the metal layer 16a inside. Shielding property and flexibility can be ensured by having the metal layer 16a of the metal resin tape 16A inside and winding it sideways without adhering it in a manner having the overlapping portion 17.

As shown in FIG. 5, the metal resin tape 16A is composed of at least a base material 16b and a metal layer 16a provided on the outermost surface of one surface of the base material 16b. The terms "at least" and "outermost surface" mean that another layer (for example, a primer layer or an adhesive layer) may be optionally provided between the base material 16b and the metal layer 16a. ing. In the present application, the fusion layer and the adhesive layer are not provided on the outermost surface (the surface of the base material or the surface of the metal layer) of the metal resin tape 16A.

The base material 16b is not particularly limited, but a polyester film such as polyethylene terephthalate or polyethylene naphthalate can be preferably used. The thickness of the base material 16b is arbitrarily selected from those in the range of, for example, about 2 to 20 μm. As the metal layer 16a, a copper layer, an aluminum layer and the like can be preferably mentioned. The metal layer 16a is a metal foil formed on the base material 16b by vapor deposition or plating, or a metal foil bonded via an adhesive layer (for example, a polyester-based thermoplastic adhesive resin) provided as needed. Etc. can be preferably mentioned. The thickness of the metal layer 16a is not particularly limited and varies depending on the forming means, but the one formed by vapor deposition or plating can be arbitrarily selected from the range of about 2 to 8 μm, and the metal foil is bonded. The one can be arbitrarily selected from the range of about 6 to 16 μm.

The metal resin tape 16A is horizontally wound having the overlapping portion 17 shown in FIG. The size of the overlapping portion 17 is preferably 0.5 to 5 mm for the reason of shielding. The horizontal winding pitch can be preferably selected in the range of 1 to 10 mm in consideration of the wire diameter of the twisted pair wire 13 and the drain wire 15 which may be provided as needed. The width of the metal resin tape 16A is not particularly limited, but is not particularly limited as long as it has overlapping portions 17 having predetermined dimensions and can cover the twisted pair wire 13.

(Drain wire)
The drain wire 15 may be arbitrarily provided and may be covered with the twisted pair wire shield layer 16 together with the twisted pair wire 13 as shown in FIGS. 1 and 4 (B). The drain wire 15 can enhance the flexibility and workability of the twisted pair wire 13 covered with the twisted pair wire shield layer 16 in addition to the original functions of a power supply return function and a grounding function. The configuration of the drain wire 15 is not particularly limited as long as it is composed of a metal conductor having good conductivity and an insulating layer provided on the outer periphery thereof, similarly to the insulating wire 25. The material of the metal conductor is not particularly limited, and examples thereof can be mentioned as illustrated in the center conductor 1 described above. The material of the insulating layer is not particularly limited, but any resin material used for a general insulated wire may be used.

<Presser winding tape for inner layer>
The power supply line 11, the ground wire 12, and the twisted pair wire 13 are preferably covered with the inner layer presser winding tape 14. The inner layer presser winding tape 14 is not particularly limited as long as it can hold the power supply line 11, the ground wire 12, and the twisted pair wire 13 so as not to come apart, but polyester tape or the like can be preferably mentioned, for example. it can. The thickness is not particularly limited, and is preferably in the range of 0.003 to 0.01 mm. The outer diameter of the inner layer collective stranded wire 10 after being wound with the inner layer presser winding tape 14 is arbitrarily selected according to its role and application, and is not particularly limited. The tape width is arbitrarily selected depending on the winding pitch and the like, and is not particularly limited.

[Shield layer]
The shield layer 30 covers the outside of the outer layer collective stranded wire 20. The configuration of the shield layer 30 is not particularly limited, and a single or double horizontal winding of a thin metal wire can be preferably mentioned. In the case of double horizontal winding, the horizontal winding of the first layer and the horizontal winding of the second layer may be wound one layer at a time in the same direction, or one layer at a time in different directions. It may be rolled up. By winding it horizontally in the opposite direction, it is possible to prevent disconnection from occurring. The shield layer 30 can be provided by arbitrarily selecting and providing a thin metal wire similar to the thin metal wire exemplified in the central conductor 1. The thickness of the shield layer 30 may be such that the shield performance can be exhibited, and is not particularly limited, but is, for example, in the range of about 0.05 to 0.30 mm.

[Coat sheath]
The outer sheath 40 covers the outside of the shield layer 30. The outer sheath 40 may be extruded from resin or wrapped with tape. The material of the resin-extruded outer sheath 40 is not particularly limited as long as it has an insulating property, as in the case of the outer body 4. For example, various generally applied substances can be used, for example, a fluororesin such as ETFE, a vinyl chloride resin, or a polyolefin resin such as polyethylene may be used. Alternatively, it may be a polyester resin such as polyethylene terephthalate. The thickness of the outer sheath 40 extruded from the resin can be, for example, in the range of about 0.5 to 1.5 mm. By providing such a resin extruded sheath 7, the finished outer diameter of the multi-core communication cable 50 is not particularly limited.

Instead of the extruded outer sheath 40, a tape-wrapped outer sheath 40 may be used. As the tape-wrapped outer sheath 40, various types used as insulating tapes for coaxial electric wires can be arbitrarily selected and used within a range satisfying necessary characteristics.

[Multi-core communication cable]
The multi-core communication cable 50 preferably has an outer diameter in the range of 3.8 to 5.0 mm. The multi-core communication cable 50 can be preferably applied as a transmission cable for high-speed signal transmission conforming to the USB Type-C standard. In particular, since the braided or horizontally wound shield layer is not provided on the outer periphery of the inner layer aggregated stranded wire 10 including the power supply line 11, the ground wire 12, and the twisted pair wire 13 arranged inside the outer layer aggregated stranded wire 20. The multi-core communication cable 50 has good transmission characteristics at the time of bending without hindering flexibility and diameter reduction. Therefore, it is possible to improve the transmission characteristics of a high-speed digital signal of 10 Gbps or more, reduce the diameter, and improve the flexibility.

Hereinafter, the present invention will be described in more detail with reference to examples. The present invention is not limited to the following examples.

[Example 1]
(Coaxial wire)
First, the coaxial electric wire 21 having the form shown in FIG. 2 (A) was produced. For each coaxial electric wire 21, AWG30 (outer diameter of about 0.3 mm) obtained by twisting seven tin-plated annealed copper wires having a diameter of 0.10 mm was used as the central conductor 1. Next, a PFA resin (manufactured by DuPont) is extruded on the outer periphery of the central conductor 1 with a die nipple for a hollow structure at 350 ° C., and the gap portion 2A becomes an inner annular portion 2B, an outer annular portion 2C and a connecting portion 2D. An insulator 2 made of a hollow structure shown in FIG. 2B having a cross-sectional shape surrounded by is formed. In the insulator 2, the thickness of the inner annular portion 2B is 0.05 mm, the thickness of the outer annular portion 2C is 0.05 mm, the thickness of the connecting portion 2D is 0.05 mm, and the outer diameter of the entire insulator is It was 0.71 mm, and the porosity of the void portion 2A was 29% with respect to the total area of the insulator. As shown in FIG. 3, the shape of the gap 2A was substantially trapezoidal. Next, the outer conductor 3 was formed on the insulator 2. The outer conductor 3 was wound left at a pitch of 14 mm using 43 tin-plated annealed copper wires (thin metal wires, abbreviated as TCW) having a diameter of 0.05 mm. The outer diameter after providing the outer conductor 3 was 0.81 mm. On top of that, an outer cover 4 made of a resin tape was provided. The resin tape 4a is a tape having a width of 3 mm in which a bonding layer having a thickness of 0.008 mm is provided on a PET substrate having a thickness of 0.004 mm, and the bonding layer is on the outer conductor 3 side at a pitch of 4 mm. I wound it to the right. The outer diameter after the outer cover 4 made of the resin tape 4a was provided was 0.85 mm.

(Inner layer aggregate stranded wire)
A power supply line 11, a ground wire 12, and a twisted pair wire 13 were prepared as the inner layer aggregate twisted wire 10. For the twisted pair wire 13, two wires having a diameter of 0.56 mm made of AWG32 (outer diameter of about 0.24 mm) obtained by twisting seven tin-plated annealed copper wires having a diameter of 0.08 mm are prepared, twisted uniformly, and twisted. It was covered with a counterwire shield layer 16. The twisted pair shield layer 16 was wound horizontally with a metal resin tape 16A at a pitch of 10 mm so as to have an overlapping portion 17 of 0.8 mm. As the power supply line 11, two wires having a diameter of 0.66 mm made of AWG26 (outer diameter of about 0.5 mm) obtained by twisting 19 tin-plated annealed copper wires having a diameter of 0.10 mm were prepared. As the ground wire 12, two wires having a diameter of 0.44 mm made of AWG30 (outer diameter of about 0.3 mm) obtained by twisting seven tin-plated annealed copper wires having a diameter of 0.10 mm were prepared. The presser foot tape 14 was made of polyester and had a thickness of 0.012 mm and a width of 5.5 mm, and was wound with a pitch of 4 mm. In this way, the inner layer aggregate stranded wire 10 was produced.

(Outer layer collective stranded wire)
As the outer layer collective stranded wire 20, four sets of coaxial electric wire sets 22 in which the above coaxial electric wires 21 were set as a set were prepared, and arranged so as to form a single layer on the outer periphery of the inner layer collective stranded wire 10. Further, one insulated wire 25 functioning as a signal line was arranged between the coaxial electric wire sets 22. Each of the prepared wires was collectively twisted at a twist pitch of 71 mm. The twisting direction of the outer layer aggregated stranded wire 20 thus collectively twisted was set to be opposite to the twisting direction of the inner layer aggregated stranded wire 10 described above. Then, they were formed by covering them with the outer layer presser winding tape 24. The presser wound tape 24 is made of Japanese paper tape and has a thickness of 0.03 mm and a width of 15 mm and is wound with a pitch of 11 mm. In this way, the outer layer aggregate stranded wire 20 was produced.

(Shield layer and outer sheath)
The shield layer 30 and the outer sheath 40 were formed so as to cover the outer layer collective stranded wire 20. The shield layer 30 was right-handed using 105 tin-plated annealed copper wires having a diameter of 0.10 mm. The winding pitch was 40 mm. Then, a soft PVC having a thickness of 0.4 mm was extruded to provide an outer sheath 40. In this way, a multi-core communication cable 50 having a final outer diameter of 4.8 mm was obtained.

[Examples 2 to 6]
In the multi-core communication cable of Example 1, P1: the twist pitch of the outer layer collective stranded wire (mm), P2: the twist pitch of the inner layer collective stranded wire (mm), D1: the outer diameter of the coaxial electric wire (mm), D2: many. The outer diameter (mm) of the core communication cable was changed to the value shown in Table 1. A multi-core communication cable of Examples 2 to 6 was obtained in the same manner as in Example 1 except for the above.

[Comparative Example 1]
Unlike the first embodiment, the twisting direction of the inner layer aggregated stranded wire 10 and the twisting direction of the outer layer aggregated stranded wire 20 are the same. A multi-core communication cable of Comparative Example 1 was obtained in the same manner as in Example 1 except for the above.

[Comparative Examples 2 to 6]
Similar to Comparative Example 1, the twisting direction of the inner layer aggregated stranded wire 10 and the twisting direction of the outer layer aggregated stranded wire 20 were made the same. Further, P1: twist pitch of the outer layer collective stranded wire (mm), P2: twist pitch of the inner layer collective stranded wire (mm), D1: outer diameter of the coaxial electric wire (mm), D2: outer diameter of the multi-core communication cable (mm). ) Was changed to the value shown in Table 1 to obtain a multi-core communication cable of Comparative Examples 2 to 6.

[Bending resistance test]
FIG. 6 is an explanatory diagram showing a bending test method of the multi-core communication cable of the example and the comparative example. The measurement was performed with a U-shaped bend of R20 mm (four times the diameter of the multi-core communication cable) in the manner shown in FIG. 5 at the fixing portions 62, 62 of the fixing plates 61, 61 facing the multi-core communication cable having a length of 2 m. It was fixed so that it became a part. The opposing fixing plates 61 and 61 were moved relative to each other (± 50 mm) to bend the bent portion of the multi-core communication cable 50. The attenuation (dB / m) of the communication cable 50 after the bending test was measured with a network analyzer. It was evaluated whether or not the damping amount at the stage when the number of bendings reached 20000 times deteriorated to 90% as compared with the damping amount before the test. In Examples 1 to 6, no decrease in the damping amount was observed even when the number of bendings reached 20000. On the other hand, in Comparative Examples 3 and 6, a decrease in the damping amount was observed when the number of bendings reached 20000. Further, in Comparative Example 5, the value of the attenuation amount was unstable.

1 Center conductor 2 Insulator 2A Void part 2B Inner ring part 2C Outer ring part 2D Connecting part 3 Outer conductor 4 Outer body 4a First resin tape 4b Second resin tape 10 Inner layer collective stranded wire 11 Power line 12 Ground wire 13 Twisted pair wires 13a, 13b Insulated wires that make up the twisted pair wires 14 Inner layer presser winding tape 15 Drain wire 16 Twisted pair wire shield layer 16A Metal resin tape 16a Metal layer 16b Base material 17 Overlapping part 20 Outer layer collective stranded wire 21 Coaxial wire 22 Coaxial wire assembly 23 Ground wire 24 Twisted pair tape for outer layer 25 Insulated wire (signal line)
30 Shield layer 40 Outer sheath 50 Multi-core communication cable 61 Fixing plate 62 Fixing part

Claims (4)

An inner layer collective stranded wire including a power supply line, a ground wire and a twisted pair wire, and covered with a presser foot tape for the inner layer, and an inner layer collective stranded wire arranged in a circumferential shape on the outside of the inner layer aggregate stranded wire, and consisting of two coaxial wires 4 A multi-core communication cable including a set or more of coaxial electric wires and having an outer layer collective stranded wire covered with a presser foot tape for an outer layer, a shield layer covering the outside of the outer layer collective stranded wire, and an outer sheath. A multi-core communication cable characterized in that the twisted directions of the inner layer aggregated stranded wire and the outer layer aggregated stranded wire are opposite to each other. The multi-core communication cable according to claim 1, wherein the twist pitch of the outer layer aggregated stranded wire is 2 to 4 times the twist pitch of the inner layer aggregated stranded wire. The multi-core communication cable according to claim 1 or 2, wherein the twist pitch of the outer layer collective stranded wire is 10 to 20 times the outer diameter of the multi-core communication cable. The multi-core communication cable according to any one of claims 1 to 3, wherein the twist pitch of the outer layer collective stranded wire is 70 to 100 times the outer diameter of the coaxial electric wire constituting the coaxial electric wire set.

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