JP2020021703A - Multicore communication cable - Google Patents

Abstract

To provide a multicore communication cable capable of suitably transmitting high speed digital signal of 10 Gbps or more, hardly generating breakage or crack in an outside conductor and hardly reducing transmission characteristics even when bent, and having flexibility.SOLUTION: There is provided a multicore communication cable containing two or more pairs of coaxial wire pair consisting of two coaxial wires 1 and an outer coating sheath covering the two or more pairs of the coaxial wire pair. The coaxial wires 1 have a center conductor 11, an insulator 12, an outside conductor 13, and an outer coated body 14 in this order. The outside conductor 13 is constituted by a first outside conductor 13a by vertically attaching a first metal resin tape with a metal layer surface outside on the insulator 12, a second outside conductor 13b by horizontally winding thin metallic wire on the first outside conductor 13a, and a third outside conductor 13c by horizontally winding a second metal resin tape with the metal layer surface inside on the second outside conductor 13b.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a multi-core high-speed signal transmission cable having a plurality of coaxial wires, and more particularly, it can suitably transmit a high-speed digital signal of 10 Gbps or more, and does not easily deteriorate in characteristics even when bent. The present invention relates to a flexible multi-core communication cable.

  In recent years, communication cables typified by USB 3.1 and the like tend to be required to have a small diameter and flexibility in order to handle frequently used insertions and removals as the operating frequency increases. For example, in Japanese Patent Application Laid-Open No. H10-157,992, a high-speed digital signal of 10 Gbps or more can be suitably transmitted, and a multi-core twisted cable or a bent cable has been proposed. Even in such a case, a high-speed signal transmission cable is proposed in which the signal transmission speed is constant, the characteristics are not easily deteriorated, and the variation in the electrical length of each cable is small. This technology is a high-speed signal transmission cable comprising a coaxial line assembly, a shield layer provided on the outer periphery of the coaxial line assembly, and a sheath provided on the outermost layer. , A hollow core body, and an external conductor formed by vertically attaching a metal foil or a plastic tape provided with a metal layer to the outer periphery of the hollow core body.

  Patent Document 2 proposes a technique for providing a multi-core cable capable of suppressing crosstalk between a pair of coaxial wires. In this technique, two or more pairs of coaxial wires are configured in such a manner that two coaxial wires are in contact with each other and are arranged in parallel, and each coaxial wire is composed of a center conductor, an insulator, an outer conductor, and a jacket. I have. The outer conductor has an inner layer portion formed by horizontally winding a thin metal wire, and an outer layer portion formed by horizontally winding a metal resin tape around the inner layer portion. Is a direction opposite to the winding direction of the metal resin tape of the outer layer portion, and the angle of the winding direction of the metal resin tape with respect to the winding direction of the fine metal wire is 30 degrees or more and 90 degrees or less. The crosstalk between the coaxial wire pairs is set to −40 dB or less by including two or more pairs of coaxial wire pairs in which two coaxial wires are in contact with each other and arranged in parallel.

WO2013 / 069755 Japanese Patent Application Laid-Open No. 2006-207658

  Regarding the flexibility, small cracks or breaks in the outer conductor may reduce the flexibility. For example, in the cable of Patent Document 1, as an external conductor, a metal foil or a metal resin tape provided with a metal layer is vertically attached to the outer periphery of the hollow core body, and a braided wire is further provided on the outer periphery to form a double structure. Are listed. When the coaxial electric wire is bent to a small diameter, the surface to which the metal resin tape is attached is peeled and the vertical attachment structure is easily broken, and the distance between the outer conductor and the center conductor changes, resulting in phase fluctuation. And transmission characteristics may be degraded. In particular, when a differential signal is transmitted at a high speed, there is a problem that the signal transmission speed changes between two signals and transmission characteristics deteriorate.

  Further, the coaxial cable of Patent Document 2 has a double structure of an inner layer portion formed by horizontally winding a thin metal wire as an outer conductor and a metal resin tape wound horizontally around the inner layer portion. Things are listed. When the coaxial wire is bent to a small diameter, the horizontal winding structure of the metal resin tape also tends to collapse, the distance between the outer conductor and the center conductor changes, and phase fluctuations easily occur. May decrease.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to be able to suitably transmit a high-speed digital signal of 10 Gbps or more, and to prevent the outer conductor from being damaged or cracked even when bent. An object of the present invention is to provide a flexible multi-core communication cable that is hardly generated and transmission characteristics are hardly deteriorated.

The multi-core communication cable according to the present invention is a multi-core communication cable including two or more coaxial cable sets each including two coaxial cables, and covering the two or more coaxial cable sets with a sheath sheath, The coaxial wire has a center conductor, an insulator, an outer conductor, and a jacket in that order,
The outer conductor includes a first outer conductor formed by vertically attaching a first metal resin tape having a metal layer surface outside on the insulator, and a thin metal wire wound horizontally on the first outer conductor. It is characterized by comprising a second outer conductor and a third outer conductor formed by horizontally winding a second metal resin tape having a metal layer surface inside on the second outer conductor.

  According to this invention, since the first metal resin tape as the first external conductor is vertically attached on the insulator, the current flow path of the external conductor can be minimized. In addition, as the external conductor, a triple attachment of a first metal resin tape (first external conductor), a horizontal winding of a thin metal wire (second external conductor), and a horizontal winding of a second metal resin tape (third external conductor) are used. With the structure, the conductor cross-sectional area can be increased, and the insertion loss can be reduced. Further, since the second outer conductor is provided on the first outer conductor and the third outer conductor is provided on the second outer conductor, even when the first outer conductor is pressed down and the coaxial wire is bent to a small diameter. In addition, it is possible to prevent the first external conductor from collapsing or peeling as in the related art. As a result, even when it is bent to a small diameter, the distance between the outer conductor and the center conductor does not change, so that phase fluctuation hardly occurs, and it is possible to suppress a decrease in signal transmission characteristics (attenuation and skew). In particular, even when a differential signal is transmitted at a high speed, it is possible to suppress a change in signal transmission speed between two signals and to prevent a decrease in transmission characteristics. Further, even when bending stress is repeatedly applied, the outer conductor structure hardly causes breakage or cracking of the metal layer of the first outer conductor, and does not cause a change in dielectric constant due to the breakage or crack.

  In the multi-core communication cable according to the present invention, the diameter of the thin metal wire as the second outer conductor is 1/10 to 1/20 of the outer diameter of the insulator.

  ADVANTAGE OF THE INVENTION According to this invention, disconnection is hard to generate | occur | produce, maintaining a horizontal winding density and maintaining favorable high frequency transmission characteristics.

  In the multi-core communication cable according to the present invention, the thickness of the metal layer forming the first outer conductor and the third outer conductor is in a range of 2 to 8 μm, and the first outer conductor and the third outer conductor are formed. The thickness of the resin substrate to be formed is in the range of 2 to 20 μm.

  According to the present invention, since the thickness of the metal layer is within the above range, good shielding characteristics can be obtained.

  In the multi-core communication cable according to the present invention, the jacket is formed by horizontally winding the resin layer with the fusion layer with the fusion layer facing the external conductor, and the third external conductor and the resin tape. Are bonded through the fusion layer.

  According to the present invention, since the third outer conductor and the resin tape are bonded via the fusion layer, the third outer conductor does not shift in position, and a stable shield can be provided even when the third outer conductor is bent. Characteristics can be maintained.

  In the multi-core communication cable according to the present invention, the outer sheath has one or two or more press-winding tapes, a shield layer, and a resin extrusion layer in this order from the inside to the outside.

  ADVANTAGE OF THE INVENTION According to this invention, while being able to transmit a 10 Gbps or more high-speed digital signal suitably, even if it bends, damage and a crack are hard to generate | occur | produce in an outer conductor, and flexible multi-core communication which transmission characteristic does not fall easily is flexible. Cable can be provided.

It is a sectional view showing an example of the multi-core communication cable concerning the present invention. FIG. 1 is a perspective configuration diagram illustrating a form of a coaxial cable constituting a multi-core communication cable according to the present invention.

  An embodiment of a multi-core communication cable according to the present invention will be described with reference to the drawings. Note that the present invention includes an invention having the same technical idea as the embodiments described below and the embodiments described in the drawings, and the technical scope of the present invention is limited only to the description of the embodiments and the drawings. Not something.

[Multi-core communication cable]
As shown in FIGS. 1 and 2, the multi-core communication cable 10 according to the present invention includes two or more coaxial wire sets 2 each including two coaxial wires 1, 1 and two or more coaxial wire sets 2. Is covered with a sheath sheath 4. The coaxial electric wire 1 has a central conductor 11, an insulator 12, an outer conductor 13, and a jacket 14 in that order. The outer conductor 13 is composed of a first outer conductor 13a formed by vertically attaching a first metal resin tape having a metal layer surface on the insulator 12, and a thin metal wire wound horizontally on the first outer conductor 13a. And a third external conductor 13c formed by horizontally winding a second metal resin tape with the metal layer surface inside on the second external conductor 13b.

  In this multi-core communication cable 10, since the first metal resin tape as the first outer conductor 13a is vertically attached on the insulator 12, the current flow path of the outer conductor 13 can be minimized. Further, as the outer conductor 13, a first metal resin tape is vertically attached (first outer conductor 13 a), a thin metal wire is horizontally wound (second outer conductor 13 b), and a second metal resin tape is horizontally wound (third outer conductor 13 c). ), The conductor cross-sectional area can be increased, and the insertion loss can be reduced. Further, since the second outer conductor 13b is provided on the first outer conductor 13a and the third outer conductor 13c is provided on the second outer conductor 13b, the first outer conductor 13a is pressed down and the coaxial cable 1 is bent to a small diameter. Even in this case, the first outer conductor 13a can be prevented from collapsing or peeling as in the related art. As a result, even when it is bent to a small diameter, the distance between the outer conductor 13 and the center conductor 11 does not change, so that a phase change hardly occurs and a decrease in signal transmission characteristics (attenuation and skew) can be suppressed. . In particular, even when a differential signal is transmitted at a high speed, it is possible to suppress a change in signal transmission speed between two signals and to prevent a decrease in transmission characteristics. In addition, even if bending stress is repeatedly applied, the outer conductor structure hardly causes breakage or cracking of the metal layer of the first outer conductor 13a, and does not cause a change in dielectric constant due to the breakage or cracking.

  Hereinafter, each component will be described in detail.

<Coaxial cable>
As shown in FIGS. 1 and 2, the coaxial electric wire 1 includes a center conductor 11, an insulator 12 continuous in the longitudinal direction Y around the outer periphery of the center conductor 11, and an outer conductor 13 provided on the outer periphery of the insulator 12. And an outer casing 14 provided on the outer periphery of the outer conductor 13.

(Center conductor)
The center conductor 11 is configured by one strand extending in the longitudinal direction Y of the coaxial cable 1 or by twisting a plurality of strands. The type of the wire is not particularly limited as long as it is a good conductive metal, but a good conductive metal conductor such as a copper wire, a copper alloy wire, an aluminum wire, an aluminum alloy wire, a copper-aluminum composite wire, or a surface thereof. And those having a plating layer formed thereon. 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 element wire is not particularly limited, either, and the cross-sectional shape may be a circular or substantially circular wire, or may be a square shape.

  The cross-sectional shape of the center conductor 11 is not particularly limited, but may be circular (including an elliptical shape) or rectangular. It is desirable that the outer diameter of the center conductor 11 be as large as possible so as to reduce the electric resistance (AC resistance, conductor resistance), for example, about 0.09 to 0.4 mm. An insulating film (not shown) may be provided on the surface of the center conductor 11 as necessary. Although the type and thickness of the insulating film are not particularly limited, for example, a material that decomposes well during soldering is preferable, and a thermosetting polyurethane film and the like can be preferably used.

(Insulator)
The insulator 12 is a low dielectric constant insulating layer provided continuously on the outer periphery of the center conductor 11 in the longitudinal direction Y. The material of the insulator 12 is not particularly limited. For example, a fluorine-based resin having a low dielectric constant such as PFA, ETFE, or FEP is preferable, and can exhibit good high-frequency transmission characteristics. The material of the insulator 12 may contain a coloring agent. The method for forming the insulator 12 is not particularly limited, and examples thereof include extrusion and coating. The structure of the insulator 12 may be a solid structure, a hollow structure, or a foam structure. Since the hollow structure and the foamed structure have voids inside the structure, the dielectric constant can be further reduced. The thickness of the insulator 12 is also not particularly limited, but is preferably in the range of about 0.2 to 0.5 mm. In addition, the hollow structure can exemplify a cross section or the like in which the gap is surrounded by an inner annular portion, an outer annular portion, and a connecting portion.

(Outer conductor)
The outer conductor 13 is provided on the outer periphery of the insulator 12. The outer conductor 13 is provided so as to be distinguished from a shield layer 6 that covers the whole, which will be described later. The outer conductor 13 includes a first outer conductor 13a formed by vertically attaching a first metal resin tape having an outer surface of a metal layer on an insulator 12, and a thin metal wire wound horizontally on the first outer conductor 13a. And a third external conductor 13c formed by horizontally winding a second metal resin tape having a metal layer surface inside on the second external conductor 13b. I have. The external conductor 13 having such a triple structure has a large conductor cross-sectional area and can reduce insertion loss. In the present application, reference numeral 13a is also used for the first metal resin tape constituting the first external conductor 13a, reference numeral 13b is also used for the thin metal wire constituting the second external conductor 13b, and the third external conductor 13c is provided. Reference numeral 13c is also used for the second metal resin tape to be constituted.

  The first outer conductor 13a is formed by vertically attaching a first metal resin tape on the insulator 12 (also referred to as the periphery of the insulator 12). The longitudinal attachment is performed with the metal layer surface constituting the first metal resin tape facing outward (toward the second external conductor 13b provided thereafter). With the first outer conductor 13a, the current flow path of the outer conductor 13 can be minimized. The first metal resin tape has a metal layer provided on a resin base material. The resin substrate is not particularly limited, but a polyester film such as polyethylene terephthalate or polyethylene naphthalate can be preferably used. The thickness of the resin substrate is arbitrarily selected, for example, in the range of about 2 to 20 μm. Preferred examples of the metal layer include a copper layer and an aluminum layer. The metal layer is preferably a film formed by vapor deposition or plating on a resin substrate, or a metal foil bonded via an adhesive layer (for example, a polyester-based thermoplastic adhesive resin). The thickness of the metal layer is not particularly limited, and varies depending on the forming means. However, a film formed by vapor deposition or plating can be arbitrarily selected from a range of about 2 to 8 μm, and a metal foil is bonded. Can be arbitrarily selected from the range of about 6 to 16 μm.

  As shown in FIG. 2, the longitudinal attachment is such that the resin base side of the first metal resin tape is the insulator 12 side and the metal layer surface side is the outside (the second external conductor side), and the longitudinal direction Y is partially overlapped. And wrap it around it. Although the width of the first metal resin tape is not particularly limited, it is set by the outer peripheral length of the insulator 12 and the dimension of the overlapping portion. .

  A second external conductor 13b is provided on the first external conductor 13a, and a third external conductor 13c is provided on the second external conductor 13b. By doing so, even if the first outer conductor 13a is pressed by the second outer conductor 13b and the third outer conductor 13c and the coaxial cable 1 is bent to a small diameter, the first outer conductor 13a is Can be prevented from collapsing or peeling off. As a result, even when it is bent to a small diameter, the distance between the outer conductor 13 and the center conductor 11 does not change, so that a phase change hardly occurs and a decrease in signal transmission characteristics (attenuation and skew) can be suppressed. . In particular, even when a differential signal is transmitted at a high speed, it is possible to suppress a change in signal transmission speed between two signals and to prevent a decrease in transmission characteristics. Furthermore, even when bending stress is repeatedly applied, the outer conductor structure hardly causes breakage or cracking of the metal layer of the first outer conductor 13a, and does not cause a change in dielectric constant due to the breakage or cracking.

  The second outer conductor 13b is formed by horizontally winding a thin metal wire on the first outer conductor 13a. The thin metal wire is not particularly limited as long as it is a highly conductive thin metal wire that can be provided on the outer periphery of the first outer conductor 13a (longitudinally attached to the first metal resin tape) as the second outer conductor 13b of the coaxial cable 1. For example, various thin metal wires represented by tin-plated copper wires and the like can be preferably used. The diameter of the thin metal wire is not particularly limited, either, but may be, for example, in the range of about 0.04 to 0.1 mm. The number of the fine metal wires is arbitrarily selected depending on the outer diameter of the first outer conductor 13a, the expected outer diameter of the coaxial electric wire 1, and the like. Forty-three thin metal wires can be wound horizontally to form the second outer conductor 13b.

  The horizontal winding pitch P1 when the thin metal wire is horizontally wound is not particularly limited, and may be, for example, about 14 mm as in the example described later.

  The third outer conductor 13c is formed by horizontally winding a second metal resin tape on the second outer conductor 13b. The second metal resin tape has a metal layer provided on a resin base material, and may be the same as or different from the first metal resin tape used for the first outer conductor 13a. Is also good. The material, thickness, and the like of the resin base material and the metal layer can be arbitrarily selected from those described in the description section of the first metal resin tape.

  The second metal resin tape is horizontally wound at a horizontal winding pitch P2 of 4 to 10 mm. When performing the horizontal winding at the horizontal winding pitch P2, the tape width is selected so that the wrap is 1/5 to 1/2. It is preferable that the horizontal winding pitch P2 and the tape width for horizontal winding with the wrap are arbitrarily selected and used. The horizontal winding of the second metal resin tape is performed in a state where the metal layer faces the thin metal wire so that the metal layer directly contacts the thin metal wire of the second outer conductor 13b. As a result, the thin metal wire and the metal layer can be electrically connected, and the thin metal wire is also in direct contact with the metal layer of the first metal resin tape. And a stable shield characteristic can be secured. The metal layer of the second metal resin tape is directly contacted and arranged on the fine metal wire without causing a gap between the metal layers of the second metal resin tape by arranging the metal layer of the second metal resin tape so as to be horizontally wound under the wrap with the horizontal winding pitch P2. be able to. As a result, even if the thin metal wire exhibiting the flexibility at the time of bending moves slightly, the electrical conduction can be further stabilized, and stable shield characteristics can be secured.

  The horizontal winding pitch P2 of the second metal resin tape is preferably in the range of 1/5 to 1/2 of the horizontal winding pitch P1 of the fine metal wire. By doing so, the second metal resin tape can be wound without any gaps, and the fine metal wires can be suppressed. The horizontal winding direction of the second metal resin tape may be the same as the horizontal winding direction of the above-described thin metal wire, or may be the reverse winding direction, but the reverse direction is preferable. The tape width is arbitrarily selected depending on the winding pitch, ease of winding, and the like, and may be, for example, about 3 to 10 mm as in the examples described later.

  The second metal resin tape is adhered to a resin tape with a fusion layer described later via a fusion layer 14b. As a result, the thin metal wires located under the second metal resin tape during the terminal strip are not separated.

  The total thickness of the first outer conductor 13a, the second outer conductor 13b, and the third outer conductor 13c constituting the triple-structured outer conductor 13 is determined by the wire diameter and the number of twists of the thin metal wires used, the first metal resin tape, and the like. It is not particularly limited because it varies depending on the thickness of the metal layer of the second metal resin tape, the thickness of the resin base material, and the like. With such a structure of the outer conductor 13, a stable outer conductor structure can be obtained, flexibility is improved, and stress concentration is improved, as compared with a conventional external conductor having a vertically attached structure or a horizontally wound structure of a metal tape. It is hard to get up and it is hard to break.

(Coat body)
The outer cover 14 is provided on the outer periphery of the outer conductor 13. The outer cover 14 is formed by horizontally winding the resin tape 14a having the insulating fusion layer 14b with the fusion layer 14b side being the outer conductor side. Examples of the material of the resin tape 14a constituting the jacket 14 include polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyamide (PA), polyimide (PI), polyphenylene sulfide (PPS), and ethylene-tetrafluoroethylene. Ethylene copolymer (ETFE), ethylene tetrafluoride-propylene hexafluoride copolymer (FEP), fluorinated resin copolymer (perfluoroalkoxy fluororesin: PFA), polyetheretherketone (PEEK), etc. Can be mentioned. In terms of hardness and elongation, polyethylene terephthalate (PET), polyethylene naphthalate (PEN) and the like are preferable. These resin tapes 14a usually have a single layer, but may have two or more layers according to the purpose. The thickness of the resin tape 14a is not particularly limited as long as it is a thickness that can secure a necessary dielectric strength voltage, but can be set to about 0.004 mm as in the embodiment described later. The resin tape 14a may be colored. Coloring can be provided by including a colorant in the resin tape 14a or applying or printing the colorant on the resin tape 14a. By coloring the resin tape 14a, different colors can be given to the obtained coaxial wires 1, and the colors can identify the coaxial wires 1 having respective roles.

  The fusion layer 14b is provided on one side of the resin tape 14a. The material of the fusion layer 14b is a resin composition mainly composed of a thermoplastic resin, and preferably has a property that a cross-linking reaction takes place at a specific temperature or higher to enable adhesion. By having such a property, a resin tape with a fusion layer is provided in a horizontal winding with the fusion layer 14b facing the outer conductor, and at that time or thereafter, heated to a specific temperature or higher to cause a crosslinking reaction to cause the outer conductor 13 is adhered. By doing so, the resin tape with the fusion layer adheres and fixes the second metal resin tape 13c located thereunder via the fusion layer 14b, so that the displacement of the metal layer can be prevented. As a result, stable shield characteristics can be maintained even when bending occurs, and the thin metal wires located under the second metal resin tape 13c during terminal strip can be prevented from coming apart. Good workability and no risk of short circuit.

  Examples of the material of the fusion layer 14b include a thermosetting resin such as a polyurethane resin, a polyester resin, and a polyesterimide resin. Of these, polyurethane resins and polyester resins are preferred. The resin composition for forming the fusion layer that forms the fusion layer 14b contains a crosslinking agent and a solvent. In addition, various additives are included as needed. The crosslinking agent, solvent and additive are not particularly limited, and various crosslinking agents, solvents and additives depending on the kind of polyurethane resin, polyester resin, polyesterimide resin and the required characteristics are used as needed. . The thickness of the fusion layer 14b is not particularly limited, either, but may be, for example, about 0.001 mm.

  Winding stress is applied when the resin tape with the fusion layer is wound horizontally, but at that time or subsequent heating, the stress is relaxed or dispersed, so that it is possible to reduce the rigidity due to the concentration of the winding stress, and from the viewpoint of flexibility. Is preferable.

  In addition, at the time of horizontal winding, by applying a temperature lower than the specific temperature for performing the cross-linking reaction, it is possible to perform horizontal winding in a temporary adhesion state. By doing so, it is possible to prevent a winding deviation from occurring in the horizontally wound resin tape 14a. The temperature at which such a temporary adhesion state is generated is preferably lower than the temperature at which the crosslinking reaction of the fusion layer 14b occurs. For example, regarding "the cross-linking reaction occurs at a specific temperature or higher and adheres", when a polyester-based thermosetting resin is used as the resin composition for forming a fusion layer, for example, the resin is cured at about 160 to 200 ° C. Can be adhered on the external conductor 13 by the above method, but as a temporary adhesion state, it can be temporarily cured at a temperature lower than the temperature, about 80 to 130 ° C., and temporarily adhered. In the case of other thermosetting resins, those having a “specific temperature” of about 90 to 150 ° C. (for example, epoxy-based thermosetting resin, manufactured by TOMOEGAWA, Elephan CS) are temporarily bonded at about 50 to 70 ° C. It can be. When the resin tape with the fusion layer is horizontally wound, it is possible to prevent the occurrence of winding deviation due to such an operation. The temporary bonding state and the bonding state can be roughly evaluated by a heating weight loss curve measured using a thermobalance. For example, the curing behavior of the resin can be analyzed by considering the weight loss on heating as hardness. By such an evaluation, the “temporary bonding state temperature” and the “specific bonding temperature” can be arbitrarily designed. You can do it.

  It is preferable that the horizontal winding pitch P3 when the resin tape with the fusion layer is horizontally wound is equal to or substantially equal to the horizontal winding pitch P2 of the second metal resin tape 13c. The overlapping of the resin tape 14a fixed by the fusion layer 14b is ensured by setting the wrap of the resin tape with the fusion layer and the horizontal pitch P3 and the horizontal pitch P2 of the second metal resin tape 13c as described above. After that, the resin tape 14a can be wound horizontally at a pitch P3 at which the displacement of the metal layer disposed thereunder is less likely to occur. Therefore, even when the metal wire 13b is bent and the metal wire 13b is slightly displaced, stable contact between the second metal resin tape 13c covering the metal wire 13b and the resin tape 14a adhered thereon can be obtained. Is held. As a result, stable shield characteristics can be maintained.

  The horizontal winding direction of the resin tape with the fusion layer may be the same as or opposite to the horizontal winding direction of the second metal resin tape 13c described above. preferable.

<Multi-core communication cable>
As shown in FIG. 1, the multi-core communication cable 10 includes a core material 3, two or more coaxial wire sets 2 arranged on the outer periphery of the core material 3, and a press-wrap that covers and bundles the two or more coaxial wire sets 2. It comprises at least a tape 5, a shield layer 6 covering the holding tape 5, and a resin extruding sheath 7 covering the shield layer 6. Note that the holding tape 5, the shield layer 6, the resin extruding sheath 7, and the like that cover two or more sets of coaxial electric wires 2 may be referred to as a sheath 4. The multi-core communication cable 10 includes two or more coaxial cable sets 2 each including two coaxial cables described above. For example, in the example of FIG. The number of the coaxial wire sets 2 may be at least two or more, and the upper limit is not particularly limited, but may be about 4 to 8.

(Core material)
The core material 3 is located at the center of the multi-core communication cable 10 and can be in various modes. For example, if a high-tension tension member that functions as a winding core is used, it acts to reinforce the axial strength and flexibility of the multi-core communication cable 10. For example, a fiber yarn composed of a plurality of fibers or a fiber bundle obtained by bundling the fiber yarns is preferably used. Examples of the fiber constituting the fiber bundle or the fiber yarn include polyester fibers such as Tetron (registered trademark), wholly aromatic polyamide fibers such as Kevlar (registered trademark), and polyarylate fibers such as Vectran (registered trademark). Glass fibers and the like can be mentioned. Further, the core material 3 may be formed by arbitrarily combining fibers of different materials or fiber yarns having different outer diameters. The core material 3 has a concentric (true circular) cross section in which these fiber bundles or fiber yarns are formed into a collective wire, a stranded wire, or a woven wire. In addition, "dtex" indicates a fiber yarn in terms of weight, and 1 dtex means that the length is 10000 m and 1 g.

  As another example of the core member 3, a power line, a signal line, or a drain line may be arbitrarily selected and bundled. These can be arbitrarily selected according to requirements such as the application of the multi-core communication cable 10.

(Core material holding tape)
The core material 3 is preferably covered with a core material holding tape 8. The core material holding tape 8 is not particularly limited as long as the core material 3 can be pressed so that the core material 3 is not loosened, and a preferable example is a polyester tape. The thickness is not particularly limited, either, and is preferably in the range of 0.003 to 0.01 mm. The outer diameter of the core material 3 after being wound by the core material holding tape 8 is arbitrarily selected according to its role and use, and is not particularly limited. The tape width is also arbitrarily selected depending on the winding pitch and the like, and is not particularly limited.

(Sheath sheath)
The outer sheath 4 is composed of a holding tape 5, a shield layer 6, a resin extruding sheath 7, and the like. The holding tape 5 is provided so as to cover and bundle two or more coaxial electric wire sets 2. The holding tape 5 is not particularly limited as long as the plurality of coaxial wire sets 2 can be held so as not to be separated, and examples thereof include a polyester tape and a paper tape, and a Washi tape is particularly preferable. it can. The thickness of the press-winding tape 5 is not particularly limited, either, 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. Note that, when signal wires and the like are provided as necessary together with the coaxial electric wire set 2, the press-winding tape 5 acts to collectively wind and hold them.

  The shield layer 6 covers the holding tape 5. The shield layer 6 may be a braided or horizontally wound thin metal wire similar to the thin metal wire constituting the second outer conductor 13b, or may be an insulating tape with a metal layer (for example, A polyethylene terephthalate film or the like, or a combination of both. In the example of FIG. 1, a thin wire braid is provided as the shield layer 6. The shield layer 6 can be provided by arbitrarily selecting a thin metal wire similar to the above-described thin metal wire of the second outer conductor 13b. The thickness of the shield layer 6 varies depending on the braid of the thin metal wire, the type of the horizontal winding, or the type of the insulating tape with the metal layer, but may be any thickness as long as the shield performance according to each can be exhibited. However, it is within a range of, for example, about 0.05 to 0.30 mm.

  The shield layer 6 may be a single shield layer or a double or more shield layer. As for the two-layer horizontally wound shield layer, each layer may be in the same direction or in the opposite direction. By making the shield layer a double conductor horizontal winding and winding them in the opposite direction, disconnection can be made less likely to occur. In particular, compared to a shield conductor formed by vertically attaching or horizontally winding a metal tape, it is less likely to be disconnected, and the bending resistance can be improved.

  The resin extrusion sheath 7 is provided so as to cover the shield layer 6. The material of the resin extruded sheath 7 is not particularly limited as long as the resin extruded sheath 7 is insulative, as in the case of the jacket 14. For example, various commonly applied materials can be used, and for example, a fluorine-based resin such as ETFE, a vinyl chloride resin, or a polyolefin resin such as polyethylene may be used. Or a polyester resin such as polyethylene terephthalate. The thickness of the resin extrusion sheath 7 can be, for example, in a range of about 0.3 to 1.5 mm. By providing such a resin extruding sheath 7, the finished outer diameter of the multi-core communication cable 10 is not particularly limited, but can be, for example, about 5.0 mm as in the embodiment described later.

  Note that a tape-wrapped sheath may be used instead of the push-out sheath 7. As the tape-wound sheath, various kinds of materials used as insulating tapes of coaxial electric wires can be arbitrarily selected and used within a range satisfying required characteristics.

  As described above, the multi-core communication cable 10 according to the present invention can suitably transmit a high-speed digital signal of 10 Gbps or more, hardly causes breakage or cracks in the outer conductor even when bent, and has a transmission characteristic. It is possible to provide a flexible multi-core communication cable which is hardly reduced.

  Hereinafter, the present invention will be described more specifically with reference to examples. Note that the present invention is not limited to the following embodiments.

[Example 1]
First, a coaxial electric wire 1 having the form shown in FIG. 2 was manufactured. For each coaxial electric wire 1, an AWG 30 (outer diameter of about 0.3 mm) in which seven tin-plated annealed copper wires having a diameter of 0.10 mm were twisted as the center conductor 11 was used. Next, a 0.24 mm-thick FEP resin (manufactured by DuPont) was extruded on the outer periphery of the center conductor 11 to have an outer diameter of 0.78 mm. Next, the external conductor 13 having a triple structure including the first external conductor 13a, the second external conductor 13b, and the third external conductor 13c was formed. As the first outer conductor 13a, a first metal resin tape having a width of 3 mm and a copper foil having a thickness of 0.008 mm provided on a PET base material having a thickness of 0.004 mm is used. (The side of the second external conductor 13b). The second outer conductor 13b was left-hand wound at a pitch P1 of 14 mm using 59 tin-plated soft copper wires (thin metal wires; abbreviated as TCW) having a diameter of 0.05 mm. Next, as the third outer conductor 13c, a second metal resin tape having a width of 3 mm and a copper foil having a thickness of 0.008 mm provided on a PET base material having a thickness of 0.004 mm was used. It was wound rightward at a pitch P2 of 4 mm so as to be on the side of the external conductor 13b. The outer diameter after the provision of the triple-layered external conductor 13 was 0.94 mm. Then, a PFE tape (resin tape 14a) with a fusion layer having a thickness of 0.004 mm and a width of 3 mm was used as the envelope 14, and the fusion layer 14b was set to the second metal resin tape side, and the second metal The left winding was opposite to the winding direction of the resin tape. The horizontal winding pitch P3 at that time was 4 mm. The outer diameter of each coaxial cable 1 was 0.95 mm. The two coaxial electric wires were colored by coloring the resin tape.

  Thereafter, 280 dtex × 3 aramid fibers were used as the core member 3 as a tension member, and the tension member was covered with a holding tape 8 and bound. Thereafter, four sets of the coaxial electric wire sets 2 each composed of the two coaxial electric wires obtained above were used, and the core material 3 was right-twisted at a pitch of 70 mm around the outer periphery of the core material 3 with the axial position being the center position. Thereafter, the four coaxial cable sets 2 were wrapped with a 15 mm width Japanese paper tape 5 so as to cover them. Thereafter, as the shield layer 6, 105 tinned annealed copper wires having a diameter of 0.10 mm were used and right-handed. The outer diameter after providing the shield layer 6 was 4.2 mm. Thereafter, a soft PVC having a thickness of 0.4 mm was extruded as a resin extruding sheath 7 to obtain a multi-core communication cable 10 having a final outer diameter of 5.0 mm. The obtained multi-core communication cable 10 was a flexible multi-core communication cable whose characteristics were hardly deteriorated even when bent.

[Example 2]
In Example 1, as the insulator 12 provided on the outer periphery of the center conductor 11, a hollow structure made of a PFA resin having a thickness of 0.20 mm was extruded to have an outer diameter of 0.71 mm. The hollow-structured insulator 12 is formed by extruding a PFA resin (manufactured by DuPont) at 350 ° C. with a hollow-structure die nipple to form an inner annular portion having a thickness of 0.05 mm and a thickness of 0.1 mm. It is a cross-sectional configuration surrounded by a 05 mm outer annular portion and a 0.05 mm thick connecting portion. The outer diameter of the entire insulator was 0.71 mm, and the porosity of the void was 29% with respect to the area of the entire insulator. Otherwise, in the same manner as in Example 1, a multicore communication cable 10 having a final outer diameter of 4.8 mm was produced. The obtained multi-core communication cable 10 was a flexible multi-core communication cable whose characteristics were hardly deteriorated even when bent.

DESCRIPTION OF SYMBOLS 1 Coaxial electric wire 2 Coaxial electric wire set 3 Core material 3a Inner-layer holding tape 4 Outer sheath 5 Outer-layer holding tape 6 Shield layer 7 Resin extruded layer 8 Core member holding tape 10 Multi-core communication cable 11 Central conductor 12 Insulator 13 External Conductor 13a First outer conductor (first metal resin tape)
13b 2nd outer conductor (thin metal wire)
13c Third outer conductor (second metal resin tape)
Reference Signs List 14 envelope 14a resin tape 14b fusion layer Y longitudinal direction P1 horizontal winding pitch of thin metal wire P2 horizontal winding pitch of second metal resin tape P3 horizontal winding pitch of resin tape 41 fixing plate 42 fixing portion

Claims (5)

A multi-core communication cable including two or more coaxial cable sets each including two coaxial cables, and covering the two or more coaxial cable groups with a sheath sheath, wherein the coaxial cable includes a central conductor and an insulator. And an outer conductor and a jacket in that order,
The outer conductor includes a first outer conductor formed by vertically attaching a first metal resin tape having a metal layer surface outside on the insulator, and a thin metal wire wound horizontally on the first outer conductor. A multi-core communication cable comprising: a second outer conductor; and a third outer conductor formed by horizontally winding a second metal resin tape having a metal layer surface inside on the second outer conductor.   The multi-core communication cable according to claim 1, wherein the diameter of the thin metal wire as the second outer conductor is 1/10 to 1/20 of the outer diameter of the insulator.   The thickness of the metal layer forming the first outer conductor and the third outer conductor is in the range of 2 to 8 μm, and the thickness of the resin base forming the first outer conductor and the third outer conductor is 2 to 8 μm. The multi-core communication cable according to claim 1, wherein the length is within a range of 20 μm.   The outer cover is formed by winding the resin layer with a fusion layer horizontally with the fusion layer facing the outer conductor, and the third outer conductor and the resin tape are bonded to each other via the fusion layer. The multi-core communication cable according to any one of claims 1 to 3, wherein The said sheath sheath has one or two or more press-winding tapes, a shield layer, and a resin extrusion layer in this order from the inner side to the outer side, The said sheath is any one of Claims 1-4. Multi-core communication cable.