JP6774462B2 - Multi-core communication cable - Google Patents

Description

The present invention relates to a multi-core high-speed signal transmission cable having a plurality of coaxial electric wires. More specifically, the present invention can suitably transmit a high-speed digital signal of 10 Gbps or more, and its characteristics are unlikely to deteriorate even when bent. Regarding flexible multi-core communication cables.

In recent years, communication cables typified by USB3.1 and the like tend to be required to have a smaller diameter and flexibility because they are frequently used for handling such as insertion and removal as the frequency of use increases. As an improvement in the diameter reduction and flexibility required for a communication cable, for example, in Patent Document 1, a high-speed digital signal of 10 Gbps or more can be suitably transmitted, and multi-core twisted or bent. Even in this case, we are proposing a high-speed signal transmission cable in which the signal transmission speed is constant, the characteristics are unlikely to deteriorate, and the variation in the electrical length of each cable is small. This technology is a high-speed signal transmission cable including 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, and the coaxial line is an internal conductor. It has a hollow core body and an outer 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.

Further, Patent Document 2 proposes a technique for providing a multi-core cable capable of suppressing crosstalk between coaxial electric wire pairs. In this technique, two or more pairs of coaxial wires are included in which two coaxial wires are in contact with each other and arranged in parallel, and each coaxial wire is composed of a central conductor, an insulator, an outer conductor, and a jacket, respectively. There is. 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, and the thin metal wire of the inner layer portion. The winding direction of the metal resin tape is opposite to the winding direction of the metal resin tape in the outer layer, and the angle of the winding direction of the metal resin tape with respect to the winding direction of the thin metal wire is 30 degrees or more and 90 degrees or less, and a plurality of coaxial cables are used. By including two or more pairs of coaxial wires in which two coaxial wires are in contact with each other and arranged in parallel, the crosstalk between the pairs of coaxial wires is set to -40 dB or less.

WO2013 / 069755 Japanese Unexamined Patent Publication No. 2016-207658

Regarding the above-mentioned prior art, the cable of Patent Document 1 has poor flexibility and insufficient bending resistance. For example, if bending stress is repeatedly applied to the same portion, a small break may occur in the metal tape of the coaxial cable, and the bending stress tends to concentrate starting from the broken portion. As a result, the outer conductor may be destroyed. Such a coaxial cable having insufficient bending resistance is not suitable for a high-frequency communication cable that requires high flexibility by assembling a plurality of coaxial cables and integrating them.

Further, in the coaxial cable of Patent Document 2, since the metal resin tape is wound around the outer circumference around which the thin metal wire is wound horizontally, the outer diameter becomes thick and the flexibility becomes poor, and the assembled multi-core cable also becomes thick and flexible. There is a problem that it becomes scarce. In addition, the thin metal wire is likely to come apart during the terminal strip, the workability is poor, and there is a risk of a short circuit.

The present invention has been made to solve the above 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 have flexibility in which the characteristics are not easily deteriorated even when bent. It is to provide a multi-core communication cable with a certain.

The multi-core communication cable according to the present invention is a multi-core communication cable including two or more sets of coaxial electric wires composed of two coaxial electric wires, and the two or more sets of coaxial electric wires are covered with a sheath. The coaxial electric wire includes a central conductor, an insulator, an outer conductor wound horizontally with a thin metal wire, and an outer body wound horizontally with the fused layer of a resin tape having a fusion layer on the outer conductor side. It is characterized in that the thin metal wire and the resin tape are adhered to each other via the fusion layer.

According to the present invention, since the thin metal wire and the resin tape are wound horizontally, the flexibility is 1.5 to 2 times or more as compared with the outer conductor of the conventional vertical attachment structure or horizontal winding structure of the metal tape. As well as improving, stress concentration is less likely to occur, so disconnection is less likely to occur. Further, since the fine metal wire and the resin tape are adhered to each other via the fusion layer, it is possible to prevent the fine metal wire from being scattered during the terminal strip, and the workability is good and there is no risk of short circuit. Further, since the fused layer is fused only to the surface layer of the thin metal wire, flexibility based on the displacement movement of the thin metal wire in the bulk can be generated.

In the multi-core communication cable according to the present invention, it is preferable that the horizontal winding pitch of the resin tape is within the range of 1/5 to 1/2 of the horizontal winding pitch of the thin metal wire.

According to the present invention, the thin metal wire can be pressed without a gap. Adhesion can be maintained by setting the value to 1/2 or less, but if it exceeds 1/2, the adhesion may not be maintained, and when the cable is bent, there is a gap in the outer conductor in which the thin metal wire is wound horizontally. This may occur and the high frequency transmission characteristics may deteriorate. Further, if it is less than 1/5, the productivity deteriorates.

In the multi-core communication cable according to the present invention, it is preferable that the resin tape is a polyethylene terephthalate film with a cohesive layer.

According to the present invention, the PET tape with a fusion layer is optimal in terms of hardness and elongation, and the thickness is not particularly limited, but is preferably in the range of 2 to 6 μm.

In the multi-core communication cable according to the present invention, it is preferable that the diameter of the thin metal wire is within the range of 1/10 to 1/20 of the outer diameter of the insulator.

According to the present invention, by setting the diameter of the thin metal wire within the above range, it is possible to suppress the occurrence of disconnection while maintaining the horizontal winding density of the thin metal wire and maintaining good high-frequency transmission characteristics.

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

According to the present invention, it is possible to provide a flexible multi-core communication cable capable of suitably transmitting a high-speed digital signal of 10 Gbps or more and having characteristics that are not easily deteriorated even when bent.

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 explanatory drawing which shows the measuring method of the softness of a multi-core communication cable. It is a graph which shows the result of measurement by the method of FIG. It is explanatory drawing which shows the other measuring method of the softness of a multi-core communication cable. It is a graph which shows the result of measurement by the method of FIG.

An embodiment of the multi-core communication cable according to the present invention will be described with reference to the drawings. It should be noted that the present invention includes the invention of 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 to the description of the embodiments and the drawings. Not a thing.

[Multi-core communication cable]
As shown in FIGS. 1 and 2, the multi-core communication cable 10 according to the present invention is a multi-core communication cable 10 including two or more coaxial wire sets 2 composed of two coaxial wires 1 and 1. Then, the coaxial electric wire 1 is laterally arranged with the central conductor 11, the insulator 12, the outer conductor 13 in which the thin metal wire 13a is wound horizontally, and the fusion layer 14b of the resin tape 14a with the fusion layer 14b on the outer conductor side. The wound outer body 14 is provided in that order, and the thin metal wire 13a and the resin tape 14a are configured to be fused via the fusion layer 14b.

Since the thin metal wire 13a and the resin tape 14a are horizontally wound in this multi-core communication cable 10, it is 1.5 to 2 times as much as the outer conductor of the conventional vertical attachment structure or horizontal winding structure of the metal tape. As described above, the flexibility is improved, and stress concentration is less likely to occur, so that disconnection is less likely to occur. Further, since the thin metal wire 13a and the resin tape 14a are adhered to each other via the fusion layer 14b, it is possible to suppress the thin metal wire 13a from coming apart during the terminal strip, which is good in workability and may cause a short circuit. Absent. Further, since the fused layer 14b is fused only to the surface layer of the thin metal wire 13a, flexibility based on the displacement movement of the thin metal wire in the bulk can be generated.

Hereinafter, each component will be described in detail.

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

(Center conductor)
The central conductor 11 is composed of one strand extending in the longitudinal direction Y of the coaxial electric wire 1, 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 aluminum. 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 central conductor 11 is also not particularly limited, but may be circular (including an elliptical shape), rectangular, or the like. The outer diameter of the central conductor 11 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 11 if necessary. The type and thickness of the insulating film are not particularly limited, but for example, those that decompose well during soldering are preferable, and thermosetting polyurethane films and the like can be preferably mentioned.

(Insulator)
The insulator 12 is a low dielectric constant insulating layer provided continuously on the outer periphery of the central conductor 11 in the longitudinal direction Y. The material of the insulator 12 is not particularly limited, but for example, a fluororesin having a low dielectric constant such as PFA, ETFE, or FEP is preferable, and good high-frequency transmission characteristics can be exhibited. The material of the insulator 12 may contain a colorant. The method for forming the insulator 12 is not particularly limited, and examples thereof include extrusion and coating. The structural form 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.

(Outer conductor)
The outer conductor 13 is provided on the outer periphery of the insulator 12. The outer conductor 13 is provided separately from the shield layer 6 that covers the entire surface, which will be described later. The outer conductor 13 is formed by horizontally winding a thin metal wire 13a. The thickness of the outer conductor 13 varies depending on the wire diameter and the number of twists of the thin metal wire 13a used, and is not particularly limited.

The thin metal wire 13a is not particularly limited as long as it is a well-conductive metal thin wire provided on the outer periphery of the dielectric layer (insulator 12) 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 13a is also not particularly limited, and examples thereof include those in the range of about 0.04 to 0.1 mm. The number of thin metal wires 13a is arbitrarily selected depending on the outer diameter of the insulator 12 and the planned outer diameter of the coaxial electric wire 1, but 48 on the insulator 12 having a diameter of 0.05 mm as in the embodiment described later. The thin metal wire 13a of the book can be horizontally wound to form the outer conductor 13.

The winding pitch P1 when the thin metal wire 13a is wound horizontally differs depending on the outer diameter of the insulator 12. For example, when the outer diameter of the insulator 12 is 0.78 m as in the embodiment described later, the pitch P1 is set. It is preferably about 14 mm.

(Outer 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 with the insulating fusion layer with the fusion layer 14b side as the outer conductor side. Examples of the material of the resin tape 14a constituting the outer body 14 include polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyamide (PA), polyimide (PI), polyphenylene sulfide (PPS), and ethylene-4 foot. Ethylene chemical copolymer (ETFE), ethylene tetrafluoride-propylene hexafluoride copolymer (FEP), fluorinated resin copolymer (perfluoroalkoxy alkane resin: 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 are usually single-layered, but may have two or more layers depending on the purpose. The thickness of the resin tape 14a is not particularly limited as long as it is thick enough to secure the required dielectric strength, but as an example, it can be about 0.004 mm as in the examples described later. The resin tape 14a may be colored. Coloring can be provided by incorporating a colorant in the resin tape 14a or by 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 electric wire 1, and the coaxial electric wires 1 having individual roles can be identified by the colors.

The fusion layer 14b is provided on one side of the resin tape 14a. The material of the fused layer 14b 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 fusion layer 14b 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 and cause an outer conductor. Adhere to 13. By doing so, for example, it is possible to prevent the thin metal wire from coming apart during the terminal strip, the workability is good, and there is no risk of a short circuit. Further, since the fused layer 14b is fused only to the surface layer of the thin metal wire 13a, flexibility based on the displacement movement of the thin metal wire in the bulk can be generated.

Examples of the material of the fused layer 14b 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 forming the fusion layer 14b 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 necessary. .. The thickness of the fused layer 14b is also not particularly limited, but can be, for example, about 0.001 mm as in the examples described later.

Winding stress is applied when the resin tape with a fusion layer is wound horizontally, but the stress is relaxed or dispersed by heating at that time or afterwards, so that rigidity due to concentration of winding stress can be relaxed, and from the viewpoint of flexibility. Therefore, it becomes preferable.

It should be noted that, at the time of horizontal winding, by applying a temperature lower than the specific temperature at which the cross-linking reaction is carried out, it is possible to make a temporary adhesive state and perform horizontal winding. By doing so, it is possible to prevent the horizontally wound resin tape 14a from being unwound. The temperature at which such a temporary bonding state occurs is preferably a temperature lower than the temperature at which the crosslinking reaction of the fused layer 14b occurs. For example, regarding "a cross-linking reaction occurs at a specific temperature or higher and adhesion", when a polyester-based thermosetting resin is used as the resin composition for forming a fusion layer, it is cured at, for example, about 160 to 200 ° C. It can be temporarily bonded on the outer conductor 13, but as a temporary bonding state, it can be temporarily cured at about 80 to 130 ° C., which is lower than the temperature, and temporarily bonded. Further, among other thermosetting resins, those having a "specific temperature" of about 90 to 150 ° C. (for example, epoxy-based thermosetting resin, manufactured by TOMOEGAWA, Elephant CS) are temporarily adhered at about 50 to 70 ° C. Can be. When the resin tape with a fusion layer is wound horizontally, it is possible to prevent winding misalignment due to such an operation. The temporary bonding state and the bonding state can be roughly evaluated by the heating weight loss curve measured using a hot balance. For example, the curing behavior of a resin can be analyzed by considering the heating weight lapse rate as hardness. By such evaluation, the "temporary bonding state temperature" and the "specific bonding temperature" can be arbitrarily designed, and the temperature difference is set to be large, for example, 80 ° C to 120 ° C, or small, such as 0 ° C to 50 ° C. It can be a thing.

The horizontal winding pitch P2 when the resin tape with a fusion layer is wound horizontally is preferably in the range of 1/5 to 1/2 of the horizontal winding pitch P1 of the thin metal wire 13a. By doing so, the resin tape 14a can be wound without a gap, and the thin metal wire 13a can be pressed. By setting the horizontal winding pitch P1 to 1/2 or less, the adhesion between the resin tapes 14a can be maintained, but if it exceeds 1/2, the adhesion may not be maintained, and when the cable is bent, the adhesion may not be maintained. A gap may occur in the outer conductor in which the thin metal wire is wound horizontally, and the high frequency transmission characteristics may deteriorate. If it is less than 1/5, the pitch P2 is too small and the productivity deteriorates. The horizontal winding direction of the resin tape with the fusion layer may be the same as the horizontal winding direction of the above-mentioned thin metal wire 13a or the opposite 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 can be in the range of 3 to 10 mm, for example, as in the examples described later.

<Multi-core communication cable>
As shown in FIG. 1, the multi-core communication cable 10 is a press winding that covers and bundles the core material 3, two or more sets of coaxial electric wire sets 2 arranged on the outer periphery of the core material 3, and two or more sets of coaxial electric wire sets 2. It is composed of at least a tape 5, a shield layer 6 that covers the presser foot tape 5, and a resin extrusion sheath 7 that covers the shield layer 6. The presser winding tape 5, the shield layer 6, the resin extruded sheath 7, and the like that cover two or more sets of coaxial electric wire sets 2 may be referred to as a jacket sheath 4. The multi-core communication cable 10 includes two or more sets of coaxial electric wires 2 composed of the above-mentioned two coaxial electric wires. For example, in the example of FIG. 1, four coaxial electric wire sets 2 are included. The number of the coaxial electric 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 forms. For example, a high-tensile tension member that functions as a winding core acts to reinforce the axial strength and flexibility of the multi-core communication cable 10. As an example, a fiber thread composed of a plurality of fibers or a fiber bundle obtained by bundling the fiber threads is preferably used. Examples of the fibers constituting the fiber bundle or fiber yarn include polyester fibers such as Tetron (registered trademark), all-aromatic polyamide fibers such as Kebra (registered trademark), and polyarylate fibers such as Vectran (registered trademark). Glass fiber and the like can be mentioned. Further, the core material 3 may be an arbitrary composite of fibers made of different materials or fiber threads having different outer diameters. The core material 3 has a concentric (perfect circular) cross section in which these fiber bundles or fiber threads are made into a collecting wire, a stranded wire, or a braided wire. In addition, "dtex" indicates a fiber yarn in terms of weight, and 1 dtex means that the length is 10000 m and the weight is 1 g.

As another example of the core material 3, the power line, the signal line, and the drain line may be arbitrarily selected and bundled. These can be arbitrarily selected according to the 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 presser winding tape 8 is not particularly limited as long as it can hold the core material 3 so as not to come apart, but polyester tape or the like can be preferably mentioned, for example. The thickness is not particularly limited, and is preferably in the range of 0.003 to 0.01 mm. The outer diameter of the core material 3 after being wound with the core material presser winding tape 8 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.

(Outer sheath)
The outer sheath 4 is composed of a presser foot tape 5, a shield layer 6, a resin extruded sheath 7, and the like. The presser foot tape 5 is provided so as to cover and bundle two or more coaxial electric wire sets 2. The presser foot tape 5 is not particularly limited as long as it can hold the plurality of coaxial electric wire sets 2 so as not to come apart, but polyester tape, paper tape and the like can be mentioned, and Japanese paper tape is particularly preferable. it can. The thickness is 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. In addition, when the signal line or the like is provided together with the coaxial electric wire set 2 as needed, the presser winding tape 5 acts to wind and hold them together.

The shield layer 6 covers the presser foot tape 5. The shield layer 6 may be a braided or horizontally wound material similar to the fine metal wire constituting the outer conductor 13, or an insulating tape with a metal layer (for example, a polyethylene terephthalate film with a copper layer). Etc.), or a combination of both of them. In the example of FIG. 1, the thin wire braid is provided as the shield layer 6. As the shield layer 6, the same material as the fine metal wire of the outer conductor 13 described above can be arbitrarily selected and provided. The thickness of the shield layer 6 varies depending on the type of braided metal wire, horizontal winding, or insulating tape with a metal layer, but it is only limited as long as it is thick enough to exhibit the shielding performance according to each. However, it is in the 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 horizontal winding shield layer, each layer may be in the same direction or in the opposite direction. By winding the shield layer horizontally with double conductors and winding them horizontally in the opposite direction, it is possible to prevent disconnection from occurring. In particular, as compared with a shield conductor formed by vertically attaching or horizontally winding a metal tape, it is less likely to break and the bending resistance can be improved.

The resin extrusion sheath 7 is provided so as to cover the shield layer 6. As with the outer body 14, the material of the resin extruded sheath 7 is not particularly limited as long as it has an insulating property. 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 resin extruded sheath 7 can be, for example, in the range of about 0.3 to 1.5 mm. By providing such a resin extruded sheath 7, the finished outer diameter of the multi-core communication cable 10 is not particularly limited.

A tape-wrapped sheath may be used instead of the extruded sheath 7. As the tape-wrapped sheath, various types used as insulating tapes for coaxial electric wires can be arbitrarily selected and used within a range satisfying necessary 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, and has a flexible multi-core communication whose characteristics are not easily deteriorated even when bent. Cables can be provided.

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]
First, the coaxial electric wire 1 having the form shown in FIG. 2 was produced. For each coaxial electric wire 1, as the central conductor 11, 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. Next, a 0.24 mm thick FEP resin (manufactured by DuPont) layer was extruded and formed on the outer periphery of the central conductor 11 to have an outer diameter of 0.78 mm. Next, the outer conductor 13 was formed. The outer conductor 13 was wound with 48 tin-plated annealed copper wires (thin metal wires 13a, abbreviated as TCW) having a diameter of 0.05 mm in a left-horizontal winding at a pitch P1 of 14 mm. The outer diameter after providing the outer conductor 13 was 0.88 mm. Then, as the outer cover 14, a PFE tape (resin tape 14a) with a fusion layer having a thickness of 0.004 mm and a width of 4.5 mm is used, and the side of the fusion layer 14b is set to the outer conductor side, and the outer conductor 13 It was wound in the right direction opposite to the winding direction. The winding pitch P2 at that time was set to 4 mm. The outer diameter of each coaxial electric wire 1 was 0.89 mm. The resin tape 14a was colored and the two coaxial wires were color-coded.

Then, as the core material 3, 280 dtex × 3 aramid fibers were used as tension members, and the tension members were covered and bundled with the presser winding tape 8. Then, four sets of coaxial electric wire sets 2 composed of the two coaxial electric wires obtained above were used, and the core material 3 was right-twisted around the outer periphery of the core material 3 at a pitch of 70 mm with the core material 3 as the axial center position. Then, it was pressed and wound with Japanese paper tape 5 having a width of 15 mm so as to cover the four sets of coaxial electric wire sets 2. Then, as the shield layer 6, 105 tin-plated annealed copper wires having a diameter of 0.10 mm were used and wound right-handed. The outer diameter after the shield layer 6 was provided was 4.2 mm. Then, as the resin extrusion sheath 7, soft PVC having a thickness of 0.4 mm was extruded to obtain a multi-core communication cable 10 having a final outer diameter of 5.0 mm. At this time, the winding pitch P2 of the outer body / the winding pitch P1 of the outer conductor = 4/14.

[Example 2]
In Example 1, a PFE tape with a fusion layer having a width of 3.5 mm was wound right-handed as an outer cover at a pitch P2 of 3 mm. The multi-core communication cable 10 of Example 2 was produced in the same manner as in Example 1 except for the above. At this time, the winding pitch P2 of the outer body / the winding pitch P1 of the outer conductor = 3/14.

[Example 3]
In Example 1, a PFE tape with a fusion layer having a width of 7.5 mm was wound right as an outer cover at a pitch P2 of 7 mm. The multi-core communication cable 10 of Example 3 was produced in the same manner as in Example 1 except for the above. At this time, the winding pitch P2 of the outer body / the winding pitch P1 of the outer conductor = 7/14.

[Comparative Example 1]
In Example 1, a PFE tape with a fusion layer having a width of 9.5 mm was wound right-handed as an outer cover at a pitch P2 of 9 mm. The multi-core communication cable 10 of Comparative Example 1 was produced in the same manner as in Example 1 except for the above. At this time, the winding pitch P2 of the outer body / the winding pitch P1 of the outer conductor = 9/14.

[Bending resistance test]
FIG. 3 is an explanatory diagram showing a method of measuring the softness of the multi-core communication cable 10, and FIG. 4 is a graph showing the result. Further, FIG. 5 is an explanatory diagram showing another measuring method of the softness of the multi-core communication cable 10, and FIG. 6 is a graph showing the result.

(Measurement conditions in FIG. 3)
Both ends of a multi-core communication cable with a length of 500 mm are fixed with fixing portions 41, and the highest point (almost the central portion) of the multi-core communication cable 10 that is bent upward is set to a height of 1/2 the loop height. It was pushed in, and the pushing load at that time was measured. The indentation length before and after the indentation was measured. The measurement position was the center of the fixed portions 41 on both sides. The result is shown in FIG. In FIG. 4, the "coaxial type" is the multi-core communication cable of the first embodiment, and the "STP type" is the coaxial electric wire set consisting of two coaxial electric wires in the first embodiment. A 0.24 mm thick FEP resin (manufactured by DuPont) layer is extruded and formed on the outer circumference of a central conductor 11 using AWG30 (outer diameter of about 0.3 mm) obtained by twisting seven tin-plated annealed copper wires having a diameter of 0.10 mm. This is a shielded twisted pair type multi-core communication cable using two insulated wires having an outer diameter of 0.78 mm twisted together and an outer conductor and an outer cover formed on the outer circumference thereof.

(Measurement conditions in FIG. 5)
Both ends of a multi-core communication cable with a length of 500 mm are fixed by fixing portions 41, and the lowest point (almost the central portion) of the multi-core communication cable 10 having a shape in which a weight 42 having a weight of 0 g, 200 g, or 400 g is curved and bulged. The maximum width before and after hanging was measured. The result is shown in FIG. In FIG. 6, since it is referred to as "coaxial type", it is the multi-core communication cable of the first embodiment, and "STP type" is a shield twisted pair type multi-core communication cable using a pair of twisted wire sets.

[result]
From the measurement results, it was found that the multi-core communication cable of Example 1 was flexible. Further, the multi-core communication cables of Examples 1 to 3 had better adhesion than the multi-core communication cables of Comparative Example 1.

1 Coaxial wire 2 Coaxial wire assembly 3 Core material 3a Inner layer presser winding tape 4 Outer sheath 5 Outer layer presser winding tape 6 Shield layer 7 Resin extrusion layer 8 Core material presser winding tape 10 Multi-core communication cable 11 Center conductor 12 Insulator 13 External Conductor 13a Fine metal wire 14 Outer body 14a Resin tape 14b Fused layer Y Longitudinal direction P1 Horizontal winding pitch of thin metal wire P2 Horizontal winding pitch of resin tape 41 Fixed part 42 Weight

Claims (4)

It is a multi-core communication cable including two or more sets of coaxial electric wires composed of two coaxial electric wires, and the two or more sets of coaxial electric wires are covered with a sheath, and the coaxial electric wires are insulated from the central conductor. and body, has a thin metal wire and a transverse winding the outer conductor, the said fusing layer of the resin tape having a bonding layer on one side by the outer conductor side and a transverse winding the envelope body in this order, the resin tape The horizontal winding pitch of the above is within the range of 1/5 to 1/2 of the horizontal winding pitch of the thin metal wire, and the thin metal wire and the resin tape are adhered to each other via the fusion layer. A featured multi-core communication cable. The resin tape is polyethylene terephthalate film, a multi-core communication cable according to claim 1. The multi-core communication cable according to claim 1 or 2 , wherein the diameter of the thin metal wire is within the range of 1/10 to 1/20 of the outer diameter of the insulator. The invention according to any one of claims 1 to 3 , wherein the outer sheath has one or more presser-wrapping tapes, a shield layer, and a resin extruded layer in that order from the inside to the outside. Multi-core communication cable.