Shielded twisted-pair electric wire

Abstract

To provide a shielded twisted pair electric wire excellent in noise shieling.SOLUTION: A shielded twisted pair electric wire 10 includes a twisted pair electric wire 100 in which two insulated electric wires 11 are twisted together, and a shield 13 that covers the twisted pair electric wire, and an insulated electric wire 11 includes a conductor 111 and an insulated wire 112 that covers the conductor. The shield includes a first shield 131, a second shield 132, and a third shield 133 in order from the position closest to the twisted pair electric wire. The first shield includes a first metal foil-covered resin tape that is spirally wound outside of the twisted pair electric wire. The second shield has a braided conductor. The third shield has a resin tape with a second metal foil. The metal foil of the first metal foil-covered resin tape is in contact with the braided conductor, and the braided conductor is in contact with the metal foil of the second metal foil-covered resin tape.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a shielded twisted pair wire.

Background Art

[0002] Patent Document 1 discloses a twisted pair wire formed by twisting a pair of insulated wires each including a conductor and an insulating coating covering the outer periphery of the conductor, a braided shield, and a film-shaped shield having a metal film, wherein the braided shield and the film-shaped shield are laminated with each other to directly cover the outer periphery of the twisted pair wire.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In recent years, there has been a demand for a twisted pair wire that can perform high-speed communication, that is, can transmit signals in a high-frequency range, for use in cables for automobiles and the like. In order to be used for transmitting signals in a high-frequency range, a twisted pair wire having high noise shielding performance has been required.

[0005] Therefore, an object of the present disclosure is to provide a shielded twisted pair wire having excellent noise shielding performance.

Means for Solving the Problems

[0006] The shielded twisted pair wire of the present disclosure includes a twisted pair wire formed by twisting two insulated wires, and a shield covering the twisted pair wire. The insulated wire has a conductor and an insulator covering the conductor. The shield has a first shield, a second shield, and a third shield in order from the position closest to the twisted wire pair. The first shielding has a first metal foil-attached resin tape that is spirally wrapped around the outside of the twisted-pair electric wires. The second shield has a braided conductor, The third shielding has a resin tape with a second metal foil, The metal foil of the first metal foil-attached resin tape is in contact with the braided conductor, and the braided conductor is in contact with the metal foil of the second metal foil-attached resin tape. [Effects of the Invention]

[0007] According to this disclosure, it is possible to provide a shielded twisted-pair electric wire with excellent noise shielding properties. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a cross-sectional view of a shielded twisted-pair electric wire in a plane perpendicular to the longitudinal direction according to one aspect of the present disclosure. [Figure 2] Figure 2 is a cross-sectional view of a resin tape with metal foil, taken along the lamination direction between the resin layer and the metal foil. [Figure 3] Figure 3 is an explanatory diagram of the first metal foil-covered resin tape that is spirally wrapped around the outside of the twisted-pair electric wire. [Figure 4] Figure 4 is an explanatory diagram of a braided conductor. [Figure 5] Figure 5 is an explanatory diagram of the second metal foil-attached resin tape that is vertically wrapped around the outside of the second shielding. [Figure 6A] Figure 6A shows the evaluation results of the shielded twisted-pair wire Ssd12 in Experimental Example 1. [Figure 6B] Figure 6B shows the evaluation results for Ssc12 of the shielded twisted-pair electric wire related to Experimental Example 1. [Figure 7A] Figure 7A shows the evaluation results of the shielded twisted-pair wire Ssd12 in Experimental Example 2. [Figure 7B]FIG. 7B shows the evaluation results of Ssc12 of the shielded twisted pair wire according to Experimental Example 2. [Figure 8A] FIG. 8A shows the evaluation results of Ssd12 of the shielded twisted pair wire according to Experimental Example 3. [Figure 8B] FIG. 8B shows the evaluation results of Ssc12 of the shielded twisted pair wire according to Experimental Example 3. [Figure 9A] FIG. 9A shows the evaluation results of Ssd12 of the shielded twisted pair wire according to Experimental Example 4. [Figure 9B] FIG. 9B shows the evaluation results of Ssc12 of the shielded twisted pair wire according to Experimental Example 4. [Figure 10A] FIG. 10A shows the evaluation results of Ssd12 of the shielded twisted pair wire according to Experimental Example 5. [Figure 10B] FIG. 10B shows the evaluation results of Ssc12 of the shielded twisted pair wire according to Experimental Example 5. [Figure 11A] FIG. 11A shows the evaluation results of Ssd12 of the shielded twisted pair wire according to Experimental Example 6. [Figure 11B] FIG. 11B shows the evaluation results of Ssc12 of the shielded twisted pair wire according to Experimental Example 6.

MODE FOR CARRYING OUT THE INVENTION

[0009] The mode for carrying out the invention will be described below.

[0010] [Description of Embodiments of the Present Disclosure] First, the embodiments of the present disclosure will be listed and described. In the following description, the same or corresponding elements are denoted by the same reference numerals, and the same description thereof will not be repeated.

[0011] (1) The shielded twisted pair wire according to one aspect of the present disclosure includes a twisted pair wire formed by twisting two insulated wires, and a shield covering the twisted pair wire, where the insulated wire has a conductor and an insulator covering the conductor. The shield has a first shield, a second shield, and a third shield in order from the position closest to the twisted wire pair. The first shielding has a first metal foil-attached resin tape that is spirally wrapped around the outside of the twisted-pair electric wires. The second shield has a braided conductor, The third shielding has a resin tape with a second metal foil, The metal foil of the first metal foil-attached resin tape is in contact with the braided conductor, and the braided conductor is in contact with the metal foil of the second metal foil-attached resin tape.

[0012] By spirally wrapping a first metal foil-attached resin tape around the outside of the twisted-pair wire to form a first shield, the shielded twisted-pair wire can be made to suppress insertion loss and ensure the basic characteristics required of wires that transmit signals in the high-frequency range.

[0013] Furthermore, because the braided structure has excellent mechanical strength, having a braided conductor as the second shield enhances the noise shielding performance of the shielded twisted-pair wire while also increasing its durability.

[0014] By combining the first and second shielding layers with the third shielding layer, the electrical characteristics of the shielded twisted-pair wire can be improved, enhancing noise shielding. Therefore, a shielded twisted-pair wire suitable for use in high-frequency communications can be created.

[0015] Furthermore, the presence of a third shield in the shielded twisted-pair wire enhances its noise shielding capabilities even when the braiding density of the second shield is low. In this case, the low braiding density of the second shield makes the wire lightweight, flexible, and easy to handle.

[0016] (2) The second metal foil-attached resin tape may be attached vertically.

[0017] By attaching the second metal foil-coated resin tape vertically, the current flowing through the third shield can be directed along the longitudinal direction of the shielded twisted-pair wire, thereby particularly enhancing the noise shielding performance of the shielded twisted-pair wire. Therefore, even with a low braiding density for the second shield, the noise shielding performance can be sufficiently improved. In this case, because the braiding density of the second shield is low, it can be made lightweight and easy to handle.

[0018] (3) The braiding density of the braided conductor may be 40% or more.

[0019] By increasing the braiding density to 40% or more, the noise shielding performance of shielded twisted-pair wires can be particularly enhanced.

[0020] [Details of the embodiments of this disclosure] A specific example of a shielded twisted-pair electric wire according to one embodiment of this disclosure (hereinafter referred to as "this embodiment") will be described below with reference to the drawings. However, the present invention is not limited to these examples and is intended to be shown in the claims, with all modifications in the sense and scope equivalent to the claims being included. [Shielded twisted-pair electric wire] Figure 1 shows a cross-sectional view of the shielded twisted wire 10 according to this embodiment, in a plane perpendicular to the longitudinal direction. In Figure 1, the Z-axis, which is perpendicular to the plane of the paper, is the axis parallel to the longitudinal direction of the shielded twisted wire 10 or the twisted wire 100, and the XY plane formed by the X-axis and Y-axis is the cross-section perpendicular to the longitudinal direction of the shielded twisted wire 10 or the twisted wire 100. The same applies to Figures 3 and 5, which will be described later.

[0021] As shown in Figure 1, the shielded twisted-pair wire 10 of this embodiment has a twisted-pair wire 100 formed by twisting together two insulated wires 11, and a shield 13 covering the twisted-pair wire 100. Each component of the shielded twisted-pair wire 10 of this embodiment will be described below. (1) Stranded wire 100 Two insulated wires 11 can be twisted together to form a twisted-pair wire 100. As shown in Figure 1, each of the two insulated wires 11 has a conductor 111 and an insulator 112 that covers the outside of the conductor 111. (1-1) Insulated wire (1-1-1) Conductor The material of the conductor 111 is not particularly limited, but one or more conductive materials selected from, for example, copper alloys, copper, tin-plated soft copper, etc., can be used. Soft copper can be preferably used as the copper. For example, the conductor 111 may be subjected to annealing treatment to adjust its elongation, etc.

[0022] The conductor 111 may be a single wire or a stranded wire. From the viewpoint of improving the flexibility of the insulated wire 11 and the shielded stranded wire 10 including the insulated wire 11, it is preferable that the conductor 111 be a stranded wire made by twisting together multiple conductor strands 111A. (1-1-2) Insulator The material of the insulator 112 is not particularly limited and can be selected according to the characteristics required of the shielded twisted-pair wire 10.

[0023] The insulator 112 may contain, for example, a resin, and is not particularly limited to that resin. For example, one or more resins selected from fluororesins such as polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), and ethylene-tetrafluoroethylene copolymer (ETFE), or polyester resins such as polyethylene terephthalate (PET), or polyolefin resins such as polyethylene and polypropylene can be used. Polypropylene is particularly preferred among the above resins. The resin of the insulator 112 may or may not be crosslinked.

[0024] The insulator 112 may also contain additives other than the resin mentioned above, such as flame retardants, flame retardant enhancers, antioxidants, lubricants, colorants, reflective agents, opacifiers, processing stabilizers, and plasticizers. (1-2) Stranding structure of twisted wires A twisted wire pair 100 can be formed by twisting together two insulated wires 11. The twisting pitch in the twisting is not particularly limited and can be set according to the outer diameter of the insulated wires 11, etc.

[0025] For example, the twist pitch is preferably 30 mm or less, and more preferably 20 mm or less. By setting the twist pitch of the twisted wire pair 100 to 30 mm or less, loosening of the twist structure of the twisted wire pair 100 can be suppressed, making it possible to obtain stable transmission characteristics.

[0026] The lower limit of the twist pitch is not particularly limited, but it can be, for example, 5 mm or more.

[0027] The twisting pitch of the twisted wires 100 is preferably 24 times or less the outer diameter of the insulated wire 11, and more preferably 16 times or less.

[0028] By setting the twisting pitch of the twisted wire 100 to 24 times or less the outer diameter of the insulated wire 11, loosening of the twisted structure is suppressed, which in turn suppresses the increase in characteristic impedance caused by loosening of the twisted structure, thereby obtaining stable transmission characteristics. (2) Shield

[0029] The shielded twisted wire 10 according to this embodiment may have a shield 13 that covers the twisted wire 100.

[0030] The shield 13 may have a first shield 131, a second shield 132, and a third shield 133 in order from the position closest to the twisted wire pair 100.

[0031] The following describes the first shielding 131, the second shielding 132, and the third shielding 133 provided by Shield 13. (2-1) 1st shielding The first shielding 131 may have a first metal foil-covered resin tape that is spirally wrapped around the outside of the twisted wire pair 100.

[0032] A metal foil-coated resin tape that can be used in the first metal foil-coated resin tape will be described with reference to Figure 2. Figure 2 schematically shows a cross-sectional view of the metal foil-coated resin tape 20 in a plane along the lamination direction of the resin layer 21 and the metal foil 22. As shown in Figure 2, the metal foil-coated resin tape 20 has a structure in which a resin layer 21 and a metal foil 22 are laminated. That is, the metal foil-coated resin tape 20 has a structure in which a resin layer 21 and a metal foil 22 are arranged on at least the upper surface 21A of the resin layer 21. In addition, the metal foil-coated resin tape 20 can also have the metal foil 22 arranged on both the upper surface 21A and the lower surface 21B of the resin layer 21.

[0033] The resin contained in the resin layer 21 can be one or more selected from, for example, polyester resins such as polyethylene terephthalate (PET), polyolefin resins such as polypropylene (PP), and vinyl resins such as polyvinyl chloride (PVC). In addition to the various resins, the resin layer 21 may also contain additives.

[0034] The thickness of the resin layer 21 is not particularly limited, but it is preferably 10 μm or more. By making the thickness of the resin layer 21 10 μm or more, the mechanical strength and handling of the metal foil-attached resin tape 20 can be improved.

[0035] Furthermore, it is preferable that the thickness of the resin layer 21 be 500 μm or less. By making the thickness of the resin layer 21 500 μm or less, it becomes easier to wrap the metal foil-attached resin tape 20 around the twisted wire pair 100, and the shape of the shielded twisted wire pair 10 can be stabilized.

[0036] The material of the metal foil 22 is not particularly limited, but examples include one or more metal materials selected from copper, copper alloys, aluminum, aluminum alloys, etc. The metal foil 22 may be composed of metal foil of a single metal type, or it may be made up of two or more metal foils of different metal types laminated together. In addition, a non-metallic material, such as a protective film containing an organic material, may be placed on the surface of the metal foil, to the extent that it does not interfere with the noise shielding properties of the shielded twisted wire 10.

[0037] The thickness of the metal foil 22 is not particularly limited, but it is preferably between 1 μm and 30 μm. By making the thickness of the metal foil 22 1 μm or more, the noise shielding performance can be particularly enhanced. Furthermore, by making the thickness of the metal foil 22 30 μm or less, the flexibility of the resin tape with metal foil can be increased.

[0038] In the first shielding 131 of the shielded twisted wire 10 of this embodiment, it is preferable to position the first surface 20A, which is the surface on which the metal foil 22 of the resin tape 20 with metal foil is arranged, outward, that is, facing the second shielding 132, which will be described later.

[0039] Therefore, in the first shielding 131, the second surface 20B, which is the surface on which the resin layer 21 of the metal foil-covered resin tape 20 is arranged, can be positioned facing the twisted wires 100.

[0040] An adhesive layer can also be placed on the side of the metal foil-coated resin tape 20 that faces the twisted wire pair 100, i.e., the second side 20B. By placing an adhesive layer, the metal foil-coated resin tape 20 can be bonded to the twisted wire pair 100, thereby stabilizing the shape of the shielded twisted wire pair 10.

[0041] As shown in Figure 3, the first metal foil-attached resin tape, the metal foil-attached resin tape 20, can be spirally wrapped around the twisted wire 100 along its longitudinal direction to form the first shield 131. Note that in Figure 3, the cross-sectional structure of the twisted wire 100 and the retaining winding 12, which would normally be visible at the ends of the twisted wire 100 and their surroundings, is omitted. Also, a part of the first shield 131 has been peeled off to make the arrangement of the components clear, showing the retaining winding 12 exposed on the side. The first shield 131 can be positioned outside the twisted wire 100 and can be positioned to cover the outer surface of the twisted wire 100. When the retaining winding 12, which will be described later, is positioned on the outer surface of the twisted wire 100, the first shield 131 is positioned to cover the outer surface of the retaining winding 12, as shown in Figure 3.

[0042] The above explanation shows an example with a retaining coil 12, but the retaining coil 12 can be omitted.

[0043] When wrapping the first metal foil-attached resin tape around the twisted wire 100, it is preferable to overlap portions of adjacent first metal foil-attached resin tapes along the longitudinal direction of the twisted wire 100 so that the outer surface of the twisted wire 100 can be completely covered.

[0044] By spirally wrapping a first metal foil-attached resin tape around the twisted-pair wire 100 to form a first shield 131, the shielded twisted-pair wire 10 can be made to have basic characteristics required for wires that transmit signals in the high-frequency range, such as suppressing insertion loss. (2-2)Second shielding The second shield 132 may have a braided conductor.

[0045] As shown in Figure 4, the braided conductor 40 of the second shield 132 can have a braided structure formed by weaving metal strands 41 into a hollow cylindrical shape. Since the braided structure has excellent mechanical strength, the presence of a braided conductor in the second shield 132 enhances the noise shielding performance of the shielded twisted-pair wire 10 while also increasing its durability.

[0046] Figure 4 shows an enlarged view of a portion of the braided conductor 40 that forms the second shield 132. As shown in Figure 4, the braided conductor 40 can have a structure in which multiple metal strands 41, which are units 43, are braided together so as to intersect with each other, and a mesh 42 is present at the intersection. The number of units 43, which are multiple metal strands 41, in the braided conductor 40 may be denoted as the number of strands, and the number of metal strands 41 in the unit 43 may be denoted as the number of strands, etc.

[0047] The material of the metal strands 41 used in the braided conductor 40 of the second shield 132 is not particularly limited, but metal materials such as copper, copper alloys, aluminum, aluminum alloys, or materials with a plating applied to their surface, such as tin-plated soft copper, can be used. Soft copper can be preferably used as the copper.

[0048] The configuration of the braided conductor 40 of the second shield 132 is not particularly limited, but the braided conductor 40 of the second shield 132 preferably has a braiding density of 40% or more, more preferably 50% or more, and even more preferably 60% or more.

[0049] Braid density refers to the ratio of the area occupied by the metal strands 41 to the unit area of ​​the braided conductor 40. Therefore, the braid density can be calculated, for example, by the following procedure.

[0050] The braided conductor 40 is imaged using imaging means such as a camera, so as to include a square evaluation area where the length of one side is half the width of the electric wire. The width of the electric wire refers to the outer diameter of the twisted pair electric wire 100. The obtained image is binarized to calculate the area (A) of the metal strand portion within the evaluation area. Then, the braid density can be calculated from the area (B) of the evaluation area using the following formula (1).

[0051] Braid density (%)=A÷B×100 (1) By setting the braiding density to 40% or more, the noise shielding performance of the shielded twisted-pair electric wire 10 can be particularly enhanced.

[0052] There is no particular upper limit to the braid density, but it is preferable that the braid density be 95% or less, and more preferably 90% or less.

[0053] By limiting the braiding density to 95% or less, the cost of manufacturing the second shield 132 can be reduced, and productivity can be increased. (2-3) Third shielding The third shielding 133 may have a resin tape with a second metal foil.

[0054] By combining the first shield 131, the second shield 132, and the third shield 133 to form a shield 13, the electrical characteristics of the shielded twisted-pair wire 10 can be improved, and noise shielding performance can be enhanced. Therefore, a shielded twisted-pair wire 10 that is particularly suitable for use in high-frequency communications can be made.

[0055] As the metal foil-coated resin tape 20 that can be used for the second metal foil-coated resin tape, the same structure as that described for the first metal foil-coated resin tape can be used, so the explanation is omitted here.

[0056] Furthermore, the first metal foil-attached resin tape of the first shielding 131 and the second metal foil-attached resin tape of the third shielding 133 may have the same or different configurations.

[0057] In this embodiment, the shielded twisted-pair wire 10 has a third shield 133, which improves the noise shielding performance of the shielded twisted-pair wire 10 even when the braiding density of the second shield 132 is low. In this case, because the braiding density of the second shield is low, it is lightweight, flexible, and easy to handle.

[0058] The second metal foil-attached resin tape preferably covers the outer circumference of the second shielding 132 without any gaps, and the way it is wound is not particularly limited.

[0059] The second metal foil-covered resin tape of the third shielding 133 is preferably arranged vertically, that is, in a vertical arrangement. Vertical arrangement means that, as shown in Figure 5, the end 133A of the second metal foil-covered resin tape 20 of the third shielding 133, which is parallel to the longitudinal direction, is positioned along the central axis of the twisted wire pair 100, and the metal foil-covered resin tape is wrapped around the outer circumference of the twisted wire pair 100 so as to enclose it with its surface. By wrapping the second metal foil-covered resin tape so as to overlap around the outer circumference of the twisted wire pair 100, the outer surface of the twisted wire pair 100, specifically the second shielding 132, can be completely covered without any gaps.

[0060] Note that in Figure 5, the cross-sectional structures of the twisted wires 100, the retaining winding 12, the first shielding 131, and the second shielding 132, which would normally be visible at the ends of the twisted wires 100 and their surroundings, have been omitted. In addition, a portion of the third shielding 133 has been peeled off to make the arrangement of the components clear, and the second shielding 132 is shown exposed on the side.

[0061] The above explanation shows an example with a retaining coil 12, but the retaining coil 12 can be omitted.

[0062] By aligning the resin tape with the second metal foil of the third shield 133 vertically, the current flowing through the third shield 133 can be directed along the longitudinal direction of the shielded twisted-pair wire, thereby particularly enhancing the noise shielding performance of the shielded twisted-pair wire 10. Therefore, even with a low braiding density of the second shield 132, the noise shielding performance can be sufficiently enhanced. In this case, because the braiding density of the second shield is low, it can be made lightweight and easy to handle.

[0063] According to the inventors' research of the present invention, the insertion loss is smaller when "the first metal foil-attached resin tape is spirally wound around the first shielding 131 and the second metal foil-attached resin tape is vertically attached to the third shielding 133" compared to "the first metal foil-attached resin tape is vertically attached to the first shielding 131 and the second metal foil-attached resin tape is spirally wound around the third shielding 133".

[0064] Therefore, it was confirmed that the above combination is preferable for each layer constituting the shield 13 from the viewpoint of improving the electrical characteristics of the shielded twisted-pair electric wire 10. (2-4) Others It is preferable that the metal foil of the first metal foil-attached resin tape of the first shielding 131 in the shield 13 is in contact with the braided conductor of the second shielding 132. Furthermore, it is preferable that the braided conductor of the second shielding 132 is in contact with the metal foil of the second metal foil-attached resin tape of the third shielding 133. In other words, it is preferable that the metal foil of the first shielding 131, the braided conductor of the second shielding 132, and the metal foil of the third shielding 133 are electrically connected. As described above, by electrically connecting the metal foil of the first shielding 131, the braided conductor of the second shielding 132, and the metal foil of the third shielding 133, noise shielding performance can be improved.

[0065] (3) Outer covering The outer sheath 14 is an optional component, but the presence of the outer sheath 14 in the shielded twisted-pair wire 10 provides physical protection for the shield 13 and the twisted-pair wire 100. In particular, when the shielded twisted-pair wire 10 of this embodiment is used in automobiles, it is necessary to protect the shielded twisted-pair wire 10 from the effects of water. The outer sheath 14 also plays a role in preventing contact with water from affecting various characteristics of the shielded twisted-pair wire 10, such as characteristic impedance.

[0066] The outer sheath 14 may contain insulating material. The insulating material contained in the outer sheath 14 may contain resin, and the resin can be one or more selected from polyolefins such as polyethylene and polypropylene, polyvinyl chloride, polystyrene, polytetrafluoroethylene, polyphenylene sulfide, etc. In addition to the resin, the outer sheath 14 may also contain additives such as flame retardants as appropriate.

[0067] From the viewpoint of reducing the dielectric constant of the outer sheath 14, and in particular from the viewpoint of avoiding an excessive increase in dielectric constant even when exposed to high temperatures in an in-vehicle environment, it is preferable to use a resin with low molecular polarity as the resin contained in the outer sheath 14. For example, among those listed above, it is preferable to use polyolefin, which is a non-polar resin such as polypropylene. Furthermore, the outer sheath 14 may contain the same type of resin as the insulator 112 of the insulated wire 11, or it may contain a different type of resin. From the viewpoint of simplifying the overall structure and manufacturing process of the shielded twisted pair wire 10, it is preferable to use materials of the same type.

[0068] The thickness of the outer sheath 14 may be determined appropriately, taking into consideration the required protective performance. For example, from the viewpoint of obtaining sufficient protective performance, it is preferable that the thickness of the outer sheath 14 be 0.2 mm or more. On the other hand, from the viewpoint of avoiding the shielded twisted wire 10 becoming excessively large in diameter, it is preferable that the thickness of the outer sheath 14 be 1.0 mm or less. Furthermore, from the viewpoint of simplifying the structure, it is preferable that the outer sheath 14 consists of one layer of insulating material, but it may consist of multiple layers.

[0069] From the viewpoint of simplifying the structure of the shielded twisted-pair electric wire 10, it is preferable that the outer sheath 14 directly covers the outer circumference of the inner shield 13, but a layer made of another material may be provided between the two. For example, as described above, when a third shield 133 having a second metal foil-attached resin tape is arranged on the outer surface of the shield 13, an adhesive layer can be provided on the second metal foil-attached resin tape to bond the outer sheath 14 and the third shield 133. By providing the above adhesive layer, the third shield 133 can be removed at the same time as the outer sheath 14 at the end of the shielded twisted-pair electric wire 10, improving work efficiency. (4) Retaining winding The shielded twisted wire 10 of this embodiment may also have a retaining winding 12 that covers the outer surface of the twisted wire 100. The retaining winding 12 can be formed by winding a tape-like material spirally around the outer circumference of the twisted wire 100 along the longitudinal direction of the twisted wire 100.

[0070] The shielded twisted-pair wire 10 has a retaining winding 12, which helps to stabilize the shape and electrical characteristics of the twisted-pair wire 100.

[0071] The material of the retaining wrap 12 is not particularly limited, and one or more insulating materials selected from, for example, paper, nonwoven fabric, polyester or other resins can be used.

[0072] The retaining band 12 may consist of one layer or multiple layers of two or more.

[0073] An adhesive layer can also be placed on the surface of the retaining winding 12 that faces the twisted wire pair 100. By placing an adhesive layer, the retaining winding 12 can be bonded to the twisted wire pair 100, and the shape of the shielded twisted wire pair 10 can be stabilized. [Examples]

[0074] The present invention will be described with specific examples below, but it is not limited to these examples. (1) Evaluation method Ssd12 and Ssc12 were measured for the shielded twisted-pair wires prepared in each of the following experimental examples.

[0075] Ssd12 represents the differential mode noise radiation characteristic, while Ssc12 represents the common mode noise radiation characteristic. Therefore, when Ssd12 and Ssc12 are below a predetermined value, it means that the noise shielding performance is excellent.

[0076] The length of the shielded twisted-pair wire used for measuring Ssd12 and Ssc12 was set to 3m, and measurements were taken using a network analyzer. (2) Conditions for manufacturing shielded twisted-pair electric wires The conditions and results for each experimental example are described below. Experimental Examples 2 to 6 are examples, and Experimental Example 1 is a comparative example. [Experimental Example 1] A shielded twisted-pair electric wire 10 was manufactured having the cross-sectional structure shown in Figure 1, except that the shield 13 does not have a third shield 133. (1) Stranded wire 100 Two insulated wires 11 were twisted together so that the twisting pitch was 14 mm to form a paired twisted wire 100.

[0077] As shown in Table 1, each of the two insulated wires 11 used in the twisted wire 100 has a conductor 111 made by twisting together seven strands of conductor strands 111A, which are bare soft copper wires with an outer diameter of 0.16 mm and have not been coated with plating or the like, and a polypropylene insulator 112 that covers the conductor 111.

[0078] Table 1 shows the outer diameters of the conductor 111 and the insulator 112.

[0079] The outer diameter of the conductor 111 was evaluated using the following procedure. Within an arbitrary cross-section perpendicular to the longitudinal direction of the conductor 111, the outer diameter was measured using a micrometer along two orthogonal diameters of the conductor 111. The average of the measurements taken at these two locations was then taken as the outer diameter of the conductor 111. The outer diameters of the insulator 112, the conductor strands 111A, the metal strands 41 used for the second shielding described later, and the outer sheath 14 were measured in the same manner. (2) Retaining winding A polyester tape was spirally wrapped around the outer surface of the twisted wire 100 to form a retaining wrap 12. The width and thickness of the polyester tape used are shown in Table 1. (3) Shield A shield 13 having a first shield 131 and a second shield 132 is formed outside the twisted wire 100 and the retaining winding 12. (1st shielding) The first shielding 131 was formed by spirally wrapping a first metal foil-attached resin tape around the twisted wire pair 100, as shown in Figure 3. The first metal foil-attached resin tape used had the same cross-sectional structure as the metal foil-attached resin tape 20 shown in Figure 2, with the resin layer 21 being made of polyester and the metal foil 22 being aluminum foil. A metal foil-attached resin tape having this configuration is referred to as "Al-laminated polyester tape" in Table 1. The width and thickness of the first metal foil-attached resin tape are as shown in Table 1.

[0080] The first metal foil-covered resin tape, the metal foil-covered resin tape 20, was wrapped around the twisted wire 100 such that the second surface 20B, on which the resin layer 21 is placed, faced the twisted wire 100, and the first surface 20A, on which the metal foil 22 is placed, faced the second shield 132. (Second shielding) The second shield 132 has a braided conductor 40, as explained using Figure 4. The braided conductor 40 has a braided structure formed by weaving together tin-plated soft copper wires, which are metal strands 41, into a hollow cylindrical shape, as shown in Table 1. The outer diameter of the metal strands and the number of strands and dots in the braided structure are as shown in Table 1. The second shield 132 is positioned to be in contact with the metal foil 22 of the first metal foil-attached resin tape that the first shield 131 has. The braiding density of the second shield 132 was evaluated by the procedure described above and is shown in the density column of Table 1. (outer covering) An outer covering 14 was placed outside the second shielding 132. As shown in Table 1, the outer covering 14 was made of a polyethylene-based flame-retardant halogen-free resin, and its outer diameter was as shown in Table 1.

[0081] The obtained shielded twisted-pair wires were evaluated as described above. The evaluation results are shown in Figures 6A and 6B. Figure 6A shows the evaluation results for the fabricated shielded twisted-pair wire Ssd12, and Figure 6B shows the evaluation results for the fabricated shielded twisted-pair wire Ssc12. Reference lines A and B are shown together in the figures. [Experimental Examples 2-6] As shown in Table 1, a shielded twisted-pair electric wire 10 was fabricated and evaluated under the same conditions as in Experimental Example 1, except for a difference in the configuration of the shield 13.

[0082] Regarding the second shielding of Shield 13, the number of strands and braided structures were configured as shown in Table 1, and the braid density was set to the value shown in the "Density" column of Table 1.

[0083] Furthermore, the shield 13 was configured to also have a third shielding layer 133. The third shielding layer 133 was formed by placing a second metal foil-attached resin tape vertically outside the second shielding layer 132, as shown in Figure 5. The second metal foil-attached resin tape used had the same cross-sectional structure as the metal foil-attached resin tape 20 shown in Figure 2, with the resin layer 21 being made of polyester and the metal foil 22 being aluminum foil. The width and thickness of the second metal foil-attached resin tape are as shown in Table 1.

[0084] The second metal foil-attached resin tape, the metal foil-attached resin tape 20, was wrapped around the twisted wire 100 such that the first surface 20A, on which the metal foil 22 is placed, faces the second shielding 132, and the second surface 20B, on which the resin layer 21 is placed, is located on the outside.

[0085] The evaluation results are shown in Figures 7A to 11B.

[0086] Figures 7A, 8A, 9A, 10A, and 11A show the evaluation results for the shielded twisted-pair wires Ssd12 produced in Experimental Examples 2 to 6, respectively. The fact that the measured values ​​are distributed below reference line A in the figures confirms that the noise shielding performance is sufficient.

[0087] Figures 7B, 8B, 9B, 10B, and 11B show the evaluation results for the shielded twisted-pair wire Ssc12 fabricated in Experimental Examples 2 to 6, respectively. The fact that the measured values ​​are distributed below the reference line B in the figures confirms that the noise shielding performance is sufficient.

[0088] [Table 1] Comparing Figures 6A and 6B, which show the results of Experimental Example 1, with Figures 7A and 7B, which show the results of Experimental Example 2, it was confirmed that the measured values ​​in Experimental Example 2, which has a third shielding, are distributed in a region further away from the reference lines A and B than in Experimental Example 1, which does not have a third shielding. In other words, it was confirmed that the shielded twisted pair wire in Experimental Example 2, which has a third shielding, has superior noise shielding performance compared to the shielded twisted pair wire in Experimental Example 1, which does not have a third shielding.

[0089] Furthermore, the results from Experimental Examples 3 to 5 confirmed that by placing a third shield, it is possible to create a shielded twisted-pair wire with excellent noise shielding properties even if the braiding density of the braided conductor in the second shield is reduced. [Explanation of Symbols]

[0090] 10 Shielded twisted-pair wires 100-pair twisted wire 11 Insulated wires 111 Conductor 111A Conductor strand 112 Insulator 12 Retainer Wrap 13 Shields 131 1st shielding 132 2nd shielding 133 Third shield 133A End 14 Outer cover 20. Metal foil-coated resin tape (First metal foil-coated resin tape, Second metal foil-coated resin tape) 20A, Page 1 20B 2nd side 21 Resin layer 21A Top 21B Bottom side 22 Metal foil 40 Braided Conductors 41 Metal wire 42 stitches 43 units A reference line B Reference line

Claims

1. A twisted-pair wire made by twisting two insulated wires together, It has a shield that covers only the aforementioned twisted wires, The insulated wire has a conductor and an insulator covering the conductor. The shield has a first shield, a second shield, and a third shield in order from the position closest to the twisted wires. The first shielding has a first metal foil-attached resin tape that is spirally wrapped around the outside of the twisted-pair electric wires. The second shield has a braided conductor formed by weaving together multiple metal strands to create a hollow structure. The third shielding has a resin tape with a second metal foil, The metal foil of the first metal foil-attached resin tape and the braided conductor are in contact, and the braided conductor and the metal foil of the second metal foil-attached resin tape are in contact. A shielded twisted-pair electric wire to which the second metal foil-attached resin tape is attached vertically.

2. The shielded twisted-pair electric wire according to claim 1, wherein the braiding density of the braided conductor is 40% or more.

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