Communication Cables

Abstract

To provide a communication cable capable of preventing a formation of a crack potentially leading to a deterioration of shield performance, in a film-like noise shield material having a metal layer.SOLUTION: A communication cable 1 includes: a core wire 2 having a conductor 21 and an insulator layer 22 surrounding an outer periphery of the conductor 21; and a film-like shield 3 attached surrounding an outer periphery of the core wire 2 in a longitudinal direction. The film-like shield 3 includes: a metal matrix layer 32 composed of a metal layer; and a stripe member 33 being a linear or belt-like component closely adhered onto the metal matrix layer 32. The stripe member 33 is extended along an axial direction A1 of the core wire 2, and a plurality of the stripe members are arranged with intervals along a circumferential direction A2 of the core wire.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to communication wires. [Background technology]

[0002] In communication electric wires used in fields such as automobiles, a shield body having a metal layer made of copper, aluminum, an alloy containing these metals, or the like is sometimes arranged around the outer periphery of a core wire as a noise shielding layer for reducing the intrusion of noise from the outside and the emission of noise to the outside. For example, Patent Document 1 discloses a communication electric wire having a metal foil shield. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2009-146850 A [Patent Document 2] Japanese Utility Model Application Publication No. 03-112828 [Patent Document 3] JP 2002-329425 A [Patent Document 4] Japanese Utility Model Application Publication No. 63-146913 [Patent Document 5] Japanese Utility Model Application Publication No. 05-090739 Summary of the Invention [Problem to be solved by the invention]

[0004] In communication electric wires, higher shielding performance is more easily obtained when a film-type shield having a metal layer is arranged in a vertically attached state rather than in a horizontally wound state. However, when a vertically attached film-type shield is used, cracks may form in the metal layer of the film-type shield when the communication electric wire is repeatedly bent. Since bending involves bending the communication electric wire in the axial direction, cracks in the metal layer of the film-type shield are likely to form in a direction intersecting the axial direction, i.e., a direction perpendicular to the axial direction or a direction close to the axial direction. When cracks form in the metal layer of the film-type shield, the shielding performance is reduced, and there is a possibility that noise cannot be sufficiently shielded.

[0005] In particular, in the field of automobiles, with the development of autonomous driving technology, there is a demand for communication wires capable of transmitting large amounts of information at high speed, such as information required for outside-vehicle image recognition. As communication speeds increase, the effects of noise become more severe, so it is desirable to impart high shielding performance to communication wires. Therefore, it is preferable to suppress the formation of cracks due to bending as described above in film-type shields. However, wires arranged in parts that are repeatedly bent, such as inside the doors of automobiles, are in an environment where cracks are likely to form in the film-type shield in a direction intersecting the axial direction of the communication wire due to bending.

[0006] In view of the above, an object of the present invention is to provide a communication cable in a film-like noise shielding material having a metal layer, in which the formation of cracks that lead to a decrease in shielding performance is suppressed. [Means for solving the problem]

[0007] The communication wire according to the present disclosure comprises a core wire having a conductor and an insulating layer covering the outer periphery of the conductor, and a film-like shield vertically surrounding the outer periphery of the core wire, the film-like shield having a metal base layer composed of a metal layer and a stripe material which is a linear or band-like member adhered to the metal base layer, the stripe material extending along the axial direction of the core wire and being arranged at intervals along the circumferential direction of the core wire. Effect of the Invention

[0008] The communication electric wire according to the present disclosure is a communication electric wire in which the formation of cracks that lead to a decrease in shielding performance is suppressed in a film-like noise shielding material having a metal layer. [Brief description of the drawings]

[0009] [Figure 1] 1A and 1B are a perspective view and a cross-sectional view showing a communication wire according to a first embodiment of the present disclosure. [Diagram 2] FIG. 2 is a perspective view showing the configuration of a film shield included in the communication electric wire according to the first embodiment. [Diagram 3] 3A and 3B are a perspective view and a cross-sectional view showing a communication wire according to a second embodiment of the present disclosure. [Figure 4] FIG. 4 is a perspective view showing the configuration of a film shield included in the communication electric wire according to the second embodiment. [Diagram 5] 5A to 5C are side views showing the configuration of communication electric wires used in the evaluation of shielding performance, each with a different direction of the slits formed in the film shield: the slits are parallel to the axial direction of the core wire in sample A in Fig. 5A, oblique (45°) in sample B in Fig. 5B, and perpendicular in sample C in Fig. 5C. [Figure 6] FIG. 6 shows the results of evaluating the shielding performance of four types of communication wires. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] [Description of the embodiments of the present disclosure] First, an embodiment of the present disclosure will be described. The communication wire according to the present disclosure comprises a core wire having a conductor and an insulating layer covering the outer periphery of the conductor, and a film-like shield vertically surrounding the outer periphery of the core wire, the film-like shield having a metal base layer composed of a metal layer and a stripe material which is a linear or band-like member adhered to the metal base layer, the stripe material extending along the axial direction of the core wire and being arranged at intervals along the circumferential direction of the core wire.

[0011] In the above communication electric wire, the film-like shield arranged on the outer periphery of the core wire has a metal base layer, and functions as an electromagnetic wave shield to suppress the intrusion of noise into the core wire and the emission of noise from the core wire. A stripe material configured as a linear or band-like member is in close contact with the surface of the metal base layer of the film-like shield and is provided in a plurality of stripes along the circumferential direction of the core wire, so that cracks extending in a direction intersecting the axial direction of the core wire are unlikely to be formed in the metal base layer of the film-like shield. Even if a crack is formed in a direction intersecting the axial direction, it is limited to a short crack. Even if the communication electric wire is repeatedly bent, a long crack is unlikely to be formed in a direction intersecting the axial direction, so that the communication electric wire can maintain high shielding performance even in an environment where bending is likely to occur, such as inside an automobile. Even if a crack is formed in the metal base layer of the film-like shield during bending, it is likely to be a crack along the axial direction of the core wire. Even if a crack extending along the axial direction is formed, it is less likely to lead to a significant decrease in the shielding performance of the communication electric wire compared to a crack in a direction intersecting the axial direction.

[0012] Here, the communication electric wire is preferably configured as a coaxial electric wire and further includes a braided shield that surrounds the outside of the film shield and is made of a braided body of metal wires. Although a coaxial electric wire is susceptible to noise due to its structure, by providing the film shield on the outer periphery of the core wire, it has high shielding performance and can maintain the high shielding performance even if it is repeatedly bent. Furthermore, by providing a braided shield in addition to the film shield, the shielding performance is particularly improved.

[0013] The stripe material may be made of a material containing an organic polymer. This allows a film shield having the stripe material to be easily formed using a lightweight and inexpensive material. Furthermore, when a braided shield is disposed adjacent to the film shield, the metal base layer contacts the braided shield at the location where the stripe material is disposed via the organic polymer layer constituting the stripe material, so that the stripe material performs a buffering function. When the communication electric wire is bent, a large load is unlikely to be applied from the braided shield to the surface of the metal base layer, and the bending resistance of the communication electric wire is increased.

[0014] In this case, the stripe material may be made of a material containing a conductive polymer. This makes the entire surface of the film shield where the metal base layer and the stripe material are arranged conductive, resulting in high shielding performance. In addition, it is easy to ensure electrical continuity between the film shield and a conductive member, such as a braided shield, that is arranged over the film shield.

[0015] Alternatively, the stripe material may be made of metal wire or conductive fiber. In this case, the stripe material has high material strength, which increases the mechanical strength of the film shield. Even if a crack forms in the metal base layer, the conductive stripe material can function as a path for the return current to flow, thereby maintaining high shielding properties.

[0016] The film shield may further include a metal coating layer as a metal layer different from the metal base layer, and the stripe material may be sandwiched between the metal base layer and the metal coating layer. In this case, the stripe material is easily maintained on the surface of the metal base layer in a state in which it extends along the axial direction of the core wire and is arranged at a predetermined interval. In addition to the metal base layer, the metal coating layer also functions as a shielding body, contributing to improved shielding performance.

[0017] The film shield may further include a sheet-like polymer substrate containing an organic polymer, the metal base layer being formed on the surface of the polymer substrate, and the stripe material being disposed on the surface of the metal base layer opposite to the polymer substrate. By using a polymer substrate, the metal base layer can be formed as a thin metal film, which can be easily held stably. In addition, the strength and ease of handling of the film shield as a whole can be improved.

[0018] In this case, the communication electric wire has a braided shield composed of a braid of metal wires and surrounding the outer periphery of the core wire, and the film shield may be in contact with the braided shield on the surface opposite to the surface on which the polymer substrate is disposed. By disposing the braided shield in addition to the film shield in the communication electric wire, the shielding properties can be effectively improved. In this case, by bringing the surface of the film shield opposite to the surface on which the polymer substrate is disposed, i.e., the surface on which the stripe material is disposed on the surface of the metal base layer or the surface on which the metal coating layer is disposed, into contact with the braided shield, electrical continuity can be ensured between the film shield and the braided shield.

[0019] [Details of the embodiment of the present disclosure] Hereinafter, the communication wire according to the embodiment of the present disclosure will be described in detail with reference to the drawings. Hereinafter, the terms "parallel," "perpendicular," and the like, which express the shape and arrangement of the components, include not only the geometrically strict concept but also the range of error generally allowed for communication wires. For example, the angle includes an error of about ±10°.

[0020] [1] Communication cable according to the first embodiment 1A and 1B show the structure of a communication electric wire 1 according to a first embodiment of the present disclosure, in which Fig. 1A is a perspective view and Fig. 1B is a cross-sectional view cut perpendicular to the axial direction.

[0021] (Overall structure of communication cables) The communication wire 1 is configured as a coaxial wire. Specifically, the communication wire 1 includes a core wire 2 having a conductor 21 and an insulating layer 22 that covers the outer periphery of the conductor 21. A film shield 3 is provided on the outer periphery of the core wire 2. A braided shield 4 configured as a braided body made by braiding metal wires is provided on the outer periphery of the film shield 3. Furthermore, a sheath layer 5 is provided on the outer periphery of the braided shield 4.

[0022] The above-mentioned communication wire 1, which is configured as a coaxial wire having a film-like shield 3 and a braided shield 4 on the outer periphery of the core wire 2, can be suitably used for transmitting signals in a high frequency range of 1 GHz or more. However, the communication wire 1 according to the present disclosure is not limited to the above-mentioned structure, and may adopt a configuration according to the communication frequency and the purpose as long as the film-like shield 3 is provided surrounding the outer periphery of the core wire 2. For example, in the above embodiment, a single insulated wire having a conductor 21 and a coating layer 22 is used as the core wire 2, but multiple insulated wires may be used. Specifically, the core wire 2 can be configured so that a pair of insulated wires are twisted together or run in parallel to each other to transmit a differential signal. In addition, if the influence of noise is not so large, the braided shield 4 may be omitted. Furthermore, in the above embodiment, each of the layers described above is formed by directly contacting the outer periphery of the inner constituent layer, but the communication wire 1 may appropriately include constituent layers other than the layers described above. Hereinafter, each of the components of the coaxial communication cable 1 exemplified above will be described.

[0023] The core wire 2 is a signal line that transmits electric signals in the communication cable 1, and includes a conductor 21 and an insulating layer 22 that covers the outer circumference of the conductor 21. The materials that make up the conductor 21 and the insulating layer 22 are not particularly limited. As the material that makes up the conductor 21, various metal materials can be used, but it is preferable to use copper or a copper alloy in terms of high conductivity. The conductor 21 may be configured as a single wire, but it is preferable to configure it as a twisted wire in which a plurality of wires (for example, seven wires) are twisted together in terms of increasing flexibility when bending. The insulating layer 22 insulates the conductor 21 in the core wire 2, and is made of a material containing an organic polymer. The type of organic polymer is not particularly limited, and examples thereof include olefin-based polymers such as polyolefin and olefin-based copolymers, halogen-based polymers such as polyvinyl chloride, various engineering plastics, elastomers, rubbers, and the like. In addition to the organic polymer, the insulating layer 22 may contain additives as appropriate.

[0024] The film shield 3, which will be described in detail later, is configured as a composite layered with a polymer substrate 31, a metal base layer 32, and a row of a plurality of stripes 33. The film shield 3 functions as a noise shielding member due to the presence of the metal base layer 32. In other words, it prevents external electromagnetic waves from penetrating the core wire 2 and causing noise in the signal transmitted through the core wire 2, and also prevents electromagnetic waves generated by the signal transmitted through the core wire 2 from being released to the outside and becoming a noise source.

[0025] The film shield 3 is disposed vertically around the outer periphery of the core wire 2. In other words, the film shield 3 is disposed along the circumferential direction of the core wire 2, wrapping the outer periphery of the core wire 2 with the surface of the film shield 3. By disposing the film shield 3 vertically, higher shielding performance can be obtained compared to a configuration in which the film shield 3 is disposed horizontally (a configuration in which a tape-shaped film shield is spirally wound around the outer periphery of the core wire 2).

[0026] The front and back directions when the film shield 3 is arranged around the core wire 2 are not limited, but when the braided shield 4 is used in combination with the film shield 3, it is preferable to arrange the film shield 3 so that the surface opposite to the surface on which the polymer substrate 31 is arranged is in contact with the braided shield 4. In other words, the surface of the metal base layer 32 on which the stripe material 33 is arranged should be oriented toward the braided shield 4. In the illustrated embodiment, the surface of the polymer substrate 31 should be oriented inward, and the surface of the metal base layer 32 on which the stripe material 33 is arranged should be oriented outward. This ensures electrical continuity between the braided shield 4 and the surface of the metal base layer 32 that is not covered by the stripe material 33 and is exposed.

[0027] The braided shield 4 is configured as a braided body formed by interweaving a plurality of metal wires into a hollow tubular shape. Examples of the metal wires constituting the braided shield 4 include metal materials such as copper, copper alloys, aluminum, and aluminum alloys, and metal materials whose surfaces are plated with tin or the like. Although the braided shield 4 is not essential to the communication electric wire 1, providing it functions as a noise shielding member together with the metal base layer 32 of the film shield 3. The braided shield 4 may be provided on the outer side or the inner side of the film shield 3, but it is preferable to provide it on the outer side as shown in the figure from the viewpoint of reducing signal loss, etc.

[0028] The sheath layer 5 is disposed as the outermost layer of the communication electric wire 1, and plays a role of protecting the core wire 2, the film-like shield 3, and the braided shield 4 disposed inside. The sheath layer 5 is made of a material containing an organic polymer. The type of organic polymer is not particularly limited, and examples thereof include olefin-based polymers such as polyolefins and olefin-based copolymers, halogen-based polymers such as polyvinyl chloride, various engineering plastics, elastomers, rubbers, and the like. In addition to the organic polymer, the sheath layer 5 may contain an additive as appropriate. Furthermore, the sheath layer 5 may contain a powdered magnetic material, particularly a soft magnetic material. Then, in the communication electric wire 1, the sheath layer 5 performs a noise shielding function together with the film-like shield 3 and the braided shield 4. Examples of soft magnetic materials include metal oxides such as ferrite, iron (pure iron or iron containing a small amount of carbon), various magnetic stainless steels, and alloys such as Fe-Ni alloys (permalloys).

[0029] (Details of the film shield) As shown in the overall views of the communication cable 1 in Figures 1A and 1B, and as shown in the perspective view of the structure of the film shield 3 in Figure 2, the film shield 3 is configured as a composite having a polymer substrate 31, a metal base layer 32, and a row of multiple stripes 33 laminated in this order.

[0030] The polymer substrate 31 is a sheet-like member made of a material containing an organic polymer. The polymer substrate 31 is not essential for the film shield 3, but by using the polymer substrate 31, the metal base layer 32 as a thin metal layer can be easily formed and stably held. In addition, the mechanical strength and handling of the film shield 3 can be improved. The organic polymer constituting the polymer substrate 31 is not particularly limited, but examples include polyolefins such as polyethylene terephthalate (PET) and polypropylene (PP), polyvinyl chloride (PVC), and the like. In particular, PET can be preferably used from the viewpoint of high mechanical strength, etc. The polymer substrate 31 may appropriately contain various additives in addition to the organic polymer.

[0031] The metal base layer 32 is configured as a continuous metal layer covering one surface of the polymer substrate 31, and serves as a shielding member for shielding electromagnetic noise by electrostatic shielding in the communication electric wire 1. The type of metal constituting the metal base layer 32 is not particularly limited, but metals commonly used as shielding materials such as copper, copper alloys, aluminum, aluminum alloys, silver, silver alloys, gold, and gold alloys can be suitably used in this embodiment as well. In particular, it is preferable to use copper or copper alloys. The metal base layer 32 may be configured by stacking layers of multiple metal materials. The metal base layer 32 is integrally bonded to the surface of the polymer substrate 31 by vapor deposition, plating, adhesion, or the like.

[0032] The stripe material 33 is configured as a linear or belt-like member. In the film shield 3, a plurality of stripe materials 33 are arranged in close contact with the surface of the metal base layer 32, that is, the surface of the metal base layer 32 opposite to the surface in contact with the polymer substrate 31. Here, the term "linear or belt-like" for the stripe material 33 refers to a shape in which the dimension in the width direction (direction A2) is smaller than the dimension in the longitudinal direction (direction A1). In the case of a linear shape, the dimension in the thickness direction is equal to or larger than the dimension in the width direction, and in the case of a belt-like shape, the dimension in the thickness direction is smaller than the dimension in the width direction. In the first embodiment, it is particularly preferable that the stripe material 33 is a belt-like member.

[0033] The material of the stripe material 33 is not particularly limited as long as it is configured as a linear or belt-like member, but it is preferable that the material has higher bending resistance than the material of the metal base layer 32. In other words, it is preferable to configure the stripe material 33 using a material that is less likely to cause damage such as cracks or breaks than the metal base layer 32 when the communication electric cable 1 is bent.

[0034] In the communication cable 1 according to the first embodiment, the stripe material 33 is made of a material containing an organic polymer. Preferably, the stripe material 33 is made of an organic polymer as a main component. The organic polymer constituting the stripe material 33 is not particularly limited, but examples thereof include polyolefins such as PET and PP, thermoplastic resins such as PVC, and various hardening resins. In particular, PET can be preferably used from the viewpoint of high mechanical strength. The stripe material 33 may contain various additives in addition to the organic polymer. Furthermore, the stripe material 33 is preferably made of a material containing a conductive polymer and has conductivity as a whole. In this case, the material constituting the stripe material 33 may be an organic polymer itself made of a conductive polymer, or may be made conductive by mixing various organic polymers with a conductive additive. The multiple stripe materials 33 may all be made of the same material, or multiple stripe materials 33 made of different materials may be mixed.

[0035] The stripe material 33 extends along the axial direction (the longitudinal direction in which the core wire 2 extends) A1 of the core wire 2 on the surface of the metal base layer 32. The multiple stripe materials 33 are arranged at intervals from one another along the circumferential direction A2 of the core wire 2, i.e., along a direction perpendicular to the axial direction A1. The multiple stripe materials 33 are parallel to one another.

[0036] In the film-like shield 3, a plurality of stripes 33 are arranged on the surface of the metal base layer 32 along the axial direction A1 of the core wire 2, so that cracks that cross the locations where the stripes 33 are arranged are unlikely to occur in the metal base layer 32. This is because the presence of the stripes 33 prevents cracks from occurring and propagating. Therefore, in the metal base layer 32, cracks that extend in a direction intersecting the axial direction A1 of the core wire 2, that is, in the direction A2 perpendicular to the axial direction A1 or in a direction close to the direction, are unlikely to form. Even if a crack does form that extends in a direction intersecting the axial direction A1, the crack is kept short.

[0037] If the stripe material 33 is not arranged on the surface of the metal base layer 32, cracks are likely to occur in the metal base layer 32 at the bent points when the communication cable is repeatedly bent. Since bending occurs along the axial direction A1 of the core wire 2, a force is applied to the metal base layer 32 in a direction that bends and stretches it along the axial direction A1, and the application of the force makes it likely that cracks will occur in a direction intersecting the axial direction A1. The cracks that occur in the metal base layer 32 reduce the shielding performance of the film-like shield 3. In particular, the shielding performance is significantly reduced as the cracks extend in the direction A2 perpendicular to the axial direction A1 or in a direction close to the direction A2. This is because the path of the return current that flows along the axial direction A1 on the surface of the metal base layer 32 is cut off by the cracks, and the return current flows around the cracks, making it impossible to cancel out the noise. In recent years, communication wires installed in automobiles are required to have high noise shielding performance as frequencies become higher. However, communication wires routed in door sections and other areas inside an automobile are frequently subjected to loads that bend them in the axial direction, making them more susceptible to the formation of cracks that cross the axial direction, which can reduce noise shielding performance.

[0038] In contrast, in the communication electric wire 1 according to this embodiment, even if it is repeatedly bent, cracks extending across the stripe material 33 and in a direction intersecting the axial direction A1 are unlikely to occur due to the stripe material 33 being disposed on the metal base layer 32 of the film-like shield 3, so that high shielding performance is maintained for a long period of time even in an environment where the cable is bent. Therefore, the communication electric wire 1 according to this embodiment can be suitably used in places such as inside an automobile that are likely to be subjected to loads in the bending direction and where high noise shielding performance is required.

[0039] In the film-like shield 3, cracks extending in a direction along the axial direction A1 of the core wire 2, i.e., in a direction parallel to or close to the axial direction A1, can be formed in the metal base layer 32 even when the stripe material 33 is provided. However, as shown in the following examples, cracks along the axial direction A1 do not reduce the shielding performance of the metal base layer 32 as much as cracks intersecting the axial direction A1. This is because cracks along the axial direction A1 are unlikely to have a significant effect on the path of the return current flowing through the metal base layer 32. When the communication electric cable 1 is repeatedly bent, cracks are formed in the metal base layer 32, which can relieve the stress applied to the metal base layer 32. Therefore, in the metal base layer 32 of the film-like shield 3, if, during bending, the presence of the stripe material 33 suppresses the formation of cracks in the metal base layer 32 in a direction intersecting the axial direction A1, while allowing cracks to form along the axial direction A1, it is possible to reduce the mechanical load associated with bending of the metal base layer 32 by stress relaxation while avoiding a significant decrease in shielding performance due to crack formation.

[0040] Furthermore, in the communication electric wire 1 according to the present embodiment, the stripe material 33 provided on the film shield 3 is made of a material containing an organic polymer, which not only suppresses the deterioration of shielding performance due to bending, but also reduces the load applied to the film shield 3 from adjacent members due to bending, thereby improving the bending resistance of the communication electric wire 1. Specifically, the organic polymer layer of the stripe material 33 is interposed between the metal base layer 32 and the braided shield 4, so that the stripe material 33 exhibits a buffer function. In other words, the load that the metal base layer 32 receives from the braided shield 4 due to contact with the braided shield 4 when bending, and the distortion of the metal base layer 32 due to the load are alleviated by the presence of the stripe material 33 formed as an organic polymer layer, and the metal base layer 32 is less likely to suffer damage such as excessive deformation and cracks due to bending.

[0041] In the film-like shield 3, from the viewpoint of efficiently suppressing the formation of cracks intersecting the axial direction A1 by the stripe material 33 and from the viewpoint of obtaining the effect at each position in the circumferential direction A2, the arrangement interval d1 of the stripe material 33 is preferably 1 mm or less in length and 15% or less of the circumferential length (the length of a straight line that goes around the surface of the metal base layer 32 along the circumferential direction A2 of the core wire 2). Since the smaller the arrangement interval d1 of the stripe material 33, the higher the effect of crack suppression, no lower limit is set for the arrangement interval d1 of the stripe material 33. However, from the viewpoint of, for example, making it easy to arrange the stripe material 33 on the surface of the metal base layer 32, it is preferable that the arrangement interval d1 is 0.4 mm or more in length and 5% or more of the circumferential length. The stripe materials 33 do not necessarily need to be arranged at equal intervals along the circumferential direction A2, but from the viewpoint of obtaining the same crack suppression effect at each position in the circumferential direction A2, it is preferable to arrange them at equal intervals with an error of about ±10% or less.

[0042] The coverage rate, which is the area of ​​the region where the stripe material 33 is provided (the area of ​​the region covered by the stripe material 33) out of the total surface area of ​​the metal base layer 32, is preferably 40% or more from the viewpoint of effectively suppressing the formation of cracks intersecting the axial direction A1. On the other hand, the coverage rate is preferably 80% or less from the viewpoint of sufficiently ensuring electrical continuity with the braided shield 4 on the surface of the metal base layer 32 that is not covered by the stripe material 33. Note that if the stripe material 33 contains a conductive polymer and is conductive as a whole, electrical continuity with the braided shield 4 can be obtained even in the area covered by the stripe material 33.

[0043] The method of adhering the stripe material 33 containing an organic polymer to the surface of the metal base layer 32 is not particularly limited, but it is preferable to use adhesion. In this case, when the constituent material of the stripe material 33 itself is made of a thermoplastic resin or various curable resins that are adhesive to the metal base layer 32, the stripe material 33 may be formed by disposing a liquid resin material in a predetermined stripe pattern on the surface of the metal base layer 32 and then solidifying it. On the other hand, when the constituent material of the stripe material 33 does not itself exhibit adhesiveness to the metal base layer 32 or when it is difficult to dispose the material on the surface of the metal base layer 32 in a liquid state, the stripe material 33 may be adhered to the surface of the metal base layer 32 using an adhesive or pressure-sensitive adhesive different from the constituent material of the stripe material 33. When the stripe material 33 contains a conductive polymer and is conductive as a whole, it is preferable to use an adhesive or pressure-sensitive adhesive that is also conductive. When the stripe material 33 is bonded to the surface of the metal base material 32 using an adhesive or pressure-sensitive adhesive, adjacent stripe materials 33 arranged parallel to each other at a specified interval may be connected by cross materials arranged crossing the extension direction of the stripe material 33 (axial direction A1) in order to improve the handleability of the stripe material 33, etc.; however, from the standpoint of making it easier to tolerate the formation of cracks along the axial direction A1 on the surface of the metal base layer 32 and making it easier to ensure conductivity between the metal base layer 32 and the braided shield 4, it is preferable to keep the area occupied by the cross materials on the surface of the metal base layer 32 to 20% or less of the area occupied by the stripe material 33.

[0044] In the film shield 3 constituting the communication electric wire 1 according to the first embodiment, from the viewpoint of structural simplicity and light weight, it is preferable that no other layer is provided on the surface on which the stripe material 33 is disposed on the surface of the metal base layer 32. However, similarly to the film shield 3' constituting the communication electric wire 1' according to the second embodiment of the present disclosure described next, a metal coating layer 35 may be provided on the surface of the metal base layer 32 on which the stripe material 33 is provided, and the stripe material 33 may be sandwiched between the metal base layer 32 and the metal coating layer 35.

[0045] [2] Communication cable according to the second embodiment Next, a communication electric wire according to a second embodiment of the present disclosure will be described. Figures 3A and 3B show the structure of a communication electric wire 1' according to the second embodiment of the present disclosure. Figure 3A is a perspective view, and Figure 3B is a cross-sectional view cut perpendicular to the axial direction. Figure 4 shows, in a perspective view, the structure of a film-like shield 3' included in the communication electric wire 1' according to the second embodiment. Hereinafter, components common to the communication electric wire 1 according to the first embodiment will be indicated by corresponding reference numerals in the drawings, and description thereof will be omitted.

[0046] The communication electric wire 1' according to the second embodiment has a similar configuration to the communication electric wire 1 according to the first embodiment, but includes a film-like shield 3' having a different configuration from that of the first embodiment. The film-like shield 3' of the communication electric wire 1' according to the second embodiment is configured as a composite in which a polymer substrate 31, a metal base layer 32, a stripe material 34, and a metal coating layer 35 are laminated in this order. Of these, the polymer substrate 31 and the metal coating layer 35 are optional components, but are preferably included. When the polymer substrate 31 is included, the film-like shield 3' is arranged so as to contact the braided shield 4 on the side of the communication electric wire 1' opposite to the side on which the polymer substrate 31 is arranged, that is, the side on which the stripe material 34 and the metal coating layer 35 are arranged.

[0047] In the film-like shield 3' in the second embodiment, the polymer substrate 31 and the metal base layer 32 can be the same as those in the film-like shield 3 in the first embodiment. However, in this embodiment, the stripe material 34 is configured as a conductive linear member. More specifically, the stripe material 34 is configured from a metal wire or a conductive fiber. The specific constituent material of the stripe material 34 is not particularly limited, but in the case of a metal wire, a metal material such as copper, a copper alloy, aluminum, an aluminum alloy, or a metal material whose surface is plated with tin or the like can be suitably used. The metal wire may be a single wire or a twisted wire, but a single wire is preferable from the viewpoint of ensuring a small diameter. On the other hand, in the case where the stripe material 34 is a conductive fiber, the composition is not particularly limited as long as it is a flexible wire other than a metal wire, but examples of the material include a material in which a powder of a conductive material such as a metal or a carbon material is mixed into an organic polymer to form a fiber, and a material in which a metal layer is provided on the outer periphery of an organic polymer fiber.

[0048] The metal coating layer 35 is configured as a continuous metal layer and plays a role in adhering the stripe material 34 to the metal base layer 32. The metal coating layer 35 also functions as a noise shielding material together with the metal base layer 32. As with the metal base layer 32, the material constituting the metal coating layer 35 may suitably be copper, copper alloy, aluminum, aluminum alloy, silver, silver alloy, gold, gold alloy, or the like. In particular, it is preferable to use copper or a copper alloy. As with the metal base layer 32, the metal coating layer 35 may be compounded with a substrate made of an organic polymer. However, when the braided shield 4 is provided on the outer periphery of the film-like shield 3', from the viewpoint of ensuring the conduction between the metal coating layer 35 and the braided shield 4, it is preferable that the metal coating layer 35 is configured as an independent metal foil that is not compounded with a substrate.

[0049] In the film-like shield 3', the linear stripe material 34 is sandwiched between the metal base layer 32 and the metal coating layer 35, and is thereby adhered closely to the metal base layer 32. In addition to or instead of being sandwiched by the metal coating layer 35, the stripe material 34 may be adhered to the surface of the metal base layer 32 via an adhesive or a pressure-sensitive adhesive. In this case, it is preferable that the adhesive or pressure-sensitive adhesive is also conductive. The stripe material 34 may be adhered to the metal coating layer 35 in addition to the metal base layer 32. The metal base layer 32 and the metal coating layer 35 may be joined to each other in a portion where the stripe material 34 is not arranged.

[0050] In this embodiment, as in the first embodiment, a plurality of stripes 34 are arranged along the axial direction A1 of the core wire 2 in the film shield 3'. This prevents cracks from forming on the surface of the metal base layer 32 that cross the axial direction A1 even if the communication electric wire 1' is bent. Even if a crack crossing the axial direction A1 is formed, the crack is kept short. As a result, high shielding performance is maintained even if the communication electric wire 1' is repeatedly bent. Furthermore, since the stripes 34 are made of a conductive material, even if a crack is formed in the metal base layer 32 due to bending or the like, the stripes 34 function as a path for the return current, so that the film shield 3' as a whole can maintain its shielding performance. Furthermore, since the stripes 34 have high material strength, they also function as a reinforcing material and play a role in increasing the mechanical strength of the film shield 3'. In particular, when the stripes 34 are made of metal wire, they can effectively function as a return path and a reinforcing material.

[0051] In this embodiment, from the same viewpoint as in the first embodiment, the spacing d1 of the stripes 34 in the film shield 3' is preferably 1 mm or less in length and 15% or less of the circumference. On the other hand, there is no particular lower limit set for the spacing d1 of the stripes 34, but it is preferable to set it to, for example, 0.4 mm or more in length and 5% or more of the circumference. The stripes 34 do not necessarily have to be arranged at equal intervals along the circumferential direction A2, but it is preferable to arrange them at equal intervals with an error of about ±10% or less. Furthermore, from the viewpoint of obtaining a sufficient crack suppression effect and functioning as a reinforcing material, the wire diameter of the stripes 34 is 0.1 On the other hand, in order to ensure sufficient flexibility, the wire diameter of the stripe material 34 is preferably 0.6 In the present embodiment, adjacent stripe materials 34 arranged parallel to each other with a predetermined interval may be connected by cross materials, but the area of ​​the cross materials on the surface of the metal base layer 32 should be kept to 20% or less of the area of ​​the stripe materials 34. EXAMPLES

[0052] Examples are shown below. Note that the present invention is not limited to these examples. Here, the relationship between the direction of cracks formed in the metal base layer of the film shield and the effect on the shielding performance was investigated.

[0053] (Sample Preparation) Four types of coaxial communication wires were prepared as samples A to D. For each of the four types, the conductor (conductor cross-sectional area: 0.61 mm 2 The film shield, braided shield, and sheath layer were placed in that order around the core wire, which had its outer circumference covered with an insulating layer. The film shield was made by bonding a copper metal base layer (thickness: 9 μm) to one side of a PET substrate (thickness: 12 μm), and was placed around the core wire with the metal base layer facing outward.

[0054] The communication electric wires of samples A to D differ from one another in the presence or absence of slits in the film shield and in the arrangement angle. As shown in Figs. 5A to 5C, in samples A to C, slits were formed on the surface of the metal base layer of the film shield as a model of a crack. In all samples, the slits were formed in the metal base layer. layer and an opening penetrating the PET substrate in the thickness direction. The length of the slit (d2 in the figure) was 1 mm, and the width was the minimum value that could be processed. Samples A to C differ from each other in the arrangement angle of the slits, with sample A being arranged parallel to the axial direction of the core wire, sample B being arranged diagonally at an angle of 45° to the axial direction of the core wire, and sample C being arranged perpendicular to the axial direction of the core wire. In all samples, the interval between the slits (d3 in the figure) was 2 mm. For reference, sample D had no slits in the film shield.

[0055] (Test Method) Each of the communication electric wires of samples A to D was cut to a length of 1200 mm, and the shielding attenuation was measured in the range up to 3 GHz. The measurement was performed according to the test method based on IEC 62153-4-4.

[0056] (Test Results) Figure 6 shows the measurement results of shielding attenuation for samples A to D. The horizontal axis shows the measurement frequency and the vertical axis shows the shielding attenuation (unit: dB), with the measured value at each frequency positioned lower on the vertical axis indicating higher shielding performance.

[0057] As shown in Figure 6, sample D, which has no slits in the film shield, has the highest shielding performance. Sample A, which has slits formed parallel to the axial direction of the core wire, has lower shielding performance compared to sample D, which has no slits, but the amount of decrease is small. In particular, in the frequency range above about 2 GHz, the shielding attenuation is almost the same as that of sample D. In contrast, samples B and C, which have slits formed at an angle to the axial direction, have significantly lower shielding performance compared to sample D. In particular, the decrease in shielding performance is significant for sample C, which has slits formed perpendicular to the axial direction.

[0058] From the above, it can be seen that when slits are formed in the metal base layer of a film shield arranged on a communication cable, the closer the direction in which the slits extend is to a direction perpendicular to the axial direction of the core wire, the greater the deterioration in shielding performance. If the direction in which the slits extend is parallel to the axial direction, even if the slits are formed, the effect on shielding performance is kept very small. In particular, in the high frequency range, the effect on shielding performance is small, and high shielding performance is maintained despite the formation of the slits.

[0059] The present invention is not limited to the above-described embodiment, and various modifications are possible without departing from the spirit of the present invention. [Explanation of symbols]

[0060] 1,1' Communication cable 2 core wire 21 Conductor 22 Insulating layer 3,3' Film Shield 31 Polymer substrates 32 Metal base layer 33,34 Stripe material 35 Metal coating layer 4 Braided Shield 5. Sheath layer A1 Axial direction of core wire A2 Circumferential direction of core wire d1 Spacing of stripes d2 Slit length d3 Slit spacing

Claims

1. A core wire having a conductor and an insulating layer covering the outer periphery of the conductor; a film-like shield that vertically surrounds the outer periphery of the core wire, The film shield is A metal base layer composed of a metal layer; a stripe material which is a linear or belt-like member in close contact with the metal base layer and is made of a material containing a substance which is made conductive by mixing an organic polymer selected from polyethylene terephthalate, polyolefin, and polyvinyl chloride with a conductive additive; the stripe material extends along an axial direction of the core wire, and a plurality of stripes are arranged at intervals along a circumferential direction of the core wire, A communication cable in which a constituent material of the stripe material does not exhibit adhesiveness to the metal base layer by itself, and the stripe material is adhered to the surface of the metal base layer by an adhesive or pressure-sensitive adhesive different from the constituent material of the stripe material.

2. A core wire having a conductor and an insulating layer covering the outer periphery of the conductor; a film-like shield that vertically surrounds the outer periphery of the core wire, The film shield is A metal base layer composed of a metal layer; a stripe material which is a linear or belt-like member in close contact with the metal base layer and is made of an organic polymer selected from polyethylene terephthalate, polyolefin, and polyvinyl chloride, or a material containing a substance made conductive by mixing the organic polymer with a conductive additive; a metal coating layer which is a metal layer different from the metal base layer; the stripe material extends along the axial direction of the core wire, and a plurality of stripes are arranged at intervals along the circumferential direction of the core wire; and sandwiched between the metal base layer and the metal coating layer; A communication cable in which a constituent material of the stripe material does not exhibit adhesiveness to the metal base layer by itself, and the stripe material is adhered to the surface of the metal base layer by an adhesive or pressure-sensitive adhesive different from the constituent material of the stripe material.

3. A core wire having a conductor and an insulating layer covering the outer periphery of the conductor; a film-like shield that vertically surrounds the outer periphery of the core wire; a braided shield that is made of a braid of metal wires and that surrounds the outside of the film-like shield; The film shield is A metal base layer composed of a metal layer; a stripe material which is a linear or belt-like member adhered closely to the metal base layer and is made of an organic polymer selected from polyethylene terephthalate, polyolefin, and polyvinyl chloride, or a material containing a substance made conductive by mixing the organic polymer with a conductive additive; the stripe material extends along an axial direction of the core wire, and a plurality of stripes are arranged at intervals along a circumferential direction of the core wire, a constituent material of the stripe material does not exhibit adhesiveness to the metal base layer by itself, and the stripe material is adhered to the surface of the metal base layer by an adhesive or pressure-sensitive adhesive different from the constituent material of the stripe material; A communication cable configured as a coaxial cable.

4. A core wire having a conductor and an insulating layer covering the outer periphery of the conductor; a film-like shield that vertically surrounds the outer periphery of the core wire; a braided shield that is made of a braid of metal wires and surrounds an outer periphery of the core wire; The film shield is A sheet-like polymer substrate containing an organic polymer; A metal base layer formed on the surface of the polymer substrate, the metal base layer being made of a metal layer; a stripe material which is a linear or band-like member that is made in close contact with the metal base layer and is made of an organic polymer selected from polyethylene terephthalate, polyolefin, and polyvinyl chloride, or a material containing a substance that has been made conductive by mixing the organic polymer with a conductive additive, and is disposed on a surface of the metal base layer opposite to the polymer substrate; the stripe material extends along an axial direction of the core wire, and a plurality of stripes are arranged at intervals along a circumferential direction of the core wire, a constituent material of the stripe material does not exhibit adhesiveness to the metal base layer by itself, and the stripe material is adhered to the surface of the metal base layer by an adhesive or pressure-sensitive adhesive different from the constituent material of the stripe material; The communication wire, wherein the film shield contacts the braided shield on a surface opposite to the surface on which the polymer substrate is disposed.

5. A core wire having a conductor and an insulating layer covering the outer periphery of the conductor; a film-like shield that vertically surrounds the outer periphery of the core wire, The film shield is A metal base layer composed of a metal layer; a stripe material which is a linear or belt-like member adhered closely to the metal base layer and is made of an organic polymer selected from polyethylene terephthalate, polyolefin, and polyvinyl chloride, or a material containing a substance made conductive by mixing the organic polymer with a conductive additive; The stripe material extends along the axial direction of the core wire, and a plurality of stripes are arranged at intervals of 1 mm or less along the circumferential direction of the core wire, A communication cable in which a constituent material of the stripe material does not exhibit adhesiveness to the metal base layer by itself, and the stripe material is adhered to the surface of the metal base layer by an adhesive or pressure-sensitive adhesive different from the constituent material of the stripe material.

6. The film shield further includes a sheet-like polymer substrate including an organic polymer; The metal base layer is formed on a surface of the polymer substrate, The communication cable according to claim 1 , wherein the stripe material is disposed on a surface of the metal base layer opposite to the polymer substrate.

7. 7. The communication cable according to claim 1, wherein the stripe material is made of a material containing polyethylene terephthalate.

8. 8. The communication cable according to claim 1, wherein in the film shield, no other layer is provided on a surface of the metal base layer on which the stripe material is disposed.

Images