Optical-electric composite cable and method for manufacturing the same

An optical-electric composite cable includes a cable unit, at least one metal wire, and a sheath. The cable unit includes at least one optical fiber and a twisted pair wire twisted with the at least one optical fiber. The at least one metal wire is disposed around the cable unit. The sheath surrounds the cable unit and the at least one metal wire.

This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2020-029435, filed on Feb. 25, 2020, the entire contents of which are incorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates to an optical-electric composite cable and a method for manufacturing an optical-electric composite cable.

BACKGROUND

JP2013-218916A discloses an example of an optical-electric composite cable having optical fibers and metal wires (electrical wires). The optical-electric composite cable includes a unit in which the optical fibers are bundled up in a ribbon shape and an outer circumference thereof is surrounded by a tube-shaped resin. The metal wires are disposed to surround the unit in the optical-electric composite cable. JP2014-078435A, JP2012-053121A, JP2018-185982A, and JP2004-265780A each disclose another example of an optical-electric composite cable.

SUMMARY

The present disclosure provides an optical-electric composite cable. The optical-electric composite cable includes a cable unit, at least one metal wire, and a sheath. The cable unit includes at least one optical fiber and a twisted pair wire twisted with the at least one optical fiber. The at least one metal wire is disposed around the cable unit. The sheath surrounds the cable unit and the at least one metal wire.

The present disclosure provides a method for manufacturing an optical-electric composite cable. The manufacturing method includes forming a cable unit by twisting at least one optical fiber and a twisted pair wire, disposing at least one metal wire around the cable unit, and forming a sheath to surround the cable unit and the at least one metal wire.

TECHNICAL PROBLEM

The optical-electric composite cable described in JP2013-218916A employs a configuration in which the metal wires are disposed around the optical fiber unit disposed at a center. When a twisted pair wire is added to this configuration, it is conceivable to dispose the twisted pair wire around the optical fiber unit together with other metal wires. Since an outer diameter of the twisted pair wire is larger than an outer diameter of a general metal wire, a portion at which the twisted pair wire is positioned bulges outward significantly compared to portions at which the metal wires are positioned. Therefore, when the twisted pair wire is applied as it is to the conventional configuration, a shape of the optical-electric composite cable can be distorted or a size thereof may increase.

Advantageous Effects of Invention

According to the present disclosure, it is possible to provide an optical-electric composite cable which is thin and has a satisfactory external appearance while including a twisted pair wire and a method for manufacturing the same.

Solution to Problem

Details of embodiments of the present disclosure will be listed and described. An optical-electric composite cable according to one embodiment of the present disclosure includes a cable unit, at least one metal wire, and a sheath. The cable unit includes at least one optical fiber and a twisted pair wire twisted with the at least one optical fiber. The at least one metal wire is disposed around the cable unit. The sheath surrounds the cable unit and the at least one metal wire.

In the above optical-electric composite cable, the optical fiber and the twisted pair wire are twisted together to form the cable unit, and the metal wire is disposed around the cable unit. That is, it is configured such that the twisted pair wire is disposed on an inward side from a position at which the metal wire is disposed in the optical-electric composite cable. In this case, the twisted pair wire does not protrude significantly to the outside of the optical-electric composite cable, and thus distorted bulging is suppressed. Thus, an optical-electric composite cable can have a satisfactory external appearance. In addition, the twisted pair wire is disposed by effectively utilizing a region close to the optical fiber, thereby a thin optical-electric composite cable can be formed. Therefore, according to the present embodiment, it is possible to realize an optical-electric composite cable which is thin and has a satisfactory external appearance while including a twisted pair wire.

As one embodiment, the cable unit may be disposed at substantially a center of the sheath. According to this aspect, it is possible to realize an optical-electric composite cable which is thin as a whole and has a satisfactory external appearance by utilizing a region around the cable unit in a well-balanced manner.

As one embodiment, the at least optical fiber may includes a plurality of optical fibers, and the cable unit may include a first tape wound around the plurality of optical fibers. According to this aspect, the plurality of optical fibers are bundled up with each other by the first tape. In a manufacturing process of the optical-electric composite cable, it is possible to prevent loosened optical fibers from being sandwiched between the twisted pair wire and being damaged, and thus stabilizing and improving a manufacturing efficiency of the optical-electric composite cable can be achieved. In this embodiment, the first tape may be spirally wound around the plurality of optical fibers in a direction in which the cable unit extends.

As one embodiment, the first tape may be a resin tape and may be formed of polyethylene terephthalate having a thickness of 50 μm or more and 500 μm or less. According to this aspect, since the first tape is formed of polyethylene terephthalate having a thickness of 50 μm or more and has a sufficient strength, the first tape can be prevented from being torn when it is wound around the optical fibers. Since the first tape has a thickness of 500 μm or less, the optical-electric composite cable becoming thicker by an amount of that of the first tape can be prevented.

As one embodiment, the cable unit may include a second tape wound around the at least one optical fiber and the twisted pair wire. According to this aspect, the optical fiber and the twisted pair wire are bundled up and not separated by the second tape that is wound around the cable unit. Thus, a trouble in which the optical fiber or the twisted pair wire that is loosened becomes entangled in the manufacturing apparatus during manufacture of the optical-electric composite cable can be prevented, and manufacturing efficiency of the optical-electric composite cable can be stabilized. In this case, the tape may be formed of a composite material containing a metal material and a synthetic resin. According to this aspect, the second tape containing a metal material functions as a shield and can block noise entering the twisted pair wire from the outside of the optical-electric composite cable. Therefore, communication using the optical-electric composite cable can be stabilized. In this embodiment, the second tape may contain at least one of a copper foil and an aluminum foil, and a polyethylene terephthalate resin.

As one embodiment, the second tape may be spirally wound around the at least one optical fiber and the twisted pair wire in a direction in which the cable unit extends. The second tape may be wound such that winding portions thereof adjacent to each other are partially overlapped. Also, the second tape may be flat between a point in contact with the twisted pair wire and a point in contact with the first tape wound around the at least one optical fiber.

As one embodiment, the cable unit may include a drain wire which is disposed to be sandwiched between the twisted pair wire and the second tape. In this embodiment, the drain wire may be a conducting wire made of a metal.

As one embodiment, the cable unit may include a tensile strength fiber which extends linearly in a direction in which the cable unit extends on an inner side thereof. According to this aspect, the tensile strength fiber can prevent the optical fiber from being stretched and broken. In this embodiment, the tensile strength fiber may be disposed in at least one region of a region adjacent to the optical fiber, a region between the optical fiber and the twisted pair wire, a region between a pair of metal wires constituting the twisted pair wire, and a region between the twisted pair wire and the drain wire.

A method for manufacturing an optical-electric composite cable according to one embodiment includes, forming a cable unit by twisting at least one optical fiber and a twisted pair wire, disposing at least one metal wire around the cable unit, and forming a sheath to surround the cable unit and the at least one metal wire.

According to this manufacturing method, the optical fiber and the twisted pair wire are twisted into a unit, and the metal wire is disposed around the unit. Thus, the twisted pair wire does not protrude significantly to the outside of the optical-electric composite cable, and thus the optical-electric composite cable in which distorted bulging is suppressed can be manufactured. Since it is not necessary to provide a tube-shaped resin into which a bundle of the optical fibers is inserted, a thin optical-electric composite cable can be formed.

As one embodiment of the above-described manufacturing method, the at least one optical fiber may includes a plurality of optical fibers, and the forming of the cable unit may include forming an optical fiber bundle by winding a resin tape around the plurality of optical fibers. Also, the forming of the cable unit may include winding a composite tape containing a metal material and a synthetic resin around the at least one optical fiber and the twisted pair wire.

DETAILED DESCRIPTION

Specific examples of an optical-electric composite cable and a method for manufacturing the same according to the present disclosure will be described below with reference to the drawings. The present disclosure is not limited to these examples and is defined by the scope of the claims and is intended to include meanings equivalent to the claims and all modified examples within the scope. In the description of the drawings, the same elements will be denoted by the same reference signs, and duplicate description thereof will be omitted.

FIG. 1is a cross-sectional view of an optical-electric composite cable1according to one embodiment.FIG. 1illustrates a cross section obtained when the optical-electric composite cable1is cut in a direction perpendicular to a central axis direction. The optical-electric composite cable1includes a cable unit10, a plurality of metal wires30, an intervening string32, a sheath40, and a metal braid42.

The cable unit10is a bundle of cables including optical fibers and a twisted pair wire, and is housed inside the sheath40. A detailed configuration of the cable unit10will be described with reference toFIG. 2.

FIG. 2is a cross-sectional view of the cable unit10included in the optical-electric composite cable1. As illustrated inFIG. 2, the cable unit10includes a plurality of optical fibers12, a resin tape14, a twisted pair wire20, a drain wire22, a tensile strength fiber24, and a composite tape26.

The optical fibers12are each an optical fiber in which an outer side of a bare optical fiber is coated with an ultraviolet curable resin, a nylon resin, or the like. The optical fiber12may have a diameter of, for example, 0.25 mm or more and 0.9 mm or less. As an example in the present embodiment, the optical-electric composite cable1includes eight optical fibers12, but the present disclosure is not limited thereto. The number of optical fibers12included in the optical-electric composite cable1can be one or more. Generally, the optical-electric composite cable1may include an even number of optical fibers12.

The resin tape14is a tape wound around the plurality of optical fibers12(seeFIG. 5) and is, for example, spirally wound to be continuous in a direction in which the optical-electric composite cable1extends. The resin tape14may be wound such that end portions of adjacent winding portions of the tape overlap each other or may be wound such that a slight gap is formed between end portions of adjacent winding portions of the tape. The resin tape14bundles up the plurality of optical fibers12. The resin tape14is formed of a synthetic resin and may be formed of, for example, a polyethylene terephthalate (PET) resin. The resin tape may have a thickness of, for example, 50 μm or more and 500 μm or less.

The twisted pair wire20is a cable formed by twisting a pair of metal wires21together at a predetermined pitch. The twisted pair wire20is used for transmitting and receiving electrical signals or the like between electronic devices connected to each other by the optical-electric composite cable1. Each of the pair of metal wires21constituting one twisted pair wire20includes a metal conducting wire21aand an insulating sheath21bcovering the metal conducting wire21a. The metal conducting wire21amay be constituted by, for example, a single wire made of a copper wire plated with tin or a copper alloy, or a conductor obtained by twisting a plurality (for example, seven) of single wires made of a copper wire plated with tin or a copper alloy together. The metal conducting wire21amay have an outer diameter of, for example, 0.3 mm or more and 0.65 mm or less. A material of the sheath21bmay be, for example, polyvinyl chloride or polyethylene. The sheath21bmay have a thickness of, for example, 0.1 mm or more and 0.23 mm or less, and an outer diameter of 0.6 mm or more and 1.1 mm or less.

The drain wire22is a ground wiring for the composite tape26that functions as a shield. The drain wire22is disposed to be sandwiched between the twisted pair wire20and the composite tape26. The drain wire22is constituted by, for example, bundling bare metal wires.

The tensile strength fiber24is a fiber that extends in a direction in which the cable unit10extends. The tensile strength fiber24is positioned inside the composite tape26and is disposed to extend linearly without twisting. The tensile strength fiber24is disposed in, for example, a region adjacent to the optical fibers12(the resin tape14), a region between the optical fibers12(the resin tape14) and the twisted pair wire20, a region between the pair of metal wires21constituting the twisted pair wire20, or a region between the twisted pair wire20and drain wire22. The tensile strength fiber24has a tensile strength, and may be, for example, a synthetic fiber of polyamide (e.g. aramid fiber). The tensile strength fiber24can be disposed as linearly as possible to effectively exhibit a tensile strength. When the tensile strength fiber24is disposed near the optical fibers12, breakage of the optical fibers12is prevented.

The composite tape26is a composite tape wound around the plurality of optical fibers12, the twisted pair wire20, and the drain wire22. When the composite tape26is caused to function as a shield layer, the composite tape26is formed of a composite material containing a metal material and a synthetic resin (plastic material). As an example, the composite tape26may be a metal resin tape in which a copper foil or an aluminum foil is formed on a resin tape formed of polyethylene terephthalate (PET) resin. When the composite tape26is formed of a material containing a metal material, the composite tape26functions as a shield for the twisted pair wire20housed inside.

Referring toFIG. 1again, a position of the cable unit10in the optical-electric composite cable1will be described. The cable unit10is disposed substantially at a center of the sheath40. Here, “the cable unit10being disposed substantially at a center of the sheath40” indicates a case in which the cable unit10is disposed so that a central axis of the sheath40is inside an outer edge of the cable unit10(on an inner side of the composite tape26in the present embodiment) in a cross section of the optical-electric composite cable1illustrated inFIG. 1. That is, a central axis of the cable unit10does not necessarily have to coincide with the central axis of the sheath40.

An internal structure of the optical-electric composite cable1will be described with reference toFIG. 1. The plurality of metal wires30are disposed around the cable unit10. Each of the metal wires30is a cable in which an outer side of the metal conducting wire is covered with an insulating sheath. Each of the metal wire30is used for supplying electric power, transmitting and receiving an electric signal, or the like between electronic devices connected to each other by the optical-electric composite cable1. In the present embodiment, nine metal wires30are disposed, but the number of metal wires30can be one or more. Although the metal wires30having different outer diameter sizes are disposed in the embodiment, outer diameter sizes of the metal wires30are arbitrary, and all the metal wires30may have the same outer diameter size. Even at a largest outer diameter, the metal wire30has, for example, an outer diameter of 0.5 mm or more and 1.5 mm or less. The metal wire30has an outer diameter smaller than a range in which the twisted pair wire20is twisted around the central axis, that is, a range defined by an outer diameter of the composite tape26in the present embodiment. In other words, an outer diameter of the cable unit10is larger than an outer diameter of the metal wire30.

The intervening string32is disposed on an outer side of the cable unit10between the metal wires30different from each other. The intervening string32is used to fill voids generated between the metal wires30, and prevents a positional deviation of the metal wires30inside the optical-electric composite cable1. As the intervening string32, for example, PP yarn made of polypropylene that has been subjected to a low shrinkage treatment may be used.

The sheath40surrounds the cable unit10and the plurality of metal wires30, and protects the entire optical-electric composite cable1. The sheath40is formed in a cylindrical shape to house the cable unit10and the metal wires30therein. A material of the sheath40may be, for example, polyvinyl chloride (PVC), polyethylene, or an ethylene-vinyl acetate copolymer resin. The sheath40may have, for example, a thickness of 0.1 mm or more and 0.5 mm or less, and an outer diameter of 2 mm or more and 10 mm or less.

The metal braid42is further provided between the plurality of metal wires30and the sheath40. The metal braid42functions as a shield that blocks electromagnetic noise entering the metal wires30and the cable unit10from the outside, and enables a stable communication by the optical-electric composite cable1. The metal braid42may be one in which, for example, a metal conducting wire such as a single wire made of a copper wire plated with tin or a copper alloy is braided. The metal braid42may have a thickness of, for example, about 0.1 mm.

Next, a method for manufacturing the optical-electric composite cable1will be described with reference toFIGS. 3 to 6.FIG. 3is a flowchart showing a method for manufacturing the optical-electric composite cable1.

First, the resin tape14is wound around the plurality of optical fibers12to form the plurality of optical fibers12into one member which is an optical fiber bundle16(step S10).FIG. 4illustrates an apparatus50for winding the resin tape14around the optical fibers12. The apparatus50includes a fiber supply unit52, a tape supply unit54, and a winding unit56.

The fiber supply unit52includes a plurality of reels52aaround each of which the optical fiber12is wound. The number of reels52aincluded in the fiber supply unit52corresponds to the number of optical fibers12housed in the optical-electric composite cable1. In the present embodiment, for example, the fiber supply unit52includes eight reels52a, but illustration of some reels52ais omitted inFIG. 4. The fiber supply unit52sends the optical fibers12from each of the reels52ato the tape supply unit54. A dancer roller may be provided between the fiber supply unit52and the tape supply unit54in the apparatus50to pull the optical fibers12with a predetermined tension to remove flexure.

The tape supply unit54winds the resin tape14around the plurality of optical fibers12.FIG. 5illustrates a method of winding the resin tape14around the plurality of optical fibers12. As illustrated inFIG. 5, the resin tape14is spirally wound around the plurality of optical fibers12in the present embodiment. At this time, the resin tape14may be wound to be partially overlapped with an adjacent winding portion thereof so that the entire surface of the plurality of optical fibers12bundled up together is covered. The resin tape14may be wound with a gap provided between winding portions of the resin tape14adjacent to each other so that parts of surfaces of the optical fibers12is exposed to the outside. Hereinafter, a bundle of the plurality of optical fibers12around which the resin tape14is wound is referred to as “optical fiber bundle16.”

When it is completed to wind the resin tape14around the optical fibers12, the optical fiber bundle16is sent to the winding unit56illustrated inFIG. 4. The winding unit56includes a reel and winds the sent optical fiber bundle16using the reel. Thereby, step S10is completed.

Next, the optical fiber bundle16(the plurality of optical fibers12) and the twisted pair wire20are twisted together (step S11), and then, the composite tape26is wound around the cable unit10(step S12). Step S11and step S12will be described with reference toFIG. 6.FIG. 6is a view illustrating an apparatus60for manufacturing the cable unit10. The apparatus60includes a cable supply unit62, a fiber supply unit64, a tape supply unit66, and a winding unit68.

The cable supply unit62includes reels62a,62b, and62c. The optical fiber bundle16is wound around the reel62a. The twisted pair wire20is wound around the reel62b. The drain wire22is wound around the reel62c.

The optical fiber bundle16, the twisted pair wire20, and the drain wire22are respectively sent from the reels62a,62b, and62cto the tape supply unit66. The sent optical fiber bundle16and twisted pair wire20are twisted together at a predetermined pitch. For example, the optical fiber bundle16and the twisted pair wire20may be twisted together by rotating the cable supply unit62at a predetermined speed with an axis in a direction from the cable supply unit62toward the tape supply unit66(direction from the right side to the left side inFIG. 6) as a rotation axis. The drain wire22may be additionally twisted together or may be disposed to extend linearly.

The fiber supply unit64includes a plurality of reels64a. The tensile strength fiber24is wound around each of the reels64a. The tensile strength fiber24is sent from the reel64ato the tape supply unit66. The tensile strength fiber24is bundled up with the optical fiber bundle16, the twisted pair wire20, and the drain wire22in the process of reaching the tape supply unit66. However, the tensile strength fiber24is disposed to extend linearly without being twisted with the optical fiber bundle16or the like.

A dancer roller may be provided between the cable supply unit62and the tape supply unit66in the apparatus60to pull the optical fiber bundle16, the twisted pair wire20, and the drain wire22with a predetermined tension to remove flexure. A dancer roller may be provided between the fiber supply unit64and the tape supply unit66in the apparatus60to pull the respective tensile strength fibers24with a predetermined tension to remove flexure.

The tape supply unit66winds the composite tape26around the optical fiber bundle16, the twisted pair wire20, the drain wire22, and the tensile strength fibers24. At this time, the optical fiber bundle16, the twisted pair wire20, the drain wire22, and the tensile strength fibers24may be bundled up, and the composite tape26may be spirally wound around the bundle in the same manner as in the winding of the resin tape14illustrated inFIG. 5. In order for the composite tape26that is formed containing a metal material to function as a shield, the composite tape26is wound such that winding portions thereof adjacent to each other are partially overlapped to cover the entire surface of the optical fiber bundle16and the twisted pair wire20. That is, the composite tape26is wound so that there is no gap between winding portions thereof.

When the optical fiber bundle16, the twisted pair wire20, the drain wire22, and the tensile strength fibers24are wound by the composite tape26, the cable unit10is completed. The completed cable unit10is sent to the winding unit68illustrated inFIG. 6. The winding unit68includes a reel and winds the sent cable unit10with the reel. As described above, step S11and step S12end.

Next, the plurality of metal wires30are twisted together around the cable unit10(step S13). As illustrated inFIG. 1, the plurality of metal wires30having different outer diameters are twisted together to surround the cable unit10. In order to fill voids generated between the metal wires30, a predetermined amount of the intervening string32is twisted around the cable unit10together with the metal wires30.

Next, when step S13ends, the metal braid42and the sheath40are formed on an outer side of the metal wires30or the like (step S14). Specifically, the metal braid42is wound around the plurality of metal wires30, and then the sheath40is formed using extrusion molding. As described above, the optical-electric composite cable1has been manufactured.

As described above, according to the optical-electric composite cable1, the optical fibers12and the twisted pair wire20are twisted together to form the cable unit10, and the metal wires30are disposed around the cable unit10. That is, the optical-electric composite cable1is configured such that the twisted pair wire20is disposed on an inward side from positions at which the metal wires30are disposed in the optical-electric composite cable1. In this configuration, the twisted pair wire20does not protrude significantly to the outside of the optical-electric composite cable1, and thus distorted bulging is suppressed. Thus, the optical-electric composite cable1can have a satisfactory external appearance. In addition, the twisted pair wire20is disposed by effectively utilizing a region close to the optical fibers12, thereby the optical-electric composite cable1can be thin. Therefore, the optical-electric composite cable1which is thin and has a satisfactory external appearance can be realized while including the twisted pair wire20.

According to the optical-electric composite cable1, the cable unit10is disposed substantially at the center of the sheath40. According to this configuration, the optical-electric composite cable1can be thin as a whole and have a satisfactory external appearance by utilizing a region around the cable unit10in a well-balanced manner.

According to the optical-electric composite cable1, the plurality of optical fibers12are provided, and the cable unit10includes the resin tape14wound around the plurality of optical fibers12. According to this configuration, the plurality of optical fibers12are bundled up with each other by the resin tape14. Thus, in the manufacturing process of the optical-electric composite cable1, it is possible to prevent loosened optical fibers12from being sandwiched between the twisted pair wire20and being damaged. Therefore, manufacturing efficiency of the optical-electric composite cable1can be stabilized and improved.

According to the optical-electric composite cable1, the resin tape14is formed of polyethylene terephthalate having a thickness of 50 μm or more and 500 μm or less. According to this configuration, the resin tape14is formed of polyethylene terephthalate having a thickness of 50 μm or more and has a sufficient strength, thereby the resin tape14can be prevented from being torn when it is wound around the optical fibers12. In addition, the resin tape14has a thickness of 500 μm or less, thereby the optical-electric composite cable1becoming thicker by an amount of that of the resin tape14can be prevented.

According to the optical-electric composite cable1according to the present embodiment, the cable unit10includes the composite tape26wound around the optical fibers12and the twisted pair wire20.

According to this configuration, the optical fibers12and the twisted pair wire20are bundled up and not separated by the composite tape26that is wound around the cable unit10. Thus, a trouble in which the optical fiber12or the twisted pair wire20that is loosened becomes entangled in the manufacturing apparatus during manufacture of the optical-electric composite cable1can be prevented. Therefore, manufacturing efficiency of the optical-electric composite cable1can be stabilized. In this configuration, the composite tape26may be formed of a composite material containing a metal material and a synthetic resin. According to this configuration, the composite tape26containing a metal material functions as a shield to block noise entering the twisted pair wire20from the outside of the optical-electric composite cable1. Therefore, a communication using the optical-electric composite cable1can be stable.

According to the optical-electric composite cable1of the present embodiment, the cable unit10includes the tensile strength fiber24extending linearly in a direction in which the cable unit10extends. According to this configuration, the tensile strength fiber24can prevent the optical fibers12from being stretched and broken.

According to the method for manufacturing the optical-electric composite cable1of the present embodiment, the optical fibers12and the twisted pair wire20are twisted together into a unit, and the metal wires30are disposed around the cable unit10. Thus, the twisted pair wire20does not protrude significantly to the outside of the optical-electric composite cable1, thereby the optical-electric composite cable1in which distorted bulging is suppressed can be manufactured. In addition, it is not necessary to provide a tube-shaped resin into which a bundle of the optical fibers12is inserted, thereby the thin optical-electric composite cable1can be formed.

Modified Example

A modified example of the cable unit10will be described with reference toFIG. 7.FIG. 7is a cross-sectional view of a cable unit10A according to the modified example. In the following description, differences from the embodiments described above with reference toFIG. 2will be mainly described, and description of common points may be omitted.

The cable unit10A includes the plurality of optical fibers12and the resin tape14wound around the optical fibers12. In the embodiment illustrated inFIG. 2, in the cross-sectional view of the cable unit10, two rows of the optical fibers12with four in a row are disposed side by side substantially in parallel. Thus, a cross-sectional shape of the resin tape14surrounding the optical fibers12has a flat elliptical shape. On the other hand, in the optical fibers12of the cable unit10A according to the present modified example, the other optical fibers12are positioned to surround one optical fiber12in a cross-sectional view of the cable unit10A. Thus, the cross-sectional shape of the resin tape14has a shape that is more like a circle than that of the embodiment illustrated inFIG. 2.

The cable unit10A includes the composite tape26wound around the optical fibers12and the twisted pair wire20. In the cross-sectional view of the cable unit10A, two metal wires21constituting the twisted pair wire20and the optical fiber bundle16are disposed to be positioned at vertices of a triangle. Thus, the composite tape26is wound to have a substantially triangular shape in a cross-sectional view. In the composite tape26, a region connecting the twisted pair wire20and the optical fiber bundle16is provided substantially flat. On the other hand, the drain wire22is disposed between the two metal wires constituting the twisted pair wire20and the composite tape26. Thus, in the composite tape26, a region connecting the two metal wires constituting the twisted pair wire20is provided to bulge outward to draw an arc.

Similarly to the resin tape14illustrated inFIG. 5, the composite tape26is spirally wound around the optical fiber bundle16and the twisted pair wire20. At this time, the composite tape26is wound to be partially overlapped so that the entire surface of the optical fiber bundle16and the twisted pair wire20is covered. Thus, as illustrated in the cross-sectional view ofFIG. 7, the composite tape26is positioned to partially overlap on an outer surface of the optical fiber bundle16(the same applies toFIG. 1but is omitted).

The cable unit10A includes the tensile strength fibers24. In the present modified example, the tensile strength fibers24are disposed not only in a space between the optical fibers12and the twisted pair wire20, but also in a space between the twisted pair wire20and the drain wire22and a space between the twisted pair wire20and the composite tape26. The tensile strength fibers24are not limited to the above-described spaces and may also be disposed in other spaces in the composite tape26.

As in the present modified example, when the region connecting the twisted pair wire20and the optical fiber bundle16in the composite tape26is configured to be substantially flat, the cable unit10A can prevents from being thicker even when the composite tape26is provided. That is, a shape of the cable unit10A can be made even smaller than the aspect illustrated inFIG. 1. Thus, according to this modified example, the optical-electric composite cable1can be even thinner and have a satisfactory external appearance.

When the composite tape26is wound to be partially overlapped as in the present modified example, the entire surface of the twisted pair wire20can be covered without a gap, and noise can be blocked more reliably by the composite tape26. In the present modified example, the tensile strength fibers24are disposed in a plurality of spaces in the composite tape26. Thus, even when a tensile force is applied to the optical fibers12, the tensile strength fibers24can further prevent breakage or the like due to the tensile force.

While the embodiments and the examples of the present disclosure have been described in detail above, the present disclosure is not limited to the above-described embodiments and examples, and can be applied to various embodiments or examples. Outer diameters and thicknesses of the above-described constituent members or the number of optical fibers or metal wires are merely examples, and the present disclosure is not limited thereto.