Optical cable laying method

An object of the present disclosure is to provide a method of laying an optical cable that is capable of laying and removing the optical cable in a stable place without civil engineering works. To achieve the above-mentioned object, a method of laying an optical cable according to the present disclosure includes laying the optical cable and two laying strips on a road surface or a wall surface so that the optical cable is sandwiched between side surfaces of the two laying strips.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a 371 U.S. National Phase of International Application No. PCT/JP2020/021890, filed on Jun. 3, 2020. The entire disclosure of the above application is incorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates to a method of laying an optical cable.

BACKGROUND ART

Optical cables are used as transmission media for information communications. When the optical cables are laid outdoors, for example, an overhead wiring technology or an underground wiring technology is used. The overhead wiring technology is a wiring technology in which utility poles are built in advance on the ground and the optical cables are installed on the utility poles. The underground wiring technology is a wiring technology in which pipelines are buried underground in advance and the optical cables are laid in the pipelines.

Up to now, for lying new optical cables, the optical cables have been additionally laid in the area where metallic cables for communication have been already laid in most cases. In these cases, since fundamental equipment such as utility poles and pipelines has already been built, the optical cables can be economically laid without new civil engineering works. The reason is that the location where communication demand arises is similar to the location where the existing metallic cables have been wired, and thus the optical cables can be additionally laid without constructing new fundamental equipment.

To widely deploy, for example, antennas for mobile phones, the demand to lay optical fibers has recently arisen even in areas where fundamental equipment has not been built. Even when fundamental equipment has been built, the demand to provide new wiring arises on structures such as road lamps on roads instead of houses and buildings. These demands involve large investment to build additional fundamental equipment. For economical wiring of the optical cables, it is desirable to lay the optical cables without civil engineering works as much as possible.

To simplify civil engineering works, an optical cable that can be directly buried without using a pipeline has been proposed (see Patent Literature 1, for example). Alternatively, a method of laying an optical cable has also been proposed in which a groove is provided in a paved road surface and the optical cable is laid in the groove (see Non-Patent Literature 1, for example).

CITATION LIST

Patent Literature

Non-Patent Literature 1: Strain Sensing of an In-Road FTTH Field Trial and Implications for Network Reliability, Proc. of IWCS (2019)

SUMMARY OF THE INVENTION

Technical Problem

Unfortunately, although eliminating the need for burying pipelines or building utility poles, these methods involve digging up the ground for a length long enough to lay the optical cables or excavating the road surfaces paved with asphalt or concrete. Such civil engineering works are difficult to be performed by human power, and are large-scale ones such that heavy machinery is used.

When the optical cables are wired, connection units need to be provided for extending or branching the optical cables. Such connection units are generally accommodated in housings such as closures. When optical cables are laid according to the above-mentioned prior art, certain spaces for housing these closures need to be secured. Furthermore, when the optical cables are pulled up from the underground to the ground, spaces for protecting pull-up ports are required. These spaces must be prepared before the optical cables are laid.

The optical cables to be laid later need to have extra-length portions for future connection and branching. To protect the extra-length portions of the optical cables, boxes for accommodating the extra-length portions need to be provided. Since being installed on the ground, the box may be an obstructive factor for road traffic.

To ensure stable communication, the optical cables need to be laid in stable places. Furthermore, when being no longer needed, the optical cables are desirably removed without civil engineering works, as in installation.

The present disclosure is intended to solve the above-mentioned problems, and it is an object of the present disclosure to provide a method of laying an optical cable that is capable of laying and removing the optical cable in a stable place without civil engineering works. It is another object of the present disclosure to provide a laying strip that enables an optical cable to be laid and removed in a stable place without civil engineering works.

Means for Solving the Problem

To achieve the above-mentioned object, a method of laying an optical cable according to the present disclosure includes embedding the optical cable in at least two laying strips that are laid so that their side surfaces are in contact with a road surface or a wall surface.

Specifically, a method of laying an optical cable according to the present disclosure includes laying the optical cable and two laying strips on a road surface or a wall surface so that the optical cable is sandwiched between side surfaces of the two laying strips.

The method of laying the optical cable according to the present disclosure includes taking a preventive measure to prevent a distance between the side surfaces of the two laying strips facing each other from being enlarged.

For example, taking the preventive measure may be, with the side surfaces of the two laying strips between which the optical cable is sandwiched facing each other, engaging respective concave-convex shaped portions, apart from potions in contact with the optical cable, included in the side surfaces of the two laying strips.

For example, taking the preventive measure may be, with the side surfaces of the two laying strips between which the optical cable is sandwiched facing each other, thrusting tips of staples across the side surfaces of the two laying strips.

The method of laying the optical cable according to the present disclosure may contain the following:in laying the laying strips,a part of the laying strips is cut out to form a space for accommodating a connection unit of the optical cable, anda tray, in which the connection unit is to be arranged, is provided at a bottom of the space, and,in laying the optical cable,the optical cable is introduced into the tray and the connection unit is formed, andthe connection unit is accommodated in the tray, and an open side of the space is then covered with a lid.

The method of laying the optical cable according to the present disclosure may contain the following:a space for accommodating a connection unit of the optical cable is formed in advance in the laying strips,in laying the laying strips,a tray, in which the connection unit is to be arranged, is provided at a bottom of the space, and,in laying the optical cable,the optical cable is introduced into the tray and the connection unit is formed, andthe connection unit is accommodated in the tray, and an open side of the space is then covered with a lid.

The method of laying the optical cable according to the present disclosure may include the following:the laying strips have a perforated line to form a space for accommodating a connection unit of the optical cable,in laying the laying strips,the laying strips are cut using the perforated line to form the space, in which the connection unit is to be installed, and a tray, in which the connection unit is to be arranged, is then provided at a bottom of the space, and,in laying the optical cable,the optical cable is introduced into the tray and the connection unit is formed, andthe connection unit is accommodated in the tray, and an open side of the space is then covered with a lid.

A laying strip according to the present disclosure may include: a base layer unit having a side surface that is a plane; and a surface layer unit forming either a front side or a back side, with the base layer unit forming the other, and having a concave-convex shaped side surface on the same side as the side surface, the concave-convex shaped side surface having a concave portion and a convex portion whose shape is same as a shape plane-symmetrical to a shape of the concave portion with respect to a surface including the plane.

The above-mentioned inventions can be utilized in every combination possible.

Effects of the Invention

According to the method of laying the optical cable of the present disclosure, it is possible to lay and remove the optical cable in a stable place without civil engineering works. According to the laying strip of the present disclosure, it is possible to lay and remove the optical cable in a stable place without civil engineering works.

DESCRIPTION OF EMBODIMENTS

Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. The present disclosure is not limited to the following embodiments. The embodiments are merely examples, and the present disclosure can be implemented in various forms obtained by altering or modifying the embodiments based on the knowledge of those skilled in the art. Components denoted by the same reference numerals in the present specification and the drawings mutually denote the same components.

First Embodiment

An example of a method of laying an optical cable according to the present disclosure will be described with reference toFIGS.1to4. InFIGS.1to4, the reference numerals11and12denote laying strips, the reference numeral21denotes a road surface, and the reference numeral22denotes an optical cable.

FIG.1illustrates a laying strip11laid on a road surface21. The laying strip11is preferably composed of an elastic material such as rubber and resin so that it may smoothly adapt to unevenness of the road surface21and absorb vibration from the road surface21. When the laying strip11is long, roll thereof facilitates transportation to a laying site. When the laying strip11is divided into short and tile-like segments, the segments may be stacked for transportation. When the laying strip11is laid on the road surface21, fixing the laying strip11to the road surface21with an adhesive stabilizes the laying strip11. In the present embodiment, a surface having a smaller area of four longitudinal surfaces of each of the laying strip11and a laying strip12described later is referred to as a side surface. Alternatively, a surface to which an optical cable22is to be conformed is referred to as a side surface. In regard to surfaces having a larger area of respective four longitudinal surfaces of the laying strip11and the laying strip12described later, a surface that is to be in contact with the road surface21is referred to as a bottom surface, and a surface facing the bottom surface is referred to as a top surface.

FIG.2illustrates an optical cable22laid to conform to one side surface of a laying strip11. When the optical cable22cannot conform to the side surface of the laying strip11only by laying the optical cable22adjacent to the laying strip11, the optical cable22may be temporally tacked to the side surface of the laying strip11with an easily removable pin, a tape, an adhesive or the like to keep the optical cable22conforming to the side surface of the laying strip11.

FIG.3illustrates a laying strip12that is laid to conform to the laying strip11and the optical cable22that have been laid. The laying strip12is preferably composed of an elastic material such as rubber and/or resin so that it may smoothly adapt to unevenness of a road surface21and absorb vibration from the road surface21. When the laying strip12is long, roll thereof facilitates transportation to a laying site. When the laying strip12is divided into short and tile-like segments, the segments may be stacked for transportation. When the laying strip12is laid on the road surface21, fixing the laying strip12to the road surface21with an adhesive stabilizes the laying strip12.

The laying strip12has a side surface parallel to the side surface of the laying strip11to which the optical cable22conforms. The laying strip12is laid with the side surface of the laying strip11and the side surface of the laying strip12being parallel so that the optical cable22is sandwiched between the side surfaces.

FIG.4illustrates a situation in which the optical cable22is sandwiched between the side surface of the laying strip11and the side surface of the laying strip12. The laying strips11and12are preferably composed of an elastic material so that the potion for sandwiching is filled after the optical cable22is sandwiched therebetween.

When there are no obstacles in the place where the optical cable22is to be laid, the side surface of the laying strip11and the side surface of the laying strip12between which the optical cable22is to be sandwiched each may be a plane and the optical cable22may be sandwiched in a straight manner. On the other hand, when there are some obstacles that prevent the optical cable22from being laid in a straight manner, the side surface of the laying strip11and the side surface of the laying strip12between which the optical cable22is to be sandwiched each may be a curved surface bent in the longitudinal direction and the optical cable22may be sandwiched in a curved manner to avoid the obstacles. Not only for the laying on the road surface21, the same applies to the laying of the laying strip11and the laying strip12on a wall surface (not illustrated).

In the description forFIGS.1to4, the laying strip11is laid on the road surface21or the wall surface, the optical cable22is laid, the laying strip12is laid, and then the optical cable22is sandwiched. However, after the laying strips11and12are laid, the optical cable22may be laid. Alternatively, after the optical cable22is laid, the laying strips11and12may be laid simultaneously or one by one on the road surface21or the wall surface so that the optical cable22is sandwiched between the laying strips. Furthermore, the laying strips11and12and the optical cable22may be laid together on the road surface21or the wall surface after sandwiching the optical cable22between the laying strips11and12in advance.

Three or more laying strips may be laid. The additional laying of the third laying strip allows an optical cable to be additionally laid.

When the optical cable22is removed, the laying strips11and12may be torn off from the road surface21or the wall surface (not illustrated). The laying strips11and12may be torn off after the optical cable22is removed, or the laying strips11and12may be torn off with the optical cable22sandwiched therebetween.

According to the method of laying the optical cable of the present embodiment, it is possible to provide a method of laying an optical cable that is capable of laying and removing the optical cable in a stable place without civil engineering works.

Second Embodiment

An example of a method of laying an optical cable according to the present disclosure will be described with reference toFIGS.5to9. InFIGS.5to9, the reference numerals11and12each denote a laying strip, the reference numeral21denotes a road surface, the reference numeral22denotes an optical cable, the reference numeral31denotes a base layer unit, the reference numeral32denotes a surface layer unit, and the reference numeral33denotes a staple.

The laying strips11and12are typically fixed to the road surface21or the wall surface with an adhesive or the like so that their side surfaces are in contact with each other. However, in the scheme for sandwiching the optical cable22, the side surfaces could conceivably separate from each other, which results in exposing the sandwiched optical cable22. Therefore, for the laying strips11and12of the present embodiment, a preventive measure is taken to the laying strips11and12of the first embodiment to prevent a distance between the side surfaces of the laying strips11and12facing each other from being enlarged.

Hereinafter, two exemplary preventive measures are given, but the present invention is not limited to them. As a first example, taking the preventive measure may be, with the side surfaces of the laying strips11and12between which the optical cable22is sandwiched facing each other, engaging respective concave-convex shaped portions, apart from potions in contact with the optical cable22, included in the facing side surfaces of the laying strips11and12.

The first example will be described below.FIGS.5and6illustrate a laying strip11having a concave-convex shaped side surface. The laying strips11and12each are composed of a base layer unit31that is close to the bottom surface and a surface layer unit32that is close to the top surface, and the surface layer unit32forms either a front side or a back side, with the base layer unit31forming the other. The base layer unit31has a side surface that is a plane. In this example, this plane is referred to as a contact side surface. The surface layer unit32has a concave-convex shaped side surface on the same side as the contact side surface, and the concave-convex shaped side surface has a concave portion and a convex portion whose shape is same as a shape plane-symmetrical to a shape of the concave portion with respect to the surface including the contact side surface. In this example, the concave-convex shaped side surface of the surface layer unit32is referred to as a concave-convex side surface.

The base layer unit31of each of the laying strip11and the laying strip12has a thickness such that an optical cable22is entirely sandwiched between the contact side surface of the laying strip11and the contact side surface of the laying strip12. Furthermore, the laying strip11and the laying strip12desirably have the same thickness so that, with the laying strip11and the laying strip12laid, their surface layer units32are at the same height from a road surface21.

To allow the concave portion in the concave-convex side surface of the laying strip11and the convex portion in the concave-convex side surface of the laying strip12to be engaged with each other in laying the laying strip11and the laying strip12with their concave-convex side surfaces facing each other, the concave portion of the laying strip11and the convex portion of the laying strip12desirably have the same shape. In addition, to allow the convex portion in the concave-convex side surface of the laying strip11and the concave portion in the concave-convex side surface of the laying strip12to be engaged with each other, the convex portion of the laying strip11and the concave portion of the laying strip12desirably have the same shape.

To allow the concave-convex side surface of the laying strip11and the concave-convex side surface of the laying strip12to be engaged with each other in laying the laying strips with respective concave-convex side surfaces facing each other, the concave portions and convex portions are arranged so that the concave portion of the laying strip11is located in front of the convex portion of the laying strip12and the convex portion of the laying strip11is located in front of the concave portion of the laying strip12. For example, the laying strip11and the laying strip12are laid so that respective concave-convex side surfaces of the laying strip11and12are aligned at one longitudinal end and the concave-convex side surfaces face each other.

To allow the concave-convex side surface of the laying strip11and the concave-convex side surface of the laying strip12to be engaged with each other, the laying strip11and the laying strip12may have a concave-convex shape that starts with the concave portion at one end, ends with the convex potion at the other end, and has the concave and convex portions repeated between both ends. The convex portions and the concave portions included each in the laying strip11and the laying strip12may be formed to grow larger toward the ends to prevent the engaged portions from being separated on engaging the concave and convex portions with each other.

In this example, the optical cable22is sandwiched between the contact side surface of the laying strip11and the contact side surface of the laying strip12by the method of laying the optical cable of the first embodiment. According to the method of laying the optical cable of this example, the laying strip11is laid on the road surface21or a wall surface, the optical cable22is laid, the laying strip12is laid, the optical cable22is sandwiched, and then the concave-convex side surface of the laying strip11and the concave-convex side surface of the laying strip12may be engaged with each other. Alternatively, the laying strips11and12are laid, the optical cable22is laid, and then the concave-convex side surface of the laying strip11and the concave-convex side surface of the laying strip12may be engaged with each other. Furthermore, the optical cable22is laid, the laying strips11and12are laid on the road surface21or the wall surface one by one so that the optical cable22is sandwiched therebetween, and then the concave-convex side surface of the laying strip11and the concave-convex side surface of the laying strip12may be engaged with each other. When the optical cable22is laid and the laying strips11and12are simultaneously laid on the road surface21or the wall surface so that the optical cable22is sandwiched therebetween, the optical cable22is sandwiched and then the concave-convex side surface of the laying strip11and the concave-convex side surface of the laying strip12may be engaged with each other, or the concave-convex side surface of the laying strip11and the concave-convex side surface of the laying strip12are engaged with each other in advance and then the optical cable22may be sandwiched therebetween from the base layer unit31side. When the optical cable22is sandwiched between the laying strips11and12and they are laid together on the road surface21or the wall surface, the concave-convex side surface of the laying strip11and the concave-convex side surface of the laying strip12may be engaged with each other before or after they are laid.

As illustrated inFIGS.7and8, engaging the concave-convex side surface of the laying strip11and the concave-convex side surface of the laying strip12with each other can prevent a distance between the contact side surface of the laying strip11and the contact side surface of the laying strip12from being enlarged.

As a second example, taking the preventive measure may be, with the side surfaces of the laying strips11and12between which the optical cable22is sandwiched facing each other, thrusting the tips of staples across the facing side surfaces of the laying strips11and12.FIG.9illustrates a method of laying the optical cable in which the staples33are thrust in the top surfaces of the laying strip11and the laying strip12having the optical cable22sandwiched therebetween.

In this example, the optical cable22is sandwiched between the side surfaces of the laying strip11and laying strip12facing each other by the method of laying the optical cable of the first embodiment. According to the method of laying the optical cable of this example, the laying strip11is laid on the road surface21or the wall surface, the optical cable22is laid, the laying strip12is laid, the optical cable22is sandwiched, and then the staples33may be thrust in the top surfaces of the laying strip11and the laying strip12across the side surfaces facing each other. Alternatively, the laying strips11and12are laid, the optical cable22is laid, and then the staples33may be thrust in the top surfaces of the laying strip11and the laying strip12across the side surfaces facing each other. Furthermore, the optical cable22is laid, the laying strips11and12are laid on the road surface21or the wall surface one by one so that the optical cable22is sandwiched therebetween, and then the staples33may be thrust in the top surfaces of the laying strip11and the laying strip12across the side surfaces facing each other. When the optical cable22is laid and the laying strips11and12are simultaneously laid on the road surface21or the wall surface so that the optical cable22is sandwiched therebetween, the optical cable22is sandwiched and then the staples33may be thrust in the top surfaces of the laying strip11and the laying strip12across the side surfaces facing each other, or the staples33are thrust in the top surfaces of the laying strip11and the laying strip12across the side surfaces facing each other in advance and then the optical cable22may be sandwiched from the surfaces opposite to the surfaces having the staples33thrust therein. When the optical cable22is sandwiched between the laying strips11and12and they are laid together on the road surface21or the wall surface, the staples33may be thrust in the top surfaces of the laying strip11and the laying strip12across the side surfaces facing each other before or after they are laid.

Thrusting staples33in the laying strips11and12can prevent a distance between the side surface of the laying strip11and the side surface of the laying strip12facing each other from being enlarged. Using a tape or the like instead of the staple33can provide the similar effect.

According to the method of laying the optical cable of the present embodiment, it is possible to provide a method of laying an optical cable that is capable of laying and removing the optical cable in a stable place without civil engineering works.

Furthermore, taking the preventive measure to prevent a distance between the side surfaces of the laying strips11and12facing each other from being enlarged can prevent the optical cable22sandwiched between the laying strips11and12from being exposed.

According to the laying strip of the present embodiment, it is possible to provide a method of laying an optical cable that is capable of laying and removing the optical cable in a stable place without civil engineering works.

Furthermore, taking the preventive measure to prevent a distance between the side surfaces of the laying strips11and12facing each other from being enlarged can prevent the optical cable22sandwiched between the laying strips11and12from being exposed.

Third Embodiment

An example of a method of laying an optical cable according to the present disclosure will be described with reference toFIGS.10to14. InFIGS.10to14, the reference numerals11and12each denote a laying strip, the reference numeral13denotes a space, the reference numeral14denotes a tray, the reference numeral15denotes a lid, the reference numeral16denotes a cut, the reference numeral21denotes a road surface, the reference numeral22denotes an optical cable, the reference numeral23denotes an optical fiber core wire, and the reference numeral24denotes a connection unit.

FIG.10illustrates a laying strip11laid on a road surface21. The configuration and the laying process of the laying strip11and a laying strip12described later are the same as those in the first embodiment or the second embodiment.

FIGS.11and12illustrate the laying strip11in a process to form a space for accommodating a connection unit of an optical cable. As illustrated inFIG.11, a cut16is made to cut out a part of the laying strip11, and as illustrated inFIG.12, the part is then cut out along the cut16to form the space13for accommodating the connection unit of the optical cable. The space13positioned to include a part of the side surface of the laying strip11allows the optical cable22and the space13for accommodating the connection unit to be located adjacent to each other with the optical cable22sandwiched between the side surface of the laying strip11and a side surface of another laying strip, which facilitates accommodating the connection unit of the optical cable. The space13formed in the center of the laying strip11causes the optical cable22and the space13for accommodating the connection unit to be spaced apart when the optical cable22is sandwiched between the laying strip11and another laying strip, which creates a need to form a path of the optical cable22to the space13. For example, a cut line needs to be formed. When the space13is formed after the laying strip11is laid on the road surface21or a wall surface (not illustrated), the space13having a desired shape can be formed in a desired position depending on the environment in which the laying strip11is to be laid.

In the description forFIGS.10to12, the space13is formed after the laying strip11is laid on the road surface21or the wall surface, but the laying strip11in which the space13is formed in advance may be laid on the road surface21or the wall surface. Forming the space13in advance at a site where a tool and an environment are prepared can facilitate forming the space13.

Alternatively, the laying strip11may have a perforated line in advance to form the space13for accommodating the connection unit of the optical cable. In laying the laying strip11, cutting the laying strip11using the perforated line to form the space13facilitates forming the space13in which the connection unit is to be installed.

A new space13may be additionally formed in the laying strip11having the space13formed therein. The additional formation of the new space13allows an optical cable to be additionally laid and a connection unit to be additionally accommodated.

FIGS.13to14illustrate a situation in which a connection unit is accommodated in the laying strip11. As illustrated inFIG.13, a tray14, in which the connection unit is to be arranged, is provided at the bottom of the formed space13. The tray14is desirably sized and shaped to be contained in the space13. Before or after the tray14is installed, the optical cable22is sandwiched between the laying strip11and the laying strip12.

As illustrated inFIG.13, when the optical cable22is connected or branched, optical fiber core wires23are exposed at the end of the optical cable22and connected to form the connection unit24. The extra-length portions of the optical fiber core wires23and the connection unit24are accommodated in the tray14. With the tray14being provided, the extra-length portions of the optical fiber core wires23and the connection unit24can be protected. This eliminates the need to separately install a closure or ground box for accommodating the connection unit24.

The space13may be formed after the optical cable22is sandwiched. When the laying strip11and the laying strip12are the same as those of the second embodiment, the space13may be formed after the preventive measure is taken. In this procedure, the connection unit24can be arranged in an appropriate position to adapt to the actual length of the optical cable22, which eliminates the need to adjust the length of the optical cable22. Accordingly, the waste of cutting the extra-length portion of the optical cable22is eliminated, and the trouble is also eliminated in which the optical cable22having an insufficient length is replaced with the optical cable22having a sufficient length.

As illustrated inFIG.14, the open side of the space13is covered with a lid15. Being covered with the lid15, the connection unit24and the optical fiber core wire23can be protected. The material of the lid15is preferably similar to that of the laying strip11. The shape of the lid15preferably fit to the open side of the space13.

When the optical cable22is removed, the laying strip11and the laying strip12may be torn off from the road surface21or the wall surface (not illustrated). The laying strip11and the laying strip12may be torn off after the optical cable22is removed, or the laying strip11and the laying strip12may be torn off with the optical cable22sandwiched therebetween.

When the laying strip is laid on the road surface according to the above embodiment, components to be used such as a laying strip, an optical cable, and a tray, which are constituted of articles such that the laying strip is kept, for example, within about 1 cm in width and which have appropriate mechanical properties, can provide a design that does not cause failure due to being trampled or the like. As a result, wiring can be economically built which does not get in the way on the road surface and does not obstruct passage similarly to underground wiring or overhead wiring.

According to the method of laying the optical cable of the present embodiment, a method of laying an optical cable can be provided which is capable of laying and removing the optical cable in a stable place without civil engineering works.

INDUSTRIAL APPLICABILITY

The method of laying the optical cable according to the present disclosure can be applied to the information and communication industry.

REFERENCE SIGNS LIST