JP7156178B2 - fiber optic cable - Google Patents

Description

TECHNICAL FIELD The present disclosure relates to optical fiber cables with multiple optical fiber cores.

Patent Literature 1 describes an optical fiber cable having intermittently connected optical fiber tape core wires in a pipe.
Patent document 2 discloses an optical fiber in which a unit is mounted by winding an identification thread around the outer circumference of an optical fiber bundle in which a plurality of single coated optical fibers constituting an intermittently connected optical fiber ribbon are assembled. Cables are listed.
Patent Document 3 describes a slot rod type optical fiber cable.

Japanese Patent Application Publication No. 2015-517679 JP-A-2010-8923 JP 2014-71441 A

In the case of a structure having tensile strength members on both sides of the jacket, the optical fiber cable tends to bend in a 90-degree direction with respect to a line connecting the tensile members in a cross-sectional view, and tends to have low bending rigidity in that direction. On the other hand, the tensile strength member tends to be difficult to bend in a certain direction and have a large bending rigidity in that direction. That is, the optical fiber cable having the above structure has bending anisotropy.
If the optical fiber cable for pneumatic feeding has the above structure, it has bending anisotropy, so when pneumatic feeding or pushing into the duct, it is easy to bend in the direction of low bending rigidity, and there is a risk of buckling in the middle of the duct. be.
In addition, optical fiber cables for pneumatic transmission are desired to have a smaller diameter and lighter weight for high-density mounting of optical fibers. ing. Further, in order to further increase the density, there are cases where the jacket thickness is reduced or a hard jacket is used. For this reason, only a thin tensile strength member can be put in the jacket, which causes problems such as a reduction in the rigidity of the optical fiber cable and difficulty in suppressing the linear expansion of the jacket.

An object of the present disclosure is to provide an optical fiber cable for pneumatic feeding that has bending rigidity suitable for pneumatic feeding.

An optical fiber cable according to an aspect of the present disclosure includes a connection part in which adjacent optical fiber core wires are connected, and the adjacent optical fiber core wires are connected in part or all of the optical fiber core wires. an intermittently connected optical fiber ribbon in which non-connected portions are intermittently provided in the longitudinal direction;
a cable jacket enclosing a plurality of the optical fiber tape core wires;
two or more tensile strength members provided to be embedded inside the cable jacket;
An optical fiber cable having
The radial bending rigidity of the optical fiber cable is 0.3 N·m ² or more and 1.5 N·m ² or less in the circumferential direction,
The core density obtained by dividing the number of cores of the optical fiber core wire by the cross-sectional area of the cable is 5.0 cores/mm ² or more ,
A ratio of the total cross-sectional area of the plurality of tensile members to the cross-sectional area of the cable jacket is 2.4% or more.

According to the present disclosure, it is possible to provide an optical fiber cable for pneumatic feeding that has bending rigidity suitable for pneumatic feeding.

It is a sectional view showing composition of an optical fiber cable concerning a first embodiment. FIG. 2 is a plan view showing an example of an optical fiber tape core wire accommodated in an optical fiber cable; FIG. 4 is a cross-sectional view showing the configuration of an optical fiber cable according to a second embodiment; FIG. 10 is a cross-sectional view showing the configuration of an optical fiber cable according to a third embodiment; FIG. 11 is a cross-sectional view showing the configuration of an optical fiber cable according to a fourth embodiment; It is a schematic diagram which shows a cable pumping evaluation apparatus.

(Description of Embodiments of the Present Disclosure)
First, the embodiments of the present disclosure are listed and described.
A fiber optic cable according to one aspect of the present disclosure includes:
(1) Between some or all of the optical fiber core wires, a connecting portion where the adjacent optical fiber core wires are connected and a non-connecting portion where the adjacent optical fiber core wires are not connected are arranged in the longitudinal direction. Intermittently connected optical fiber ribbons provided intermittently,
a cable jacket enclosing a plurality of the optical fiber tape core wires;
two or more tensile strength members provided to be embedded inside the cable jacket;
An optical fiber cable having
The radial bending rigidity of the optical fiber cable is 0.3 N·m ² or more and 1.5 N·m ² or less in the circumferential direction,
The core density obtained by dividing the number of cores of the optical fiber core wire by the cross-sectional area of the cable is 5.0 cores/mm ² or more ,
A ratio of the total cross-sectional area of the plurality of tensile members to the cross-sectional area of the cable jacket is 2.4% or more.
According to the optical fiber cable having the above structure, by using the intermittently connected optical fiber ribbon, an optical fiber cable for pneumatic feeding with a core density of 5.0 cores/mm ² or more can be realized. The optical fiber cable configured as described above can obtain an appropriate bending rigidity suitable for pneumatic feeding by being within the above bending rigidity range. In addition, since the radial bending rigidity is 0.3 N·m ² or more in the circumferential direction, buckling during pneumatic feeding of the optical fiber cable can be suppressed. Since it is 1.5 N·m ² or less, it is easy to store the excess length of the optical fiber cable.

(2) the number of the tensile strength members is four;
Two pairs of the tensile strength members are provided at positions facing each other across the center of the optical fiber cable in a cross-sectional view,
The positions of the four tensile strength members in a cross-sectional view may be positions where two straight lines connecting two of the tensile strength members forming a pair intersect each other at right angles.
According to the optical fiber cable having the above configuration, the four tensile members are present in a well-balanced manner inside the cable sheath, so that the bending anisotropy of the optical fiber cable (biased direction in which it is easy to bend) can be suppressed. As a result, the optical fiber cable can be properly pneumatically fed.

(3) The tensile strength member may be a plate-like member having an arc-shaped cross section along the curved surface of the cable jacket.
According to the optical fiber cable having the above configuration, since the tensile strength member is embedded in the cable jacket over a large angle when viewed from the center of the cable jacket, bending anisotropy of the optical fiber cable can be suppressed. . As a result, the optical fiber cable can be properly pneumatically fed.

According to the optical fiber cable configured as described above, the ratio of the cross-sectional area of the tensile strength member to the cross-sectional area of the member forming the cable jacket is increased, so that the rigidity of the optical fiber cable can be increased.

( 4 ) The tensile strength member may be fiber reinforced plastic.
According to the optical fiber cable having the above configuration, since the tensile member is made of fiber reinforced plastics (FRP), it is possible to reduce the weight while ensuring the rigidity of the optical fiber cable.

( 5 ) The fiber-reinforced plastic may be aramid FRP.
According to the optical fiber cable having the above structure, since the aramid FRP has a smaller coefficient of linear expansion than the cable jacket, it is possible to suppress contraction of the cable jacket at low temperatures.

( 6 ) The cable jacket may contain a silicone-based lubricant.
According to the optical fiber cable having the above configuration, the coefficient of friction of the cable jacket can be lowered, so when the optical fiber cable is pneumatically fed through the duct, the friction between the cable jacket and the duct is reduced, and the pumping distance can be extended. can be done.

( 7 ) The cable sheath may have projections on the outer periphery.
According to the optical fiber cable having the above configuration, the contact area between the cable jacket and the duct can be reduced when the optical fiber cable is pneumatically fed through the duct. This reduces the friction between the cable jacket and the duct, allowing longer pumping distances.

( 8 ) the protrusion has a curved surface at the end in the direction in which the protrusion protrudes;
A curvature radius of the curved surface may be 2.5 mm or more.
According to the optical fiber cable having the above configuration, the end portion in the projecting direction of the projection is formed with a curved surface, and the radius of curvature is 2.5 mm or more, so the end portion has a gentle shape. As a result, when the optical fiber cable is inserted into a wiring member such as a closure, it is possible to prevent airtightness from deteriorating due to unevenness caused by the protrusion. Therefore, the ingress of water into the closure can be suppressed.

( 9 ) The protrusion is a plate-shaped protrusion in a cross-sectional view that protrudes in the radial direction of the optical fiber cable,
The protrusions are arranged spirally continuously along the longitudinal direction of the optical fiber cable.
According to the optical fiber cable having the above configuration, the plate-like projecting body in a cross-sectional view projecting in the radial direction of the optical fiber cable is continuously arranged spirally along the longitudinal direction of the optical fiber cable. , the inner surface of the projection is likely to be subjected to wind pressure along the longitudinal direction. Therefore, when the wind is blown along the longitudinal direction of the optical fiber cable, the projecting body receives wind pressure, so that when the optical fiber cable is pneumatically fed in the duct, the pumping distance can be extended.

( 10 ) The optical fiber core wire has a glass fiber and a coating that covers the outer circumference of the glass fiber,
The coating comprises two coating layers,
The outer coating layer of the two coating layers,
a base resin containing a urethane acrylate oligomer or urethane methacrylate oligomer, a monomer having a phenoxy group, a photopolymerization initiator and a silane coupling agent;
A cured product of a resin composition containing hydrophobic inorganic oxide particles,
A content of the inorganic oxide particles in the resin composition may be 1% by mass or more and 45% by mass or less based on the total amount of the resin composition.
According to the optical fiber cable having the above configuration, the side pressure resistance of the optical fiber core wire is enhanced by using the cured resin composition as the outer coating layer constituting the coating of the optical fiber core wire. As a result, an increase in transmission loss of the optical fiber cable can be suppressed.

( 11 ) The optical fiber has a bending loss at a wavelength of 1550 nm of 0.5 dB or less with a bending diameter of φ15 mm×1 turn and 0.1 dB or lower with a bending diameter of φ20 mm×1 turn.
According to the optical fiber cable having the above configuration, by using the optical fiber core wire as described above, the lateral pressure characteristics can be improved, and the low temperature loss characteristics can be improved.

(Details of embodiments of the present disclosure)
A specific example of an optical fiber cable according to an embodiment of the present disclosure will be described below with reference to the drawings.
The present invention is not limited to these exemplifications, but is indicated by the scope of the claims, and is intended to include all modifications within the scope and meaning equivalent to the scope of the claims.

(First embodiment)
An optical fiber cable 1A according to the first embodiment will be described with reference to FIGS. 1 and 2. FIG.
FIG. 1 is a cross-sectional view perpendicular to the length direction of the optical fiber cable 1A. As shown in FIG. 1, an optical fiber cable 1A includes a plurality of optical fiber ribbons 2, a water absorbing tape 3 surrounding the optical fiber ribbons 2, and a cable jacket 4 surrounding the water absorbing tape 3. , a tensile member 5 A ( 5 ) provided inside the cable jacket 4 and a tear string 6 .

The water absorbing tape 3 is wound around the entirety of the plurality of optical fiber ribbons 2, for example, vertically or horizontally. The water-absorbing tape 3 is, for example, a base fabric made of polyester or the like which has undergone water-absorbing processing by adhering water-absorbing powder thereto.

The cable jacket 4 is made of resin such as polyethylene (PE), for example. The resin of the cable jacket 4 preferably has a Young's modulus of 500 Pa or more. Moreover, it is preferable that the cable jacket 4 contains a silicon-based lubricant. The silicon-based lubricant is preferably contained, for example, at a rate of 2 wt % or more. The cable jacket 4 is made of thermoplastic resin, for example, and is formed by extruding the resin onto the plurality of optical fiber tape core wires 2 around which the water absorbing tape 3 is wound.

The tensile strength member 5A is provided so as to be embedded inside the cable sheath 4. As shown in FIG. The tensile member 5A is made of fiber reinforced plastic (FRP). The tensile member 5A is, for example, aramid FRP, glass FRP, carbon FRP, or the like, but it is preferable to use aramid FRP, which has excellent flexibility. Since the aramid FRP has a smaller coefficient of linear expansion than the cable jacket 4, shrinkage of the cable jacket 4 at low temperatures can be suppressed. 5 A of tensile strength bodies are formed in circular cross-sectional view. A plurality of (in this example, four) tensile members 5A are provided.
Each of the four strength members 5A is provided with two pairs of two strength members 5A that are opposed to each other across the center of the optical fiber cable in a cross-sectional view. The positions of the four tensile strength members 5A in a cross-sectional view are positions at which the two straight lines connecting the two paired tensile members 5A intersect each other. Each tensile member 5A is provided inside the cable jacket 4 along the longitudinal direction of the optical fiber cable 1A.

The tear string 6 is for tearing the cable jacket 4, and is embedded in the cable jacket 4 along the longitudinal direction of the optical fiber cable 1A. In the case of this example, two tearing strings 6 are provided. The two tearing strings 6 are provided substantially in the middle of the adjacent tensile strength members 5A so as to face each other. By pulling out the tear string 6, the cable jacket 4 is torn in the longitudinal direction, and the optical fiber ribbon 2 can be taken out. The tear string 6 is made of, for example, a plastic material (eg, polyester) that is resistant to tension.

In the optical fiber cable 1A having such a configuration, the ratio of the total cross-sectional area of the four tensile members 5A to the cross-sectional area of the members forming the cable jacket 4 is 2.4% or more. For example, when four aramid FRPs with an outer diameter of 0.5 mm are placed in a jacket with an outer diameter of 10 mm and a jacket thickness of 1.2 mm, the four tensile strength members 5A with respect to the cross-sectional area of the member forming the cable jacket 4 The percentage of total cross-sectional area is 2.42%. With the above structure, the loss temperature characteristic at -30 to +70 ° C. is 0.1 dB / km or less, so the ratio of the total cross-sectional area of the four tensile strength members 5A to the cross-sectional area of the members forming the cable jacket 4 is preferably 2.4% or more.

FIG. 2 shows an example of the optical fiber ribbon 2 accommodated in the optical fiber cable 1A. As shown in FIG. 2, the optical fiber tape core wire 2 includes a connecting portion 12 in which a plurality of optical fiber core wires 11A to 11L are arranged in parallel and the adjacent optical fiber core wires are connected to each other. It is an intermittently connected optical fiber tape core wire in which non-connected portions 13 where the optical fiber core wires are not connected are intermittently provided in the longitudinal direction.

The optical fiber ribbon 2 of this example has 12 optical fibers 11A to 11L arranged in parallel. FIG. 2 shows a plan view of the optical fiber ribbon 2 with the optical fibers 11A to 11L opened in the arrangement direction, and a cross-sectional view of the optical fiber 11A. The locations where the connecting portions 12 and the non-connecting portions 13 are intermittently provided may be between part of the optical fiber core wires as shown in FIG. 2, or between all the optical fiber core wires. There may be. In the example shown in FIG. 2, no non-connecting portion 13 is provided between the optical fibers 11A and 11B, 11C and 11D, 11E and 11F, 11G and 11H, 11I and 11J, and 11K and 11L.

The connecting portion 12 in the optical fiber tape core wire 2 is formed by applying a connecting resin 14 made of, for example, an ultraviolet curable resin, a thermosetting resin, or the like between the optical fiber core wires. By applying the connecting resin 14 between the predetermined optical fiber core wires, the connecting portion 12 and the non-connecting portion 13 are provided intermittently, and the respective optical fiber core wires 11A to 11L are integrated in a parallel state. be. The coupling resin 14 may be applied to only one surface of the parallel surfaces formed by the optical fibers 11A to 11L arranged in parallel, or may be applied to both surfaces. Further, the optical fiber tape core wire 2 is formed by, for example, applying a tape resin to one side or both sides of the optical fiber core wires 11A to 11L arranged in parallel to connect all the optical fiber core wires 11A to 11L. Alternatively, the non-connecting portion 13 may be formed by cutting a portion thereof with a rotary blade or the like.

The optical fiber core wires 11A to 11L have, for example, a glass fiber 15 composed of a core and a clad, and two coating layers 16 and 17 that coat the outer periphery of the glass fiber 15. As shown in FIG. The inner coating layer 16 of the two coating layers is made of a hardened primary resin. The outer coating layer 17 of the two coating layers is made of a hardened secondary resin. The optical fiber core wires 11A to 11L are so-called thin core wires, and their outer diameter A is 165 μm or more and 220 μm or less.

A soft resin having a relatively low Young's modulus is used as a buffer layer for the primary resin that constitutes the inner coating layer 16 that contacts the glass fiber 15 . A hard resin having a relatively high Young's modulus is used as a protective layer for the secondary resin forming the outer coating layer 17 . The cured product of the secondary resin has, for example, a Young's modulus at 23° C. of 900 MPa or more, preferably 1000 MPa or more, more preferably 1500 MPa or more.

The secondary resin that constitutes the coating layer 17 includes a base resin containing a urethane acrylate oligomer or a urethane methacrylate oligomer, a monomer having a phenoxy group, a photopolymerization initiator and a silane coupling agent, and a hydrophobic inorganic oxide. It is preferably a resin composition containing particles. The content of the inorganic oxide particles in the resin composition is 1% by mass or more and 45% by mass or less based on the total amount of the resin composition.

Hereinafter, acrylates or their corresponding methacrylates are referred to as (meth)acrylates.

As the urethane (meth)acrylate oligomer, an oligomer obtained by reacting a polyol compound, a polyisocyanate compound and a hydroxyl group-containing (meth)acrylate compound can be used. This oligomer can be obtained, for example, by reacting polypropylene glycol having a molecular weight of 4000, isophorone diisocyanate, hydroxyethyl acrylate and methanol.

A (meth)acrylate compound having a phenoxy group can be used as the monomer having a phenoxy group. For example, the monomer having a phenoxy group is nonylphenol EO-modified acrylate (trade name “Aronix M-113” manufactured by Toagosei Co., Ltd.).

The photopolymerization initiator can be appropriately selected from known radical photopolymerization initiators and used, for example, the photopolymerization initiator is 2,4,6-trimethylbenzoyldiphenylphosphine oxide.

The silane coupling agent is not particularly limited as long as it does not interfere with curing of the resin composition. For example, silane coupling agents include 3-mercaptopropyltrimethoxysilane.

Hydrophobic inorganic oxide particles have a hydrophobic group introduced to the surface of the inorganic oxide particles. Inorganic oxide particles are, for example, silica particles. Hydrophobic groups are reactive groups such as (meth)acryloyl groups and vinyl groups, or non-reactive groups such as hydrocarbon groups (e.g., alkyl groups) and aryl groups (e.g., phenyl groups). good.

By adding the inorganic oxide particles to the secondary resin that forms the coating layer 17, the lateral pressure characteristics of the optical fiber core wires 11A to 11L are improved. The primary resin and the secondary resin that constitute the coating layer 16 are made of, for example, an ultraviolet curable resin, a thermosetting resin, or the like. In addition, the optical fibers 11A to 11L have a bending loss of 0.5 dB or less at a wavelength of 1550 nm with a bending diameter of φ15 mm×1 turn, and a bending loss of 0.1 dB or lower with a bending diameter of φ20 mm×1 turn. A bending loss equivalent to 657A2 is preferable. By using such an optical fiber core wire, the lateral pressure characteristics can be improved, and the low-temperature loss characteristics can be improved.

The optical fiber tape core wires 2 are rolled and collected when they are accommodated in the optical fiber cable 1A. Alternatively, a plurality of optical fiber tape core wires 2 may be twisted together to form a unit, and the plurality of units may be assembled. The bundled optical fiber ribbons 2 may be bundled with a bundle material or the like, or may be bundled with a bundle material for each unit.

In the optical fiber cable 1A configured as described above, the bending rigidity in the radial direction of the optical fiber cable 1A is 0.3 N·m ² or more and 1.5 N·m ² or less in the entire circumferential direction. Further, the core density obtained by dividing the number of cores of all the optical fibers constituting the plurality of optical fiber tape core wires 2 by the cable cross-sectional area of the optical fiber cable 1A is 5.0 cores/mm ² or more. Moreover, since the diameter of a general microduct is 14 mm or less, it is desirable that the outer diameter of the optical fiber cable 1A is 11 mm or less. Considering air feeding, the unit weight of the optical fiber cable 1A is desirably 200 kg/km or less.

For example, the outer diameter of the optical fiber cable 1A is 10 mm, the thickness of the cable jacket 4 is 1.0 mm, and the outer diameter A of the optical fiber core wire is 200 μm. If the total number of 12 optical fiber ribbons 2 is 36, then the total number of optical fiber ribbons is 432 and the core density is 5.5 fibers/mm ² . In this example, the optical fiber ribbon 2 with 12 cores is used, but an optical fiber ribbon with 16 cores or 24 cores, for example, may be used.

The optical fiber cable 1A according to the first embodiment includes a plurality of optical fiber tape core wires 2, a cable jacket 4 that covers the periphery of these optical fiber tape core wires 2, and a cable jacket 4 embedded inside the cable jacket 4. It has four tensile members 5A. The radial bending rigidity of the optical fiber cable 1A is configured to be 0.3 N·m ² or more and 1.5 N·m ² or less in the entire circumferential direction. Further, the core density obtained by dividing the total number of cores of the optical fibers 11A to 11L forming the optical fiber tape core 2 by the cross-sectional area of the cable is 5.0 cores/mm ² or more.

By using the intermittently connected optical fiber tape core wires 2, each optical fiber tape core wire 2 and a plurality of optical fiber tape core wires 2 can be more effectively compared with non-intermittently connected optical fiber tape core wires. Dense aggregates are possible. Therefore, as an optical fiber cable for pneumatic feeding, an optical fiber cable having a core density of 5.0 cores/mm ² or more can be realized. In addition, since the outer diameter of the assembly of the optical fiber tape core wires 2 can be reduced, the cable sheath 4 can be formed thicker while ensuring a core density of 5.0 cores/mm ² or more. It is possible to embed a relatively thick tensile member 5A in the cover 4. Thereby, the rigidity of the optical fiber cable 1A can be increased. In addition, by setting the radial bending stiffness of the optical fiber cable 1A in the range of 0.3 N·m ² or more and 1.5 N·m ² or less in the entire circumferential direction, light having an appropriate bending stiffness suitable for pneumatic feeding can be obtained. It can be a fiber cable. For example, since the bending rigidity is 0.3 N·m ² or more, it is possible to suppress the occurrence of buckling when the optical fiber cable 1A is pneumatically fed. In addition, since the bending rigidity is 1.5 N·m ² or less, the optical fiber cable 1A can be bundled into an appropriate size when storing the extra length of the optical fiber cable 1A in a hand hole or the like. and good storability.

Further, the optical fiber cable 1A is provided with two pairs of two tensile strength members 5A that form a pair inside the cable sheath 4 and are opposed to each other across the center of the optical fiber cable 1A in a cross-sectional view. That is, the optical fiber cable 1A is provided with four tensile members 5A inside the cable sheath 4. As shown in FIG. The positions of the four tensile strength members 5A in a cross-sectional view are positions at which the two straight lines connecting the two paired tensile members 5A intersect each other. Therefore, since the four tensile members 5A are present in the cable jacket 4 in a well-balanced manner, it is possible to suppress the bending anisotropy of the optical fiber cable 1A. Therefore, according to such a configuration, it is possible to provide an optical fiber cable having bending rigidity suitable for pneumatic feeding.

Also, the optical fiber cable 1A is constructed so that the ratio of the cross-sectional area of the tensile member 5A to the cross-sectional area of the member forming the cable jacket 4 is 2.4% or more. Furthermore, the tensile strength member 5A is made of fiber reinforced plastic. Therefore, the ratio of the tensile member 5A is increased, so that the rigidity of the optical fiber cable 1A can be appropriately increased, and the optical fiber cable 1A can be made suitable for pneumatic feeding. In addition, by using fiber-reinforced plastic, the optical fiber cable 1A can be lightened while ensuring its rigidity. In addition, since the proportion of the tensile strength member 5A is increased, by using a fiber-reinforced plastic having a linear expansion coefficient smaller than that of the cable jacket 4, shrinkage of the cable jacket 4 at low temperatures is effectively suppressed. be able to.

In the optical fiber cable 1A, the resin of the cable jacket 4 contains a silicone-based lubricant. Therefore, since the coefficient of friction of the cable jacket 4 can be lowered, when the optical fiber cable 1A is pneumatically fed through the duct, the friction between the cable jacket 4 and the duct is reduced, the wire routing is improved, and the pumping distance is extended. be able to. In addition, since the resin of the cable jacket 4 has a Young's modulus of 500 Pa or more, it is possible to increase the lateral pressure resistance when the optical fiber cable 1A is bent, for example.

Further, according to the optical fiber cable 1A, by using the cured product of the resin composition as the outer coating layer 17 constituting the coating of the optical fiber core wires 11A to 11L, the optical fiber core wires 11A to 11L can be Side pressure resistance can be strengthened. Therefore, if the optical fiber tape core wire 2 is configured using such optical fiber core wires 11A to 11L, it is possible to suppress an increase in transmission loss when accommodated in the optical fiber cable 1A.
Also, the optical fibers 11A to 11L are specified by ITU-T G.3. The bending loss equivalent to 657A2 also improves the lateral pressure characteristics, and the low temperature loss characteristics can also be improved.

(Second embodiment)
An optical fiber cable 1B according to the second embodiment will be described with reference to FIG. In addition, the same code|symbol is attached|subjected about the structure similar to 1 A of optical fiber cables which concern on said 1st embodiment, and the description is abbreviate|omitted.

FIG. 3 is a cross-sectional view perpendicular to the length direction of the optical fiber cable 1B. As shown in FIG. 3, the optical fiber cable 1B includes a plurality of intermittently connected optical fiber ribbons 2, a water absorbing tape 3 surrounding the optical fiber ribbons 2, and a cable surrounding the water absorbing tape 3. It comprises a jacket 4, a tensile strength member 5B (5) provided inside the cable jacket 4, and a tear string 6. The tensile strength member 5B is a plate-like tensile member whose cross section is formed in an arc shape along the curved surface of the cable jacket 4. As shown in FIG.

A plurality of (two in this example) tensile members 5B are provided. The two tensile members 5B are provided inside the cable jacket 4 and arranged to face each other. The tensile strength member 5B is provided, for example, in an arc shape with a central angle θ in the range of 30 degrees to 90 degrees in the optical fiber cable 1B. The total cross-sectional area of the two tensile members 5B is 2.4% or more of the cross-sectional area of the members forming the cable jacket 4. A thickness B in the radial direction of the tensile member 5B is adjusted according to the length of the arc of the tensile member 5B along the curved surface of the cable jacket 4 . The tensile member 5B is a plate-shaped member made of fiber-reinforced plastic such as aramid or glass, and is provided along the longitudinal direction of the optical fiber cable 1B, similar to the tensile member 5A of the first embodiment. there is Other configurations are the same as those of the optical fiber cable 1A.

According to the optical fiber cable 1B according to the second embodiment, when viewed from the center of the optical fiber cable 1B, the two sheets extend over a large angle (for example, the central angle θ = 30 degrees to 90 degrees) in the cable jacket 4. A tensile strength member 5B is embedded. For this reason, the optical fiber cable 1B can further suppress bending anisotropy compared to an optical fiber cable having a tensile strength member having a circular cross-sectional view on both sides of the jacket. Moreover, the rigidity of the optical fiber cable 1B can be increased appropriately. As a result, the optical fiber cable can be made suitable for pneumatic feeding.

(Third embodiment)
An optical fiber cable 1C according to the third embodiment will be described with reference to FIG. In addition, the same code|symbol is attached|subjected about the structure similar to 1 A of optical fiber cables which concern on said 1st embodiment, and the description is abbreviate|omitted.

FIG. 4 is a cross-sectional view perpendicular to the length direction of the optical fiber cable 1C. As shown in FIG. 4, the optical fiber cable 1C includes a plurality of intermittently connected optical fiber ribbons 2, a water absorbing tape 3 surrounding the optical fiber ribbons 2, and a cable surrounding the water absorbing tape 3. It comprises a jacket 4 and a tensile member 5 and a tear string 6 provided inside the cable jacket 4 .
In addition, although the tensile strength member 5 is illustrated as being the same as the four tensile strength members 5A having a circular cross-sectional view in the optical fiber cable 1A according to the first embodiment, It may be the same as the two plate-like tensile members 5B in cross section in the optical fiber cable 1B.
Furthermore, the optical fiber cable 1C has projections 8 on the outer periphery of the cable sheath 4. As shown in FIG.

A plurality of protrusions 8 (eight in this example) are provided. Eight protrusions 8 are provided along the longitudinal direction of the optical fiber cable 1C. Each protrusion 8 may be provided continuously along the longitudinal direction, or may be provided intermittently. Further, the eight protrusions 8 are provided on the outer peripheral portion of the cable jacket 4 at approximately equal intervals in a cross-sectional view. The protrusion 8 has a curved surface at an end portion 8a in the direction in which the protrusion 8 protrudes, and the radius of curvature of the curved surface is formed to be 2.5 mm or more. The protrusions 8 are integrally formed with the cable jacket 4 by extrusion. Other configurations are the same as those of the optical fiber cable 1A.

According to the optical fiber cable 1C according to the third embodiment, a plurality of protrusions 8 are provided on the outer peripheral portion of the cable jacket 4 along the longitudinal direction of the optical fiber cable 1C. Therefore, when the optical fiber cable 1C is pneumatically fed through the duct, the projection 8 comes into contact with the inner wall of the duct, so the contact area between the cable jacket 4 and the duct can be reduced. As a result, the friction between the cable jacket 4 and the duct is reduced, and the pumping distance can be extended.

Further, according to the optical fiber cable 1C, the projection 8 has a curved surface at the end 8a in the projecting direction, and is formed so as to have a gentle shape with a radius of curvature of 2.5 mm or more. . As a result, for example, when the optical fiber cable 1C is inserted into a wiring member such as a closure, it is possible to suppress the occurrence of a gap between the insertion hole of the closure and the outer circumference of the optical fiber cable 1C due to the unevenness of the protrusions 8. It is possible to suppress the deterioration of the airtightness of the closure. Therefore, the ingress of water into the closure can be suppressed.

(Fourth embodiment)
An optical fiber cable 1D according to the fourth embodiment will be described with reference to FIG. In addition, the same code|symbol is attached|subjected about the structure similar to 1 A of optical fiber cables which concern on said 1st embodiment, and the description is abbreviate|omitted.

FIG. 5 is a cross-sectional view perpendicular to the length direction of the optical fiber cable 1D. As shown in FIG. 5, the optical fiber cable 1D includes a plurality of intermittently connected optical fiber ribbons 2, a water absorbing tape 3 surrounding the optical fiber ribbons 2, and a cable surrounding the water absorbing tape 3. It comprises a jacket 4 (4a, 4b), and a tensile member 5 and a tear string 6 provided inside the cable jacket 4 (4a, 4b).
In addition, although the tensile strength member 5 is illustrated as being the same as the four tensile strength members 5A having a circular cross-sectional view in the optical fiber cable 1A according to the first embodiment, It may be the same as the two plate-like tensile members 5B in cross section in the optical fiber cable 1B.

Furthermore, the optical fiber cable 1D has a plate-like projection 9 in a cross-sectional view that projects from the cable jacket 4 (4a, 4b) in the radial direction of the optical fiber cable 1D. In this example, the cable jacket 4 (4a, 4b) is formed of two layers, an inner layer 4a and an outer layer 4b, and the projecting body 9 is provided so as to protrude from the outer layer 4b. It is A plurality of plate-like protrusions 9 (eight in this example) are provided. The eight plate-shaped protrusions 9 are continuously spirally arranged along the longitudinal direction of the optical fiber cable 1D. In this way, the plate-like projecting body 9 projecting in the radial direction of the optical fiber cable 1D from the outer peripheral portion of the cable jacket 4 (outer layer 4b) spirally along the longitudinal direction of the optical fiber cable 1D. It has an arranged configuration. With this configuration, the side surface of the projecting body 9 becomes a continuous surface along the longitudinal direction so as to be helically twisted along the longitudinal direction while being inclined so as to intersect the radial direction of the optical fiber cable 1D. ing. Therefore, when wind is blown along the longitudinal direction of the optical fiber cable 1D, the air flowing along the longitudinal direction hits the side surface of the protrusion 9, and the protrusion 9 receives wind pressure. Although the example in which the protrusions 9 are arranged continuously along the longitudinal direction has been described here, the protrusions 9 may be intermittently arranged in the longitudinal direction. When intermittently arranged, the cross section of the projecting body can receive wind even if it is not arranged in a spiral shape, but the spirally arranged projecting body is more susceptible to wind pressure.

The eight plate-like protrusions 9 are formed in a plate-like shape curved in a circular arc in a cross-sectional view, and are provided on the outer peripheral portion of the cable jacket 4 at substantially equal intervals. The protruding body 9 is made of a thin plate-shaped resin that is easily deformable and has flexibility. Examples of the material for the projecting body 9 include resins such as low-density polyethylene, which are relatively soft resins, and elastomers. The projections 9 are formed integrally with the outer layer 4b of the cable jacket 4, for example by extrusion. The outer layer 4b of the cable sheath 4 is made of a soft resin with a low Young's modulus, which is the same as that of the projecting body 9, and the inner layer 4a is made of a hard resin with a relatively high Young's modulus so as to function as a protective layer. It has a two-layer structure formed by Other configurations are the same as those of the optical fiber cable 1A.

As described above, the optical fiber cable 1D according to the fourth embodiment has a configuration in which the protruding body 9 is susceptible to wind pressure along the longitudinal direction of the optical fiber cable 1D. is sent, the projecting body 9 receives wind pressure. Thereby, when the optical fiber cable 1D is pneumatically fed in the duct, the pumping distance can be extended.

Also, the projecting body 9 can be deformed by pressing the portion fixed to the closure from the outer periphery, and can be deformed into a radially folded state. Therefore, for example, when the optical fiber cable 1D is inserted into a wiring member such as a closure, it is possible to suppress the occurrence of a gap between the insertion hole of the closure and the outer circumference of the optical fiber cable 1D due to the unevenness of the projecting body 9. It is possible to suppress the deterioration of the airtightness of the closure. Therefore, the ingress of water into the closure can be suppressed.

(Example)
In the optical fiber cable according to the present embodiment, a plurality of samples having different strength members and different numbers thereof were evaluated for pumping distance and storability. Table 1 shows the evaluation results.

In Table 1, sample no. Reference numeral 1 is an optical fiber cable for comparison having a conventional structure in which two tension members each having a circular cross section are embedded in both sides of the cable jacket. Sample no. 2 to 4 have four embedded tensile strength members with a circular cross section, and have the same structure as the optical fiber cable 1A. Sample no. 5 and 6 are two plate-shaped tension members embedded, and have the same structure as the optical fiber cable 1B. As the plate-shaped tensile member, aramid FRP with a diameter of about 0.7 mm and 1.2 mm was flattened in a separate process, formed into a plate, and embedded in the cable jacket during extrusion.
Also, sample no. Tensile members 1 and 2 are glass FRP with an outer diameter of 0.5 mm. Sample no. 3 is an aramid FRP with an outer diameter of 0.5 mm. Sample no. 4 is a glass FRP with an outer diameter of 1.0 mm. Sample no. 5 is an aramid FRP with a thickness of 0.5 mm. Sample no. 6 is aramid FRP with a thickness of 1.0 mm.

The maximum and minimum bending stiffness indicate the bending stiffness value in the direction of maximum bending stiffness and the bending stiffness value in the direction of minimum bending stiffness when each optical fiber cable is bent in the radial direction. The bending stiffness measurement method complies with IEC60794 Stiffness (Method E17A). In the structure of FIG. 1, the flexural rigidity becomes maximum when bent in the direction of the tensile member 5A, and becomes minimum in the direction deviated by 45 degrees from the direction of the tensile member 5A.
For the pumping distance, a microduct pumping test conforming to IEC was performed using the pumping apparatus shown in FIG. The pipe 20 has a length of 1000m and is folded back every 100m. The bend (R) of the pipe 20 is 40 times the outer diameter of the pipe, and the inner diameter of the pipe 20 is 14 mm. Aperture 21 is the inlet for air and fiber optic cable, and aperture 22 is the outlet for air and fiber optic cable. The air pressure was 1.3 MPa to 1.5 MPa.

The pumping distance was evaluated as A when the pumping distance was 1000 m or more, B when the pumping distance was 800 m or more and less than 1000 m, and C when the pumping distance was less than 800 m.
The storability was evaluated by judging whether or not a 5 m bundle could be stored in a 1.2 m cubic space.

According to the evaluation results in Table 1, the samples with a pumping distance of 1000 m or more (samples of evaluation A) were No. It was 2-6. On the other hand, the sample (evaluation C sample) with a pumping distance of less than 800 m was No. was 1. As a result, it was found that pumping of 1000 m or more is possible when the minimum bending stiffness of the optical fiber cable is 0.3 N·m ² or more.

In addition, the samples with good storability are No. 1 to 3.5. On the other hand, the samples with poor storability are No. was 4,6. As a result, when the maximum bending rigidity of the optical fiber cable is 1.5 N·m ² or less, the storability is good, and when the maximum bending rigidity is 3.5 N·m ² or more, the storability is poor. I found out.

Further, in order to further improve the pumping characteristics of the optical fiber cable, the cable jacket 4 was examined. As a result, by adding a silicone-based lubricant to the cable jacket, the coefficient of friction of the cable jacket can be reduced. I found out.

Also, in order to further improve the characteristics of the optical fiber cable, the secondary resin of the optical fiber core wires 11A to 11L was examined. As a result, by blending the inorganic oxide particles into the secondary resin, the lateral pressure characteristics of the optical fiber ribbon can be improved, and the core density can be increased by about 1.0 to 1.5 cores/mm ² . Do you get it.
Also, ITU-T G. A similar effect can be obtained by using an optical fiber core wire equivalent to 657A2.

Although the present invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention. Further, the number, positions, shapes, etc., of the constituent members described above are not limited to those of the above-described embodiment, and can be changed to suitable numbers, positions, shapes, etc. in carrying out the present invention.

1A to 1D: optical fiber cable 2: intermittently connected optical fiber ribbon 3: water absorbing tape 4: cable jacket 4a: inner layer (of cable jacket 4) 4b: outer layer (of cable jacket 4) 5, 5A, 5B: tensile strength member 6: tear string 8: projection 9: projecting body 11A to 11L: optical fiber core wire 12: connecting part 13: non-connecting part 14: connecting resin 15: glass fiber 16: inner coating layer 17: outer coating layer 20: pipe 21, 22: opening

Claims (11)

Among some or all of the optical fiber core wires, a connecting portion where the adjacent optical fiber core wires are connected and a non-connecting portion where the adjacent optical fiber core wires are not connected intermittently in the longitudinal direction The provided intermittently connected optical fiber ribbon,
a cable jacket enclosing a plurality of the optical fiber tape core wires;
two or more tensile strength members provided to be embedded inside the cable jacket;
An optical fiber cable having
The radial bending rigidity of the optical fiber cable is 0.3 N·m ² or more and 1.5 N·m ² or less in the circumferential direction,
The core density obtained by dividing the number of cores of the optical fiber core wire by the cross-sectional area of the cable is 5.0 cores/mm ² or more ,
A ratio of the total cross-sectional area of the plurality of tensile strength members to the cross-sectional area of the cable jacket is 2.4% or more,
fiber optic cable. The number of the tensile strength members is four,
Two pairs of the tensile strength members are provided at positions facing each other across the center of the optical fiber cable in a cross-sectional view,
The positions of the four tensile strength members in a cross-sectional view are the positions where the two straight lines connecting the two tensile strength members that form a pair are perpendicular to each other,
The optical fiber cable of Claim 1. The tensile strength member is a plate-shaped member whose cross section is formed in an arc shape along the curved surface of the cable jacket,
The optical fiber cable of Claim 1. The tensile strength body is a fiber reinforced plastic,
The optical fiber cable according to any one of claims 1-3 . The fiber-reinforced plastic is aramid FRP,
The optical fiber cable according to claim 4 . The cable jacket contains a silicone-based lubricant,
The optical fiber cable according to any one of claims 1-5 . The cable jacket has a protrusion on its outer circumference,
The optical fiber cable according to any one of claims 1-6 . The projection has a curved surface at an end in a direction in which the projection protrudes,
The curvature radius of the curved surface is 2.5 mm or more,
The optical fiber cable of Claim 7 . The protrusion is a plate-shaped protrusion in a cross-sectional view that protrudes in the radial direction of the optical fiber cable,
The protrusions are arranged in a spiral shape continuously along the longitudinal direction of the optical fiber cable,
The optical fiber cable of Claim 7 . The optical fiber core wire has a glass fiber and a coating covering the outer periphery of the glass fiber,
The coating comprises two coating layers,
The outer coating layer of the two coating layers,
a base resin containing a urethane acrylate oligomer or urethane methacrylate oligomer, a monomer having a phenoxy group, a photopolymerization initiator and a silane coupling agent;
A cured product of a resin composition containing hydrophobic inorganic oxide particles,
The content of the inorganic oxide particles in the resin composition is 1% by mass or more and 45% by mass or less based on the total amount of the resin composition.
10. The optical fiber cable according to any one of claims 1-9 . The optical fiber has a bending loss at a wavelength of 1550 nm of 0.5 dB or less with a bending diameter of φ15 mm×1 turn and 0.1 dB or lower with a bending diameter of φ20 mm×1 turn.
11. The fiber optic cable of any one of claims 1-10 .

Images