JP2018031887A - Optical fiber cable - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical fiber cable that exhibits a satisfactory property of cable insertion into thin piping and can be mounted with high density.SOLUTION: An optical fiber cable comprises: a tension member 2 provided at the center thereof; optical fiber ribbons 3 disposed being twisted together around the tension member 2; and a cable sheath 5 for covering an outside of the optical fiber ribbons 3. In the optical fiber ribbons 3, coupling portions formed by coupling a portion between adjacent coated optical fibers 31 and non-coupling portions formed by not coupling the portion between the adjacent coated optical fibers are intermittently provided in a lengthwise direction in a part or all of the portion between the coated optical fibers 31 with the plurality of coated optical fibers 31 disposed in parallel. The optical fiber ribbons 3 are enclosed by an intermediate layer 4 formed with an expandable resin or a jelly-like substance between the tension member 2 and the cable sheath 5, and the cable sheath 5 is made of thermoplastic resin.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an optical fiber cable.

  2. Description of the Related Art As a cable used in an optical fiber home data communication service (FTTH: Fiber To The Home), a trunk optical fiber cable and an optical fiber cable wired in a pipe are known. For example, Patent Document 1 describes a loose tube type optical fiber cable. Patent Document 2 describes a slotless optical fiber cable.

Special table 2015-517679 gazette JP 2010-8923 A

Loose tube type cable has a tension member such as FRP at the center, so there is no bending direction and good wiring to the pipe. However, since each tube is covered with a coating, the outer diameter of the cable increases and the optical fiber High-density mounting of the core wire is difficult.
On the other hand, since the slotless type optical fiber cable does not use a tube, the outer diameter of the cable can be reduced and high-density mounting of the optical fiber core wire is easy. However, in the slotless type optical fiber cable, the tension member is not disposed at the center, and is disposed at, for example, two places in the cable jacket. For this reason, bending directionality arises in an optical fiber cable, and when passing through a pipe, the optical fiber cable is twisted. Therefore, it is difficult to pass through a thin pipe (such as a duct).

  An object of the present invention is to provide an optical fiber cable that has good lineability into a thin pipe and can be mounted at high density.

An optical fiber cable according to one aspect of the present invention is provided.
A tension member provided in the center,
An optical fiber ribbon disposed in a twisted manner around the tension member;
A cable jacket covering the outside of the optical fiber ribbon,
The optical fiber ribbon is a connecting portion in which a plurality of optical fibers are arranged in parallel and a part or all of the optical fibers are connected between adjacent optical fibers. And an unconnected portion that is not connected between adjacent optical fiber core wires is intermittently provided in the longitudinal direction,
The optical fiber ribbon is wrapped in a layer formed between the tension member and the cable jacket by a foamable resin or a jelly-like substance,
The cable jacket is a thermoplastic resin.

  According to the above invention, it is possible to provide an optical fiber cable that has good lineability into a thin pipe and can be mounted at high density.

It is sectional drawing of the optical fiber cable which concerns on this embodiment. It is a figure which shows an example of the optical fiber tape core wire accommodated in an optical fiber cable. It is a schematic diagram of the longitudinal direction of the optical fiber cable shown in FIG.

(Description of Embodiment of the Present Invention)
First, embodiments of the present invention will be listed and described.
An optical fiber cable according to one aspect of the present invention is provided.
(1) a tension member provided in the center,
An optical fiber ribbon disposed in a twisted manner around the tension member;
A cable jacket covering the outside of the optical fiber ribbon,
The optical fiber ribbon is a connecting portion in which a plurality of optical fibers are arranged in parallel and a part or all of the optical fibers are connected between adjacent optical fibers. And an unconnected portion that is not connected between adjacent optical fiber core wires is intermittently provided in the longitudinal direction,
The optical fiber ribbon is wrapped in a layer formed between the tension member and the cable jacket by a foamable resin or a jelly-like substance,
The cable jacket is a thermoplastic resin.

  According to the configuration of (1) above, a so-called intermittently connected optical fiber tape core wire in which a connecting portion and a non-connecting portion are intermittently provided in the longitudinal direction is twisted around the tension member. Therefore, high-density mounting in an optical fiber cable is possible. The optical fiber ribbon is wrapped in a layer formed of a foamable resin or a jelly-like substance, and this layer functions as a buffer layer that weakens damage when the optical fiber cable is bent. . Further, since the tension member is provided at the center, the lineability is good. As described above, the present optical fiber cable has good lineability into a thin pipe and can be mounted at high density.

(2) It is preferable that the thermoplastic resin of the cable jacket has a Young's modulus of 500 Pa or more.
Since the thermoplastic resin of the cable jacket has a Young's modulus of 500 Pa or more, the lateral pressure resistance when the optical fiber cable is bent can be enhanced.

(3) It is preferable that 2 wt% or more of a lubricant is added to the thermoplastic resin of the cable jacket.
Since 2 wt% or more of the lubricant is added to the cable jacket, the lineability is further improved.

(4) The tension member is preferably glass FRP.
Since FRP is a non-derivative, it is not easily affected by lightning. Further, since the FRP is a glass FRP, it is relatively light. For example, when passing through a thin pipe, it can be pneumatically fed.

(5) The layer between the tension member and the cable jacket is formed of a foamable resin,
The foamable resin preferably has a shear strength of 0.1 MPa to 15 MPa.
Since the shear strength of the layer formed between the tension member and the cable jacket by the foamable resin is 0.1 MPa or more and 15 MPa or less, it is easy to use without using a special tool or the like at the time of intermediate branching of the optical fiber cable. In addition, a single-core optical fiber can be taken out from the optical fiber cable.

(Details of the embodiment of the present invention)
Specific examples of the optical fiber cable according to the embodiment of the present invention will be described below with reference to the drawings.
In addition, this invention is not limited to these illustrations, is shown by the claim, and intends that all the changes within the meaning and range equivalent to a claim are included.

FIG. 1 shows a cross section of an optical fiber cable 1 according to the present embodiment as viewed from the longitudinal direction.
As shown in FIG. 1, the optical fiber cable 1 includes a tension member 2 provided at the center, an intermediate layer 4 provided on the outer peripheral side of the tension member 2, and a plurality of sheets disposed in the intermediate layer 4. Optical fiber ribbon 3 and a cable jacket 5 provided on the outer peripheral side of the intermediate layer 4.

  The tension member 2 includes a main body portion 2a and a covering portion 2b provided on the outer peripheral side of the main body portion 2a. The main body 2a is made of, for example, glass fiber reinforced plastic (glass FRP: Glass Fiber Reinforced Practices). The covering portion 2b is made of, for example, low density polyethylene.

  One optical fiber ribbon 3 is composed of a plurality of optical fibers 31. Each optical fiber ribbon 3 is twisted and arranged around the tension member 2.

  The intermediate layer 4 is a layer having a buffer function provided between the tension member 2 and the cable jacket 5, and is formed of a foamable resin or a jelly-like substance. The intermediate layer 4 is provided so as to wrap the optical fiber tape core wire 3 disposed around the tension member 2 inside.

  When the intermediate layer 4 is formed of a foamable resin, the shear strength of the foamable resin is formed to be, for example, 0.1 MPa or more and 15 MPa or less. If the shear strength is 15 MPa or less, the foamable resin can be easily torn by hand. On the other hand, if the shear strength is 0.1 MPa or more, it is possible to suppress breakage of the foamable resin in the cable forming process.

  As the foamable resin, for example, polyolefin such as polyethylene to which 3 wt% or more of a foaming agent is added may be used. For example, polyurethane or polystyrene may be used instead of polyolefin. In such a foamable resin, when the foamability is lowered, the shear strength is lowered. Conversely, when the foamability is raised, the shear strength is increased. For example, in order to set the shear strength of the foamable resin to 15 MPa, the foaming rate may be about 80%, and in order to set the shear strength to 0.1 MPa, the foaming rate may be about 20%. In order to achieve the desired foaming ratio of the foamable resin, for example, the temperature condition may be appropriately adjusted when the intermediate layer 4 is extruded. The foaming rate [%] is defined as [density of resin after extrusion (after foaming)] / [density of original material (pellet)] × 100.

  The cable jacket 5 is formed of a thermoplastic resin such as high-density polyethylene, for example. The thermoplastic resin preferably has a Young's modulus of 500 Pa or more. The cable jacket 5 may be formed of, for example, polybutylene terephthalate, polyvinyl chloride, or the like. The cable jacket 5 may be, for example, low-density polyethylene, but the Young's modulus needs to be a value as described above.

  It is preferable that the thermoplastic resin constituting the cable jacket 5 contains, for example, a silicon-based lubricant. When the silicone-based lubricant is contained in the thermoplastic resin, it is preferably added at a ratio of 2 wt% or more with respect to the thermoplastic resin.

  As specific dimensions of the optical fiber cable 1, for example, the outer diameter R1 of the tension member 2 is 2.0 mm, the outer diameter R2 of the intermediate layer 4 is 3.4 mm, and the outer diameter R3 of the optical fiber cable 1 is 5.0 mm. The thing which was done is mentioned.

  As shown in FIG. 2, the optical fiber tape core 3 has, for example, twelve optical fiber cores 31A to 31L arranged in parallel. Each of the optical fiber cores 31A to 31L is a single-core coated optical fiber, and for example, a glass fiber composed of a core and a clad is covered with a resin. The optical fiber cores 31A to 31L may be coated with different colors so that the optical fiber cores can be distinguished from each other.

  The optical fiber tape core 3 is an intermittently connected optical fiber tape core, and in a state where a plurality of optical fiber cores are arranged in parallel, a connecting portion 3a in which adjacent optical fiber cores are connected to each other; The non-connecting portion 3b where the adjacent optical fiber core wires are not connected is intermittently provided in the longitudinal direction. Thus, the location where the connection part 3a and the non-connection part 3b are provided intermittently may be between some optical fiber cores, or between all optical fiber cores. Also good. In the example shown in FIG. 2, the non-connecting portion 3b is not provided between the optical fiber core wires 31A and 31B, 31C and 31D, 31E and 31F, 31G and 31H, 31I and 31J, and 31K and 31L.

  In addition, the optical fiber tape core wire 3 intermittently connects the connecting portion 3a and the non-connecting portion 3b by, for example, applying a connecting resin such as an ultraviolet curable resin or a thermosetting resin between the optical fiber core wires. Alternatively, it may be formed as a typical method. Alternatively, by applying a connecting resin to the plurality of optical fiber cores 31A to 31L and connecting all the optical fiber core wires, by cutting a part with a rotary blade or the like to make the non-connecting portion 3b, An intermittently connected optical fiber ribbon 3 may be produced.

FIG. 3 is a schematic view in the longitudinal direction of the optical fiber cable 1 shown in FIG.
As shown in FIG. 3, the optical fiber ribbon 3 is wound around the tension member 2 in a spiral shape, for example. For example, in the optical fiber cable 1 of FIG. 1, four optical fiber ribbons 3 (4 × 12 = 48 optical fibers 31) are wound around the tension member 2. The intermittently connected optical fiber ribbons 3 having the connecting portions 3 a and the non-connecting portions 3 b are twisted and wound around the tension member 2.

  According to the optical fiber cable 1 having such a configuration, since the tension member 2 is provided at the center portion, the optical fiber cable 1 has no bending directionality, and has good lineability to a thin pipe or the like. Moreover, since the main body 2a of the tension member 2 is formed of glass fiber reinforced plastic that is a non-derivative, it is not easily affected by lightning, for example. Furthermore, since glass fiber reinforced plastic is comparatively light, it can be pneumatically fed, for example, when it is passed through a thin pipe.

  In addition, an intermittently connected optical fiber ribbon 3 in which connecting portions 3 a and non-connecting portions 3 b are provided intermittently in the longitudinal direction is disposed around the tension member 2 in a twisted manner. Since the intermittently connected optical fiber ribbon 3 is excellent in bending flexibility, when the optical fiber ribbon 3 is twisted together, the optical fibers 31 can be closely adhered to each other without any gap. For this reason, the optical fiber core wire 31 can be mounted with high density.

  Moreover, the optical fiber tape core wire 3 arranged by twisting around the tension member 2 is wrapped in an intermediate layer 4 formed of a foamable resin or a jelly-like substance. The intermediate layer 4 functions as a buffer layer that weakens pressure damage due to bending when the optical fiber cable 1 is bent. For this reason, the optical fiber tape core wire 3 can be protected by the intermediate layer 4 covering the periphery of the optical fiber tape core wire 3.

Further, by making the thermoplastic resin constituting the cable jacket 5 a resin having a Young's modulus of 500 Pa or more, the lateral pressure resistance when the optical fiber cable 1 is bent can be enhanced. In addition, by adding 2 wt% or more of the lubricant to the thermoplastic resin, the coefficient of friction with the external member can be reduced, and the optical fiber cable 1 can be further improved in the piping and the like.
As described above, the optical fiber cable 1 has good lineability into a thin pipe and can be mounted at high density.

  Moreover, the shear strength of the foamable resin constituting the intermediate layer 4 is, for example, 0.1 MPa or more and 15 MPa or less. For this reason, for example, at the time of intermediate branching of the optical fiber cable 1, the operator can easily tear the intermediate layer 4 by hand without using a special tool. Therefore, for example, a desired single optical fiber core wire 31 can be easily taken out from the optical fiber cable 1, and the working efficiency of the operator can be improved.

  While the 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. In addition, the number, position, shape, and the like of the constituent members described above are not limited to the above-described embodiments, and can be changed to a number, position, shape, and the like that are suitable for carrying out the present invention.

DESCRIPTION OF SYMBOLS 1 Optical fiber cable 2 Tension member 2a Body part 2b Covering part 3 Optical fiber tape core wire 3a Connection part 3b Non-connection part 4 Intermediate layer 5 Cable jacket 31 (31A-31L) Optical fiber core wire R1, R2, R3 Outer diameter

Claims (5)

A tension member provided in the center,
An optical fiber ribbon disposed in a twisted manner around the tension member;
A cable jacket covering the outside of the optical fiber ribbon,
The optical fiber ribbon is a connecting portion in which a plurality of optical fibers are arranged in parallel and a part or all of the optical fibers are connected between adjacent optical fibers. And an unconnected portion that is not connected between adjacent optical fiber core wires is intermittently provided in the longitudinal direction,
The optical fiber ribbon is wrapped in a layer formed between the tension member and the cable jacket by a foamable resin or a jelly-like substance,
The cable jacket is an optical fiber cable made of a thermoplastic resin.   The optical fiber cable according to claim 1, wherein the thermoplastic resin of the cable jacket has a Young's modulus of 500 Pa or more.   The optical fiber cable according to claim 1 or 2, wherein a lubricant is added to the thermoplastic resin of the cable jacket in an amount of 2 wt% or more.   The optical fiber cable according to any one of claims 1 to 3, wherein the tension member is a glass FRP. The layer between the tension member and the cable jacket is formed of a foamable resin,
The optical fiber cable according to any one of claims 1 to 4, wherein the foamable resin has a shear strength of 0.1 MPa to 15 MPa.

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