JP2002286980A - Optical fiber cord, its manufacturing method, and optical fiber cord with optical connector attached - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical fiber cord which is non-oriented without having directivity against bending, hard to cause buckling, and free of partial twisting of coated optical fiber tapes, and also to provide the manufacturing method. SOLUTION: The optical fiber cord 11 is constituted by covering, with a plastic jacket 14, the outer periphery of a coated optical fiber tape 12, for which a plurality of optical fibers 12a are parallelly arrayed and made into a tape with a common coating 12b. The plastic jacket 14, in its cross section, is formed in a circular shape outside and in a rectangular shape inside without coming into close contact with the coated optical fiber tape 12. Thickness d1 of the plastic jacket 14 on the flat side of the coated optical fiber tape 12 is larger than the thickness d2 of the plastic jacket 14 on the edge side of the tape 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical fiber cord, and more particularly, to an optical fiber cord having a plurality of optical fiber wires arranged in a row and having a tape core, a method of manufacturing the same, and an optical fiber cord with an optical connector. .

[0002]

2. Description of the Related Art With the recent increase in transmission capacity, the construction of optical fiber communication networks has progressed rapidly, and optical connectors have been connected to optical fiber cords in offices and premises from the viewpoint of easy handling. More and more forms are used. Recently, an MT-RJ connector is often used by connecting to an optical fiber cord composed of two optical fiber ribbons. As an optical fiber cord used for this, there is known an optical fiber cord having a structure in which a tensile fiber is longitudinally attached to an optical fiber ribbon and the outside thereof is covered with a thermoplastic resin.

FIG. 5 is a cross-sectional view of a conventionally known optical fiber cord, and FIGS. 5A and 5B.
Fig. 5 (C) and Fig.
(D) shows that the outer surface of the coating is circular. In the figure, 1
a, 1b, 1c, 1d are optical fiber cords, 2a, 2
b, 2c, 2d are optical fiber ribbons, 3a, 3b,
Reference numerals 3c and 3d denote strength members, and reference numerals 4a, 4b, 4c and 4d denote plastic jackets. Optical fiber ribbon 2a, 2
b, 2c, and 2d (hereinafter, referred to as a tape core) are a plurality of optical fiber strands arranged in a row and integrated with a common coating to form a tape. Tape cores 2a, 2b, 2
c, around the tensile strength fiber layers 3a, 3 such as aramid fibers.
b, 3c are attached vertically, and plastic casings 4a, 4b, 4c are formed on the outside thereof by extrusion molding of a plastic material.

The optical fiber cord 1a shown in FIG.
The plastic jacket 4a has an outer surface and an inner surface both having a rectangular cross-sectional shape and a uniform thickness. Although the plastic jacket 4a corresponds to the rectangular cross section of the tape core 2, it is also easy to bend structurally in the plane side of the tape core 2 a and hard to bend in a direction perpendicular to this. Buckling occurs due to the directivity in the bending direction. In particular, in the case of an optical cord with a connector, FIG.
Bent and buckled near the connector as shown in
Often it will not return.

In the optical fiber cord 1b shown in FIG. 5B, the inside of a plastic jacket 4b facing the plane of the tape core wire 2b is formed in a projecting shape (the plastic jacket) in the form of FIG. The thickness is partially increased) to improve the flexibility. However, a jacket 4b of this shape
Is formed, the nipple of the crosshead becomes complicated and productivity is not good. Further, when bent, stress concentrates on the optical fiber in the central portion where the gap between the jacket 4b and the tape core wire 2b is narrowed, and there is a concern that the loss of the optical fiber may increase. Further, buckling is likely to occur at the thin end portions of the outer cover 4b.

The optical fiber cord 1c shown in FIG.
In order to solve the above-mentioned buckling problem, the plastic jacket 4c is formed in a circular shape. This jacket 4
As for c, the cross-sectional shapes of the outer surface and the inner surface are both circular, and the thickness is uniform. This structure is tape core 2
c can rotate freely inside.

The optical fiber cord 1d shown in FIG.
In order to eliminate directivity to bending as in FIG. 5 (C), a jacket 4d is formed in a circular shape, and tensile strength members 3d are arranged on both flat sides of the tape core wire 4 (Japanese Patent Laid-Open No. 2000-2000). 12
1892). However, in this configuration, since the tape core 2d and the tensile strength member 3d are collectively covered with the jacket 4d, the tape core 2d and the jacket 4d are integrated, so that the terminal processing by connector connection or the like is structurally performed. There is a problem that it becomes difficult to do. Further, the optical fiber is subjected to compressive strain when the connector is connected. However, since the tape core 2d and the jacket 4d are integrated, the PC-type connector does not escape springback, and the compressive strain causes the transmission of the optical fiber. Loss increases and disconnection easily occurs.

[0008]

SUMMARY OF THE INVENTION
If the jacket has a rectangular shape and has directivity for bending, wiring must be performed in advance while paying attention to the directivity in the bending direction, which lowers workability and receives external force. When buckled in one direction. In order to improve this point, if the jacket is made circular, as shown in FIG. 6B, when the optical fiber cord 1c is twisted, the tape core 2c is twisted.
Has been found to be subject to concentrated torsion in short sections, which may cause an increase in loss. Particularly, in the case of an optical cord with a connector, an increase in loss is apt to occur, and sometimes the cable is disconnected.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has no directivity to bending, is unlikely to cause buckling, and does not have a twisted tape core wire. It is an object to provide a fiber cord, a method for manufacturing the same, and an optical cord with a connector.

[0010]

According to the present invention, there is provided an optical fiber cord in which a plurality of optical fiber strands are arranged in parallel and the outer periphery of an optical fiber tape core taped by a common coating is covered with a plastic jacket. An optical fiber cord comprising: a plastic jacket having a cross-sectional shape, a circular outer surface and an inner surface formed in a rectangular shape that does not adhere to the optical fiber ribbon, and a plastic envelope on the flat side of the optical fiber ribbon; Is characterized in that it is formed to have a thickness greater than the thickness of the plastic jacket on the edge side of the optical fiber ribbon.

Further, in the method of manufacturing an optical fiber cord according to the present invention, the outer periphery of an optical fiber ribbon obtained by arranging a plurality of optical fibers in parallel and taped by a common coating is covered with a plastic jacket. A method for producing an optical fiber cord comprising: a plastic jacket having a cross-sectional shape, an outer surface having a circular shape, an inner surface having a rectangular shape which is not in close contact with the optical fiber ribbon, and a plastic outer portion on the flat side of the optical fiber ribbon. The plastic jacket is coated and molded in a loose structure so that the thickness of the jacket is larger than the thickness of the plastic jacket on the edge side of the optical fiber ribbon.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to FIG. In the figure, 11 is an optical fiber cord, 12
Indicates a tape core, 13 indicates a tensile strength fiber layer, and 14 indicates a plastic jacket. The optical fiber cord 11 of the present invention has the same basic structure as the conventional one, and aramid fiber is provided around a tape core wire 12 in which a plurality of optical fiber wires 12a are arranged in parallel and integrated in a tape shape with a common coating 12b. And the like, and the outer periphery thereof is covered with a plastic jacket 14.

The tensile strength fiber layer 13 is applied vertically around the ribbon core 12 having a rectangular cross section. The plastic jacket 14 that covers the periphery of the tensile strength fiber layer 13 is formed by coating and molding a cross-sectional shape that has a substantially circular outer surface and a substantially rectangular inner surface. Also, the plastic jacket 14
Is the thickness d1 on the plane side, where d1 is the center of the tape core 12 on the plane side and d2 is the center on the edge side of the tape core.
Is larger than the thickness d2 on the edge side.

The thicknesses d1 and d of the plastic jacket 14
2 depends on the number of cores of the tape core 12, the filling rate of the tensile fiber layer 13, and the finished outer diameter of the plastic jacket 14, but in order to avoid buckling of the tape core in the plane direction,
It is desirable that d1 / d2 be 2 or more. The circular shape of the outer surface of the plastic jacket 14 is circular but need not be a perfect circle, and includes an elliptical shape and a polygonal shape close to a circle. Further, the rectangular inner surface of the plastic jacket 14 does not require that each side of the rectangle is a straight line or that the adjacent side is a right angle, and also includes a case where the shape is close to a rectangle and the corners are arcs. It is a thing.

The optical fiber cord 1 constructed as described above
1 is that the outer shape is substantially circular and the thickness d1 of the plastic jacket 14 on the plane side of the tape core wire 12 increases, so that the cross-sectional area of the tape core wire 12 in the plane direction y increases and the bending rigidity increases. Increase. As a result, the bending stiffness in the plane direction y of the tape core wire 12 is close to the bending stiffness in the edge direction x,
The flexibility biased in the plane direction y is suppressed. Therefore,
The directivity of the optical fiber cord 11 against bending is reduced, and the optical fiber cord 11 does not buckle against an external force. Further, by making the inner surface of the plastic casing 14 substantially rectangular in shape with respect to the plastic casing 14 having a substantially circular shape, the tape core wire 12 is not partially twisted in the plastic casing 14 after molding, and stable transmission is achieved. Characteristics can be maintained.

FIG. 2 is a diagram showing a second embodiment of the present invention. In FIG. 2, in order to completely eliminate the directivity of the optical fiber cord 11 against bending, in addition to the configuration of FIG. 1, the tape core wire 12 and the tensile strength fiber layer 13 are integrally spirally twisted. Things. Note that FIG.
In the figure, the size of the period in the axial direction is shortened for easy understanding of the twisted state. If the rotation cycle is too short, a stress is applied to the tape core 12, and transmission loss increases. On the other hand, if it is too long, it is not possible to obtain omnidirectionality against bending of the optical fiber cord 11.

By making the bending direction of the optical fiber cord 11 omnidirectional, it can be easily and easily bent in any direction during wiring. Therefore, since unnecessary bending and twisting in the wiring direction and the connector arranging direction are not required, an increase in transmission loss does not occur.

FIG. 3 shows a crosshead for coating and molding the plastic jacket 14 of the optical fiber cord 11 of the present invention. FIG. 3 (A) is a cross-sectional view, and FIG. 3 (B) is e-e.
FIG. The crosshead 15 has a shape that covers the plastic jacket 14 with a loose structure, and is aligned so that the positions of the molding ends of the die 16 and the nipple 17 are on the same plane. Point 17 of molding end of nipple 17
a is formed in a rectangular shape, and the hole 16a at the molding end of the die 16 is formed in a circular shape. In the nipple 17, a tensile fiber 13 is vertically inserted around the outer periphery of the tape core wire 12, inserted into the nipple 17, the shape is adjusted at a point 17a of the molding end, and the tape is drawn out at a predetermined linear speed. The coating resin extruded from between the circular hole 16a at the molding end of the die 16 and the point 17a at the molding end of the nipple 17 is extruded to the outer periphery of the tensile strength fiber layer 13, and the plastic jacket 14 is molded in a loose structure. You.

FIG. 3 shows an example in which the tensile strength fibers 13 are longitudinally attached. However, the plastic jacket 14 without the tensile strength fibers may be formed directly on the tape core 12. In the coating molding in which the position of the molding end of the die and the nipple are on the same plane, the coating resin does not exert pressure on the tape core wire, so that it is possible to mold with a loose structure that does not adhere to the tape core wire. . Also, by changing the thickness of the nipple tip and the like, a gap can be provided between the nipple and the core wire.

As shown in FIG. 2, when the tape core 12 is twisted in a spiral to form a coating, the crosshead 15 is rotated by a rotating mechanism (not shown), and the tape core 1 is rotated.
The tape core 12 and the tensile fiber 13 are sent to the crosshead 15 by synchronously rotating the supply mechanism that feeds out the tension fiber 2 and the tensile fiber 13. The optical fiber cord coming out of the rotating crosshead 15 has the tape core 12 as shown in FIG. 2 twisted in a spiral.

FIG. 4 is a diagram showing an example of a fiber cord with an optical connector according to the present invention. A fiber cord with an optical connector is prepared by preparing an optical fiber cord 11 as shown in FIG. 1 or 2 at a predetermined length, and connecting an optical connector 20 to one or both ends thereof. Is done. The optical connector 20 has a multi-core MT-R that is easily detachable.
A J connector can be used. A fiber cord with an optical connector often bends or twists the optical fiber cord near the base of the optical connector 20 when the optical connector is connected to the optical communication device, but the optical fiber cord according to the present invention is used. This prevents buckling due to bending, and also prevents the inner ribbon fiber from being partially twisted in response to the twisting of the optical fiber cord, dispersing evenly and reducing the loss. The increase can be prevented.

Further, a flame-retardant thermoplastic resin can be used for the plastic jacket 14 from the viewpoint of fire prevention. As the flame-retardant thermoplastic resin, there are a case where the base resin itself has flame retardancy, and a case where a flame retardant is added to the base resin to make the base resin flame-retardant. To increase the flame retardancy of resin materials,
Although the use of halogen compounds is extremely useful, the generation of highly corrosive halogen gas during incineration has been considered to contribute to global environmental pollution. Therefore, a halogen-free flame-retardant plastic jacket 14 containing no halogen compound is preferable.

As a specific example of forming the flame-retardant plastic jacket 14, there is a resin obtained by adding a flame retardant such as magnesium hydroxide to an olefin resin such as polyethylene or an ethylene vinyl acetate resin (abbreviation: EVA). It is also possible to use a polyamide resin which is flame-retardant as a coating resin itself, and a polyvinyl chloride resin which is not halogen-free but has excellent flame retardancy. Since the thickness of the plastic jacket on the flat side of the tape core wire 12 is increased, the optical fiber cord of the present invention has a higher proportion of the flame-retardant resin than the conventional optical fiber cord of the same diameter. Increases, which is advantageous for flame retardancy.

Next, returning to FIG. 1, a specific example of the present invention will be described. As the tape core wire 12, the coating outer diameter is 0.25.
mm single mode optical fiber 12a
Were arranged in parallel with a center interval of 0.75 mm, and integrated in a tape shape with a common coating 12b of an ultraviolet curable resin. This tape core wire 12 has a thickness of about 0.31.
mm, the width of the plane is about 1.1 mm.

An aramid fiber (Kevlar trade name) is vertically attached to the periphery of the tape core wire 12, and a coating resin is extruded around the periphery using a crosshead 15 shown in FIG. I do. Plastic jacket 14
The shape of the molded end of the die 16 and the nipple 17 of the crosshead 15 is selected so that the coating form is a loose structure, the outer surface is a circle with a diameter of 3.0 mm, and the inner surface is a rectangle of 1.0 mm x 2.0 mm. did. Therefore, the thickness d1 of the plastic jacket 14 on the plane side of the tape core wire 12 is 1.0 mm.
And the thickness d2 of the plastic jacket 14 on the edge side is 0.5
mm. A non-halogen resin obtained by adding a flame retardant of magnesium hydroxide to a polyolefin-based polyethylene resin was used as a molding material for the plastic jacket 14.

As shown in FIG. 2, the tape core 12 of the optical fiber cord 11 has a helically twisted structure, and its rotation period is 500 mm. At any position of the optical fiber cord 11, the above-described tape core 12
In order to maintain the thickness relationship between the flat side and the edge side, a mechanism for extruding while applying rotation to the crosshead 15 is used, and the supply device for feeding out the tape core wire 12 and the tensile fiber 13 also rotates in synchronization. A manufacturing apparatus was used.

When the optical transmission loss of the optical fiber cord formed as described above was measured, it was as good as 0.20 dB / km at a wavelength of 1.55 μm. Moreover, when it was forcibly bent by hand, it was good without buckling as shown in FIG. Further, a repeated bending test according to JIS C6821 6.4.1 was performed, and it was confirmed that no crack was generated in the plastic jacket and that there was no problem in light transmission characteristics. Further, the optical fiber cord could be bent in any direction. JIS 30 for flame retardancy evaluation
The 60 ° tilt test shown in FIG. 05 was successful.

In the specific example, two tapes are used. However, the present invention is not limited to this, and it is apparent that the present invention can be applied to tapes such as four and eight. The thickness d1 of the plastic jacket on the flat side of the tape core, the thickness d2 of the plastic jacket on the edge side of the tape core, and the finished outer diameter of the plastic jacket are determined by the desired tape core form, tensile strength, and the like. The value is not limited to the above-mentioned value since it changes depending on the filling rate of the fiber.

[0029]

As is apparent from the above description, according to the present invention, the rigidity of the ribbon in the planar direction of the ribbon is increased, and the directivity of the optical fiber cord in the bending direction is reduced. Can also be bent. As a result, wiring can be easily performed without excessive twisting or bending, and transmission loss does not increase.
Further, bending to buckling hardly occurs, and breakage of the optical fiber can be prevented. In particular, in an optical fiber cord with an optical connector, since the tape core wire and the jacket are not in close contact with each other, it is possible to reduce the possibility of an increase in transmission loss and breakage.

[Brief description of the drawings]

FIG. 1 is a diagram showing a cross section of an optical fiber cord of the present invention.

FIG. 2 is a diagram showing another embodiment of the present invention.

FIG. 3 is a view showing a crosshead used for manufacturing the optical fiber cord of the present invention.

FIG. 4 is a diagram showing an optical fiber cord with an optical connector according to the present invention.

FIG. 5 is a diagram showing a cross section of a conventional optical fiber cord.

FIG. 6 is a diagram illustrating a buckling state and a twist of the optical fiber cord.

[Explanation of symbols]

11: Optical fiber cord, 12: Tape core, 13: Tensile fiber layer, 14: Plastic jacket, 15: Crosshead, 16: Die, 17: Nipple, 20: Optical connector.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Yoshiyasu Hongo 1-chome, Tayacho, Sakae-ku, Yokohama-shi, Kanagawa F-term in Yokohama Works, Sumitomo Electric Industries, Ltd. (Reference) 2H001 BB15 BB25 DD06 DD10 DD32 FF07 KK08 KK17 PP01

Claims (7)

[Claims] 1. An optical fiber cord comprising a plurality of optical fiber wires arranged in parallel and taped by a common coating, and an outer periphery of an optical fiber tape core covered with a plastic jacket. The sheath has a cross-sectional shape, an outer surface is formed in a rectangular shape in which the outer surface is circular and the inner surface is not in close contact with the optical fiber ribbon, and the thickness of the plastic jacket on the flat side of the optical fiber ribbon is the optical fiber. An optical fiber cord formed to be larger than the thickness of the plastic jacket on the edge side of the tape core wire. 2. The optical fiber cord according to claim 1, wherein a tensile fiber is longitudinally added between the plastic jacket and the ribbon. 3. When the thickness of the plastic jacket on the flat side of the optical fiber ribbon is d1, and the thickness of the plastic jacket on the edge side of the optical fiber ribbon is d2, d1 / d2 is The optical fiber cord according to claim 1, wherein the number is two or more. 4. The optical fiber cord according to claim 1, wherein the optical fiber ribbon is spirally twisted. 5. The plastic casing according to claim 1, wherein said plastic casing is made of a flame-retardant thermoplastic resin.
The optical fiber cord according to any one of the above. 6. A method for manufacturing an optical fiber cord comprising a plurality of optical fiber wires arranged in parallel and an outer periphery of an optical fiber tape core taped by a common coating is covered with a plastic jacket. The plastic jacket has a cross-sectional shape, the outer surface has a circular shape, and the inner surface has a rectangular shape that does not adhere to the optical fiber ribbon, and the thickness of the plastic jacket on the flat side of the optical fiber ribbon is the light thickness. A method for manufacturing an optical fiber cord, comprising: coating a plastic jacket with a loose structure so as to be larger than the thickness of the plastic jacket on the end side of a fiber ribbon. 7. An optical fiber cord with an optical connector, wherein an optical connector is connected to at least one end of the optical fiber cord according to claim 1.