JP2002243997A - Optical fiber with protective tube, and cord with multi- core ferrule protective tube - Google Patents

Abstract

(57) [Problem] To facilitate the work of inserting or removing an optical fiber into or from an optical fiber protective tube. SOLUTION: Fluororesin tubes are used as optical fiber protection tubes 31, 32 through which optical fiber wires F1, F2 are inserted. [Effect] Friction resistance is reduced, it can be inserted smoothly,
It can be pulled out smoothly, making insertion and removal work easier.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical fiber with a protective tube and a cord with a multi-core ferrule protective tube, and more particularly to inserting or removing an optical fiber into or from an optical fiber protective tube. The present invention relates to an optical fiber with a protection tube and a cord with a multi-core ferrule protection tube having a structure that facilitates work.

[0002]

2. Description of the Related Art Japanese Patent Application Laid-Open No. 2001-021761 discloses a multi-core ferrule having a plurality of parallel optical fiber insertion holes, and a first end inserted into each of the optical fiber insertion holes. A plurality of optical fiber strands, a large-diameter protective tube fitted into the optical fiber strand insertion side end of the multi-core ferrule, and an optical fiber exposed from the optical fiber strand insertion side end of the multi-core ferrule A cord with a multi-core ferrule protection tube including a plurality of optical fiber protection tubes for inserting the wires, and a heat-shrinkable tube connecting the large-diameter protection tube and the optical fiber protection tube is disclosed. ing.

[0003] The optical fiber has an outer diameter of 0.2.
A single-mode optical fiber having a length of 5 mm and a length of 2.5 m is used. As the large-diameter protective tube, a nylon tube having an outer diameter of 1.8 mm, an inner diameter of 1.4 mm, and a length of 0.5 m is used. As the optical fiber protection tube, a nylon tube having an inner diameter of 0.35 mm, an outer diameter of 0.75 mm, and a length of 2.4 m is used. The heat-shrinkable tube has an inner diameter of 2 mm before heat-shrinkage and a length of 5 cm.

[0004]

Problems to be Solved by the Invention
The cord with the multi-core ferrule protection tube disclosed in Japanese Patent No. 21762 has the following problems. (1) When inserting the optical fiber into the optical fiber protective tube, the optical fiber cannot be inserted smoothly, and the insertion work is troublesome. (2) In the process of assembling into an optical device or the like, the optical fiber protection tube is removed.

Accordingly, an object of the present invention is to provide an optical fiber with a protective tube and a multi-core ferrule protective tube having a structure that facilitates the work of inserting and removing the optical fiber into and from the optical fiber protective tube. Is to provide code.

[0006]

According to a first aspect of the present invention, there is provided an optical fiber having a length of at least 1.2 m, and a protection of the optical fiber having a length of at least 1 m through which the optical fiber is inserted. And an optical fiber with a protective tube, wherein the optical fiber protective tube is a fluororesin tube. In the optical fiber with the protective tube according to the first aspect, the fluororesin tube is used as the optical fiber protective tube. Therefore, when the optical fiber is inserted into the optical fiber, the frictional resistance is reduced, so that the optical fiber can be inserted smoothly, and the optical fiber can be disconnected. Without doing
Insertion work becomes easy. Also, when removing, the removal operation can be smoothly performed without disconnection, and the removal operation becomes easy.

As the above-mentioned fluororesin tube, FEP is used.
(4-fluoroethylene-6-fluoropropylene copolymer resin)
Tube, TFE (tetrafluoroethylene resin) tube,
Fully fluorinated polymer tubing, such as PFA (perfluoroalkoxy resin) tubing, or ETFE
(Ethylene-4fluoroethylene copolymer resin) tube,
ECTFE (ethylene-3-fluoroethylene copolymer resin)
Tubes of ethylene copolymer, such as tubes,
PCTFE (ethylene trifluoride) tube, PVD
A tube of a fluorinated homopolymer such as an F (vinylidene fluoride) tube or a PVF (vinyl fluoride resin) tube can be used.

In a second aspect, the present invention provides a multi-core ferrule having a plurality of parallel optical fiber insertion holes, and a plurality of ferrules each having a first end inserted into each of the optical fiber insertion holes. An optical fiber strand, a large-diameter protective tube fitted into the optical fiber strand insertion side end of the multi-core ferrule, and an optical fiber strand exposed from the optical fiber strand insertion side end of the multi-core ferrule And a plurality of small-diameter protective tubes each having a first end inserted into the large-diameter protective tube and fixed to the large-diameter protective tube, and an optical fiber bare exposed from a second end of the small-diameter protective tube. A plurality of optical fiber protection tubes, each of which is inserted and a second end of the small-diameter protection tube is inserted, and each of which is fixed to the small-diameter protection tube. Mamoru tube, to provide a multi-core ferrule protective tube with code which is a fluorine resin tube. In the cord with the multi-core ferrule protection tube according to the second aspect, since a fluororesin tube is used as the optical fiber protection tube, when the fiber is inserted into the fiber, the frictional resistance is reduced, and the fiber can be smoothly inserted. No need to do this, making the insertion work easier. Also, when removing, the removal operation can be smoothly performed without disconnection, and the removal operation becomes easy. Further, since the large-diameter protective tube and the small-diameter protective tube are used, the degree of freedom for adjustment for absorbing the difference in diameter is increased. Since the small diameter protection tube is shorter than the optical fiber protection tube, the operation of inserting the optical fiber into the small diameter protection tube is not a burden.

In a third aspect, the present invention provides the cord with the multi-core ferrule protection tube having the above-mentioned structure, wherein the small-diameter protection tube is a nylon tube, and the small-diameter protection tube and the optical fiber wire protection tube are adhered to each other. Provided is a cord with a multi-core ferrule protection tube, which is fixed by a tape. In the cord with the multi-core ferrule protection tube according to the third aspect, it is not necessary to cut off the heat-shrinkable tube, and the optical fiber protection tube can be removed by peeling off the adhesive tape, thereby facilitating the removal operation. In addition, the fluororesin tube does not easily work with an adhesive, but can be suitably fixed with an adhesive tape.

[0010] In a fourth aspect, the present invention provides the cord with the multi-core ferrule protective tube having the above-mentioned configuration, wherein the large-diameter protective tube is a nylon tube, and the large-diameter protective tube and the small-diameter protective tube are bonded with an adhesive. The present invention provides a cord with a multi-core ferrule protection tube, wherein the cord is secured with a. In the cord with the multi-core ferrule protection tube according to the fourth aspect, the large-diameter protection tube and the small-diameter protection tube are bonded to each other.
It can be removed integrally, making the removal operation easier. In addition, since they are made of nylon, they can be suitably bonded to each other.

In a fifth aspect, the present invention provides a multi-core ferrule having a plurality of parallel optical fiber insertion holes, and a plurality of ferrules each having a first end inserted into each of the optical fiber insertion holes. An optical fiber, a large-diameter protective tube fitted into the optical fiber-inserted end of the multi-core ferrule, and a first end inserted into the large-diameter protective tube and fixed to the large-diameter protective tube. And the optical fiber exposed from the optical fiber insertion end of the multi-core ferrule is inserted therethrough, and the first end is inserted into the medium-diameter protective tube to protect the medium-diameter ferrule. A plurality of optical fiber protection tubes fixed to the tube, wherein the optical fiber protection tube is a fluororesin tube; To provide. In the cord with the multi-core ferrule protection tube according to the fifth aspect, since the fluororesin tube is used as the optical fiber protection tube, when the fiber is inserted into the fiber, the frictional resistance is reduced, and the fiber can be smoothly inserted. No need to do this, making the insertion work easier. Also, when removing, the removal operation can be smoothly performed without disconnection, and the removal operation becomes easy. Further, since the large-diameter protective tube and the medium-diameter protective tube are used, the degree of freedom for adjustment for absorbing the difference in diameter is increased. Since the medium-diameter protection tube is shorter than the optical fiber protection tube, the operation of inserting the optical fiber into the medium-diameter protection tube is not burdensome.

According to a sixth aspect of the present invention, in the cord with the multi-core ferrule protection tube having the above-mentioned structure, the medium-diameter protection tube is a nylon tube, and the medium-diameter protection tube and the optical fiber wire protection tube are combined with each other. The present invention provides a cord with a multi-core ferrule protection tube, wherein the cord is fixed with an adhesive tape. In the cord with the multi-core ferrule protection tube according to the sixth aspect, it is not necessary to cut off the heat-shrinkable tube, and the optical fiber protection tube can be removed by peeling off the adhesive tape. In addition, the fluororesin tube does not easily work with an adhesive, but can be suitably fixed with an adhesive tape.

According to a seventh aspect of the present invention, in the cord with the multi-core ferrule protection tube having the above-described structure, the large-diameter protection tube is a nylon tube, and the large-diameter protection tube and the medium-diameter protection tube are bonded. Provided is a cord with a multi-core ferrule protection tube, which is fixed by an agent. In the cord with the multi-core ferrule protection tube according to the seventh aspect, the large-diameter protection tube and the medium-diameter protection tube are adhered to each other.
It can be removed integrally, making the removal operation easier. In addition, since they are made of nylon, they can be suitably bonded to each other.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in more detail with reference to the embodiments shown in the drawings. Note that the present invention is not limited by this.

First Embodiment FIG. 1 is a sectional view showing a cord 100 with a two-core ferrule protection tube according to a first embodiment of the present invention.
This cord 100 with a two-core ferrule protection tube is
2 provided with a plurality of parallel optical fiber insertion holes 3 and 4
A core ferrule 1, two optical fiber strands F1 and F2 each having a first end inserted into each of the optical fiber strand insertion holes 3 and 4, and an optical fiber strand insertion side of the two-core ferrule 1 The large-diameter protective tube 6 fitted into the end 2B and the optical fiber strands F1, F2 exposed from the optical fiber strand insertion side end 2B of the two-core ferrule 1 are inserted through the large-diameter protective tube 6, respectively. Two small-diameter protective tubes 7, 8 having first ends inserted therein and fixed to the large-diameter protective tube 6, and optical fiber strands F1, F2 exposed from the second ends of the small-diameter protective tubes 7, 8 And two optical fiber protection tubes 31 and 32 respectively having the second ends of the small-diameter protection tubes 7 and 8 inserted therein and fixed to the small-diameter protection tubes 7 and 8, respectively, and measurement terminals 11 and 12. And with And composed.

The optical fibers F1 and F2 are single-mode optical fibers having an outer diameter of 0.25 mm and a length of 2.5 m. The large-diameter protective tube 6 has an outer diameter of 1.8 m.
It is a nylon tube having a diameter of 1.5 m and a length of 4 cm. The small diameter protection tubes 7 and 8 have an outer diameter of 0.75 m.
It is a nylon tube having a diameter of 0.45 mm and a length of 0.5 m. The optical fiber protection tubes 31, 32
Is an FEP with an inner diameter of 1.6 mm, an outer diameter of 2 mm, and a length of 1.5 m
It is a tube.

FIG. 2 is a flowchart showing the steps of manufacturing and shipping the cord 100 with the two-core ferrule protection tube. In the optical fiber measuring and cutting step S1,
The optical fiber is measured and cut to a required length to obtain the optical fiber F1, F2. In the optical fiber protection tube insertion step S2, the optical fiber protection tubes 31 and 32 are inserted through the optical fiber wires F1 and F2, respectively, to obtain an optical fiber with a protection tube. In the small diameter protection tube insertion step S3, the optical fiber wire protection tube 3
The small-diameter protective tubes 7 and 8 are inserted through the optical fiber strands F1 and F2 exposed from the optical fiber strands 1 and 32, respectively, and the second ends of the small-diameter protective tubes 7 and 8 are inserted into the optical fiber strand protective tubes 31 and 32, respectively. And are fixed with adhesive tapes 21 and 22. In the large-diameter protective tube insertion step S4, the first ends of the small-diameter protective tubes 7 and 8 are inserted into the large-diameter protective tube 6 and fixed with the adhesive 10.

In the terminal processing step S5, the optical fiber strand F exposed from the optical fiber strand protection tubes 31, 32 is
Measurement terminals 11 and 12 are connected to the second ends of F1 and F2, respectively. In the ferrule insertion step S6, the first ends of the optical fiber wires F1 and F2 exposed from the large-diameter protective tube 6 are respectively inserted into the optical fiber wire insertion holes 3 and 3 of the two-core ferrule 1.
Insert into 4. At the same time, the two-core ferrule 1 is fitted into the large-diameter protective tube 6. In the adhesive curing step S7, the adhesive 5 is injected into the optical fiber insertion end 2B of the two-core ferrule 1 and cured. In the ferrule end polishing step S8, the tip surface 2A of the two-core ferrule 1 is polished. In the inspection step S9, the cord 1 with the 2-core ferrule protection tube
Inspections such as light transmission measurement and loss measurement of 00 are performed, and those that pass are sent to the packing and shipping process. In the packing and shipping process S10,
The cord 100 with the 2-core ferrule protection tube is packed and shipped.

FIG. 3 is a flowchart showing the steps of receiving and assembling the cord 100 with the two-core ferrule protection tube. In the acceptance inspection process R1, 2
Inspection such as light transmission measurement and loss measurement of the cord 100 with the core ferrule protection tube is performed, and those that pass are accepted. In the protective tube removing step R2, first, the measurement terminal 1
Excises 1,12. Next, the adhesive tapes 21 and 22 are peeled off, and the optical fiber protection tubes 31 and 32 are removed. Next, the large-diameter protective tube 6 and the small-diameter protective tube 7,
And 8 are unified. In the assembling step R3, the optical fiber wires F1 and F2 are housed in a package in a ring shape, the two-core ferrule 1 coming out of the package is connected to an optical device or the like, and the optical fiber wires F1 and F2 coming out of the package are connected. Fusion splicing to another optical fiber.

According to the cord 100 with the two-core ferrule protection tube according to the first embodiment, since the FEP tubes are used as the optical fiber protection tubes 31 and 32, when the fiber wires F1 and F2 are inserted. To
The frictional resistance is reduced, the insertion can be performed smoothly, and there is no disconnection, and the insertion work becomes easy. Also, when removing, the removal operation can be smoothly performed without disconnection, and the removal operation becomes easy.

Further, since the large-diameter protective tube 6 and the small-diameter protective tubes 7 and 8 are used, the degree of freedom of adjustment for absorbing the difference in diameter is increased. In addition, the small-diameter protective tube 7,
8 is shorter than the optical fiber protection tubes 31 and 32, so that the optical fiber F
The work of inserting F1 and F2 is not burdensome.

Further, since it is not necessary to cut off the heat-shrinkable tube, and if the adhesive tapes 21 and 22 are peeled off, the optical fiber protection tubes 31 and 32 can be removed, the removal operation becomes easy. In addition, the FEP tube does not easily work with an adhesive, but the adhesive tapes 21 and 22 can be suitably fixed.

Further, since the large-diameter protective tube 6 and the small-diameter protective tubes 7 and 8 are adhered to each other, they can be integrally removed at the time of removal, thereby facilitating the removal operation. In addition, since they are made of nylon, they can be suitably bonded to each other.

Second Embodiment FIG. 4 is a sectional view showing a cord 200 with a two-core ferrule protection tube according to a second embodiment of the present invention.
The cord 200 with the 2-core ferrule protection tube is
2 provided with a plurality of parallel optical fiber insertion holes 3 and 4
A core ferrule 1, two optical fiber strands F1 and F2 each having a first end inserted into each of the optical fiber strand insertion holes 3 and 4, and an optical fiber strand insertion side of the two-core ferrule 1 A large-diameter protective tube 6 fitted into the end 2B, a medium-diameter protective tube 9 having a first end inserted into the large-diameter protective tube 6 and fixed to the large-diameter protective tube 6;
The optical fiber strands F1 and F2 exposed from the optical fiber strand insertion side end 2B of the core ferrule 1 are inserted, respectively, and the first end is inserted into the middle diameter protection tube 9 and fixed to the middle diameter protection tube 9. The optical fiber protection tubes 31 and 32 and the measurement terminals 11 and 12 are provided.

The optical fibers F1 and F2 are single-mode optical fibers having an outer diameter of 0.25 mm and a length of 2.5 m. The large-diameter protective tube 6 has an outer diameter of 1.8 m.
It is a nylon tube having a diameter of 1.6 mm and a length of 4 cm. The middle-diameter protective tube 9 is a nylon tube having an outer diameter of 1.4 mm, an inner diameter of 1.2 mm, and a length of 0.5 m.
The optical fiber protection tubes 31 and 32 are FEP tubes having an outer diameter of 0.6 mm, an inner diameter of 0.4 mm, and a length of 1.5 m.

FIG. 5 is a flowchart showing the steps of manufacturing and shipping the cord 200 with the two-core ferrule protection tube. In the optical fiber measuring and cutting process P1,
The optical fiber is measured and cut to a required length to obtain the optical fiber F1, F2. In the optical fiber protection tube insertion step P2, the optical fiber protection tubes 31, 32 are inserted through the optical fiber wires F1, F2, respectively, to obtain an optical fiber with a protection tube. In the medium-diameter protective tube insertion step P3, the optical fiber wire protective tube 3
The medium-diameter protective tube 9 is inserted through the optical fiber strands F1 and F2 exposed from the first and second optical fiber strands. Fix at 20. In the large-diameter protective tube insertion step P4, the first end of the medium-diameter protective tube 9 is inserted into the large-diameter protective tube 6 and fixed with an adhesive 10.

In the terminal processing step P5, the optical fiber F exposed from the optical fiber protective tubes 31 and 32 is used.
Measurement terminals 11 and 12 are connected to the second ends of F1 and F2, respectively. In the ferrule insertion step P6, the first ends of the optical fiber wires F1 and F2 exposed from the large-diameter protective tube 6 are respectively inserted into the optical fiber wire insertion holes 3 and 3 of the two-core ferrule 1.
Insert into 4. At the same time, the two-core ferrule 1 is fitted into the large-diameter protective tube 6. In the adhesive curing step P7, the adhesive 5 is injected into the optical fiber insertion end 2B of the two-core ferrule 1 and cured. In the ferrule end polishing step P8, the tip surface 2A of the two-core ferrule 1 is polished. In the inspection process P9, the cord 2 with the 2-core ferrule protection tube
Inspections such as light transmission measurement and loss measurement of 00 are performed, and those that pass are sent to the packing and shipping process. In the packing and shipping process P10,
The cord 200 with the 2-core ferrule protection tube is packed and shipped.

FIG. 6 is a flowchart showing the steps of receiving and assembling the cord 200 with the two-core ferrule protection tube. In the acceptance inspection process Q1, 2
Inspection such as light transmission measurement and loss measurement of the cord 200 with the core ferrule protection tube is performed, and those that pass are accepted. In the protective tube removing step Q2, first, the measurement terminal 1
Excises 1,12. Next, the adhesive tape 20 is peeled off,
The optical fiber protection tubes 31 and 32 are pulled out. Next, the large-diameter protective tube 6 and the medium-diameter protective tube 9 are integrally removed. In the assembling step Q3, the optical fiber F
1 and F2 are housed in a package in a ring shape, the two-core ferrule 1 coming out of the package is connected to an optical device or the like, and the optical fiber strands F1 and F2 coming out of the package are fusion-spliced to other optical fibers.

According to the cord 200 with the two-core ferrule protection tube according to the second embodiment, since the FEP tubes are used as the optical fiber protection tubes 31 and 32, when the fiber F1 and F2 are inserted. To
The frictional resistance is reduced, the insertion can be performed smoothly, and there is no disconnection, and the insertion work becomes easy. Also, when removing, the removal operation can be smoothly performed without disconnection, and the removal operation becomes easy.

Further, since the large-diameter protective tube 6 and the medium-diameter protective tube 9 are used, the degree of freedom for adjustment for absorbing the difference in diameter is increased. Since the medium-diameter protection tube 9 is shorter than the optical fiber protection tubes 31 and 32, the operation of inserting the optical fiber wires F1 and F2 into the medium-diameter protection tube 9 does not burden the user.

In addition, since it is not necessary to cut off the heat-shrinkable tube, and if the adhesive tape 20 is peeled off, the optical fiber protection tubes 31 and 32 can be removed, the removal operation becomes easy. In addition, the FEP tube is difficult for the adhesive to work,
Adhesive tape 20 can be suitably fixed.

Further, since the large-diameter protective tube 6 and the medium-diameter protective tube 9 are adhered to each other, they can be removed integrally when they are removed, thereby facilitating the removal operation. In addition, since they are made of nylon, they can be suitably bonded to each other.

[0033]

According to the optical fiber with the protective tube and the cord with the multi-core ferrule protective tube of the present invention,
Since the fluororesin tube is used as the optical fiber protection tube, when the fiber is inserted, the frictional resistance is reduced, the insertion can be performed smoothly, and the insertion operation is facilitated without breaking. Also, when removing,
It can be pulled out smoothly, without disconnection,
Removal work is easier.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a cord with a multi-core ferrule protection tube according to a first embodiment.

FIG. 2 is a flowchart showing each step of a manufacturing and shipping procedure of the cord with the multi-core ferrule protection tube according to the first embodiment.

FIG. 3 is a flowchart showing each step of a procedure for receiving and installing a cord with a multi-core ferrule protection tube according to the first embodiment.

FIG. 4 is a cross-sectional view of a cord with a multi-core ferrule protection tube according to a second embodiment.

FIG. 5 is a flowchart showing each step of a manufacturing / shipping procedure of a cord with a multi-core ferrule protection tube according to a second embodiment.

FIG. 6 is a flowchart showing each step of a procedure for receiving and installing a cord with a multi-core ferrule protection tube according to a second embodiment.

[Explanation of symbols]

100, 200 Cord with 2-core ferrule protection tube 1 2-core ferrule 6 Large-diameter tube 7, 8 Small-diameter tube 9 Medium-diameter tube 11, 12 Measurement terminal 20, 21, 22 Adhesive tape 31, 32 Optical fiber wire protection tube F1, F2 optical fiber

[Procedure amendment]

[Submission Date] March 28, 2001 (2001.3.2)
8)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0032

[Correction method] Change

[Correction contents]

Further, since the large-diameter protective tube 6 and the medium-diameter protective tube 9 are adhered to each other, they can be removed integrally when they are removed, thereby facilitating the removal operation. In addition, since they are made of nylon, they can be suitably bonded to each other. Note that depending on the product,
If the protective tube 9 is long, reduce friction.
Alternatively, a fluororesin tube may be used.

Claims (7)

[Claims] An optical fiber having a length of 1.2 m or more,
An optical fiber with a protective tube, comprising: an optical fiber protective tube having a length of 1 m or more through which the optical fiber is inserted, wherein the optical fiber protective tube is a fluororesin tube. . 2. A multi-core ferrule provided with a plurality of parallel optical fiber insertion holes, a plurality of optical fiber wires each having a first end inserted into each of the optical fiber insertion holes, The large-diameter protective tube fitted into the optical fiber insertion end of the multi-core ferrule, and the optical fiber exposed from the optical fiber insertion end of the multi-core ferrule are inserted through the large-diameter ferrule, respectively. A plurality of small-diameter protective tubes each having a first end inserted into the protective tube and fixed to the large-diameter protective tube, and an optical fiber exposed from a second end of the small-diameter protective tube are inserted through the small-diameter protective tube. A plurality of optical fiber protection tubes each having a second end inserted therein and fixed to the small-diameter protection tube, wherein the optical fiber protection tube is made of fluororesin. A cord with a multi-core ferrule protection tube characterized by being a tube. 3. The cord with a multi-core ferrule protection tube according to claim 2, wherein the small-diameter protection tube is a nylon tube, and the small-diameter protection tube and the optical fiber protection tube are fixed with an adhesive tape. A cord with a multi-core ferrule protection tube. 4. The cord with a multi-core ferrule protection tube according to claim 3, wherein the large-diameter protection tube is a nylon tube, and the large-diameter protection tube and the small-diameter protection tube are fixed with an adhesive. Features a cord with a multi-core ferrule protection tube. 5. A multi-core ferrule having a plurality of parallel optical fiber insertion holes, a plurality of optical fiber wires each having a first end inserted into each of the optical fiber insertion holes, A large-diameter protective tube fitted into the end of the optical fiber insertion side of the multi-core ferrule, a medium-diameter protective tube having a first end inserted into the large-diameter protective tube and fixed to the large-diameter protective tube; The plurality of optical fibers which are respectively inserted through the optical fiber wires exposed from the optical fiber wire insertion side end of the multi-core ferrule and whose first ends are inserted into the middle diameter protection tube and are fixed to the middle diameter protection tube. A cord with a multicore ferrule protection tube, comprising: a fiber strand protection tube, wherein the optical fiber strand protection tube is a fluororesin tube. 6. The cord with a multi-core ferrule protection tube according to claim 5, wherein the middle-diameter protection tube is a nylon tube, and the middle-diameter protection tube and the optical fiber protection tube are adhered with an adhesive tape. A cord with a multi-core ferrule protection tube. 7. The cord with a multi-core ferrule protection tube according to claim 6, wherein the large-diameter protection tube is a nylon tube, and the large-diameter protection tube and the medium-diameter protection tube are fixed with an adhesive. A cord with a multi-core ferrule protection tube.