Fan-out cord and pipe cord

Abstract

To provide a fan-out cord in which a single-core coated optical fiber is easily inserted into a ferrule while suppressing transmission loss of light under low temperature.SOLUTION: A multi-core cord (10) including a part of each of a plurality of single-core covered optical fibers (11), a plurality of pipe cords (20) each including another part of any one of the plurality of single-core covered optical fibers (11), and a connecting portion (30) disposed between the multi-core cord (10) and the plurality of pipe cords (20), wherein the pipe cord (20) includes a tube (21) accommodating the single-core covered optical fibers (11), and a cross-sectional area of an internal space of the tube (21) is A, when a cross-sectional area of the single-core covered optical fiber (11) is a, A / a is more than 1.96 and less than 7.84.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to fanout codes and pipe codes. [Background technology]

[0002] A fan-out cord is known that branches a multi-core cord into multiple pipe cords. In the fan-out cord, one multi-core cord has multiple mono-coated optical fibers. Meanwhile, each of the multiple pipe cords has one mono-coated optical fiber branched from the multi-core cord and functions as a mono-core cord. A ferrule is attached to the end of the pipe cord, into which the end of the mono-coated optical fiber is inserted. The ferrule functions as part of a connector for optically connecting the mono-coated optical fiber to another component. For example, Patent Document 1 discloses such a fan-out cord. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-151396 Summary of the Invention [Problem to be solved by the invention]

[0004] The pipe cord of the fan-out cord includes a single-coated optical fiber, a tube that houses the single-coated optical fiber, and a reinforcing material and jacket surrounding the tube. In this pipe cord, the tube shrinks at low temperatures. When the tube shrinks, the tube and the single-coated optical fiber are more likely to come into contact with each other, making microbends more likely to occur in the single-coated optical fiber. When microbends occur, light transmitted through the single-coated optical fiber is not transmitted properly, which can result in optical transmission loss.

[0005] Therefore, it is conceivable to increase the inner diameter of the tube so that the mono-coated optical fiber and the tube do not come into contact with each other, so that no transmission loss of light occurs even when the tube shrinks. However, if the inner diameter of the tube is made too large, it becomes difficult to insert the end of the mono-coated optical fiber into the ferrule.

[0006] An object of the present invention is to provide a fan-out cord that allows a mono-coated optical fiber to be easily inserted into a ferrule while suppressing optical transmission loss at low temperatures, and a pipe cord used in the fan-out cord. [Means for solving the problem]

[0007] In order to solve the above problem, according to one aspect of the present invention, a multi-core cord including a portion of each of a plurality of mono-coated optical fibers; a plurality of pipe cords each including another portion of one of the plurality of mono-coated optical fibers; a connection portion disposed between the multi-core cord and the plurality of pipe cords; and the pipe cord includes a tube that accommodates the mono-coated optical fiber, When the cross-sectional area of ​​the inner space of the tube is A and the cross-sectional area of ​​the mono-coated optical fiber is a, A / a is greater than 1.96 and less than 7.84. A fanout code is provided.

[0008] According to another aspect of the present invention, in order to solve the above problem, A pipe code is provided for use with the above fanout code. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a fan-out cord that allows a single-coated optical fiber to be easily inserted into a ferrule while suppressing optical transmission loss at low temperatures, and a pipe cord used in the fan-out cord. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1A is a diagram showing a fan-out cord, FIG. 1B is a cross-sectional view of a multi-core cord, and FIG. 1C is a cross-sectional view of a pipe cord. [Figure 2] FIG. 2A is a cross-sectional view of a covering portion that covers the connection portion of the fan-out cord, and FIG. 2B is a cross-sectional view of a ferrule connected to the end of the pipe cord. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, a cable manufacturing apparatus according to an embodiment of the present invention will be described, but the cable manufacturing apparatus of the present invention is not limited to the following embodiment.

[0012] [Fanout Code] Fig. 1A is a plan view schematically showing a fan-out cord 1. As shown in Fig. 1A, the fan-out cord 1 has one multi-core cord 10, multiple pipe cords 20, and a connection portion 30 between the multi-core cord 10 and the multiple pipe cords 20. In this embodiment, a ferrule 40 is attached to an end of the pipe cord 20 of the fan-out cord 1.

[0013] Fig. 1B is a cross-sectional view of the multi-core cord 10 taken along line BB in Fig. 1A, and Fig. 1C is a cross-sectional view of the pipe cord 20 taken along line CC in Fig. 1A. As shown in Fig. 1B, the multi-core cord 10 has a plurality of mono-coated optical fibers 11.

[0014] 1C, the pipe cord 20 has one mono-coated optical fiber 11. In the fan-out cord 1, each of the mono-coated optical fibers 11 of the multi-core cord 10 is branched at the splice section 30 so that each of the multiple pipe cords 20 has one mono-coated optical fiber 11. As a result, the pipe cord 20 has one mono-coated optical fiber 11 and is single-core. A ferrule 40 into which the end of the mono-coated optical fiber 11 is inserted is disposed at the end of the pipe cord 20. The ferrule 40 into which the end of the mono-coated optical fiber 11 is inserted functions as part of a connector for optically connecting the mono-coated optical fiber 11 to another member. The following describes in detail each component of the fan-out cord 1.

[0015] (multi-core cord) 1B, the multi-core cord 10 has a plurality of mono-coated optical fibers 11, a reinforcing material 12, and an outer jacket 13. In this embodiment, the multi-core cord 10 is a ribbon cord.

[0016] A plurality of mono-coated optical fibers 11 are coated with a resin layer 11a to form a ribbon core. The resin layer 11a is, for example, a layer formed from an ultraviolet-curable resin. The number of mono-coated optical fibers 11 is not particularly limited as long as there is more than one. The number of mono-coated optical fibers 11 is, for example, two, three, or four. The mono-coated optical fiber 11 has a central core, a cladding located around the core, and a coating portion that coats the cladding, and is a single core. The optical fiber consisting of a cladding and a core may be either single-mode or multi-mode.

[0017] The reinforcing material 12 is disposed around the plurality of mono-coated optical fibers 11 to reinforce the plurality of mono-coated optical fibers 11. Examples of the reinforcing material 12 include fibrous materials. Examples of the fibrous materials include aramid fiber (registered trademark: Kevlar).

[0018] The outer jacket 13 is disposed around the reinforcing material 12. The outer jacket 13 is formed, for example, by extruding a resin around the reinforcing material 12. Examples of the resin include a thermoplastic resin. In this embodiment, the thermoplastic resin is polyethylene.

[0019] (pipe code) 1C , the pipe cord 20 has a mono-coated optical fiber 11, a tube 21, a reinforcing material 22, and an outer jacket 23. In the pipe cord 20, the resin layer 11a coating the mono-coated optical fiber 11 is physically removed to separate the mono-coated optical fibers 11 connected in the width direction, and then further removed using a solvent. Therefore, in the pipe cord 20, the mono-coated optical fiber 11 is not coated with the resin layer 11a.

[0020] That is, the mono-coated optical fiber 11 in the pipe cord 20 is formed by removing the resin layer 11a from the plurality of mono-coated optical fibers 11 that are covered with the resin layer 11a to form a ribbon core wire as described above.

[0021] The tube 21 accommodates the mono-coated optical fiber 11. In this embodiment, the tube 21 has a cylindrical shape. The tube 21 contains, for example, a resin. Examples of the resin include polyethylene terephthalate (PET), polybutylene terephthalate (PBT), nylon, etc. Examples of the nylon include nylon 66 and nylon 12. Of these, nylon 12 is particularly preferable.

[0022] The tube 21 is configured as follows from the viewpoint of suppressing optical transmission loss when the tube 21 shrinks at low temperatures. That is, when the cross-sectional area of ​​the internal space of the tube 21 is A and the cross-sectional area of ​​the mono-coated optical fiber 11 is a, the tube 21 is configured so that A / a exceeds 1.96. In this way, even if the tube 21 shrinks, contact between the tube 21 and the mono-coated optical fiber 11 is suppressed, and optical transmission loss is suppressed. Here, the cross-sectional area A of the internal space of the tube 21 is πR when the internal diameter of the tube is 2R (when half of the internal diameter is R). 2 On the other hand, the cross-sectional area a of the mono-coated optical fiber 11 is calculated by πr where the diameter of the mono-coated optical fiber 11 is 2r (radius is r). 2 It can be calculated as follows.

[0023] The larger A / a is, the more the mono-coated optical fiber 11 is prevented from coming into contact with the tube 21, thereby suppressing the transmission loss of light. On the other hand, if A / a is too large, it becomes difficult to insert the mono-coated optical fiber 11 protruding from the end of the pipe cord 20 into the ferrule 40. Therefore, A / a must be less than 7.84. Details will be described later while showing the structure of the ferrule 40.

[0024] From the viewpoint of suppressing the transmission loss of light, A / a is more preferably 2.1 or more, and even more preferably 2.5 or more. On the other hand, from the viewpoint of facilitating insertion of the mono-coated optical fiber 11 into the ferrule 40, A / a is more preferably 4 or less, and even more preferably 3 or less. The inner diameter of the tube 21 is, for example, 0.35 to 0.70 mm, and the outer diameter is 0.8 to 1 mm. In this embodiment, the inner diameter of the tube 21 is about 0.4 mm, and the outer diameter is about 0.9 mm±0.05 mm.

[0025] The reinforcing material 22 is disposed around the tube 21 to reinforce the mono-coated optical fiber 11 and the tube 21. The reinforcing material 22 can be made of the same fiber material as the reinforcing material 12 of the multi-core cord 10 described above. The outer jacket 23 is extruded around the reinforcing material 22. The outer jacket 23 can be made of the same resin as that used for the outer jacket 13 of the multi-core cord 10 described above.

[0026] (Connection) FIG. 2A shows a longitudinal cross section of the splice 30. In FIG. 2A, only the cross section of the splice 30 is shown, and the outer surfaces of the multi-core cord 10 and the multiple pipe cords 20 are shown. As shown in FIG. 2A, the splice 30 is disposed between the multi-core cord 10 and the multiple pipe cords 20. As shown in FIG. 2A, the splice 30 has a sealing material 31, a first coating portion 32, and a second coating portion 33. In the region between the multi-core cord 10 and the pipe cord 20 in the splice 30, the multiple mono-coated optical fibers 11 are not covered by the reinforcing material 12 and the jacket 13 of the multi-core cord 10, nor by the tube 21, the reinforcing material 22, and the jacket 23 of the pipe cord 20, and are exposed. Furthermore, in the splice 30, the mono-coated optical fibers 11 are not covered by the resin layer 11a.

[0027] The sealing material 31 seals the periphery of the exposed mono-coated optical fiber 11 at the splice portion 30. By sealing the periphery of the mono-coated optical fiber 11 with the sealing material 31, movement of the mono-coated optical fiber 11 is suppressed, making it less likely that microbends will occur, and suppressing the occurrence of optical transmission loss. Details will be described later with reference to examples. There are no particular restrictions on the sealing material 31 as long as it can suppress movement of the mono-coated optical fiber 11 by sealing it. In this embodiment, the sealing material 31 seals the ends of the multi-core cord 10 and the ends of the plurality of pipe cords 20, in addition to the plurality of mono-coated optical fibers 11. Examples of the sealing material 31 include molding materials. Examples of molding materials include adhesives, thermoplastic resins, etc. Examples of adhesives include one-component adhesives, two-component mixed adhesives, etc. Examples of thermoplastic resins include polyethylene, EVA (ethylene vinyl acetate), etc.

[0028] The first coating portion 32 coats the sealing material 31. More specifically, the first coating portion 32 coats the end of the multi-core cord 10, the ends of the multiple pipe cords 20, the multiple mono-coated optical fibers 11 between them, and the sealing material 31 that seals them. In this embodiment, the first coating portion 32 is a hollow member, specifically a pipe. From the viewpoint of protecting the multiple mono-coated optical fibers 11, it is preferable that the first coating portion 32 is resistant to deformation. In this embodiment, the first coating portion 32 is a metal pipe, more specifically a brass metal pipe.

[0029] The second covering portion 33 covers the first covering portion 32 and fixes the first covering portion 32. There are no particular limitations on the second covering portion 33 as long as it can fix the first covering portion 32. In this embodiment, the second covering portion 33 is a heat-shrinkable tube made of polyethylene.

[0030] (ferrule) 2B shows a longitudinal cross section of the ferrule 40. As shown in Fig. 2B, the tube 21 protruding from the end of the pipe cord 20 and the mono-coated optical fiber 11 protruding from the tube 21 are inserted into the ferrule 40. Such a ferrule 40 functions as a part of a connector for optically connecting with other components.

[0031] As shown in FIG. 2B, the ferrule 40 has a tube holding portion 41 for holding the tube 21 and a mono-coated optical fiber holding portion 42 for holding the mono-coated optical fiber 11.

[0032] The tube holding portion 41 has a tube introduction hole 41a through which the tube 21 is introduced, and a tube insertion hole 41b that is continuous with the tube introduction hole 41a and into which the tube 21 is inserted deeply. As shown in FIG. 2B, the tube introduction hole 41a and the tube insertion hole 41b are adjacently arranged in this order along the insertion direction. The inner diameter of the tube introduction hole 41a is larger than the outer diameter of the tube 21 to make it easier to introduce the tube 21, and the inner diameter decreases as the tube advances in the insertion direction. On the other hand, the tube insertion hole 41b has an inner diameter that is slightly larger than the outer diameter of the tube 21 and is substantially constant. As shown in FIG. 2B, in this embodiment, the tube 21 is inserted up to about half the length of the tube insertion hole 41b.

[0033] The mono-coated optical fiber holding part 42 has a mono-coated optical fiber introduction hole 42a into which the mono-coated optical fiber 11 is introduced, and a mono-coated optical fiber insertion hole 42b, which is adjacent to the mono-coated optical fiber introduction hole 42a and into which the mono-coated optical fiber 11 is inserted deeply. As shown in FIG. 2B , the mono-coated optical fiber introduction hole 42a and the mono-coated optical fiber insertion hole 42b are adjacently arranged in this order along the insertion direction. The inner diameter of the mono-coated optical fiber introduction hole 42a is larger than the outer diameter of the mono-coated optical fiber 11 to facilitate the introduction of the mono-coated optical fiber 11, and the inner diameter decreases as the insertion direction progresses. On the other hand, the mono-coated optical fiber insertion hole 42b has an inner diameter slightly larger than the outer diameter of the mono-coated optical fiber 11 and is substantially constant. As shown in FIG. 2B , the mono-coated optical fiber 11 is inserted over the entire length of the mono-coated optical fiber insertion hole 42b.

[0034] As described above, when the pipe cord 20 is inserted into the ferrule 40, if A / a is less than 7.84, the mono-coated optical fiber 11 can be easily inserted into the mono-coated optical fiber insertion hole 42b of the mono-coated optical fiber holding part 42. This is because, if A / a is small to a certain extent, the position of the mono-coated optical fiber 11 in the tube 21 is determined to a certain extent, and when the tube 21 is inserted into the tube insertion hole 41b, the mono-coated optical fiber 11 can be more easily aligned with the mono-coated optical fiber insertion hole 42b to a certain extent, making it easier to insert.

[0035] Furthermore, the concentricity, which represents the relationship between the configuration of the ferrule 40 and the inner diameter of the tube 21, is preferably as follows, from the viewpoint of facilitating insertion of the mono-coated optical fiber 11 into the mono-coated optical fiber insertion hole 42b. That is, the concentricity, which indicates the relationship between the entrance inner diameter of the mono-coated optical fiber introduction hole 42a and the inner diameter of the tube 21, can be calculated as follows: The entrance inner diameter of the mono-coated optical fiber introduction hole 42a is the inner diameter of the entrance where the mono-coated optical fiber 11 is first introduced, and is the part with the largest diameter. Concentricity (%) = [1 - (inner diameter of tube / inner diameter of entrance hole for single-coated optical fiber)] x 100

[0036] Here, the higher the concentricity, the easier it is to insert the mono-coated optical fiber 11 into the mono-coated optical fiber insertion hole 42b when the pipe cord 20 is inserted into the ferrule 40. From this viewpoint, the concentricity is preferably more than 36%, and more preferably 60% or more. Details will be described later with reference to examples.

[0037] There is no particular limitation on the type of ferrule 40. Examples of the ferrule 40 include a ferrule for an SC connector and a ferrule for an LC connector.

[0038] (effect) In the fan-out cord according to the present embodiment, when the cross-sectional area of ​​the inner space of the tube is A and the cross-sectional area of ​​the mono-coated optical fiber is a, A / a is greater than 1.96 and less than 7.84, which makes it easier to insert the mono-coated optical fiber into the ferrule while suppressing optical transmission loss at low temperatures. [Example]

[0039] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples.

[0040] (Fan-out cord manufacturing) Samples of fan-out cords No. 1 to 10 were manufactured. Each fan-out cord sample includes a four-fiber ribbon cord as a composite cord, a pipe cord, a connection portion, and a ferrule. First, we will explain the manufacturing of the 4-fiber ribbon cord, the manufacturing of the pipe cord, and the processing of the connection part, and finally we will explain the installation of the ferrule.

[0041] <Manufacturing of 4-fiber ribbon cord> A four-fiber ribbon was prepared, consisting of four single-coated optical fibers. The diameter of the single-coated optical fibers was 245±10 μm. The single-coated optical fibers used had two optical fiber patterns: single-mode and multimode. Kevlar (1140d x 4 strands) was attached vertically around part of the length of the prepared 4-core ribbon core wire as a tension member, and polyethylene resin was extrusion molded around the Kevlar to produce the composite cord (4-core ribbon cord) part of the fan-out cord.

[0042] <Pipe cord manufacturing> Kevlar (1140d x 4 strands) was attached longitudinally around nylon tubes (hereinafter referred to as nylon tubes) having various inner diameters shown in Table 1, and polyethylene resin was extruded around the Kevlar to house a single-core coated optical fiber, thereby producing the pipe cord portion of the fan-out cord.

[0043] Specifically, as shown in Table 1, samples No. 1 and 2 used nylon tubes with an inner diameter of 0.35 mm, samples No. 3 and 4 used nylon tubes with an inner diameter of 0.37 mm, samples No. 5 and 6 used nylon tubes with an inner diameter of 0.40 mm, samples No. 7 and 8 used nylon tubes with an inner diameter of 0.45 mm, and samples No. 9 and 10 used nylon tubes with an inner diameter of 0.70 mm.

[0044] Next, for the remaining lengthwise portion of the four-fiber ribbon that was not used as a multi-fiber cord, the resin layer between the single-coated optical fibers was torn with a sharp tool to separate the single-coated optical fibers that were connected in the width direction. As a result, most of the resin layer peeled off from the single-coated optical fiber, but the resin layer that did not peel off and remained on the surface of the single-coated optical fiber was removed by wiping with a solvent. Each of the four separated single-coated optical fibers was housed in a nylon tube with various inner diameters prepared as described above to obtain a pipe cord.

[0045] <Connection processing> Next, for Samples Nos. 2, 4, 6, 8, and 10, in order to seal the periphery of the exposed mono-coated optical fiber at the joint between the four-fiber ribbon cord and the pipe cord with a sealant, the sealing portion was passed through a mold, and a two-component mixed adhesive was filled and cured. Next, a brass metal pipe was placed so as to cover the cured adhesive, and the periphery of the metal pipe was covered with a polyethylene heat-shrinkable tube, which was then shrunk. On the other hand, in Samples Nos. 1, 3, 5, 7, and 9, the single-coated optical fiber exposed at the splice was left exposed without being sealed, and was covered with a metal pipe and a heat-shrinkable tube.

[0046] <Ferrule installation> At the end of the pipe cord, a nylon tube was exposed so as to protrude, and a mono-coated optical fiber was exposed so as to protrude from the protruding nylon tube. After injecting thermosetting resin into the ferrule, the protruding nylon tube was inserted into the tube insertion hole of the tube holding portion of the ferrule. At the same time, an attempt was made to insert the protruding mono-coated optical fiber into the mono-coated optical fiber insertion hole of the mono-coated optical fiber holding portion of the ferrule. After insertion, the thermosetting resin was cured, and the end face of the ferrule was polished. The ferrule used had a tube insertion hole with an entrance inner diameter of 1.0 mm.

[0047] (evaluation) The fabricated fan-out cords were evaluated for processability and fluctuation in optical transmission loss. The workability was evaluated by whether or not the mono-coated optical fiber could be properly inserted into the mono-coated optical fiber insertion hole when the nylon tube was inserted into the tube insertion hole of the ferrule as described above. If the insertion was possible, it was rated as "good," and if it was not possible, it was rated as "poor." The evaluation results are shown in Table 1. The optical transmission loss fluctuation was evaluated by measuring the fluctuation in optical transmission loss during a heat cycle test. Here, the optical transmission loss fluctuation indicates the degree to which the optical transmission loss fluctuated during the heat cycle test, with the optical transmission loss measured at 20°C as the reference.

[0048] Specifically, in accordance with JIS C61300-2-22, a heat cycle of holding each temperature for one hour in the range of -20°C to 60°C was repeated 12 times, and the fluctuation from the reference light transmission loss was evaluated. When the mono-coated optical fiber was single mode, light with a wavelength of 1550 nm was transmitted, and when it was multimode, light with a wavelength of 1300 nm was transmitted.

[0049] The smaller the optical transmission loss fluctuation, the better, but a transmission loss fluctuation of 0.2 dB or less is preferable as the standard for use in high-temperature and low-temperature environments. Therefore, a maximum optical transmission loss fluctuation of 0.2 dB or less was rated as "good," and a value exceeding 0.2 dB was rated as "poor." The evaluation results are shown in Table 1. Note that for each sample, the maximum optical transmission loss fluctuation was observed at -20°C. Samples that achieved a "good" rating in all of the above evaluations of processability, single-mode optical transmission loss fluctuation, and multimode optical transmission loss fluctuation were deemed to have passed. The evaluation results are shown in Table 1. Table 1 also shows the A / a and concentricity of each sample.

[0050] [Table 1]

[0051] As can be seen from Table 1, when A / a exceeds 1.96, the fluctuation in optical transmission loss is suppressed to 0.2 dB or less, satisfying the standard. On the other hand, when A / a becomes too large, exceeding 7.84, the processability becomes poor. This is thought to be because an A / a ratio of more than 1.96 prevents contact between the mono-coated optical fiber and the tube even if the tube shrinks at low temperatures.On the other hand, if A / a is 7.84 or more, the inner diameter of the nylon tube is too large, making it difficult to determine the position of the mono-coated optical fiber inside the nylon tube, and making it difficult to insert the mono-coated optical fiber into the mono-coated optical fiber insertion hole of the ferrule when attaching it. This shows that A / a is preferably greater than 1.96 and less than 7.84.

[0052] Furthermore, as can be seen from Table 1, when the concentricity was 36% or less, the workability was poor.

[0053] Furthermore, as can be seen from a comparison of samples No. 1 and 2, No. 3 and 4, No. 5 and 6, No. 7 and 8, and No. 9 and 10, when the single-coated optical fiber was sealed with a sealant at the splice, the fluctuation in optical transmission loss was further suppressed. This is thought to be because sealing the single-coated optical fiber with a sealant at the splice suppresses the occurrence of microbends in the single-coated optical fiber at the splice. Note that Table 1 shows the results when a two-component adhesive was used as the sealant, but similar results were obtained when EVA was used as the sealant. [Industrial Applicability]

[0054] The fan-out cord of the present invention is useful, for example, for efficient transmission of light at low temperatures. [Explanation of symbols]

[0055] 1 Fanout Code 10 multi-core cord 11 Single-coated optical fiber 11a Resin layer 12, 22 Reinforcement 13, 23 outer covering 20 Pipe Code 21 tubes 30 Connection 31 Encapsulating material 32 First coating section 33 Second coating section 40 ferrules 41 Tube holding part 41a Tube introduction hole 41b Tube insertion hole 42 Single-coated optical fiber holder 42a Single-coated optical fiber introduction hole 42b Single-coated optical fiber insertion hole

Claims

1. a multi-core cord including a portion of each of a plurality of mono-coated optical fibers; a plurality of pipe cords each including another portion of one of the plurality of mono-coated optical fibers; a connection portion disposed between the multi-core cord and the plurality of pipe cords; and the pipe cord includes a tube that accommodates the mono-coated optical fiber, When the cross-sectional area of ​​the inner space of the tube is A and the cross-sectional area of ​​the mono-coated optical fiber is a, A / a is greater than 1.96 and less than 7.

84. Fanout code.

2. 2. The fan-out cord according to claim 1, wherein the plurality of mono-coated optical fibers are sealed with a sealing material at the connection portion.

3. 2. The fan-out cord of claim 1, wherein the tube comprises nylon 12.

4. A pipe code used in the fan-out code according to any one of claims 1 to 3.

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