Optical fiber ribbon and method for manufacturing optical fiber ribbon

Abstract

This optical fiber ribbon (10) comprises: a plurality of single-core coated optical fibers disposed in parallel and coated with resin; and a plurality of coupling portions (30) disposed between adjacent single-core coated optical fibers (20) and partially coupling the adjacent single-core coated optical fibers. In a cross section orthogonal to the longitudinal direction of the single-core coated optical fiber in a region where no coupling portion is disposed, the ratio of the longest length (D2) to the shortest length (D1) in the cross section of the single-core coated optical fiber is in the range of 1.02-1.14.

Description

Optical fiber ribbon and method for manufacturing the same

[0001] The present invention relates to an optical fiber ribbon and a method for manufacturing the optical fiber ribbon.

[0002] In recent years, data traffic has increased dramatically due to the spread of IoT (Internet of Things), the full-scale commercialization of 5G, and autonomous driving of automobiles, and demand is growing for the development and construction of high-speed, large-capacity optical fiber communication networks to support this. To economically realize the development and construction of high-speed, large-capacity optical fiber communication networks, it is important to accommodate as many mono-coated optical fibers (optical fibers) as possible in existing ducts. When accommodating many mono-coated optical fibers in an existing duct, a rollable ribbon in which mono-coated optical fibers are intermittently connected is used from the viewpoint of workability in wiring installation work (see, for example, Patent Document 1).

[0003] Patent Document 1 describes an optical fiber ribbon having a plurality of optical fibers arranged in parallel and an inter-fiber connecting portion that intermittently connects adjacent optical fibers. The method for manufacturing an optical fiber ribbon described in Patent Document 1 involves first arranging a plurality of optical fibers in a row with a predetermined gap between them. Next, a tape-forming resin is applied so as to cover the entire periphery of the plurality of optical fibers, and then the tape-forming resin between adjacent optical fibers before the tape-forming resin hardens is partially removed. Finally, the tape-forming resin is hardened to produce the optical fiber ribbon. The optical fiber ribbon in the manufactured optical fiber ribbon is covered with a substantially uniform and thick tape-forming resin.

[0004] JP 2012-108331 A

[0005] However, the optical fiber ribbon described in Patent Document 1 contains a large amount of tape-forming resin, which makes it difficult to remove the resin during use.

[0006] An object of the present invention is to provide an optical fiber ribbon with high resin removability and a method for manufacturing the optical fiber ribbon.

[0007] In order to solve the above problems, according to one aspect of the present invention, there is provided an optical fiber ribbon comprising: a plurality of mono-coated optical fibers coated with resin, arranged in parallel; and a plurality of connecting portions arranged between adjacent mono-coated optical fibers, which partially connect the adjacent mono-coated optical fibers; wherein in a cross section perpendicular to the longitudinal direction of the mono-coated optical fibers in an area where no connecting portions are arranged, the ratio of the maximum length to the minimum length in the cross section of the mono-coated optical fibers is within a range of 1.02 to 1.14.

[0008] According to another aspect of the present invention, there is provided a method for manufacturing an optical fiber ribbon, comprising the steps of: arranging a plurality of single-coated optical fibers in parallel; applying an uncured photocurable resin in a tape shape to the plurality of single-coated optical fibers to form an uncured tape layer; rotating a rotary blade or inserting and removing a needle with respect to the uncured tape layer to form a plurality of connection portions that partially connect adjacent single-coated optical fibers and separation portions that separate adjacent single-coated optical fibers; and irradiating light to harden the uncured tape layer, wherein in the step of forming the connection portions and separation portions, the distance between the rotary blade or needle and the single-coated optical fibers is within a range of 0 to 10 μm.

[0009] According to the present invention, an optical fiber ribbon with high resin removability and a method for manufacturing the optical fiber ribbon can be provided.

[0010] 1A to 1C are diagrams showing an optical fiber ribbon according to a preferred embodiment of the present invention. FIG. 2 is a schematic diagram illustrating the shortest and longest lengths in the cross section of an optical fiber. FIG. 3 is a flowchart of a method for manufacturing an optical fiber ribbon. FIG. 4 is a diagram showing the schematic configuration of an optical fiber ribbon manufacturing apparatus. FIGS. 5A to 5C are side views showing the schematic configuration of a rotary blade of a separating die. FIG. 6 is a side view showing the schematic rotation of the rotary blade. FIG. 7 is a diagram for explaining the process of forming a connecting portion and a separating portion. FIG. 8 is a diagram showing the schematic configuration of an optical fiber ribbon manufacturing apparatus according to a modified example.

[0011] Hereinafter, an optical fiber ribbon and a method for manufacturing an optical fiber ribbon according to a preferred embodiment of the present invention will be described. In this specification, when a numerical range is indicated by "to", the lower limit and upper limit are included in the numerical range.

[0012] (1) Configuration of the Optical Fiber Ribbon Figure 1A is a schematic plan view of the optical fiber ribbon 10, Figure 1B is a cross-sectional view taken along line A-A in Figure 1A, and Figure 1C is a cross-sectional view taken along line B-B in Figure 1A. Figure 2 is a schematic view for explaining the minimum length D1 and maximum length D2 in the cross section of the optical fiber 20.

[0013] The optical fiber ribbon 10 has a plurality of mono-coated optical fibers (hereinafter also simply referred to as "optical fibers") 20 and a plurality of connecting portions 30. The optical fiber ribbon 10 may have a plurality of spaced portions 41. As shown in FIGS. 1A to 1C , the optical fiber ribbon 10 of this embodiment has a plurality of mono-coated optical fibers 20, a plurality of connecting portions 30, and a plurality of spaced portions 41.

[0014] The optical fibers 20 are arranged in parallel. The number of optical fibers 20 is not particularly limited as long as it is two or more. The number of optical fibers 20 included in one optical fiber ribbon 10 is selected appropriately depending on the application of the optical fiber ribbon 10. The number of optical fibers 20 included in one optical fiber ribbon 10 is approximately 2 to 12. In this embodiment, one optical fiber ribbon 10 has 12 optical fibers 20 arranged in parallel.

[0015] 1B and 1C , the optical fiber 20 includes an optical fiber strand 21, a primary coating layer 22, and a secondary coating layer 23. The optical fiber strand 21, the primary coating layer 22, and the secondary coating layer 23 may be the same as the optical fiber strand, first coating layer, and second coating layer of a known optical fiber. A colored layer may be further formed on the secondary coating layer 23 of the optical fiber 20. Preferably, the colors of the colored layers of the multiple optical fibers 20 within a single optical fiber ribbon 10 are different from each other within the optical fiber ribbon 10. This allows the multiple optical fibers 20 to be distinguished from one another within a single optical fiber ribbon 10.

[0016] In this embodiment, a tape layer 40 is further disposed around the plurality of optical fibers 20, and adjacent optical fibers 20 are intermittently connected by the tape layer 40. In this embodiment, the region where adjacent optical fibers 20 are partially connected is a connection portion 30, and the region where adjacent optical fibers 20 are partially separated is a separation portion 41.

[0017] The connecting portions 30 are disposed between all adjacent optical fibers 20, partially connecting the adjacent optical fibers 20. The separating portions 41 are disposed between all adjacent optical fibers 20, partially separating the adjacent optical fibers 20. The arrangement of the connecting portions 30 and the separating portions 41 is not particularly limited. In the optical fiber ribbon 10 of this embodiment, the connecting portions 30 and the separating portions 41 are alternately disposed in the longitudinal direction of the optical fiber ribbon 10. Furthermore, in the optical fiber ribbon 10, it is preferable that two or more separating portions 41 are disposed between adjacent connecting portions 30 in the lateral direction of the optical fiber ribbon 10 (the arrangement direction of the optical fibers 20). In the optical fiber ribbon 10 of this embodiment, two separating portions 41 are disposed between adjacent connecting portions 30 in the lateral direction of the optical fiber ribbon 10 (the arrangement direction of the optical fibers 20). This allows the number of connecting portions 30 to be reduced, thereby shortening the overall width of the optical fiber ribbon 10. The optical fiber ribbon 10 satisfies the IEC standard (IEC 60794-1-31:2018, JIS C 6838:2020) and the Telcordia standard (Telcordia GR-20). In addition, in the short direction of the optical fiber ribbon 10, the spaced portions 41 are preferably arranged so that adjacent spaced portions 41 partially overlap each other.

[0018] 1A and 1B , the length L1 of the connecting portion 30 when the optical fiber ribbon 10 is viewed in plan is not particularly limited, but is, for example, in the range of 5 mm to 15 mm. The thickness T of the connecting portion 30 is also not particularly limited, but is, for example, in the range of 0.26 mm to 0.29 mm. When the length L1 and thickness T of the connecting portion 30 are within these ranges, the strength of the connecting portion 30 is increased, and the connecting portion 30 is less likely to tear even when the optical fiber ribbon 10 is wound along the longitudinal direction or twisted as needed. Meanwhile, the length L2 of the separating portion 41 when the optical fiber ribbon 10 is viewed in plan is not particularly limited, but is, for example, in the range of 45 mm to 55 mm. When the length L2 of the separating portion 41 is within this range, the optical fiber ribbon 10 can be easily wound or twisted along the longitudinal direction when housed in a cable. In this embodiment, the length L1 and thickness T of the connecting portion 30 and the length L2 of the spaced portion 41 are each the average values ​​measured at any five locations within the optical fiber ribbon 10.

[0019] As shown in FIGS. 1C and 2 , in a cross section perpendicular to the longitudinal direction of the optical fiber 20 in a region where the coupling portion 30 is not disposed, the ratio (D2 / D1) of the longest length D2 to the shortest length D1 in the cross section is within a range of 1.02 to 1.14, and more preferably within a range of 1.07 to 1.14. In this embodiment, the shape of the cross section is not substantially circular but is substantially rectangular. The shortest length D1 in the cross section refers to the length of the shortest line segment among the line segments connecting any two points on the outer edge of the cross section and the center of gravity G of the cross section. In this embodiment, the shortest length D1 in the cross section is preferably the length in the direction along the arrangement direction of the multiple optical fibers 20. Furthermore, the longest length D2 in the cross section refers to the length of the longest line segment among the line segments connecting any two points on the outer edge of the cross section. In this embodiment, the line segment corresponding to the longest length D2 is inclined at approximately 45° with respect to the line segment corresponding to the shortest length D1. The line segment corresponding to the longest length D2 may or may not pass through the center of gravity in the cross section. In this embodiment, the line segment corresponding to the longest length D2 passes through the center of gravity G.

[0020] (2) Manufacturing Method of Optical Fiber Ribbon Next, a manufacturing method of the optical fiber ribbon 10 will be described. FIG. 3 is a flowchart of the optical fiber ribbon 10. FIG. 4 is a perspective view of a manufacturing apparatus 100 for manufacturing the optical fiber ribbon 10. FIGS. 5A to 5C are side views showing the schematic configuration of the rotary blade of the separating die. FIG. 6 is a side view showing the schematic rotation of the rotary blade. FIG. 7 is a diagram for explaining the process of forming the connecting portion 30 and the separating portion 41.

[0021] As shown in FIG. 3, the manufacturing method of the optical fiber ribbon 10 of this embodiment includes a step of arranging optical fibers in parallel (S110), a step of forming an uncured tape layer (S120), a step of forming a connecting portion 30 and a separating portion 41 (S130), and a step of curing the uncured tape layer (S140).

[0022] In the step (S110) of arranging the optical fibers in parallel, the above-described optical fibers 20 are arranged in parallel. The optical fibers 20 may be commercially available products or may be manufactured.

[0023] In the step (S120) of forming an uncured tape layer, for example, a manufacturing apparatus 100 shown in Fig. 4 is used to form the uncured tape layer 40. Specifically, while the optical fibers 20 are transported in the transport direction A, an uncured photocurable resin is applied in a tape form to the optical fibers 20 using a tape die 50, thereby forming the tape layer 40.

[0024] In the step (S130) of forming the connecting portion 30 and the separating portion 41, the connecting portion 30 and the separating portion 41 are formed using, for example, a manufacturing apparatus 100 shown in FIG. 4 . Specifically, the rotary blades 62, 64, and 66 of the separating die 60 are rotated relative to the tape layer 40 to remove a portion of the tape layer 40, thereby forming the connecting portion 30 and the separating portion 41. In the separating die 60, multiple rotary blades 62, 64, and 66 are installed facing the exit surface of the optical fiber 20. The rotation of each rotary blade 62, 64, and 66 is controlled by a motor, and the rotary blades 62, 64, and 66 rotate in accordance with the transport of the optical fiber 20, with their respective rotation axes coinciding. As shown in FIG. 5A , a notch 64 a is formed in the central rotary blade 64, and as shown in FIG. 5B , notches 62 a and 66 a are also formed in the rotary blades 62 and 66 on both sides. As shown in Fig. 5C, the notch 64a of the central rotary blade 64 is out of phase with the notches 62a, 66a of the side rotary blades 62, 66. In the step (S130) of forming the connecting portion 30 and the separating portion 41, as shown in Fig. 6, when the rotary blades 62, 64, 66 rotate following the transport of the optical fiber 20, the rotary blades 62, 64, 66 rotate while the notch 64a of the central rotary blade 64 is out of phase with the notches 62a, 66a of the side rotary blades 62, 66, and the separating portions 4 and the connecting portions 3 are alternately formed. Note that, for ease of explanation, three rotary blades 62, 64, 66 are depicted in Figs. 4 to 6, but eleven such rotary blades are required to manufacture the optical fiber ribbon 10 shown in Fig. 1.

[0025] As shown in Figure 7, the distance D between the rotary blades 62, 64, 66 and the optical fiber 20 is preferably in the range of 0 to 10 µm, more preferably 0 to 5 µm. By shortening the distance between the rotary blades 62, 64, 66 and the optical fiber 20 in this way, the tape layer 40 formed on the side of the optical fiber 20 can be made thinner. This improves resin removal, as described below, and satisfies the IEC standard and the Telcordia standard. At this time, excess photocurable resin is sucked and collected by the resin suction device 70.

[0026] In the step (S140) of curing the uncured tape layer, the tape layer 40 is irradiated with light by the light irradiation device 80 to semi-cure the uncured tape layer, and finally, the semi-cured tape layer is completely cured by further irradiating with light by the light irradiation device 90. The integrated irradiation doses of the upstream first light irradiation device 80 and the downstream second light irradiation device 90 are adjusted so that the integrated irradiation dose of the first light irradiation device 80 is small and the integrated irradiation dose of the second light irradiation device 90 is large. Because the distance D between the rotary blades 62, 64, 66 of the separating die 60 and the optical fiber 20 is within the range of 0 to 10 μm, the amount of photocurable resin applied to the optical fiber 20 is small, and the uncured photocurable resin does not wrap around the optical fiber 20 during the period from the step (S130) of forming the connecting portion 30 and the separating portion 41 to the time the uncured photocurable resin is cured. As a result, in a cross section perpendicular to the longitudinal direction of the optical fiber 20 in a region where the coupling portion 30 is not disposed, the ratio of the maximum length to the minimum length in the cross section falls within the range of 1.02 to 1.14.

[0027] 8 may be used instead of the separating die 60 shown in Fig. 4 in the step (S130) of forming the connecting portion 30 and the separating portion 41, and needles 132, 134, 136 of the separating die 130 may be inserted into and removed from the tape layer 40 while controlling their elevation to remove part of the tape layer 40, thereby forming the connecting portion 30 and the separating portion 41. In such a case, too, the distance D between the needles 132, 134, 136 and the optical fiber 20 is preferably in the range of 0 to 10 µm, and more preferably 0 to 5 µm.

[0028] (Effects) As described above, according to the present invention, the ratio of the maximum length to the minimum length in the cross section of the optical fiber 20 is within a predetermined range, so that the tape layer 40 in the short direction of the optical fiber 20 is thin in the region where the connecting portion 30 is not disposed. This improves resin removability and makes it possible to obtain an optical fiber ribbon 10 that meets the width-related items of various international standards.

[0029] The present invention will be described in more detail below with reference to examples. However, the scope of the present invention is not limited by these examples, and the embodiments can be modified without departing from the spirit of the present invention.

[0030] (1) Sample Preparation A 250 μm outer diameter mono-coated optical fiber was prepared by applying a primary coating of a urethane acrylate photo-curable resin and a secondary coating of a urethane acrylate photo-curable resin to a 125 μm outer diameter silica glass SM optical fiber (the process of arranging optical fibers in parallel). Then, using the manufacturing apparatus shown in FIG. 4, 12 mono-coated optical fibers were aligned and coated with a urethane acrylate photo-curable resin to form a tape layer (the process of forming an uncured tape layer). Then, a rotary blade was rotated to form a connecting portion and a separating portion (the process of forming a connecting portion and a separating portion). The connecting portion was designed to have a length of 10 mm, and the separating portion was designed to have a length of 50 mm. The distance between the rotary blade and the mono-coated optical fiber in the process of forming the connecting portion and the separating portion was set as shown in Table 1. The uncured photo-curable resin was then cured using an upstream light irradiation device and a downstream light irradiation device to obtain an optical fiber ribbon (the process of curing the uncured photo-curable resin).

[0031] (2) Evaluation of Samples (2.1) Appearance Evaluation of Tape Structure For each sample, a ruler was used to measure whether the connection portions and gaps between optical fibers were manufactured according to the design values. The measurement results are shown in Table 1. In Table 1, the criteria for ◯, △, and × are as follows: ◯: Conforms to the design values ​​(error within 10%) △: There is an error of more than 10% from the design values ​​×: No gaps are formed

[0032] (2.2) Evaluation of resin removal ability Bristle hardness specified in JIS S 3061:1995 is 60 N / cm ２Using the brush described below, optical fibers were separated from the optical fiber ribbon at room temperature (23°C). The separated optical fibers were then wiped with a commercially available resin removal tool (pulled while rubbing in one direction from the back to the front). This determined the number of wiping strokes required to remove the tape layer from the surface of the optical fiber. This test was performed 32 times (n=32) for each sample, and the average number of wiping strokes was calculated. The resin removability was evaluated based on the calculation results using the following criteria: ◯: Number of wiping strokes was less than 5 △: Number of wiping strokes was 5 to less than 10 ×: Number of wiping strokes was 10 or more

[0033] (2.3) Evaluation of Standards Compliance Each sample was examined to see whether it conformed to the IEC standard (IEC 60794-1-31:2018) and the Telcordia standard (Telcordia GR-20). Specifically, for the IEC standard, it was examined whether the width of the optical fiber ribbon was 3.4 mm or less, and for the Telcordia standard, it was examined whether the width of the optical fiber ribbon was 3.27 mm or less, and the conformance to the standards was evaluated according to the following criteria: ○: Conforms to the standard ×: Does not conform to the standard

[0034] Table 1 shows the optical fiber ribbon number, the distance between the rotary blade and the single-coated optical fiber, the ratio of the maximum length to the minimum length in the cross section perpendicular to the longitudinal direction of the optical fiber, and each evaluation result.

[0035]

[0036] As shown in Table 1, in Example Samples 1 to 3, in which the ratio of the longest length to the shortest length in the cross section perpendicular to the longitudinal direction of the optical fiber was within the range of 1.02 to 1.14, the tape structure, resin removability, and conformance to standards were all good. This is thought to be due to the presence of thin portions of the tape layer coating the optical fiber. In particular, Example Samples 1 and 2, in which the ratio was within the range of 1.07 to 1.14, showed even better resin removability.

[0037] On the other hand, in Comparative Example 4, where the ratio was not within the predetermined range, conformance to the standard was poor. This is thought to be due to the thick film thickness of the tape layer coating the optical fiber. In Comparative Examples 5 and 6, the distance between the rotary blade and the mono-coated optical fiber was excessively large (large clearance), and excess photocurable resin was integrated across the optical fibers (not separated), preventing the desired connection and separation portions from being formed.

[0038] The optical fiber ribbon according to the present invention is useful, for example, as an optical fiber used in a high-speed, large-capacity optical fiber communication network.

[0039] REFERENCE SIGNS LIST 10 Optical fiber ribbon 20 Single-coated optical fiber 21 Optical fiber strand 22 Primary coating layer 23 Secondary coating layer 30 Connection portion 40 Tape layer 41 Separation portion 50 Tape die 60, 130 Separation die 62, 64, 66 Rotary blade 70 Resin suction device 80 First light irradiation device 90 Second light irradiation device 100 Manufacturing device 132, 134, 136 Needle

Claims

1. An optical fiber ribbon comprising: a plurality of resin-coated mono-coated optical fibers arranged in parallel; and a plurality of connecting portions arranged between adjacent mono-coated optical fibers to partially connect the adjacent mono-coated optical fibers; wherein in a cross section perpendicular to the longitudinal direction of the mono-coated optical fibers in an area where no connecting portions are arranged, the ratio of the maximum length to the minimum length in the cross section of the mono-coated optical fibers is within the range of 1.02 to 1.

14.

2. An optical fiber ribbon according to claim 1, wherein the ratio of the maximum length to the minimum length in the cross section is within the range of 1.07 to 1.

14.

3. An optical fiber ribbon according to claim 1, wherein the shortest length in the cross section is the length in the direction along the arrangement direction of the plurality of mono-coated optical fibers.

4. An optical fiber ribbon core wire as defined in claim 1, further comprising spacing sections disposed between adjacent mono-coated optical fibers to separate the adjacent mono-coated optical fibers, the number of the plurality of mono-coated optical fibers being 12, and the plurality of connecting sections being disposed in the arrangement direction of the plurality of mono-coated optical fibers such that two or more of the spacing sections are located between adjacent connecting sections.

5. A method for manufacturing an optical fiber ribbon, comprising: a step of arranging a plurality of single-coated optical fibers in parallel; a step of applying an uncured photocurable resin in the form of a tape to the plurality of single-coated optical fibers to form an uncured tape layer; a step of rotating a rotary blade or inserting and removing a needle with respect to the uncured tape layer to form a plurality of connection sections where adjacent single-coated optical fibers are partially connected and spaced sections where adjacent single-coated optical fibers are spaced apart; and a step of irradiating light to harden the uncured tape layer, wherein in the step of forming the connection sections and the spaced sections, the distance between the rotary blade or needle and the single-coated optical fibers is within a range of 0 to 10 μm.

6. A method for manufacturing an optical fiber ribbon according to claim 5, wherein in the step of forming the connecting portion and the separating portion, the distance between the rotary blade or needle and the single-coated optical fiber is set within the range of 0 to 5 μm.

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