Intermittently connected optical fiber ribbon and optical fiber cable

Abstract

The purpose of the present disclosure is to provide an intermittently connected optical fiber ribbon and an optical fiber cable in which an optical fiber ribbon can be easily made round around the axis of the longitudinal direction thereof. An intermittently connected optical fiber ribbon (1A) comprises a plurality of coated optical fibers (10) arranged in parallel, and connection parts (20) that intermittently connect portions between adjacent coated optical fibers (10) in the longitudinal direction. In a cross-sectional view of the intermittently connected optical fiber ribbon (1A), each connection part (20) has a first part (21) and a second part (22) divided by a center line (C1) connecting the centers of the adjacent coated optical fibers (10), the first part (21) occupies 70% or more of the area of the entire connection part (20), and a surface (22A) of the second part (22) connecting the adjacent coated optical fibers (10) is recessed toward the center line (C1).

Description

Intermittently Connected Optical Fiber Ribbon and Optical Fiber Cable

[0001] The present disclosure relates to an intermittently connected optical fiber ribbon and an optical fiber cable. This application claims priority based on Japanese Patent Application No. 2024-226603 filed on December 23, 2024, and incorporates all the descriptions described in the above Japanese application.

[0002] Patent Document 1 and Patent Document 2 disclose an intermittently connected optical fiber ribbon having a plurality of optical fiber cores arranged in parallel and a connecting portion that intermittently connects at least a part between adjacent optical fiber cores in the longitudinal direction.

[0003] International Publication No. 2017 / 145955 International Publication No. 2022 / 059654

[0004] The intermittently connected optical fiber ribbon of the present disclosure is an intermittently connected optical fiber ribbon having a plurality of optical fiber cores arranged in parallel and a connecting portion that intermittently connects a part between adjacent optical fiber cores in the longitudinal direction. In a cross-sectional view of the intermittently connected optical fiber ribbon, the connecting portion has a first portion and a second portion separated by a center line connecting the centers of adjacent optical fiber cores. The first portion occupies an area of 70% or more of the entire connecting portion, and the surface connecting adjacent optical fiber cores of the second portion is concave toward the center line between the optical fiber cores.

[0005] FIG. 1 is a plan view of an optical fiber ribbon according to the present embodiment. FIG. 2 is a cross-sectional view illustrating a configuration as viewed from the arrow direction of a cross-section taken along line II-II in FIG. 1. FIG. 3 is a cross-sectional view of an optical fiber cable in which an optical fiber ribbon is accommodated. FIG. 4 is a schematic view showing a manufacturing apparatus for an optical fiber ribbon according to the present embodiment. FIG. 5 is a cross-sectional view of an optical fiber ribbon according to a modified example of the present embodiment.

[0006] When intermittently coupled optical fiber ribbons are mounted on an optical fiber cable, the ribbons are rolled around an axis with the longitudinal direction as the axis and housed within the optical fiber cable. To accommodate optical fiber ribbons at high density within the optical fiber cable, intermittently coupled optical fiber ribbons that are easier to roll are desired.

[0007] The purpose of this disclosure is to provide an intermittently connected optical fiber ribbon and optical fiber cable that are easy to roll up around an axis with the longitudinal direction as the axis.

[0008] According to this disclosure, it is possible to provide an intermittently connected optical fiber ribbon and optical fiber cable that can be easily rolled up around an axis with the longitudinal direction as the axis.

[0009] First, embodiments of the present disclosure will be listed and described. (1) An intermittently connected optical fiber ribbon according to an embodiment of the present disclosure is an intermittently connected optical fiber ribbon having a plurality of optical fiber cores arranged in parallel and a connecting portion that intermittently connects a portion of the adjacent optical fiber cores in the longitudinal direction, wherein in a cross-sectional view of the intermittently connected optical fiber ribbon, the connecting portion has a first part and a second part divided by a center line connecting the centers of adjacent optical fiber cores, the first part occupies 70% or more of the area of ​​the entire connecting portion, and the surface of the second part that connects adjacent optical fiber cores is concave toward the center line between the optical fiber cores.

[0010] With this configuration, the connecting portion is positioned off-center relative to the center line connecting the centers of adjacent optical fiber cores. This makes it easier to roll the optical fiber ribbon by aligning the second portion of the connecting portion with the inside of the bend when rolling it around the axis with the longitudinal direction as the axis. Furthermore, since the surface of the second portion of the connecting portion is concave toward the center line, it is even easier to roll the optical fiber ribbon. As a result, the ability to store the optical fiber ribbon within the optical fiber cable is improved, and the optical fiber ribbon can be housed at a high density within the optical fiber cable.

[0011] (2) In the intermittently connected optical fiber ribbon described in (1) above, in a cross-sectional view of the intermittently connected optical fiber ribbon, the surface connecting adjacent optical fiber cores in the first part may be recessed toward the center line between the optical fiber cores.

[0012] With this configuration, the thickness of the connecting portion in the recessed area is reduced, making it easier to further coil the optical fiber ribbon around its longitudinal axis. It also makes it easier to remove the resin from the connecting portion with a brush when separating the optical fiber cores into single cores. Furthermore, by reducing the cross-sectional area of ​​the connecting portion, the cross-sectional area of ​​the optical fiber ribbon can be reduced, allowing for a higher density of optical fiber ribbon to be housed within the optical fiber cable.

[0013] (3) In the intermittently connected optical fiber ribbon described in (1) or (2) above, the connecting portion is formed from a part of the coating resin covering the outer circumference of the optical fiber core, and in a cross-sectional view of the intermittently connected optical fiber ribbon, the difference between the thickness of the coating resin of the first optical fiber core and the thickness of the coating resin of the second optical fiber core among the adjacent optical fiber cores connected by the connecting portion may be 10 μm or less.

[0014] With this configuration, the difference in thickness of the coating resin between adjacent optical fiber cores is small, which reduces the likelihood of wire wobble occurring while the optical fiber ribbon is running.

[0015] (4) In any of the intermittently connected optical fiber ribbons described in (1) to (3) above, adjacent optical fiber cores may be connected by the connecting portion while remaining separated from each other.

[0016] With this configuration, a connecting portion of a desired shape can be easily formed. For example, a connecting portion of a desired shape can be formed by utilizing the weight of the resin coated between the optical fiber cores.

[0017] (5) The optical fiber cable according to the embodiment of the present disclosure has an intermittently connected optical fiber ribbon as described in (1) to (4) above, and the core density obtained by dividing the total number of optical fiber cores constituting the intermittently connected optical fiber ribbon by the cross-sectional area of ​​the optical fiber cable is 5.0 cores / mm２ That's fine too.

[0018] With this configuration, a high-density optical fiber cable can be obtained by using the intermittently connected optical fiber ribbon described above.

[0019] Specific examples of the optical fiber cables of this disclosure will be described below with reference to the drawings. However, the present invention is not limited to these examples and is intended to include all modifications within the meaning and scope of the claims as indicated by the claims.

[0020] (Optical Fiber Ribbon) Figure 1 is a plan view of the optical fiber ribbon 1A according to this embodiment. Figure 1 shows the unconnected portion spread out in the parallel direction. Figure 2 is a cross-sectional view illustrating the configuration of the cross section along line II-II in Figure 1, viewed from the direction of the arrow.

[0021] As shown in Figures 1 and 2, the optical fiber ribbon 1A comprises a plurality of optical fiber cores 10 and a plurality of connecting parts 20. In this example, the optical fiber ribbon 1A comprises eight optical fiber cores 10A to 10H. The eight optical fiber cores 10A to 10H are arranged in a direction intersecting the longitudinal direction of the optical fiber cores. The optical fiber cores 10A to 10H are connected by the connecting parts 20, with adjacent optical fiber cores 10 separated from each other.

[0022] As shown in Figure 2, the optical fiber core 10 has a glass fiber 11 and two coating layers 12 and 13. The glass fiber 11 consists of a core and a cladding. The two coating layers 12 and 13 cover the periphery of the glass fiber 11.

[0023] The resin constituting the inner coating layer 12 that comes into contact with the glass fiber 11 is, for example, a soft resin with a relatively low Young's modulus used as a buffer layer. The resin constituting the outer coating layer 13 is, for example, a hard resin with a relatively high Young's modulus used as a protective layer.

[0024] Although the optical fiber core 10 has two coating layers 12 and 13, it may also have only one coating layer. Furthermore, the optical fiber core 10 may have a colored layer on its outermost surface.

[0025] The connecting section 20 intermittently connects a portion of adjacent optical fiber cores 10 in the longitudinal direction. That is, as shown in Figure 1, connecting sections 20, where adjacent optical fiber cores 10 are connected, and unconnected sections 30, where adjacent optical fiber cores 10 are not connected, are intermittently provided in the longitudinal and widthwise directions of the parallel optical fiber cores 10A to 10H. In this example, connecting sections 20 and unconnected sections 30 are intermittently provided between all optical fiber cores 10. In other words, the optical fiber ribbon 1A is an optical fiber ribbon in which each core is intermittently connected. Note that the connecting sections 20 and unconnected sections 30 may be provided between some optical fiber cores. For example, the optical fiber ribbon 1A may be formed as an optical fiber ribbon in which every two cores are intermittently connected.

[0026] The connecting portion 20 is made of a resin material such as an acrylic UV-curable resin or an epoxy UV-curable resin. As the resin constituting the connecting portion 20, for example, a low-friction, soft resin with added lubricant is used.

[0027] In this example, the connecting portion 20 is formed from a part of the coating resin 40 that covers the outer circumference of the optical fiber core 10. The coating resin 40 is the resin that forms the outermost layer of the optical fiber ribbon 1A.

[0028] As shown in Figure 2, in a cross-sectional view of the optical fiber ribbon 1A, the connecting portion 20 is positioned off-center with respect to the center line C1 connecting the centers of the parallel optical fiber cores 10A to 10H. Specifically, the connecting portion 20 has a first portion 21 and a second portion 22 separated by the center line C1. In other words, the first portion 21 is the part located below the parallel plane of the connecting portion 20 in the cross-sectional view of Figure 2, and the second portion 22 is the part located above the parallel plane of the connecting portion 20. The parallel plane is a plane passing through the center line C1. The first portion 21 occupies more than 70% of the total area of ​​the connecting portion 20.

[0029] Furthermore, in a cross-sectional view of the optical fiber ribbon 1A, the surface 22A of the second part 22 of the connecting portion 20 that connects adjacent optical fiber cores is concave toward the center line C1.

[0030] With this configuration, the connecting portion 20 is positioned off-center with respect to the center line C1 connecting the centers of adjacent optical fiber cores 10. Therefore, when rolling the optical fiber ribbon 1A around its longitudinal axis, the second portion 22 of the connecting portion 20 is positioned on the inside of the bend, making it easier to roll the optical fiber ribbon. Furthermore, since the surface 22A of the second portion 22 of the connecting portion 20 is concave toward the center line C1, it is even easier to roll the optical fiber ribbon 1A. As a result, the ability to store the optical fiber ribbon 1A inside the optical fiber cable is improved, and the optical fiber ribbon 1A can be stored at a high density inside the optical fiber cable.

[0031] In this embodiment, in a cross-sectional view of the optical fiber ribbon 1A, the surface 21A of the first part 21 of the connecting portion 20 that connects adjacent optical fiber cores 10 is recessed toward the center line C1.

[0032] As a result, the thickness of the recessed connecting portion 20 is reduced, making it easier to further coil the optical fiber ribbon 1A around its axis with the longitudinal direction as the axis, and also making it easier to remove the resin from the connecting portion 20 with a brush or the like when separating the optical fiber cores 10 into single cores. Furthermore, since the cross-sectional area of ​​the connecting portion 20 is reduced, the cross-sectional area of ​​the optical fiber ribbon 1A can be reduced, allowing the optical fiber ribbon 1A to be housed in the optical fiber cable at an even higher density.

[0033] (Optical Fiber Cable) Figure 3 is a cross-sectional view of an optical fiber cable 50 in which an optical fiber ribbon 1A is housed. The optical fiber cable 50 is a slotless type cable. The optical fiber cable 50 comprises a cable core 60 and a cable sheath 70 provided around the cable core.

[0034] The cable core 60 is, for example, round. The cable core 60 includes a plurality of optical fiber ribbons 1A and a retaining tape 61. The bundle of the plurality of optical fiber ribbons 1A is bundled together in a round shape by being wrapped vertically or horizontally with the retaining tape 61.

[0035] The outside of the securing tape 61 is covered with a cable sheath 70. The cable sheath 70 is made of, for example, polyethylene resin, flame-retardant polyethylene resin, or polyvinyl chloride resin. A tensile strength member 71 and a tear cord 72 are embedded in the cable sheath 70. The tensile strength member 71 and the tear cord 72 are embedded longitudinally during the extrusion molding of the cable sheath 70.

[0036] The tensile strength member 71 is used to maintain longitudinal strength. The tensile strength member 71 is formed from, for example, fiber-reinforced plastic (FRP). Examples of fiber-reinforced plastics include aramid FRP, glass FRP, and carbon FRP.

[0037] The tearing cord 72 is used to tear the cable sheath 70 in the longitudinal direction of the cable. The tearing cord 72 is a cord-like member with a circular cross-section, for example, made of a resin material such as nylon or polyester.

[0038] The fiber optic cable 50 has a core density of 5.0 cores / mm², which is calculated by dividing the total number of fiber optic cores 10 constituting the fiber optic ribbon 1A by the cross-sectional area of ​​the fiber optic cable 50. ２ The configuration is as described above. In this way, a high-density optical fiber cable 50 can be obtained by using the optical fiber ribbon 1A.

[0039] The optical fiber cable in which the optical fiber ribbon 1A is housed is not limited to the structure of the optical fiber cable 50 shown in Figure 3. For example, the optical fiber ribbon 1A can also be a slot type having slot rods.

[0040] (Method for Manufacturing Optical Fiber Ribbons) Next, a method for manufacturing optical fiber ribbon 1A will be described using Figure 4. Figure 4 is a schematic diagram showing the manufacturing apparatus 80 for optical fiber ribbon 1A according to this embodiment.

[0041] The manufacturing apparatus 80 includes a supply unit 81, a resin coating apparatus 82, a resin curing apparatus 83, and a winding unit 84.

[0042] The supply unit 81 has a plurality of supply bobbins that supply a plurality of optical fiber cores 10A to 10H included in the optical fiber ribbon 1A. Each supply bobbin is wound with optical fiber cores 10A to 10H that are formed in advance by a wire drawing apparatus (not shown). The optical fiber cores 10A to 10H fed out from each supply bobbin are conveyed to the resin coating apparatus 82.

[0043] The resin coating apparatus 82 is configured to apply an ultraviolet-curable resin for the coating resin 40 including the connecting portion 20 to the optical fiber cores 10A to 10H arranged in parallel. In this example, in the resin coating apparatus 82, with the plurality of optical fiber cores 10A to 10H arranged in parallel and separated from each other, the ultraviolet-curable resin for the coating resin 40 is applied around the plurality of optical fiber cores 10A to 10H. Note that the ultraviolet-curable resin is not applied at the position corresponding to the non-connecting portion 30. For example, a member for blocking the ultraviolet-curable resin is arranged at the position corresponding to the non-connecting portion 30 at the resin supply port of the resin coating apparatus 82. The plurality of optical fiber cores 10A to 10H coated with the ultraviolet-curable resin for the coating resin 40 are conveyed to the resin curing apparatus 83.

[0044] The resin curing apparatus 83 is configured to cure the ultraviolet-curable resin for the coating resin 40 applied to the plurality of optical fiber cores 10A to 10H by irradiating ultraviolet rays. The optical fiber ribbon 1A with the ultraviolet-curable resin for the coating resin 40 cured is wound up by the winding unit 84.

[0045] In such a method for manufacturing the optical fiber ribbon 1A, the connecting portion 20 is formed, for example, by utilizing the self-weight of the resin constituting the connecting portion 20. Specifically, in the resin curing device 83, the timing of resin curing is adjusted so that the resin applied between adjacent optical fiber cores 10 is cured in a state where it hangs downward due to its self-weight. As a result, a first portion 21 that occupies more than 70% of the entire connecting portion 20 is formed below the center line C1, and a second portion 22 having a downwardly concave surface 22A is formed above the center line.

[0046] As the resin of the connecting portion 20, a resin having a Young's modulus of, for example, 240 MPa or less at room temperature (for example, 23°C) is used. Such a resin is likely to hang downward due to its self-weight before curing and is likely to be rounded after curing. Thereby, it is easy to form the connecting portion 20 biased downward, and the resin of the connecting portion 20 is less likely to break when the optical fiber ribbon 1A is rounded.

[0047] The recess in the surface 21A of the first portion 21 of the connecting portion 20 is formed, for example, using a guide or the like.

[0048] Note that since the connecting portion 20 of the optical fiber ribbon 1A is formed by the coating resin 40 that covers the outer periphery of the optical fiber core 10, when the connecting portion 20 is formed by the self-weight of the resin, portions other than the connecting portion 20, particularly the coating resin 40 that covers the upper part of the optical fiber core 10, are likely to be deformed. If the thickness of the coating resin 40 is non-uniform, line breakage is likely to occur during running.

[0049] Therefore, it is preferable that the optical fiber ribbon 1A is formed such that the difference in the thickness of the coating resin 40 that covers the outer periphery of the optical fiber core 10 is not so large in adjacent optical fiber cores connected by the connecting portion 20.

[0050] For example, the optical fiber ribbon 1A may be formed such that, in a cross-sectional view of the optical fiber ribbon 1A, the difference between the thickness D1 of the coating resin 40 covering the outer circumference of the first optical fiber core (for example, optical fiber core 10A in Figure 2) and the thickness D2 of the coating resin 40 covering the outer circumference of the second optical fiber core (for example, optical fiber core 10B in Figure 2) is 10 μm or less.

[0051] For example, the optical fiber ribbon 1A manufacturing apparatus 80 may be configured to reduce the difference in thickness of the coating resin 40 covering adjacent optical fiber cores 10 by pressing the resin that will form the upper surface of the optical fiber ribbon 1A covering the upper part of the optical fiber core 10 against the surface of a guide just before the coating resin 40 hardens with the resin that will form the connecting portion 20 hanging down due to its own weight. This makes it possible to reduce the difference in thickness of the coating resin 40 covering adjacent optical fiber cores 10 while forming a connecting portion 20 in which the surface 22A of the second portion 22 is recessed toward the center line C1.

[0052] By reducing the difference in thickness of the coating resin 40 between adjacent optical fiber cores 10 in this way, wire wobble is less likely to occur during operation.

[0053] In the manufacturing apparatus 80 shown in Figure 4, the connecting portion 20 is formed while the optical fiber cores 10A to 10H are conveyed horizontally. However, the apparatus may be configured to form the connecting portion 20 while the fibers are conveyed vertically. For example, in the resin coating apparatus 82, the connecting portion 20 may be formed into a desired shape by using a guide corresponding to the shape of the connecting portion 20, or by adjusting the shape of the die hole, for example.

[0054] (Modified Optical Fiber Ribbon) Figure 5 is a cross-sectional view of an optical fiber ribbon 1B according to a modified example of this embodiment. In this embodiment, components similar to those in the first embodiment are denoted by the same reference numerals and described accordingly, and parts that would otherwise be redundant are omitted as appropriate.

[0055] As shown in Figure 5, the optical fiber ribbon 1B comprises multiple optical fiber cores 10 and multiple connecting parts 20.

[0056] The optical fiber cores 10A to 10H are connected by a connecting portion 20, with adjacent optical fiber cores separated from each other. In this modified example, the connecting portion 20 is formed only in the portion that connects adjacent optical fiber cores 10.

[0057] In a cross-sectional view of the optical fiber ribbon 1B, the connecting portion 20 is positioned off-center with respect to the center line C1 connecting the centers of the parallel optical fiber cores 10A to 10H. Specifically, the connecting portion 20 has a first portion 21 and a second portion 22 separated by the center line C1. The first portion 21 occupies more than 70% of the total area of ​​the connecting portion 20. In this example, the first portion 21 is the part below the center line C1, and the second portion 22 is the part above the center line C1.

[0058] Furthermore, in a cross-sectional view of the optical fiber ribbon 1B, the surface 22A of the second part 22 of the connecting portion 20 that connects adjacent optical fiber cores is concave toward the center line C1. Also, in a cross-sectional view of the optical fiber ribbon 1B, the surface 21A of the first part 21 of the connecting portion 20 that connects adjacent optical fiber cores 10 is concave toward the center line C1.

[0059] The optical fiber ribbon 1B configured in this way can also obtain the same effects as the optical fiber ribbon 1A in the above embodiment.

[0060] Although the present disclosure has been described above based on specific embodiments, the present invention is not limited to these examples and is intended to be expressed by the claims, with all modifications within the meaning and scope of the claims being equivalent.

[0061] It should be understood that at least one configuration or feature described in each embodiment and example can be combined with other embodiments and examples, or modified in various ways.

[0062] Optical fiber ribbons 1A and 1B have eight optical fiber cores 10A to 10H. However, optical fiber ribbons 1A and 1B may have a number of optical fiber cores that is a multiple of four, such as 12 or 24.

[0063] The optical fiber ribbons 1A and 1B may be configured such that adjacent optical fiber cores 10 are in contact with each other. Such optical fiber ribbons 1A and 1B, in which adjacent optical fiber cores 10 are in contact with each other, can be formed, for example, by reducing the distance between the optical fiber cores 10 so that they are in contact with each other, while the resin applied between adjacent optical fiber cores 10 is hanging down due to its own weight and before the resin has completely hardened.

[0064] 1A, 1B Optical fiber ribbon 10, 10A to 10H Optical fiber core 11 Glass fiber 12 Coating layer 13 Coating layer 20 Connecting section 21 Part 1 21A Surface connecting adjacent optical fiber cores 22 Part 22A Surface connecting adjacent optical fiber cores 30 Unconnected section 40 Coating resin 50 Optical fiber cable 60 Cable core 61 Retaining tape 70 Cable sheath 71 Tensile strength material 72 Tear string 80 Manufacturing equipment 81 Supply section 82 Resin coating equipment 83 Resin curing equipment 84 Winding section C1 Centerline

Claims

1. An intermittently connected optical fiber ribbon having a plurality of optical fiber cores arranged in parallel and a connecting portion that intermittently connects a portion of the adjacent optical fiber cores in the longitudinal direction, wherein, in a cross-sectional view of the intermittently connected optical fiber ribbon, the connecting portion has a first part and a second part divided by a center line connecting the centers of adjacent optical fiber cores, the first part occupies 70% or more of the area of ​​the entire connecting portion, and the surface of the second part that connects adjacent optical fiber cores is concave toward the center line between the optical fiber cores.

2. The intermittently connected optical fiber ribbon according to claim 1, wherein, in a cross-sectional view of the intermittently connected optical fiber ribbon, the surface connecting adjacent optical fiber cores in the part is recessed toward the center line between the optical fiber cores.

3. The connecting portion is formed from a part of the coating resin covering the outer circumference of the optical fiber core, and in a cross-sectional view of the intermittently connected optical fiber ribbon, the difference between the thickness of the coating resin of the first optical fiber core and the thickness of the coating resin of the second optical fiber core among the adjacent optical fiber cores connected by the connecting portion is 10 μm or less, as described in claim 1 or claim 2.

4. The intermittently connected optical fiber ribbon according to any one of claims 1 to 3, wherein adjacent optical fiber cores are connected by the connecting portion while separated from each other.

5. Having an intermittently connected optical fiber ribbon as described in any one of claims 1 to 4, wherein the core density obtained by dividing the total number of optical fiber cores constituting the intermittently connected optical fiber ribbon by the cross-sectional area of ​​the optical fiber cable is 5.0 cores / mm². ２ That concludes the explanation of fiber optic cables.

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