Fiber optic cable

Abstract

An optical fiber cable (1) which comprises: a cable main body part (2) that comprises 3,000 or more optical fiber core wires (20) and a cladding material (3) that contains the optical fiber core wires (20); and a multi-core connector (5) that is connected to ends of the optical fiber core wires (20). With respect to this optical fiber cable (1), the cladding material (3) contains 0.2% by mass to 1.5% by mass of silicone.

Description

Technical Field

[0001] This disclosure relates to an optical fiber cable. This application claims priority based on Japanese Application No. 2021-086748 filed on May 24, 2021, and incorporates by reference all the descriptions recited in the Japanese application.

Background Art

[0002] Patent Document 1 discloses a multi-core optical fiber cable in which a plurality of optical fiber ribbon cores are integrally assembled at high density.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

[0004] An optical fiber cable according to one aspect of this disclosure includes a cable main body portion including 3,000 or more optical fiber cores and an outer covering material that houses the optical fiber cores, a multi-core connector connected to an end portion of the optical fiber core, and a flexible tube provided at at least one end portion of the cable main body portion, and the multi-core connector is housed in the flexible tube, the outer diameter of the flexible tube and the outer diameter of the cable main body portion are 60 mm or less, the allowable bending radius of the flexible tube is 220 mm, the outer covering material contains silicone with a mass percentage of 0.2% or more and 1.5% or less fruit, The bending rigidity of the aforementioned optical fiber cable is 25 N·mm , , , , , ,

[0003] , , , , , , , The bending rigidity of the aforementioned optical fiber cable is 25 N·mm , fruit, , , , , ,

[0005] , , , 2 , <00​​​​​​​ [Figure 1] Figure 1 is a diagram illustrating an optical fiber cable according to one aspect of this embodiment. [Figure 2] Figure 2 is a cross-sectional view taken along the line A-A in Figure 1. [Figure 3] Figure 3 is a plan view showing an intermittently connected optical fiber ribbon in the longitudinal direction. [Figure 4] Figure 4 illustrates how an optical fiber cable according to one aspect of this embodiment is laid. [Figure 5] Figure 5 illustrates an example of a device used to calculate the static friction coefficient of an optical fiber cable according to one aspect of this embodiment. [Figure 6] Figure 6 shows the tensile tension as a function of the towing length. [Figure 7] Figure 7 is a cross-sectional view of another optical fiber cable according to one aspect of this embodiment. [Modes for carrying out the invention]

[0006] [Issues this disclosure aims to address] Optical fiber cables used for outdoor wiring are often fusion-spliced ​​within junction boxes such as closures during the wiring process, and are also fusion-spliced ​​or connected via connectors at the point of entry into the central office. Therefore, for example, with ultra-high-density optical fiber cables (3000 cores or more), fusion splicing can take a considerable amount of time. Furthermore, when ultra-high-density optical fiber cables are laid in ducts using a traction method, a high occupancy rate of the optical fiber cable within the duct can increase the tensile force, potentially reducing the ease of cable installation. For these reasons, there is a need for optical fiber cables that can improve the work efficiency during installation.

[0007] This disclosure aims to provide an optical fiber cable that can improve work efficiency during the installation of optical fiber cables.

[0008] [Description of Embodiments in this Disclosure] First, the embodiments of this disclosure will be listed and described. An optical fiber cable according to one aspect of the present disclosure includes (1) a cable body portion including 3,000 or more optical fiber cores and an outer covering material that houses the optical fiber cores, a multi-core connector connected to an end of the optical fiber core, and a flexible tube provided at at least one end of the cable body portion. The multi-core connector is housed in the flexible tube. The outer diameter of the flexible tube and the outer diameter of the cable body portion are 60 mm or less. The allowable bending radius of the flexible tube is 220 mm. The outer covering material contains silicone with a mass percentage of 0.2% or more and 1.5% or less. fruit, The bending rigidity of the aforementioned optical fiber cable is 25 N·mm 2 The following conditions apply: The variation in the bending stiffness of the optical fiber cable in the circumferential direction is within 5% of the average value of the bending stiffness. According to this configuration, since a multi-core connector is provided at the end of the optical fiber core, the time required for fusion connection can be shortened or eliminated. In addition, the outer covering material of the optical fiber cable according to the above configuration contains silicone with a mass percentage of 0.2% or more and 1.5% or less. Therefore, when the optical fiber cable is laid in a duct by a pulling method, the friction coefficient between the optical fiber cable and the duct can be reduced. Therefore, the optical fiber cable according to the above configuration has good line passing performance. Thus, according to the above configuration, the working efficiency during the laying of the optical fiber cable can be improved. According to this configuration, since the multi-core connector is housed in the flexible tube, it is possible to prevent the connector from being damaged or coming apart during pulling without the multi-core connector being exposed. According to this configuration, while reducing the outer diameters of the flexible tube and the cable body portion, the optical fiber cable can be made multi-core and high-density. Optical fiber cables with this configuration are easy to bend and can be bent to a certain extent in any direction, so they are easy to run, for example, through a duct that has multiple curved sections.

[0009] Further, in an optical fiber cable according to one aspect of the present disclosure, (2) It is preferable that the static friction coefficient between the outer covering material and the stainless steel flat plate is 0.20 or more and 0.46 or less. According to this configuration, since the static friction coefficient between the outer covering material and the stainless steel flat plate is 0.20 or more and 0.46 or less, the wire passing property of the optical fiber cable is good.

[0010] Further, in the optical fiber cable according to one aspect of the present disclosure, (3) It is preferable that the cross-section of the outer covering material is polygonal. According to this configuration, since the cross-section of the outer covering material is polygonal, in the cross-section of the optical fiber cable, when the optical fiber cable is passed through the duct, the portion where the duct and the optical fiber cable contact is a point contact. Therefore, according to the optical fiber cable according to the above configuration, the frictional resistance during duct passage can be reduced, and thus the wire passing property during the laying of the optical fiber cable is good.

[0012] Further, the optical fiber cable according to one aspect of the present disclosure is (5) The optical fiber core wires are arranged in parallel, and in part or all of the optical fiber core wires, a connecting portion where adjacent optical fiber core wires are connected and a non-connecting portion where adjacent optical fiber core wires are not connected are intermittently provided in the longitudinal direction to form an intermittently connected type optical fiber ribbon. According to this configuration, since the optical fiber core wires form an intermittently connected type optical fiber ribbon, they are easy to bundle and form a sub-unit. Therefore, a relatively large number of optical fiber core wires can be accommodated at a high density in the cable.

[0013] Further, in the optical fiber cable according to one aspect of the present disclosure, (6) A pitch conversion portion is further provided between the first end of the optical fiber ribbon and the multi-core connector to convert the pitch of the optical fiber core wires. The pitch of the optical fiber core wires in the multi-core connector is longer than the pitch of the optical fiber core wires in the optical fiber ribbon. The outer diameter of the optical fiber core wire is 160 μm or more and 185 μm or less. The core density of the cable body is 10 cores / mm². 2 It is preferable if the above conditions are met. With this configuration, even in high-density optical fiber cables using small-diameter fibers, the fusion splicing time can be shortened by pre-converting the pitch of the optical fiber cores using a pitch conversion unit and connecting them to a multi-core connector. Therefore, the optical fiber cable according to the above configuration can improve work efficiency during the installation of optical fiber cables.

[0016] Furthermore, in an optical fiber cable according to one aspect of this disclosure, (9) The glass diameter of the optical fiber core is preferably 80 μm or more and 120 μm or less. This configuration makes it possible to suppress a decrease in the thickness of the optical fiber core's coating, thereby suppressing a decrease in the mechanical strength of the optical fiber cable.

[0017] [Effects of this disclosure] According to this disclosure, it is possible to provide an optical fiber cable that can improve work efficiency during the installation of optical fiber cables.

[0018] (Details of the embodiments of this disclosure) Specific examples of optical fiber cables according to embodiments of this disclosure are described below with reference to the drawings. However, this disclosure is not limited to these examples and is intended to include all changes within the meaning and scope of the claims, as indicated by the claims.

[0019] (First Embodiment) The optical fiber cable 1 according to this embodiment will be described with reference to Figures 1 and 2. For the sake of clarity, the terms "front-back direction," "left-right direction," and "up-down direction" will be used as appropriate in this description. These directions are relative directions defined for the optical fiber cable 1 illustrated in Figures 1 and 2. Here, the "up-down direction" includes the "up" and "down" directions with respect to Figure 2, with the cable center as the origin. The "front-back direction" includes the "up" and "down" directions with respect to Figure 1 (the "forward" and "backward" directions with respect to Figure 2). The "left-right direction" includes the "left" and "right" directions with respect to Figures 1 and 2, with respect to the cable center as the origin. Figure 1 is an illustration of the optical fiber cable 1. Figure 2 is a cross-sectional view taken along line A-A in Figure 1.

[0020] As illustrated in Figure 1, the optical fiber cable 1 includes a cable body 2, a plurality of multi-core connectors 5, a flexible tube 6, a pulling eye 7, and a pitch conversion unit 8. As illustrated in Figure 2, the cable body 2 includes a slot rod 52, a plurality of subunits 4, and an outer sheath material 3.

[0021] The slot rod 52 has a tension member 54 in the center, and multiple ribs are arranged radially in cross-section around it to form multiple slot grooves. The slot grooves are formed in a unidirectional spiral or SZ shape along the longitudinal direction of the cable body 2. One or more subunits 4 are housed in each of the multiple slot grooves.

[0022] Subunit 4 has multiple intermittently connected optical fiber ribbons 40. The optical fiber ribbon 40 contains, for example, 12 optical fiber cores 20. The outer diameter of each optical fiber core 20 is, for example, 200 μm. Subunit 4 is formed by bundling optical fiber ribbons 40 containing optical fiber cores 20. Specifically, subunit 4 is formed by rolling and twisting the optical fiber ribbons 40. Note that the subunits 4 may be twisted together within the slot grooves. The optical fiber core 20 has a glass fiber made of, for example, quartz glass, and a coating layer formed around it. The glass fiber has a core portion and a cladding portion. The core portion is located at the radial center of the optical fiber core 20. The cladding portion is arranged to cover the periphery of the core portion.

[0023] Here, the optical fiber ribbon 40 will be described in detail with reference to Figure 3. As illustrated in Figure 3, the optical fiber ribbon 40 is an intermittently connected type optical fiber ribbon in which multiple optical fiber cores 20A to 20L are arranged in parallel in a direction perpendicular to the longitudinal direction, and in some or all of the multiple optical fiber cores 20A to 20L, there are connecting sections 41 where adjacent optical fiber cores are connected and unconnected sections 42 where adjacent optical fiber cores are not connected, provided intermittently in the longitudinal direction. The outer diameter of each optical fiber core 20A to 20L is 220 μm or less, for example, 180 μm or 200 μm.

[0024] In the optical fiber ribbon 40 according to this embodiment, twelve optical fiber cores 20A to 20L are arranged in parallel. The locations where connecting portions 41 and disconnecting portions 42 are intermittently provided may be between some optical fiber cores (intermittently every two cores) or between all optical fiber cores (intermittently every one core). In the optical fiber ribbon 40 illustrated in Figure 3, the connections are intermittently every two cores, and no disconnecting portions 42 are provided between the optical fiber cores 20A and 20B, 20C and 20D, 20E and 20F, 20G and 20H, 20I and 20J, and 20K and 20L.

[0025] The connecting portion 41 in the optical fiber ribbon 40 is formed by applying a connecting resin 43, such as an ultraviolet-curing resin or a thermosetting resin, between the optical fiber cores. By applying the connecting resin 43 between predetermined optical fiber cores, connecting portions 41 and unconnected portions 42 are intermittently provided, and each optical fiber core 20A to 20L is integrated in a parallel state. The connecting resin 43 may be applied to only one side of the parallel surface formed by the parallel optical fiber cores 20A to 20L, or it may be applied to both sides. Alternatively, the optical fiber ribbon 40 may be manufactured by applying tape resin to one or both sides of the parallel optical fiber cores 20A to 20L to connect all the optical fiber cores 20A to 20L, and then cutting a portion of it with a rotary blade or the like to form the unconnected portion 42.

[0026] As illustrated in Figure 2, a retaining tape 55 is wrapped around the slot rod 52. The retaining tape 55 may be made of polyethylene terephthalate (PET) formed into a tape shape, or a material made by laminating a base material such as PET with a nonwoven fabric. An absorbent agent (e.g., absorbent powder) may be applied to the inside of the retaining tape 55.

[0027] The outer covering material 3 is formed by extruding an insulating resin around the retaining tape 55. Since the outer covering material 3 is formed along the outer circumferential shape of the slot rod 52 and the retaining tape 55, the cross-section of the outer covering material 3 is polygonal. The outer covering material 3 is formed from a resin composition in which silicone is compounded with a resin such as low-density polyethylene. In this embodiment, the outer covering material 3 contains silicone at a mass percentage of 0.2% to 1.5%. The outer covering material 3 may also contain inorganic fillers such as magnesium hydroxide or talc from the viewpoint of suppressing low-temperature shrinkage of the outer covering material 3.

[0028] The outer diameter of the cable body 2, i.e., the outer diameter of the sheath 3, is, for example, 28 mm. The cable body 2 contains 3000 or more (for example, 3456) optical fiber cores 20. Therefore, the optical fiber cable 1 is an ultra-high-core cable. The density of the optical fiber cores 20 in the optical fiber cable 1 is 5.6 cores / mm². 2 Therefore, if the outer diameter of each optical fiber core 20 in the optical fiber ribbon 40 is 200 μm, the core density of the optical fiber cable 1 is 5 cores / mm². 2 It can be done to the extent of above.

[0029] As illustrated in Figure 1, the multi-core connector 5 is, for example, a 12-core MPO connector with an MT connector as its base structure. In this embodiment, the optical fiber cable 1 has, for example, 288 multi-core connectors 5. These multi-core connectors 5 are housed in a flexible tube 6. Note that in Figure 1, only three multi-core connectors 5 are shown for illustrative purposes. The multi-core connectors 5 are attached to the ends of the optical fiber ribbon 40. In other words, the multi-core connectors 5 are connected to the ends of the optical fiber cores 20.

[0030] The flexible tube 6 is a bellows-shaped cylindrical tube and is flexible. The flexible tube 6 is provided at the end of the optical fiber cable 1. The surface of the flexible tube 6 is covered with polyvinyl chloride or the like. The outer diameter of the flexible tube 6 is 60 mm or less, and in this embodiment it is 60 mm. The outer diameter of the flexible tube 6 is larger than the outer diameter of the cable body 2 and the outer diameter of the cylindrical part 72 of the pulling eye 7, which will be described later. The allowable bending radius of the flexible tube 6 is, for example, 220 mm. However, the allowable bending radius of the flexible tube 6 is not limited to this. The flexible tube 6 houses the end of the cable body 2 and the end of the pulling eye 7.

[0031] The pulling eye 7 is made of a material with sufficient strength to pull the optical fiber cable 1. Such a material may be a metal such as iron. The pulling eye 7 comprises an annular portion 71 and a cylindrical portion 72. The annular portion 71 is ring-shaped. The installer can pull the optical fiber cable 1 by, for example, connecting a wire to the annular portion 71 and pulling the wire with a winch. The cylindrical portion 72 is substantially cylindrical. The first end of the cylindrical portion 72 is connected to the annular portion 71, and the second end of the cylindrical portion 72 is connected to the end of the cable body portion 2. A part of the cylindrical portion 72 is housed in a flexible tube 6.

[0032] The pitch conversion unit 8 is provided between the first end 400 of the optical fiber ribbon 40 and the end of the multi-core connector 5. The pitch conversion unit 8 is configured to convert the pitch of the optical fiber cores 20 to the array pitch of the multi-core connector 5. In this embodiment, the pitch of the optical fiber cores 20 in the optical fiber ribbon 40 is 200 μm, and the array pitch in the multi-core connector 5 is 250 μm. The pitch conversion unit 8 converts the pitch of the optical fiber cores 20 from 200 μm to 250 μm by separating the multiple optical fiber cores 20 into single cores and widening the pitch. As a result, multiple optical fiber cores 20 are connected to the multi-core connector 5 at a pitch of 250 μm.

[0033] (Method for laying fiber optic cable 1) Next, with reference to Figure 4, a method for laying the optical fiber cable 1 according to this embodiment will be described. In this specification, an example will be used in which the optical fiber cable 1 is routed through a duct 10 placed in a manhole located underground. The duct 10 is made of, for example, stainless steel. The duct 10 is, for example, substantially cylindrical. The duct 10 has a plurality of curved sections. However, the duct 10 may be straight. The duct 10 is fixed to a wall or bottom surface.

[0034] The installer threads the wire from the outlet 10b of the duct 10 towards the inlet 10a. The installer connects the wire coming out of the inlet 10a to the annular portion 71 of the pulling eye 7 and pulls the wire from the outlet 10b of the duct 10 using a winch. As a result, the optical fiber cable 1 is inserted into the duct 10. When the optical fiber cable 1 passes through the duct 10, because the cross-section of the outer sheath material 3 is polygonal, the contact portion 3a (see Figure 2) where the duct 10 and the optical fiber cable 1 meet becomes a point contact in the cross-section of the optical fiber cable 1.

[0035] The installer uses a winch to pull the wire connected to the annular section 71 until the annular section 71 emerges from the outlet 10b of the duct 10. Once the annular section 71 emerges from the outlet 10b, the installer disconnects the wire from the annular section 71. After that, the installer removes the flexible tube 6 and the pulling eye 7 from the optical fiber cable 1 and connects the multi-core connector 5 to other optical fiber cables or optical communication equipment. In other words, the multi-core connector 5 allows for easy connection work without having to fusion splice the optical fiber cores 20 contained in the optical fiber cable 1 to other optical fiber cores.

[0036] (Measurement of static friction coefficient of optical fiber cable 1) The inventor conducted an experiment using the apparatus 100 illustrated in Figure 5 to calculate the static friction coefficient of the optical fiber cable 1. As illustrated in Figure 5, the apparatus 100 comprises a first metal plate 101, a second metal plate 102, and four cylindrical members 103. The four cylindrical members 103 are inserted through holes provided at the four corners of the first metal plate 101 and the second metal plate 102, respectively. In Figure 5, for illustrative purposes, only two of the cylindrical members 103 are shown. The first metal plate 101 and the second metal plate 102 are made of stainless steel to simulate the wall surface of the duct 10.

[0037] The inventor calculated the static friction coefficient of the optical fiber cable 1 by sandwiching the optical fiber cable 1 between a first metal plate 101 and a second metal plate 102 positioned above the first metal plate 101, applying a load to the second metal plate 102, and then pulling the optical fiber cable 1 in the longitudinal direction of the metal plates (to the right in Figure 5). The load applied to the second metal plate 102 is 0.5 kg. The longitudinal lengths of the first metal plate 101 and the second metal plate 102 are approximately 150 mm. The tensile speed applied to the optical fiber cable 1 is approximately 500 mm / min. In this embodiment, the static friction coefficient was evaluated using the average value of the tensile tension.

[0038] The results of the above experiment showed that the static friction coefficient of optical fiber cables with sheaths that did not contain silicone was 0.54 on average. In contrast, the static friction coefficient of optical fiber cables 1 with sheaths 3 containing 0.2% by mass silicone was 0.46, the static friction coefficient of optical fiber cables 1 with sheaths 3 containing 0.3% by mass silicone was 0.36, the static friction coefficient of optical fiber cables 1 with sheaths 3 containing 0.5% by mass silicone was 0.30, and the static friction coefficient of optical fiber cables 1 with sheaths 3 containing 1.5% by mass silicone was 0.20. Furthermore, when the concentration of silicone added to sheath 3 was less than 0.2% by mass, the static friction coefficient was approximately the same as that of optical fiber cables with sheaths that did not contain silicone. Conversely, when the concentration of silicone added to the outer sheath material 3 is 1.5% or more by mass, the rate of decrease in the static friction coefficient of the optical fiber cable 1 slows down, and it was confirmed that the effect is not sufficient to justify the cost. From these results, the inventors confirmed that the concentration of silicone added to the outer sheath material 3 of the optical fiber cable 1 is preferably 0.2% to 1.5% by mass.

[0039] (Measurement of tensile tension when laying optical fiber cable 1) Figure 6 shows the tensile tension as a function of the traction length. In Figure 6, the intersection of the line X extending in the vertical direction (up and down) and each line graph represents the tensile tension when the tip of the optical fiber cable 1 reaches point X in Figure 4. The intersection of the line Y and each line graph represents the tensile tension when the tip of the optical fiber cable 1 reaches point Y in Figure 4. The intersection of the line Z and each line graph represents the tensile tension when the tip of the optical fiber cable 1 reaches point Z in Figure 4.

[0040] The inventor measured the tensile tension when laying each optical fiber cable by running an optical fiber cable having an outer sheath material without silicone additive and an optical fiber cable 1 having an outer sheath material 3 with silicone additive at a mass percentage of 0.3% through the duct 10 illustrated in Figure 4.

[0041] As a result of the above experiment, the inventor confirmed that the tensile force required to thread the optical fiber cable 1 having an outer sheath 3 with 0.3% silicone by mass through the duct 10 is approximately half the tensile force required to thread the optical fiber cable having an outer sheath without silicone through the duct 10. The inventor also confirmed that when the optical fiber cable 1 having an outer sheath 3 with 0.3% silicone by mass is threaded through the duct 10, there is almost no damage to the optical fiber cable 1 due to friction between the optical fiber cable 1 and the duct 10.

[0042] (Measurement of bending stiffness of optical fiber cable 1) If the bending stiffness of the optical fiber cable 1 is too high, it becomes difficult to handle, and if it fluctuates by more than 5% of the average value of the bending stiffness in the circumferential direction, the ease of bending becomes directional, making it difficult to thread. Thus, since bending stiffness is a parameter that affects the ease of threading the optical fiber cable 1, the inventor also calculated the bending stiffness of the optical fiber cable 1 using a double-ended support tensioning method. The bending stiffness of the optical fiber cable 1 was calculated based on the repulsive force of the optical fiber cable 1 when the length of the optical fiber cable 1 is 700 mm, the distance between the jigs is 500 mm, the pressing speed is 200 mm / min, and the indenter displacement is 10 mm.

[0043] As a result, the inventor determined that the bending rigidity of optical fiber cable 1 is 15 N·mm 2 More than 25N mm 2 The inventors confirmed the following: In addition, they confirmed that the bending directionality is small in the optical fiber cable 1 because the tension member 54 is located in the center. Specifically, by changing the measurement position in the longitudinal direction and changing the bending direction, they measured the average value and variation of the bending stiffness and confirmed that the value of the variation in bending stiffness was within 5% of the average value of the bending stiffness.

[0044] In the optical fiber cable 1 described above, a multi-core connector 5 is connected to the end of the optical fiber core 20. Therefore, even if the cable body 2 is an ultra-multi-core cable that requires a considerable amount of time for fusion splicing, the time required for fusion splicing can be reduced. In addition, since the outer sheath material 3 contains silicone at a mass percentage of 0.2% to 1.5%, when the optical fiber cable 1 is laid inside the duct 10 by traction, the static friction coefficient between the optical fiber cable 1 and the duct 10 can be reduced. As a result, the optical fiber cable 1 has good ductability, which can improve work efficiency when laying the optical fiber cable 1.

[0045] Furthermore, with the optical fiber cable 1 described above, the static friction coefficient between the outer sheath material 3 containing silicone with a mass percentage of 0.2% to 1.5% and the first and second stainless steel metal plates 101 and 102 is 0.20 to 0.46. Since the static friction coefficient between the outer sheath material without silicone and the first and second metal plates 101 and 102 is an average of 0.54, the optical fiber cable 1 with the outer sheath material 3 has better wire-passability within the duct 10.

[0046] Furthermore, with the optical fiber cable 1 described above, the cross-section of the outer sheath material 3 is polygonal, and the portion where the duct 10 and the optical fiber cable 1 meet (contact portion 3a) is a point contact in the cross-section of the optical fiber cable 1. Therefore, compared to the case where the portion where the duct 10 and the optical fiber cable 1 meet is a surface contact in the cross-section of the optical fiber cable 1, the friction generated between the duct 10 and the optical fiber cable 1 is reduced. As a result, the ease with which the optical fiber cable 1 can be routed within the duct 10 is good.

[0047] (Second embodiment) Next, with reference to Figure 7, the optical fiber cable 1A according to this embodiment will be described. In the description of this embodiment, parts that overlap with the description of the first embodiment will be denoted by the same reference numerals, and their descriptions will be omitted as appropriate. As illustrated in Figure 7, the optical fiber cable 1A differs from the optical fiber cable 1 in that it has a slotless structure without slot rods and has a larger number of cores.

[0048] The optical fiber cable 1A includes 48 subunits 4A. Each subunit 4A contains 288 optical fiber cores 20. Therefore, the optical fiber cable 1A contains 13,824 optical fiber cores 20. The outer diameter of the cable body 2 of the optical fiber cable 1A is 35.5 mm. In this embodiment, the outer diameter of the optical fiber cores 20 is between 160 μm and 185 μm, and the density of the optical fiber cores 20 in the optical fiber cable 1A is 10 cores / mm². 2That concludes the explanation. Therefore, it is higher than the density of optical fiber cores 20 in optical fiber cable 1.

[0049] Thus, the optical fiber cable 1A can accommodate the optical fiber cores 20 at high density without making the cable body 2 excessively large, so it can be routed through the duct 10. In addition, in this embodiment as well, the fusion splicing time can be shortened by changing the pitch of the optical fiber cores 20 from 200 μm to 250 μm in order to ensure compatibility with the multi-core connector 5.

[0050] Although this disclosure has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of this disclosure. Furthermore, the number, position, shape, etc. of the components described above are not limited to the embodiments described above and can be changed to a number, position, shape, etc. that is suitable for carrying out this disclosure.

[0051] In the first embodiment, the cross-section of the outer covering material 3 is polygonal, but it may also be circular, for example.

[0052] In the above embodiment, the optical fiber cable 1 has a pitch conversion unit 8, but it does not have to have a pitch conversion unit 8.

[0053] In the above embodiment, the multi-core connector 5 is attached to one end of the optical fiber ribbon 40, but it may also be attached to another end of the optical fiber ribbon 40. In this case, the flexible tube 6 may be provided at both ends of the optical fiber cable 1.

[0054] In the above embodiment, it is preferable that the diameter of the glass fiber of the optical fiber core 20 is 80 μm or more and 120 μm or less. This is because if the outer diameter of the optical fiber core 20 is, for example, about 165 μm and the glass diameter of the glass fiber of the optical fiber core 20 is about 125 μm, the coating thickness of the optical fiber core 20 will be thin, which may worsen the mechanical strength. Therefore, by setting the glass diameter of the glass fiber of the optical fiber core 20 to 80 μm or more and 120 μm or less, it is possible to suppress the thinning of the coating thickness, and as a result, it is possible to suppress the reduction in the mechanical strength of the optical fiber cable 1,1A. [Explanation of Symbols]

[0055] 1,1A: Fiber optic cable 2: Cable body 3: Outer cover material 3a: Contact part 4,4A: Subunit 5: Multi-core connector 6:Flexible tube 7: Pooling Eye 8: Pitch conversion section 10: Duct 10a: Entrance 10b:Exit 20 (20A~20L): Optical fiber core 40: Fiber optic ribbon 41:Connection part 42: Unconnected part 43: Linked resin 52: Slot Rod 54: Tension Member 55: Retaining tape 71: Circular section 72: Cylindrical part 100: Equipment 101:First metal plate 102:Second metal plate 103: Cylindrical member 400: First end

Claims

1. A cable body comprising 3000 or more optical fiber cores and an outer sheath material for housing the optical fiber cores, A multi-core connector connected to the end of the optical fiber core, The cable has a flexible tube provided at at least one end of the cable body, The multi-core connector is housed in the flexible tube. The outer diameter of the flexible tube and the outer diameter of the cable body are 60 mm or less. The allowable bending radius of the aforementioned flexible pipe is 220 mm. The aforementioned outer covering material contains silicone in a mass percentage of 0.2% or more and 1.5% or less. An optical fiber cable having a bending stiffness of 25 N·mm² or less, and the amount of variation in the bending stiffness in the circumferential direction of the optical fiber cable being within 5% of the average value of the bending stiffness.

2. The optical fiber cable according to claim 1, wherein the static friction coefficient between the outer sheath material and the stainless steel plate is 0.20 or more and 0.46 or less.

3. The optical fiber cable according to claim 1 or claim 2, wherein the cross-section of the outer sheath is polygonal.

4. The optical fiber cable according to any one of claims 1 to 3, wherein the optical fiber cores are arranged in parallel, and in some or all of the optical fiber cores, connecting portions where adjacent optical fiber cores are connected and unconnected portions where adjacent optical fiber cores are not connected are intermittently provided in the longitudinal direction, thereby forming an intermittently connected optical fiber ribbon.

5. The device further includes a pitch conversion unit provided between the first end of the optical fiber ribbon and the multi-core connector for converting the pitch of the optical fiber cores, The pitch of the optical fiber cores in the multi-core connector is longer than the pitch of the optical fiber cores in the optical fiber ribbon. The outer diameter of the optical fiber core is 160 μm or more and 185 μm or less. The core density of the cable body is 10 cores / mm². ２ The optical fiber cable described in claim 4.

6. The optical fiber cable according to any one of claims 1 to 5, wherein the glass diameter of the optical fiber core is 80 μm or more and 120 μm or less.

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