Optical cable

Abstract

To provide an optical cable with which it is possible to suppress the occurrence of a gap between a protective component and a tension member, even in the presence of manufacturing errors.SOLUTION: The optical cable comprises: an optical fiber core wire; a pair of tension members; a pair of protective components; an exterior coating covering the outer circumference of the pair of tension members and the pair of protective components; an internal resin provided in a region enclosed by the pair of tension members and the pair of protective components; and an internal notch formed in the outer circumferential surface of the internal resin. The length L of the protective components in a first direction fulfills expression (1). Expression (1): W-D≤L≤W.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to optical cables. [Background technology]

[0002] Patent Document 1 discloses an optical cable. The optical cable includes an optical fiber core, a pair of tension members, a pair of protective members, and an outer jacket. The optical cable also includes an inner resin provided in an area surrounded by the pair of tension members and the pair of protective members. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2023-44084 A Summary of the Invention [Problem to be solved by the invention]

[0004] The pair of protective members and the pair of tension members are bonded together with an adhesive. The pair of protective members are intended to protect the optical fiber core from insects, rodents, birds, and other living creatures.

[0005] Due to manufacturing errors, the protective member may become misaligned, resulting in a gap between the protective member and the tension member, which may allow insects, rodents, birds, and other creatures to penetrate and damage the optical fiber core.

[0006] In one aspect of the present disclosure, it is preferable to provide an optical cable that can suppress the occurrence of a gap between a protection member and a tension member even if a manufacturing error occurs. [Means for solving the problem]

[0007] One aspect of the present disclosure is an optical cable comprising: an optical fiber; a pair of tension members provided on either side of the optical fiber in a first direction perpendicular to the cable longitudinal direction; a pair of protective members provided on either side of the optical fiber and the pair of tension members in a second direction perpendicular to both the first direction and the cable longitudinal direction; an outer sheath covering the outer circumference of the pair of tension members and the pair of protective members; an internal resin provided in an area surrounded by the pair of tension members and the pair of protective members and covering the optical fiber; and an internal notch formed on the outer surface of the internal resin.

[0008] The length L of the protection member in the first direction satisfies the following formula (1).

[0009] Formula (1) WD≦L≦W In formula (1), W is the distance in the first direction between a point on the outer circumferential surface of one of the tension members on the opposite side to the other tension member and a point on the outer circumferential surface of the other tension member on the opposite side to the one tension member. In formula (1), D is the diameter of the tension member.

[0010] An optical cable according to one aspect of the present disclosure can suppress the occurrence of gaps between the protective member and the tension member even if manufacturing errors occur. [Brief description of the drawings]

[0011] [Figure 1] 1 is a cross-sectional view showing the configuration of an optical cable. [Diagram 2] Fig. 2A is an explanatory diagram showing the configuration of a measurement sample used for measuring adhesive strength, and Fig. 2B is an explanatory diagram showing the measurement sample during adhesive strength measurement. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Exemplary embodiments of the present disclosure will now be described with reference to the drawings. First Embodiment 1. Optical Cable 1 Configuration The configuration of optical cable 1 will be described with reference to Fig. 1. Optical cable 1 is a long linear member. Fig. 1 is a drawing showing a cross section perpendicular to the longitudinal direction of optical cable 1 (hereinafter referred to as cable longitudinal direction dL).

[0013] The optical cable 1 includes an optical fiber core 3. The optical fiber core 3 is a so-called ribbon core. The optical fiber core 3 is a linear member extending along the cable longitudinal direction dL. The optical fiber core 3 includes a plurality of optical fiber strands 5. The optical fiber strands 5 include a core, a cladding covering the outer periphery of the core, and a resin-made core coating covering the outer periphery of the cladding. The core is made of quartz glass or the like having a high refractive index. The cladding is made of quartz glass or the like having a lower refractive index than the core. The optical fiber core 3 is used, for example, for communication. The optical fiber core 3 is, for example, a multimode optical fiber, a single mode optical fiber, or the like.

[0014] The optical cable 1 includes a pair of tension members 7A and 7B. The tension members 7A and 7B are linear members extending along the cable longitudinal direction dL. A first direction d1 shown in FIG. 1 is a direction perpendicular to the cable longitudinal direction dL. The tension members 7A and 7B are provided on both sides of the optical fiber 3 in the first direction d1.

[0015] The tension members 7A and 7B are vertically attached to the optical fiber 3. A gap is provided between the tension members 7A and 7B and the optical fiber 3. The tension members 7A and 7B have a function of resisting a tensile force acting on the optical cable 1. The tension members 7A and 7B are made of highly rigid wire material such as solid or stranded steel wire, fiber reinforced plastics (FRP), aramid fiber, Kevlar (registered trademark) fiber, etc.

[0016] The cross-sectional shape of the tension members 7A, 7B is circular. The diameter of the tension members 7A, 7B is D. D is, for example, 0.4 mm or more and 1.4 mm or less. The direction perpendicular to the first direction d1 and the cable longitudinal direction dL is the second direction d2. The diameter D is greater than the thickness in the second direction d2 of the optical fiber cores 3 stacked in the second direction d2. When viewed from the first direction d1, the area where the optical fiber cores 3 exist is included in the area where the tension members 7A, 7B exist.

[0017] The optical cable 1 includes a pair of protective members 9C and 9D. The protective members 9C and 9D are strip-shaped members extending along the cable longitudinal direction dL. In a cross section, the protective members 9C and 9D extend along the first direction d1.

[0018] In the second direction d2, the protective members 9C and 9D are provided on both sides of the optical fiber 3 and the pair of tension members 7A and 7B. The protective members 9C, 9D are, for example, members formed by forming a metal, an alloy, or the like into a tape shape. The protective members 9C, 9D are, for example, configured as a laminate tape made of stainless steel, iron, or the like. The protective members 9C, 9D are attached vertically to the optical fiber core 3 and the pair of tension members 7A, 7B. The length L of the protective members 9C, 9D in the first direction d1 is, for example, 5 mm or more and 8 mm or less. The thickness of the protective members 9C, 9D in the second direction d2 is, for example, 0.10 mm or more and 0.25 mm or less.

[0019] The protective members 9C and 9D are fixed to the tension members 7A and 7B, for example, via the internal resin 21. For example, the protective members 9C and 9D are fixed near their ends in the first direction d1 and the tension members 7A and 7B are fixed near their ends in the second direction d2.

[0020] For example, the protective members 9C and 9D are bonded to the internal resin 21 by an adhesive. Also, for example, the protective members 9C and 9D are bonded to the outer cover 11 by an adhesive. For example, the adhesive may be a hot melt adhesive that melts when heated.

[0021] For example, adhesive is provided on both sides of the protection members 9C and 9D. In addition, the adhesive is provided, for example, over substantially the entire length of the protection members 9C and 9D in the cable longitudinal direction dL.

[0022] The length L satisfies the following formula (1). Formula (1) WD≦L≦W In formula (1), W is the distance from the outer circumferential surface of tension member 7A to the outer circumferential surface of tension member 7B. That is, W is the distance in the first direction d1 between points 7X and 7Y shown in FIG. 1. Point 7X is a point on the outer circumferential surface of tension member 7A on the opposite side to tension member 7B. Point 7Y is a point on the outer circumferential surface of tension member 7B on the opposite side to tension member 7A. Note that tension member 7A corresponds to one tension member, and tension member 7B corresponds to the other tension member.

[0023] The optical cable 1 includes an outer jacket 11. The outer jacket 11 covers the outer periphery of other components in the optical cable 1. The components covered by the outer jacket 11 include a pair of tension members 7A, 7B, a pair of protective members 9C, 9D, the optical fiber 3, water-absorbent strings 19A, 19B described below, and an internal resin 21.

[0024] 1 is, for example, 9.5 mm to 12.0 mm in the first direction d1, and the thickness TO of the outer jacket 11 is, for example, 4.0 mm to 7.0 mm in the second direction d2. In the first direction d1, the width of the internal resin 21 is greater than the distance W, for example, at least the distance W+0.2 mm and at most the distance W+1.0 mm. In the second direction d2, the thickness of the internal resin 21 is greater than the diameter D of the tension members 7A, 7B, for example, at least the diameter D+0.2 mm and at most the diameter D+1.0 mm.

[0025] The jacket 11 is composed of a jacket central portion 13 and jacket end portions 15. The jacket central portion 13 is a portion that covers the protective members 9C and 9D and extends in the first direction d1 in a cross section. The jacket end portions 15 are portions formed on both sides of the jacket central portion 13 in a cross section.

[0026] In a cross section, the outer peripheral surface of the outer jacket central portion 13 is flat. The outer peripheral surface of the outer jacket central portion 13 is parallel to the first direction d1. In a cross section, the shape of the outer peripheral surface of the outer jacket end portion 15 is a substantially arc-shaped surface that bulges outward. The substantially arc-shaped surface that bulges outward corresponds to a curved surface that bulges outward. The outer peripheral surface of the outer jacket 11 is flat or a curved surface that bulges outward in any part. No notches are formed in the outer peripheral surface of the outer jacket 11. In the cross section, the shape of the outer circumferential surface of the optical cable 1 is the shape of the outer circumferential surface of the jacket 11. In the cross section, the shape of the outer circumferential surface of the jacket 11 is a track shape. A track shape is a shape in which the ends of two parallel lines are connected by an outwardly bulging curve. In the cross section, the outer circumferential surface of the jacket central portion 13 is flat, so that the outer circumferential surface in the cross section of the optical cable 1 is a track shape having a flat portion.

[0027] The optical cable 1 includes water-absorbing strings 19A and 19B. The water-absorbing strings 19A and 19B are linear members extending along the cable longitudinal direction dL. The water-absorbing string 19A is provided between the optical fiber 3 and the tension member 7A. The distance between the water-absorbing string 19A and the optical fiber 3 is smaller than the distance between the water-absorbing string 19A and the tension member 7A. The water-absorbing strings 19A and 19B are made of, for example, polyester fiber with a water-absorbent polymer attached to the surface.

[0028] The water absorbing string 19B is provided between the optical fiber 3 and the tension member 7B. The distance between the water absorbing string 19B and the optical fiber 3 is smaller than the distance between the water absorbing string 19B and the tension member 7B. The water absorbing strings 19A and 19B are attached vertically to the optical fiber 3 and are in contact with the optical fiber 3. The water absorbing strings 19A and 19B have the function of improving the waterproofness of the optical fiber 3.

[0029] The optical cable 1 includes an internal resin 21. The internal resin 21 is provided in an area surrounded by the tension members 7A and 7B and the protective members 9C and 9D. The internal resin 21 covers the optical fiber 3 and the water-absorbing strings 19A and 19B. The internal resin 21 also covers a portion of the outer circumferential surface of the tension member 7A that is opposite to the tension member 7B. The internal resin 21 also covers a portion of the outer circumferential surface of the tension member 7B that is opposite to the tension member 7A.

[0030] The resin constituting the internal resin 21 is preferably a resin having a high melt flow rate (MFR) so that the optical cable 1 has a predetermined characteristic. The melt flow rate of the resin constituting the internal resin 21 is, for example, 0.5 g / 10 min or more. There is no particular upper limit for the melt flow rate. Here, the MFR is a value measured under conditions of 190° C. and 21.18 N based on JIS K7210. The resin constituting the outer jacket 11 is not particularly limited, and may be the same resin as the resin constituting the internal resin 21, or may be a different resin. In addition, the optical cable 1 may be made flame retardant by adding a flame-retardant filler to the internal resin 21 and the outer jacket 11. Examples of the flame-retardant filler include magnesium hydroxide. More flame-retardant filler may be added to the outer jacket 11 than to the internal resin 21. For example, the internal resin 21 is made of low-density polyethylene, and the outer jacket 11 is made of linear low-density polyethylene resin.

[0031] Internal notches 23, 25, 27, and 29 are formed on the outer circumferential surface of the internal resin 21. Each of the internal notches 23, 25, 27, and 29 is a recess that is V-shaped in cross section. Each of the internal notches 23, 25, 27, and 29 is formed long along the cable longitudinal direction dL.

[0032] The absorbent string 19A and the internal notches 23, 25 are aligned in the second direction d2. The absorbent string 19A is located on an extension line of the tips of the V-shaped recesses of the internal notches 23, 25 extended in the second direction d2.

[0033] The absorbent string 19B and the internal notches 27, 29 are aligned in the second direction d2. The absorbent string 19B is located on an extension line of the tips of the V-shaped recesses of the internal notches 27, 29 extended in the second direction d2.

[0034] When the end of the optical cable 1 is disassembled to take out the optical fiber 3 from the optical cable 1, the internal resin 21 can be cut using any one of the internal notches 23, 25, 27, and 29 as a starting point.

[0035] It is preferable that the adhesive strength between the jacket 11 and the protective members 9C, 9D is 2 N / mm or more. When the adhesive strength is 2 N / mm or more, the jacket 11 is unlikely to peel off from the protective members 9C, 9D even when the optical cable 1 is bent and then bent back in the opposite direction. Also, when the adhesive strength is 2 N / mm or more, the jacket 11 is unlikely to peel off from the protective members 9C, 9D even when the optical cable 1 is bent in the second direction d2 with a small radius of curvature (for example, a radius of curvature 10 times the thickness TO of the jacket 11). For the same reason, it is preferable that the adhesive strength between the internal resin 21 and the protective members 9C, 9D is 2 N / mm or more. When the adhesive strength is 2 N / mm or more, the protective members 9C, 9D are unlikely to peel off from the internal resin 21 even when the optical cable 1 is bent and then bent back in the opposite direction.

[0036] The adhesive strength between the outer jacket 11 and the protective members 9C, 9D is more preferably 3 N / mm or more, and particularly preferably 4 N / mm or more. The higher the adhesive strength between the outer jacket 11 and the protective members 9C, 9D, the more difficult it is for the outer jacket 11 to peel off from the protective members 9C, 9D. The adhesive strength between the internal resin 21 and the protective members 9C, 9D is more preferably 3 N / mm or more, and particularly preferably 4 N / mm or more. The higher the adhesive strength between the internal resin 21 and the protective members 9C, 9D, the more difficult it is for the protective members 9C, 9D to peel off from the internal resin 21.

[0037] The adhesive strength is measured as follows. A measurement sample S shown in FIG. 2A is cut out from the optical cable 1. The measurement sample S is composed of the outer sheath 11 and the protective member 9C or the protective member 9D. The shape of the measurement sample S is rectangular. The length of the long side of the measurement sample S is 300 mm, and the lengths of the short sides 31 and 32 are each 6 mm. The adhesive strength between the protective members 9C and 9D and the internal resin 21 can also be measured in the same manner using a measurement sample composed of the internal resin 21 and the protective member 9C or the protective member 9D.

[0038] In the measurement sample S, in a portion that is more than 130 mm away from the short side 31, the protective member 9C or the protective member 9D has peeled off from the outer jacket 11. In the other portions, the protective member 9C or the protective member 9D has not yet peeled off from the outer jacket 11.

[0039] In the region where protective member 9C or protective member 9D is bonded to outer covering 11, the line closest to short side 32 is defined as boundary line 34. Boundary line 34 is a straight line parallel to short sides 31 and 32. In the initial state, the distance from short side 31 to boundary line 34 is 130 mm.

[0040] Of the measurement sample S, the outer covering 11 is fixed to a first chuck of a peel tester. Of the protective member 9C or protective member 9D, a tip 33 of an already peeled portion is fixed to a second chuck of the peel tester. The second chuck is moved in a direction ds shown in FIG. 2B at a speed of 100 mm / min relative to the first chuck. The direction ds is a direction from the short side 32 toward the short side 31. At this time, the boundary line 34 moves in the direction of the short side 31.

[0041] The average value of the force F required to move the second chuck is measured when the distance from the short side 31 to the boundary line 34 is between 110 mm and 60 mm. The unit of the force F is N / 6 mm. The adhesive strength (N / mm) between the outer cover 11 and the protective members 9C and 9D is calculated by dividing the average value of the force F by 6. Here, "6" is the length of the short sides 31 and 32 in mm.

[0042] When the protective members 9C, 9D are bonded to the outer covering 11 and the internal resin 21 with a hot melt adhesive or the like, the higher the temperature of the resin when the outer covering 11 is extruded, the stronger the adhesive strength between the protective members 9C, 9D and the outer covering 11 and the internal resin 21. When the protective members 9C, 9D and the outer covering 11 and the internal resin 21 are bonded to each other with a hot melt adhesive or the like, the greater the film thickness of the outer covering 11 during extrusion molding, the greater the heat capacity of the resin during extrusion molding, and the stronger the adhesive strength between the protective members 9C, 9D and the outer covering 11 and the internal resin 21.

[0043] The optical cable 1 can be installed, for example, in a subway station or the like. The optical cable 1 can be used, for example, as wiring in a data center or between data centers. The optical cable 1 can be used, for example, as a so-called drop cable.

[0044] 2. Benefits of Optical Cable 1 (1A) The length L of the protective members 9C, 9D is equal to or greater than WD. Therefore, even if the positions of the protective members 9C, 9D are shifted in the first direction d1 due to manufacturing errors, gaps are unlikely to occur between the protective members 9C, 9D and the tension members 7A, 7B. In other words, the optical fiber 3 is surrounded by the protective members 9C, 9D and the tension members 7A, 7B. As a result, even if the positions of the protective members 9C, 9D are shifted in the first direction d1, damage to the optical fiber 3 caused by creatures such as insects, rodents, and birds can be suppressed.

[0045] The length L of the protective members 9C, 9D is equal to or less than W. Therefore, the protective members 9C, 9D can be prevented from protruding excessively in the first direction d1. (1B) The optical cable 1 is provided with water-absorbing strings 19A and 19B. Therefore, the optical fiber 3 has high waterproofing.

[0046] (1C) The optical cable 1 has internal notches 23, 25, 27, and 29. When the end of the optical cable 1 is disassembled to take out the optical fiber 3 from the optical cable 1, the internal resin 21 can be cut using any of the internal notches 23, 25, 27, and 29 as a starting point.

[0047] (1D) The water absorbent string 19A and the internal notches 23, 25 are aligned in the second direction d2. The water absorbent string 19B and the internal notches 27, 29 are aligned in the second direction d2. Therefore, when the blade of a cutter or nippers is inserted into the internal notches 23, 25, 27, 29, the water absorbent strings 19A, 19B act as a buffer material, preventing the optical fiber 3 from being damaged by the blade. In addition, the cutting distance of the internal resin 21 (i.e., the distance from the internal notches 23, 25, 27, 29 to the water absorbent strings 19A, 19B) can be shortened, making it easier to remove the optical fiber 3.

[0048] (1E) The outer peripheral surface in the cross section of the optical cable 1 has a flat portion. For example, when dismantling the terminal of the optical cable 1 to extract the optical fiber 3 from the optical cable 1, the optical cable 1 can be held so that the flat portion is in contact with the surface of a workbench. In this case, the optical cable 1 is less likely to move on the workbench, making the work easier.

[0049] (1F) The tension members 7A, 7B and the protective members 9C, 9D can be made of highly rigid members. In this case, a cutter blade or the like can be inserted between the tension members 7A, 7B and the protective members 9C, 9D and moved along the cable longitudinal direction dL. At this time, the tension members 7A, 7B and the protective members 9C, 9D function to guide the cutter blade or the like. Therefore, even if no notch is formed on the outer circumferential surface of the jacket 11, it is easy to separate the jacket 11 and the protective members 9C, 9D from other parts.

[0050] (1G) No notches are formed on the outer circumferential surface of the jacket 11. This further prevents the jacket 11 from being damaged. (1H) The adhesive strength between the jacket 11 and the protective members 9C, 9D is, for example, 2 N / mm or more. In this case, even if the optical cable 1 is bent and then bent back in the opposite direction, the jacket 11 is unlikely to peel off from the protective members 9C, 9D. In addition, even if the optical cable 1 is bent with a large curvature, the jacket 11 is unlikely to peel off from the protective members 9C, 9D.

[0051] 3. Tests on adhesion and peeling between the outer cover 11 and the protective members 9C and 9D Two types of optical cables 1 were prepared. A measurement sample S1 was prepared from one of the optical cables 1 by the above-mentioned method, and the adhesive strength between the outer jacket 11 and the protective members 9C, 9D was measured. A measurement sample S2 was prepared from the other optical cable 1 by the above-mentioned method, and the adhesive strength between the outer jacket 11 and the protective members 9C, 9D was measured. Each optical cable 1 was visually evaluated for whether the outer jacket 11 peeled off from the protective members 9C, 9D and whether the protective members 9C, 9D peeled off from the internal resin 21 when bent in the second direction d2 with a curvature radius 10 times the thickness TO of the outer jacket 11. The evaluation results are shown in Table 1.

[0052] [Table 1]

[0053] When the adhesive strength was 4.1 N / mm, the outer jacket 11 did not peel off from the protective members 9C and 9D, and the protective members 9C and 9D did not peel off from the internal resin 21. When the adhesive strength was 1.2 N / mm, the outer jacket 11 peeled off from the protective members 9C and 9D. <Other embodiments> Although the embodiments of the present disclosure have been described above, the present disclosure is not limited to the above-described embodiments and can be implemented in various modified forms.

[0054] (1) The function of one component in each of the above embodiments may be shared by multiple components, or the functions of multiple components may be performed by one component. Also, part of the configuration of each of the above embodiments may be omitted. Also, at least part of the configuration of each of the above embodiments may be added to or substituted for the configuration of another of the above embodiments.

[0055] (2) In addition to the optical cable 1 described above, the present disclosure can be realized in various forms, such as a system including the optical cable 1 as a component, a method for manufacturing the optical cable 1, and the like. [Explanation of symbols]

[0056] 1...optical cable, 3...optical fiber core, 5...optical fiber strand, 7A, 7B...tension member, 7X, 7Y...point, 9C, 9D...protective member, 11...outer jacket, 13...center of outer jacket, 15...end of outer jacket, 19A, 19B...absorbent string, 21...internal resin, 23, 25, 27, 29...internal notch, 31, 32...short side, 33...tip, 34...boundary line

Claims

1. An optical fiber core; a pair of tension members provided on both sides of the optical fiber in a first direction perpendicular to a cable longitudinal direction; a pair of protection members provided on both sides of the optical fiber and the pair of tension members in a second direction perpendicular to both the first direction and the cable longitudinal direction; an outer cover covering an outer periphery of the pair of tension members and the pair of protection members; an inner resin provided in an area surrounded by the pair of tension members and the pair of protective members and covering the optical fiber; an internal notch formed on an outer peripheral surface of the internal resin; An optical cable comprising: The length L of the protective member in the first direction satisfies the following formula (1): Optical cable. Formula (1) WD≦L≦W In formula (1), W is the distance in the first direction between a point on the outer circumferential surface of one of the tension members on the opposite side to the other tension member and a point on the outer circumferential surface of the other tension member on the opposite side to the one tension member. In formula (1), D is the diameter of the tension member.

2. 2. The optical cable according to claim 1, The outer peripheral surface of the outer jacket is a flat surface or a curved surface that bulges outward at any part. Optical cable.

3. 3. The optical cable according to claim 1, The optical fiber cable may further include a water-absorbing string provided between the optical fiber cable and the tension member. The absorbent string and the internal notch are aligned in the second direction. Optical cable.

4. 3. The optical cable according to claim 1, The adhesive strength between the outer cover and the protective member is 2 N / mm or more. Optical cable.

5. 3. The optical cable according to claim 1, The outer circumferential surface of the optical cable in cross section is in a track shape having a flat portion. Optical cable.

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