Optical fiber cable and method for manufacturing optical fiber cable

Abstract

An optical fiber cable (1) is provided with: a cable body (10) provided with optical fibers (21); an outer sheath (70) and a reinforcing sheet (60) for accommodating the cable body (10); and ripcords (50A, 50B) disposed in a space (65) formed between the cable body (10) and the reinforcing sheet (60). The reinforcing sheet (60) is partially in contact with the cable body (10) while keeping elastic deformation of the cable body (10) toward the inside of the cable body (10).

Description

Optical fiber cable and method of manufacturing the same

[0001] The present invention relates to an optical fiber cable and a method for manufacturing an optical fiber cable. For designated states where incorporation by reference of documents is permitted, the content of Japanese Patent Application No. 2023-044714 filed in Japan on March 20, 2023 is incorporated by reference into this specification and made a part of the description of this specification.

[0002] An optical fiber cable is known that includes a cable body, an outer sheath that houses the cable body, a reinforcing sheet provided between the cable body and the outer sheath, and a rip cord provided between the reinforcing sheet and the cable body (see, for example, Patent Document 1).

[0003] JP 2017-72801 A

[0004] In the above-mentioned optical fiber cable, a space is formed between the cable body and the reinforcing sheet that extends around the entire circumferential direction of the cable, and the ripcord is disposed in this space. Therefore, when the reinforcing sheet is to be torn using the ripcord, the ripcord moves within the space between the cable body and the reinforcing sheet, making the tearing operation difficult.

[0005] The problem that the present invention aims to solve is to provide an optical fiber cable and a method for manufacturing an optical fiber cable that can improve the workability of tearing operations by limiting the circumferential movement of the rip cord within a certain range.

[0006] [1] Aspect 1 of the present invention is an optical fiber cable comprising a cable body having an optical fiber, a protective layer that houses the cable body, and a rip cord arranged in a space formed between the cable body and the protective layer, wherein the protective layer is in partial contact with the cable body while maintaining elastic deformation of the cable body toward the inside of the cable body.

[0007] [2] A second aspect of the present invention may be the optical fiber cable of the first aspect, which satisfies the following formula (1): 45°≦θ≦135° (1) where θ is the angle of intersection between an imaginary line passing through the center of the optical fiber cable and the ripcord and the direction of the elastic deformation.

[0008] [3] Aspect 3 of the present invention may be an optical fiber cable according to aspect 1 or 2, wherein the radial distance of the optical fiber cable in the space is equal to or less than the outer diameter of the ripcord.

[0009] [4] Aspect 4 of the present invention may be an optical fiber cable according to aspect 1, wherein the radial distance of the optical fiber cable in the space is equal to or less than the outer diameter of the rip cord, and the direction of the rip cord and the direction of the elastic deformation overlap in the circumferential direction of the optical fiber cable.

[0010] [5] Aspect 5 of the present invention may be an optical fiber cable in any one of aspects 1 to 4, in which, in a cross section perpendicular to the extension direction of the optical fiber cable, a portion of the minor axis on the inner surface of the protective layer and a portion of the minor axis on the outer surface of the cable body are in contact with each other.

[0011] [6] Aspect 6 of the present invention is an optical fiber cable according to any one of aspects 1 to 5, wherein the protective layer comprises a reinforcing sheet covering the outer periphery of the cable body and a sheath covering the outer periphery of the reinforcing sheet, and the reinforcing sheet may be in partial contact with the cable body.

[0012] [7] Aspect 7 of the present invention is an optical fiber cable according to aspect 6, wherein the reinforcing sheet has a lap portion in which the ends of the reinforcing sheet overlap, and the lap portion and the rip cord may be offset from each other in the circumferential direction of the optical fiber cable.

[0013] [8] Aspect 8 of the present invention may be an optical fiber cable in which, in any one of aspects 1 to 7, the radial thickness of the contact portion of the protective layer with the cable main body is thicker than the radial thickness of other portions of the protective layer.

[0014] [9] A ninth aspect of the present invention may be an optical fiber cable according to any one of the first to eighth aspects, wherein the deformation rate Cr of the cable main body relative to the cable main body in an unloaded state satisfies the following formula (2): 4.1%≦Cr≦16.2% (2)

[0015]

[10] A tenth aspect of the present invention may be an optical fiber cable according to any one of the first to ninth aspects, wherein the recovery rate Rr of the cable main body in an unloaded state satisfies the following formula (3): 106%≦Rr≦131% (3).

[0016]

[11] Aspect 11 of the present invention may be an optical fiber cable in any one of aspects 1 to 10, wherein the protective layer has an inner surface on which no groove extending along the extension direction of the optical fiber cable is formed.

[0017]

[12] Aspect 12 of the present invention may be an optical fiber cable in any one of aspects 1 to 11, wherein the cable body has an outer surface on which no grooves extending along the extension direction of the optical fiber cable are formed.

[0018]

[13] Aspect 13 of the present invention is a method for manufacturing an optical fiber cable, comprising: a first step of preparing a cable body having an optical fiber; a second step of arranging a rip cord along the outer peripheral surface of the cable body; and a third step of encasing the cable body and the rip cord in the protective layer and pressing and deforming the cable body.

[0019]

[14] Aspect 14 of the present invention may be a method for manufacturing an optical fiber cable according to aspect 13, wherein the protective layer comprises a reinforcing sheet covering the outer periphery of the cable body and a sheath covering the outer periphery of the reinforcing sheet, and the third step may include, after accommodating the cable body and the ripcord in the reinforcing sheet, deforming the cable body by pressing the reinforcing sheet in a direction that does not overlap with the ripcord within the radial direction of the optical fiber cable.

[0020] In the present invention, the protective layer is in partial contact with the cable body while maintaining the elastic deformation of the cable body toward the inside of the cable body, thereby limiting the movement of the rip cord along the circumferential direction of the optical fiber cable within a certain range, thereby improving the workability of the tearing operation.

[0021] Furthermore, in the present invention, when manufacturing an optical fiber cable, the cable body is housed in a protective layer and the cable body is pressed and deformed, thereby making it possible to manufacture an optical fiber cable in which the movement of the ripcord along the circumferential direction of the optical fiber cable is limited within a certain range.

[0022] Fig. 1 is a cross-sectional view showing an optical fiber cable according to an embodiment of the present invention. Fig. 2 is a diagram showing a manufacturing apparatus for manufacturing an optical fiber cable according to an embodiment of the present invention. Fig. 3 is a cross-sectional view showing an optical fiber cable according to another embodiment of the present invention.

[0023] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0024] FIG. 1 is a cross-sectional view showing an optical fiber cable 1 according to an embodiment of the present invention.

[0025] As shown in FIG. 1, the optical fiber cable 1 of this embodiment includes a cable main body 10, ripcords 50A and 50B, a reinforcing sheet 60, an outer sheath 70, and tension members 80A to 80D. The optical fiber cable 1 extends along a normal to the plane of FIG. 1, and FIG. 1 shows a cross section perpendicular to the extension direction (axial direction) of the optical fiber cable 1. The reinforcing sheet 60 and the outer sheath 70 correspond to an example of a "protective layer" in the present invention. This protective layer covers the outer periphery of the cable main body 10 and houses the cable main body 10. As will be described later, the optical fiber cable 1 does not necessarily have to include the reinforcing sheet 60. In this case, the outer sheath 70 corresponds to an example of a "protective layer" in the present invention.

[0026] The cable main body 10 includes an optical fiber assemblage 20, an inner sheath 30, and a holding winding tape 40. The cable main body 10 does not necessarily have to include the holding winding tape 40. The optical fiber assemblage 20 is formed by assembling a plurality of optical fibers 21 extending along the axial direction of the optical fiber cable 1.

[0027] Although not particularly limited, the optical fiber assemblage 20 of this embodiment includes a plurality of optical fiber units. Each optical fiber unit is formed by bundling a plurality of optical fiber ribbons with a bundling material. Each optical fiber ribbon is an intermittently bonded optical fiber ribbon in which a plurality of optical fibers (optical fiber strands) 21 are arranged in parallel and intermittently connected. The bundling material is wound in a mesh-like or spiral pattern around the outer periphery of the bundle of a plurality of optical fiber ribbons.

[0028] Then, a plurality of optical fiber units are twisted together to form an optical fiber assemblage. Specific examples of twisting methods for optical fiber units include SZ twisting and unidirectional twisting. SZ twisting is a twisting method in which a plurality of linear bodies are twisted together while reversing the twisting direction at predetermined intervals. Unidirectional twisting is a twisting method in which a plurality of linear bodies are twisted in only one direction, and is a twisting method in which a plurality of linear bodies are twisted together in a spiral shape.

[0029] The configuration of the optical fiber unit is not particularly limited to the above. For example, the optical fiber unit may be configured by twisting together a plurality of optical fiber ribbons without using a bundling material. Alternatively, the optical fiber unit may be configured by bundling or twisting together a plurality of optical fiber strands instead of an optical fiber ribbon. Alternatively, the optical fiber unit may be configured by bundling or twisting together a plurality of optical fiber ribbons or a plurality of optical fiber strands to form a unit intermediate, and bundling or twisting together a plurality of such unit intermediates.

[0030] Furthermore, the configuration of the optical fiber assemblage 20 is not particularly limited to the above. For example, instead of a plurality of optical fiber units, the optical fiber assemblage may be configured with a single optical fiber unit formed by bundling or twisting a plurality of optical fiber ribbons or a plurality of optical fiber strands.

[0031] The inner sheath 30 is a cylindrical member that covers the outer periphery of the optical fiber assemblage 20. The inner sheath 30 is made of an elastically deformable material. Although not particularly limited, specific examples of the material that constitutes the inner sheath 30 include resin materials such as polyvinyl chloride (PVC), polyethylene (PE), nylon, ethylene fluoride, and polypropylene (PP).

[0032] The holding winding tape 40 covers the outer periphery of the inner sheath 30. In this embodiment, the holding winding tape 40 is longitudinally wrapped around the outer periphery of the inner sheath 30. Specifically, the holding winding tape 40 is wrapped around the outer periphery of the inner sheath 30 so that the longitudinal direction of the holding winding tape 40 substantially coincides with the axial direction of the optical fiber cable 1 and the width direction of the holding winding tape 40 substantially coincides with the circumferential direction of the optical fiber cable 1. Note that the wrapping method of the holding winding tape 40 is not limited to the longitudinal wrapping described above, and may be, for example, horizontal wrapping (spiral wrapping). Furthermore, the outer periphery of the inner sheath 30 may be covered with a plurality of holding winding tapes 40, or the holding winding tape 40 may have a folded-back portion.

[0033] In addition to the holding tape (outer holding tape) 40, the outer periphery of the optical fiber assemblage 20 may be covered with a holding tape (inner holding tape) 22, and the holding tape 22 may be interposed between the optical fiber assemblage 20 and the inner sheath 30. In this case, the cable main 10 includes the holding tape 22. Note that the cable main 10 does not need to include the holding tape 22. Furthermore, in addition to ripcords (outer ripcords) 50A and 50B described below, a ripcord (inner ripcord) 23 may be interposed between the holding tape 22 covering the outer periphery of the optical fiber assemblage 20 and the inner sheath 30. In this case, the cable main 10 includes the ripcord 23. By tearing the inner sheath 30 with the ripcord 23, the optical fibers 21 can be extracted to the outside from the optical fiber cable 1. Note that the cable main 10 does not need to include the ripcord 23.

[0034] The holding winding tape 40 is made of a nonwoven fabric or a film. Specific examples of the nonwoven fabric that makes up the holding winding tape 40 are not particularly limited, but include nonwoven fabrics made of fibers such as polyester, polyethylene, or polypropylene. Specific examples of the film that makes up the holding winding tape 40 are not particularly limited, but include films made of resins such as polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), or nylon.

[0035] When the holding winding tape 40 is made of a nonwoven fabric, water-absorbing powder may be applied to the nonwoven fabric so that the holding winding tape 40 functions as a water-absorbing layer for stopping water from entering the cable main body 10. When water penetrates the cable main body 10, the water-absorbing powder swells and seals gaps in the cable main body 10, thereby stopping water from entering the cable main body 10.

[0036] Specific examples of such water-absorbing powders include, but are not limited to, highly absorbent materials such as starch-based, cellulose-based, polyacrylic acid-based, polyvinyl alcohol-based, and polyoxyethylene-based materials, as well as mixtures thereof. The water-absorbing powder may be applied to the nonwoven fabric by adhering (coating) it on the surface of the nonwoven fabric, or by being interposed between two sheets of nonwoven fabric.

[0037] The cable main body 10 is only required to include at least one optical fiber, and the configuration of the cable main body 10 is not particularly limited to the above. For example, the cable main body 10 described above has a so-called slotless structure, but the cable main body 10 may also have a loose tube or slot type configuration. In this embodiment, the housing member that houses the optical fiber is the inner sheath 30. Although not particularly limited, the elastic deformation of this housing member accounts for the majority of the elastic deformation of the case main body 10, which will be described later. On the other hand, when the cable main body 10 has a loose tube type configuration, a tube that houses the optical fiber corresponds to an example of the housing member. Furthermore, when the cable main body 10 has a slot type configuration, a slot rod having a groove that houses the optical fiber corresponds to an example of the housing member.

[0038] The pair of rip cords 50A, 50B are string-like members (tear cords) for tearing the reinforcing sheet 60 and the outer sheath 70 when extracting the cable main 10 from the optical fiber cable 1 at the intermediate portion or terminal portion of the optical fiber cable 1. Each of the rip cords 50A, 50B extends along the axial direction of the optical fiber cable 1. The pair of rip cords 50A, 50B extend substantially parallel to each other and face each other, sandwiching the cable main 10 therebetween.

[0039] Each of the ripcords 50A, 50B is made of, but not limited to, fibers such as polyester, polyimide, aramid, or glass, or an aggregate of fibers such as a twisted yarn made by twisting together such fibers. Ripcords 50A, 50B may also be made of the above fibers or twisted yarns impregnated with resin.

[0040] The reinforcing sheet 60 covers the outer periphery of the cable body 10 to protect the cable body 10. This reinforcing sheet 60 prevents the cable body 10 from being damaged when the optical fiber cable 1 is bitten by an animal, for example.

[0041] Although not specifically shown, the reinforcing sheet 60 has a corrugated shape. Specifically, this corrugated shape is formed by annular peaks and valleys along the circumferential direction of the optical fiber cable 1, which are alternately arranged in the axial direction of the optical fiber cable 1. The reinforcing sheet 60 having such a corrugated shape imparts flexibility to the reinforcing sheet 60. Note that the corrugated shape may be formed by peaks and valleys that each extend spirally. Furthermore, the reinforcing sheet 60 does not have to have a corrugated shape.

[0042] The inner peripheral surface of this reinforcing sheet 60 does not have grooves formed therein that extend along the axial direction of the optical fiber cable 1 and that can accommodate the above-mentioned ripcords 50A, 50B. Furthermore, the outer peripheral surface of the above-mentioned cable main 10 (specifically, the outer peripheral surface of the holding winding tape 40) does not have grooves formed therein that extend along the axial direction of the optical fiber cable 1 and that can accommodate the above-mentioned ripcords 50A, 50B. Therefore, the ripcords 50A, 50B are disposed in a space 65 (described below) formed between this reinforcing sheet 60 and the cable main 10.

[0043] Although not specifically shown, the reinforcing sheet 60 includes a sheet body and resin films laminated on both sides of the sheet body. The sheet body may be, for example, a metal sheet, a fiber sheet, or a fiber-reinforced plastic (FRP) sheet. Examples of materials that can be used for the metal sheet include iron, iron alloys including stainless steel, aluminum, aluminum alloys, copper, and copper alloys. Examples of materials that can be used for the fiber sheet include glass fiber and aramid fiber. Examples of resin films that can be used include a hot-melt adhesive film. The reinforcing sheet 60 does not necessarily have to include a resin film.

[0044] The reinforcing sheet 60 is formed into a cylindrical shape by being wrapped longitudinally around the cable main 10. Specifically, the reinforcing sheet 60 is wrapped around the outer periphery of the cable main 10 so that the longitudinal direction of the reinforcing sheet 60 substantially coincides with the axial direction of the optical fiber cable 1 and the width direction of the reinforcing sheet 60 substantially coincides with the circumferential direction of the optical fiber cable 1. The reinforcing sheet 60 is bonded (thermally fused) to the outer sheath 70 by an outer resin film provided on the reinforcing sheet 60. In addition, in the circumferential direction of the optical fiber cable 1, a first end 61 of the reinforcing sheet 60 overlaps with a second end 62 of the reinforcing sheet 60, thereby forming a lap portion 63 of the reinforcing sheet 60. In the lap portion 63, the outer and inner resin films provided on the reinforcing sheet 60 are bonded (thermally fused) to each other.

[0045] The wrap portion 63 of the reinforcing sheet 60 is disposed near the tension members 80A, 80B in the circumferential direction of the optical fiber cable 1. The wrap portion 63 may overlap the tension members 80A, 80B in the circumferential direction of the optical fiber cable 1. Alternatively, the wrap portion 63 does not overlap the ripcords 50A, 50B in the circumferential direction of the optical fiber cable 1, and the wrap portion 63 and the ripcords 50A, 50B are offset from each other in the circumferential direction of the optical fiber cable 1. By not overlapping the wrap portion 63 of the reinforcing sheet 60 with the ripcords 50A, 50B in this manner, it is possible to prevent the ripcords 50A, 50B disposed in the space 65 from being cut by the edge of the reinforcing sheet 60. When the reinforcing sheet 60 is wrapped around the cable main 10 in a cylindrical shape, the reinforcing sheet 60 may not have the wrap portion 53 formed thereon, and the first end 61 and the second end 62 of the reinforcing sheet 60 may be butted against each other.

[0046] The outer sheath 70 is a tubular member that covers the outer periphery of the reinforcing sheet 60. Examples of materials that can be used to form the outer sheath 70 include resin materials such as polyvinyl chloride (PVC), polyethylene (PE), nylon, ethylene fluoride, polypropylene (PP), and polyolefin resins, as well as mixtures of these resin materials. Additives such as flame retardants and stabilizers may be added to the above-mentioned resin materials.

[0047] A plurality of (four in this example) tension members (tensile strength members) 80A-80D are embedded inside the outer sheath 70. The tension members 80A-80D are linear components extending in the extension direction of the optical fiber cable 1. When stress is applied to the optical fiber cable 1 in the extension direction of the optical fiber cable 1, these tension members 80A-80D bear the stress, thereby suppressing the application of stress and strain to the optical fibers 21. Note that the optical fiber cable 1 does not necessarily have to include the tension members 80A-80D. Alternatively, the tension members do not have to be embedded in the outer sheath 70; for example, the tension members may be embedded in the inner sheath 30.

[0048] The tension members 80A, 80B are adjacent to each other along the circumferential direction of the optical fiber cable 1. The tension members 80C, 80D are also adjacent to each other along the circumferential direction of the optical fiber cable 1. The tension members 80A, 80B and the tension members 80C, 80D face each other with the cable main body 10 in between.

[0049] The number of tension members included in the optical fiber cable 1 is not particularly limited to the above. Furthermore, the arrangement of the tension members inside the outer sheath 70 is also not particularly limited to the above. For example, multiple tension members may be arranged at equal intervals along the circumferential direction of the optical fiber cable 1.

[0050] In this embodiment, the X-axis in FIG. 1 passes through the midpoint between the centers of the tension members 80A and 80B and the midpoint between the centers of the tension members 80C and 80D. Meanwhile, the Y-axis in FIG. 1 passes through the center of the ripcord 50A and the center of the ripcord 50B. Therefore, the opposing direction of the tension members 80A-80D (the X-direction in FIG. 1) is substantially perpendicular to the opposing direction of the ripcords 50A and 50B (the Y-direction in FIG. 1). By preventing the ripcords 50A and 50B from overlapping with the tension members 80A-80D in the circumferential direction of the optical fiber cable 1, the workability of the tearing operation can be improved. The ripcords 50A and 50B may be positioned within a ±45-degree range with respect to the direction (the Y-direction in FIG. 1) that is substantially perpendicular to the opposing direction of the tension members 80A-80D (the X-direction in FIG. 1).

[0051] Examples of materials constituting each of the tension members 80A-80D include non-metallic materials and metallic materials. Specific examples of non-metallic materials include, but are not limited to, fiber-reinforced plastics (FRPs) such as glass fiber reinforced plastic (GFRP), aramid fiber reinforced plastic (KFRP) reinforced with Kevlar (registered trademark), polyethylene fiber reinforced plastic (PEF), and carbon fiber reinforced plastic (CFRP) reinforced with carbon fiber. Specific examples of metallic materials include, but are not limited to, metal wires such as steel wires.

[0052] As will be described later, in this embodiment, when manufacturing the optical fiber cable 1, the reinforcing sheet 60 is pressed inward to plastically deform the cable main 10, thereby crushing and deforming the cable main 10 with the reinforcing sheet 60. Therefore, the reinforcing sheet 60 is in partial contact with the cable main 10 while maintaining the elastic deformation of the cable main 10 toward the inside of the cable main 10. That is, the cable main 10 is housed in the reinforcing sheet 60 while being compressed in the X direction (short axis direction) of FIG. 1 . Therefore, when the cable main 10 is removed from the reinforcing sheet 60, the cable main 10 is released from the elastic deformation, and the cross-sectional shape of the cable main 10 expands due to the elastic force. Note that the deformation that occurs in the cable main 10 when it is crushed may include inelastic (sustained) deformation in addition to the elastic deformation described above.

[0053] In other words, in a cross section perpendicular to the extension direction of the optical fiber cable 1 (the cross section shown in Figure 1, hereinafter also referred to simply as the "orthogonal cross section"), the cable main body 10 and the reinforcing sheet 60 are in contact at a first contact area of ​​the cable main body 10 and a second contact area of ​​the reinforcing sheet 60, and the cable main body 10 is covered by the reinforcing sheet 60 in a state in which it has a stress tending to expand in a direction from the first contact point included in the first contact portion toward the second contact point included in the second contact portion.

[0054] Although not particularly limited, specifically, the deformation rate (crushing rate) Cr of the cable main 10 after deformation relative to the cable main 10 in an unloaded state (before deformation) satisfies the following formula (4). When the deformation rate Cr is 4.1% or more, the workability of the tearing operation can be further improved. Furthermore, when the deformation rate Cr is 16.2% or less, the deterioration of the transmission characteristics of the optical fiber can be suppressed. Note that the deformation rate Cr may also satisfy the following formula (5): 4.1%≦Cr≦16.2% (4) 4.8%≦Cr≦13.7% (5)

[0055] The deformation ratio Cr is a value calculated by the following equations (6) and (7). ０１is the inner diameter of the inner sheath 30 before deformation (before being crushed), and D ０２ is the outer diameter of the inner sheath 30 before deformation, and D １１ is the minor axis of the inner diameter of the inner sheath 30 after deformation (after being crushed), and Ca is the deformation amount (crushed amount) of the cable main 10 relative to the cable main 10 before deformation. ０２ ×100... (6) Ca=D ０１ -D １１ … (7)

[0056] The circumferential length L or the cross-sectional area S of the deformed cable body 10 is measured by observing the cross section thereof, and the inner diameter D of the inner sheath 30 before deformation is calculated. ０１ , and the outer diameter D of the cable main body 10 before deformation ０２ may be estimated by converting it into a perfect circle using the following equations (8) and (9): In the following equations (8) and (9), D is the diameter of the circle, and the above D ０１ or D ０２ L = π × D ... (8) S = π × (D / 2) ２ … (9)

[0057] Although not particularly limited, specifically, the recovery rate Rr of the cable main 10 in an unloaded state (released) after deformation satisfies the following formula (10): 106%≦Rr≦131% (10).

[0058] The restoration rate Rr is a value calculated by the following formulas (11) to (13). １１ is the minor diameter of the inner diameter of the inner sheath 30 after deformation (after being crushed), and D １２ is the major axis of the inner diameter of the inner sheath 30 after deformation, and D ２１ is the minor diameter of the inner diameter of the inner sheath 30 after release (after removal from the reinforcing sheet 60), and D ２２ is the major axis of the inner diameter of the inner sheath 30 after release, and A １ is the aspect ratio of the inner diameter of the inner sheath 30 after deformation, and A ２ is the aspect ratio of the inner diameter of the inner sheath 30 after release. ２ / A １×100... (11) A １ =D １１ / D １２ … (12) A ２ =D ２１ / D ２２ … (13)

[0059] The unloaded state refers to a state in which no external load is being applied to the cable main 10. This unloaded state is, for example, a state in which no load other than its own weight is being applied to the cable main 10 before it is housed in the reinforcing sheet 60, or a state in which no load other than its own weight is being applied to the cable main 10 after it has been removed from the reinforcing sheet 60. More specifically, this unloaded state is, for example, a state in which no radial force is being applied to a cross section of the cable main 10 taken perpendicular to the longitudinal direction thereof, and also includes a state in which the cable main 10 is filled with an epoxy resin or the like to prevent deformation of the cable main 10.

[0060] Although not particularly limited, an imaginary line VL passing through the center 1a of the optical fiber cable 1 and the centers of the ripcords 50A and 50B １ and the direction of elastic deformation of the cable body 10 (the imaginary line VL in the figure). ２ ) preferably satisfies the following formula (14): 45°≦θ≦135° (14) In this embodiment, the intersection angle θ with the virtual straight line VL １ corresponds to the Y-axis in FIG. ２ 1 coincides with the X-axis in FIG. 1, and the Y-axis and X-axis intersect at the center 1a of the optical fiber cable 1 in FIG.

[0061] Because the reinforcing sheet 60 compresses the cable main 10 in the X direction (minor axis direction) in FIG. 1 , the reinforcing sheet 60 has an oval cross-sectional shape with an inner diameter Dsy along the major axis and an inner diameter Dsx along the minor axis (Dsy > Dsx). The cable main 10 also has an oval cross-sectional shape with an outer diameter Dcy along the major axis and an outer diameter Dcx along the minor axis (Dcy > Dcx). The major axes of the reinforcing sheet 60 and the cable main 10 coincide with the Y axis in FIG. 1 , and the minor axes of the reinforcing sheet 60 and the cable main 10 coincide with the X axis in FIG. 1. Note that, when the reinforcing sheet 60 has a corrugated shape, the above Dsy and Dsx are the inner diameters of the inner circumferential surface at the valleys of the corrugated shape and the inner diameters of the inner circumferential surface at the apexes of the portions that protrude convexly toward the inside in the radial direction of the optical fiber cable 1.

[0062] The inner diameter Dsy of the major axis of the reinforcing sheet 60 is wider than the outer diameter Dcy of the major axis of the cable main 10 (Dsy > Dcy). On the other hand, the inner diameter Dsx of the minor axis of the reinforcing sheet 60 and the outer diameter Dcx of the minor axis of the cable main 10 are substantially the same (Dsx ≈ Dcx), and the inner surface of the reinforcing sheet 60 and the outer surface of the cable main 10 are in contact with each other at a portion 66 of the minor axis.

[0063] The ripcords 50A and 50B can be positioned within the space 65 by the inner diameter Dsx of the minor axis of the reinforcing sheet 60 satisfying the following formula (15). ０２ is the outer diameter of the inner sheath 30 having a circular cross-sectional shape before being crushed by the reinforcing sheet 60, Tw is the thickness of the holding winding tape 40, and Dr is the outer diameter of the ripcords 50A and 50B.

[0064] Dsx≦D ０２ +3×Tw+Dr…(15)

[0065] A pair of spaces 65 are formed between the outer peripheral surface of the cable main body 10 and the inner peripheral surface of the reinforcing sheet 60, separated by a contact portion 66 between the cable main body 10 and the reinforcing sheet 60. As described above, since the cable main body 10 is compressed in the X direction (short axis direction) in Fig. 1, each space 65 has a crescent-shaped cross section. The distance L of each space 65 along the radial direction of the optical fiber cable 1 is １ is maximum on the major axis, but this distance L １ is equal to or smaller than the outer diameter Dr of the ripcords 50A and 50B (L １ ≦Dr).

[0066] In this way, in this embodiment, the reinforcing sheet 60 is in partial contact with the cable main body 10 while maintaining the elastic deformation of the cable main body 10 toward the inside of the cable main body 10, so that the movement of the ripcords 50A, 50B between the cable main body 10 and the reinforcing sheet 60 can be limited within a certain range.

[0067] In this embodiment, the distance L of the space formed between the cable main 10 and the reinforcing sheet 60 １ is equal to or less than the outer diameter Dr of the ripcords 50A and 50B (L １ ≦Dr). This further prevents the ripcords 50A, 50B from moving in the circumferential direction of the optical fiber cable 1 between the cable main 10 and the reinforcing sheet 60.

[0068] Although not particularly limited, in the orthogonal cross section of the optical fiber cable 1, an area of ​​more than 20% but less than 95% of the outer circumferential surface of the cable main 10 is not in contact with the inner circumferential surface of the reinforcing sheet 60. In other words, in the orthogonal cross section of the optical fiber cable 1, an area of ​​5% or more but 80% or less of the outer circumferential surface of the cable main 10 is in contact with the inner circumferential surface of the reinforcing sheet 60. Therefore, in the orthogonal cross section of the optical fiber cable 1, the sum S of the lengths of the pair of contact portions 66 along the outer circumferential surface of the cable main 10 is １ is the total length L of the outer circumferential surface of the cable main body 10 ２ are 5% or more and 80% or less (L ２ ×5%≦S １ ≦L ２×80%).

[0069] By bringing the outer peripheral surface of the cable main body 10 and the inner peripheral surface of the reinforcing sheet 60 into partial contact in this manner, the ripcords 50A, 50B can be placed in a localized space 65 between the cable main body 10 and the reinforcing sheet 60 without forming the above-mentioned grooves in the inner peripheral surface of the reinforcing sheet 60 or the outer peripheral surface of the cable main body 10. Furthermore, as will be described later, because no grooves for accommodating the ripcords are formed in the reinforcing sheet 60 or the cable main body 10, the circumferential movement of the ripcords 50A, 50B can be limited within a certain range while maintaining the design freedom and reliability of the optical fiber cable 1.

[0070] In this embodiment, both the reinforcing sheet 60 and the cable main body 10 have an oval cross-sectional shape, but as long as the reinforcing sheet 60 and the cable main body 10 are in partial contact with each other and a space 65 is formed between the reinforcing sheet 60 and the cable main body 10, the cross-sectional shapes of the reinforcing sheet 60 and the cable main body 10 are not particularly limited to the above.

[0071] For example, the reinforcing sheet 60 may have a circular cross-sectional shape, and the cable main 10 may have an oval cross-sectional shape. Alternatively, the reinforcing sheet 60 may have an oval cross-sectional shape, and the cable main 10 may have a circular cross-sectional shape. Note that the above-mentioned oval shape includes not only a mathematical ellipse, but also an oval (a shape formed by connecting two semicircles with a pair of straight lines), a polygon with arc-shaped corners, and the like.

[0072] Alternatively, the cross-sectional shape of the reinforcing sheet 60 may be a non-circular shape other than an ellipse, and in this case, the "minor axis" refers to the shortest linear axis that passes through the center 1a of the optical fiber cable 1 in the cross-sectional shape of the reinforcing sheet 60. Similarly, the cross-sectional shape of the cable main 10 may be a non-circular shape other than an ellipse, and in this case, the "minor axis" refers to the shortest linear axis that passes through the center 1a of the optical fiber cable 1 in the cross-sectional shape of the cable main 10.

[0073] The inner peripheral surface of the outer sheath 70 also has an elliptical cross-sectional shape corresponding to the cross-sectional shape of the reinforcing sheet 60. On the other hand, the outer peripheral surface of the outer sheath 70 has a circular cross-sectional shape. Therefore, the thickness Ty of the portion of the outer sheath 70 corresponding to the major axis of the cross-sectional shape of the reinforcing sheet 60 is thinner than the thickness Tx of the portion of the outer sheath 70 corresponding to the minor axis of the cross-sectional shape of the reinforcing sheet 60 (Ty<Tx).

[0074] The thickness Ty of the portion of the outer sheath 70 corresponding to the major axis of the cross-sectional shape of the reinforcing sheet 60 is thinner (Ty<Ta) than the thickness Ta (not shown) of the other portion of the outer sheath 70. This allows the thinnest portion of the outer sheath 70 to face the ripcords 50A, 50B, improving the workability of the tearing operation.

[0075] Furthermore, the thickness Tx of the portion of the outer sheath 70 corresponding to the minor axis of the cross-sectional shape of the reinforcing sheet 60 is thicker (Tx>Tb) than the thickness Tb (not shown) of the other portion of the outer sheath 70. This allows the tension members 80A to 80D to be arranged only in the portion of the outer sheath 70 corresponding to the minor axis of the cross-sectional shape of the reinforcing sheet 60. Note that the thicknesses Tx, Ty, Ta, and Tb of the outer sheath 70 described above are thicknesses of the outer sheath 70 along the radial direction of the optical fiber cable 1.

[0076] The optical fiber cable 1 does not necessarily have to include the reinforcing sheet 60. In this case, a space 65 is formed between the inner peripheral surface of the outer sheath 70 and the outer peripheral surface of the cable main body 10, and the outer sheath 70 is in partial contact with the cable main body 10 while maintaining elastic deformation of the cable main body 10 toward the inside of the cable main body 10.

[0077] Alternatively, the optical fiber cable 1 may not be provided with the holding winding tape 40. In this case, a space 65 is formed between the inner peripheral surface of the reinforcing sheet 60 and the outer peripheral surface of the inner sheath 30, and the reinforcing sheet 60 is in partial contact with the inner sheath 30 while maintaining the elastic deformation of the cable main 10 toward the inside of the cable main 10.

[0078] Alternatively, the optical fiber cable 1 may not include the holding winding tape 40 and the reinforcing sheet 60. In this case, a space 65 is formed between the inner peripheral surface of the outer sheath 70 and the outer peripheral surface of the inner sheath 30, and the outer sheath 70 is in partial contact with the inner sheath 30 while maintaining elastic deformation of the cable main 10 toward the inside of the cable main 10.

[0079] Furthermore, since the thickness Tx of the portion of the outer sheath 70 corresponding to the minor axis of the cross-sectional shape of its inner surface is thicker than the thickness Tb (not shown) of other portions of the outer sheath 70 (Tx > Tb), the outer sheath 70 makes it easier to maintain the elastic deformation of the cable main body 10 even if the optical fiber cable 1 does not have a reinforcing tape 60.

[0080] A method for manufacturing the optical fiber cable 1 according to this embodiment will be described below with reference to Fig. 2. Fig. 2 is a diagram showing a manufacturing apparatus 100 for manufacturing the optical fiber cable 1 according to the embodiment of the present invention.

[0081] The manufacturing apparatus 100 for manufacturing the optical fiber cable 1 includes a molding machine 110, a pressing machine 120, and an extruder 130.

[0082] The molding machine 110 is continuously supplied with the optical fiber assemblage 20 covered with the inner sheath 30, the holding and winding tape 40, the ripcords 50A and 50B, and the reinforcing sheet 60 from respective supply devices.

[0083] The molding machine 110 is equipped with a die that guides the holding winding tape 40 and the ripcords 50A, 50B. Using this die, the molding machine 110 feeds the optical fiber assembly 20 covered with the inner sheath 30, and forms the cable main 10 by longitudinally attaching the holding winding tape 40 to the inner sheath 30, while also arranging the ripcords 50A, 50B along the outer periphery of the cable main 10.

[0084] The molding machine 110 also includes a molding guide that forms the reinforcing sheet 60 into a cylindrical shape. Using this molding guide, the molding machine 110 forms the reinforcing sheet 60 into a cylindrical shape while covering the outer periphery of the cable main 10 to which the ripcords 50A and 50B are attached with the reinforcing sheet 60.

[0085] The pressing machine 120 is equipped with a pair of pressure rollers 121 that press and deform the reinforcing sheet 60. The cable main 10 covered with the reinforcing sheet 60 is supplied from the molding machine 110, and the cable main 10 covered with the reinforcing sheet 60 is passed between the pressure rollers 121. During this passage, the reinforcing sheet 60 is pressed by the pressure rollers 121, and the cross-sectional shape of the reinforcing sheet 60 is deformed from a circular shape to an elliptical shape. Furthermore, the cable main 10 is also crushed in accordance with the deformation of the reinforcing sheet 60, and the cross-sectional shape of the cable main 10 is also deformed from a circular shape to an elliptical shape.

[0086] At this time, because the deformation of the reinforcing sheet 60 is plastic, the cable main 10 is housed in the reinforcing sheet 60 while maintaining its elastic deformation. The pressure roller 121 presses the reinforcing sheet 60 in a direction (indicated by the left and right thick arrows in FIG. 1 ) that does not overlap with the ripcords 50A, 50B in the radial direction of the optical fiber cable 1. In this embodiment, the pressure roller 121 presses the reinforcing sheet 60 from opposite directions toward the center 1a of the optical fiber cable 1. This forms a pair of spaces 65 separated by a contact portion 66 between the cable main 10 and the reinforcing sheet 60. The ripcords 50A, 50B can be housed in the pair of spaces 65, so that movement of the ripcords 50A, 50B along the circumferential direction of the optical fiber cable 1 can be limited within a certain range.

[0087] When deforming the reinforcing sheet 60, the ripcords 50A and 50B can be positioned within the space 65 by pressing the reinforcing sheet 60 with the pressure roller 121 so as to satisfy the following formula (16): Ddx is the distance of the portion of the space between the pair of pressure rollers 121 that corresponds to the minor axis of the reinforcing sheet 60 after deformation, and D ０２is the outer diameter of the inner sheath 30 having a circular cross-sectional shape before being crushed by the reinforcing sheet 60, Tw is the thickness of the holding winding tape 40, Ts is the thickness of the reinforcing sheet 60, and Dr is the outer diameter of the ripcords 50A and 50B.

[0088] Ddx≦D ０２ +3×Tw+3×Ts+Dr…(16)

[0089] Furthermore, the structure of the pressing machine 120 is not particularly limited to the above, as long as it has the function of pressing and deforming the reinforcing sheet 60. For example, the pressing machine 120 may be equipped with a die that presses and deforms the reinforcing sheet 60. In this case, Ddx in the above formula (16) is the minor diameter of the die hole of the die.

[0090] The reinforcing sheet 60 and the cable main 10 that have been crushed by the press machine 120 are supplied to the extruder 130. The extruder 130 guides the cable main 10 covered with the reinforcing sheet 60 into a die hole using a nipple, and extrudes the molten resin filled in the die from the die hole onto the outer periphery of the reinforcing sheet 60, thereby forming an outer sheath 70 having a circular cross-sectional shape.

[0091] As described above, in this embodiment, the reinforcing sheet 60 is in partial contact with the cable main body 10 while maintaining the elastic deformation of the cable main body 10 toward the inside of the cable main body 10, so that the movement of the rip cords 50A, 50B along the circumferential direction of the optical fiber cable 1 can be limited within a certain range, thereby improving the workability of the tearing operation.

[0092] In this embodiment, the distance L of the space 65 formed between the cable main body 10 and the reinforcing sheet 60 along the radial direction of the optical fiber cable 1 is １ is equal to or less than the outer diameter Dr of the ripcords 50A and 50B (L １ ≦Dr), the movement of the ripcords 50A, 50B along the circumferential direction of the optical fiber cable 1 can be further suppressed, and the workability of the tearing operation can be further improved.

[0093] Furthermore, if grooves for accommodating ripcords are formed in the reinforcing sheet or the cable body, these grooves may limit the design of the optical fiber cable 1. In contrast, in this embodiment, grooves for accommodating ripcords 50A, 50B are not formed in the reinforcing sheet 60 or the cable body 10, so that the degree of freedom in the design of the optical fiber cable 1 is maintained while the circumferential movement of the ripcords 50A, 50B can be limited within a certain range.

[0094] Furthermore, if grooves for accommodating ripcords are formed in the reinforcing sheet or the cable body, stress may be concentrated in the grooves, which may affect the reliability of the optical fiber cable. In contrast, in this embodiment, grooves for accommodating ripcords 50A, 50B are not formed in the reinforcing sheet 60 or the cable body 10, so the circumferential movement of ripcords 50A, 50B can be limited within a certain range while maintaining the reliability of the optical fiber cable 1.

[0095] Furthermore, in this embodiment, when manufacturing the optical fiber cable 1, the ripcords 50A, 50B can be constrained in the space 65 formed between the cable body 10 and the reinforcing sheet 60 simply by pressing and deforming the cable body 10, so that an optical fiber cable 1 can be easily manufactured in which the movement of the ripcords 50A, 50B is limited within a certain range.

[0096] It should be noted that the above-described embodiments have been described to facilitate understanding of the present invention, and are not intended to limit the present invention. Therefore, the elements disclosed in the above embodiments are intended to include all design modifications and equivalents that fall within the technical scope of the present invention.

[0097] For example, in the above-described embodiment, the ripcords 50A, 50B and the direction of elastic deformation of the cable main body 10 do not overlap in the circumferential direction of the optical fiber cable 1, but the positional relationship between the ripcords 50A, 50B and the direction of elastic deformation is not particularly limited to this.

[0098] For example, as shown in Fig. 3, the direction of elastic deformation of the ripcords 50A and 50B and the direction of elastic deformation of the cable main body 10 (the direction of the thick arrows in Fig. 3) may overlap in the circumferential direction of the optical fiber cable 1. That is, an imaginary line VL passing through the center 1a of the fiber cable 1 and the centers of the ripcords 50A and 50B １ and the direction of elastic deformation of the cable main 10 (the virtual line VL in FIG. 3 ). ２ 3 is a cross-sectional view showing an optical fiber cable according to another embodiment of the present invention.

[0099] In this way, the reinforcing sheet 60 is in partial contact with the cable main 10 while maintaining the elastic deformation of the cable main 10 toward the inside of the cable main 10, thereby allowing the distance between the ripcords 50A, 50B to be kept constant due to the elastic deformation of the cable main 10. This allows the movement of the ripcords 50A, 50B along the circumferential direction of the optical fiber cable 1 to be limited within a certain range, improving the workability of the tearing operation. Note that, although the inner circumferential surface of the reinforcing sheet 60 and the outer circumferential surface of the cable main 10 are in contact along their major axes in the example shown in Fig. 3, the reinforcing sheet 60 and the cable main 10 may have cross-sectional shapes such that the inner circumferential surface of the reinforcing sheet 60 and the outer circumferential surface of the cable main 10 are in contact along their minor axes. In addition, in the example shown in Figure 3, the thickness of the portion of the outer sheath 70 corresponding to the long axis of the cross-sectional shape of the reinforcing sheet 60 is thinner than the thickness of other portions of the outer sheath 70, but the thickness of the portion of the outer sheath 70 corresponding to the long axis of the cross-sectional shape of the reinforcing sheet 60 may also be thicker than the thickness of other portions of the outer sheath 70.

[0100] Furthermore, in the above-described embodiment, after the reinforcing sheet 60 is formed into a cylindrical shape by the molding machine 110, the reinforcing sheet 60 is pressed and deformed by a pair of pressure rollers provided in a pressing machine 120 separate from the molding machine 110, but the timing of pressing and deforming the reinforcing sheet 60 is not particularly limited to this. For example, the guide of the molding machine 110 may have a function to press and deform the reinforcing sheet 60 in addition to the function to form the reinforcing sheet 60 into a cylindrical shape. In this case, the forming of the reinforcing sheet 60 into a cylindrical shape and the pressing and deformation of the reinforcing sheet 60 are performed almost simultaneously.

[0101] Furthermore, when the optical fiber cable 1 does not include the reinforcing sheet 60, for example, the outer periphery of the cable main 10 to which the ripcords 50A and 50B are attached is covered with the outer sheath 70 by the extruder 130 shown in Fig. 2, and then, before the outer sheath 70 hardens, the outer sheath 70 is pressed and deformed by a pair of pressure rollers to crush the cable main 10. Alternatively, the cable main 10 may be crushed with a nipple during the extrusion molding of the outer sheath 70. In this case, the extrusion molding of the outer sheath 70 and the pressing and deformation of the cable main 10 are carried out almost simultaneously.

[0102] Examples and comparative examples of this embodiment are described below. In the following examples and comparative examples, optical fiber cables were fabricated and the transmission characteristics and tearability of the optical fiber cables were evaluated. Note that the present invention is not limited to these examples.

[0103] In Examples A1 to A7, optical fiber cables were fabricated using optical fiber ribbons and having a 144-fiber cable main body as shown in Fig. 1. The optical fibers constituting the cable main body were optical fibers having a diameter of 250 µm.

[0104] In Examples A1 to A7, the reinforcing sheet was pressed by a pressure roller to deform the cable body from a perfect circle to an ellipse. １The pressure roller was adjusted so that the values ​​of (see formula (12) above) were 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, and 0.95. As a result of this adjustment, the deformation amount Ca (see formula (7) above) and deformation rate Cr (see formula (6) above) of the cable bodies of Examples A1 to A7 became the values ​​shown in Table 1 below.

[0105] Thereafter, for each of Examples A1 to A7, the cable main body was removed from the deformed reinforcing sheet, and the dimensions of the cross section of the cable main body were measured. Based on these dimensions, the aspect ratio A of the inner diameter of the released inner sheath of Examples A1 to A7 was calculated. ２ (see formula (13) above) and the recovery rates Rr (see formula (11) above) of the cable bodies of Examples A1 to A7 were calculated, and the results are shown in Table 1 below.

[0106] <Comparative Example A1> In Comparative Example A1, the reinforcing sheet and the cable body were not deformed (i.e., the aspect ratio A １ The deformation amount Ca, deformation rate Cr, aspect ratio A of Comparative Example A1 were calculated as follows: ２ , and the recovery rate Rr were the values ​​shown in Table 1 below.

[0107]

[0108] <Examples B1 to B7> In Examples B1 to B7, optical fiber cables as shown in FIG. 1 were fabricated, each having a cable main body with 288 fibers using an optical fiber ribbon. The optical fiber constituting the cable main body was an optical fiber having a diameter of 250 μm. In Examples B1 to B7, the cable main body was also deformed from a perfect circle to an ellipse. In this case, the aspect ratio A of each of Examples B1 to B7 was １ The pressure of the pressure roller was adjusted so that the values ​​of Ca, Cr, and Aspect Ratio A were 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, and 0.95. ２ , and the recovery rate Rr were the values ​​shown in Table 2 below.

[0109] <Comparative Example B1> In Comparative Example B1, an optical fiber cable having the same configuration as in Examples B1 to B7 was produced, except that the reinforcing sheet and the cable body were not deformed. The deformation amount Ca, deformation rate Cr, and aspect ratio A of Comparative Example B1 were ２ , and the recovery rate Rr were the values ​​shown in Table 2 below.

[0110]

[0111] Examples C1 to C7 In Examples C1 to C7, optical fiber cables as shown in FIG. 1 were fabricated, each having a cable main body with 864 fibers using an optical fiber ribbon. The optical fiber constituting the cable main body was an optical fiber having a diameter of 250 μm. In Examples C1 to C7, the cable main body was also deformed from a perfect circle to an ellipse. In this case, the aspect ratio A of each of Examples C1 to C7 was １ The pressure of the pressure roller was adjusted so that the values ​​of Ca, Cr, Aspect ratio A were 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, and 0.95. ２ , and the recovery rate Rr were the values ​​shown in Table 3 below.

[0112] Comparative Example C1 In Comparative Example C1, an optical fiber cable was produced having the same configuration as in Examples C1 to C7 described above, except that the reinforcing sheet and the cable body were not deformed. The deformation amount Ca, deformation rate Cr, and aspect ratio A of Comparative Example C1 were ２ , and the recovery rate Rr were the values ​​shown in Table 3 below.

[0113]

[0114] Examples D1 to D7 In Examples D1 to D7, optical fiber cables as shown in FIG. 1 were fabricated, each having a cable main body with 144 fibers using an optical fiber ribbon. The optical fiber constituting the cable main body was an optical fiber having a diameter of 200 μm. In Examples D1 to D7, the cable main body was also deformed from a perfect circle to an ellipse. In this case, the aspect ratio A of each of Examples D1 to D7 was １The pressure of the pressure roller was adjusted so that the values ​​of Ca, Cr, and Aspect Ratio A were 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, and 0.95. ２ , and the recovery rate Rr were the values ​​shown in Table 4 below.

[0115] <Comparative Example D1> In Comparative Example D1, an optical fiber cable having the same configuration as in Examples D1 to D7 was produced, except that the reinforcing sheet and the cable body were not deformed. The deformation amount Ca, deformation rate Cr, and aspect ratio A of Comparative Example D1 were ２ , and the recovery rate Rr were the values ​​shown in Table 4 below.

[0116]

[0117] Examples E1 to E7 In Examples E1 to E7, optical fiber cables as shown in FIG. 1 were fabricated, each having a cable main body with 864 fibers using an optical fiber ribbon. The optical fiber constituting the cable main body was an optical fiber having a diameter of 200 μm. In Examples E1 to E7, the cable main body was also deformed from a perfect circle to an ellipse. In this case, the aspect ratio A of each of Examples E1 to E7 was １ The pressure of the pressure roller was adjusted so that the values ​​of Ca, Cr, Aspect ratio A were 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, and 0.95. ２ , and the recovery rate Rr were the values ​​shown in Table 5 below.

[0118] Comparative Example E1 In Comparative Example E1, an optical fiber cable was produced having the same configuration as in Examples E1 to E7, except that the reinforcing sheet and the cable body were not deformed. The deformation amount Ca, deformation rate Cr, and aspect ratio A of Comparative Example E1 were ２ , and the recovery rate Rr were the values ​​shown in Table 5 below.

[0119]

[0120] <Examples F1 to F7> In Examples F1 to F7, optical fiber cables as shown in FIG. 1 were fabricated, each having a cable main body with 1,728 fibers using an optical fiber ribbon. The optical fiber constituting the cable main body was an optical fiber having a diameter of 200 μm. In Examples F1 to F7, the cable main body was also deformed from a perfect circle to an ellipse. In this case, the aspect ratio A of each of Examples F1 to F7 was １ The pressure of the pressure roller was adjusted so that the values ​​of Ca, Cr, Aspect Ratio A were 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, and 0.95. ２ , and the recovery rate Rr were the values ​​shown in Table 6 below.

[0121] Comparative Example F1 In Comparative Example F1, an optical fiber cable was produced having the same configuration as the above-described Examples F1 to F7, except that the reinforcing sheet and the cable body were not deformed. The deformation amount Ca, deformation rate Cr, and aspect ratio A of Comparative Example F1 were ２ , and the recovery rate Rr were the values ​​shown in Table 6 below.

[0122]

[0123] Examples G1 to G7 In Examples G1 to G7, optical fiber cables as shown in FIG. 1 were fabricated, each having a cable main body with 144 fibers using an optical fiber ribbon. The optical fiber constituting the cable main body was an optical fiber having a diameter of 160 μm. In Examples G1 to G7, the cable main body was also deformed from a perfect circle to an ellipse. In this case, the aspect ratio A of each of Examples G1 to G7 was １ The pressure of the pressure roller was adjusted so that the values ​​of Ca, Cr, and Aspect Ratio A were 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, and 0.95. ２ , and the recovery rate Rr were the values ​​shown in Table 7 below.

[0124] <Comparative Example G1> In Comparative Example G1, an optical fiber cable having the same configuration as in Examples G1 to G7 was produced, except that the reinforcing sheet and the cable body were not deformed. The deformation amount Ca, deformation rate Cr, and aspect ratio A of Comparative Example G1 were２ , and the recovery rate Rr were the values ​​shown in Table 7 below.

[0125]

[0126] <Examples H1 to H7> In Examples H1 to H7, optical fiber cables as shown in FIG. 1 were fabricated, each having a cable main body with 288 fibers using an optical fiber ribbon. The optical fiber constituting the cable main body was an optical fiber having a diameter of 160 μm. In Examples H1 to H7, the cable main body was also deformed from a perfect circle to an ellipse. In this case, the aspect ratio A of each of Examples H1 to H7 was １ The pressure of the pressure roller was adjusted so that the values ​​of Ca, Cr, and Aspect Ratio A of Examples H1 to H7 were 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, and 0.95. ２ , and the recovery rate Rr were the values ​​shown in Table 8 below.

[0127] Comparative Example H1 In Comparative Example H1, an optical fiber cable was produced having the same configuration as in Examples H1 to H7 described above, except that the reinforcing sheet and the cable body were not deformed. The deformation amount Ca, deformation rate Cr, and aspect ratio A of Comparative Example H1 were ２ , and the recovery rate Rr were the values ​​shown in Table 8 below.

[0128]

[0129] <Examples I1 to I7> In Examples I1 to I7, optical fiber cables as shown in FIG. 1 were fabricated, each having a cable main body with 864 fibers using an optical fiber ribbon. The optical fiber constituting the cable main body was an optical fiber having a diameter of 160 μm. In Examples I1 to I7, the cable main body was also deformed from a perfect circle to an ellipse. In this case, the aspect ratio A of each of Examples I1 to I7 was １ The pressure of the pressure roller was adjusted so that the values ​​of Ca, Cr, Aspect ratio A were 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, and 0.95. ２ , and the recovery rate Rr were the values ​​shown in Table 9 below.

[0130] Comparative Example I1 In Comparative Example I1, an optical fiber cable was produced having the same configuration as in Examples I1 to I7 described above, except that the reinforcing sheet and the cable body were not deformed. The deformation amount Ca, deformation rate Cr, and aspect ratio A of Comparative Example I1 were ２ , and the recovery rate Rr were the values ​​shown in Table 9 below.

[0131]

[0132] Examples J1 to J7 In Examples J1 to J7, optical fiber cables as shown in FIG. 1 were fabricated, each having a cable main body with 1,728 fibers using an optical fiber ribbon. The optical fiber constituting the cable main body was an optical fiber having a diameter of 160 μm. In Examples J1 to J7, the cable main body was also deformed from a perfect circle to an ellipse. In this case, the aspect ratio A of each of Examples J1 to J7 was １ The pressure of the pressure roller was adjusted so that the values ​​of Ca, Cr, Aspect ratio A were 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, and 0.95. ２ , and the recovery rate Rr were the values ​​shown in Table 10 below.

[0133] Comparative Example J1 In Comparative Example J1, an optical fiber cable was produced having the same configuration as the above-described Examples J1 to J7, except that the reinforcing sheet and the cable body were not deformed. The deformation amount Ca, deformation rate Cr, and aspect ratio A of Comparative Example J1 were ２ , and the recovery rate Rr were the values ​​shown in Table 10 below.

[0134]

[0135] <Examples K1 to K7> In Examples K1 to K7, optical fiber cables as shown in FIG. 1 were fabricated, each having a 144-fiber cable main body using optical fiber strands instead of an optical fiber ribbon. An optical fiber having a diameter of 250 μm was used as the optical fiber constituting the cable main body. In Examples K1 to K7, the cable main body was also deformed from a perfect circle to an ellipse. In this case, the aspect ratio A of each of Examples K1 to K7 was １The pressure of the pressure roller was adjusted so that the values ​​of Ca, Cr, Aspect ratio A were 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, and 0.95. ２ , and the recovery rate Rr were the values ​​shown in Table 11 below.

[0136] <Comparative Example K1> In Comparative Example K1, an optical fiber cable having the same configuration as the above-mentioned Examples K1 to K7 was produced, except that the reinforcing sheet and the cable body were not deformed. The deformation amount Ca, deformation rate Cr, and aspect ratio A of Comparative Example K1 were ２ , and the recovery rate Rr were the values ​​shown in Table 11 below.

[0137]

[0138] <Examples L1 to L7> In Examples L1 to L7, optical fiber cables as shown in FIG. 1 were fabricated, each having a 288-fiber cable main body using optical fiber strands instead of an optical fiber ribbon. An optical fiber having a diameter of 250 μm was used as the optical fiber constituting the cable main body. In Examples L1 to L7, the cable main body was also deformed from a perfect circle to an ellipse. In this case, the aspect ratio A of each of Examples L1 to L7 was １ The pressure of the pressure roller was adjusted so that the values ​​of Ca, Cr, Aspect ratio A of Examples L1 to L7 were 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, and 0.95. ２ , and the recovery rate Rr were the values ​​shown in Table 12 below.

[0139] Comparative Example L1 In Comparative Example L1, an optical fiber cable was produced having the same configuration as Examples L1 to L7 described above, except that the reinforcing sheet and the cable body were not deformed. The deformation amount Ca, deformation rate Cr, and aspect ratio A of Comparative Example L1 were ２ , and the recovery rate Rr were the values ​​shown in Table 12 below.

[0140]

[0141] <Examples M1 to M7> In Examples M1 to M7, optical fiber cables as shown in FIG. 1 were fabricated, each having a cable main body with 864 fibers, using optical fiber strands instead of an optical fiber ribbon. The optical fiber constituting the cable main body was an optical fiber having a diameter of 250 μm. In Examples M1 to M7, the cable main body was also deformed from a perfect circle to an ellipse. In this case, the aspect ratio A of each of Examples M1 to M7 was １ The pressure of the pressure roller was adjusted so that the values ​​of Ca, Cr, and Aspect Ratio A of Examples M1 to M7 were 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, and 0.95. ２ , and the recovery rate Rr were the values ​​shown in Table 13 below.

[0142] Comparative Example M1 In Comparative Example M1, an optical fiber cable having the same configuration as the above-described Examples M1 to M7 was produced, except that the reinforcing sheet and the cable body were not deformed. The deformation amount Ca, deformation rate Cr, and aspect ratio A of Comparative Example M1 were ２ , and the recovery rate Rr were the values ​​shown in Table 13 below.

[0143]

[0144] <Evaluation of Transmission Characteristics> The transmission characteristics of Examples A1 to M7 and Comparative Examples A1 to M1 were evaluated. In this evaluation, the optical fiber cables of Examples A1 to M7 and Comparative Examples A1 to M1 were subjected to two temperature cycles in the range of -40°C to +70°C, in accordance with the "Temperature Cycling" provisions of "Telcordia Technologies Generic Requirements GR-20-CORE, issue 4, July 2013," and the maximum attenuation fluctuations at a measurement wavelength of 1.55 μm were measured. In this transmission characteristic evaluation, if the maximum attenuation fluctuation was 0.15 dB / km or less, the results were evaluated as extremely good and given an "A." If the maximum attenuation fluctuation exceeded 0.15 dB / km but the results were satisfactory, the results were evaluated as "B." The results are shown in Tables 1 to 13.

[0145] In Examples A1 to M1, where the deformation ratio Cr of the deformed cable main body 10 relative to the undeformed cable main body 10 exceeded 16.2%, the maximum loss variation in this transmission characteristic evaluation exceeded 0.15 dB / km. This is thought to be due to the optical fiber being compressed by the crushing of the cable main body. Furthermore, in Examples A1 to M1, the recovery ratio Rr of the cable main body after release relative to the deformed cable main body exceeded 131%.

[0146] In contrast, in Examples A2 to M7 and Comparative Examples A1 to M1, where the deformation rate Cr was 16.2% or less, the maximum loss variation in the transmission characteristics evaluation was 0.15 dB / km or less. Furthermore, in Examples A2 to M7 and Comparative Examples A1 to M1, the recovery rate Rr was 131% or less. These results confirm that it is preferable for the deformation rate Cr to be 16.2% or less (Cr≦16.2%), and that it is preferable for the recovery rate to be 131% or less (Rr≦131%).

[0147] <Evaluation of Tearing Efficiency> Furthermore, for the above Examples A1 to M7 and Comparative Examples A1 to M1, the ease of tearing the reinforcement sheet and outer sheath using a ripcord was evaluated. In this tearing ease evaluation, if the tearing operation was performed smoothly, the result was evaluated as extremely good and rated as "A." If the tearing operation was performed after a short time, the result was evaluated as good and rated as "B." If the tearing operation took a long time, the result was evaluated as sufficient and rated as "C." If the tearing operation could not be performed, the result was evaluated as insufficient and rated as "D." The results are shown in Tables 1 to 13 above.

[0148] In Examples A7 to M7 and Comparative Examples A1 to M1, where the deformation ratio Cr of the deformed cable main body 10 relative to the undeformed cable main body 10 was less than 4.1%, the tearing workability was evaluated as "C" or "D." This is thought to be due to the ripcord moving between the cable main body and the reinforcing sheet. Furthermore, in Examples A7 to M7 and Comparative Examples A1 to M1, the recovery ratio Rr of the deformed cable main body after release relative to the undeformed cable main body was less than 106%.

[0149] In contrast, in Examples A1 to M6, in which the deformation rate Cr was 4.1% or more, the tearing workability was evaluated as "A" or "B." Furthermore, in Examples A1 to M6, the recovery rate Rr was 106% or more. From these results, it was confirmed that the deformation rate Cr is preferably 4.1% or more (Cr≧4.1%), and the recovery rate is preferably 106% or more (Rr≧106%).

[0150] DESCRIPTION OF SYMBOLS 1...Optical fiber cable 10...Cable body 20...Optical fiber assembly 21...Optical fiber 22...Pressure winding tape 23...Rip cord 30...Inner sheath 40...Pressure winding tape 50A, 50B...Rip cord 60...Reinforcing sheet 61...First end 62...Second end 63...Lapped portion 65...Space 70...Outer sheath 80A to 80D...Tension member 100...Manufacturing apparatus 110...Molding machine 120...Pressing machine 121...Pressure roller 130...Extruder

Claims

1. a cable body including an optical fiber; a protective layer that accommodates the cable body; a rip cord disposed in a space formed between the cable body and the protective layer, The protective layer is in partial contact with the cable body while maintaining elastic deformation of the cable body toward the inside of the cable body.

2. 2. The optical fiber cable according to claim 1, An optical fiber cable that satisfies the following formula (1). 45°≦θ≦135° … (1) In the above formula (1), θ is the angle of intersection between an imaginary line passing through the center of the optical fiber cable and the ripcord and the direction of the elastic deformation.

3. 3. The optical fiber cable according to claim 1, A fiber optic cable in which the radial distance of the fiber optic cable in the space is equal to or less than the outer diameter of the ripcord.

4. 2. The optical fiber cable according to claim 1, a radial distance of the optical fiber cable in the space is equal to or less than an outer diameter of the ripcord; An optical fiber cable in which the rip cord and the direction of the elastic deformation overlap in the circumferential direction of the optical fiber cable.

5. 3. The optical fiber cable according to claim 1, An optical fiber cable in which, in a cross section perpendicular to the extension direction of the optical fiber cable, a minor axis portion of the inner surface of the protective layer is in contact with a minor axis portion of the outer surface of the cable body.

6. 3. The optical fiber cable according to claim 1, The protective layer is a reinforcing sheet covering the outer periphery of the cable main body; a sheath covering the outer periphery of the reinforcing sheet, The reinforcing sheet is in partial contact with the cable body.

7. 7. The optical fiber cable according to claim 6, the reinforcing sheet has a lap portion where end portions of the reinforcing sheet overlap each other, The optical fiber cable, wherein the wrap portion and the ripcord are offset from each other in the circumferential direction of the optical fiber cable.

8. 3. The optical fiber cable according to claim 1, An optical fiber cable wherein the radial thickness of the protective layer at the contact portion with the cable main body is greater than the radial thickness of other portions of the protective layer.

9. 3. The optical fiber cable according to claim 1, An optical fiber cable in which the deformation rate Cr of the cable body relative to the cable body in an unloaded state satisfies the following formula (2). 4.1%≦Cr≦16.2% … (2)

10. 3. The optical fiber cable according to claim 1, An optical fiber cable in which the recovery rate Rr of the cable body when no load is applied to the cable body satisfies the following formula (3). 106%≦Rr≦131% … (3)

11. 3. The optical fiber cable according to claim 1, The protective layer has an inner surface on which no groove extending along the extending direction of the optical fiber cable is formed.

12. 3. The optical fiber cable according to claim 1, The cable body has an outer peripheral surface on which no grooves extending along the extending direction of the optical fiber cable are formed.

13. a first step of providing a cable body comprising an optical fiber; a second step of arranging a rip cord along an outer peripheral surface of the cable main body; a third step of housing the cable body and the ripcord in a protective layer and pressing and deforming the cable body.

14. 14. The method for manufacturing an optical fiber cable according to claim 13, The protective layer is a reinforcing sheet covering the outer periphery of the cable main body; a sheath covering the outer periphery of the reinforcing sheet, The third step is a method for manufacturing an optical fiber cable, which includes housing the cable body and the ripcord in the reinforcing sheet, and then deforming the cable body by pressing the reinforcing sheet in a direction radially of the optical fiber cable that does not overlap with the ripcord.