Optical fiber cable

Abstract

An optical fiber cable (1) comprises at least one coated optical fiber (10), a fiber-reinforced plastic (20) that encloses the coated optical fiber, and a sheath (30) that covers the fiber-reinforced plastic from the outside. In cross-section, the coated optical fiber (10) is embedded in the fiber-reinforced plastic (20).

Description

fiber optic cable

[0001] The present disclosure relates to fiber optic cables.

[0002] Patent Document 1 discloses a wire-pulling rod for pulling an additional optical fiber cable into an existing cable piping. 6 kg / mm 2 5.5 x 10 6 kg / mm 2 Since the wire-pulling rod is less likely to undulate inside the piping, the wire-pulling rod can be easily inserted.

[0003] Patent Document 2 discloses an optical fiber for a strain sensor that is installed in an object to be measured and measures the strain of the object to be measured. The optical fiber for a strain sensor has a plurality of holes in a cladding provided around a core. A first coating layer made of polyimide is formed on the outer periphery of the optical fiber for a strain sensor, and a second coating layer made of fiber-reinforced plastic is formed on the outer periphery of the first coating layer. Note that Patent Document 2 does not relate to optical fibers for communication purposes.

[0004] Japanese Patent Publication No. 2002-044822 Japanese Patent Publication No. 2005-337545

[0005] An optical fiber cable according to one aspect of the present disclosure comprises at least one optical fiber core, a fiber-reinforced plastic that contains the optical fiber core, and an outer jacket that covers the fiber-reinforced plastic from the outside, and in cross-sectional view, the optical fiber core is embedded in the fiber-reinforced plastic.

[0006] Fig. 1 is a cross-sectional view perpendicular to the longitudinal direction of an optical fiber cable according to a first embodiment. Fig. 2 is a cross-sectional view perpendicular to the longitudinal direction of an optical fiber cable according to a first modification. Fig. 3 is a cross-sectional view perpendicular to the longitudinal direction of an optical fiber cable according to a second modification.

[0007] [Problem to be Solved by the Present Disclosure] In recent years, the increase in the amount of information communicated has led to a demand for increased communication capacity and communication speed for optical fiber cables, which has led to an increase in the number of optical fiber cores housed in a single optical fiber cable.

[0008] In order to increase the number of optical fiber cores that can be housed, it is possible to increase the outer diameter of the optical fiber cable. However, this is limited by the diameter of the pipe through which the cable is to be laid. Furthermore, there is a demand for an optical fiber cable that can be installed as an additional cable even when an existing cable is installed in the pipe.

[0009] An object of the present disclosure is to provide an optical fiber cable for communication that has an increased core density and is also excellent in terms of ease of routing through existing cable piping.

[0010] (Description of an embodiment of the present disclosure) First, embodiments of the present disclosure will be listed and described. (1) An optical fiber cable according to an embodiment of the present disclosure includes at least one optical fiber, a fiber-reinforced plastic that encases the optical fiber, and an outer jacket that covers the fiber-reinforced plastic from the outside, and in a cross-sectional view, the optical fiber is embedded in the fiber-reinforced plastic.

[0011] According to the present disclosure, the fiber-reinforced plastic encapsulates the optical fiber core. Therefore, compared to a typical optical fiber cable in which the optical fiber core and the fiber-reinforced plastic are separately provided, space can be saved and the overall diameter of the optical fiber cable can be easily reduced. Furthermore, because the bending rigidity of the optical fiber cable can be maintained, even if other cables are already installed in the pipe, the optical fiber cable of the present disclosure can be easily installed in the pipe.

[0012] (2) In the above (1), the optical fiber may be a multi-core fiber.

[0013] According to the present disclosure, since the optical fiber core is a multi-core fiber, the core density of the optical fiber cable can be increased, and therefore, a communication optical fiber cable with a large communication capacity can be provided.

[0014] (3) In the above (1), the optical fiber may be a single-core fiber, and the optical fiber cable may include a plurality of the optical fiber.

[0015] According to the present disclosure, the optical fiber cable includes a plurality of optical fiber cores that are single-core fibers, and therefore, it is possible to provide a communication optical fiber cable with an increased core density and a large communication capacity.

[0016] (4) In any one of (1) to (3) above, the optical fiber cable may have an outer diameter of 2 mm or less.

[0017] According to the present disclosure, the outer diameter of the optical fiber cable is small, at 2 mm or less, so even if other cables are already installed in the piping, it is easy to lay the optical fiber cable of the present disclosure in addition to the piping.

[0018] (5) In any one of the above (1) to (4), the optical fiber cable may include a plurality of the optical fiber core wires, and the plurality of optical fiber core wires may be twisted together.

[0019] According to the present disclosure, since a plurality of optical fiber core wires are twisted together, the bending rigidity of the optical fiber cable can be increased compared to a case where a plurality of optical fiber core wires are not twisted together, and therefore, even if the optical fiber cable is bent inside a pipe, bending strain can be reduced.

[0020] Effect of the Present Disclosure According to the present disclosure, it is possible to provide an optical fiber cable for communication that has an increased core density and is also excellent in terms of ease of routing through existing cable piping.

[0021] (Details of an embodiment of the present disclosure) Specific examples of an optical fiber cable according to an embodiment of the present disclosure will be described with reference to the drawings. Note that the present disclosure is not limited to these examples, but is defined by the claims, and is intended to include all modifications within the meaning and scope of the claims.

[0022] First Embodiment An optical fiber cable 1 according to this embodiment will be described with reference to Fig. 1. Fig. 1 is a cross-sectional view perpendicular to the longitudinal direction of the optical fiber cable 1 according to the first embodiment.

[0023] As illustrated in Fig. 1, the optical fiber cable 1 includes at least one optical fiber core 10, a fiber-reinforced plastic 20, and an outer jacket 30. The optical fiber cable 1 is circular in cross section. The outer diameter of the optical fiber cable 1 is, for example, 2 mm or less. The optical fiber cable 1 of this embodiment is a slotless optical fiber cable and an optical cable for communication. The optical fiber cable 1 may be laid by being pushed into a pipe, or may be laid into the pipe by being compressed air fed into the pipe.

[0024] The optical fiber cable 1 of this embodiment includes a plurality of optical fiber cores 10. More specifically, twelve optical fiber cores 10 are arranged in the center portion of the optical fiber cable 1. Each optical fiber core 10 is circular in cross section. The outer diameter of each optical fiber core 10 is, for example, 200 μm or less.

[0025] In a cross-sectional view, the plurality of optical fiber cores 10 are arranged so as to be embedded in the fiber-reinforced plastic 20. Furthermore, the plurality of optical fiber cores 10 are arranged in a twisted manner. For example, the plurality of optical fiber cores 10 may be twisted in a spiral shape along the longitudinal direction of the optical fiber cable 1.

[0026] Each optical fiber 10 includes a glass fiber 11 as an optical transmission body and a coating resin layer 12 .

[0027] The glass fiber 11 is a glass member, for example, silica (SiO ２ The glass fiber 11 is formed of .gtoreq..125 μm glass. The glass fiber 11 is configured to transmit light introduced into the optical fiber core 10. The outer diameter of the glass fiber 11 is, for example, 125 μm.

[0028] The glass fiber 11 includes a plurality of cores 111 and a cladding 112 surrounding the cores 111. The cores 111 are provided, for example, in a region including the central portion of the glass fiber 11. The outer diameter (mode field diameter, MFD) of the cores 111 is, for example, 9 μm. The cores 111 are made of pure SiO ２ Glass or SiO ２ Glass with GeO ２ and fluorine element, etc., or SiO ２ Glass with GeO ２ Alternatively, it may contain fluorine element or the like.

[0029] The cladding 112 is provided in a region surrounding the cores 111. The refractive index of the cladding 112 is lower than that of the cores 111. The cladding 112 is made of pure SiO ２ It may be made of glass or SiO 2 to which fluorine elements are added. ２ It may be made of glass.

[0030] The optical fiber 10 of this embodiment is a multi-core fiber. In this embodiment, the glass fiber 11 includes four cores 111.

[0031] The coating resin layer 12 is a layer that covers the clad 112 and has ultraviolet curing properties. The coating resin layer 12 includes multiple layers. For example, the coating resin layer 12 has a primary resin layer and a secondary resin layer, both of which are formed from a urethane acrylate ultraviolet curing resin. The primary resin layer is in contact with the outer peripheral surface of the clad 112 and covers the entire clad 112. The secondary resin layer is in contact with the outer peripheral surface of the primary resin layer and covers the entire primary resin layer.

[0032] A colored layer may be provided on the outer periphery of the secondary resin layer. When the coating resin layer 12 has a colored layer, the colored layer is in contact with the outer periphery of the secondary resin layer and covers the entire secondary resin layer.

[0033] The fiber reinforced plastic 20 is configured to enclose a plurality of optical fiber cores 10. The fiber reinforced plastic 20 is circular in cross section. The outer diameter of the fiber reinforced plastic 20 is, for example, 1.2 mm. The fiber reinforced plastic 20 is formed, for example, as follows: A plurality of optical fiber cores 10 are arranged in the center, and aramid fibers are arranged around the plurality of optical fiber cores 10. Molten epoxy resin may be supplied so as to impregnate between the aramid fibers to form a mold, and then the epoxy resin, which is a thermosetting resin, may be cured to form the fiber reinforced plastic 20. The fibers used in the fiber reinforced plastic 20 may be resin fibers other than aramid, such as nylon, or may be glass fibers or carbon fibers.

[0034] The outer jacket 30 is configured to cover the fiber-reinforced plastic 20 from the outside. In a cross-sectional view, the thickness of the outer jacket 30 is, for example, 0.4 mm. The outer jacket 30 of this embodiment may be made of flame-retardant polyethylene with an oxygen index of 50 or higher. For example, the outer jacket 30 may contain a flame-retardant inorganic substance in polyethylene as a base resin. As the flame-retardant inorganic substance, the outer jacket 30 may contain, for example, magnesium hydroxide or aluminum hydroxide. The outer jacket 30 may contain a silicon-based lubricant to reduce friction with the piping during air pressure feeding. The outer jacket 30 may also contain an ultraviolet absorber to block ultraviolet rays from external light.

[0035] As described above, the optical fiber cable 1 of this embodiment includes a plurality of cores 111. Therefore, as a communication optical fiber cable, the optical fiber cable 1 can have a larger communication capacity than an optical fiber cable that does not include a plurality of cores.

[0036] Furthermore, in the optical fiber cable 1 of this embodiment, the fiber-reinforced plastic 20 encases the optical fiber 10. In a cross-sectional view, the optical fiber 10 is embedded in the fiber-reinforced plastic 20. If the fiber-reinforced plastic 20 did not encase the optical fiber 10 and the optical fiber 10 and the fiber-reinforced plastic 20 were spaced apart from each other, a space for accommodating both the optical fiber 10 and the fiber-reinforced plastic 20 would be required in the cross-sectional view, making it difficult to reduce the diameter of the entire optical fiber cable. However, according to this embodiment, the space for accommodating the optical fiber 10 is enclosed within the space for accommodating the fiber-reinforced plastic 20 in the cross-sectional view, eliminating the need for space, making it easy to reduce the diameter of the entire optical fiber cable 1. Therefore, even if other cables are already installed in the piping and the available space is limited, it is easy to install an additional optical fiber cable 1.

[0037] Additionally, according to this embodiment, the optical fiber cores 10 are densely packed within the fiber-reinforced plastic 20 while being encapsulated by the fiber-reinforced plastic 20, so that the optical fiber cores 10 are less likely to be subjected to strain stress. Furthermore, the fiber-reinforced plastic 20 can increase the bending rigidity of the optical fiber cable 1. As a result, the optical fiber cable 1 is less likely to buckle within the piping, making it easier to lay the optical fiber cable 1 within the piping. For example, the air-pressurized feeding distance of the optical fiber cable 1 is 1 km to 2 km, and this embodiment enables relatively long-distance laying. Furthermore, by using aramid fiber-reinforced plastic as the fiber-reinforced plastic 20, the linear expansion of the optical fiber cable 1 is also easily reduced.

[0038] In this embodiment, each optical fiber 10 is a multi-core fiber, which can increase the core density of the optical fiber cable 1. Therefore, the optical fiber cable 1 as a communication optical fiber cable can have a larger communication capacity than an optical fiber cable not including multiple cores.

[0039] In this embodiment, the outer diameter of the optical fiber cable 1 is 2 mm or less. Because the optical fiber cable 1 has a relatively small diameter, it is easy to install an additional optical fiber cable 1 even when other cables are already installed in the piping and the available space is limited.

[0040] In this embodiment, multiple optical fiber cores 10 are twisted together. This increases the bending rigidity of the optical fiber cable 1 compared to when multiple optical fiber cores are not twisted together. For example, when the optical fiber cable 1 is bent inside a pipe, the first side of the optical fiber cable 1, which is the outer side of the bend, bends more than the second side, which is the inner side of the bend and located opposite the first side. Even when bending strain is applied to the side of the optical fiber cable 1 in this way, the bending strain is easily dispersed by the twisted multiple optical fiber cores 10. This makes it easier to lay the optical fiber cable 1 inside a pipe.

[0041] (Modification 1) An optical fiber cable 1A according to Modification 1 will be described with reference to Fig. 2. In the configuration shown in Fig. 2, the same components as those shown in Fig. 1 are denoted by the same reference numerals, and descriptions thereof will be omitted.

[0042] Fig. 2 is a cross-sectional view perpendicular to the longitudinal direction of an optical fiber cable 1A according to Modification 1. While the optical fiber cable 1 illustrated in Fig. 1 includes a plurality of optical fiber cores 10, which are multi-core fibers, the optical fiber cable 1A illustrated in Fig. 2 includes a plurality of optical fiber cores 10A, which are single-core fibers. That is, the optical fiber cable 1A includes a plurality of optical fiber cores 10A, each of which is a single-core fiber, a fiber-reinforced plastic 20, and an outer jacket 30. The outer diameter of the optical fiber cable 1A is, for example, 2 mm or less.

[0043] The optical fiber cable 1A of this modification includes a plurality of optical fiber cores 10A. More specifically, twelve optical fiber cores 10A are arranged in the central portion of the optical fiber cable 1A. Each optical fiber core 10A is circular in cross section. The outer diameter of each optical fiber core 10A is, for example, 200 μm or less. The plurality of optical fiber cores 10A are twisted and arranged within the fiber-reinforced plastic 20.

[0044] Each optical fiber 10A includes a glass fiber 11A and a coating resin layer 12. The outer diameter of the glass fiber 11A is, for example, 125 μm. The glass fiber 11A includes one core 111A. The core 111A is provided, for example, in a region including the central portion of the glass fiber 11A. The central axis of the glass fiber 11A may coincide with the central axis of the core 111A. The outer diameter (MFD) of the core 111A is, for example, 9 μm.

[0045] The fiber reinforced plastic 20 is configured to contain a plurality of optical fiber cores 10A. In other words, the plurality of optical fiber cores 10A are arranged so as to be embedded in the fiber reinforced plastic 20 in a cross-sectional view.

[0046] The optical fiber cable 1A according to this modification also includes multiple cores 111A. Therefore, the optical fiber cable 1A is suitable for use as a communication optical fiber cable. Furthermore, since the optical fiber 10A is embedded in the fiber-reinforced plastic 20, the overall diameter of the optical fiber cable 1A can be easily reduced. The optical fiber 10A can be densely packed, and the optical fiber 10A is less susceptible to strain stress, making it easy to increase bending rigidity.

[0047] (Modification 2) An optical fiber cable 1B according to Modification 2 will be described with reference to Fig. 3. In the configuration shown in Fig. 3, the same components as those shown in Fig. 1 are denoted by the same reference numerals, and the description thereof will be omitted.

[0048] Fig. 3 is a cross-sectional view perpendicular to the longitudinal direction of an optical fiber cable 1B according to Modification 2. While the optical fiber cable 1 illustrated in Fig. 1 includes a plurality of optical fiber cores 10, which are multi-core fibers, the optical fiber cable 1B illustrated in Fig. 3 includes one optical fiber core 10B, which is a multi-core fiber. That is, the optical fiber cable 1B includes one optical fiber core 10B, which is a multi-core fiber, a fiber-reinforced plastic 20, and an outer jacket 30. The outer diameter of the optical fiber cable 1B is, for example, 2 mm or less.

[0049] The optical fiber cable 1B of this modification includes one optical fiber 10B. More specifically, the single optical fiber 10B is disposed in the center of the optical fiber cable 1B. The central axis of the optical fiber cable 1B and the central axis of the optical fiber 10B may coincide. The optical fiber 10B is circular in cross section. The outer diameter of the optical fiber 10B is, for example, 250 μm or less.

[0050] The optical fiber core 10B includes a glass fiber 11B and a coating resin layer 12. The outer diameter of the glass fiber 11B is, for example, 180 μm. The glass fiber 11B includes 12 cores 111B. The cores 111B are provided, for example, in a region including the central portion of the glass fiber 11B. The outer diameter (MFD) of the cores 111B is, for example, 9 μm.

[0051] The fiber reinforced plastic 20 is configured to enclose one optical fiber 10B. In other words, in a cross-sectional view, one optical fiber 10B is disposed so as to be embedded in the fiber reinforced plastic 20.

[0052] The optical fiber cable 1B according to this modification also includes multiple cores 111B. Therefore, the optical fiber cable 1B is suitable for use as a communication optical fiber cable. Furthermore, since the optical fiber 10B is embedded in the fiber-reinforced plastic 20, the overall diameter of the optical fiber cable 1B can be easily reduced. The optical fiber 10A can be densely packed, and the optical fiber 10B is less susceptible to strain stress, making it easy to increase bending rigidity.

[0053] REFERENCE SIGNS LIST 1, 1A, 1B Optical fiber cable 10, 10A, 10B Optical fiber core 11, 11A, 11B Glass fiber 111, 111A, 111B Core 112 Cladding 12 Coating resin layer 20 Fiber reinforced plastic 30 Outer jacket

Claims

1. An optical fiber cable comprising: at least one optical fiber core; a fiber-reinforced plastic that encases the optical fiber core; and an outer jacket that covers the fiber-reinforced plastic from the outside, wherein, in a cross-sectional view, the optical fiber core is embedded within the fiber-reinforced plastic.

2. The optical fiber cable according to claim 1, wherein the optical fiber core is a multi-core fiber.

3. The optical fiber cable according to claim 1, wherein the optical fiber core is a single-core fiber, and the optical fiber cable comprises a plurality of the optical fiber cores.

4. An optical fiber cable according to any one of claims 1 to 3, wherein the outer diameter of the optical fiber cable is 2 mm or less.

5. An optical fiber cable according to any one of claims 1 to 4, wherein the optical fiber cable comprises a plurality of the optical fiber core wires, and the plurality of the optical fiber core wires are twisted together.

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