Optical fiber cable and cable with connector

Abstract

This optical fiber cable includes: a cable core including a plurality of optical fiber core wires; at least one tensile strength body disposed along the cable core; and a sheath which covers the cable core from the outside and has the tensile strength body incorporated therein. The tensile strength body is provided at one location of the sheath in a cross-sectional view. The core density obtained by dividing the number of the plurality of optical fiber core wires by the cross-sectional area of the cable is 1.5 cores / mm2 or greater.

Description

Fiber optic cables and connectorized cables

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

[0002] Patent Document 1 discloses an optical fiber cable including a plurality of optical fiber cores, a strength member, and an outer jacket that covers the optical fiber cores from the outside and encases the strength member. The strength member makes the cable relatively easy to bend and provides the cable with tensile strength and anti-buckling properties.

[0003] U.S. Patent No. 6,137,936

[0004] An optical fiber cable according to one aspect of the present disclosure includes: a cable core including a plurality of optical fiber cores; at least one strength member arranged along the cable core; and an outer jacket that covers the cable core from the outside and encloses the strength member, wherein the strength member is provided at one location on the outer jacket in a cross-sectional view; and a core density, calculated by dividing the number of cores in the plurality of optical fiber cores by the cross-sectional area of ​​the cable, is 1.5 cores / mm ２ That's all.

[0005] A connectorized cable according to another aspect of the present disclosure comprises the optical fiber cable; and a multi-fiber connector having the plurality of optical fiber cores attached at one end of the optical fiber cable.

[0006] Fig. 1 is a cross-sectional view perpendicular to the longitudinal direction of an optical fiber cable according to an embodiment, Fig. 2 is a cross-sectional view perpendicular to the longitudinal direction of an optical fiber cable according to a modified example, and Fig. 3 is a schematic view illustrating a connectorized cable.

[0007] [Problem to be solved by the present disclosure] When an optical fiber cable has a structure in which strength members are arranged on both sides of the jacket around the cable core, it tends to bend easily in a 90-degree direction relative to the line connecting the strength members in a cross-sectional view, and tends to have low bending rigidity in that direction. On the other hand, it tends to bend less easily in the direction of the strength members, and tends to have high bending rigidity in that direction. In other words, an optical fiber cable with the above structure has bending anisotropy. When such an optical fiber cable is compressed air fed or pushed through a duct, it tends to bend easily in a direction with low bending rigidity, and may buckle midway through the duct.

[0008] Also known is an optical fiber cable in which strength members are arranged at four equal intervals in a cross-sectional view of the cable jacket. However, in such an optical fiber cable, the distance between the strength members embedded in the cable jacket and the bending center (which coincides with the center of the cable) is large. Therefore, when the cable is bent to a small diameter, compressive stress is applied to the inside of the bend, making the strength members arranged on the inside prone to buckling, breaking, and crushing. Furthermore, because it is difficult to bend the cable to a small diameter, a large space is required to accommodate the cable.

[0009] Furthermore, in order to mount optical fiber cores at high density, it is preferable that optical fiber cables be made thinner and lighter, and the optical fiber diameter has been reduced from the conventional 250 μm to 200 μm. To achieve high density, it is effective to make the outer jacket thinner, but when the outer jacket is thinner, the tensile strength members arranged on the inside are more likely to buckle when the cable is bent to a small diameter.

[0010] The present disclosure aims to provide an optical fiber cable and a cable with connectors that can pack optical fiber cores at high density and in which the tensile strength members are less likely to buckle even when the cable is bent to a small diameter.

[0011] (Explanation of an embodiment of the present disclosure) First, embodiments of the present disclosure will be listed and explained. An optical fiber cable according to an embodiment of the present disclosure includes: (1) a cable core including a plurality of optical fiber cores; at least one strength member arranged along the cable core; and an outer jacket that covers the cable core from the outside and encloses the strength member, wherein the strength member is provided at one location on the outer jacket in a cross-sectional view; and a core density, calculated by dividing the number of cores in the plurality of optical fiber cores by the cross-sectional area of ​​the cable, of 1.5 cores / mm ２ That's all.

[0012] According to the present disclosure, the core density is 1.5 cores / mm ２ As described above, an optical fiber cable with optical fibers packed at a high density can be realized. Furthermore, in the present disclosure, the strength member is provided at one location in the jacket when viewed in cross section. By embedding the strength member at one location, the bending center when the cable is bent is closer to the strength member, and the distance between the strength member and the bending center is shortened. Therefore, compared to when the strength members are embedded at two or more locations in the jacket, the strength member is less likely to buckle even when the cable is bent to a small diameter. Because the cable can be easily bent to a small diameter, the cable can be more easily stored in any space.

[0013] (2) In the above (1), the tension member may be made of fiber reinforced plastic (FRP).

[0014] According to the present disclosure, since the tension members are made of FRP, they have relatively high rigidity and are less likely to buckle.

[0015] (3) In the above (1) or (2), the Young's modulus of the reinforcing member may be 400 MPa or more and 700 MPa or less.

[0016] According to the present disclosure, the strength member is provided at one location on the outer jacket, and the Young's modulus of the strength member is 400 MPa or more and 700 MPa or less, so the strength member has a relatively low rigidity and is relatively flexible and resistant to buckling. If the Young's modulus of the strength member is less than 400 MPa, its function as a strength member is reduced, and its function as a compression resistance member against shrinkage of the outer jacket is also reduced. On the other hand, if the Young's modulus of the strength member is more than 700 MPa, the cable becomes difficult to bend, resulting in poor storage properties.

[0017] (4) In any one of the above (1) to (3), the product of Young's modulus and cross-sectional area (ES product) of the tensile member may be 1000 N or more and 10000 N or less.

[0018] According to the present disclosure, the strength member is provided at one location on the outer sheath, and the ES product of the strength member is 1,000 N or more and 10,000 N or less, so that the strength member is less likely to buckle.

[0019] (5) In the above (1), the tension member may be a steel wire.

[0020] According to the present disclosure, the tension member is provided at one location on the outer sheath, and the tension member is made of steel wire, so that the tension member has high rigidity and is less likely to buckle.

[0021] (6) In any one of the above (1) to (5), the diameter of the reinforcing member may be greater than the minimum thickness of the outer covering.

[0022] According to the present disclosure, the strength member is provided at one location on the jacket, and the diameter of the strength member is greater than the minimum thickness of the jacket, so that the center of rigidity of the cable is closer to the strength member than to the center of the cable, making the strength member less likely to buckle even when the cable is bent.

[0023] (7) In any one of the above (1) to (6), the strength member may not buckle when the optical fiber cable is bent at a bending radius that is 10 times the radius of the optical fiber cable.

[0024] It is possible to realize an optical fiber cable in which the tensile strength members are less likely to buckle even when the cable is bent to a small diameter.

[0025] (8) In any one of the above (1) to (7), the outer covering may contain a flame-retardant inorganic material.

[0026] According to the present disclosure, since the jacket contains a flame-retardant inorganic material, an optical fiber cable with excellent flame retardancy can be realized.

[0027] (9) In any one of the above (1) to (7), the outer jacket may be made of ethylene-vinyl acetate copolymer resin (EVA resin).

[0028] According to the present disclosure, since the outer jacket is made of ethylene-vinyl acetate copolymer resin (EVA resin), an optical fiber cable with excellent flame retardancy can be realized.

[0029] (10) In any one of the above (1) to (9), the Young's modulus of the outer jacket may be 400 MPa or more and 800 MPa or less.

[0030] According to the present disclosure, since the Young's modulus of the outer jacket is 400 MPa or more and 800 MPa or less, the cable is easily bent, improving the ease of storing the cable in any space.

[0031] (11) In any one of the above (1) to (10), the softening point of the jacket may be 40°C or higher and 70°C or lower.

[0032] If the softening point of the jacket is lower than 40°C, the jacket will easily soften even at room temperature, causing the cable to easily deform due to lateral pressure, etc. If the softening point of the jacket is higher than 70°C, the material will harden, making it more likely that transmission characteristics at low temperatures will deteriorate due to low-temperature shrinkage, etc. According to the present disclosure, an optical fiber cable with a softening point of the jacket between 40°C and 70°C can be realized that is less likely to deform even when lateral pressure, etc. is applied, and that exhibits good transmission characteristics even at low temperatures.

[0033] (12) In any one of the above (1) to (11), the tension members may be arranged in a spiral shape around the cable core in the longitudinal direction of the optical fiber cable.

[0034] According to the present disclosure, since the tensile members are arranged in a spiral shape, bending anisotropy is reduced and buckling of the cable is further suppressed.

[0035] (13) In any one of the above (1) to (12), in the cross-sectional view, the ratio of the area of ​​the tension members to the area of ​​the outer sheath may be 0.04 or more.

[0036] If the ratio of the area of ​​the strength members to the area of ​​the outer jacket is less than 0.04, the function as a strength member will be reduced, and the function as a compression resistance member will be reduced when the outer jacket shrinks. According to the present disclosure, since the ratio of the area of ​​the strength members to the area of ​​the outer jacket is 0.04 or more, the strength members are less likely to buckle.

[0037] (14) In any one of the above (1) to (13), the optical fiber cable may be a cable for air pressure transmission.

[0038] According to the present disclosure, it is possible to realize an optical fiber cable for air-fed transmission, which can pack optical fiber cores at a high density and in which the tensile members are less likely to buckle even when the cable is bent to a small diameter.

[0039] A connectorized cable according to another aspect of the present disclosure comprises: (15) an optical fiber cable according to any one of (1) to (14) above; and a multi-fiber connector to which the plurality of optical fiber cores are attached at one end of the optical fiber cable.

[0040] The present disclosure facilitates cable connections.

[0041] [Effects of the Present Disclosure] According to the present disclosure, it is possible to provide an optical fiber cable and a cable with a connector that can pack optical fiber cores at high density and in which the tensile strength members are less likely to buckle even when the cable is bent to a small diameter.

[0042] (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.

[0043] (Structure of Optical Fiber Cable) An optical fiber cable 1 according to this embodiment will be described with reference to Fig. 1. Fig. 1 is a cross-sectional view of the optical fiber cable 1 taken perpendicular to its longitudinal direction.

[0044] As illustrated in Fig. 1, the optical fiber cable 1 includes a cable core 11, one tensile member 12, and an outer jacket 13. The optical fiber cable 1 is circular in cross section. The outer diameter of the optical fiber cable 1 is, for example, 9.8 mm. A pressure winding tape or a bundling string may be wound around the outer periphery of the cable core 11. The optical fiber cable 1 of this embodiment is a slotless optical fiber cable and a cable for air pressure feeding.

[0045] The cable core 11 is circular in cross section. The cable core 11 includes a plurality of optical fiber ribbons 10. The outer diameter of the cable core 11 is, for example, 5.8 mm. In this embodiment, the cable core 11 has 24 optical fiber ribbons 10. The optical fiber ribbon 10 includes 12 optical fibers. The outer diameter of each optical fiber is, for example, 165 μm or more and 250 μm or less, which is relatively thin. The 12 optical fibers are arranged in parallel in a direction perpendicular to the longitudinal direction. At least some adjacent optical fibers in the optical fiber ribbon 10 may have connected portions where the adjacent optical fibers are connected and unconnected portions where the adjacent optical fibers are not connected, intermittently provided in the longitudinal direction of the optical fibers. The optical fiber ribbon 10 is an example of a plurality of optical fibers.

[0046] The core density, calculated by dividing the number of core fibers in the optical fiber core wires by the cross-sectional area of ​​the cable, is 1.5 cores / mm ２ The optical fiber cable 1 of this embodiment has 288 optical fiber cores in the cable core 11. The cross-sectional area of ​​the cable is 75.39 mm ２ The fiber density is 3.8 fibers / mm ２ is.

[0047] The strength members 12 are arranged along the cable core 11. In this embodiment, the strength members 12 are arranged spirally around the cable core 11 in the longitudinal direction of the optical fiber cable 1. The strength members 12 are further provided at one location on the jacket 13 in a cross-sectional view.

[0048] The tension members 12 are made of fiber-reinforced plastic (FRP). Examples of fiber-reinforced plastic include aramid FRP, glass FRP, and carbon FRP. The tension members 12 are circular in cross section. The diameter of the tension members 12 is, for example, 1.8 mm. The diameter of the tension members 12 is greater than the minimum thickness Tmin of the outer jacket 13, which will be described later. Furthermore, the ratio of the area of ​​the tension members 12 to the area of ​​the outer jacket 13 in cross section is 0.04 or more.

[0049] The Young's modulus of the tension member 12 is 400 MPa or more and 700 MPa or less. The product of the Young's modulus of the tension member 12 and the cross-sectional area of ​​the tension member 12 (ES product) is 1000 N or more and 10000 N or less.

[0050] The strength members 12 are provided so as not to buckle when the optical fiber cable 1 is bent at a bending radius that is 10 times the radius of the optical fiber cable 1. For example, in the case of the optical fiber cable 1 having an outer diameter of 9.8 mm described above, the strength members 12 will not buckle even when the optical fiber cable 1 is bent so as to have a bending radius of 49 mm.

[0051] The jacket 13 is provided to cover the cable core 11 from the outside and to enclose the tension members 12. The base resin of the jacket 13 in this embodiment is ethylene-vinyl acetate copolymer resin (EVA resin). The jacket 13 may contain a flame-retardant inorganic material. Examples of the flame-retardant inorganic material that the jacket 13 contains include magnesium hydroxide or aluminum hydroxide. The Young's modulus of the jacket 13 in this embodiment is 400 MPa or more and 800 MPa or less. The softening point of the jacket 13 is 40°C or more and 70°C or less.

[0052] The thickness of the jacket 13 is not constant in cross-sectional view, and has a minimum thickness Tmin. The minimum thickness Tmin of the jacket 13 is the thickness of the jacket portion where the distance between the cable core 11 and the outer edge of the optical fiber cable 1 is shortest. In this embodiment, the minimum thickness Tmin of the jacket 13 is the thickness of the jacket 13 located on the opposite side of the cable core 11 from the strength members 12 in cross-sectional view ( FIG. 1 ). For example, the diameter of the strength members 12 is 1.8 mm, while the minimum thickness Tmin of the jacket 13 is 1.3 mm. In this way, the diameter of the strength members 12 is greater than the minimum thickness Tmin of the jacket 13.

[0053] In a cross-sectional view, the ratio of the area of ​​the tension members 12 to the area of ​​the outer sheath 13 is 0.04 or more. For example, when the area of ​​the outer sheath is 49.0 mm ２ and the area of ​​the tension member 12 is 2.54 mm ２ In this case, the ratio of the area of ​​the strength members 12 to the area of ​​the outer sheath 13 is 0.05.

[0054] As described above, the optical fiber cable 1 of this embodiment includes a cable core 11 including a plurality of optical fiber ribbons 10, one strength member 12 arranged along the cable core 11, and an outer jacket 13 that covers the cable core 11 from the outside and encases the strength member 12. The core density, calculated by dividing the number of core fibers of a plurality of optical fiber cores by the cross-sectional area of ​​the cable, is 1.5 fibers / mm ２ As a result, an optical fiber cable 1 in which optical fiber cores are packed at a high density can be realized.

[0055] Furthermore, the strength members 12 are provided at one location in the jacket 13 in a cross-sectional view. Therefore, when the optical fiber cable 1 is bent, the center of bending is closer to the strength members 12, and the distance between the strength members 12 and the bending center is shorter. Therefore, compared to when the strength members 12 are embedded in two or more locations in the jacket 13, the strength members 12 are less likely to buckle even when the optical fiber cable 1 is bent to a small diameter. Because the optical fiber cable 1 can be easily bent to a small diameter, the optical fiber cable 1 can be more easily stored in any space.

[0056] (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 the description thereof will be omitted.

[0057] Fig. 2 is a cross-sectional view perpendicular to the longitudinal direction of the optical fiber cable 1A. The optical fiber cable 1 illustrated in Fig. 1 includes one strength member 12, whereas the optical fiber cable 1A illustrated in Fig. 2 includes two strength members 12A provided at one location on the jacket 13 in the cross-sectional view.

[0058] Two strength members 12A are adjacent to each other and form a pair of strength member sets 12S. This pair of strength member sets 12S is provided at one location on the outer jacket 13. Each strength member 12A is circular in cross section. The diameter of each strength member 12A is, for example, 1.2 mm. Furthermore, the ratio of the area of ​​the strength members 12A to the area of ​​the outer jacket 13 in cross section is 0.04 or more. In this modified example, the cable cross-sectional area is 75.4 mm ２ The cable core area is 26.4 mm ２ Therefore, the area of ​​the outer jacket 13 is 49.0 mm ２ The area of ​​the two tension members 12A is 2.26 mm ２ Therefore, the ratio of the area of ​​the tension members 12A to the area of ​​the outer jacket 13 is 0.046 in cross section.

[0059] In the optical fiber cable 1A of this modification, two strength members 12A (a pair of strength member sets 12S) are also provided at one location in the jacket 13. As a result, when the optical fiber cable 1A is bent, the bending center is closer to the two strength members 12A, and the distance between the two strength members 12A and the bending center is shorter. Therefore, the two strength members 12A are less likely to buckle. Since the optical fiber cable 1A can be easily bent to a small diameter, the optical fiber cable 1A can be more easily stored in any space.

[0060] Although the present disclosure has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the present disclosure. Furthermore, the number, position, shape, etc. of the components described above are not limited to the above embodiments, and can be changed to the number, position, shape, etc. that are suitable for implementing the present disclosure.

[0061] In the above description, the tension members 12 are made of fiber-reinforced plastic (FRP), but the tension members 12 are not limited to fiber-reinforced plastic (FRP). The tension members 12 may be steel wires. In this case, the tension members 12 have a relatively high rigidity, so that the tension members 12 are less likely to buckle even when the optical fiber cable 1 is bent.

[0062] In the above description, the strength members 12 are arranged spirally around the cable core 11 in the longitudinal direction of the optical fiber cable 1, but the arrangement of the strength members 12 is not limited to a spiral arrangement. The strength members 12 may also be arranged linearly along the cable core 11 in the longitudinal direction of the optical fiber cable 1.

[0063] A multi-fiber connector 101 may be provided at one end of the optical fiber cable 1 or the optical fiber cable 1A. Fig. 3 is a schematic diagram illustrating a connectorized cable 100. As shown in Fig. 3, the connectorized cable 100 includes the optical fiber cable 1 and a multi-fiber connector 101 having a plurality of optical fiber cores attached at one end of the optical fiber cable 1. The connectorized cable 100 may include the optical fiber cable 1A instead of the optical fiber cable 1. This configuration can facilitate the installation work when optically connecting the optical fiber cable 1 or the optical fiber cable 1A.

[0064] (Evaluation Experiment) The optical fiber cable 1 according to the embodiment was evaluated for the presence or absence of buckling of the strength members 12. The diameter of the optical fiber core was 200 μm. When the optical fiber cable 1 was bent to a bending radius of 150 mm in an environment of 70° C., it was visually confirmed whether or not the strength members 12 buckled.

[0065] Furthermore, the pumping distance and cable temperature characteristics of the optical fiber cable 1 were evaluated. The cable temperature characteristics were evaluated by measuring the loss when subjected to a temperature cycle from -30°C to +70°C in a drum state or in a state simulating installation, and a rating of "good" was given when the loss variation Δα during the test was 0.15 dB / km or less.

[0066] The pumping distance was evaluated using the microduct pumping test specified by the IEC (International Electrotechnical Commission) (IEC60794-1-21 Method E24). A general-purpose microduct was used for the pumping test. The total pumping distance within the duct was set to 1,000 m or more, and the duct was arranged so that it turned back every 100 m. The radius of curvature of the duct was 40 times the outer diameter of the duct. The pressure within the duct was 1.3 MPa to 1.5 MPa.

[0067] The optical fiber cable 1A according to the modified example was also evaluated for the presence or absence of buckling of the tension members 12A, the pumping distance, and the cable loss characteristics. The evaluation results are shown in Table 1.

[0068] In Table 1, optical fiber cable Z is a comparative example. Optical fiber cable Z is a slotless cable. In cross-sectional view, four pairs of strength member sets are arranged at equal intervals at four locations on the outer sheath. Each strength member is made of aramid FRP and has a diameter of 0.5 mm. In optical fiber cable Z, of the four pairs of strength member sets, the strength member set corresponding to the inner side of the bend buckled. The temperature characteristics were "good." It was confirmed that the pumping distance of optical fiber cable Z was 1,000 m or more.

[0069] As shown in Table 1, no buckling of the strength members 12 of the optical fiber cable 1 was confirmed. The temperature characteristics of the optical fiber cable 1 were "good." Furthermore, it was confirmed that the pumping distance of the optical fiber cable 1 was 1,000 m or more. From the above, it was confirmed that the optical fiber cable 1 has good temperature characteristics and pumping distance, and that the configuration in which one strength member 12 is provided at one location on the jacket 13 makes the strength member 12 less likely to buckle.

[0070] Similarly, buckling of the strength members 12A of the optical fiber cable 1A was not confirmed. The temperature characteristics of the optical fiber cable 1A were "good." Furthermore, it was confirmed that the pumping distance of the optical fiber cable 1A was 1,000 m or more. From the above, it was confirmed that the optical fiber cable 1A has good temperature characteristics and pumping distance, and that even in a configuration in which one strength member set 12S (a pair of strength members 12A) is provided at one location on the jacket 13, the strength members 12A are not likely to buckle.

[0071] 1, 1A: Optical fiber cable 10: Optical fiber ribbon 11: Cable core 12, 12A: Tensile member 13: Jacket 100: Cable with connector 101: Multi-core connector Tmin: Minimum thickness of jacket

Claims

1. a cable core including a plurality of optical fiber cores; at least one strength member disposed along the cable core; an outer jacket that covers the cable core from the outside and encloses the strength members, the tensile member is provided at one location on the outer sheath in a cross-sectional view, The core density obtained by dividing the number of core fibers of the plurality of optical fiber cores by the cross-sectional area of ​​the cable is 1.5 cores / mm ２ That's it, fiber optic cable.

2. 2. The optical fiber cable according to claim 1, wherein the strength member is fiber reinforced plastic (FRP).

3. 2. The optical fiber cable according to claim 1, wherein the Young's modulus of the tensile member is 400 MPa or more and 700 MPa or less.

4. 2. The optical fiber cable according to claim 1, wherein the product of Young's modulus and cross-sectional area (ES product) of the tensile member is 1000 N or more and 10000 N or less.

5. The optical fiber cable according to claim 1 , wherein the strength members are steel wires.

6. 2. The optical fiber cable according to claim 1, wherein the diameter of the strength member is greater than the minimum thickness of the jacket.

7. 2. The optical fiber cable according to claim 1, wherein the strength member does not buckle when the optical fiber cable is bent at a bending radius that is 10 times the radius of the optical fiber cable.

8. The fiber optic cable of claim 1 , wherein the jacket comprises a flame-retardant inorganic material.

9. 2. The optical fiber cable according to claim 1, wherein the outer jacket is made of ethylene-vinyl acetate copolymer resin (EVA resin).

10. 2. The optical fiber cable according to claim 1, wherein the Young's modulus of the jacket is 400 MPa or more and 800 MPa or less.

11. 2. The optical fiber cable according to claim 1, wherein the softening point of the jacket is 40° C. or higher and 70° C. or lower.

12. 2. The optical fiber cable according to claim 1, wherein the strength members are arranged helically around the cable core in the longitudinal direction of the optical fiber cable.

13. 2. The optical fiber cable according to claim 1, wherein, in the cross-sectional view, a ratio of an area of ​​the strength members to an area of ​​the jacket is 0.04 or more.

14. The optical fiber cable according to claim 1 , wherein the optical fiber cable is a pneumatic cable.

15. The optical fiber cable according to any one of claims 1 to 14; a multi-fiber connector to which the plurality of optical fiber cores are attached at one end of the optical fiber cable; and