JP2018180361A - Optical fiber cable - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide, in view of the present circumstances, a slotless optical fiber cable that offers good strength but is easily bent and laid through conduit lines.SOLUTION: An optical fiber cable 1 is provided, comprising a cable core 10 accommodating a plurality of optical fiber core wires, and a first cable jacket 11 covering the cable core. No tension members are provided in the cable core and the cable jacket. Preferably, the first cable jacket has a tensile elasticity of 350 kgf/mmor more and 1,500 kgf/mmor less or a tensile strength of 5 kgf/mmor more and 15 kgf/mmor less.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a slotless optical fiber cable in which a plurality of optical fiber cores are covered with a cable jacket.

  As an optical fiber cable for multiple cores, for example, a slot type or slotless type is known. In the slot type, an optical fiber core wire is housed in a slot rod (also referred to as a spacer), the outer periphery thereof is wound with a winding tape, and a cable sheath (also referred to as a sheath) is provided. In this slot type, the cable sheath and the slot rod protect the optical fiber core against the pressure from the side of the optical fiber cable (hereinafter referred to as the side pressure). In addition, a tension member (also referred to as a tensile member) is provided at the center so as to withstand tensile force or compressive force. Since the slot type has a tension member at the center, directionality to bending does not occur, but since the tension member and the slot rod are present in the cable core, it is difficult to reduce the diameter and to increase the number of cores.

  On the other hand, in the slotless type, the optical fiber core is covered with, for example, inclusions, and a cable jacket is provided on the outer periphery thereof. In the slotless type, a tension member is embedded in the cable sheath to withstand tensile force or compressive force. For example, Patent Document 1 discloses a structure of an optical fiber cable in which two tension members are embedded in a cable jacket.

JP 2004-354448 A

  The slotless type is more likely to be multi-cored than the slot type, but when two tension members are arranged in the cable jacket as in Patent Document 1, the optical fiber cable connects the centers of these tension members. Since it is hard to bend in the direction (also referred to as the longitudinal direction of the cable), there is a problem that it is difficult to lay in a pipeline.

  The present invention has been made in view of the above situation, and an object of the present invention is to provide an optical fiber cable which is easy to bend and easy to lay in a conduit while maintaining strength in a slotless type optical fiber cable. Do.

  An optical fiber cable according to one aspect of the present invention is an optical fiber cable comprising a cable core for housing a plurality of optical fiber cores, and a first cable jacket covering the periphery of the cable core, There are no tension members in the core and in the cable jacket.

  According to the above, it is possible to provide a slotless optical fiber cable that is easy to bend and easy to lay in a conduit while maintaining strength.

FIG. 1 shows an example of an optical fiber cable according to an embodiment of the present invention. It is a figure for demonstrating the tension test of an optical fiber cable. It is a table | surface for demonstrating the evaluation result of the transmission characteristic of an optical fiber.

Description of the embodiment of the present invention
First, the contents of the embodiment of the present invention will be listed and described.
An optical fiber cable according to one aspect of the present invention is an optical fiber cable including: (1) a cable core for housing a plurality of optical fiber cores; and a first cable jacket covering the periphery of the cable core There is no tension member in the cable core and in the cable jacket. Because the strength of the first cable jacket is strong, it is possible to withstand the load applied to the optical fiber cable at the time of laying or the like even without the tension member. In addition, since the tension member to be inserted into the jacket can be omitted, it is possible to provide an optical fiber cable which is easy to be laid in a pipeline without directionality of bending.

(2) The tensile modulus of elasticity of the first cable jacket is 350 (kgf / mm ² ) or more and 1500 (kgf / mm ² ) or less (3433.5 × 10 ⁶ (Pa) or more and 14715 × 10 ⁶ (Pa) Or the tensile strength of the first cable jacket is 5 (kgf / mm ² ) or more and 15 (kgf / mm ² ) or less (49.5 × 10 ⁶ (Pa) or more and 147.15). × 10 ⁶ (Pa) or less). If the tensile elastic modulus is less than 350 (kgf / mm ² ) or if the tensile strength is less than 5 (kgf / mm ² ), the strength of the jacket is insufficient and lateral pressure is applied to the optical fiber, The transmission loss measured after the tensile test increases than before the tensile test. On the other hand, when the tensile elastic modulus exceeds 1500 (kgf / mm ² ) or when the tensile strength exceeds 15 (kgf / mm ² ), the rigidity of the cable becomes high and it is difficult to bend. Therefore, if the tensile modulus is in the range of 350 (kgf / mm ² ) to 1500 (kgf / mm ² ), or if the tensile strength is in the range of 5 (kgf / mm ² ) to 15 (kgf / mm ² ) Thus, it is possible to provide a flexible optical fiber cable while suppressing an increase in transmission loss.
(3) The thickness of the first cable jacket is in the range of 1.0 (mm) to 2.5 (mm). If the thickness is in the range of 1.0 (mm) to 2.5 (mm), the first cable jacket can have an appropriate range of strength, and the cable diameter is also smaller than that of the conventional one. Because it does not grow large.

(4) The reinforcing material is filled in the first cable jacket. If the reinforcing material is filled in the first cable sheath, the sheath can be further thinned, and the diameter reduction and multicore formation of the cable can be achieved.
(5) The present invention further comprises a second cable jacket which covers the periphery of the first cable jacket and has weather resistance. If it is covered with the second cable jacket, it can also have weather resistance, so it can be provided as an outdoor optical fiber cable.

Details of the Embodiment of the Present Invention
Hereinafter, preferred embodiments of the optical fiber cable according to the present invention will be described with reference to the attached drawings.
FIG. 1 is a view showing an example of a fiber optic cable according to an embodiment of the present invention. The optical fiber cable 1 has a cable core 10 at the center, the outer side of the cable core 10 is covered with a first cable jacket 11, and the outer side of the first cable jacket 11 is a second cable jacket 12 It is covered with

For example, six tape cores 13 are accommodated in the cable core 10. In detail, for example, four tape cores 13 are stacked, and one of the tape cores 13 is disposed on the side, and it is twisted and gathered in, for example, a spiral along the longitudinal direction of the cable.
For example, four optical fiber cores are arranged in parallel and integrated in a tape form with a common coating over the entire length.

The optical fiber core is, for example, a glass fiber with a standard outer diameter of 125 μm and a coating with a coating outer diameter of about 250 μm and a colored fiber sheath further provided with a colored coating, The present invention is not limited to this, and it may be a fine diameter fiber with a coating outer diameter of about 165 μm and about 200 μm. The number of optical fiber cores can be selected to be any number of cores, such as two or eight.
Also, instead of the above-mentioned tape core wire 13, four single core wires or intermittent tape core wires may be used. The intermittent tape cores are formed by arranging a plurality of optical fiber cores in parallel parallel lines and intermittently connecting adjacent optical fiber cores by the connecting portion and the non-connecting portion. In addition, it is not necessary to provide a connection part and a non-connection part for every 1 core, for example, you may provide for every 2 cores.

  Inclusions 14 are provided around the bundle of tape cores 13. The inclusions 14 are, for example, fibrous members of polypropylene (PP), and a total of six inclusions 14 are disposed around the bundle of the tape cores 13, for example. The inclusions 14 are not limited to polypropylene, and yarns made of resin such as polyethylene (PE) or polyethylene terephthalate (PET) may be used.

  The holding and winding tape 15 is, for example, a non-woven fabric containing polyethylene terephthalate (PET) or the like, and is wound, for example, spirally from the outside of the inclusion 14 or wound longitudinally in the longitudinal direction of the cable. Thereby, a cable core 10 having a diameter of, for example, about 10 mm is formed. In order to stop water in the optical fiber cable 1, a water absorbing agent may be applied to the holding and winding tape.

  The first cable jacket 11 has a predetermined tensile modulus, tensile strength, and thickness as a member having appropriate strength in order to have the same function as a tension member that withstands tensile force or compressive force in the longitudinal direction of the cable. Material (e.g., cycloolefin copolymer (COC), ABS resin, polyacetal (POM), etc.) and provided on the outside of the cable core 10 by extrusion. The first cable jacket 11 may be filled with a reinforcing material such as glass fiber, carbon fiber, or aramid fiber.

As described above, since the first cable jacket 11 has the same strength as that of the tension member, even without the tension member, the load applied to the optical fiber cable can be resisted when laying or the like. In addition, since the tension member to be inserted into the jacket can be omitted, it is possible to provide an optical fiber cable which is easy to be laid in a pipeline without directionality of bending.
In addition, if the reinforcing material is filled in the first cable sheath 11, the sheath can be further thinned, and the diameter reduction and multicore formation of the cable can be achieved.

As shown in FIG. 1, a second cable jacket 12 may be provided on the outside of the first cable jacket 11. The second cable jacket 12 is provided to provide weather resistance to the optical fiber cable, and is formed of, for example, low density polyethylene (LLDPE) having a thickness of 1.5 (mm), and is formed by extrusion molding. It is provided on the outer side of the cable jacket 11 of 1. The low density polyethylene refers to polyethylene having a density of less than 0.942 g / cm ³ .

As described above, weather resistance can be provided by covering with the second cable jacket, so that it can be provided as an outdoor optical fiber cable.
The second cable jacket 12 is intended for weatherability, and the strength is not strong. For example, the tensile modulus and tensile strength when the low density polyethylene is used as the second cable jacket 12. The length is substantially the same as in the case of only the first cable jacket 11 which is not covered by the second cable jacket 12.

FIG. 2 is a figure for demonstrating the tension test of an optical fiber cable, FIG. 3 is a table | surface for demonstrating the evaluation result of the transmission characteristic of an optical fiber.
In addition, in the transmission characteristic of FIG. 3, after applying tensile force to the optical fiber cable 1 of the said structure by the method of FIG. 2, the transmission loss was measured with the OTDR (Optical Time Domain Reflectmeter) measuring device.

  The tensile test uses a test jig 50 as shown in FIG. The test jig 50 includes a cylindrical metal fitting 60 and a cable holding portion 51. The cylindrical metal fitting 60 is made of metal with an inner diameter of about 7 mm and an outer diameter of about 9 mm, and the cable core 10 of the optical fiber cable 1 is fitted inside, and the first cable jacket 11 covering the cable core 10 The second cable jacket 12 may be placed on the outside of the tubular fitting 60).

  The cable gripping portion 51 is made of, for example, cylindrical aluminum, and the metal fitting portion 52 is installed at one end of the cable gripping portion 51. The cable grip portion 51 is put on the cylindrical member 60 and the first cable jacket 11 and caulked, and the optical fiber cable 1 is fixed to the test jig 50. The metal fitting portion 52 and the cylindrical metal fitting 60 are held by the chuck of a tensile tester, and a predetermined tensile force (for example, 981 (N)) is applied in a longitudinal direction of the cable for a predetermined time (for example, one minute).

  For the transmission characteristics, after releasing the tensile force, remove the test jig 50 from the optical fiber cable 1 and abut the end of the optical fiber in the cable core 10 with the end of the measurement dummy fiber of the OTDR measurement device to measure the OTDR The measurement light pulse (measurement wavelength 1300 (nm)) was output to the cable core 10 from the device to measure the transmission loss. Then, the quality (○ ×) was evaluated based on whether the amount of increase in light loss before and after the tensile test was 0.1 (dB) or less.

The first cable jacket 11 described in FIG. 1 is pulled by pulling the 4-core optical fiber ribbon and twisting the six cable strands together with the PP yarn interposed thereon, the cable core of 10 mm in diameter having the holding and winding tape applied. The modulus of elasticity was 350 (kgf / mm ² ) (= 3433.5 × 10 ⁶ (Pa); 1 (kgf / mm ² ) was calculated at 9.81 × 10 ⁶ (Pa), the same applies hereinafter), tensile strength In the case of an optical fiber cable with a cycloolefin copolymer (COC) of 5 (kgf / mm ² ) (= 49.5 × 10 ⁶ (Pa)) and a thickness of 2.0 (mm) (referred to as “sample 1” As shown in FIG. 3, the optical loss increase amount is 0.05 (dB) and is 0.1 (dB) or less.

Next, the first cable jacket 11 to be placed on the cable core having the same structure as that of the sample 1 has a tensile modulus of 550 (kgf / mm ² ) (= 5395.5 (Pa)) and a tensile strength of 7.0. (Kgf / mm ² ) (= 68.67 (Pa)), a glass fiber filled with 20% by weight ratio, and in the case of an optical fiber cable made of ABS resin with a thickness of 1.0 (mm) (“Sample 2” As shown in FIG. 3, the optical loss increase amount was 0.05 (dB), and it was determined to be good.

Subsequently, the first cable jacket 11 to be placed on the cable core having the same structure as the samples 1 and 2 was subjected to a tensile modulus of 1000 (kgf / mm ² ) (= 9810 (Pa)) and a tensile strength of 10.0. (Kgf / mm ² ) (= 98.1 (Pa)), in the case of an optical fiber cable filled with glass fiber at a weight ratio of 25% to a polyacetal (POM) thickness of 1.0 (mm) (“Sample 3 As shown in FIG. 3, the optical loss increase amount was 0 (dB), and it was judged as good.

On the other hand, the first cable jacket which covers the cable core having the same structure as the samples 1 to 3 has a tensile modulus of 1000 (kgf / mm ² ) (= 9810 (Pa)) and a tensile strength of 1.5. In the case of an optical fiber cable made of high-density polyethylene (HDPE) (kgf / mm ² ) (= 14.715 (Pa)) and a thickness of 2.0 (mm) (referred to as “sample 4”), the tensile test Cable breakage was observed. For this reason, as shown in FIG. 3, the amount of increase in optical loss was not measured, and it was determined to be defective.

In addition, the first cable jacket to be placed on the cable core having the same structure as in Samples 1 to 3 has a tensile modulus of 300 (kgf / mm ² ) (= 2943 (Pa)) and a tensile strength of 3.5 (kgf) In the case of an optical fiber cable made of ABS resin with a thickness of 1.0 (mm) / mm ² ) (= 34.335 (Pa)) (referred to as “Sample 5”), as shown in FIG. The amount of increase was 5 (dB), and it was determined to be defective.

Although illustration is omitted, when the tensile modulus exceeds 1500 (kgf / mm ² ) (= 14715 × 10 ⁶ (Pa)) or the tensile strength is 15 (kgf / mm ² ) (= 147) If it exceeds 15 × 10 ⁶ (Pa)), the rigidity of the cable becomes high and it becomes difficult to bend.

Thus, if the tensile modulus of the first cable jacket is less than 350 (kgf / mm ² ), or if the tensile strength is less than 5 (kgf / mm ² ), the strength of the jacket is Since the optical fiber is stretched and strained due to the tensile force, and the fiber is brought into contact with other fibers and bent when stretched, the transmission loss measured after the tensile test increases compared to before the tensile test. In addition, there was also a case where breakage occurred due to insufficient strength. On the other hand, when the tensile elastic modulus exceeds 1500 (kgf / mm ² ) or when the tensile strength exceeds 15 (kgf / mm ² ), the rigidity of the cable becomes high and it is difficult to bend. Therefore, if the tensile modulus is in the range of 350 (kgf / mm ² ) to 1500 (kgf / mm ² ), or if the tensile strength is in the range of 5 (kgf / mm ² ) to 15 (kgf / mm ² ) Thus, it is possible to provide a flexible optical fiber cable while suppressing an increase in transmission loss.

  If the thickness of the first cable jacket is in the range of 1.0 (mm) to 2.5 (mm), the strength of the appropriate range can be obtained, and the cable diameter is also the conventional one. It is preferable because it does not grow larger than one.

  It should be understood that the embodiments disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is indicated not by the meaning described above but by the claims, and is intended to include all modifications within the meaning and scope equivalent to the claims.

DESCRIPTION OF SYMBOLS 1 ... Optical fiber cable, 10 ... Cable core, 11 ... 1st cable jacket, 12 ... 2nd cable jacket, 13 ... Tape core, 14 ... Inclusion, 15 ... Presser | winding tape, 50 ... Test recovery Tools, 51: Cable gripping portion, 52: Bracket portion, 60: Tubular bracket.

Claims (5)

An optical fiber cable comprising: a cable core for housing a plurality of optical fiber cores; and a first cable jacket covering the periphery of the cable core,
Fiber optic cable with no tension member in the cable core and cable jacket. Said first cable jacket of tensile modulus at 350 (kgf / mm ²⁾ or more 1500 (kgf / mm ²⁾ or less (3433.5 × 10 ⁶ (Pa) over 14715 × 10 ⁶ (Pa) or less) Or the tensile strength of the first cable jacket is 5 (kgf / mm ² ) or more and 15 (kgf / mm ² ) or less (49.5 × 10 ⁶ (Pa) or more) 147.15 × 10 ⁶ The optical fiber cable according to claim 1, which is (Pa) or less.   The fiber optic cable according to claim 1 or 2, wherein the thickness of the first cable jacket is in the range of 1.0 (mm) to 2.5 (mm).   The optical fiber cable according to any one of claims 1 to 3, wherein the first cable jacket is filled with a reinforcing material. The fiber optic cable according to any one of claims 1 to 4, further comprising a weatherproof second cable jacket covering the periphery of the first cable jacket.

Images