JP4388006B2 - Optical cable - Google Patents

Description

  The present invention relates to an optical cable used as an optical drop cable, an optical indoor cable, or the like for drawing and wiring from a wiring system cable to a subscriber's house such as a building or a general house.

  In recent years, with the spread of communication services such as the Internet, FTTH (Fiber To The Home), which connects all sections from a telecommunications carrier to a subscriber's home with an optical fiber, has been rapidly expanding. In such FTTH, the optical wiring network in the vicinity of the subscriber's house is generally an overhead wiring using a power pole, and the main method is to drop the wiring cable from the wiring pole to the subscriber's house using an optical drop cable. Has been adopted.

  FIG. 16A shows an example of such an optical drop cable. As shown in the figure, this optical drop cable has two single-core optical fiber cores 1 sandwiched between a steel wire, glass fiber reinforced plastic (G-FRP), and aramid fiber reinforced plastic (K-FRP). ) And the like, a support wire 3 is further disposed thereon, and a thermoplastic resin such as polyethylene is collectively coated on the outer periphery of the tension members 2 and 2 to provide a jacket 4. A connecting portion (neck portion) 7 that divides the cable into a supporting wire portion 5 and a cable portion 6 is provided between the supporting wire 3 and the strength member 2 of the cable. Notches 8 and 8 having a V-shaped cross-section for tearing are provided at substantially central portions of the upper and lower surfaces.

  In such an optical drop cable, since the support wire 3 is provided, aerial laying is possible. And since the connection part 7 is provided, after drawing a cable to a subscriber's house, the cable part 6 can be isolate | separated from the support wire part 5, and only the cable part 6 can be used for indoor wiring. FIG. 16B is a cross-sectional view showing a state in which the support line portion 5 is separated from the optical drop cable. Further, since the tension member 2 is disposed with the single-core optical fiber core 1 interposed therebetween, it is possible to prevent an increase in transmission loss of the optical fiber due to a temperature change, and tensile stress when the cable portion 6 is wired indoors. It is also possible to prevent disconnection of the optical fiber due to.

  However, in such a conventional optical drop cable, since the cross-sectional shape of the cable portion 6 is rectangular or elliptical, directionality occurs in the bending direction (usually the direction indicated by the arrow in FIG. 16 (b), That is, it bends in the width direction of the cable.) For this reason, there has been a problem that indoor wiring work, particularly wiring work in a narrow place or a winding place is not easy.

  In addition, since the outer sheath 4 is directly coated on the single-core optical fiber core wire 1, there is a problem that the outer sheath 4 is easily damaged by a semi-spawning (especially Kumazemi) oviduct. That is, when a semi-vibrated laying tube is pierced into the outer jacket 4, there is no hard protective layer or protective member or the like around the single-core optical fiber core wire 1 so as to prevent the entry of the laying tube in particular. The tip of the egg-laying tube easily reaches the single-core optical fiber 1, and as a result, the optical fiber 1 is damaged, and the optical fiber may be disconnected in some cases.

  Furthermore, the optical cable is usually fixed to a wall or the like using a staple or the like when wiring, but in the optical drop cable, when a general staple or the like is used, a local force is applied to the optical fiber core wire, There was a risk of increased transmission loss and disconnection of the optical fiber.

  Therefore, an optical cable that does not cause directionality in the bending direction of the cable part and has excellent wiring workability, and that does not increase transmission loss or break the optical fiber due to the entry of a semi-vibrating tube or handling during wiring. It is requested.

  On the other hand, as a structure to protect the optical fiber or the optical fiber core, (1) a submarine cable in which a groove is formed in a wire made of steel and the optical fiber core is housed in this groove, and (2) the outside is covered with metal (3) A cable in which a tensile strength fiber is vertically attached to the outer periphery of the optical fiber core and a jacket is provided on the outer side thereof has been proposed (for example, see Patent Documents 1 to 3).

However, (1) is a submarine cable that has different usage and required characteristics from an optical drop cable, etc., and (2) is a so-called metal-coated optical fiber, which cannot be used for an optical drop cable. . Furthermore, (3) is not sufficient as a measure for preventing the entry of the seminiferous oviduct. Therefore, even if these techniques are applied, it has not been possible to obtain an optical cable that satisfies the above requirements.
Japanese Patent Laid-Open No. 54-130039 JP-A-56-78802 JP 2003-331658 A

  The present invention has been made in response to such a conventional situation, and is excellent in wiring workability because there is no directionality in the bending direction of the cable or cable part, and is transmitted by entering a semi-vibrating tube or handling during wiring. An object of the present invention is to provide an optical cable in which loss does not increase and an optical fiber is not broken.

In order to achieve the above object, an optical cable of the present invention is an optical cable including a cable portion and a support wire portion that supports the cable portion, and the cable portion extends in a longitudinal direction to a tensile strength wire having a circular cross section. A tension member provided with an extending U-shaped or V-shaped groove, an optical fiber core housed in the groove, and a circular outer jacket provided on the outer periphery thereof;
The groove of the tension member has an opening on the support line portion side, and is formed in a size and shape so that the optical fiber core wire can freely rotate without deforming the outer shape in the groove. It is characterized in that there.

According to the optical cable of the present invention, since there is no directionality in the bending direction of the cable portion , the wiring work can be performed with good workability. In addition, since the optical fiber core is housed in the groove provided in the tension member, it is possible to reduce the risk of an increase in transmission loss or disconnection of the optical fiber core due to the entry of a semi-vibrating tube and handling during wiring. it can.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a cross-sectional view showing an embodiment of the optical cable of the present invention.

  The optical cable 101 of this embodiment is used as an optical drop cable for drawing and wiring from a wiring cable installed between utility poles to a subscriber's house such as a building or a general house. And a connecting portion 30 for connecting them.

  The cable portion 10 includes a tension member 14 in which a U-shaped or V-shaped groove 12 extending in the length direction is provided on a tensile strength wire having a circular cross section, and one single-core optical fiber core housed in the groove 12. A wire 16 and a jacket 18 formed by extruding and coating a thermoplastic resin such as polyethylene in a pipe shape on the outer periphery thereof. The outer casing 18 has a circular cross section.

  The support wire portion 20 includes a support wire 22 made of a steel wire and the like, and a sheath 24 that is integrally coated with the outer cover 18 and the connecting portion 30 of the cable portion 10 on the outer periphery thereof. The covering 24 also has a circular cross section.

In the present embodiment, the groove 12 has an opening on the support wire portion 20 side, the single-core optical fiber core wire 16 is positioned substantially at the center of the tension member 14, and the groove 12. It is formed in a shape and size that can be freely rotated without deforming its outer shape. That is, the depth of the groove 12 is slightly deeper than the center of the tensile strength wire , and the width thereof is larger than the outer diameter of the single-core optical fiber 16 so that the single-fiber optical fiber 16 can be rotated without deforming its outer shape. Slightly widely formed.

  The single-core optical fiber core wire 16 is not particularly limited, and examples include those in which the outer periphery of the optical fiber is coated with a silicone resin or an ultraviolet curable resin, and the outer periphery of which is further coated with a polyamide resin. .

  Further, as the tensile strength wire forming the tension member 14, a wire rod made of polyethylene terephthalate subjected to stretching treatment, or a metal wire such as an aluminum wire or an aluminum alloy wire is used.

  Furthermore, as the thermoplastic resin forming the outer sheath 18, polyolefin resins such as polyethylene, polypropylene, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, ethylene-propylene copolymer, vinyl chloride resin, Examples thereof include polyamide resin and polyurethane resin. These resins may contain a flame retardant and a colorant.

  For example, as shown in FIG. 2, the optical cable 101 according to the present embodiment is connected to a wiring system cable 42 installed in an aerial configuration in a closure (not shown), and is wired outdoors to the eaves of the subscriber house 44. Therefore, as shown in FIG. 3, the support wire portion 20 is separated, and only the cable portion 10 is drawn into the subscriber house 44 and wired indoors. The support line portion 20 is fixed to the wall surface of the house of the subscriber's house 44. As shown in FIG. 3 (b), the cable portion 10 to be wired indoors has a circular cross-sectional shape, and the tension member 14 that bears the tensile stress at the time of wiring is arranged at the center of the cable. The direction of bending is very small compared to conventional optical drop cables. That is, there is no significant difference in the bendability regardless of the direction indicated by the arrow in FIG. It can be performed.

  Thus, in the optical cable 101 of this embodiment, since the directionality of the bending direction of the cable part 10 is small, wiring work can be performed with respect to the cable part 10 with good workability.

  Further, in the optical cable 101 of the present embodiment, since the single-core optical fiber 16 is housed in the groove 12 provided in the tension member 14, the optical fiber core due to the entry of the semi-vibrating tube and handling during wiring. The increase in transmission loss and the risk of disconnection can be reduced. In particular, in this embodiment, since the groove 12 is open to the support wire portion 20 side, even if the semi-vibrated laying tube may pierce the jacket 18 of the cable portion 10 or the coating 24 of the support wire portion 20, As shown in FIG. 4, since the tip of the tension member 14 and the support wire 22 does not reach the single-core optical fiber core wire 16, damage caused by the semi-vibrating tube can be completely prevented. it can. In FIG. 4, X and Y indicate the entry directions of the semi-vibrated oviduct, and the tension member 14 and the support wire 22 prevent the reaching of the single-fiber optical fiber 16 from each other.

  Further, in the present embodiment, the single-core optical fiber core wire 16 is positioned at the approximate center of the tension member 14 and can be freely rotated without deforming the outer shape in the groove 12, so that the optical cable 101 is bent. The bending distortion of the single-core optical fiber 16 generated in the above can be reduced, and an increase in transmission loss due to bending can be prevented.

  In the present invention, from the viewpoint of reducing the directionality of the cable portion 10 in the bending direction, the tension member 14 provided with the groove 12 has a bending rigidity (M) in the depth direction of the groove that maximizes the bending rigidity. The ratio (M / N) of the bending rigidity (M) in the depth direction of the groove and the bending rigidity (N) in the direction orthogonal to the depth direction of the groove is not less than 4900 MPa and is not less than 1.0, 2.0 It is preferable to be as follows. The bending rigidity (M) in the depth direction of the groove is more preferably 4500 MPa or less, and even more preferably 4000 MPa or less. The ratio (M / N) of the bending rigidity (M) in the depth direction of the groove to the bending rigidity (N) in the direction perpendicular to the depth direction of the groove is 1.0 or more and 1.8 or less. Is more preferably 1.0 or more and 1.5 or less. Here, the bending rigidity is a value measured for the tension member 14 provided with the groove 12 in accordance with a JIS C 6851 optical fiber cable characteristic test method.

  Further, in order to suppress an increase in bending strain generated in the single-core optical fiber 16 when the single-core optical fiber 16 is moved in the radial direction in the groove 12 and the optical cable 101 is bent, the groove 12 is suppressed. You may make it insert a core wire movement prevention material in the inside.

  As shown in FIG. 5, the core wire movement preventing material may be formed by inserting the resin forming the outer cover 18 into the groove 12 of the tension member 14 when covering the outer cover 18. Moreover, you may fill and form buffer materials, such as a fiber, a string, and jelly. That is, the optical cable 102 shown in FIG. 5 is an example in which the core wire movement preventing member 191 made of resin forming the outer cover 18 is inserted into the groove 12 of the tension member 14 of the optical cable 101 shown in FIG. Further, the optical cable 102 shown in FIG. 6 is an example in which a core wire movement preventing material 192 made of a buffer material is inserted into the groove 12 of the tension member 14 of the optical cable 101 shown in FIG. Examples of the fibrous buffer material that fills the grooves 12 include polyester fibers such as polyethylene terephthalate fibers, aramid fibers such as poly-p-phenylene terephthalamide fibers, polyarylate fibers, and polyparaphenylene benzbisoxazole fibers. Examples thereof include fibers such as polyamide fibers (nylon fibers), yarns and strings made of these fibers, and split yarns and strings made of polypropylene. These fibers, yarns, strings, etc. may be adhered or impregnated with water-absorbing resin particles. If such fibers, yarns, etc. are used, water running in the cable due to water immersion should be avoided. Can be prevented.

  In the present invention, for example, as shown in FIG. 7, the number of single-core optical fibers 17 may be two or more. The optical cable 104 shown in FIG. 7 has two single-core optical fibers 16 arranged in the above embodiment.

  For example, as shown in FIGS. 8 to 10, one or more optical fiber ribbons 161 and 162 may be used instead of the single-fiber ribbon 16. An optical cable 105 shown in FIG. 8 is a two-core light in which two optical fiber single-core wires are arranged in parallel instead of one single-fiber optical fiber 16 and the outer periphery thereof is collectively covered in the above embodiment. One fiber ribbon 161 is disposed. In the optical cable 106 shown in FIG. 9, in the above embodiment, instead of one single-core optical fiber 16, four optical fiber single-core wires are arranged in parallel, and the outer periphery thereof is collectively covered 4 One optical fiber tape core 162 is disposed. Further, the optical cable 107 shown in FIG. 10 is formed by laminating two similar four-fiber optical fiber ribbons 162 in the above embodiment. It is.

  Next, examples of the present invention will be described, but the present invention is not limited to the following examples.

Example 1
An optical cable 101 having the structure shown in FIG. 1 was manufactured.
As shown in FIG. 15, an outer diameter (D) provided with a groove 12 having a width (a) of 0.4 mm and a depth (b) of 0.6 mm is outside the groove 12 of a tension member 14 made of stretched polyethylene terephthalate having a diameter of 1.1 mm. While inserting a single optical fiber core wire 16 having a diameter of 0.25 mm, support wires 22 having an outer diameter of 1.2 mm are arranged in parallel as shown in FIG. 1 and introduced into an extruder. An optical cable having a cross section of the support wire portion 20 and the cable portion 10 having outer diameters of about 2.2 mm and about 2.1 mm and a cable height of about 4.5 mm was manufactured by batch extrusion coating.

Examples 2-4
The optical cable shown in FIGS. 7 to 9 was manufactured in the same manner as Example 1.
In Example 2, the groove 12 having a width (a) of 0.6 mm and a depth (b) of 0.7 mm provided in the tension member 14 having an outer diameter (D) of 1.2 mm was used in Example 1. Two single-core optical fibers 16 having the same outer diameter of 0.25 mm were inserted. The outer diameter of the cable portion 10 of the obtained optical cable was about 2.2 mm, and the cable height was about 4.6 mm.
In Example 3, the groove 12 having a width (a) of 0.8 mm and a depth (b) of 0.7 mm provided in the tension member 14 having an outer diameter (D) of 1.4 mm has a width of 0.6 mm and a thickness. One 0.3 mm two-core optical fiber ribbon 161 was inserted. The outer diameter of the cable portion 10 of the obtained optical cable was about 2.4 mm, and the cable height was about 4.7 mm.
Further, in Example 4, the groove 12 having a width (a) of 1.3 mm and a depth (b) of 1.1 mm provided in the tension member 14 having an outer diameter (D) of 2.0 mm has a width of 1.1 mm and a thickness. One 0.3 mm four-core optical fiber ribbon 162 was inserted. The outer diameter of the cable portion 10 of the obtained optical cable was about 3.0 mm, and the cable height was about 5.5 mm.

  When the support line part 20 was separated from each obtained optical cable and the wiring work of the cable part 10 was tried, all the cable parts 10 can be bent almost freely in any direction, and the wiring work should be performed smoothly. I was able to.

Table 1 shows the outer diameter (D) and material of the tension member 14 used in each example, the width (a) and depth (b) of the groove 12, the bending rigidity (M) in the depth direction of the groove, The bending stiffness (N) in the direction orthogonal to the depth direction, the ratio of these bending stiffnesses (M / N), the type of optical fiber core used, and the number of housings are shown. Table 1 also shows a conventional type optical drop cable and an optical indoor cable in which two strength members are embedded in the jacket for comparison. The bending rigidity of the comparative example shown in Table 1 is measured by regarding the arrow direction in FIG. 16B as a direction orthogonal to the depth direction of the groove. This table also shows that the optical cable according to the example is excellent in wiring workability.

It is sectional drawing which shows one Embodiment of the optical cable of this invention. It is a figure which shows typically the example of installation of the optical cable shown in FIG. It is sectional drawing which shows isolation | separation of the support line part from the optical cable shown in FIG. FIG. 2 is a cross-sectional view showing the entry of a cicada oviduct in the optical cable shown in FIG. It is sectional drawing which shows the modification of the optical cable shown in FIG. It is sectional drawing which shows the other modification of the optical cable shown in FIG. It is sectional drawing which shows other embodiment of the optical cable of this invention. It is sectional drawing which shows other embodiment of the optical cable of this invention. It is sectional drawing which shows other embodiment of the optical cable of this invention. It is sectional drawing which shows other embodiment of the optical cable of this invention. It is sectional drawing explaining the tension member used for this invention. It is sectional drawing which shows an example of the conventional optical cable.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Cable part, 12 ... Groove, 14 ... Tension member, 16 ... Single core optical fiber, 18 ... Outer sheath, 20 ... Support line part, 22 ... Support line, 24 ... Cover | cover, 30 ... Connection part 101- 107 : Optical cable, 161, 162 ... Optical fiber ribbon, 191, 192 ... Core wire movement prevention material

Claims (4)

An optical cable having a cable part and a support line part that supports the cable part,
The cable portion includes a tension member having a U-shaped or V-shaped groove extending in a longitudinal direction on a tensile strength wire having a circular cross section, an optical fiber core housed in the groove, and an outer periphery thereof. Provided with a jacket having a circular cross section provided,
The groove of the tension member has an opening on the support line portion side, and is formed in a size and shape so that the optical fiber core wire can freely rotate without deforming the outer shape in the groove. optical cable and said that you are.   The tension member has a bending rigidity (M) in the depth direction of the groove of 4900 MPa or less, and a bending rigidity (N) in the direction perpendicular to the depth direction of the groove and the bending rigidity (N) in the depth direction of the groove. The optical cable according to claim 1, wherein a ratio (M / N) with respect to () is 1.0 or more and 2.0 or less.   3. The optical cable according to claim 1, wherein the groove is formed in a size and shape so that the optical fiber core wire to be accommodated is accommodated at substantially the center of the tensile strength line.   The core wire movement prevention material which prevents the movement of the radial direction of an optical fiber core wire is inserted in the groove | channel in which the optical fiber core wire was accommodated, The any one of Claim 1 thru | or 3 characterized by the above-mentioned. Optical cable.

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