JP2003337267A - Optical fiber cable - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical fiber cable whose manufacturing cost is suppressed to be low and which can improve the workability at the laying time or the like. <P>SOLUTION: This optical fiber cable 1 is provided with a slot 3 where a spiral groove 4 is formed at the outer circumference of a long body whose cross section is almost circular, a plurality of ribbons of coated optical fibers 10 formed by being integrally covered with a connection resin coating layer 11 while a plurality of optical fiber wires 12 are arranged in parallel with one another, stacked and housed within the groove 4, a pressing winding 7 provided so as to cover the circumference of the slot 3, and an outer coating layer 8 covering the outer side of the pressing winding 7. When the number of the ribbons of coated optical fibers 10 stacked inside one groove 4 is defined as n, the thickness of the ribbons of optical fibers 10 as Tt, the depth of the groove 4 as Ds, the width of the groove 4 as Ws, and the outer diameter of the slot 3 as D, the cross section shape of the groove 4 satisfies the following relation expression: n×Tt≤Ds≤n×Tt+(1/2) D (1-cos(sin<SP>-1</SP>(Ws/D))). <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical fiber cable, and more specifically, to a slot in which a spiral groove is formed, a plurality of tape-type optical fiber cores stacked in the groove, and the periphery of the slot. The present invention relates to an optical fiber cable including a press winding that covers the press winding and a jacket layer that is coated on the outside of the press winding.

[0002]

2. Description of the Related Art In recent years, as the demand for optical communication systems has increased, optical fiber cables, which are optical transmission lines, are often installed in pipelines and outdoor racks. Generally, a tape slot type optical fiber cable as shown in FIG. 12 is widely used as an optical fiber cable laid on a trunk route for communication such as a pipeline or an outdoor rack.

As shown in FIG. 12, in a conventional tape slot type optical fiber cable 50, a plurality of tape type optical fiber core wires 60 are housed in a groove 53 of a slot 52 having a tension member 51 at the center. . The optical fiber cable 50 is a 100-fiber type optical cable, and
Five tape-type optical fiber core wires 60 each having four cores are laminated in each of the three grooves 53. Also, the five grooves 53
Are formed in a unidirectional spiral shape in parallel with each other along the longitudinal direction. Further, in order to prevent the tape type optical fiber core wire 60 from coming off the groove 53, the slot 52
A press winding 54 is wound around the. Further, the outer surface of the press winding 54 is covered with a plastic outer cover layer 55.

The tension member 51 is a tensile strength member provided to prevent the tension from being directly transmitted to the tape type optical fiber core wire 60 when tension is applied to the optical fiber cable 50, for example, a diameter. A 1.8 mm steel wire is used. Further, for example, the outer diameter of the slot 52 is 8 mm, and the pitch of the groove 53 is 500 mm.

The tape-type optical fiber core wire 60 is thinner than usual in order to increase the density. The outer shape is, for example, 0.32 mm in thickness and 1.1 mm in width.
Is. The five tape-type optical fiber core wires 60 housed in one groove 53 are stacked in a state of closely adhering to each other in the thickness direction, and the tape-type optical fiber core wire 60 housed in the innermost side is the groove. It is in contact with the bottom surface of 53. On the other hand, the tape type optical fiber core wire 60 housed on the outermost side is arranged at a position having a desired distance from the opening end of the groove 53 so as not to come into contact with the press winding 54. That is, the depth of the groove 53 is formed so as to be larger than the height at which the five tape type optical fiber core wires 60 are stacked by a desired length. For example, a space is provided between the outermost tape type optical fiber core wire 60 and the press winding 54 to accommodate at least one tape type optical fiber core wire 60.

The optical fiber cable 50 thus constructed has, for example, an outer diameter of 12 mm and a weight of 114 kg / k.
m.

[0007]

By the way, since the optical fiber cable 50 described above uses the slot in which the spiral groove is formed, it is difficult to suppress the manufacturing cost in manufacturing the optical fiber cable. In addition, when the optical fiber cable 50 is wound around a bobbin or laid in a conduit or the like, it is difficult to obtain good workability due to the diameter and weight.

An object of the present invention is to provide an optical fiber cable which can be manufactured at a low cost and can be improved in workability during installation.

[0009]

An optical fiber cable according to the present invention for achieving the above object comprises a slot having a spiral groove formed on the outer periphery of an elongated body having a substantially circular cross section,
A plurality of tape type optical fiber core wires, which are integrally covered with resin in a state in which a plurality of optical fiber element wires are arranged in parallel with each other and are stacked and housed in a groove, and the periphery of the slot are covered. The number of tape-type optical fiber cores laminated in one groove is n, and the number of tape-type optical fiber cores When the thickness is Tt, the depth of the groove is Ds, the width of the groove is Ws, and the outer diameter of the slot is D, the cross-sectional shape of the groove is: n · Tt ≦ Ds ≦ n · Tt + (1/2) D [1-cos
The relational expression of {sin ⁻¹ (Ws / D)}] is satisfied.

According to the optical fiber cable having such a structure, the depth of the groove of the slot becomes smaller than that of the conventional one. As a result, the diameter of the slot can be reduced and the optical fiber cable can be reduced in diameter. Therefore, the manufacturing cost of the optical fiber cable can be kept low. Further, since the weight of the optical fiber cable can be reduced, good workability can be obtained when the optical fiber cable is laid in a conduit. Furthermore, even if the optical fiber cable is in a straight line state, the tape-type optical fiber core wire laminated in the groove and the press winding are likely to come into contact with each other. Therefore, the friction resistance of the tape-type optical fiber core wire increases, and the movement of the tape-type optical fiber core wire in the groove can be prevented.

In order to achieve the above object, the optical fiber cable according to the present invention has a slot in which a spiral groove is formed on the outer periphery of an elongated body having a substantially circular cross section, and a plurality of optical fiber strands. A plurality of tape-type optical fiber core wires that are integrally covered with resin in a state where they are arranged in parallel with each other and are stacked and housed in a groove, and a press winding provided so as to cover the periphery of the slot. And the outer coating layer coated on the outer side of the press winding, and the spiral pitch P of the groove when the outer diameter of the slot is D satisfies the relational expression of π · D / tan2 ° ≦ P .

According to the optical fiber cable having such a structure, the spiral pitch of the groove becomes longer than that of the conventional one. Therefore, it is possible to increase the linear velocity when the slot is extruded and when the tape type optical fiber core wire is housed in the groove. Therefore, the manufacturing cost of the optical fiber cable can be kept low. In addition, as the spiral pitch of the groove becomes longer, the inclination angle of the groove in the axial direction of the slot becomes smaller. Therefore, the wall thickness provided between the grooves of the slot should be smaller than that when the inclination angle is large. It is possible to reduce the diameter of the slot. Therefore, workability when laying an optical fiber cable can be improved.

In order to achieve the above object, the optical fiber cable according to the present invention has a slot having spiral grooves formed on the outer periphery of an elongated body having a substantially circular cross section, and a plurality of optical fiber strands. A plurality of tape-type optical fiber core wires that are integrally covered with resin in a state where they are arranged in parallel with each other and are stacked and housed in a groove, and a press winding provided so as to cover the periphery of the slot. And a coating layer coated on the outer side of the press winding, and the thickness of the coating in the laminating direction of the tape-type optical fiber core made of resin is 5 to 25 μm.

According to the optical fiber cable having such a configuration, the thickness of the tape type optical fiber core wire becomes thinner than that of the conventional one, so that the groove depth of the slot can be made shallow. As a result, the diameter of the slot can be reduced and the optical fiber cable can be reduced in diameter. Therefore, the manufacturing cost of the optical fiber cable can be kept low. Further, since the weight of the slot and the weight of the tape type optical fiber core can be reduced respectively, workability at the time of laying can be improved.

The optical fiber cable according to the present invention for achieving the above object has a slot having a spiral groove formed on the outer periphery of an elongated body having a substantially circular cross section, and a plurality of optical fiber strands. A plurality of tape-type optical fiber core wires that are integrally covered with resin in a state where they are arranged in parallel with each other and are stacked and housed in a groove, and a press winding provided so as to cover the periphery of the slot. And a covering layer coated on the outside of the press winding, the number of tape-type optical fiber cores laminated in one groove is n, the thickness of the tape-type optical fiber core is Tt, and the thickness of the groove is Depth is Ds and groove width is W
s and the outer diameter of the slot are D, the cross-sectional shape of the groove is: n · Tt ≦ Ds ≦ n · Tt + (1/2) D [1-cos
{Sin ⁻¹ (Ws / D)}] and the spiral pitch P of the groove satisfies the relational expression of π · D / tan2 ° ≦ P 2.

The optical fiber cable according to the present invention for achieving the above object has a slot in which a spiral groove is formed on the outer periphery of an elongated body having a substantially circular cross section, and a plurality of optical fiber strands. A plurality of tape-type optical fiber core wires that are integrally covered with resin in a state where they are arranged in parallel with each other and are stacked and housed in a groove, and a press winding provided so as to cover the periphery of the slot. And a covering layer coated on the outside of the press winding, the number of tape-type optical fiber cores laminated in one groove is n, the thickness of the tape-type optical fiber core is Tt, and the thickness of the groove is Depth is Ds and groove width is W
s and the outer diameter of the slot are D, the cross-sectional shape of the groove is: n · Tt ≦ Ds ≦ n · Tt + (1/2) D [1-cos
{Sin ⁻¹ (Ws / D)}] and the coating thickness of the tape-type optical fiber core made of resin is 5 in the stacking direction.
Is about 25 μm.

The optical fiber cable according to the present invention for achieving the above object has a slot in which a spiral groove is formed on the outer periphery of an elongated body having a substantially circular cross section, and a plurality of optical fiber strands. A plurality of tape-type optical fiber core wires that are integrally covered with resin in a state where they are arranged in parallel with each other and are stacked and housed in a groove, and a press winding provided so as to cover the periphery of the slot. And a jacket layer coated on the outer side of the press winding, where the outer diameter of the slot is D, the spiral pitch P of the groove satisfies the relational expression of π · D / tan2 ° ≦ P, and The coating thickness of the tape type optical fiber core made of resin is 5 in the stacking direction.
Is about 25 μm.

In order to achieve the above object, the optical fiber cable according to the present invention has a slot in which a spiral groove is formed on the outer circumference of an elongated body having a substantially circular cross section, and a plurality of optical fiber strands. A plurality of tape-type optical fiber core wires that are integrally covered with resin in a state where they are arranged in parallel with each other and are stacked and housed in a groove, and a press winding provided so as to cover the periphery of the slot. And a covering layer coated on the outside of the press winding, the number of tape-type optical fiber cores laminated in one groove is n, the thickness of the tape-type optical fiber core is Tt, and the thickness of the groove is Depth is Ds and groove width is W
s and the outer diameter of the slot are D, the cross-sectional shape of the groove is: n · Tt ≦ Ds ≦ n · Tt + (1/2) D [1-cos
{Sin ⁻¹ (Ws / D)}] and the spiral pitch P of the groove satisfies the relational expression of π · D / tan2 ° ≦ P, and further, the tape mold formed of resin The thickness of the coating in the stacking direction of the optical fiber core wire is 5 to 25 μm.

Further, the width of the tape type optical fiber core wire is set to Wt.
It is desirable that the cross-sectional shape of the groove at that time satisfies the relational expression of Wt + 0.05 ≦ Ws.

The optical fiber element has a wavelength of 1.55 μm.
m has a mode field diameter of 8 μm or less according to the definition of Petermann-I, a cable cutoff wavelength of 1.26 μm or less, and a wavelength of 1.55 μm measured by a wire mesh bobbin method.
It is desirable that the microbend loss in 0.1 is 0.1 dB / km or less.

The optical fiber element has a wavelength of 1.55 μm.
m has a mode field diameter of 8 μm or less according to the definition of Petermann-I, a cable cutoff wavelength of 1.26 μm or less, and a proof level of 1.5% or more. It is desirable that the optical fiber strand is a through-fiber.

The optical fiber has a wavelength of 1.55 μm.
m has a mode field diameter of 8 μm or less according to the definition of Petermann-I, a cable cutoff wavelength of 1.26 μm or less, and a wavelength of 1.55 μm measured by a wire mesh bobbin method.
It is desirable that the optical fiber strand has a microbend loss of 0.1 dB / km or less and a proof level of 1.5% or more and has undergone a tensile strength test.

The optical fiber has a bending diameter of 20 m.
Bending loss at a wavelength of 1.55 μm at mφ of 0.1d
It is preferably B / m or less.

Further, the fatigue coefficient n of the optical fiber strand is 5
It is preferably 0 or more.

Further, it is desirable that the optical fiber element wire is provided with a coating film having a water blocking property on the outer periphery of the cladding region. Titanium or carbon can be used as the material of the coating film.

It is desirable that the optical fiber strand is an optical fiber strand that has been subjected to a tensile strength test with a proof level of 2.0% or more.

Further, it is desirable that the outer diameter of the cladding region of the optical fiber element wire is 60 to 100 μm.

Further, in the optical fiber element wire, it is desirable that the thickness of the coating layer provided around the cladding region is 37.5 μm or less.

In the optical fiber element, the coating layer other than the colored layer provided around the cladding region is formed into two layers, an inner layer and an outer layer, and the Young's modulus of the inner layer is 2MP.
It is preferably a or less and the outer layer has a Young's modulus of 98 MPa or more.

In the optical fiber element wire, a single coating layer other than the colored layer provided around the cladding region is formed, and the Young's modulus of the coating layer is preferably 98 MPa or more.

[0031]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of an optical fiber cable according to the present invention will be described below with reference to FIGS.
FIG. 1 is a sectional view showing the optical fiber cable of the present embodiment. 2 is a perspective view showing the slot in FIG. 1,
3 is a side view of the slot shown in FIG. 4 is a cross-sectional view of a main part showing the minimum height of the groove in FIG. 1, and FIG. 5 is a cross-sectional view of the main part showing the maximum height of the groove in FIG. FIG. 6 is a cross-sectional view of the tape type optical fiber core wire in FIG. 1, and FIG. 7 is a cross-sectional view of the optical fiber element wire in FIG. 6 and a diagram showing a refractive index distribution.

As shown in FIG. 1, the optical fiber cable 1 of this embodiment is a unidirectionally twisted tape slot type optical fiber cable using a slot 3 having a unidirectionally twisted groove as a cable core. The slot 3 is provided with a tension member 2 at the center, and five grooves 4 are spirally formed in the outer peripheral portion (see FIG. 2).
In each groove 4, five tape-type optical fiber core wires 10 each having four cores are stacked and housed. Therefore, the optical fiber cable 1 is a 100-core type cable. Five tape-type optical fiber core wires 10 housed in one groove 4
Are stacked in close contact with each other in the thickness direction,
The tape type optical fiber core wire 10 housed in the innermost side is in contact with the bottom surface of the groove 4. Further, in order to prevent the tape type optical fiber core wire 10 from coming off from the groove 4, a press winding 7 is wound around the slot 3. Furthermore, the outer side of the press winding 7 is covered with a plastic outer coat layer 8.

As shown in FIGS. 2 and 3, the outer peripheral portion of the slot 3 has a spiral shape having a constant inclination angle θ with respect to the axis with the five grooves 4 being parallel to each other along the longitudinal direction. Is formed in. Here, when the outer diameter of the slot 3 is D, the spiral pitch P of the groove 4 is obtained by P = π · D / tan θ (1). The spiral pitch P of this embodiment is formed so that the inclination angle θ is smaller than 2 °.
That is, the spiral pitch P obtained by the above equation (1)
Satisfies the relational expression of π · D / tan2 ° ≦ P (2). The spiral pitch P defined by the equation (2) is longer than the spiral pitch in the conventional groove. For example, the outer diameter D of the slot 3 is 6.6 m.
m, and the spiral pitch P of the groove 4 is 1000 mm.

As described above, by making the inclination angle θ smaller and making the spiral pitch P longer than in the conventional groove, the tape type optical fiber core wire 10 is assembled in the groove 4 at the time of extrusion molding. The linear velocity when storing can be increased. If the inclination angle θ is small, the slot 3
Since the stress in the circumferential direction applied to the groove 4 during extrusion molding becomes small, it is possible to prevent the shape of the slot 3 from being distorted. Therefore, the wall thickness provided between the grooves 4 of the slot 3 can be made smaller than that when the inclination angle θ is large, and the diameter of the slot 3 can be reduced. Further, when the tape-type optical fiber core wire 10 is assembled in the groove 4, the stress in the cross-sectional direction applied to the tape-type optical fiber core wire 10 due to the contact with the groove 4 becomes small, so that the tape-type optical fiber core wire is reduced. The line 10 can be prevented from being damaged.

As shown in FIGS. 4 and 5, the cross-sectional shape of the groove 4 is approximately the depth Ds (mm) of the groove and the width Ws (mm) of the groove.
Represented by and. Here, the number of the tape type optical fiber cores 10 laminated in one groove 4 is n, the thickness of the tape type optical fiber cores 10 is Tt (mm), and the outer diameter of the slot is D (mm). Then, the depth Ds of the groove is expressed by the following relational expression: n · Tt ≦ Ds ≦ n · Tt + (1/2) D [1-cos {sin ⁻¹ (Ws / D)}] (3) It is set to meet.

The depth D of the groove set by the above equation (3)
The state when s is the minimum is shown in FIG. At this time,
The depth Ds of the groove is equal to that of the laminated tape-type optical fiber core wire 1
The height n · Tt is 0, and the press winding 7 and the outermost tape type optical fiber core wire 10 are
It is in contact with a wide area. In this embodiment,
The depth Ds of the groove 4 and the height n · Tt of the tape type optical fiber core wire 10 are both 1.3 mm.

FIG. 5 shows a state in which the groove depth Ds set by the above equation (3) is maximum. At this time, the depth Ds of the groove is (1/2) D [1-cos from the height n · Tt of the laminated tape type optical fiber cores 10.
{Sin ^-1 (Ws / D)}] (hereinafter referred to as A) is deepened. It should be noted that the depth A is determined by the press winding 7 in the groove 4
This is a value that represents the depth of slack inward, and is a value that matches the distance from the arc 3a on the outer peripheral line of the slot 3 to the opening end 4a of the groove 4. The press winding 7 is slightly loosened in the groove 4, and the press winding 7 is in contact with the outermost tape type optical fiber core wire 10.

Further, in FIGS. 4 and 5, when the width of the tape type optical fiber core wire 10 is Wt (mm), the width Ws of the groove is Wt + 0.05≤Ws (4) Is set to meet. Preferably,
A gap of 0.025 mm or more is preferably provided on both sides in the width direction of the tape type optical fiber core wire 10 housed in the groove 4. In the present embodiment, the tape type optical fiber core wire 1
The width Wt of 0 is 1.1 mm and the width Ws of the groove 4 is 1.2 mm.

By setting the cross-sectional shape of the groove 4 as described above, even if the optical fiber cable 1 is in a straight line state, the tape type optical fiber core wire 10 and the press winding 7 laminated in the groove 4 It is in constant contact. Therefore, it is possible to prevent the tape-type optical fiber core wire 10 from moving in the groove 4 due to frictional resistance generated between the tape-type optical fiber core wire 10 and the press winding 7.
Further, since the depth of the groove 4 is shallower than in the conventional case, the diameter of the slot 3 can be reduced and the diameter of the optical fiber cable 1 can be reduced.

The tape type optical fiber core wire 10 housed in the groove 4 will be described with reference to FIG. The tape-type optical fiber core wire 10 includes four optical fiber element wires 12 obtained by coating a glass optical fiber with an ultraviolet curable resin.
Are arranged in contact in a horizontal row, and the whole is covered with the connecting resin coating layer 11 to form a tape.
Usually, a urethane acrylate-based UV curable resin is used for the connecting resin coating layer 11. Tape-type optical fiber core wire 10 formed by the connecting resin coating layer 11
The thickness d of the coating in the stacking direction is set to 5 to 25 μm. The thickness d of the coating here is half the length of the thickness Tt of the tape-type optical fiber core wire 10 minus the outer diameter of the optical fiber element wire 12. Further, the outer shape of the tape-type optical fiber core wire 10 has a thickness Tt of 0.26.
mm, and the width Wt is 1.1 mm. Thus, the depth of the groove 4 can be made shallow by using the tape-type optical fiber core wire 10 having a thickness Wt smaller than that of the conventional one.
Further, instead of making the depth of the groove 4 shallow, it is also possible to stack and store a large number of tape type optical fiber core wires 10 in the groove 4.

As described above, the optical fiber cable 1 of this embodiment can be made thinner and lighter than the conventional one. For example, the outer diameter of the optical fiber cable 1 is 1
The weight is 0.6 mm and the weight is 92 kg / km. Further, by reducing the diameter of the slot 3, the amount of resin used for manufacturing the slot 3 is reduced, and the optical fiber cable 1
The manufacturing cost of can be kept low. Furthermore, as the diameter and weight of the optical fiber cable 1 are reduced,
Good workability can be obtained when the optical fiber cable 1 is laid in a conduit.

Next, the optical fiber element wire 12 used for the tape type optical fiber core wire 10 of the optical fiber cable 1 will be described with reference to FIG. FIG. 7A shows a sectional view when the optical fiber element wire 12 is cut along a plane perpendicular to the optical axis, and FIG. 7B shows a refractive index profile of the optical fiber element wire 12. The optical fiber strand 12 has a core region 13 having an outer diameter d ₁₃ including the center of the optical axis, a clad region 14 having an outer diameter d ₁₄ surrounding the core region 13, and a carbon layer 15 surrounding the clad region 14. A coating layer 16 having an outer diameter d ₁₆ surrounding the carbon layer 15 is provided. A colored layer may be coated around the coating layer 16.

The core region 13 and the cladding region 14 use quartz glass (SiO ₂ ) as a host material.
Both or one of the core region 13 and the cladding region 14 contains an additive for adjusting the refractive index. Then, the refractive index n ₁ of the core region 13 is
Is higher than the refractive index n ₂ . Preferably, the core region 13 has a substantially unimodal refractive index profile and the cladding region 14 has a substantially constant refractive index. In this case,
The optical fiber strand 1 has a simple refractive index profile.
2 is easy to manufacture.

The "substantially unimodal" core region 13
The refractive index distribution of includes the ideal step shape as shown in FIG. 7B, a shape in which the refractive index increases toward the central portion of the core, or a substantially step shape, but the refractive index in the vicinity of the periphery is Includes a shape that is slightly higher, a shape that is a substantially step shape, but has a gradually decreasing refractive index in the vicinity of the periphery, and the like.

Preferably, for example, the core region 13 is made of quartz glass doped with germanium oxide (GeO ₂ ), and the cladding region 14 is made of quartz glass doped with fluorine (F). Alternatively, the core region 13 is GeO ₂ -doped silica glass and the cladding region 14 is substantially pure silica glass. The core region 13 may contain another refractive index raising agent, and the cladding region 14 may contain another refractive index lowering agent. By containing such an additive for adjusting the refractive index, the optical fiber element wire 12 can obtain a desired refractive index profile.

The carbon layer 15 is a coating film of amorphous carbon coated around the cladding region 14, and its thickness is about 0.04 μm. As this coating method, it is known that a CVD method in which a raw material gas is chemically reacted with the surface of an optical fiber of a drawn glass body to deposit amorphous carbon is advantageous in terms of film formation speed and film quality. . The optical fiber in which the glass layer is coated with the carbon layer in this manner is called carbon-coated fiber (CCF) and has a high water impermeability. Therefore, the cladding region 14
Water can be prevented from entering the core region 13 from the outside, and the optical transmission characteristics of the optical fiber element wire 12 can be guaranteed at a high level. Further, since the fatigue coefficient n of CCF is 100 or more, and in some cases 200 or more, it is possible to prevent the fracture life from being shortened when stress such as bending is applied. Further, instead of using the carbon layer 15, it is possible to use a titanium coating film. In that case, high water impermeability is obtained and the fatigue coefficient n is 50
The above can be done.

In general, the outer diameter d ₁₄ of the cladding region 14 of the optical fiber element wire 12 is 125 μm, and the outer diameter d ₁₆ of the coating layer ₁₆ is 250 μm. However, the outer diameter d ₁₄ of the cladding region 14 is preferably 60 to 100 μm. In this case, when the optical fiber element wire 12 is bent into a small diameter, the probability of breakage due to bending strain is reduced,
Long-term reliability is improved. Moreover, the thickness of the coating layer 16 is preferably 37.5 μm or less. In this case, since the outer shape of the tape-type optical fiber core wire 10 can be reduced, the optical fiber cable 1 can be reduced in diameter.
Alternatively, the number of optical fiber wires 12 to be stored can be increased.

The coating layer 16 includes the inner layer 16a and the outer layer 1.
6b may be formed in two layers. In that case, it is desirable that the Young's modulus of the inner layer 16a is 2 MPa or less and the Young's modulus of the outer layer 16b is 98 MPa or more. With such a configuration, the inner layer 16a serves as a buffer layer against lateral pressure, and microbends are less likely to occur in the optical fiber element wire 12, so that high optical transmission characteristics can be maintained.

When the coating layer 16 is a single layer, its Young's modulus is preferably 98 MPa or more. With such a configuration, it is not necessary to prepare two kinds of resins used as the coating layer. Therefore, material management becomes easier,
Manufacturing costs can be kept low. Further, since the facility for coating the resin can also have a simple structure, the manufacturing cost can be reduced in terms of facility cost.
Further, the deformation of the coating layer 16 when the optical fiber element wire 12 is wound around a bobbin or the like can be reduced, and the frictional resistance between the optical fiber element wires 12 is reduced. Therefore, it is possible to prevent the optical fiber strands 12 from being entangled with each other when unwound from the bobbin.

The optical fiber 12 has a mode field diameter (MFD) of 8 according to the definition of Petermann-I at a wavelength of 1.55 μm.
μm or less. Here, the mode field diameter defined by Petermann-I is

[0051]

[Equation 1]

It is defined by the following equation. The variable r in this equation (5) is the radial distance from the optical axis of the optical fiber element wire 12. φ (r) is the electric field distribution of light in the radial direction,
It depends on the wavelength of light. By reducing the mode field diameter, microbending loss and bending loss (macrobending loss) can be reduced. Therefore, for example, when the spiral pitch P of the groove 4 of the optical fiber cable 1 is increased, even if the optical fiber element wire 12 is easily distorted, an increase in transmission loss of the optical fiber element wire 12 is suppressed. be able to.

The optical fiber strand 12 has a wavelength of 1.3.
The mode field diameter defined by Petermann-I in μm is preferably 6 μm or more. In this case, the optical fiber element wire 12 has a small splice loss when fusion-spliced with a standard single-mode optical fiber having a zero-dispersion wavelength in the 1.3 μm wavelength band. Further, even when such optical fiber strands 12 are fusion-spliced, the connection loss due to the axis deviation is small.

The cable cutoff wavelength of the optical fiber element wire 12 is 1.26 μm or less. The cable cutoff wavelength is the LP ₁₁ mode cutoff wavelength at a length of 22 m, and is a value smaller than the 2 m cutoff wavelength.

Further, the optical fiber element wire 12 has a microbend loss of 0.1 dB / km or less at a wavelength of 1.55 μm measured by the wire mesh bobbin method. In the wire mesh bobbin method, for example, a wire having an outer diameter of 50 μm is pitched 15 on the entire body surface of a bobbin having a body diameter of about 400 mm.
Stick a wire mesh woven in a grid pattern with 0 μm, and on the outer periphery,
The amount of increase in transmission loss is measured when an optical fiber strand is wound around only one layer with a tension of about 0.8N. This makes it possible to suppress an increase in transmission loss even in a state where microbends are likely to occur in the optical fiber strand 12 due to the environment in which the optical fiber cable 1 is installed. Further, even if the inner wall of the groove 4 or the press winding 7 is in contact with the tape type optical fiber core wire 10 in the groove 4 of the slot 3, it is possible to prevent the transmission loss from increasing.

As the optical fiber strand 12, it is preferable to use an optical fiber strand that has been subjected to a tensile strength test with a proof level of 1.5% or more. The proof here is a guarantee of the strength of the optical fiber strand to be commercialized, and before winding the drawn optical fiber strand around a bobbin,
A tensile strength test is performed by providing a tension application section on the running line. That is, the elongation rate (%) of the optical fiber strand can be set as the proof level by setting the tension applied to the tension application section to an arbitrary value. As a result, it is possible to break the low-strength optical fiber element wire that does not reach the desired proof level, and wind only the unbroken part on a bobbin or the like to obtain a product.

The breaking strength of the optical fiber strand can be represented by a Weibull distribution (not shown) having the breaking strength (N) and the cumulative breaking probability (%) as variables. 1.
Optical fiber strands that meet the proof level of 5% are 50
The cumulative probability of breakage is extremely low even when N tension is applied. In a normal laying environment of an optical fiber cable, the tension applied to the optical fiber element wire 12 is estimated to be 50 N or less. Therefore, by performing a tensile strength test that defines a proof level of 1.5% or more, It is possible to prevent the mechanical strength of the optical fiber strand 12 from being lowered due to the installation environment. Therefore, it is not necessary to increase the tensile strength of the optical fiber cable 1 more than necessary. For example, as the tension member 2, it is possible to use a steel wire having a diameter of 1.2 mm, which is smaller than the conventional one.

As the optical fiber strand 12, it is more preferable to use an optical fiber strand that has been subjected to a tensile strength test with a proof level of 2.0% or more. Further, when the proof level is 3.0% or more and 4.0% or more, the optical fiber element wire 12 having very good mechanical strength can be used for the optical fiber cable 1.

The optical fiber wire 12 has a bending diameter of 2
The bending loss (macrobend loss) at a wavelength of 1.55 μm at 0 mmφ is 0.1 dB / m or less. Therefore, when the optical fiber cable 1 is laid in a conduit or the like, the increase amount of the transmission loss of the optical fiber wire 12 can be reduced, and sufficiently practical transmission characteristics can be obtained. Further, the optical fiber element wire 12 preferably has a bending loss of 0.1 dB / m or less at a bending diameter of 15 mmφ and a wavelength of 1.55 μm. In addition, the optical fiber strand 12 is
It is more preferable that the bending loss at a bending diameter of 10 mmφ and a wavelength of 1.55 μm is 0.1 dB / m or less. Thus, if the bending loss characteristics of the optical fiber element wire 12 are good, bending loss is unlikely to occur even when the optical fiber element wire 12 is bent with a small bending diameter due to the laying environment of the optical fiber cable 1. Therefore, it is possible to prevent an increase in transmission loss and guarantee the quality of the optical fiber strand 12 at a high level.

As described above, the optical fiber element wire 12 used in the optical fiber cable 1 of the present embodiment can exhibit good optical transmission characteristics even when lateral pressure, bending, pulling or the like is added. . Therefore, in the optical fiber cable 1, not only is the diameter of the optical fiber cable 1 reduced due to the structural characteristics of the slot 3 and the workability thereof is improved, but also the characteristics of the optical fiber wire 12 allow reliable and high quality optical transmission. You can get the road effectively.

The optical fiber cable according to the present invention is not limited to the above embodiment. For example, a high-density mounting type optical fiber cable such as a 200-core type, a 400-core type, or a 1000-core type can be used.

As shown in FIG. 8, the optical fiber cable 20 according to the first modification of the above embodiment is a 200-fiber type optical fiber cable. This optical fiber cable 20
Is a slot 22 having a tension member 21 in the center
In each of the ten grooves 23, five tape type optical fiber cores 10 are stacked and housed. The groove 23 has the same form as the groove 4 (see FIG. 4). The tape-type optical fiber core wire 10 has the same configuration and characteristics as the tape-type optical fiber core wire 10 used in the above-mentioned optical fiber cable 1.

Further, the four-core tape type optical fiber core wire 10
It is also possible to use a taper optical fiber core having a larger number of fibers. For example, it is possible to use a tape type optical fiber core wire such as 8 cores, 12 cores, 24 cores or 36 cores. As shown in FIG. 9, an eight-core tape-type optical fiber core wire 10a is obtained by arranging eight optical fiber wires 12 described above in parallel and integrally covering them with a connecting resin coating layer 11a.
The tape-type optical fiber core wire 10a has a coating thickness d of 5 to 25 μm, similar to the tape-type optical fiber core wire 10.
Is set to. In addition, the tape type optical fiber core wire 10
The outer diameter of a is, for example, 0.26 mm in thickness and 2. Wt is 2.
It is 2 mm.

As shown in FIG. 10, a 400-core type optical fiber cable 30 using the above-mentioned tape-type optical fiber core wire 10a of 8 cores is provided in five grooves 33 of a slot 32 having a tension member 31 at the center. , 10 tape-type optical fiber cores 10a are stacked and housed. The groove 33 is formed so as to satisfy the above formulas (2), (3) and (4).

Further, as shown in FIG. 11, a 1000-core type optical fiber cable 40 using the eight-core tape-type optical fiber core wire 10a has a tension member 41 at the center.
1 in each of the 12 grooves 43 of the slot 42 having
Zero tape type optical fiber cores 10a are stacked and stored. Further, the slot 42 is formed with one groove 43a having a depth almost half that of the groove 43, and five tape type optical fiber core wires 10a are formed in the groove 43a.
Are stacked and stored. The grooves 43 and 43a are formed so as to satisfy the above expressions (2), (3), and (4), respectively.

Each of the above-mentioned optical fiber cables 20, 3
Nos. 0 and 40 can reduce the manufacturing cost by reducing the diameter and the weight more than the optical fiber cable 10 or more. Further, it is possible to improve workability at the time of laying.

[0067]

As described above, according to the optical fiber cable of the present invention, the shape of the groove is defined to reduce the diameter of the slot, and the pitch of the groove is defined to reduce the weight of the optical fiber cable. By doing so, the manufacturing cost can be kept low and the workability at the time of laying can be improved.
Further, by reducing the thickness of the tape-type optical fiber core wire housed in the groove of the slot, the diameter of the optical fiber cable can be reduced.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of an optical fiber cable according to the present invention.

FIG. 2 is a perspective view showing a slot in FIG.

3 is a side view of the slot shown in FIG. 2. FIG.

FIG. 4 is a cross-sectional view of an essential part showing the minimum height of a groove in FIG.

5 is a cross-sectional view of an essential part showing the maximum height of the groove in FIG.

6 is a cross-sectional view of the tape-type optical fiber core wire in FIG.

7A and 7B are a cross-sectional view and a refractive index distribution of the optical fiber strand shown in FIG.

8 is a cross-sectional view showing a first modification of the optical fiber cable shown in FIG.

9 is a cross-sectional view showing a modified example of the tape type optical fiber core wire shown in FIG.

10 is a sectional view showing a second modification of the optical fiber cable shown in FIG.

11 is a cross-sectional view showing a third modification of the optical fiber cable shown in FIG.

FIG. 12 is a cross-sectional view showing an example of a conventional optical fiber cable.

[Explanation of symbols]

1 optical fiber cable 2 tension members 3 slots 4 grooves 7 holding roll 8 outer layer 10 Tape type optical fiber core 11 Connection resin coating layer (resin) 12 Optical fiber strand 13 core area 14 Clad area 15 Carbon layer (coating film) 16 coating layer Outer diameter of D slot Ds groove depth n Number of laminated tape-type optical fiber cores P groove spiral pitch Thickness of Tt tape type optical fiber Ws groove width Wt Tape type optical fiber core width Angle of θ groove

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Itaru Sakabe             Sumitomoden 1 Taya-cho, Sakae-ku, Yokohama-shi, Kanagawa             Ki Industry Co., Ltd. Yokohama Works (72) Inventor Kazuaki Hamada             Sumitomoden 1 Taya-cho, Sakae-ku, Yokohama-shi, Kanagawa             Ki Industry Co., Ltd. Yokohama Works F term (reference) 2H001 BB09 BB16 DD04 DD09 DD24                       KK12 KK17 PP01

Claims (20)

[Claims] 1. A slot in which a spiral groove is formed on the outer circumference of an elongated body having a substantially circular cross section and a plurality of optical fiber element wires are arranged in parallel with each other and integrally covered with a resin. A plurality of tape-type optical fiber core wires that are stacked and housed in the groove, a press winding provided so as to cover the periphery of the slot, and an outer coating layer that is coated on the outside of the press winding. And n is the number of the tape type optical fiber cores laminated in the one groove, and T is the thickness of the tape type optical fiber cores.
where t is the depth of the groove, Ds is the width of the groove, and D is the outer diameter of the slot, the cross-sectional shape of the groove is n · Tt ≦ Ds ≦ n · Tt + (1/2) D [1-cos
An optical fiber cable that satisfies the relational expression of {sin ⁻¹ (Ws / D)}. 2. A slot in which a spiral groove is formed on the outer periphery of an elongated body having a substantially circular cross section and a plurality of optical fiber element wires arranged in parallel with each other are integrally covered with a resin. A plurality of tape-type optical fiber core wires that are stacked and housed in the groove, a press winding provided so as to cover the periphery of the slot, and an outer coating layer that is coated on the outside of the press winding. And an outer diameter of the slot is D, a spiral pitch P of the groove satisfies a relational expression of π · D / tan2 ° ≦ P. 3. A slot in which a spiral groove is formed on the outer periphery of an elongated body having a substantially circular cross section and a plurality of optical fiber element wires are arranged in parallel with each other and integrally covered with resin. A plurality of tape-type optical fiber core wires that are stacked and housed in the groove, a press winding provided so as to cover the periphery of the slot, and an outer coating layer that is coated on the outside of the press winding. And a coating thickness in the stacking direction of the tape type optical fiber core wire formed of the resin is 5 to 25 μm. 4. A slot in which a spiral groove is formed on the outer periphery of an elongated body having a substantially circular cross section and a plurality of optical fiber element wires are arranged in parallel with each other and integrally covered with resin. A plurality of tape-type optical fiber core wires that are stacked and housed in the groove, a press winding provided so as to cover the periphery of the slot, and an outer coating layer that is coated on the outside of the press winding. And n is the number of the tape type optical fiber cores laminated in the one groove, and T is the thickness of the tape type optical fiber cores.
where t is the depth of the groove, Ds is the width of the groove, and D is the outer diameter of the slot, the cross-sectional shape of the groove is n · Tt ≦ Ds ≦ n · Tt + (1/2) D [1-cos
{Sin ⁻¹ (Ws / D)}], and the spiral pitch P of the groove satisfies the relational expression of π · D / tan2 ° ≦ P. . 5. A slot in which a spiral groove is formed on the outer circumference of an elongated body having a substantially circular cross section and a plurality of optical fiber element wires are arranged in parallel with each other and are integrally covered with a resin. A plurality of tape-type optical fiber core wires that are stacked and housed in the groove, a press winding provided so as to cover the periphery of the slot, and an outer coating layer that is coated on the outside of the press winding. And n is the number of the tape type optical fiber cores laminated in the one groove, and T is the thickness of the tape type optical fiber cores.
where t is the depth of the groove, Ds is the width of the groove, and D is the outer diameter of the slot, the cross-sectional shape of the groove is n · Tt ≦ Ds ≦ n · Tt + (1/2) D [1-cos
{Sin ⁻¹ (Ws / D)}], and the coating thickness of the tape type optical fiber core made of the resin in the laminating direction is 5 to 25 μm. Characteristic optical fiber cable. 6. A slot in which a spiral groove is formed on the outer periphery of an elongated body having a substantially circular cross section and a plurality of optical fiber element wires are arranged in parallel with each other and integrally covered with a resin. A plurality of tape-type optical fiber core wires that are stacked and housed in the groove, a press winding provided so as to cover the periphery of the slot, and an outer coating layer that is coated on the outside of the press winding. And the outer diameter of the slot is D, the spiral pitch P of the groove satisfies the relational expression of π · D / tan2 ° ≦ P, and the tape-shaped light formed by the resin. The optical fiber cable, wherein the coating thickness of the fiber core wire in the stacking direction is 5 to 25 μm. 7. A slot in which a spiral groove is formed on the outer periphery of an elongated body having a substantially circular cross section and a plurality of optical fiber element wires arranged in parallel with each other are integrally covered with a resin. A plurality of tape-type optical fiber core wires that are stacked and housed in the groove, a press winding provided so as to cover the periphery of the slot, and an outer coating layer that is coated on the outside of the press winding. And n is the number of the tape type optical fiber cores laminated in the one groove, and T is the thickness of the tape type optical fiber cores.
where t is the depth of the groove, Ds is the width of the groove, and D is the outer diameter of the slot, the cross-sectional shape of the groove is n · Tt ≦ Ds ≦ n · Tt + (1/2) D [1-cos
{Sin ⁻¹ (Ws / D)}], and the spiral pitch P of the groove satisfies the relational expression of π · D / tan2 ° ≦ P, and further, it is formed by the resin. The optical fiber cable, wherein the coating thickness of the tape-type optical fiber core wire in the stacking direction is 5 to 25 μm. 8. The optical fiber cable according to claim 1, wherein when the width of the tape type optical fiber core wire is Wt,
The optical fiber cable, wherein the cross-sectional shape of the groove satisfies a relational expression of Wt + 0.05 ≦ Ws. 9. The optical fiber cable according to claim 1, wherein the optical fiber strand has a mode field diameter defined by Petermann-I at a wavelength of 1.55 μm. Is 8 μm or less, the cable cutoff wavelength is 1.26 μm or less, and the microbend loss at a wavelength of 1.55 μm measured by the wire mesh bobbin method is 0.1 dB / km or less. Fiber cable. 10. The optical fiber cable according to claim 1, wherein the optical fiber strand has a mode field diameter according to the definition of Petermann-I at a wavelength of 1.55 μm. Is 8 μm or less, the cable cut-off wavelength is 1.26 μm or less, and the optical fiber cable has been subjected to a tensile strength test with a proof level of 1.5% or more. 11. The optical fiber cable according to claim 1, wherein the optical fiber strand has a mode field diameter defined by Petermann-I at a wavelength of 1.55 μm. Is 8 μm or less, the cable cutoff wavelength is 1.26 μm or less, and the microbend loss at a wavelength of 1.55 μm measured by the wire mesh bobbin method is 0.1 dB / km or less, and
An optical fiber cable, which is an optical fiber element wire that has been subjected to a tensile strength test with a proof level of 1.5% or more. 12. The optical fiber cable according to any one of claims 9 to 11, wherein the optical fiber has a bending loss of 0.1 dB / m or less at a wavelength of 1.55 μm at a bending diameter of 20 mmφ. An optical fiber cable characterized by being present. 13. The optical fiber cable according to claim 9, wherein the optical fiber has a fatigue coefficient n of 50 or more. 14. The optical fiber cable according to claim 13, wherein the optical fiber element is provided with a water-shielding coating film on the outer periphery of the cladding region. 15. The optical fiber cable according to claim 14, wherein the coating film is made of carbon. 16. The optical fiber cable according to claim 9, wherein the optical fiber wire is an optical fiber wire that has been subjected to a tensile strength test with a proof level of 2.0% or more. An optical fiber cable characterized in that 17. The optical fiber cable according to claim 9, wherein the optical fiber has a cladding region having an outer diameter of 60 to 1.
An optical fiber cable having a thickness of 00 μm. 18. The optical fiber cable according to any one of claims 9 to 11, wherein the coating layer provided around the cladding region of the optical fiber element wire has a thickness of 37.5 μm or less. An optical fiber cable characterized in that 19. The optical fiber cable according to any one of claims 9 to 11, wherein the optical fiber element has an inner layer and an outer layer which are coating layers other than the colored layer provided around the cladding region. The optical fiber cable is formed of two layers, the Young's modulus of the inner layer is 2 MPa or less, and the Young's modulus of the outer layer is 98 MPa or more. 20. The optical fiber cable according to any one of claims 9 to 11, wherein the optical fiber element wire has a single coating layer other than a colored layer provided around the cladding region. And the Young's modulus of the coating layer is 98 MPa or more.