JP2965550B2 - Optical cable and spacer for optical cable - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an optical cable laid on land, aerial or under the sea, and a spacer used for mounting an optical fiber on the optical cable.

[0002]

2. Description of the Related Art Conventionally, techniques in such a field include:
One disclosed in Japanese Patent Application Laid-Open No. 55-45087 is known. The optical cable described in this publication is
A plastic spacer having a fiber housing for accommodating an optical fiber core, a pipe core, a tape core, and the like (hereinafter, collectively simply referred to as “optical fiber”), and a tension serving as a core member. And members. The spacers accommodating the optical fibers are assembled around the core member with the bottom surface in contact with the core member. Each spacer has a bottom wall and a pair of side walls rising from both ends of the bottom wall. That is, the spacer has a substantially U-shaped cross-sectional shape. Further, the spacer is extruded as one straight elongated member. The thickness of the bottom wall and the side wall of the spacer is preferably 0.5 mm or more.

Japanese Patent Application Laid-Open No. 4-182611 discloses a spacer having a substantially U-shaped cross section accommodating an optical fiber, which is curved along the outer peripheral surface of a core member, and assembled in an SZ twist around the core member. An optical cable is described. In this case, as shown in FIG. 18, the spacers 100 are assembled around the core member 110 with the bottom surface in contact with the core member 110 so that the fiber housing portion 102 faces outward. . Therefore, in the SZ trajectory formed by the spacer 100, the S twist is changed to the Z twist, or
At the position Re where the twist is reversed to the S twist (hereinafter referred to as “SZ inversion portion”, see FIG. 19), as shown in FIG.
The spacer 100 needs to be curved in the width direction x of the fiber container 102. On the other hand, at an intermediate position between adjacent SZ inversion portions (hereinafter, referred to as “SZ transition portion”), the spacer 100 needs to be curved in the depth direction y of the fiber housing portion 102 as shown in FIG.

[0004]

However, the conventional optical cable and spacer have the following problems. That is, when a spacer having a fiber housing portion having a width longer than its depth is used, and such a wide spacer is gathered around the core member in an SZ twist, the spacer is bent in the width direction x at the SZ inversion portion Re. Shoulder spacer (see Fig. 20)
May be curved in the depth direction y (see FIG. 21 or FIG. 22). In this case, the spacer is twisted, and as shown in FIGS. 23 and 24, the side surface of the spacer comes into contact with the core member, so that the fiber housing portion does not correctly face outward (hereinafter, this state is referred to as “falling down”. ").

[0005] On the other hand, when a spacer in which the depth of the fiber accommodating portion is longer than its width is used and such vertically elongated spacers are assembled in a SZ twist around the core member, the depth is set at the SZ transition portion. In some cases, a spacer (see FIG. 21 or 22) to be bent in the direction y is bent in the width direction x (see FIG. 20). Also in this case, the spacer is twisted, and as shown in FIGS. 23 and 24, the side surface is in contact with the core member, so that the fiber accommodating portion does not correctly face outward.

In any case, in a state where the spacer has fallen, the side surface of the spacer comes into contact with the core member, so that the fiber accommodating portion does not correctly face outward. And the optical fiber accommodated in the fiber accommodating part of the spacer is also twisted together with the spacer. As a result, a so-called microbend may occur in the optical fiber, and transmission loss may increase. Further, when the spacer has fallen, it is difficult to take out the optical fiber when performing the so-called intermediate post-branch, in which the optical fiber is taken out from the optical cable after the optical cable is laid, and the workability is reduced.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem, and an optical cable having excellent transmission characteristics and excellent optical fiber take-out characteristics, in which the spacer is hardly inclined at both the SZ inversion portion and the SZ transition portion. It is another object of the present invention to provide an optical cable spacer applied to the optical cable.

[0008]

According to a first aspect of the present invention, there is provided an optical cable comprising: a spacer having a fiber housing portion for housing an optical fiber; and a core member for twisting the spacer. In an optical cable having an SZ twisted region in which a spacer accommodating the fiber is assembled in an SZ twist around the core member, the spacer has a flexural rigidity in the depth direction of the fiber accommodating portion that is greater than a flexural rigidity in the width direction of the fiber accommodating portion. Also has small characteristics, and SZ
Of the strain energy of the spacer in the SZ inversion portion in the twist region, the strain energy when the bottom surface of the spacer is in contact with the core member is U _1, and the strain energy when the side surface of the spacer is in contact with the core member is U _{1 When 2} , it satisfies ΔU = U ₁ −U ₂ ≦ 0.2 (mJ / mm).

When an optical cable having a region in which a plurality of spacers are gathered in an SZ twist around a core member is configured,
In the entire SZ locus formed by the spacer, the bottom surface of the spacer must be reliably brought into contact with the core member, and the fiber housing portion must be kept correctly oriented outward. For this purpose, it is necessary to curve the spacer in the depth direction along the outer peripheral surface of the core member at the SZ transition portion of the SZ locus formed by the spacer. For example, a spacer in which the depth of the fiber housing is longer than its width is more stable in the state of being bent in the width direction than in the state of being bent in the depth direction. Therefore, in order to make the spacer easily bendable in the width direction, the bending rigidity in the depth direction of the fiber housing portion of the spacer is
It is necessary to make it smaller than the bending rigidity in the width direction.

On the other hand, in the SZ reversal portion of the SZ locus formed by the spacer, the spacer must be curved in the width direction. For example, a spacer in which the width of the fiber housing portion is longer than its depth is more stable in the state of being bent in the depth direction than in the state of being bent in the width direction. Therefore, to make the spacer easy to bend in the depth direction,
The bending stiffness in the depth direction needs to be smaller than the bending stiffness in the width direction. In other words, in both the SZ inversion section and the SZ transition section, it is not enough to consider the bending rigidity of the spacer in order to prevent the spacer from falling down.

[0011] Based on these matters, the present inventors have:
In order to prevent the spacer from falling down in the SZ inversion section and the SZ transition section, intensive studies have been made. In the course of research, the present inventors paid attention to the distortion energy of the spacer in the SZ inversion portion (energy stored in the spacer when the spacer is bent in a certain direction). That is, the bottom surface of the spacer is in contact with the core member, the strain energy of the state where the fiber containing cavity is correctly facing away and U _1, the side surface of the spacer is in contact with the core member, the strain energy in a state where the spacer is lying focusing on the relationship between the two in the case of the U _2. Then, an experiment for repeatedly examining the relationship between the difference ΔU = U ₁ −U _{2 of} the strain energy and the incidence rate of the spacer falling down was repeated. As a result, the inventors have found that the bending stiffness of the spacer in the depth direction of the fiber housing portion is smaller than the bending stiffness in the width direction of the fiber housing portion, and that the difference in strain energy ΔU is equal to 0.
It has been found that when it is 2 mJ / mm or less, the rate of occurrence of spacer collapse is reduced, and practically excellent results are obtained.

As described above, by making the flexural rigidity in the depth direction of the spacer smaller than the flexural rigidity in the width direction, the spacer can be easily curved in the depth direction at the SZ transition portion of the SZ locus. Therefore, in this optical cable, the state where the fiber housing portion of the spacer faces outward at the SZ transition portion of the SZ locus can be reliably maintained. On the other hand, the difference ΔU of the strain energy is 0.2 mJ / mm.
By doing so, it is possible to reliably maintain the state in which the fiber housing portion faces outward even in the SZ reversal portion of the SZ locus where the spacer is curved in the width direction.

In this case, the spacer is made of PBT resin and HD
The spacer is preferably formed of a mixed resin with a PE resin, and the spacer is preferably formed of a mixed resin of a PC / PBT resin and an HDPE resin.

The present inventors have also conducted intensive research on the material of the spacer used for the optical cable in order to prevent the spacer from collapsing at the SZ inversion portion and the SZ transition portion. Also, when selecting the material for forming the spacer used in the optical cable, it is necessary to consider physical properties such as impact resistance, rigidity and strength, and environmental resistance such as low-temperature embrittlement and stress tracking. There is. In view of these matters, the present inventors have repeatedly conducted experiments on various materials in order to find an optimum material for forming a spacer used in an optical cable. And, as a material for forming the spacer, P
Mixed resin of BT resin and HDPE resin or PC / PBT
It has been found that practically extremely good results can be obtained by using a mixed resin of a resin (a blend of a PBT resin and a polycarbonate resin) and an HDPE resin.

That is, the spacer is made of PBT resin or PBT.
When the spacer is formed of C / PBT resin, the rigidity of the spacer itself becomes unnecessarily large. Such a spacer is called S
When curved in the width direction at the Z inversion portion, the side surface of the spacer comes into contact with the core member, and the fiber housing portion does not correctly face outward.
When an optical cable is laid in an environment where the ambient temperature changes greatly, the HDPE resin may recrystallize inside the spacer formed by the HDPE resin. In this case, the spacer contracts in the longitudinal direction, and the SZ inversion angle and the SZ twist pitch are disturbed.

On the other hand, if the spacer is made of PBT resin or a resin obtained by mixing PC resin / PBT resin and HDPE resin, the spacer can have appropriate flexibility while maintaining the rigidity of the spacer. Becomes Also, even if the HDPE resin is recrystallized due to a change in ambient temperature,
Since the PBT resin or the PC resin / PBT resin has sufficient rigidity, shrinkage of the spacer is suppressed to a minimum.

Further, the proportion of the HDPE resin in the mixed resin is preferably 20 to 80% by volume. Thereby, it is possible to extremely effectively suppress the shrinkage of the spacer due to the change in the ambient temperature while maintaining the rigidity of the spacer.

On the other hand, the spacer preferably has a bottom wall and a pair of side walls rising from both ends of the bottom wall, and the fiber accommodating portion is preferably formed by the bottom wall and the side walls.
Thereby, since the spacer has a substantially U-shaped cross section,
Various optical fibers such as an optical fiber core, a pipe core, and a tape core can be housed in the fiber housing part.

Preferably, the spacer further includes a tensile member provided at a central portion in the width direction of the bottom wall.
This makes it possible to impart tensile strength to the spacer without unnecessarily increasing the bending rigidity in the width direction of the spacer. Accordingly, when the spacers are assembled on the core member, even if tension is applied to the spacers, the optical fibers will not be distorted. As a result, an optical cable can be manufactured while maintaining the reliability of the optical fiber.

Further, it is preferable that the tensile strength member is arranged with its central axis close to the bottom surface. That is, the tensile strength member is arranged such that its central axis is located closer to the bottom surface of the spacer than the center line between the inner surface of the bottom wall and the outer surface of the bottom wall (the bottom surface of the spacer). In general, when a strength member is provided on the bottom wall of a spacer used for an optical cable, the strength member is introduced into a die, and a molten resin is extruded from a die together with the strength member. When the extruded resin cures,
The amount of shrinkage in the depth direction of the resin forming the bottom wall of the spacer differs between the portion where the tensile strength member exists and the other portion. That is, the shrinkage of the resin at the portion where the tensile strength member is present is smaller than the shrinkage of the resin at the other portions. As a result, the bottom surface of the fiber container, that is,
Unevenness occurs on the inner surface of the bottom wall.

Here, when bending or pulling force is applied to the optical cable, a force toward the central axis of the optical cable acts on the optical fiber housed in the fiber housing portion of the spacer. Then, the optical fiber is pressed against the bottom surface of the fiber container. At this time, if the bottom surface of the fiber housing portion has irregularities, the optical fiber 7 bends along the irregularities, and so-called microbending occurs. As a result, the transmission characteristics of the optical cable deteriorate. The thickness of the bottom wall of the spacer is very thin (about 0.4 to 1.5 mm). The strength member also has a certain thickness. Therefore, the influence of the unevenness existing on the bottom surface of the fiber housing on the transmission characteristics of the optical cable cannot be ignored. This is an important problem particularly in an optical cable having a large number of optical fibers and a small diameter.

On the other hand, if the strength member is arranged with respect to the spacer with its central axis being close to the bottom surface of the spacer, the amount of resin shrinkage at the portion where the strength member exists and the other portions can be reduced. The occurrence of the irregularities caused by the difference from the amount of resin shrinkage can be reduced. This eliminates the need to remove the generated irregularities by, for example, a cutting tool, or to smooth the surface by pressing a heated flat plate or roller. Therefore, the spacer used for the optical cable can be produced economically without increasing the number of manufacturing steps. Further, when the spacer is formed of a thermoplastic resin, it is not necessary to add an inorganic substance or the like which may impair the smoothness of the fiber housing portion to the thermoplastic resin.

Further, it is preferable that the tensile strength member is arranged in a state close to the bottom surface. That is, the strength member is disposed such that the entire strength member is located on the bottom surface side of the spacer with respect to the center line between the inner surface of the bottom wall and the outer surface of the bottom wall (the bottom surface of the spacer). Accordingly, the strength member is further away from the bottom surface (the inner surface of the bottom wall) of the fiber housing portion, so that the occurrence of unevenness can be suppressed very effectively. In this case, the strength member may be partially exposed from the bottom surface (outer surface of the bottom wall) of the spacer.

According to a ninth aspect of the present invention, an optical cable spacer according to the present invention has a fiber housing portion for housing an optical fiber, and can be twisted around a core member of the optical cable. The SZ inversion portion in the SZ region in which the bending rigidity in the depth direction of the fiber housing portion is smaller than the bending rigidity in the width direction of the fiber housing portion, and is assembled in an SZ twist around the core member. When the strain energy when the bottom surface is in contact with the core member is U ₁ and the strain energy when the side surface is in contact with the core member is U ₂ , △ U = U ₁ −U ₂ ≤ 0.2 (mJ / m
m).

By adopting such a configuration, when the spacers are assembled in an SZ twist around the core member, the SZ locus of the SZ locus in which the spacers are curved in the width direction.
The reversing section can maintain the state where the fiber housing section faces outward. Further, at the SZ transition portion of the SZ locus, the spacer is curved in the depth direction, but also in this case, the state where the fiber housing portion faces outward can be maintained.

The bottom and side walls of the spacer are formed of PBT.
It is preferable that the spacer and the bottom wall and the side wall of the spacer be made of PC / PBT.
The resin and the HDPE resin may be integrally molded with a mixed resin. Further, the ratio of the HDPE resin in the mixed resin is preferably set to 20 to 80% by volume.

On the other hand, the spacer preferably has a bottom wall and a pair of side walls rising from both ends of the bottom wall, and the fiber accommodating portion is preferably formed by the bottom wall and the side walls.
Further, it is preferable that a strength member provided at a central portion in the width direction of the spacer bottom wall be provided. Further, the strength member is preferably arranged with its central axis close to the bottom surface, and the strength member is preferably arranged with the center axis close to the bottom surface.

[0028]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of an optical cable and an optical cable spacer according to the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a sectional view showing an optical cable according to the present invention. FIG. 2 is a perspective view showing an optical cable according to the present invention. As shown in FIG. 1, a long cylindrical member (central tensile member) 2 serving as a core member of the optical cable 1 is disposed at the center of the optical cable 1.
This cylindrical member 2 is formed of a synthetic resin,
It has a diameter of 25 mm. In the center of the columnar member 2, one steel stranded wire 3 is embedded. This steel stranded wire 3 is one in which seven steel wires having a diameter of 2.0 mm are stranded together. The outer surface of the cylindrical member 2 is provided with a fiber housing 10a.
Are assembled in an SZ twist (see FIG. 2). In this optical cable 1, fifteen spacers 10 are formed with SZ twist pitch P (adjacent SZ inversion portion Re).
Twice the distance between 1 and Re2) is 600 mm, and S
The Z inversion angle φ is set as 275 °.

When assembling the optical cable, each spacer 10 is curved along the outer peripheral surface of the cylindrical member 2. The bottom surface of the spacer 10 is in contact with the outer peripheral surface of the columnar member 2, and the fiber accommodating portion 10a faces outward. A plurality of (for example, 10) tape cores (optical fibers) 5 are stacked in the fiber housing portion 10a. A pressing tape 6 such as a nonwoven fabric is wound around the spacers 10 gathered in the SZ twist without gaps. A jacket 7 made of low-density polyethylene is further provided around the holding tape 6 to protect the inside of the optical cable 1.

The spacer 10 is manufactured as a single straight elongated member. As shown in FIG. 3, the spacer 10 includes a bottom wall 12 and a pair of side walls 11 rising from both ends of the bottom wall 12. Fiber housing 10a
Is created by the bottom wall 12 and the side wall 11. Thereby, the spacer 10 has a substantially U-shaped cross section. Various optical fibers such as an optical fiber core, a pipe core, and a tape core can be housed in the fiber housing part 10a.

One strength member 8 is incorporated in the bottom wall 12 of the spacer 10 at the center in the width direction x of the fiber accommodating portion 10a. This makes it possible to provide the spacer 10 with tensile strength without unnecessarily increasing the bending rigidity of the spacer 10 in the width direction x. Therefore, when the spacers 10 are assembled on the columnar member 2, even if tension is applied to the spacers 10, no distortion occurs in the tape core wire 5. As a result, the optical cable 1 can be manufactured while maintaining the reliability of the optical fiber. As a material of the tensile strength member 8, an aromatic polyamide fiber (manufactured by DuPont, trade name: Kevlar), FRP, glass fiber, or the like is preferable.

Each dimension of the spacer 10 is Bu = 6.
6 mm, bu = 4.6 mm, Bl = 5.0 mm, bl =
3.5 mm, D = 5.0 mm, d = 4.5 mm, T =
1.0 mm and t = 0.5 mm. In determining these dimensions, the design was performed while taking the following points into consideration. First, when the spacers 10 are assembled in an SZ twist around the cylindrical member 2 of the optical cable 1, an SZ transition portion Tr of the SZ locus formed by the spacer 10 (see FIG. 2, an intermediate portion between the adjacent SZ inversion portions Re 1 and Re 2). At the position), the spacer 10 is curved with the smallest radius of curvature. Also in this case, the spacer bottom surface 12a of the spacer 10
Must be surely in contact with the columnar member 2 and the state where the fiber housing portion 10a faces outward. Therefore, the bending rigidity in the depth direction y is
Spacer 10
Was configured.

That is, in the spacer 10, the bending rigidity EI ₁ in the depth direction y of the fiber housing portion 10a is:
It is 9.11 × 10 ⁴ (N · mm ² ). On the other hand, the bending rigidity EI ₂ in the width direction x of the fiber housing portion 10a is 1.06 × 10 ⁵ (N · mm ² ). That is, less than the stiffness EI ₂ bending in the bending rigidity EI ₁ is the widthwise direction x in the depth direction y. Accordingly, in the optical cable 1 in which the spacers 10 are gathered around the cylindrical member 2 in an SZ twist, the SZ transition portion Tr in which the spacers 10 are curved in the depth direction y with the smallest radius of curvature.
Thus, it is possible to maintain the state where the fiber housing portion 10a faces outward.

In the SZ reversal portion Re (see FIG. 2) of the SZ locus formed by the spacer 10, it is necessary to curve the spacer 10 in the width direction x. Here, in the spacer 10 in which the bending stiffness in the depth direction y is smaller than the bending stiffness in the width direction x, the state of bending in the depth direction y is more stable than the state of bending in the width direction x. doing.
Therefore, unless any countermeasure is taken, the spacer 10 to be bent in the width direction x in the SZ inversion portion Re is bent in the depth direction y and the spacer 10 falls down. In order to solve this problem, the present inventors have conducted intensive research, and during the course of the research, the present inventors have found that the SZ trajectory formed by the spacers 10 in the region where the spacers 10 are gathered in an SZ twist. Of the spacer 10 in the SZ inversion portion (energy stored in the spacer when the spacer 10 is bent in a certain direction).

That is, the spacer bottom 1 of the spacer 10
2a comes into contact with (outsides) the cylindrical member 2, and the fiber housing portion 1
0a is the strain energy of the condition being correctly facing away and U _1, spacer side 11a is in contact with the cylindrical member 2 (contact outside), both in the case of the strain energy in a state where the spacer 10 is fallen and U ₂ We focused on the relationship. And
An experiment for repeatedly examining the relationship between the strain energy difference ΔU = U ₁ −U ₂ , that is, the difference between the strain energies before and after the spacer 10 collapses and the incidence rate of the spacer 10 collapse is repeated. Was. In this experiment, a plurality of spacers having different structures were prototyped, and the spacers were assembled on a cylindrical member at different pitches in an SZ twist. In each case, the relationship between the difference ΔU in the strain energy and the occurrence rate of the spacer collapse was examined by visually checking the collapse of the spacer in the SZ inversion portion Re.

In this experiment, the spacer 10 shown in FIG.
The spacer 20 shown in FIG. 4, the spacer 30 shown in FIG. 5, the spacer 40 shown in FIG. 6, and the spacer 50 shown in FIG.
Was used. Here, the spacer 20 of FIG.
In this embodiment, one strength member 8 is built in the center in the width direction x. Each dimension of the spacer 20 is B = 6.
6 mm, b = 4.6 mm, D = 5.0 mm, T = 1.0
mm, t = 0.5 mm. As the tensile member 8, 1
140 denier aromatic polyamide fiber is used.

The spacer 30 shown in FIG. 5 has no built-in strength member in the bottom wall 32. Instead, one strength member 8 is incorporated in each of the side walls 31 of the spacer 30 at the center in the depth direction y. Spacer 3
0 are the same as those of the spacer 20 shown in FIG.
6.6 mm, b = 4.6 mm, D = 5.0 mm, T =
1.0 mm and t = 0.5 mm. As the tensile member 8, 1140 denier aromatic polyamide fiber is used. On the other hand, the spacer 40 shown in FIG. 6 has no built-in strength member in either the side wall 41 or the bottom wall 42. Each dimension of the spacer 40 is B = 5.6 mm, b = 4.6 mm,
D = 5.0 mm, T = 0.5 mm, and t = 0.5 mm.

The spacer shown in FIG. 7 has one strength member 8 built-in at the center of the bottom wall 52 in the width direction x. As the tensile member 8, 195 denier aromatic polyamide fiber is used. The dimensions of the spacer 50 are Bu = 6.2 mm, Bu = 4.7 mm, and Bl =
4.7 mm, D = 5.5 mm, d = 4.6 mm, T =
0.8 mm, t = 0.5 mm. The radius of curvature R of the bottom surface of the fiber housing 50a is 1.8 mm. Each of the spacers 20, 30, 40, and 50 described above has a flexural rigidity in the depth direction y of the fiber housing portion.
It has characteristics smaller than the bending stiffness in the width direction x of the fiber housing portion (calculation results are omitted).

In this experiment, the spacers 20, 30,
For 40, a long cylindrical member having a diameter of 25 mm was used as the core member. Twelve spacers were assembled in an SZ twist around the cylindrical member. In this case, the SZ twist pitch P is 400 mm, 500 mm, 6 mm for the spacer 10 shown in FIG. 3 and the spacer 20 shown in FIG.
00 mm, 700 mm and 800 mm. For the spacer 30 shown in FIG.
1000 mm and 1200 mm. For the spacer 40 shown in FIG.
0 mm and 800 mm. Further, the experiment was performed while the reversal angle φ of the SZ twist was kept constant at 275 ° for each spacer.

On the other hand, regarding the spacer 50 shown in FIG. 7, an optical cable 60 (outer diameter 39 mm) as shown in FIG.
Were experimentally manufactured, and the relationship between the strain energy difference ΔU in the optical cable 60 and the incidence rate of the spacer falling was examined.
In the center of the optical cable 60, a long spiral slot 61 serving as a core member is arranged. The spiral slot 61 is formed of a synthetic resin such as an HDPE resin and has a diameter of 20 mm. At the center of the spiral slot 61, one steel stranded wire 62 is embedded. This steel stranded wire 62 is formed by twisting seven steel wires having a diameter of 2 mm into one.

On the outer periphery of the spiral slot 61, ten slots 61a extending in the SZ shape along the longitudinal direction of the spiral slot 61 are formed. Each slot 61
On a, ten tape cores (optical fibers) 5 are laminated. A holding tape 63 such as a nonwoven fabric is wound around the outer peripheral surface of the spiral slot 61 accommodating the tape core wire 5 without any gap. The outer diameter of the spiral slot 61 around which the holding tape 63 was wound was 23.7 mm. Around the holding tape 63, fifteen spacers 50 are assembled in an SZ twist. Ten tape ribbons 5 are stacked in the fiber housing portion 50a of the spacer 50. A presser winding tape 64 is wound around the spacers 50 assembled in the SZ twist without gaps. A 1.5 mm-thick outer cover 65 made of low-density polyethylene is further provided around the holding tape 64. This jacket 65 contains one tearing wire 66. In the experiment, SZ
The reversal angle φ is 275 ° and the SZ twist pitch P is 650 m
m optical cable 60 and SZ twist pitch P is 800 mm
The optical cable 60 was manufactured as a prototype.

Table 1 shows the calculation results of the strain energies U ₁ , U ₂ and ΔU in the SZ inversion portion of each spacer under these conditions. Here, the layer center radius is a, the inversion angle is φ, the SZ twist pitch is P, and the radius of curvature ρ in the SZ inversion portion is ρ = (P / π) ² / ｛2 · a · (π · φ / 180)｝. Then, the Young's modulus is E, the second moment of area is I, the radius of curvature at the SZ inversion is ρ, and the strain energies U ₁ and U ₂ per unit length of the spacer in the SZ inversion are: U = 1 / 2 · Σ (E _i · I _i ) / ρ ² (where i is a suffix indicating the material of the spacer).

The Young's modulus E was measured according to the method specified in JIS K 7127, and the "2.5% modulus value" obtained from the load at 2.5% elongation was adopted. As shown in FIG. 9, the layer center radius a is the bottom wall of the spacers 20 (30, 40, 50) assembled around the core member 2 (61) from the center of the cross section of the core member 2 (61). 22 (32, 4
2, 52) to the center point C. Here, the center point C of the bottom wall is the intersection of the center line between the inner surface and the outer surface of the bottom wall with the axis of symmetry in the width direction of the spacer. Also,
The inversion angle φ is, as shown in FIG. 9, a straight line connecting the center point C1 in the cross section of the spacer at the inversion portion Re1 and the cross-sectional center O of the optical cable, and the inversion portion Re adjacent to the inversion portion Re1.
The angle between the center point C in the cross section of the spacer at 2 and the straight line connecting the cross center O of the two optical cables was used.

[0045]

[Table 1] [Strain energy at the inversion part of each spacer]

Next, the results of the above-described experiment will be described with reference to Table 1. First, the spacer 10 of FIG.
For any SZ twist pitch P, ΔU is 0.2 mJ
/ Mm or less, and no spacer collapse occurred. The following results were obtained for the spacer 20 of FIG. When the SZ twist pitch P is 400 mm, ΔU is equal to 0.
It was 59 mJ / mm, and 30% or more of the spacers fell down in the SZ inversion portion. Also, the SZ twist pitch P is 50
In the case of 0 mm, ΔU is 0.24 mJ / mm, and SZ
Less than 30% of the spacers collapsed at the inverted portion.
Further, when the SZ twist pitch P was 600 mm, 700 mm, and 800 mm, ΔU was 0.2 mJ / mm or less, and no spacer collapse occurred.

With respect to the spacer 30 of FIG. 5, the following results were obtained. If the SZ twist pitch P is 800 mm,
Is 0.37 mJ / mm, and 30% or more of the spacers have fallen in the SZ inversion portion. Also, SZ twist pitch P
Was 900 mm, ΔU was 0.23 mJ / mm, and less than 30% of the entire spacers collapsed at the SZ inversion portion. When the SZ twist pitch P is 1000 mm, △ U
Was 0.15 mJ / mm, and less than 30% of the spacers fell down in the SZ inversion portion. Further, when the SZ twist pitch P is 1200 mm, ΔU is 0.07 mJ / mm.
In this case, no spacer collapse occurred.

The following results were obtained for the spacer 40 shown in FIG. When the SZ twist pitch P is 500 mm,
Was 0.50 mJ / mm, and 30% or more of the spacers fell down in the SZ inversion portion. Also, SZ twist pitch P
Was 600 mm, ΔU was 0.24 mJ / mm, and less than 30% of the entire spacers collapsed at the SZ inversion portion. Further, the SZ twist pitch P is 700 mm and 80 mm.
In the case of 0 mm, ΔU was 0.2 mJ / mm or less, and no spacer collapse occurred. The spacer 50 shown in FIG.
Was 0.2 mJ / mm or less, and no collapse of the spacer occurred.

From this experimental result, the difference in strain energy △
When U satisfies ΔU ≦ 0.2 mJ / mm, the spacer does not fall at the SZ inversion portion at all, or the occurrence rate is such that the spacer can be repaired even if it falls, and is within a practically acceptable range. You can see that. That is, if the optical cable and the spacer are configured so as to satisfy the relational expression of ΔU = U ₁ −U ₂ ≦ 0.2 mJ / mm (1), the bending rigidity in the depth direction is larger than the bending rigidity in the width direction. Even with a small spacer, it is possible to reduce the incidence of the spacer falling in the SZ inversion portion Re. If the optical cable and the spacer are configured based on the relational expression: △ U = U ₁ −U ₂ ≦ 0.1 mJ / mm, it goes without saying that it is more preferable from the experimental results.

Here, when verifying the optical cable 1 shown in FIGS. 1 and 2, among the strain energies of the spacer 10 in the SZ inversion portion Re of the SZ locus formed by the spacer 10, the spacer bottom surface 12a of the spacer 10 is a cylindrical member. The strain energy U _{1 in the} case of being in contact with 2 is U ₁ =
0.83 mJ / mm, whereas spacer 1
The strain energy U ₂ when the 0 side surface 11a is in contact with the columnar member ₂ is U ₂ = 0.71 mJ / mm. That is, since △ U = U ₁ −U ₂ = 0.12 mJ / mm, the condition defined in the above relational expression (1) is satisfied. Therefore, it can be said that this optical cable 1 is an optical cable that hardly causes the spacer to collapse at the SZ inversion portion Re and the SZ transition portion Tr, and has excellent transmission characteristics and optical fiber takeout properties.

Also, when verifying the optical cable 60 shown in FIG. 8, when the inversion pitch P is set to 650 mm and when the inversion pitch P is set to 800 mm, ΔU = U
_{Since 1−} U ₂ = 0.00 mJ / mm, the condition defined by the above relational expression (1) is satisfied. Therefore, it can be said that the optical cable 60 is also an optical cable excellent in transmission characteristics and optical fiber take-out property, in which the spacer does not easily fall at the SZ inversion portion Re and the SZ transition portion Tr.

On the other hand, as a material for forming a spacer conventionally used for an optical cable, PBT resin, PC / PB
T resin, HDPE resin and the like have been used. Where P
When formed of BT resin or PC / PBT resin,
The rigidity of the spacer itself becomes larger than necessary. When such a spacer is curved in the width direction x at the SZ inversion portion Re, the side surface of the spacer is in contact with the core member, and the fiber housing portion does not correctly face outward. When an optical cable is laid in an environment where the ambient temperature changes greatly, the HDPE resin may recrystallize inside the spacer formed by the HDPE resin. In this case, the spacer contracts in the longitudinal direction, and the SZ reversal angle φ and the SZ twist pitch P are disturbed.

Therefore, the present inventors have conducted intensive research on the material of the spacer used for the optical cable in order to prevent the spacer from falling at the SZ inversion portion Re and the SZ transition portion Tr. Here, when selecting a material for forming a spacer used in an optical cable, physical properties such as impact resistance, rigidity and strength, and environmental resistance such as low-temperature embrittlement performance and stress tracking performance are considered. There is a need. The present inventors conducted an experiment described below in order to find an optimum material for forming a spacer used in an optical cable based on these matters.

FIG. 1 is a sectional view of the spacer used in this experiment.
0 is shown. The spacer 70 shown in the figure is manufactured as one straight long member. The spacer 70 is provided on the bottom wall 7.
2 and a pair of side walls 71 rising from both ends of the bottom wall 72.
And has a substantially U-shaped cross-sectional shape. The fiber accommodating portion 70a is created by the bottom wall 72 and the side wall 71. One strength member 73 is provided on the bottom wall 72 of the spacer 70 at the center of the fiber accommodation portion 70a in the width direction x.
Is built-in. The dimensions of the spacer 70 are bu
= 4.6 mm, bl = 3.8 mm, d = 4.7 mm, T
= T = about 1 mm. And the PB with different composition
Using a mixed resin of a T resin and an HDPE resin, and a PC / PBT resin and an HDPE resin whose composition was changed, a plurality of spacers having such a shape were prototyped. The following seven types of spacers were used in the experiment.

[Embodiment 1] The spacer of Embodiment 1 is made of PB
It was formed of a mixed resin of T resin and HDPE resin.
The volume ratio of the HDPE resin in the mixed resin was 70%.

[Embodiment 2] The spacer of the embodiment 2 is made of PB
It was formed of a mixed resin of T resin and HDPE resin.
The volume ratio of the HDPE resin in the mixed resin was 50%.

[Embodiment 3] The spacer of Embodiment 3 is made of PB
It was formed of a mixed resin of T resin and HDPE resin.
The volume ratio of the HDPE resin in the mixed resin was 30%.

Comparative Example 1 The spacer of Comparative Example 1 was made of PB
It was formed of a mixed resin of T resin and HDPE resin.
The volume ratio of the HDPE resin in the mixed resin was 85%.

Comparative Example 2 The spacer of Comparative Example 2 was made of PB
It was formed of a mixed resin of T resin and HDPE resin.
The volume ratio of HDPE resin in the mixed resin was 15%.

Comparative Example 3 The spacer of Comparative Example 3 was HD
It was formed only of PE resin.

Comparative Example 4 The spacer of Comparative Example 4 was made of PB
It was formed only of T resin.

Here, a method of manufacturing the spacer 70 will be briefly described. When molding the spacer 70,
The tensile strength member 73 is sent out to the crosshead die to which the U-shaped die plate is attached, and a mixed resin of PBT resin and HDPE resin, or P
This is performed by extruding a mixed resin of C / PBT resin and HDPE resin. The PBT resin or PC / PBT resin and the HDPE resin are dry-blended by a blender and then supplied to a crosshead die. In this case, PB
When blending the T resin or the PC / PBT resin with the HDPE resin, if an appropriate amount of an additive such as a wax having compatibilizing performance is added, the blending can be performed in a state where both resins are uniformly dispersed.

The heat shrinkage, bending rigidity, and bending buckling diameter of the spacers 70 of the above three examples and four kinds of comparative examples were examined. The results shown in Table 2 below were obtained. . Here, the thermal shrinkage is a shrinkage when a 1 m spacer is left in an atmosphere at 100 ° C. for 1 hour. The bending stiffness is the bending stiffness in the width direction x of the fiber housing portion 70a. The bending buckling diameter is a diameter at which the spacer 70 is bent in the width direction x and the width of the fiber housing portion 71a starts to change.

[0064]

[Table 2]

As shown in Table 1, the spacers of Examples 1 to 3 have a smaller heat shrinkage than the spacers of Comparative Examples 1 and 3. Further, the spacers of Examples 1 to 3 have lower bending rigidity than the spacer of Comparative Example 4. Further, regarding the bending buckling diameter, when the spacer of Comparative Example 4 was bent in the width direction x,
The diameter when the width of the fiber housing portion 71a started to change was as large as 800 mm. In contrast, Examples 1 to 3
Has a small bending buckling diameter of 600 to 700 mm.

Next, an optical cable was prototyped using the spacers of Examples 1 to 3 and Comparative Examples 1 to 4, and the transmission performance of the optical fiber included in the optical cable was measured. The optical cable used in this experiment has the same configuration as the optical cable shown in FIG. A helical slot serving as a core member is arranged in the center of the optical cable. The spiral slot is formed of a synthetic resin such as HDPE resin and has a diameter of 24.5 mm.
On the outer periphery of the spiral slot, along the longitudinal direction, S-Z
Ten slots extending in a shape are formed. In each slot, ten tape ribbons (optical fibers) are stacked. A holding tape such as a nonwoven fabric is wound around the outer peripheral surface of the spiral slot containing the tape core wire without any gap.

Around the holding tape, fifteen spacers of the example and the comparative example accommodating ten 8-core optical fiber tapes (thickness 0.3 mm, width 2.1 mm) were assembled in an SZ twist. . Further, a pressing tape is wound around each spacer without any gap. A jacket 65 made of low-density polyethylene or the like is further provided around the holding tape. The outer diameter of this optical cable is 45 mm. In the experiment, the SZ inversion angle φ was set to 30
The angle was set to 0 °, and an optical cable having an SZ twist pitch P of 450 mm and an optical cable having an SZ twist pitch P of 350 mm were prototyped.

For each optical cable, the transmission performance of the optical fiber housed in each spacer was measured. Further, with respect to the optical cable having the SZ twist pitch P of 350 mm, the transmission loss was measured at a wavelength of 1.55 μm, and after the heat cycle test (−30 ° C. to 70 ° C.) was performed 5 cycles, the transmission characteristics were measured again. The measurement results of this experiment are shown in Table 3 below. As can be seen from the results shown in Table 3, the optical cables using the spacers of Examples 1 to 3 have less transmission loss than the optical cables using the spacers of Comparative Examples 1 to 4. In particular, Comparative Examples 1 to
In the optical cable using No. 4, the transmission loss after the heat cycle test becomes very large. In contrast, Example 1
In the optical cable using the spacers of (1) to (3), the transmission loss hardly changes.

[0069]

[Table 3]

As described above, as a result of this experiment, when a mixed resin of a PBT resin and an HDPE resin is used as a material for forming a spacer used in an optical cable, extremely good results in practice can be obtained. Was found. That is, if a resin in which the PBT resin and the HDPE resin are mixed is used, the spacer can have appropriate flexibility while maintaining the rigidity of the spacer. Also, even if the HDPE resin is recrystallized due to a change in ambient temperature,
Since the PBT resin has sufficient rigidity, the shrinkage of the spacer is minimized.

As can be seen from the results of this experiment, PB
The proportion of the HDPE resin in the mixed resin of the T resin and the HDPE resin is preferably 20 to 80% by volume.
Thereby, it is possible to extremely effectively suppress the shrinkage of the spacer due to the change in the ambient temperature while maintaining the rigidity of the spacer. As a material for forming a spacer used for an optical cable, a PC / PBT resin (PBT resin) is used instead of a mixed resin of a PBT resin and an HDPE resin.
It has been confirmed that even if a mixed resin of a resin and a polycarbonate resin) and an HDPE resin is used, extremely good results in practice can be obtained. Again,
It is preferable that the ratio of the HDPE resin in the mixed resin of the PC / PBT resin and the HDPE resin is 20 to 80% by volume.

In the above experiment, an optical cable was used in which each spacer was assembled in an SZ twist around the outer periphery of the spiral spacer. On the other hand, it has been confirmed that good results can be obtained in the same manner as described above when an optical cable in which spacers such as the optical cable shown in FIG. 1 are assembled around a long cylindrical member is used. I have.

In order to prevent the spacer from falling at the SZ inversion portion Re and the SZ transition portion Tr, it is desirable to provide a tensile member on the bottom wall of the spacer. Here, in general, when a strength member is provided on the bottom wall of a spacer used for an optical cable, the strength member is introduced inside the die, and the molten resin is extruded from the die together with the strength member. When the extruded resin hardens, the amount of shrinkage in the depth direction of the resin forming the bottom wall of the spacer differs between a portion where the tensile strength member is present and another portion. That is, the shrinkage of the resin at the portion where the tensile strength member is present is smaller than the shrinkage of the resin at the other portions.
As a result, irregularities occur on the bottom surface of the fiber housing portion, that is, on the inner surface of the bottom wall.

In the optical cable using the spacer in such a state, when a bending or tensile force is applied to the optical cable, a force toward the central axis of the optical cable acts on the optical fiber housed in the fiber housing portion of the spacer. I do. Then, the optical fiber is pressed against the bottom surface of the fiber container. At this time, if the bottom surface of the fiber housing portion has irregularities, the optical fiber bends along the irregularities, and so-called microbending occurs. As a result, the transmission characteristics of the optical cable deteriorate. The thickness of the bottom wall of the spacer is very thin (about 0.4 to 1.5 mm). The strength member also has a certain thickness. Therefore, the influence of the unevenness existing on the bottom surface of the fiber housing on the transmission characteristics of the optical cable cannot be ignored. This is an important problem particularly in an optical cable having a large number of optical fibers and a small diameter.

Accordingly, the present inventors have conducted intensive studies on the arrangement of the tensile strength members with respect to the spacers, with the main viewpoint of maintaining good transmission characteristics of the optical cable, prototyped various spacers, and manufactured these spacers. An experiment was performed on the used optical cable.

Fourth Embodiment FIG. 11 is a sectional view of a spacer 80A according to a fourth embodiment. The spacer 80A shown in FIG.
It is manufactured as one straight long member. The spacer 80A includes a bottom wall 82A, and a pair of side walls 81A rising from both ends of the bottom wall 82A, and has a substantially U-shaped cross-sectional shape. The fiber housing 84A is created by the bottom wall 82A and the side wall 81A. The dimensions of the spacer 80A are Bl = 7.0 mm, Bl = 5.3 mm, D =
5.2 mm, bu = 4.6 mm, bl = 3.8 mm, d
= 4.7 mm.

Also, on the bottom wall 82A of the spacer 80A,
A tensile strength member 83A is built in a central portion in the width direction x of the fiber housing portion 80a. As the tensile member 83A, one aromatic polyamide fiber of 1140 denier was used. As shown in FIG. 11, the strength axis of the strength member 83A is such that the center axis of the strength member 83A is positioned on the outer surface of the bottom wall 82 (spacer 80).
A (bottom of A) by 0.15 mm. That is, the strength member 83A is arranged with its central axis close to the bottom surface of the spacer 80A. More specifically, the strength member 83 has a central axis
A inner surface and outer surface of bottom wall 82A (bottom surface of spacer 80A)
Are arranged on the bottom surface side of the spacer 80A with respect to the center line L between them.

The spacer 80A is provided with the strength member 83A introduced into the crosshead die of the melt extruder at 15 m / min.
Around the strength member 83A while picking up
It was extruded by supplying a 0 ° C. PBT resin. FIG. 12 is a sectional view of the bottom wall 82 of the completed spacer 80A. As shown in the figure, the height difference of the unevenness generated on the inner surface of the bottom wall 82A was 0.05 mm.
The radius of curvature of the unevenness was 0.4 mm.

Further, an optical cable having substantially the same configuration as the optical cable 60 shown in FIG. 8 was prototyped using the spacer 80A. The core member of this optical cable is a spiral spacer made of HDPE having an outer diameter of 24.5 mm. On the outer periphery of this spiral spacer, a width of 4.6 mm and a depth of 4.6 m are provided.
m slots are formed (SZ inversion angle φ:
300 °, SZ twist pitch P: 360 mm). At the center of the spiral spacer, a tension member in which seven steel wires each having an outer diameter of 2 mm are twisted is incorporated. In each slot, ten 8-core tape core wires each having a thickness of 0.3 mm and a width of 2.1 mm were laminated. A presser-wound tape was wound around the spiral slot without any gap.

Then, around the holding tape, 15
The spacers 80A are assembled in an SZ twist (SZ inversion angle φ: 300 °, SZ twist pitch P: 360)
mm). The spacer 80A accommodates ten 8-core tape cores each. A press-winding tape was wound around the spacer 80A without any gap. A polyethylene jacket was provided on the outer periphery of the holding tape. The length of this optical cable is 200 m and its outer diameter is 45 m
m. The transmission loss at a wavelength of 1.55 μm was measured for the optical fiber housed in each spacer 80A of this optical cable. As a result, 15 spacers 80
For all A, the transmission loss is 0.21-0.25 dB
/ Km, and no increase in transmission loss was observed.

Fifth Embodiment FIG. 13 is a sectional view of a spacer 80B according to a fifth embodiment. In the spacer 80B, as the tensile member 83B, one aromatic polyamide fiber of 1420 denier was used. As shown in FIG. 13, the strength members 83B are arranged close to the bottom surface of the spacer 80B. More specifically, the strength member 83B is formed such that the entirety of the strength member 83B is larger than the center line L between the inner surface of the bottom wall 82B and the outer surface of the bottom wall 82B (the bottom surface of the spacer 80B).
It is arranged so that it may be located on the bottom side of the. Spacer 80B
Dimensions (Bl, Bl, D, bu, bl, d) of FIG.
Is the same as the spacer 80A shown in FIG. As shown in FIG. 13, the spacer 80B includes a tensile strength member 83B.
Are exposed from the bottom surface of the spacer 80B (the outer surface of the bottom wall 82B).

When the completed spacer 80B was cut and its cross section was observed, the height difference of the unevenness generated on the inner surface of the bottom wall 82B was 0.05 mm. The radius of curvature of the irregularities was 0.5 mm or more. Also, this spacer 8
Using OB, a 200 m optical cable was manufactured under the same conditions as in Example 4. The optical fiber housed in each spacer 80B of the optical cable has a wavelength of 1.
The transmission loss at 55 μm was measured. As a result, 15
No increase in transmission loss was observed for any of the book spacers 80B.

Comparative Example 5 FIG. 14 is a sectional view of the spacer 80C of Comparative Example 5. In the spacer 80C shown in the figure, one 1140 denier aromatic polyamide fiber was used as the tensile strength member 83C. As shown in FIG. 14, the central axis of the tensile member 83C is
0.2C from the inner surface of 2C (the bottom surface of the fiber housing portion 84C)
They are arranged so as to be separated by 0 mm. Other conditions (dimensions and the like) are the same as those of the spacer 80A of the fourth embodiment. When the completed spacer 80C was cut and its cross section was observed, as shown in FIG. 15, the height difference of the unevenness generated on the inner surface of the bottom wall 82B was 0.10 mm. The radius of curvature of the unevenness was 0.10 mm. Further, using this spacer 80C, 200 m under the same conditions as in the fourth embodiment.
Was manufactured. The transmission loss at a wavelength of 1.55 μm was measured for the optical fiber accommodated in each spacer 80C of the optical cable. as a result,
The transmission loss of the two optical fibers in contact with the bottom surface of the fiber housing 84C is 0.70, 0.85 dB / k.
m, which proved to be inappropriate for practical use.

Comparative Example 6 FIG. 16 is a sectional view of the spacer 80D of Comparative Example 6. In the spacer 80D shown in the figure, one 1420 denier aromatic polyamide fiber was used as the tensile member 83D. As shown in FIG. 16, the strength member 83D is entirely located closer to the fiber housing portion 84 than the center line L between the inner surface of the bottom wall 82B and the outer surface of the bottom wall 82B (the bottom surface of the spacer 80B). Placed in The other conditions (dimensions, etc.)
Same as B. Cut the completed spacer 80D,
As a result of observing the cross section, as shown in FIG. 17, the height difference of the unevenness generated on the inner surface of the bottom wall 82D was 0.13 mm. The radius of curvature of the unevenness was 0.20 mm. Further, using this spacer 80D, an optical cable of 200 m was produced under the same conditions as in Example 4. The transmission loss at a wavelength of 1.55 μm was measured for the optical fiber housed in each spacer 80D of this optical cable. As a result, some of the optical fibers located near the bottom of the fiber housing 84D have a transmission loss of 0.5%.
Several of them exceeded dB / km, which proved to be impractical.

From the results of this experiment, as in the case of the spacers 80A and 80B, the strength members 83A and 83B were placed with their central axes close to the bottom surface of the spacers.
By arranging with respect to 80B, it is possible to reduce the occurrence of the irregularities caused by the difference between the shrinkage amount of the resin in the portion where the tensile strength members 83A and 83B are present and the shrinkage amount of the resin in other portions. . As a result, the generated irregularities
For example, there is no need to scrape off with a cutting tool or press and smooth a heated flat plate or roller. Therefore, the spacer used for the optical cable can be produced economically without increasing the number of manufacturing steps. Further, when the spacer is formed of a thermoplastic resin, it is not necessary to add an inorganic substance or the like which may impair the smoothness of the fiber housing portion to the thermoplastic resin.

Further, even when the strength members 83B are arranged close to the bottom surface like the spacers 80B, extremely good results in practical use can be obtained. In this case, the tensile strength member 83B is
Since the distance from the bottom surface (the inner surface of the bottom wall) of the fiber housing portion 84B is further increased, the occurrence of unevenness can be suppressed extremely effectively. In the above experiment, an optical cable was used in which each spacer was assembled in an SZ twist around the spiral spacer. On the other hand, it has been confirmed that the same result as described above can be obtained when an optical cable in which spacers such as the optical cable shown in FIG. 1 are assembled around a long cylindrical member is used.

[0087]

According to the present invention, an optical cable having excellent transmission characteristics and excellent core wire take-out properties, and an optical cable spacer applied to this optical cable, in which the spacer is hardly inclined at both the SZ inversion portion and the SZ transition portion. Can be realized.

[Brief description of the drawings]

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

FIG. 2 is a perspective view showing the optical cable of FIG.

FIG. 3 is a sectional view showing a spacer applied to the optical cable shown in FIG. 1;

FIG. 4 is a sectional view of an optical cable spacer.

FIG. 5 is a sectional view of an optical cable spacer.

FIG. 6 is a sectional view of an optical cable spacer.

FIG. 7 is a sectional view of an optical cable spacer.

FIG. 8 is a sectional view showing a second embodiment of the optical cable according to the present invention.

FIG. 9 is a cross-sectional view for explaining a layer center radius and an SZ inversion angle.

FIG. 10 is a sectional view of an optical cable spacer.

FIG. 11 is a sectional view of an optical cable spacer.

FIG. 12 is a partially enlarged sectional view of the optical cable spacer shown in FIG. 11;

FIG. 13 is a sectional view of an optical cable spacer.

FIG. 14 is a sectional view of an optical cable spacer.

FIG. 15 is a partially enlarged sectional view of the optical cable spacer shown in FIG. 14;

FIG. 16 is a sectional view of an optical cable spacer.

17 is a partially enlarged sectional view of the optical cable spacer shown in FIG. 16;

FIG. 18 is a perspective view showing an optical cable spacer assembled around the core member in an SZ twist.

FIG. 19 is a side view showing an optical cable in which spacers are assembled in a SZ twist around a core member.

FIG. 20 is a perspective view showing a spacer curved in the width direction.

FIG. 21 is a perspective view showing a spacer curved in the depth direction.

FIG. 22 is a perspective view showing a spacer curved in the depth direction.

FIG. 23 is a cross-sectional view showing a state in which the spacer has fallen.

FIG. 24 is a cross-sectional view showing a state in which the spacer has fallen.

[Explanation of symbols]

1, 60: optical cable, 2: cylindrical member (core member), 5:
Tape cord (optical fiber), 10, 20, 30, 40,
50, 70, 80A, 80B, 80C, 80D ... spacer, 61 ... spiral slot (core member).

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yoshiyuki Suetsugu 1-chome, Taya-cho, Sakae-ku, Yokohama-shi, Kanagawa Prefecture Sumitomo Electric Industries, Ltd. Yokohama Works (72) Inventor Hideyuki Iwata 3-9-1-2 Nishishinjuku, Shinjuku-ku, Tokyo Nippon Telegraph and Telephone Corporation (72) Inventor Kazunori Watanabe 2-1-1 Yabuta Nishi, Gifu City, Gifu Prefecture Ube Nitto Kasei Co., Ltd.Gifu Research Institute (72) Inventor Sozo Nishikawa 2 Yabuta Nishi, Gifu City, Gifu Prefecture No. 1-1, Ube Nitto Kasei Co., Ltd., Gifu Research Laboratories (72) Inventor Toku Ishii 2-1-1, Yabuta Nishi, Gifu City, Gifu Prefecture Ube Nitto Kasei Co., Ltd. Gifu Research Laboratories (56) References 8-160265 (JP, A) JP-A-7-13054 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) G02B 6/44

Claims (16)

(57) [Claims] 1. A spacer having a fiber accommodation portion for accommodating an optical fiber, and a core member for twisting the spacer, wherein the spacer accommodating the optical fiber is SZ twisted around the core member. In the optical cable having the SZ twisted region gathered in the spacer, the spacer has a property that a bending rigidity in a depth direction of the fiber housing portion is smaller than a bending rigidity in a width direction of the fiber housing portion, and of the strain energy of the spacer in the SZ reverse portion of the SZ stranded region, the distortion energy in the case where the bottom surface of the spacer is in contact with the core member and U _1, the side surface of the spacer is in contact with the core member the strain energy when when the _{U 2, △ U = U 1} -U 2 ≦ 0.2 light and satisfying the (mJ / mm) Ke Bull. 2. The spacer is made of PBT resin and HDPE.
The optical cable according to claim 1, wherein the optical cable is formed of a resin mixed with a resin. 3. The PC / PBT resin and H spacer.
The optical cable according to claim 2, wherein the optical cable is formed of a resin mixture with a DPE resin. 4. The optical cable according to claim 2, wherein the proportion of the HDPE resin in the mixed resin is 20 to 80% by volume. 5. The spacer according to claim 1, wherein the spacer has a bottom wall, and a pair of side walls rising from both ends of the bottom wall, and the fiber receiving portion is formed by the bottom wall and the side walls. The optical cable according to claim 1. 6. The optical cable according to claim 5, wherein the spacer further comprises a tensile member provided at a central portion of the bottom wall in the width direction. 7. The optical cable according to claim 6, wherein the strength member is arranged with a central axis thereof close to the bottom surface. 8. The optical cable according to claim 6, wherein the tensile member is arranged close to the bottom surface. 9. An optical cable spacer having a fiber housing portion for housing an optical fiber and capable of being twisted around a core member of the optical cable, wherein the fiber housing portion has a flexural rigidity in a depth direction. The strain energy in the SZ inversion portion in the SZ region, which has a characteristic smaller than the bending stiffness in the width direction of the fiber housing portion in the SZ twist around the core member, When the strain energy when in contact with the member is U ₁ and the strain energy when the side surface is in contact with the core member is U ₂ , ΔU = U ₁ −U ₂ ≦ 0.2 (mJ / mm). 10. The optical cable spacer according to claim 9, wherein the bottom wall and the side wall are integrally formed of a mixed resin of PBT resin and HDPE resin. 11. The PC / PB, wherein the bottom wall and the side wall are
The optical cable spacer according to claim 9, wherein the spacer is integrally formed of a mixed resin of a T resin and an HDPE resin. 12. The optical cable spacer according to claim 10, wherein the proportion of the HDPE resin in the mixed resin is 20 to 80% by volume. 13. The apparatus according to claim 9, further comprising a bottom wall, and a pair of side walls rising from both ends of the bottom wall, wherein the fiber accommodating portion is formed by the bottom wall and the side walls. 13. The optical cable spacer according to any of 13. 14. The optical cable spacer according to claim 13, further comprising a tensile member provided at a central portion of said bottom wall in said width direction. 15. The spacer for an optical cable according to claim 14, wherein the tensile member is arranged with its central axis close to the bottom surface. 16. The optical cable spacer according to claim 14, wherein the strength member is arranged close to the bottom surface.