JP7269108B2 - fiber optic cable - Google Patents

Description

TECHNICAL FIELD The present invention relates to an optical fiber cable that has high pull-out resistance and excellent branching workability.

Conventionally, an optical fiber cable has been used in which an optical fiber core wire is covered with a jacket. When in use, such optical fiber cores are branched and routed to a plurality of residences or the like.

As such an optical fiber cable, for example, tension members having strength against tension and compression are arranged in parallel on both sides of the optical fiber core wire, and are collectively covered with a cable jacket, and tension members are not arranged. There is an optical fiber cable in which protective walls made of synthetic resin are arranged above and below the optical fiber core wire, which is wider than the arrangement width of the optical fiber core wire, so as to come into contact with the optical fiber core wire (Patent Document 1). .

Japanese Patent Application Laid-Open No. 2008-70601

When branching such an optical fiber cable, it is necessary to divide the jacket into a plurality of pieces and take out the optical fiber core wire inside. At this time, in order to avoid fusion between the optical fiber core wire and the jacket and to easily separate the two, an interposition may be arranged linearly along the optical fiber core wire.

However, the interposition is usually made of a resin such as polypropylene or polyester, and many of such resin materials undergo thermal shrinkage due to crystal rearrangement and relaxation of molecular orientation at high temperatures. For example, the thermal shrinkage of such resin materials reaches several percent. Therefore, in a structure in which the resin material is arranged along the optical fiber core wire in a straight line, the resin shrinks due to heat during manufacture of the optical fiber cable or heat such as solar radiation, which causes meandering of the optical fiber cable.

In addition, when the resin material shrinks while the optical fiber cable is bent, the resin material causes a shortcut and moves to the inside of the bend, and the optical fiber core wire sandwiched under it is pressed, resulting in an increase in loss. there is a risk of

On the other hand, contacting the interposition with the optical fiber core wire suppresses slippage of the optical fiber core wire. Therefore, it is possible to increase the pull-out resistance of the optical fiber core wire in contact with the intervention. However, it is not possible to increase the pull-out resistance of the optical fiber core wire at the portion that is not in contact with the intervention.

On the other hand, there is a method of arranging an interposer by spirally winding it around the optical fiber core wire. However, if the interposition thermally shrinks, the optical fiber core wire may be tightened by the interposition, resulting in an increase in loss. In addition, as described above, when branching an optical fiber cable, the jacket is split and the optical fiber core is taken out from the inside of the optical fiber cable inside. It may not be possible to divide.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an optical fiber cable which has a high pull-out resistance of the internal optical fiber core wire and is excellent in branching workability.

In order to achieve the above object, the present invention provides an optical fiber unit comprising a plurality of optical fiber core wires, interposers disposed so as to be in contact with the optical fiber unit in cross section, and provided on both sides of the optical fiber unit. and an outer cover provided to cover the optical fiber unit, the interposer, and the tension member, and a pair of notches are formed in the outer peripheral portions of the outer cover facing each other, and the notches are connected to each other. By breaking the outer cover, it is possible to separate the tension member into a pair of first separation pieces and a pair of second separation pieces. The interposer is arranged in a longitudinal direction SZ so as not to straddle the pair of first separation pieces , and the interposer is in contact with the jacket .

The intervention may be arranged at two locations so as to sandwich the optical fiber unit.

The displacement angle of the intervening SZ with respect to the longitudinal direction is preferably 30 degrees or more and 300 degrees or less.

It is desirable that the optical fiber unit and the interposer are twisted in different twisting directions in at least a part of the longitudinal direction.

A second invention comprises an optical fiber unit composed of a plurality of optical fiber core wires, a pressure wrap wound around the outer circumference of the optical fiber unit, and an inside of the pressure wrap so as to be in contact with the pressure wrap in cross section. an interposition arranged outside each; tension members provided on both sides of the optical fiber unit; and a jacket provided to cover the optical fiber unit, the interposition and the tension member; A pair of notches are formed in the opposing outer peripheral portions of the cover, and the outer cover is separated from the notches into a pair of first separation pieces containing the tension members and a pair of second separation pieces by breaking the outer cover. In the range of 40 cm in length at an arbitrary position, the interposition arranged outside the pressure wrap is arranged in the longitudinal direction SZ so as not to straddle the pair of first separation pieces,
In at least a part of the longitudinal direction of the optical fiber cable, the intermediates arranged inside and outside the pressure winding are twisted in different twisting directions.

In the first and second inventions, the interposition is preferably yarn.

According to the first and second inventions, since the interposition is arranged in the SZ, even if the interposition is thermally shrunk, the SZ-shaped meandering is only slightly eliminated, and the optical fiber cable or the optical fiber core wire can reduce the impact on In addition, by arranging the interposer in the SZ, it is possible to bring it into contact with more optical fiber core wires, thereby increasing the pull-out resistance of the optical fiber core wires.

In addition, the work of removing the optical fiber core wire from the optical fiber cable is generally performed by cutting the jacket of the optical fiber cable over a length of about 40 cm as a work procedure. On the other hand, splitting the jacket of an optical fiber cable having a pair of tension members produces a pair of first separation pieces including the tension members. In the present invention, the first separation piece including the pair of tension members is not straddled over the 40 cm range in the longitudinal direction of the separation in the separation operation. Therefore, each separation piece can be efficiently divided and the optical fiber core wire inside can be easily taken out.

In addition, if the interposition is provided at two locations so as to sandwich the optical fiber unit, the pull-out resistance of the optical fiber core wire due to the interposition can be increased more efficiently.

In particular, if the displacement angle of the intervention is appropriate, the effect of increasing the pull-out resistance and the effect of improving the branching workability can be obtained more reliably.

In addition, since the optical fiber unit and the intervening material are twisted in different directions in at least a part of the longitudinal direction, even if the intervening material is thermally shrunk, the intervening material does not easily enter the interior of the optical fiber unit, and is difficult to pull out. resistance can be increased.

In particular, according to the second aspect of the present invention, a pressure wrap is wound around the outer circumference of the optical fiber unit, and the intermediates are arranged inside and outside the pressure wrap, respectively, to achieve the above effect. It is easy to control because it can be designed independently for each intervention.

In addition, when a pressure wrap with a smooth surface that does not fuse with the outer covering is used, the frictional force between the pressure wrap, the optical fiber core wire, and the outer covering tends to decrease. On the other hand, since the optical fiber cable has rigidity, for example, when the optical fiber unit is twisted in an SZ shape, the twist tends to return to its original state. At this time, since the pressure winding tends to slip on the optical fiber core wire, if the pressure winding is used, the SZ twist of the optical fiber core wire is eliminated and becomes straight, and when the cable is bent, it will not bend. The core wire on the inside of the meanders and causes an increase in loss.

On the other hand, since the interposition normally has a sufficient frictional force against the outer cover and the optical fiber unit, the interposition can suppress untwisting of the optical fiber unit. At this time, if the inner and outer interventions of the pressure winding are completely twisted in the same direction, there is a risk that the twists of the inner and outer interventions will be untwisted together with the optical fiber unit. If there is, untwisting of the interposition is suppressed at the site. Therefore, the twist of the optical fiber unit in contact with the interposer can be maintained.

In particular, if the intervening material is yarn, the frictional force with surrounding members is sufficiently high, and the pull-out resistance of the optical fiber can be efficiently increased.

According to the present invention, it is possible to provide an optical fiber cable that has a high pull-out resistance of the internal optical fiber core wire and is excellent in branching workability.

Sectional drawing of the optical fiber cable 1. FIG. FIG. 2 is a conceptual diagram showing the arrangement of mediations 5 of the optical fiber cable 1; (a) and (b) are cross-sectional views showing changes in the arrangement of the interposition 5 in the optical fiber cable 1. FIG. (a), (b) is a figure which shows the division|segmentation method of the optical fiber cable 1. FIG. (a) is a cross-sectional view showing the position change range of the intervention 5, and (b) is a conceptual diagram showing the position change of the intervention 5 in (a). (a) is a cross-sectional view showing another position change range of the intervention 5, and (b) is a conceptual diagram showing the position change of the intervention 5 in (a). Sectional drawing of the optical fiber cable 1a. (a), (b) is sectional drawing which shows the change of arrangement|positioning of the intervention 5 in the optical fiber cable 1a. (a) is a cross-sectional view of an optical fiber cable 1b, and (b) is a cross-sectional view of an optical fiber cable 1c. Sectional drawing of the optical fiber cable 1d.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view of an optical fiber cable 1. FIG. The optical fiber cable 1 is composed of a jacket 3, an intermediate 5, an optical fiber unit 17, a tension member 9, a protection wall 13, a support wire 15, and the like.

An optical fiber unit 17 is arranged at a substantially center position of the cross section of the optical fiber cable 1 . The optical fiber unit 17 is composed of a plurality of optical fiber core wires 7 . The optical fiber core wire 7 is, for example, an optical fiber tape core wire in which a plurality of optical fiber strands are intermittently adhered in the longitudinal direction. In the illustrated example, a plurality of optical fibers 7 are stacked in multiple stages. The optical fiber unit 17 may be helically twisted in one direction, or may be twisted in an SZ shape, for example.

In the cross section of the optical fiber cable 1, a pair of protection walls 13 are provided so as to sandwich the entire optical fiber unit 17 from above and below. The protection wall 13 is, for example, a nylon tape or the like, and a material having good peelability from the outer cover 3 is used. The protection wall 13 is formed wider than the optical fiber unit 17 . In addition, the protection wall 13 is in contact with the optical fiber core wires 7 on the uppermost and lowermost stages. The protection wall 13 protects the internal optical fiber core wire 7 from spawning of cicadas after installation. In addition, the protecting wall 13 enhances the ease with which the optical fiber core wire 7 inside can be taken out when the optical fiber core wire 7 is branched, which will be described later.

A pair of tension members 9 are provided on both sides of the optical fiber unit 17 in a direction substantially perpendicular to the facing direction of the protection wall 13 . The tension member 9 bears the tension of the optical fiber cable 1 . For the tension member 9, for example, steel wire, monofilament, fiber-reinforced plastic made of aramid fiber or the like can be used, and galvanized steel wire can be preferably used.

A support wire portion is connected to the cable portion provided with the optical fiber core wire 7 . A support line 15 is provided in the support line portion. The support wire 15 is for supporting the optical fiber cable 1 when laying the optical fiber cable 1 . The support wire 15 can use, for example, a zinc-aluminum plated steel wire.

An intervention 5 is provided on the side of the optical fiber unit 17 and between the protection walls 13 . Interposer 5 is placed in contact with fiber optic unit 17 . The intervening material 5 is formed of yarn (including multifilament (a collection of fibers and fibrous fibers)), tape, or rod-shaped cordel, preferably yarn.

As the material of the yarn, glass fiber, aramid fiber, PP (polypropylene) fiber, PE (polyethylene) fiber, PET (polyester) fiber, nylon fiber, carbon fiber, and a plurality of layers of these can be used. . In addition, it is also possible to use not only individual fibers but also composite aggregated fibers. In addition, the above monofilament fiber can be used as a woven or non-woven fabric in a cord shape, or a split yarn processed from polypropylene, polyethylene, polyester, nylon, etc. It is also possible to use a thin cord-like material, which is processed into a mesh shape by inserting a plurality of slits in the width).

Moreover, the intervention 5 may be formed by twisting a yarn by a predetermined amount. By twisting the yarns, it is possible to suppress the deformation of the yarns and the loosening of the fibers when the optical fiber cable is extruded. Therefore, it is possible to prevent the arrangement disorder of the optical fiber core wires 7 and the accompanying increase in transmission loss. Also, the use of water-absorbing yarn as the interposer 5 can prevent water running in the optical fiber cable.

Moreover, when using a tape as an interposition, PP (polypropylene), PE (polyethylene), PET (polyester), and nylon can be used as the material of the tape.

When a rod-shaped cordel is used as the intervention 5, the material of the cordel includes polyolefin resin, PEN (polyethylene naphthalate), PET (polyethylene terephthalate), thermosetting resin, thermoplastic resin, UV resin, and fiber FRP. A plastic material such as can be used. In addition, the arrangement|positioning of the intervention 5 is mentioned later in detail.

Interposition 5 , optical fiber unit 17 , protection wall 13 , tension member 9 , and support wire 15 are integrated by jacket 3 . That is, the optical fiber unit 17 , protective wall 13 , interposition 5 and tension member 9 are covered with the jacket 3 . The jacket 3 is made of, for example, a polyolefin resin, and preferably LLDPE (linear short-chain branched polyethylene) or the like can be used.

A notch 11 is formed in the outer circumference of the jacket 3 . More specifically, a pair of notches 11 are formed at positions corresponding to the upper and lower protection walls 13 on the opposing outer peripheral portions (upper and lower surfaces in the drawing) of the outer cover 3 . That is, the notches 11 are arranged at a total of four locations. The notch 11 serves as a starting point for splitting the optical fiber cable 1 using, for example, a cable splitting tool.

Next, the arrangement of the intervention 5 will be described in detail. FIG. 2 is a side view of the optical fiber cable 1 and is a conceptual diagram showing the arrangement of the interposition 5. As shown in FIG. As shown in FIG. 2, the interposers 5 are arranged in an SZ shape in the longitudinal direction of the optical fiber cable 1 (twisted alternately in forward and reverse directions).

A cross-sectional view taken along the line AA in FIG. 2 corresponds to FIG. 1 at the twist center position of the SZ arrangement. 3(a) is a cross-sectional view taken along the line BB in FIG. 2, and shows a state in which the intervention 5 is twisted clockwise in the drawing from the state shown in FIG. 3 is a cross-sectional view taken along the line CC of FIG. 2, showing a state in which the intervention 5 is twisted counterclockwise in the drawing from the state of FIG. 1. FIG. In this manner, the intervention 5 changes its position in the longitudinal direction while being in contact with the optical fiber unit 17 on the outer peripheral side of the optical fiber unit 17 .

Although the interposition 5 changes its position in the circumferential direction of the optical fiber unit 17 with respect to the longitudinal direction, the interposition 5 does not enter the inside of the optical fiber unit 17 . That is, the intervention 5 is positioned on the outer circumference of the optical fiber unit 17 at any position in the longitudinal direction.

Further, as described above, it is desirable that the optical fiber unit 17 is twisted, but it is desirable that the optical fiber unit 17 and the interposer 5 are separately twisted. For example, when the optical fiber unit 17 is helically twisted in one direction, the interposer 5 is arranged in an SZ arrangement. It is desirable to By doing so, it is possible to form a portion in which the optical fiber unit 17 and the interposer 5 are twisted in different twisting directions at least partially in the longitudinal direction. For this reason, it is possible to prevent the inclusion 5 from entering the inside of the optical fiber unit 17 and to increase the pull-out resistance of the optical fiber core wire 7 to be described later.

Here, in the case where the intervention 5 is a yarn, and the fineness of the yarn is large and the outer diameter of the yarn is large, by arranging the yarn in an SZ shape, the outer diameter of the cable on the side where the yarn is located is reduced. The diameter swells and the shape of the optical fiber cable 1 becomes uneven in the longitudinal direction. Therefore, in order to make the shape of the optical fiber cable 1 uniform, it is desirable to set the fineness of the yarn to 2000 denier or less.

Next, branching work using the optical fiber cable 1 will be described. First, as shown in FIG. 4A, the support wire portion and the cable portion are separated. A cutting edge 23 of a split tool is arranged in the notch 11 .

From this state, the cutting blade 23 is inserted up to the protective wall 13 to cut the notch 11 of the jacket 3 in the longitudinal direction. By doing so, as shown in FIG. 4(b), the upper and lower jackets 3 of the protection wall 13 are divided by the breaking portion 21 with respect to the optical fiber unit 17 (in the direction of the arrow F in the figure), Also, the jacket 3 including the tension member 9 is divided (in the direction of arrow E in the figure).

Here, the cut jacket 3 including the tension member 9 is referred to as a first separation piece 19a, and the jacket 3 separated by the protection wall 13 is referred to as a second separation piece 19b. That is, by breaking the outer cover 3 from the notch 11 at the breaking portion 21, a pair of first separation pieces 19a including the tension member 9 and a pair of first separation pieces 19a separated by the protective wall 13 (not including the tension member 9) It is possible to separate into four separate pieces of the second separation piece 19b.

Since the jacket 3 and some of the optical fiber cores 7 are in contact with each other, there is a possibility that the jacket 3 and the optical fiber cores 7 are fused. With proper care, this effect can be reduced.

In the state shown in FIG. 4(b), the intervention 5 is separated integrally with the first separation piece 19a on the left side of the drawing. However, as described above, the placement of the intervention 5 varies in the longitudinal direction of the optical fiber cable 1 . Therefore, as shown in FIG. 4(b), the intervention 5 is not integrated with the one first separation piece 19a over the entire length.

FIG. 5(a) is a sectional view showing the displacement range of the intervention 5. FIG. In this embodiment, the central position of the SZ arrangement is the position shown in FIG. 5(a) (on line O in the figure). In addition, let the position of the intervention 5 be the center position with respect to the circumferential direction of the intervention 5. As shown in FIG. That is, in this embodiment, at the center of the SZ arrangement, the intervention 5 passes through the center of the pair of tension members 9 and is arranged at a position facing one tension member 9 (on the left side in the drawing).

The intervention 5 changes its position alternately clockwise (+ direction in the drawing) and counterclockwise (- direction in the drawing) from the central position O of the SZ arrangement. Here, H and I in the drawing are the ranges that become the first separation piece 19a including the tension member 9 when the outer cover 3 is broken at the breaking portion 21. As shown in FIG. That is, depending on the position in the circumferential direction, the intervention 5 may be located in a range where it is integrated with the first separation piece 19a and a range where it is not integrated with the first separation piece 19a.

FIG. 5(b) is a conceptual diagram showing the position of the intervention 5 in the longitudinal direction. It shows the displacement angle of the direction. That is, 180° is the position facing the tension member 9 on the right side in FIG. 5(a). Also, Q in the figure indicates the position of the intervention 5, and P in the figure indicates the pitch of the SZ arrangement.

Here, H and I in FIG. 5(b) correspond to the angular range of H and I in FIG. 5(a). That is, in FIG. 5B, in the longitudinal range where the intervention 5 is within the range H, the intervention 5 is integrated with and separated from the first separation piece 19a on the left side in FIG. is within the I range, the intervention 5 is separated integrally with the first separating piece 19a on the right side of FIG. 4(b). In addition, at a portion where the interposition is not in the range of H and I (range J in the figure), the interposition 5 is separated separately from each separation piece.

As described above, the normal operation of removing the optical fiber core wire 7 from the optical fiber cable 1 is generally performed by cutting the jacket 3 of the optical fiber cable 1 over a length of about 40 cm as a work procedure. . Therefore, many of the closures that accommodate the connection between the optical fibers can accommodate an extra length of about 40 cm.

In the present embodiment, the length J, which is the length range in which the intervention 5 is not included in the first separation piece 19a, is set to 40 cm or more, which is the length to be cut during the take-out operation. By doing so, when the optical fiber cable 1 is broken by 40 cm at any position in the longitudinal direction, the intervention 5 is placed across the two first separation pieces 19a (that is, H and I in the figure). never be

As described above, the intervention 5 and the first separation piece 19a are integrated at the position corresponding to the first separation piece 19a. For this reason, when the optical fiber cable 1 is separated, if the interposition 5 straddles both of the pair of first separation pieces 19a, the interposition 5 connects the pair of first separation pieces 19a to each other. put away. Therefore, each separation piece cannot be completely separated. As a result, there is a risk of hindering the work of taking out the optical fiber core wire 7 inside.

On the other hand, if the intervention 5 is integrated with only one of the first separation pieces 19a, all the separation pieces can be easily separated from each other. In addition, between H and I in the figure, the intervention 5 is separated without being integrated with each separation piece, so there is no effect on the work of taking out the optical fiber core wire 7 inside.

In this way, by setting the pitch of the SZ arrangement of the interposition 5 so that the interposition 5 does not straddle the pair of first separation pieces 19a in the range of 40 cm in length at any position of the optical fiber cable 1, Workability for taking out the optical fiber core wire inside is improved.

In the example shown in FIG. 5, the central position O of the SZ arrangement of the intervention 5 is the position facing one of the tension members, but the present invention is not limited to this. For example, FIG. 6(a) is a cross section showing a case where the central position O' of the SZ arrangement of the intervention 5 is perpendicular to FIG. FIG. 6B is a conceptual diagram showing the longitudinal position of the intervention 5 in this case.

As in FIG. 5(a), the intervention 5 alternates clockwise (+ direction in FIG. 6(a)) and counterclockwise (− direction in FIG. 6(a)) from the central position O′ of the SZ arrangement. position changes to Also in this case, H and I in the drawing indicate the range where the first separation piece 19a and the interposition 5 are integrated. In addition, at a portion where the interposition is not in the range of H and I (range M in the figure), the interposition 5 is separated separately from each separation piece.

In the present embodiment, the length M, which is the length range in which the intervention 5 is not included in the first separation piece 19a, is set to 40 cm or more, which is the length to be cut during the take-out operation. By doing so, when the optical fiber cable 1 is broken by 40 cm at any position in the longitudinal direction, the intervention 5 is placed across the two first separation pieces 19a (that is, H and I in the figure). never be In this way, depending on the central position of the SZ arrangement of the intervention 5, the SZ is arranged such that the length (J, M) of the intervention 5 that is not included in either of the pair of first separation pieces 19a is 40 cm or more. By setting the arrangement pitch P and the like, the work of extracting the optical fiber core wire 7 inside is facilitated.

In this way, in order to prevent the intervention 5 from straddling both first separation pieces 19a in the 40 cm length range of the optical fiber cable 1, the pitch P of the SZ arrangement of the intervention 5 is increased. go. If the pitch P of the SZ arrangement is increased, it is possible to suppress the inclusion 5 from being integrated with both the first separation pieces 19a within the range of 40 cm. On the other hand, if the pitch P of the SZ arrangement of the interventions 5 is made too large, the intervenings 5 are arranged in a straight line, so the effect of the SZ arrangement is reduced. Therefore, it is desirable that the pitch P of the SZ arrangement of the interventions 5 is 300 cm or less.

In addition, the displacement angle of the SZ arrangement with respect to the longitudinal direction (the sum of the positive direction angle and the reverse direction angle with respect to the center of the SZ arrangement, and the angle difference from the minimum angle to the maximum angle of Q in FIG. 5(b)) is 30 It is desirable that the angle is not less than 300 degrees and not more than 300 degrees. If the displacement angle is too small, the effect of the SZ arrangement is small. Also, if the displacement angle is too large, the pitch P must be increased in order to make the length (J, M) that is not included in either of the pair of first separation pieces 19a greater than or equal to 40 cm. The effect of placement is reduced.

It should be noted that, for example, in the case where the intervention 5 is arranged as shown in FIG. When the angle is less than a predetermined value), regardless of the pitch P, the intervention 5 is not integrated with the first separation piece 19a on the right side in the drawing. Similarly, in the case of the arrangement of FIG. 6(a), when the intervention 5 performs the SZ arrangement in a range that does not fall within the ranges H and I from the center O' of the SZ arrangement, regardless of the pitch P, Interposition 5 is not integrated with first separation piece 19a.

In practice, the intervention 5 has a predetermined length in the circumferential direction. Therefore, even if the central position of the intervention 5 is not within the ranges H and I, part of the intervention 5 may be integrated with the first separation piece 19a. Therefore, when setting the pitch of the SZ arrangement of the interventions 5, the size of the interventions 5 (that is, the clockwise tip position and the counterclockwise tip position of the interventions 5) is also taken into consideration.

As described above, according to the present embodiment, the SZ arrangement of the interposition 5 allows the SZ arrangement of the interposition 5 to expand somewhat when the interposition 5 is thermally contracted. can be suppressed. Therefore, an increase in transmission loss can be suppressed.

Further, since the interposition 5 is arranged in the SZ, the interposition 5 and the optical fiber unit 17 can be efficiently brought into contact with each other. For example, the length of contact between the interposition 5 and the optical fiber unit 17 can be made longer than when the interposition 5 is arranged in a straight line. Therefore, the pull-out resistance of the optical fiber core wire 7 can be increased.

At this time, since the interposition 5 is not twisted integrally with the optical fiber unit 17, when the optical fiber core wire 7 is pulled out, the interposition 5 and the optical fiber unit 17 are untwisted, and the optical fiber core wire 7 is wrapped. There is no withdrawal from 3. In addition, since the interposition 5 is not twisted together with the optical fiber unit 17, when the interposition 5 is thermally shrunk, the interposition 5 enters between the optical fiber core wires 7 and presses the optical fiber core wires 7. Therefore, it is possible to suppress an increase in transmission loss. In particular, since the intervention 5 is not spirally wound in one direction, it is possible to suppress an increase in transmission loss due to tightening of the optical fiber 7 inside due to thermal contraction or the like.

Further, since the optical fiber core wire 7 has a high rigidity, if the optical fiber unit 17 is twisted, a force is generated in the optical fiber unit 17 to untwist it. At this time, since there is a part in which the twisting direction of the interposition 5 and the optical fiber unit 17 is different, when the twist of the optical fiber unit 17 tries to return, the twist of the interposition 5 becomes tighter. This serves as a resistance to untwisting of the fiber unit 17 . Therefore, the twist of the optical fiber unit 17 can be maintained.

Further, when the jacket 3 of the optical fiber cable 1 is split and the optical fiber core wire 7 inside is taken out, the interposition 5 is placed between the pair of first separation pieces 19a including the tension member 9 in the range of the take-out length. They are not placed across each other. Therefore, each separation piece can be easily separated and the optical fiber core wire 7 inside can be taken out.

Next, a second embodiment will be described. FIG. 7 is a cross-sectional view showing an optical fiber cable 1a according to the second embodiment. In the following description, the same reference numerals as those in FIGS. 1 to 6 are given to the structures having the same functions as in the first embodiment, and duplicate descriptions are omitted.

The optical fiber cable 1a has substantially the same configuration as the optical fiber cable 1, but differs in that the interposer 5 is arranged at two locations so as to sandwich the optical fiber unit 17 therebetween. Each interposer 5 is respectively SZ arranged with respect to the longitudinal direction.

FIGS. 8(a) and 8(b) are diagrams showing changes in arrangement of the interventions 5, corresponding to FIGS. 3(a) and 3(b). The interposers 5 arranged on both sides of the optical fiber unit 17 are SZ arranged in the same direction (clockwise or counterclockwise) with the same pitch. That is, the interventions 5 do not cross each other.

The center position of the SZ arrangement of the intervention 5 may not be the position facing the tension member 9 as shown in FIG. facing direction of the protective wall 13). In any case, the intermediates 5 are arranged 180° opposite to each other in the circumferential direction of the optical fiber unit 17 .

Moreover, when two interventions 5 are arranged so as to sandwich the optical fiber unit 17, the displacement angle of the SZ arrangement of each intervention 5 may be reduced. For example, in FIG. 5(b), one interposition 5 is in the range of ±90° or less with respect to the SZ arrangement center of 0°, and the other interposition 5 is in the range of ±90° or less with respect to the SZ arrangement center of 180°. It may be a range. By doing so, each intervention 5 is not integrated with the other first separation piece 19a, so the pitch of the SZ arrangement can be reduced.

As described above, according to the second embodiment, the same effects as those of the first embodiment can be obtained. In addition, since two interventions 5 are arranged, the contact area between the interventions 5 and the optical fiber unit 17 can be increased, and the pull-out resistance of the optical fiber core wire 7 can be increased more efficiently.

Next, a third embodiment will be described. FIG. 9(a) is a cross-sectional view showing an optical fiber cable 1b according to the third embodiment. The optical fiber cable 1b has substantially the same configuration as the optical fiber cable 1, but differs in that a pressure wrap 25 is provided. The optical fiber unit 17 of the optical fiber cable 1b is formed by winding a plurality of optical fiber core wires 7 with a pressure winding 25. As shown in FIG.

As the presser wrap 25, a plastic tape member such as PET or a non-woven fabric can be used. When the pressure winding 25 is arranged, the protective wall 13 must be arranged when using a cable that does not need to prevent the spawning of cicadas or a high-strength jacket 3 that does not allow the ovipositor of cicadas to pass through. good too. In this case, a notch is made along the notch 11 at the end of the optical fiber cable 1b, and the wrap 25 is taken out by tearing the jacket 3 in the longitudinal direction. be able to.

In this case, the intervention 5 is arranged so as to be in contact with the outer periphery of the pressure winding 25 . That is, the intervention 5 contacts the outer peripheral portion of the optical fiber unit 17 including the pressure wrap 25 . Since the optical fiber unit 17 is held down by the intervention 5 in this way, the pull-out resistance of the optical fiber core wire 7 inside can be increased.

In order to increase the pull-out resistance of the optical fiber core wire 7 more efficiently, the intervention 5 may be arranged inside the pressure winding 25 as in the case of the optical fiber cable 1c shown in FIG. 9(b). In this case, the interposition 5 is SZ arranged around the optical fiber core wire 7 inside the pressure winding 25 .

Here, considering the ease of withdrawing the optical fiber core wire 7 inside, it is desirable that the pressure wrap 25 is not fused to the jacket 3 . In particular, if the pressing wrap 25 is made of a material that has a smooth surface and is slippery, the frictional force with the optical fiber core wire 7 inside becomes small. cannot be increased.

On the other hand, as mentioned above, the optical fiber unit 17 may also be SZ twisted. In this case, due to the rigidity of the optical fiber core wire 7 , a force is generated to untwist the optical fiber unit 17 . However, as described above, the pressure wrap 25 has a weak effect of gripping the optical fiber core 7 and the jacket 3 and is slippery. When the optical fiber cable is bent, it returns to its original shape and becomes straight, and when the optical fiber cable is bent, there is a risk that the optical fiber core wire inside the bend will meander and increase the loss.

On the other hand, as in the optical fiber cable 1d shown in FIG. Interposers 5 and 5a contact the inner and outer surfaces of the pressure wrap 25, respectively. It should be noted that the interpositions 5 and 5a have greater frictional resistance with the surrounding jacket 3 and the optical fiber core wire 7 than the restrainer wrap 25 does.

In this case, the interposer 5 inside is easy to manufacture by performing SZ twisting with the same pitch and phase as the optical fiber unit 17 . On the other hand, the outer flutes 5a are SZ-twisted with a different pitch or phase than the flutes 5. That is, in at least a part of the longitudinal direction, the interpositions 5 and 5a inside and outside the pressure winding 25 are twisted in different twisting directions. For example, the outer interventions 5a are arranged at the same pitch with respect to the inner interventions 5 with a phase shift of 1/2 period.

By doing so, for example, when the optical fiber unit 17 is twisted in the S direction, the outer intervention 5a is twisted in the Z direction. Therefore, when the twist of the optical fiber unit 17 and the interposition 5 tries to be untwisted, the twist of the interposition 5a on the outside becomes tighter. can be suppressed.

As described above, according to the third embodiment, the same effects as those of the first embodiment can be obtained. In addition, by using the pressure wrap 25, it is possible to suppress fusion between the optical fiber core wire 7 and the jacket 3. FIG.

Several types of optical fiber cables were produced and evaluated for the increase in transmission loss during temperature cycles, ease of extraction, meandering of the cable, and pull-out force of the optical fiber core wire.

Six 4-core intermittent tape core wires using optical fiber core wires of Φ0.25 mm were twisted in a spiral to form an optical fiber unit of 24 cores. Also, 1500d (denier) polypropylene split yarn (string-like) was used as an intervening material. Before manufacturing the optical fiber cable, this interposition was heated at 130° C. for 30 minutes to measure the thermal shrinkage, which was 3%.

A nylon tape having a thickness of 0.2 mm and a width of 3.2 mm was used as a protective barrier. A galvanized steel wire with a diameter of Φ0.5 mm was used as the tension member. A Φ2.6 mm zinc aluminized steel wire was used as the support wire. LLDPE was used for the jacket.

A PET film having a thickness of 40 μm was used as the pressure winding. One intervention was placed inside the pressure wrap. Table 1 shows the results.

In the table, "the straddling of the first separation piece" is defined as "present" when the interposition is arranged to straddle the pair of first separation pieces including the tension member at an arbitrary length of 40 cm. If the inclusion 5 was integrated with only one of the first separation pieces or was not integrated with any of the first separation pieces at a length of 40 cm, it was evaluated as "none".

In addition, the "SZ pitch" in the table is the length of the optical fiber cable (P in Fig. 5 (b)) until the interposer rotates in the forward direction, reverses and rotates in the reverse direction, and returns to its original position. is.

Further, the "displacement angle" in the table indicates the sum of the rotation angles in the forward direction and the reverse direction, for example, the total angle difference from the minimum angle to the maximum angle in FIG. 5(b).

For the temperature cycle, the cable was wound around a drum with a trunk diameter of 500 mm, and a temperature cycle test was performed by a method according to IEC60794-1-22. One temperature cycle was -30° to 70°, and 10 cycles were repeated. The retention time was 6 hours at each temperature. If the maximum value of loss increase is 0.08 dB/km or less, it is acceptable and the result is good (○). If it was large, it was set as failure (x).

For the evaluation of "removability", a 400 mm cut was made in the intermediate portion of the cable with a length of 1 m using a cable dismantling tool, the jacket was divided, and the optical fiber was taken out from the inside. At this time, the case where the optical fiber core wire could be easily taken out was evaluated as a pass (○), and the case where the interposition was difficult to remove and the optical fiber core wire was difficult to remove was evaluated as a failure (x).

In addition, "cable meandering" was determined by extending the optical fiber cable after manufacturing and after the above temperature cycle test in a straight line for 10 m on a horizontal floor, and observing whether the cable meandered or not. A case in which no meandering of the cable was observed was evaluated as pass (○), and a case in which meandering was observed was disqualified (x).

As for the "pull-out force", the optical fiber core wire was taken out by removing the jacket and other members of 50 cm at both ends of the 11 m cable. Next, the optical fiber unit at one end was pulled, and the tension when the optical fiber unit at the opposite end started to move was measured as the pull-out force of the optical fiber core wire. A pull-out force of 25 N/10m or more was regarded as a pass and a good result (○), a pull-out force of 20 N/10 m or more and less than 25 N/10 m was regarded as a pass (Δ), and a pull-out force of less than 20 N/10 m was regarded as a fail (x).

From the results, all of Examples 1 to 11, in which the first separation piece did not span over, were evaluated as ◯ in terms of removal performance. In addition, since the interposition is in the SZ arrangement, the increase in loss, meandering, and pull-out force are Δ or more. On the other hand, in Comparative Examples 1 to 3, in which the first separation piece straddled, the take-out performance was poor. In addition, in Comparative Example 4 with a small displacement angle, meandering of the cable occurred after the temperature cycle test. In addition, Comparative Example 5, in which the intervening material was arranged with an S twist, had an increase in loss during the temperature cycle and was evaluated as x. Comparative Example 6, in which the interposition was not in the SZ arrangement, was x in terms of increased loss, meandering, and pull-out force.

Although the embodiments of the present invention have been described above with reference to the accompanying drawings, the technical scope of the present invention is not affected by the above-described embodiments. It is obvious that a person skilled in the art can conceive of various modifications or modifications within the scope of the technical idea described in the claims, and these are naturally within the technical scope of the present invention. be understood to belong to

For example, it goes without saying that each embodiment can be combined with each other. Also, the central position of the SZ arrangement of the intervention 5 does not have to be a constant position in the longitudinal direction. For example, the clockwise displacement angle and the counterclockwise displacement angle of the intervention 5 may be different.

1, 1a, 1b, 1c --- Optical fiber cable 3 --- Jacket 5, 5a --- Intermediate 7 --- Optical fiber cable 9 --- Tension member 11 --- Notch 13 --- Protection Wall 15 Support wire 17 Optical fiber unit 19a First separation piece 19b Second separation piece 21 Broken portion 23 Cutting edge 25 Presser winding

Claims (6)

an optical fiber unit comprising a plurality of optical fiber core wires;
an interposer positioned in cross section to contact the optical fiber unit;
tension members provided on both sides of the optical fiber unit;
a jacket provided to cover the optical fiber unit, the interposition and the tension member;
and
a pair of notches are formed in opposing outer peripheries of the outer cover, respectively;
By breaking the outer cover from the notch, it is possible to separate the tension member into a pair of first separation pieces and a pair of second separation pieces,
In the range of 40 cm in length at any position, the intervention is arranged in the longitudinal direction SZ so as not to straddle the pair of first separation pieces ,
A fiber optic cable , wherein said interposer is in contact with said jacket . 2. The optical fiber cable according to claim 1, wherein said intermediates are arranged at two locations so as to sandwich said optical fiber unit. 3. The optical fiber cable according to claim 1, wherein the displacement angle of the SZ arrangement of the intervention with respect to the longitudinal direction is 30 degrees or more and 300 degrees or less. 4. The optical fiber cable according to any one of claims 1 to 3, wherein the optical fiber unit and the intermediate are twisted in different twisting directions in at least a part of the longitudinal direction. an optical fiber unit comprising a plurality of optical fiber core wires;
a pressure winding wound around the outer periphery of the optical fiber unit;
Interposers disposed inside and outside the head wrap so as to be in contact with the head wrap in cross section;
tension members provided on both sides of the optical fiber unit;
a jacket provided to cover the optical fiber unit, the interposition and the tension member;
and
a pair of notches are formed in opposing outer peripheries of the outer cover, respectively;
By breaking the outer cover from the notch, it is possible to separate the tension member into a pair of first separation pieces and a pair of second separation pieces,
In the range of 40 cm in length at an arbitrary position, the intervention placed outside the pressure wrap is arranged in the longitudinal direction SZ so as not to straddle the pair of first separation pieces,
An optical fiber cable, wherein the intermediates arranged inside and outside the pressure winding are twisted in different twisting directions in at least a part of the longitudinal direction. 6. A fiber optic cable as claimed in any preceding claim, wherein the intervening material is a yarn.

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