JP2005055704A - Optical fiber cable and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To extremely improve anchoring force to a coated optical fiber, without increasing transmission loss. <P>SOLUTION: The optical fiber cable 1 consists of a long optical element part 13 in which the coated optical fiber 3 consisting of a single or a plurality of fibers or a coated fiber tape and tension resistant bodies 9 for the optical element disposed on both the sides of the coated optical fiber are covered with a cable sheath 11, along the extending direction of the coated optical fiber 3. With respect to the second direction perpendicular to the first direction connecting each of the tension resistant bodies 9 for the optical element, each side of the surface of the cable sheath 11 of the coated optical fiber 3 is provided with at least one notch part 15. The anchoring force of the coated optical fiber 3 is in the range of from 30 N/300 mm to 310 N/300 mm. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a multi-fiber pulling optical fiber cable and a manufacturing method thereof.

  Referring to FIG. 9, when an optical fiber cable 101 sheathed with an optical fiber core consisting of a plurality of strands or tape cores is conventionally laid, many optical fibers of a termination cable 101A (Termination Cable) Are connected by an optical connector (not shown) or the like in a distribution board (MDF: Main Distribution Frame, abbreviated as “MDF”) as an optical fiber concentrator provided in a termination cabinet 105 in the telephone office 103. ing.

  Since the optical fiber cable 101 has a limited length, several optical fiber cables 101 are connected and extended. For example, the termination cable 101A is connected to an underground cable 101B (Underground Cable) by an underground connection closure 109 in the manhole 107, and between each manhole 107 is extended by an underground cable 101B. Further, when the electric cable 111B is wired from the underground cable 101B, the electric cable 111 is wired by the riser cable 101C (Riser Cable) connected by the underground connection closure 109 in the manhole 107, and the overhead cable 101D (Aerial) is connected between the electric poles 111. Cable). Note that the termination cable 101A, the underground cable 101B, the riser cable 101C, and the aerial cable 101D are all optical fiber cables 101.

  Each optical fiber of the aerial cable 101D is pulled down to the building or each subscriber's home 115 by an optical fiber drop cable 101E covering the optical fiber with an aerial connection closure 113, and is installed in an indoor OE converter or termination. Connected to the box.

  About 1 or 2 cores are usually used as optical fiber cables 101 (drop cables) for premises and aerials, but about 4 to 10 cores for small-scale condominiums and buildings with the expansion of FTTH (Fiber to the home). Demand for multi-centering is expected.

  Further, from the viewpoint of the post-branch workability, it is considered effective to use a single strand (or a tape optical fiber core having about two cores) as the optical fiber core to be housed.

  When trying to design a multi-fiber dropping optical fiber cable 101 with a single optical fiber core wire, a loose tube cable, a slot cable, etc. can be considered. A cable having a small diameter and a simple drop indoor cable 117 as shown in FIG. 10 is effective. That is, in FIG. 10, a drop indoor cable 117 as an optical fiber cable 101 includes a single optical fiber core 119 and an optical element strength member 121 arranged in parallel on both sides in the vicinity of the cable sheath 123. The notch portions 125 are formed on the surface of the cable sheath 123 on both sides (up and down in FIG. 10) of the optical fiber core wire 119 in a direction orthogonal to the direction in which the optical element strength members 121 are connected. It is formed (see, for example, Patent Document 1).

Referring to FIG. 11, an optical fiber drop cable 127 as the optical fiber cable 101 includes a cable sheath 123 of the drop / indoor cable 117, and a support wire 129 made of the same resin sheath material 131 as the cable sheath 123. The covered long cable support line part 133 is integrated through a neck part 135 in parallel with each other (see, for example, Patent Document 2).
JP 2000-171673 A JP 2001-83385 A

  However, as shown in FIG. 12, when an optical fiber drop cable 127 is intended to accommodate a multi-core optical fiber 119 instead of a single-core optical fiber 119, a plurality of optical fiber cores are used. When the 119 is bundled and sheathed by solid extrusion, the cable sheath 123 has a compressive force in the radial direction toward the center of the cable sheath 123 (center of the optical element portion) due to the positional relationship between the die and the nipple of the extruder. In order to work, after the extrusion, the optical fiber core wire 119 and the cable sheath 123 are in close contact with each other, so that the pulling force is also increased. In this case, the lateral pressure applied to the optical fiber core wire 119 increases, resulting in an increase in transmission loss. In addition, since the sheath material 123 bites into the optical fiber core wire 119, a problem arises in the lead-out property.

  On the other hand, as shown in FIG. 13, in this optical fiber drop cable 137, a multi-core optical fiber 119 is inserted into a pipe connected to a through-hole (nipple hole) of a nipple in an extrusion head and is removed from the pipe. When extruded, the multi-core optical fiber 119 becomes a scar in the hollow portion 139, so that the optical fiber 119 may move in the cable 127 after construction (in the connection closure 113 or the termination cabinet 105). Therefore, the optical fiber core wire 119 may be locally bent and transmission loss may increase).

  That is, in the pipe extrusion, even if the cable sheath 123 is formed in a pipe shape having the hollow portion 139 and is compressed in the radial direction, a force for tightening the optical fiber core wire 119 does not occur. Therefore, the adhesion force between the cable sheath 123 and the optical fiber core wire 119 is zero, and the retention force of the optical fiber core wire 119 in the longitudinal direction is also zero. In this case, since there is no lateral pressure on the optical fiber core 119, there is no deterioration in transmission loss at the initial stage of the installation of the optical fiber cable 101. Become. In FIG. 9A, since the optical fiber core wire 119 accumulates downward due to gravity and vibration, the optical fiber is locally bent and compressed, and transmission loss is deteriorated.

  The present invention has been made to solve the above-described problems.

An optical fiber cable of the present invention includes an optical fiber core wire,
Strength members disposed on both sides of the optical fiber core along the extending direction of the optical fiber core;
A cable sheath for covering the optical fiber core and the tensile body, and cables on both sides of the optical fiber core in a second direction perpendicular to the first direction connecting the tensile bodies in a plane perpendicular to the extending direction. Cable sheaths each having at least one notch formed on the surface of the sheath;
Having a long optical element portion comprising
The holding force of the optical fiber core wire is in the range of 30 N / 300 mm to 310 N / 300 mm.

  Therefore, an optical fiber having a small diameter and excellent loss characteristics and workability is provided. Moreover, the optical fiber cable formed so that the retention force of the optical fiber core wire is in the range of 30 N / 300 mm to 310 N / 300 mm when the sheath is extruded is not too strong and is not too weak. Therefore, for example, it is prevented that the transmission loss is deteriorated because the cable sheath bites into the optical fiber core and is compressed when the retention force is too strong. Further, the tendency of the optical fiber to move downward according to gravity when the retention force is too weak, macro bending occurs at a position where the hanging position of the optical fiber cable is low, and bending loss occurs is prevented. That is, the core wire movement during overhead wiring is suppressed.

  The optical fiber cable according to the present invention is a long cable support line portion in which the support line is covered with a sheath in the optical fiber cable, and the cable support line portion is arranged in parallel with the optical element portion and integrated. It is preferable to have.

  In the optical fiber cable according to the present invention, it is preferable that the optical fiber core has one or a plurality of strands or tape cores. Therefore, it is widely applied to the optical fiber core wire of a single strand or a some strand or a tape core wire.

  In the optical fiber cable according to the present invention, in the optical fiber cable, a straight line connecting points closest to the optical fiber core wire of the notches in the plane orthogonal to the extending direction is defined by the optical fiber core wire. It is preferable to intersect with the boundary line of the shape of the hole formed in the sheath. Accordingly, when the cable sheath is torn from the notch and the optical fiber core wire is extracted, the extraction is easily performed.

  In the optical fiber cable of the present invention, it is preferable that the straight line is parallel to the second direction in the plane. Accordingly, when the cable sheath is torn from the notch and the optical fiber core wire is extracted, the extraction is easily performed.

The method of manufacturing an optical fiber cable according to the present invention includes: an optical fiber core wire; and tensile strength members disposed on both sides of the optical fiber core wire along a direction in which the optical fiber core wire is stretched, respectively. Supplying, and
Extruding a thermoplastic resin into the extrusion head;
A step of forming an optical element portion in which the optical fiber core and the tensile body are covered with a cable sheath, wherein the clearance between the die portion and the nipple portion constituting the extrusion head is determined by the retention force of the optical fiber core wire. A step of adjusting to be in a range of 30 N / 300 mm to 310 N / 300 mm, and on both sides of the optical fiber core wire in a second direction orthogonal to the first direction connecting the strength members in a plane perpendicular to the stretching direction. Forming an optical element portion including a step of forming a notch portion on the surface of the cable sheath;
It is what has.

  Therefore, the optical fiber cable obtained by this manufacturing method is provided with an optical fiber having a small diameter and excellent loss characteristics and workability. Moreover, the optical fiber cable formed so that the retention force of the optical fiber core wire is in the range of 30 N / 300 mm to 310 N / 300 mm when the sheath is extruded is not too strong and is not too weak. Therefore, for example, it is prevented that the transmission loss is deteriorated because the cable sheath bites into the optical fiber core and is compressed when the retention force is too strong. Further, the tendency of the optical fiber to move downward according to gravity when the retention force is too weak, macro bending occurs at a position where the hanging position of the optical fiber cable is low, and bending loss occurs is prevented. That is, the core wire movement during overhead wiring is suppressed.

The method of manufacturing an optical fiber cable according to the present invention includes an optical fiber core, a tensile body disposed on both sides of the optical fiber core along a direction in which the optical fiber core is stretched, and a support wire that respectively run and extrude. Supplying the head;
Extruding a thermoplastic resin into the extrusion head;
An optical element portion in which the optical fiber core wire and the tensile body are covered with a cable sheath, and a cable support wire portion in which the support wire is covered with a sheath are arranged in parallel and integrally formed, Adjusting the clearance between the die part and the nipple part constituting the extrusion head so that the holding force of the optical fiber core is in a range of 30 N / 300 mm to 310 N / 300 mm; and the extending direction of the optical fiber core Forming a notch portion on the surface of the cable sheath on both sides of the optical fiber core wire in the second direction orthogonal to the first direction in the plane perpendicular to the first direction,
It is what has.

  The method for manufacturing an optical fiber cable according to the present invention can provide the same operation as the above-described method for manufacturing an optical fiber cable.

  An optical fiber cable manufacturing method according to the present invention is the optical fiber cable manufacturing method, wherein a plurality of optical fiber cores are arranged and passed through a nipple hole of a cylindrical body provided in the nipple portion and the nipple hole. Is preferably a cross-sectional shape adapted to the arrangement of a plurality of optical fiber cores. Accordingly, the retention force of the optical fiber core wire can be easily adjusted.

  The optical fiber cable manufacturing method of the present invention is the optical fiber cable manufacturing method, wherein the step of supplying the optical fiber core wire / tensile body to the extrusion head and the step of supplying the thermoplastic resin to the extrusion head are simultaneously performed. Preferably, it is done. Therefore, the optical fiber cable is rapidly manufactured in a series of continuous processes.

  As can be understood from the description of the embodiments of the invention as described above, according to the present invention, it is possible to provide an optical fiber cable having a small diameter and excellent loss characteristics and workability. In addition, the optical fiber core wire can be easily led out by tearing the cable from the notch portion.

  In addition, since the sheath extrusion method controls and pushes the adhesion force or the retention force with respect to the optical fiber core wire, an appropriate adhesion force or retention force can be obtained. As a result, the retention force can be greatly improved without impairing the transmission characteristics, and the core wire movement during overhead wiring can be suppressed.

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

  Referring to FIG. 1, an optical fiber cable 1 according to a first embodiment of the present invention has an optical fiber core wire 3 composed of a plurality of strands. In the vicinity of both sides of the optical fiber core 3 (left and right in FIG. 1), the optical element tensile body 5 is arranged in parallel along the extending direction of the optical fiber core 3.

  The optical fiber core wire 3 and the optical element strength member 5 are covered with a cable sheath 7 made of a thermoplastic resin to form a long optical element portion 9. In this case, the optical fiber core wire 3 and the cable sheath 7 are configured so that an appropriately controlled adhesion force acts. That is, an appropriate adhesion force is a range in which the holding force of the optical fiber core 3 by the cable sheath 7 is 30 N / 300 mm to 310 N / 300 mm.

  Further, in the plane orthogonal to the extending direction of the optical fiber core wire 3, the optical fiber core in the direction (vertical direction in FIG. 1; second direction) in the direction orthogonal to the arrangement direction (first direction) of the optical element strength member 5 is shown. Notches 11 are formed on the surface of the cable sheath 7 located on both sides of the wire 3 (up and down in FIG. 1).

  In the above configuration, in the case of the optical fiber cable 1 shown in FIG. 1, the eight optical fiber core wires 3 are arranged in the hollow portion 13 of the cable sheath 7 so as to have an appropriate adhesion force as described above. The sheath 7 is controlled so as not to penetrate into the optical fiber core wire 3. The hollow portion 13 has a substantially rectangular cross section according to the arrangement of the eight optical fiber cores 3, but as described above with reference to the number and arrangement of the optical fiber cores 3 as shown in FIG. 3. It is preferable that the hollow portion 13 has a shape having an appropriate adhesion force.

  Even if the number and arrangement of the optical fiber core wires 3 are other numbers, the same is true as shown in FIGS. 3 (A) to 3 (G).

  Therefore, when the cable sheath 7 is torn from the notch portion 11 and the optical fiber core wire 3 is led out, the tear reaches the hollow portion 13 and can be easily led out. In addition, the cable 1 can be manufactured to have a small diameter, and the side pressure by the cable sheath 7 does not increase, so that the loss characteristic can be stabilized. As a result, the optical fiber cable 1 is simplified, the assembly process is eliminated, and the processing cost can be reduced.

  Moreover, what is necessary is just to provide the notch part 11 so that the surface 15 which connects notch part 11a and 11b which opposes may cross | intersect the hollow part 13 of the cable sheath 7 which accommodates the optical fiber core wire 3. FIG. In this way, especially when the number of the optical fiber cores 3 is large, the hollow portion 13 becomes large, and therefore the allowable range of the position of the notch portion 11 is wide. Can be positioned. Therefore, the manufacture of the optical fiber cable 1 can be made easier.

  The retention force of the optical fiber core wire 3 inside the cable sheath 7, that is, in the hollow portion 13, is the optical fiber cable 1 (FIG. The optical fiber core wire 3 at both ends of the cable is illustrated, but the sample length of the optical fiber cable 1 is 300 mm, and the cable sheath 7 at one end (the left end in FIG. 7) The outside is fixed by the fixing portion 17, and the optical fiber core wire 3 at the other end (right end in FIG. 7) is collectively held and pulled by the optical fiber batch holding portion 21 of the tensiometer 19. At this time, a value obtained by observing the lead-out optical fiber 3 at the terminal on the opposite side and measuring the tension when the optical fiber 3 starts to move, that is, the retention force (core pull-out force). It is.

  The optical fiber cable 1 formed so that the tensile force of the optical fiber core wire 3 is in the range of 30 N / 300 mm to 310 N / 300 mm when the sheath is extruded is not too strong and is not too weak. It is. For example, when the retention force is smaller than 310 N / 300 mm, the transmission loss is prevented from being deteriorated because the cable sheath 7 bites into the optical fiber core wire 3 and is compressed.

  On the other hand, when the retention force is larger than 30 N / 300 mm, the optical fiber core wire 3 moves downward according to gravity, the macrobending occurs at a position where the hanging position of the optical fiber cable 1 is low, and a bending loss tends to occur. This prevents the movement of the core wire during overhead wiring.

  FIG. 2 shows an optical fiber cable 1 according to a second embodiment of the present invention. The optical fiber cable 1 has a long optical element portion 9 similar to that shown in FIG. The optical fiber cable 1 further includes a long cable support line portion 27 in which the support line 23 is covered with a sheath 25. The support wire 23 is made of, for example, a steel wire. The sheath 25 is a thermoplastic resin and is formed integrally with the cable sheath 7. Therefore, the cable support line portion 27 is integrated with the optical element portion 9 in parallel via the neck portion 29. In addition, in the plane orthogonal to the extending direction of the optical fiber core wire 3, the support wire 23, the pair of optical element strength members 5 and the optical fiber core wire 3 are arranged in alignment along the first direction. .

  With this configuration, the optical fiber cable 1 is formed by integrating the long cable support line portion 27 in which the support wire 23 is covered with the sheath 25 and the optical element portion 9 through the neck portion 29 in parallel with each other. It can be used as an optical fiber drop cable and has the same effect as the effect in FIG.

  The optical fiber core 3 may be a single strand or a tape strand in addition to a plurality of strands. In particular, a 0.25 mm strand is most preferably used, but a 2-core tape core or a single core of about 0.4 to 0.9 mm is also used.

  Further, as the tensile element 5 for the optical element, a steel wire, FRP, or the like is preferably used, and a steel wire is used as the support wire 23.

  In consideration of the lead-out property of the optical fiber core wire 3, each notch portion 11 is closest to the optical fiber core wire 3 in a plane orthogonal to the extending direction of the optical fiber core wire 3 as shown in FIG. 1. It is desirable that the straight line 15 connecting the points 11a and 11b intersects the boundary line of the shape of the hole 13 (hollow part) formed in the cable sheath 7 by the optical fiber core wire 3.

  Next, a method for manufacturing the optical fiber cable 1 shown in FIG. 2 will be described.

  Referring to FIG. 4, a cross-sectional view of the extrusion head 31 is shown, and a nipple portion 33 as shown in FIG. As shown in FIG. 6, for example, a die portion 37 having a die hole 35 having substantially the same shape as the outer peripheral shape of the cross section of the optical fiber cable 1 in FIG. 2 is provided on the outer periphery of 33. In this case, projecting portions 39a and 39b for forming the notch portion 11 are provided in the die hole 35 at a position corresponding to the notch portion 11 of the cable 1 in FIG. Between this die part 37 and the said nipple part 33, the flow path 41 by which the thermoplastic resin P as a sheath is extruded is provided.

  Further, as shown in FIG. 5, the nipple portion 33 is formed with, for example, a nipple hole 43 as a through hole through which the optical fiber core wire 3 passes, and the front side of the nipple hole 43 (leftward in FIG. 5). ) Is connected to a pipe 45 as a cylindrical body extending to the die hole 35 in the extrusion direction (left direction in FIG. 4). Further, a nipple hole 47 through which the optical element strength member 5 passes is provided on both outer sides of the nipple hole 43, and a nipple hole 49 through which the support line 23 passes is formed outside (left side) of the left nipple hole 47 in FIG. Has been. In FIG. 5, the nipple hole 43 and the pipe 45 have a rectangular cross-sectional shape, but may have a round shape or other shapes depending on the number and arrangement of the optical fiber core wires 3.

  4 and FIG. 5, the optical fiber core wire 3, the two optical element strength members 5 and the support wire 23 wound around a reel (not shown) provided on the right side are drawn out and extruded. It is sent into the head 31. When the plurality of optical fiber cores 3 pass through the nipple hole 43 and the pipe 45 of the nipple portion 33 in the extrusion head 31, they are arranged in advance so as to have an arrangement structure as shown in FIG. Therefore, these eight optical fiber core wires 3 are arranged in the hollow portion 13.

  Further, the two optical element strength members 5 pass through the nipple holes 47 of the nipple portion 33, and one support line 23 passes through the nipple hole 49 in the left direction in FIGS. 4 and 5. At the same time, the molten thermoplastic resin P is extruded from the flow path 41 of the die portion 37. At this time, by adjusting the clearance between the die portion 37 and the pipe 45 of the nipple portion 33, the size of the hollow portion 13 with respect to the optical fiber core wire 3 is finely adjusted, so as shown in FIG. In addition, it is possible to obtain the optical fiber cable 1 in which the optical fiber core wire 3 has the above-described moderate retention force.

  In addition, the cross-sectional shape of the nipple hole 43 of the pipe 45 is, for example, a plurality of optical fiber cores 3 arranged in the same manner as in FIG. It is preferable to have a cross-sectional shape according to the arrangement.

  In short, the manufacturing method of the optical fiber cable 1 has the following characteristics. That is, in this manufacturing method, the extrusion head 31 is used, and this extrusion head 31 has the following.

(1) The tip portion has a truncated cone (or truncated cone) shape, and the tip surface (or truncated surface) 33a has a nipple hole 43 and a pipe 45 for allowing the optical fiber core wire 3 to pass therethrough, and a pair of A nipple portion 33 having a pair of nipple holes 47 for allowing the optical element strength member 5 to pass therethrough.
(2) A die portion 37 having a conical inner peripheral surface arranged parallel to the conical surface of the nipple portion 33 at a predetermined interval, and a sheath thermoplastic resin together with the optical fiber core wire 3 In order to form the die hole 35 for extruding P and the notch portion 11, a die portion 37 having projecting portions 39 a and 39 b projecting into the die hole 35.
Here, the cross-sectional area of the nipple hole 43 is larger than the cross-sectional area of the nipple hole 47. The nipple holes 47 are disposed on both sides of the nipple hole 43 in the first direction on the tip surface 33a. Furthermore, the protrusions 39a and 39b are provided to face each other in a second direction orthogonal to the first direction in a plane parallel to the tip surface 35a.

  In the first direction, it is desirable that the tip portions of the projecting portions 39 a and 39 b have substantially the same Cartesian coordinate value as the center of the nipple hole 43.

  And this manufacturing method has the following processes.

(1) Step of pulling out the optical fiber core 3 from the nipple hole 43 (2) Step of pulling out the optical element tensile body 5 from the nipple hole 47 (3) Heat from the die hole 35 together with the optical fiber core 3 (4) Extruding the thermoplastic resin P (4) In the state where the thermoplastic resin P surrounds the optical fiber core wire 3 and the optical element tensile member 5 in front of the die hole 35 in the extrusion direction, Step of curing and integrating the optical fiber core wire 3 and the optical element tensile member 5 Here, a step of drawing the optical fiber core wire 3 from the nipple hole 43 and an extraction of the optical element tensile member 5 from the nipple hole 47 The process and the process of extruding the thermoplastic resin P or the like from the die hole 35 are performed simultaneously.

  Moreover, according to the said manufacturing method, the optical fiber cable 1 provided with the optical fiber core wire 3, the optical element strength member 5, the sheaths 7 and 21, and the support wire 23 can be rapidly manufactured in a series of continuous processes.

  With the above configuration, the molten thermoplastic resin P pushed out from the flow path 41 between the nipple portion 33 and the die portion 37 passes through between the pipe 45 and the die hole 35 (that is, an optical fiber fed out from the nipple hole 43). Solidify (before contact with core 3). Therefore, as shown in FIG. 2, the optical fiber cable 1 having an appropriate retention force of the optical fiber core wire 3 is obtained between the optical fiber core wire 3 and the cable sheath 7 in the hollow portion 13 of the cable sheath 7. be able to.

  In addition, the optical fiber cable 1 as shown in FIG. 1 can be obtained using another dice | dies part, without supplying said support wire 23. FIG.

  Further, according to the above manufacturing method, the optical fiber cable 1 including the optical fiber core wire 3, the optical element strength member 5 and the sheath 7 can be quickly formed in a series of continuous processes as in the manufacturing method shown in FIGS. Can be manufactured.

  Next, the performance of the optical fiber cable 1 according to the embodiment of the present invention will be described in detail.

  The optical fiber cable of this embodiment shown in FIG. 2 is changed by changing the clearance between the die portion 37 and the pipe 45 of the nipple portion 33 when the optical fiber cable 1 is extruded using the manufacturing method described above. 1, the retention force of the optical fiber core 3 is 10 N / 300 mm (condition 1), 30 N / 300 mm (condition 2), 90 N / 300 mm (condition 3), 180 N / 300 mm (condition 4), 310 N / 300 mm (condition) 5), an optical fiber cable 1 of 410 N / 300 mm (condition 6) was prototyped, and the characteristics of these were evaluated. The results are shown in Table 1. These have the same configuration, that is, the shape and material, except for the internal configuration due to the difference in the drawing force of the optical fiber core wire 3.

なお、表１中の伝送損失は、波長１．５５μｍで「パルス試験法（ＯＴＤＲ法）・・・ＪＩＳＣ ６８２３の９」にて測定した。 In this optical fiber cable 1, a GFRP (Glass Fiber Reinforced Plastics) of φ0.4 mm is used for the tensile element 5 for the optical element, and a steel wire of φ1.2 mm is used for the support wire 23. The outer dimension of 9 is 2.8 mm × 5.8 mm.

The transmission loss in Table 1 was measured by a “pulse test method (OTDR method)... 9 of JISC 6823” at a wavelength of 1.55 μm.

  Further, the (maximum) movement amount with respect to the longitudinal direction of the optical fiber core wire 3 means that the sample length of the optical fiber cable 1 is 30 m as shown in FIG. 3, the outer side of the sheath 25 at one end (left end in FIG. 8) of the cable support line portion 27 is fixed by the fixing portion 51, and the cable support line portion 27 at the other end (right end in FIG. 8) is tensioned at 700 N. It is a value obtained by pulling and extending the optical fiber cable 1 at this time, observing the lead-out optical fiber core 3 and measuring the amount of movement of the optical fiber core 3. The 700 N applied load takes into account the maximum elongation assumed when the optical fiber cable 1 is laid and used.

  For example, before applying the tension, the length of the left optical fiber core 3 in FIG. 8 is L1, the length of the right optical fiber 3 is L2, and the light on the left end after the tension is applied. When the length of the fiber core wire 3 is L1 ± δ1 and the length of the optical fiber core wire 3 on the right end side is L2 ± δ2, the larger of the absolute values of movement amounts, | δ1 |, | δ2 | It is a quantity value.

  As can be seen from Table 1, when the retention force of the optical fiber core wire 3 is 10 N / 300 mm (condition 1), the transmission loss characteristic was good at 0.25 dB / km or less, but the optical fiber core wire 3 The maximum amount of movement was 45 mm, and a very large amount of movement of the optical fiber core 3 with respect to the longitudinal direction of the optical fiber cable 1 was generated.

  On the other hand, when the tensile force of the optical fiber core 3 is 410 N / 300 mm (condition 6), the maximum movement amount of the optical fiber core 3 is almost 1 mm, but the measurement result of transmission loss is 0.25 dB / km, and the increase in the loss was confirmed because the lateral pressure on the optical fiber core wire 3 increased.

  Further, when the holding force of the optical fiber core wire 3 is 30 N / 300 mm (condition 2) to 310 N / 300 mm (condition 5), the maximum movement amount of the optical fiber core wire 3 is almost 0 to 2 mm, and the loss characteristic is 0. Good at 25 dB / km or less. Therefore, by setting the retention force of the optical fiber core wire 3 in the range of 30 N / 300 mm to 310 N / 300 mm, the optical fiber cable 1 having no transmission in the longitudinal direction of the optical fiber core wire 3 and good transmission loss characteristics can be obtained. can get.

表２から分かるように、図１２の従来の光ファイバケーブル１２７はシース押出方式が充実押出であるので、光ファイバ心線１１９に対する密着力ないしは引留力が強く、光ファイバ心線１１９の移動防止になるが、側圧による伝送損失が増加する。また、図１３の従来の光ファイバケーブル１３７はシース押出方式がパイプ押出であるので、光ファイバ心線１１９に対する密着力ないしは引留力がゼロであるために、側圧がないのでケーブル製造時や敷設初期の伝送損失が良好であるが、敷設後には、重力や振動等により光ファイバ心線が移動し、局所的に曲がりや圧縮等が発生し、伝送損失の増加となる。 2 is compared with the conventional optical fiber cables 127 and 137 shown in FIGS. 12 and 13 as shown in Table 2. . These have the same configuration, that is, the shape and material, except for the configuration around the optical fiber core.

As can be seen from Table 2, since the conventional optical fiber cable 127 of FIG. 12 is a full extrusion of the sheath extrusion method, the adhesion force or the retention force with respect to the optical fiber core wire 119 is strong, and the optical fiber core wire 119 is prevented from moving. However, transmission loss due to side pressure increases. In addition, since the conventional optical fiber cable 137 of FIG. 13 uses pipe extrusion as the sheath extrusion method, there is no side pressure because the adhesion force or the retention force with respect to the optical fiber core wire 119 is zero. However, after laying, the optical fiber core wire is moved by gravity, vibration, or the like, causing local bending or compression, resulting in an increase in transmission loss.

  On the other hand, this embodiment has the following advantages.

  When the cable sheath 7 is torn from the notch portion 11 and the optical fiber core wire 3 is led out, the cable sheath 7 does not bite into the inside of the optical fiber core wire in the hollow portion 13 and can be easily led out. Can be manufactured in diameter. It can be used as an optical fiber drop cable.

  Further, since the sheath extrusion method pushes out by controlling the adhesion force or the retention force to the optical fiber core wire 3, an appropriate adhesion force or retention force can be obtained. As a result, it is possible to suppress the movement of the core wire during overhead wiring by greatly improving the retention force without impairing the transmission characteristics.

  The present invention can be widely applied to one or a plurality of strands or optical fibers 3 of a tape core.

  Since the optical fiber cable 1 obtained by this manufacturing method is extruded by controlling the adhesion force or the retention force with respect to the optical fiber core wire 3 by the sheath extrusion method, an appropriate adhesion force or retention force can be obtained. As a result, the retention force can be greatly improved without impairing the transmission characteristics, so that the core wire movement during overhead wiring can be suppressed.

  In addition, since the nipple holes 43 of the pipe 45 provided in the nipple portion 33 that allows the plurality of optical fiber cores 3 to pass therethrough have a cross-sectional shape that matches the arrangement of the plurality of optical fiber cores 3, the optical fiber core 3 Can be easily adjusted. The optical fiber cable 1 can be quickly manufactured in a series of continuous processes.

  The present invention is not limited to the above-described embodiment, and can be implemented in other modes by making appropriate modifications.

It is sectional drawing of the optical fiber cable of embodiment of this invention. It is sectional drawing of the optical fiber cable of another embodiment of this invention. (A)-(F) are the fragmentary sectional views which show the number and arrangement | sequence of an optical fiber core wire, and the shape of a hollow part. It is sectional drawing of an extrusion head part. It is a perspective view of a nipple part. It is a perspective view of a die part. It is a schematic explanatory drawing of the retention strength test method of an optical fiber core wire. It is a schematic explanatory drawing of the movement amount measuring method of an optical fiber core wire. It is state explanatory drawing of the wiring of an optical fiber cable. It is sectional drawing of the conventional optical fiber cable. It is sectional drawing of the other conventional optical fiber cable. It is sectional drawing of another conventional optical fiber cable. It is sectional drawing of another conventional optical fiber cable.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical fiber cable 3 Optical fiber core wire 5 Strength element for optical elements 7 Cable sheath 9 Optical element part 11 Notch part 13 Hollow part 15 Surface 23 Support line 25 Sheath 27 Cable support line part 29 Neck part 31 Extrusion head 33 Nipple part 35 Dice Hole 37 Die part 43 Nipple hole 45 Pipe (tubular body)

Claims (9)

An optical fiber core,
Strength members disposed on both sides of the optical fiber core along the extending direction of the optical fiber core;
A cable sheath for covering the optical fiber core and the tensile body, and cables on both sides of the optical fiber core in a second direction perpendicular to the first direction connecting the tensile bodies in a plane perpendicular to the extending direction. Cable sheaths each having at least one notch formed on the surface of the sheath;
Having a long optical element portion comprising
An optical fiber cable, wherein the optical fiber has a retention force in a range of 30 N / 300 mm to 310 N / 300 mm. 2. The optical fiber cable according to claim 1, comprising a long cable support line portion in which a support line is covered with a sheath, the cable support line portion being arranged in parallel with and integrated with the optical element portion. The optical fiber cable according to claim 1, wherein the optical fiber core includes one or a plurality of strands or a tape core. A straight line connecting points closest to the optical fiber core wire of the notches in a plane perpendicular to the extending direction intersects a boundary line of a hole shape formed in the sheath by the optical fiber core wire. Item 4. The optical fiber cable according to any one of Items 1 to 3. The optical fiber cable according to claim 4, wherein the straight line is parallel to the second direction in the plane. A step of running an optical fiber core and a tensile body disposed on both sides of the optical fiber core along a direction in which the optical fiber core is stretched to supply the extrusion head;
Extruding a thermoplastic resin into the extrusion head;
A step of forming an optical element portion in which the optical fiber core and the tensile body are covered with a cable sheath, wherein the clearance between the die portion and the nipple portion constituting the extrusion head is determined by the retention force of the optical fiber core wire. A step of adjusting to be in a range of 30 N / 300 mm to 310 N / 300 mm, and on both sides of the optical fiber core wire in a second direction orthogonal to the first direction connecting the strength members in a plane perpendicular to the stretching direction. Forming an optical element portion including a step of forming a notch portion on the surface of the cable sheath;
A method for manufacturing an optical fiber cable. An optical fiber core, a tensile body disposed on both sides of the optical fiber core along the extending direction of the optical fiber core, and a step of feeding the support wires to the extrusion head,
Extruding a thermoplastic resin into the extrusion head;
An optical element portion in which the optical fiber core wire and the tensile body are covered with a cable sheath, and a cable support wire portion in which the support wire is covered with a sheath are arranged in parallel and integrally formed, Adjusting the clearance between the die portion and the nipple portion constituting the extrusion head so that the holding force of the optical fiber core is in a range of 30 N / 300 mm to 310 N / 300 mm; and the extending direction of the optical fiber core Forming a notch portion on the surface of the cable sheath on both sides of the optical fiber core wire in the second direction orthogonal to the first direction in the plane perpendicular to the first direction;
A method for manufacturing an optical fiber cable. 7. A plurality of optical fiber cores are arranged and allowed to pass through nipple holes of a cylindrical body provided in the nipple portion, and the nipple holes have a cross-sectional shape matching the arrangement of the plurality of optical fiber cores. Or a method for producing an optical fiber cable according to 7. 9. The method of manufacturing an optical fiber cable according to claim 6, wherein the step of supplying the optical fiber core wire / strength member to the extrusion head and the step of supplying the thermoplastic resin to the extrusion head are performed simultaneously. .

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