JP6314162B2 - Retractable optical cable, optical fiber cable laying method, and retractable optical cable manufacturing method - Google Patents

Description

  The present invention relates to a retractable optical cable, an optical fiber cable laying method, and a retractable optical cable manufacturing method.

  In order to protect the optical fiber cable, it is known to store the optical fiber cable in a protective tube or the like (see Patent Documents 1 to 3).

JP 2001-83332 A Japanese Patent Laid-Open No. 2003-140010 JP, 2014-120414, A

  When the gap between the optical fiber cable and the protective tube for storing the optical fiber cable is large as in the cables described in Patent Documents 1 and 2, the position of the neutral line of the bending of the optical fiber cable and the protective tube is different. Thus, there is a difference in wire length between the state in which the protective tube containing the optical fiber cable is wound around the drum and the state in which the protective tube is pulled out from the drum. As a result, there is a possibility that a force is applied to the optical fiber cable when the optical fiber cable is laid, and the optical fiber cable may be damaged or the life of the optical fiber cable may be reduced.

  When the cable is arranged in the center of the protective tube by arranging the interposition as described in Patent Document 3, it is possible to match the position of the neutral line of the bending of the optical fiber cable and the protective tube. The line length difference between the cable and the protective tube is suppressed. However, in the structure described in Patent Document 3, since the protective tube is interposed, it becomes difficult to store other cables or take out the optical fiber cable from the protective tube, and the workability is lowered.

  It is an object of the present invention to provide a storage type optical cable that can suppress a difference in wire length between an optical fiber cable and a storage tube and that can be easily laid.

A main invention for achieving the above object is to provide an optical fiber, an outer sheath covering the optical fiber, an optical fiber cable including a tension member embedded in the outer sheath, and a storage housing the optical fiber cable. The optical fiber cable is housed in a spiral shape along the inner wall of the housing tube.

  Other characteristics of the present invention will be made clear by the description and drawings described later.

  ADVANTAGE OF THE INVENTION According to this invention, while being able to suppress the wire length difference of an optical fiber cable and a storage tube, the workability | operativity at the time of laying of an optical fiber cable can be improved.

FIG. 1A is a cross-sectional view of the retractable optical cable 1 according to the first embodiment. FIG. 1B is a perspective view of the retractable optical cable 1 of the first embodiment. FIG. 2 is an explanatory diagram of the intermittently fixed optical fiber tape 12. FIG. 3A is a cross-sectional explanatory view of each part of the retractable optical cable 1 of the first embodiment. FIG. 3B is an explanatory diagram of the position of the neutral line when the retractable optical cable 1 of the first embodiment is wound around a drum. FIG. 4 is a schematic explanatory diagram of a method for taking out the optical fiber cable 10. FIG. 5 is an explanatory diagram of another manufacturing method of the retractable optical cable 1. FIG. 6 is a cross-sectional view of the optical fiber cable 10 ′ accommodated in the retractable optical cable 1 of the second embodiment. FIG. 7A is an explanatory diagram of a retractable optical cable 1 of a comparative example. FIG. 7B is an explanatory diagram of the position of the neutral line when the retractable optical cable 1 of the comparative example is wound around a drum.

  At least the following matters will be apparent from the description and drawings described below.

  An optical fiber cable and a storage tube storing the optical fiber cable are provided, and the optical fiber cable is spirally stored along the inner wall of the storage tube. It becomes. According to such a storage type optical cable, a difference in wire length between the optical fiber cable and the storage tube can be suppressed, and workability at the time of laying the optical fiber cable can be improved.

  The optical fiber cable has elasticity against bending deformation, and is preferably in contact with the inner wall by an elastic force generated by being stored in a spiral shape. This stabilizes the position of the optical fiber cable inside the storage tube.

  The optical fiber cable preferably has at least two tension members. Thereby, the position of the optical fiber cable inside the storage tube is particularly stabilized.

  The optical fiber cable is preferably twisted according to the helical pitch of the optical fiber cable. Thereby, the position of the optical fiber cable inside the storage tube is particularly stabilized.

  The optical fiber cable is preferably twisted so that one side of the optical fiber cable is in contact with the inner wall as viewed from the neutral plane. As a result, the neutral plane of the bending of the optical fiber cable faces the inner wall, so that the elastic force acts so that the optical fiber cable spreads toward the inner wall, and the position of the optical fiber cable inside the storage tube is Especially stable.

  The optical fiber cable preferably includes a plurality of optical fibers, and the plurality of optical fibers are preferably arranged in a twisted state inside the optical fiber cable. Thereby, the line length difference between optical fibers can be suppressed.

  The retractable optical cable is preferably wound around a drum, and the helical pitch of the optical fiber cable is preferably shorter than the circumferential length of the drum. Thereby, the local line length difference can be canceled while the retractable optical cable is wound once around the drum.

  It is desirable that the optical fiber cable can be taken out from the storage tube by twisting the optical fiber cable twisted in a predetermined direction and spirally received in the storage tube in a direction opposite to the predetermined direction. This facilitates the laying operation of the optical fiber cable.

  The end of the optical fiber cable is preferably fixed to the storage tube. As a result, the twist and spiral of the optical fiber cable need not be unwound.

  It is desirable that irregularities be formed on the inner wall. Thereby, since a contact area can be reduced, the operation | work which takes out an optical fiber cable from a storage tube becomes easy.

  An optical fiber cable; and a storage tube that stores the optical fiber cable; and a storage-type optical cable in which the optical fiber cable is spirally stored along an inner wall of the storage tube; By twisting the cable, a method of laying the optical fiber cable is disclosed in which the spiral of the optical fiber cable is unwound and the optical fiber cable is pulled out of the storage tube. According to such a laying method, the optical fiber cable spirally stored in the storage tube can be easily pulled out from the storage tube.

  Preparing a drum around which an optical fiber cable is wound, drawing the optical fiber cable from the drum along the axial direction of the drum, and inserting the optical fiber cable drawn from the drum into a storage tube Thus, a method for manufacturing a storage type optical cable that spirally stores the optical fiber cable along the inner wall of the storage tube becomes clear. According to such a manufacturing method, it is possible to easily manufacture a storage type optical cable in which the spiral pitch and twist pitch of the optical fiber cable are adjusted.

  It is desirable that the drum is rotated in the axial direction when the optical fiber cable is pulled out from the drum along the axial direction of the drum. This facilitates adjustment of the helical pitch and twist pitch of the optical fiber cable.

=== First Embodiment ===
<Comparative example>
FIG. 7A is an explanatory diagram of a retractable optical cable 1 of a comparative example. The upper view of FIG. 7A is a view of the retractable optical cable 1 viewed from the side (viewed from the vertical direction of the longitudinal direction). The lower view of FIG. 7A is a cross-sectional view of the retractable optical cable 1. In the comparative example, the optical fiber cable 10 is stored linearly along the longitudinal direction of the storage tube 20.
As shown in the lower part of FIG. 7A, the neutral line of bending of the storage tube 20 is a line passing through the center of the storage tube 20. Further, the neutral line of bending of the optical fiber cable 10 is a line passing through the center of the optical fiber cable 10. When two tension members 15 are embedded in the optical fiber cable 10, the bending neutral line of the optical fiber cable 10 is a line connecting the centers of the two tension members 15. As shown in the figure, when the optical fiber cable 10 is arranged so as to contact the inner wall 21 of the storage tube 20, the position of the bending neutral line of the storage tube 20 and the position of the bending neutral line of the optical fiber cable 10 are different. ing.

  FIG. 7B is an explanatory diagram of the position of the neutral line when the retractable optical cable 1 of the comparative example is wound around a drum. When the storage type optical cable 1 of the comparative example is wound around the drum, the optical fiber cable 10 is wound inside the storage tube 20 in a state of being close to the inner side (drum side). As a result, the neutral line of the bending of the optical fiber cable 10 is The storage tube 20 is positioned on the inner side (drum side) of the bending neutral line. Further, when the storage type optical cable 1 of the comparative example is wound around the drum, the optical fiber cable 10 may be wound inside the storage tube 20 in a state of being close to the outside (the side opposite to the drum). In this case, the neutral line of the bending of the optical fiber cable 10 is positioned outside the neutral line of bending of the storage tube 20 (on the side opposite to the drum).

  Thus, if the position of the neutral line of the storage tube 20 and the optical fiber cable 10 when wound around the drum is different, the lengths of the storage tube 20 and the optical fiber cable 10 for one circumference of the drum are different. It will be. For example, in the state shown in FIG. 7B, the length of the optical fiber cable 10 for one turn of the drum is shorter than the length of the storage tube 20 for one turn of the drum. As a result, when the retractable optical cable 1 is pulled out from the drum, a difference in wire length occurs between the retractable tube 20 pulled out from the drum and the optical fiber cable 10. In particular, when the retractable optical cable 1 in the state shown in FIG. 7B is pulled out from the drum, the optical fiber cable 10 is pulled into the accommodating tube 20. As a result, a tensile force may be applied to the optical fiber cable 10, which may damage the optical fiber cable 10 or reduce the life of the optical fiber cable 10.

<Description of components>
FIG. 1A is a cross-sectional view of the retractable optical cable 1 according to the first embodiment. FIG. 1B is a perspective view of the retractable optical cable 1 of the first embodiment.

  The storage type optical cable 1 includes an optical fiber cable 10 and a storage tube 20. Since the optical fiber cable 10 is housed in the housing tube 20, it is difficult for an external force such as a lateral pressure to be applied to the optical fiber cable 10, and thus the retractable optical cable 1 is suitable for being embedded in the soil, for example. As will be described later, the retractable optical cable 1 of the present embodiment differs from the comparative example (see FIG. 7A) in that the optical fiber cable 10 is spirally accommodated along the inner wall 21 of the accommodating tube 20. .

  The optical fiber cable 10 is a cable having an optical fiber 11. The optical fiber 11 includes an optical fiber core and an optical fiber. In the optical fiber cable 10 of the first embodiment, a bundle of a plurality of optical fibers 11 is covered with a press-wound tape 13, and the outer side thereof is covered with a jacket 14. A tension member 15 is embedded in the jacket 14. A lip cord 16 is also embedded in the jacket 14.

Here, the plurality of optical fibers 11 are formed by collecting a plurality of intermittently fixed optical fiber tapes 12. FIG. 2 is an explanatory diagram of the intermittently fixed optical fiber tape 12.
The intermittently fixed type optical fiber tape 12 is an optical fiber tape 12 in which a plurality (here, four) of optical fibers 11 are connected in parallel. Two adjacent optical fibers 11 are connected by a connecting portion 12A. Between the two adjacent optical fibers 11, a plurality of connecting portions 12A are intermittently arranged in the longitudinal direction. The plurality of connecting portions 12A of the intermittently fixed optical fiber tape 12 are intermittently arranged two-dimensionally in the longitudinal direction and the tape width direction. A region other than the connecting portion 12A between the two adjacent optical fibers 11 is a non-connecting portion 12B. In the non-connecting portion 12B, adjacent two optical fibers 11 are not restrained. As a result, the intermittently fixed optical fiber tape 12 can be rounded into a cylindrical shape (bundle shape) or folded, and a large number of optical fibers 11 can be bundled at high density.
The plurality of optical fibers 11 may not be configured from the intermittently fixed optical fiber tape 12. For example, instead of the intermittently fixed type optical fiber tape 12, a single-core optical fiber 11 may be used.

  The presser winding tape 13 is a member that wraps the plurality of optical fibers 11. As the presser winding tape 13, a polyimide tape, a polyester tape, a polypropylene tape, a polyethylene tape, or the like is used. In addition, a nonwoven fabric can be used as the presser winding tape 13. In this case, the nonwoven fabric used is a tape formed of polyimide, polyester, polypropylene, polyethylene or the like. In addition, the nonwoven fabric may be a material to which water-absorbing powder or the like is attached and applied, or a surface processed for that purpose. The presser winding tape 13 may be a non-woven fabric bonded with a film such as a polyester film.

  The jacket 14 is a member that covers the optical fiber 11 (and the presser winding tape 13). As a material of the jacket 14, for example, a resin such as polyvinyl chloride (PVC), polyethylene (PE), nylon (trademark registered), ethylene fluoride, or polypropylene (PP) can be used. Further, as the material of the outer jacket 14, for example, a polyolefin compound containing a hydrated metal compound such as magnesium hydroxide or aluminum hydroxide as a flame retardant can also be used.

The tension member 15 is a member (strength member) that resists the contraction of the outer cover 14 and suppresses distortion and bending applied to the optical fiber 11 due to the contraction of the outer cover 14. The tension member 15 is a linear member, and is embedded in the outer jacket 14 along the longitudinal direction of the optical fiber cable 10. As the material of the tension member 15, a non-metallic material or a metallic material can be used. Non-metallic materials such as glass FRP (GFRP), aramid fiber reinforced plastic (KFRP) reinforced with Kevlar (registered trademark), and fiber reinforced plastic (FRP) such as polyethylene fiber reinforced plastic reinforced with polyethylene fiber can be used. is there. As the metallic material, a metal wire such as a steel wire can be used.
The retractable optical cable 1 of the present embodiment may be buried in the ground together with the electric cable. When the optical fiber cable 10 is laid close to the electric cable as described above, the influence of electromagnetic induction or the like is exerted. In consideration, it is desirable that the tension member 15 is made of a non-metallic material. In the present embodiment, glass FRP (GFRP) is used as the tension member 15.

  In the present embodiment, the optical fiber cable 10 has two tension members 15. The two tension members 15 are arranged one on each side so as to sandwich the accommodating portion in which the optical fiber 11 is accommodated.

  The tension member 15 is a member having a higher elastic modulus than other components. Since such a tension member 15 is embedded in the jacket 14, the optical fiber cable 10 has elasticity against bending deformation. When the optical fiber cable 10 includes the two tension members 15 as in the present embodiment, the optical fiber cable 10 is easily bent in a specific direction and is difficult to bend in the other directions (the two tension members 15). The cross-sectional secondary moment of the optical fiber cable 10 in the direction in which the optical fibers are arranged differs from the cross-sectional secondary moment of the optical fiber cable 10 in the other directions). In other words, the elastic property with respect to the bending deformation of the optical fiber cable 10 becomes an elastic property like a long and thin leaf spring having the width of the two tension members 15. For this reason, when the optical fiber cable 10 has the two tension members 15, the neutral line (neutral surface) of the bending of the optical fiber cable 10 is a line connecting the centers of the two tension members 15.

  The lip cord 16 is a string (tearing string) used for tearing the outer jacket 14. By pulling the lip cord 16, the operator can tear the outer cover 14, peel the outer cover 14, and take out the optical fiber 11 in the optical fiber cable 10. The lip cord 16 is vertically attached to the periphery of the housing portion in which the optical fiber 11 is housed, and is embedded in the jacket 14 or disposed between the jacket 14 and the presser winding tape 13. . As the lip cord 16, for example, a fiber such as polyester, polyimide, or aramid, a fiber assembly, or a fiber impregnated with a resin can be used. However, the optical fiber cable 10 may not have the lip cord 16.

  The storage tube 20 is a tube for storing the optical fiber cable 10. By storing the optical fiber cable 10 in the storage tube 20, it is possible to suppress a lateral pressure from being applied to the optical fiber cable 10 when the retractable optical cable 1 is embedded in, for example, soil. The storage tube 20 has a hollow cylindrical shape, and a storage space is formed inside. The inner diameter of the storage tube 20 is larger than the outer diameter of the optical fiber cable 10. For example, in this embodiment, the outer diameter of the optical fiber cable 10 is 8 to 15 mm, whereas the inner diameter of the storage tube 20 is 30 mm. A gap is formed between the inner wall 21 of the storage tube 20 and the jacket 14 of the optical fiber cable 10. The storage tube 20 has enough elasticity to be wound around the drum.

  It is desirable that the inner wall 21 of the storage tube 20 has irregularities. Thereby, since the contact area of the inner wall 21 of the storage tube 20 and the optical fiber cable 10 can be reduced, the work of taking out the optical fiber cable 10 from the storage tube 20 becomes easy. In the present embodiment, a corrugated tube having a corrugated wall surface is used as the storage tube 20, but the concavities and convexities are not shown in order to simplify the drawing. It should be noted that the inner wall 21 of the storage tube 20 does not have to be uneven.

<Arrangement of optical fiber cable 10>
FIG. 3A is a cross-sectional explanatory view of each part of the retractable optical cable 1 of the first embodiment. The upper figure is a view of the retractable optical cable 1 as viewed from the side, and the lower figure is a sectional view of each part of the upper figure. The lower view of FIG. 3A shows the arrangement of the optical fiber cable 10 in each cross section. FIG. 3B is an explanatory diagram of the position of the neutral line when the retractable optical cable 1 of the first embodiment is wound around a drum.

  In the retractable optical cable 1 of the present embodiment, the optical fiber cable 10 is spirally accommodated along the inner wall 21 of the accommodating tube 20 as shown in FIG. 3A. As a result, as shown in FIG. 3B, when the retractable optical cable 1 is wound around the drum, the average of the neutral line of bending of the optical fiber cable 10 is substantially the same as the position of the neutral line of bending of the storage tube 20. . In this embodiment, since the position of the neutral line of the storage tube 20 and the optical fiber cable 10 when the storage type optical cable 1 is wound around the drum substantially coincides with each other, the storage tube 20 and the optical fiber cable 10 in one round of the drum Can be suppressed. Therefore, in this embodiment, even if the retractable optical cable 1 in the state shown in FIG. 3B is pulled out from the drum, the difference in wire length between the retractable tube 20 and the optical fiber cable 10 can be suppressed.

  As shown in the lower diagram of FIG. 3A, the optical fiber cable 10 contacts the inner wall 21 of the storage tube 20. This is because the optical fiber cable 10 bent in a spiral shape tends to spread outward due to the elastic force of the tension member 15 of the optical fiber cable 10. Thus, if the optical fiber cable 10 has elasticity against bending deformation, the optical fiber cable 10 comes into contact with the inner wall 21 of the storage tube 20 by the elastic force generated by being stored in a spiral shape. This stabilizes the position of the optical fiber cable 10 inside the storage tube 20 without bonding the optical fiber cable 10 and the inner wall 21 of the storage tube 20 with an adhesive or the like (the optical fiber cable 10 is connected to the storage tube). It becomes difficult to be pulled out from 20). Further, since it is not necessary to join the optical fiber cable 10 and the inner wall 21 of the storage tube 20 with an adhesive or the like, the operation becomes easy when the optical fiber cable 10 is taken out from the storage tube 20 as will be described later.

  In addition, the optical fiber cable 10 of the present embodiment has two tension members 15. For this reason, the optical fiber cable 10 has an elastic property like an elongated leaf spring having a width of the two tension members 15. In this case, the optical fiber cable 10 bent in a spiral shape tends to spread outward like an elongated leaf spring bent in a spiral shape.

  As described above, in order to house the optical fiber cable 10 having elastic properties like an elongated leaf spring in the housing tube 20 spirally by the two tension members 15, the optical fiber cable 10 has a helical pitch P <b> 1 ( It is desirable to be twisted according to FIG. 1B). The helical pitch is the length in the longitudinal direction of the storage tube 20 until the optical fiber cable 10 is arranged for one turn in the circumferential direction of the inner wall 21. Specifically, the optical fiber cable 10 is twisted by one rotation (360 degrees) for each helical pitch P1 (see FIG. 1B). As described above, the optical fiber cable 10 is twisted according to the helical pitch P <b> 1, so that the neutral plane of the bend of the optical fiber cable 10 (a line connecting the centers of the two tension members 15) faces the inner wall 21. Therefore, an elastic force acts so that the optical fiber cable 10 spreads toward the inner wall 21 of the storage tube 20 and the position of the optical fiber cable 10 inside the storage tube 20 is particularly stable.

  In other words, in this embodiment, since the optical fiber cable 10 is twisted by one rotation (360 degrees) for each spiral pitch P1 (see FIG. 1B), the optical fiber cable 10 is viewed from the neutral plane. The optical fiber cable 10 is twisted so that the side contacts the inner wall 21 of the storage tube 20. Thereby, the leaf spring surface of the optical fiber cable 10 having elastic properties like a thin leaf spring (neutral surface of the bending of the optical fiber cable 10: a line connecting the centers of the two tension members 15) is the inner wall 21. Therefore, the elastic force acts so that the optical fiber cable 10 spreads toward the inner wall 21 of the storage tube 20, and the position of the optical fiber cable 10 inside the storage tube 20 is particularly stable.

  When the optical fiber cable 10 is twisted so that one side is in contact with the inner wall 21 of the storage tube 20 when viewed from the neutral plane of the bending of the optical fiber cable 10, the optical fiber cable 10 is always on the outside. Will be arranged in a spiral. When the optical fiber cable 10 includes a plurality of optical fibers 11, if the specific optical fiber 11 is always arranged outside (or inside) the other optical fibers 11, the distance between the optical fibers 11 Therefore, a line length difference will occur. Therefore, when the optical fiber cable 10 is twisted according to the helical pitch P1, a plurality of optical fibers 11 accommodated in the optical fiber cable 10 are provided in order to suppress a difference in line length between the optical fibers 11. It is desirable to be twisted. In addition, the some optical fiber 11 may be twisted by one direction, and may be twisted by SZ shape.

  As shown in FIG. 3B, the bending neutral line of the optical fiber cable 10 alternates between the inner side and the outer side of the bending neutral line of the storage tube 20. In the region inside the bending neutral line of the optical fiber cable 10 than the bending neutral line of the storage tube 20, the length of the optical fiber cable 10 wound around the drum (the length in the longitudinal direction of the storage optical cable 1). Is shorter than the storage tube 20. Conversely, in a region where the neutral line of the bending of the optical fiber cable 10 is outside the neutral line of bending of the storage tube 20, the length of the optical fiber cable 10 wound around the drum (in the longitudinal direction of the storage optical cable 1). Length) is longer than the storage tube 20. Such a local difference in line length is desirably canceled while the retractable optical cable 1 is wound around the drum once. Therefore, in the present embodiment, the spiral pitch P1 of the optical fiber cable 10 (see FIG. 1B) is used to cancel the difference in wire length between the optical fiber cable 10 and the storage tube 20 while the retractable optical cable 1 is wound around the drum. ) Is shorter than the circumference of the drum. Specifically, in this embodiment, since the diameter of the drum is 600 mm and the helical pitch P1 is 1 meter, the helical pitch P1 of the optical fiber cable 10 is larger than the peripheral length of the drum (about 1.88 meters). It is set short. Since the optical fiber cable 10 and the inner wall 21 of the storage tube 20 are not joined to each other, the optical fiber cable 10 is allowed to slightly deviate from the inner wall 21, so that the storage type optical cable 1 is used as a drum. When winding or retracting the retractable optical cable 1 from the drum, it is possible to cancel the local line length difference.

<Laying optical fiber cable 10>
When the optical fiber cable 10 is laid, the optical fiber cable 10 is taken out from the storage tube 20 of the above-described storage type optical cable 1.

  FIG. 4 is a schematic explanatory diagram of a method for taking out the optical fiber cable 10. As already described, the optical fiber cable 10 is spirally accommodated in the storage tube 20, and the optical fiber cable 10 is twisted in a predetermined direction (twist direction) according to the spiral pitch.

  When taking out the optical fiber cable 10, the operator twists the optical fiber cable 10 in a direction opposite to the twisting direction of the optical fiber cable 10 that is twisted and arranged inside the storage tube 20. That is, the operator twists the optical fiber cable 10 in a direction in which the end of the optical fiber cable 10 is brought closer to the twisted state of the optical fiber cable 10 on the back side than the end. Thereby, as the twist of the optical fiber cable 10 inside the storage tube 20 is eliminated, the spiral is unwound, and finally, the optical fiber cable 10 arranged spirally inside the storage tube 20 is straight. It becomes a shape. Since the optical fiber cable 10 that is linear does not have a force that spreads toward the inner wall 21 of the storage tube 20, the operator can easily pull out the optical fiber cable 10 from the storage tube 20. .

As already described, in this embodiment, a corrugated tube having a corrugated wall surface is used as the storage tube 20. Since the contact area between the inner wall 21 of the storage tube 20 and the optical fiber cable 10 can be reduced by the unevenness of the inner wall 21 of the corrugated tube, the work of taking out the optical fiber cable 10 from the storage tube 20 is facilitated.
In particular, since the corrugated tube has the concave and convex portions of the inner wall 21 arranged alternately along the longitudinal direction of the storage tube 20, when the optical fiber cable 10 becomes linear, the convex portion of the inner wall 21 that comes into contact with the optical fiber cable 10. A concave portion is arranged between the convex portion and the convex portion. For this reason, if the unevenness | corrugations of the inner wall 21 are arrange | positioned alternately along the longitudinal direction of the storage tube 20, when the optical fiber cable 10 is taken out, the contact area of the inner wall 21 of the storage tube 20 and the optical fiber cable 10 is ensured. This is advantageous because it can be reduced.

  As described above, when the twist of the optical fiber cable 10 is eliminated, the spiral of the optical fiber cable 10 can be unwound. For this reason, when it is desired to continuously store the optical fiber cable 10 in the inside of the storage tube 20, it is not desirable that the twist of the optical fiber cable 10 is unwound. Therefore, the end portion of the optical fiber cable 10 is preferably fixed to the storage tube 20 by a fixing means such as a tape or an adhesive. Thereby, the position of the optical fiber cable 10 inside the storage tube 20 is stabilized. When taking out the optical fiber cable 10, the operator may remove the fixing means at the end of the optical fiber cable 10 and then twist the end of the optical fiber cable 10 as described above.

<Method for Manufacturing Retractable Optical Cable 1>
As a first manufacturing method of the retractable optical cable 1, a storage tube 20 having a predetermined length (for example, 100 meters) is first prepared, and the optical fiber cable 10 is inserted into the storage tube 20 to temporarily connect the optical fiber cable 10. There is a method in which the optical fiber cable 10 is spirally arranged inside the storage tube 20 by twisting the optical fiber cable 10 inside the storage tube 20 after being arranged in a straight line. 4 is a method of manufacturing the retractable optical cable 1 by arranging the optical fiber cable 10 in a spiral shape inside the storage tube 20 in the reverse order to the method of taking out the optical fiber cable 10 shown in FIG.

FIG. 5 is an explanatory diagram of another manufacturing method of the retractable optical cable 1.
As shown on the left side in the figure, an optical fiber cable drum 30 around which the optical fiber cable 10 is wound is prepared. Since the neutral line of the bending of the optical fiber cable 10 is a line connecting the centers of the two tension members 15, two cross sections of the optical fiber cable 10 wound around the optical fiber cable drum 30 have two The direction in which the tension members 15 are arranged is the axial direction of the cylindrical optical fiber cable drum 30. As shown in the figure, when the optical fiber cable 10 is pulled out along the axial direction of the cylindrical optical fiber cable drum 30, the optical fiber cable 10 is twisted and bent into a spiral shape. If the optical fiber cable 10 drawn in this way is inserted into the storage tube 20, the storage type optical cable 1 in which the optical fiber cable 10 is spirally arranged inside the storage tube 20 can be manufactured. According to such a manufacturing method, the spiral pitch P1 (and twist pitch) of the optical fiber cable 10 can be easily adjusted. Further, by rotating the cylindrical optical fiber cable drum 30 in the axial direction and pulling out the optical fiber cable 10 along the axial direction of the optical fiber cable drum 30, the spiral pitch P1 of the optical fiber cable 10 (and It is also possible to arbitrarily adjust the (twist pitch).

  Instead of inserting the optical fiber cable 10 into the storage tube 20, the storage tube 20 is configured by two halved members, and the two halved members are joined while accommodating the optical fiber cable 10. The mold optical cable 1 may be manufactured. In addition, a cylindrical storage tube 20 having a slit in the longitudinal direction is prepared, and the optical fiber cable 10 is arranged inside the storage tube 20 by inserting the optical fiber cable 10 through the slit to manufacture the storage type optical cable 1. You may do it.

=== Second Embodiment ===
The optical fiber cable spirally stored in the storage tube 20 of the storage type optical cable 1 is not limited to the optical fiber cable 10 of the first embodiment. For example, the optical fiber cable may not have the plurality of optical fibers 11. Further, the optical fiber cable may not have the presser winding tape 13 or the lip cord 16. The cross-sectional shape of the optical fiber cable is not limited to a circular shape.

  FIG. 6 is a cross-sectional view of the optical fiber cable 10 ′ accommodated in the retractable optical cable 1 of the second embodiment. The optical fiber cable 10 ′ of the second embodiment is a drop cable (or indoor cable), and includes one optical fiber 11 ′, two tension members 15 ′, and a jacket 14 ′ covering them. Have. The cross section of the optical fiber cable 10 'is flat. Notches 14 'are formed on both sides of the flat optical fiber cable 10'. The optical fiber cable 10 ′ may include a plurality of optical fibers 11. Further, when the optical fiber cable 10 ′ is a drop cable, the support line may be connected.

  Also in the second embodiment, the optical fiber cable 10 ′ is housed in a spiral shape along the inner wall 21 of the housing tube 20, whereby the housing optical cable 1 is configured. Thereby, similarly to the first embodiment, even if the retractable optical cable 1 is pulled out from the drum, a difference in wire length between the storage tube 20 and the optical fiber cable 10 ′ can be suppressed.

  Also in the second embodiment, since the optical fiber cable 10 ′ has the tension member 15 ′, it has elasticity against bending deformation, and comes into contact with the inner wall 21 by the elastic force generated by being housed in a spiral shape. It will be. For this reason, also in the second embodiment, the position of the optical fiber cable 10 ′ inside the storage tube 20 is stabilized (the optical fiber cable 10 ′ is difficult to be pulled out from the storage tube 20).

  Also in the second embodiment, the optical fiber cable 10 ′ has two tension members 15 ′, and the optical fiber cable 10 ′ is easy to bend in a specific direction and is difficult to bend in other directions. Become. Therefore, also in the second embodiment, the optical fiber cable 10 ′ bent in a spiral shape tends to spread outward like a long and thin leaf spring bent in a spiral shape. The position of the optical fiber cable 10 ′ is particularly stable.

  In the second embodiment, the optical fiber cable 10 ′ is easily bent in a specific direction and is difficult to bend in other directions. Therefore, the optical fiber cable 10 ′ is twisted according to the helical pitch P1. It is desirable.

=== Other Embodiments ===
The above-described embodiments are for facilitating the understanding of the present invention, and are not intended to limit the present invention. The present invention can be modified and improved without departing from the gist thereof, and it goes without saying that the present invention includes equivalents thereof.

1 Retractable optical cable,
10 optical fiber cable,
11 optical fiber, 12 optical fiber tape,
12A connection part, 12B non-connection part,
13 Presser tape, 14 Outer jacket,
15 tension member, 16 lip cord,
20 storage tube, 21 inner wall,
30 Drum for optical fiber cable

Claims (13)

An optical fiber, a jacket covering the optical fiber, and an optical fiber cable including a tension member embedded in the jacket ;
A storage tube containing the optical fiber cable;
With
The optical fiber cable is housed in a spiral shape along the inner wall of the housing tube. The retractable optical cable according to claim 1,
The optical fiber cable has elasticity against bending deformation, and is in contact with the inner wall by an elastic force generated by being stored in a spiral shape. The retractable optical cable according to claim 1 or 2,
The optical fiber cable, housing type optical cable comprises said tension member at least two. The retractable optical cable according to claim 3,
The optical fiber cable is twisted according to the helical pitch of the optical fiber cable, and is a retractable optical cable. The retractable optical cable according to claim 4,
A retractable optical cable, wherein the optical fiber cable is twisted so that one side of the optical fiber cable is in contact with the inner wall when viewed from a neutral neutral plane. The retractable optical cable according to claim 4 or 5,
The optical fiber cable has a plurality of optical fibers,
The housing type optical cable, wherein the plurality of optical fibers are arranged in a twisted state inside the optical fiber cable. The retractable optical cable according to any one of claims 4 to 6,
The retractable optical cable is wound around a drum,
The retractable optical cable, wherein the helical pitch of the optical fiber cable is shorter than a peripheral length of the drum. The retractable optical cable according to any one of claims 4 to 7,
The optical fiber cable can be taken out from the storage tube by twisting the optical fiber cable that is twisted in a predetermined direction and spirally received in the storage tube in a direction opposite to the predetermined direction. Retractable optical cable. The retractable optical cable according to any one of claims 4 to 8,
The optical fiber cable has an end portion fixed to the storage tube. The retractable optical cable according to any one of claims 1 to 9,
A retractable optical cable, wherein the inner wall is uneven. An optical fiber, an outer sheath covering the optical fiber, an optical fiber cable including a tension member embedded in the outer sheath, and a storage tube storing the optical fiber cable, wherein the optical fiber cable is Preparing a retractable optical cable that is spirally stored along the inner wall of the storage tube;
Untwisting the fiber optic cable by twisting the fiber optic cable; and
A method of laying an optical fiber cable, wherein the optical fiber cable is pulled out from the storage tube. Prepare a drum around which the optical fiber cable is wound,
Pulling the optical fiber cable out of the drum along the axial direction of the drum; and
A method of manufacturing a retractable optical cable, wherein the optical fiber cable is spirally stored along the inner wall of the storage tube by inserting the optical fiber cable drawn from the drum into the storage tube. It is a manufacturing method of the accommodation type optical cable according to claim 12,
A method for producing a retractable optical cable, wherein the drum is rotated in the axial direction when the optical fiber cable is pulled out from the drum along the axial direction of the drum.

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