Fiber optic cable

Abstract

This optical fiber cable comprises: an optical fiber tape (20) configured by intermittently bonding two or more optical fiber core wires (10) by means of an adhesive part (15) lined along the longitudinal direction of the optical fiber core wires; and a cover part (50) that has a projection portion (32) in the inner wall and that covers the optical fiber tape. The projection portion abuts against the adhesive part and blocks movement of the optical fiber tape in the longitudinal direction.

Description

Technical Field

[0001] The present disclosure relates to an optical fiber cable.

Background Art

[0002] Patent Document 1 discloses a multi-core optical fiber cable in which a plurality of single-core coated optical fibers are straight or twisted and assembled, an identification thread or tape is wound around the outer periphery thereof, and further an outer coating is provided on the outer periphery of a plurality of optical fibers straight or twisted and assembled after winding the identification thread or tape.

[0003] Patent Document 2 discloses an optical fiber in which a core composed of a plurality of segments is surrounded by a cladding, and the optical loss is reduced by expanding the effective cross-sectional area of the core.

[0004] Non-Patent Document 1 discloses an optical fiber cable in which the side pressure applied to an optical fiber is controlled by controlling the number of core wires per unit cross-sectional area (core wire mounting density) of the optical fiber cable, and the optical loss in the optical fiber is suppressed.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Non-Patent Documents

[0006]

Non-Patent Document 1

[0007] According to the optical fiber cable described in Non-Patent Literature 1, the lateral pressure applied to the optical fiber is reduced, resulting in a smaller frictional force, which is the product of the lateral pressure and the coefficient of friction. Consequently, differences in the coefficient of linear expansion between components caused by cooling of the outer sheath after manufacturing or changes in ambient temperature after installation lead to differences in the actual expansion and contraction rates. This results in a problem where the optical fiber may protrude or retract relative to the surrounding components within the optical fiber cable. If the optical fiber protrudes, it may bend upon contact with the component it protrudes into, potentially causing optical loss. If it retracts, it may make connection and other operations difficult.

[0008] This disclosure has been made in view of the above-mentioned problems. Its purpose is to provide an optical fiber cable that can suppress the protrusion or retraction of an optical fiber relative to a peripheral component of the optical fiber within the optical fiber cable. [Means for solving the problem]

[0009] To solve the above-mentioned problems, an optical fiber cable according to one aspect of the present disclosure comprises an optical fiber tape formed by intermittently bonding at least two or more optical fiber cores with adhesive portions aligned in the longitudinal direction of the optical fiber cores, and a covering portion that covers the optical fiber tape and has protrusions on its inner wall. The protrusions abut the adhesive portions and prevent movement along the longitudinal direction of the optical fiber tape. [Effects of the Invention]

[0010] According to this disclosure, it is possible to suppress the protrusion or retraction of the optical fiber relative to the surrounding components within the optical fiber cable. [Brief explanation of the drawing]

[0011] [Figure 1] Figure 1 is a cross-sectional view showing the configuration of an optical fiber cable according to an embodiment of this disclosure. [Figure 2] Figure 2 is a top view showing the configuration of an optical fiber tape. [Figure 3] Figure 3 is a side perspective view showing the configuration of the optical fiber tape and its covering. [Figure 4] Figure 4 is a cross-sectional view showing the configuration of the optical fiber tape and its covering. [Figure 5] Figure 5 is a side perspective view showing the configuration of the optical fiber tape and the covering portion according to the first modified example. [Figure 6] Figure 6 is a schematic diagram of the main components showing the configuration of the optical fiber tape and the covering part according to the first modified example. [Figure 7] Figure 7 is a side perspective view showing the configuration of the optical fiber tape and the covering portion according to the second modified example. [Modes for carrying out the invention]

[0012] Next, embodiments of the present disclosure will be described in detail with reference to the drawings. In the description, identical components are denoted by the same reference numerals, and redundant explanations will be omitted.

[0013] [Description of Embodiments] Figure 1 is a cross-sectional view showing the configuration of an optical fiber cable according to an embodiment of this disclosure. The optical fiber cable comprises an optical fiber core 10, a retaining winding 30, and an outer sheath 40. As will be described later, at least two or more optical fiber cores 10 are bonded to each other to form an optical fiber tape 20. Note that the cable structure of the optical fiber cable is not limited to a small diameter high density structure, and may be a slot structure or a loose tube structure.

[0014] The press winding 30 and the outer covering 40 constitute the covering portion 50. The press winding 30 covers the optical fiber tape 20, and further, the outer covering 40 covers the optical fiber tape 20 and the press winding 30. Note that the covering portion 50 may be constituted only by the press winding 30 or only by the outer covering 40. In the following description, the covering portion 50 will be described as including the press winding 30.

[0015] FIG. 2 is a top view showing the configuration of the optical fiber tape. At least two or more optical fiber cores 10 are intermittently adhered by the adhesion portions 15 arranged in the longitudinal direction of the optical fiber cores 10 to constitute the optical fiber tape 20. In FIG. 2, the state where two optical fiber cores 10 are adhered to each other is shown, but it is not limited thereto. For example, three or more optical fiber cores 10 may be adhered via the adhesion portion 15.

[0016] FIG. 3 is a side perspective view showing the configuration of the optical fiber tape and the covering portion. In FIG. 3, a side surface along the longitudinal direction of the optical fiber cores 10 constituting the optical fiber tape 20 is shown. Further, the adhesion portions 15 that penetrate the optical fiber cores 10 and adhere the optical fiber cores 10 to each other are shown.

[0017] The press winding 30 (covering portion 50) has a protrusion 32 on the inner wall. Here, the "inner wall" is the surface of the press winding 30 on the side facing the optical fiber tape 20 when the covering portion 50 covers the optical fiber tape 20. Note that when the covering portion 50 is constituted only by the outer covering 40, the outer covering 40 has the protrusion 32 on the inner wall.

[0018] By providing the protrusion 32 on the inner wall of the covering portion 50, when the covering portion 50 covers the optical fiber tape 20, the protrusion 32 abuts on the adhesion portion 15 and prevents the movement of the optical fiber tape 20 along the longitudinal direction of the optical fiber core 10 (or the optical fiber tape 20). The movement of the optical fiber core 10 is suppressed by the locking force generated when the protrusion 32 catches on the adhesion portion 15.

[0019] The projection 32 may be made of a flexible material that is elastically deformable upon contact with the optical fiber core 10. Elastic deformation upon contact with the optical fiber core 10 helps to suppress an increase in optical loss in the optical fiber core 10.

[0020] Alternatively, the projection 32 may be formed by pressing a jig against the retaining wrap 30 or the outer cover 40. The projection 32 may also be formed by embedding a projection into the surface of the retaining wrap 30 or the outer cover 40. In addition, when forming the retaining wrap 30 or the outer cover 40 by extrusion molding of resin or the like, the projection 32 may be formed on the retaining wrap 30 or the outer cover 40 by a shutter structure that opens and closes at predetermined intervals.

[0021] In addition, the retaining wrap 30 may be made of a strip-shaped material such as cloth or film, or a string-shaped material. Furthermore, one retaining wrap 30 may cover all the optical fiber cores 10 included in the optical fiber cable together, or multiple retaining wraps 30 may be used to cover them in sections. Since the outer surface of the retaining wrap 30 does not come into contact with the optical fiber cores 10, the condition of the outer surface can be set arbitrarily. For example, by increasing the adhesion of the surface, slippage between the retaining wrap 30 and the outer sheath 40 can be suppressed.

[0022] The advantages of separating the retaining wrap 30 from the outer sheath 40 can be explained as follows. First, the outer sheath 40 is a component that protects the optical fiber cable from external forces such as being stepped on. If a projection 32 is provided on the inner surface of the outer sheath 40, the outer sheath 40 must be designed considering both protection against external forces and ensuring the locking force at the projection 32. Therefore, there is a problem that the degree of freedom in material selection and structure of the outer sheath 40 is reduced.

[0023] In contrast, by separating the retaining wrap 30 from the outer cover 40 and providing a projection 32 on the retaining wrap 30, it becomes possible to independently design for protection against external forces and for ensuring the locking force at the projection 32. As a result, ensuring the locking force at the projection 32 becomes easier.

[0024] In addition, the projection 32 may be any member located on the outer circumference of the optical fiber core 10, and the projection 32 may be provided on a member other than the retaining winding 30 or the outer sheath 40.

[0025] As shown in Figure 3, the projections 32 may be provided at intervals Ps in the longitudinal direction, and the adhesive portions 15 may be provided at intervals Pa in the longitudinal direction. If the adhesive portions 15 have a length La in the longitudinal direction, the intervals Ps of the projections 32 in the longitudinal direction may be smaller than the length obtained by subtracting the length La of the adhesive portions 15 from the intervals Pa of the adhesive portions 15.

[0026] This ensures that the projection 32 can fit into the gap between the adhesive portion 15 and the projection 32, regardless of their relative positions. As a result, the locking force generated by the projection 32 catching on the adhesive portion 15 can be improved. Therefore, the effect of suppressing the movement of the optical fiber core 10 is increased.

[0027] Next, Figure 4 is a cross-sectional view showing the configuration of the optical fiber tape and the covering. In Figure 4, a cross-section of the optical fiber tape 20 in a plane perpendicular to the central axis of the optical fiber core 10 is shown. Here, the height Hs of the projection 32 shown in Figure 4 may be greater than half the outer diameter Df of the optical fiber core 10.

[0028] Due to variations during manufacturing, the thickness of the adhesive portion 15 may vary. However, since the height Hs is greater than half of the outer diameter Df, it is guaranteed that the projection 32 will engage with the adhesive portion 15. Therefore, regardless of variations during manufacturing of the adhesive portion 15, a locking force can be obtained by the projection 32 catching on the adhesive portion 15. Thus, the effect of suppressing the movement of the optical fiber core 10 is increased.

[0029] [Explanation of the first variation] Next, a first modified example will be described. Figure 5 is a side perspective view showing the configuration of the optical fiber tape and the covering part according to the first modified example. Figure 6 is a schematic diagram of the main parts showing the configuration of the optical fiber tape and the covering part according to the first modified example. In particular, Figure 6 shows the positional relationship when the projection 33 in Figure 5 is engaged with the adhesive part 15.

[0030] The retaining wrap 30 (covering portion 50) has a projection 33 on its inner wall. Unlike the projection 32 shown in Figure 3, the projection 33 shown in Figures 5 and 6 has a tip that is bent toward the inner wall. For example, the tip of the projection 33 is bent in a claw shape (hook shape). Note that the bending direction of the tip of the projection 33 does not need to be parallel to the longitudinal direction.

[0031] The bending of the tip of the projection 33 in this manner makes it easier for the projection 33 to engage with the adhesive portion 15. As a result, the locking force generated by the projection 33 catching on the adhesive portion 15 can be improved. Therefore, the effect of suppressing the movement of the optical fiber core 10 is increased.

[0032] Furthermore, if the tip of the projection 33 comes into direct contact with the optical fiber core 10, the bending applied to the projection 33 will progress, causing the projection 33 to deform further. This elastic deformation due to contact with the optical fiber core 10 reduces the lateral pressure applied to the optical fiber. Therefore, an increase in optical loss in the optical fiber core 10 is suppressed.

[0033] In Figure 6, the distance from the inner wall to the point on the side of the tip of the projection 33 that is furthest from the inner wall is shown as distance Hsh. Distance Hsh may be greater than half the outer diameter Df of the optical fiber core 10.

[0034] Due to variations during manufacturing, the thickness of the adhesive portion 15 may vary. However, since the distance Hsh is greater than half of the outer diameter Df, it is guaranteed that the projection 33 will engage with the adhesive portion 15. Therefore, regardless of variations during manufacturing of the adhesive portion 15, a locking force can be obtained by the projection 33 catching on the adhesive portion 15. Thus, the effect of suppressing the movement of the optical fiber core 10 is increased.

[0035] [Explanation of the second variation] Next, a second modified example will be described. Figure 7 is a side perspective view showing the configuration of the optical fiber tape and the covering part according to the second modified example.

[0036] The retaining wrap 30 (covering portion 50) is provided with projections 33 and 34 on its inner wall. Here, the bending direction of the tip of projection 34 is different from the bending direction of the tip of projection 33. Note that the bending direction of the tip of projection 33 and the bending direction of the tip of projection 34 do not need to be parallel to the longitudinal direction. Also, the bending direction of the tip of projection 33 and the bending direction of the tip of projection 34 do not need to be antiparallel.

[0037] As a result, movement in both directions along the longitudinal direction of the optical fiber tape 20 is prevented by the protrusions 33 and 34. Therefore, the effect of suppressing the movement of the optical fiber core 10 is increased.

[0038] [Effects of the Embodiment] As described in detail above, the optical fiber cable according to this embodiment comprises an optical fiber tape formed by intermittently bonding at least two or more optical fiber cores with adhesive portions aligned in the longitudinal direction of the optical fiber cores, and a covering portion that covers the optical fiber tape and has protrusions on its inner wall. This makes it possible to suppress the protrusion or retraction of the optical fiber relative to the surrounding members of the optical fiber within the optical fiber cable.

[0039] The projection is provided on the inner wall of the covering portion, so that the projection comes into contact with the adhesive portion and prevents the optical fiber tape (or optical fiber tape) from moving along the longitudinal direction of the optical fiber core. The locking force generated when the projection catches on the adhesive portion suppresses the movement of the optical fiber core.

[0040] Furthermore, in the optical fiber cable according to this embodiment, the interval between the protrusions in the longitudinal direction may be smaller than the length obtained by subtracting the length of the adhesive portion from the interval between the adhesive portions. This ensures that the protrusions fit into the gap between the adhesive portions, regardless of the positional relationship between the adhesive portions and the protrusions. As a result, the locking force generated by the protrusions catching on the adhesive portions can be improved. Therefore, the effect of suppressing the movement of the optical fiber core is increased.

[0041] Furthermore, in the optical fiber cable according to this embodiment, the height of the projection may be greater than half the outer diameter of the optical fiber core. This ensures that the projection will engage with the adhesive even if the thickness of the adhesive part changes due to variations during manufacturing. Therefore, regardless of variations during manufacturing of the adhesive part, a locking force can be obtained by the projection catching on the adhesive part. Thus, the effect of suppressing the movement of the optical fiber core is increased.

[0042] Furthermore, in the optical fiber cable according to this embodiment, the tip of the projection may be bent toward the inner wall along the longitudinal direction. This makes it easier for the projection to engage with the adhesive portion. As a result, the locking force generated by the projection catching on the adhesive portion can be improved. Therefore, the effect of suppressing the movement of the optical fiber core is increased.

[0043] Furthermore, if the tip of the protrusion comes into direct contact with the optical fiber core, the bending applied to the protrusion will progress, causing it to deform further. As a result, the lateral pressure applied to the optical fiber is reduced. Therefore, an increase in optical loss in the optical fiber core is suppressed.

[0044] Furthermore, in the optical fiber cable according to this embodiment, the distance from the inner wall to the point furthest from the inner wall among the side surfaces facing the inner wall at the tip may be greater than half the outer diameter of the optical fiber core. This ensures that the projection will engage with the adhesive even if the thickness of the adhesive part changes due to manufacturing variations. Therefore, regardless of manufacturing variations in the adhesive part, a locking force can be obtained by the projection catching on the adhesive part. Thus, the effect of suppressing the movement of the optical fiber core is increased.

[0045] Furthermore, in the optical fiber cable according to this embodiment, the sheathing portion may be provided with two or more protrusions, and the bending direction of the tip of one protrusion may be different from the bending direction of the tips of the other protrusions. As a result, movement in both directions along the longitudinal direction of the optical fiber tape is prevented by the two or more protrusions. Therefore, the effect of suppressing the movement of the optical fiber core is increased.

[0046] Furthermore, in the optical fiber cable according to this embodiment, the covering portion may be an outer sheath or a retaining winding. In particular, when the retaining winding and the outer sheath are separate, by providing a projection on the retaining winding, it is possible to independently design for protection against external forces and for ensuring locking force at the projection. As a result, it is possible to protect the optical fiber cable from external forces such as being stepped on while ensuring locking force at the projection.

[0047] Furthermore, in the optical fiber cable according to this embodiment, the protrusions may abut against the adhesive portion to prevent the movement of the optical fiber tape along the longitudinal direction. This makes it possible to suppress the optical fiber from protruding or receding relative to the surrounding members within the optical fiber cable.

[0048] While the contents of this disclosure have been described above in accordance with the embodiments, it will be obvious to those skilled in the art that this disclosure is not limited to these descriptions and that various modifications and improvements are possible. The discussions and drawings that constitute part of this disclosure should not be understood as limiting this disclosure. Various alternative embodiments, examples and operational techniques will become apparent to those skilled in the art from this disclosure.

[0049] This disclosure naturally includes various embodiments and other features not described herein. Therefore, the technical scope of this disclosure is determined solely by the inventive features relating to the claims that are reasonable given the above description. [Explanation of Symbols]

[0050] 10 Optical fiber core 15 Adhesive part 20 Fiber Optic Tapes 30 Pressing and wrapping 32,33,34 Protrusion 40 Outer cover 50 Covering part

Claims

1. An optical fiber tape is constructed by intermittently bonding at least two or more optical fiber cores using adhesive portions aligned in the longitudinal direction of the optical fiber cores, A covering portion that covers the optical fiber tape and has protrusions on its inner wall, Equipped with, The projection abuts against the adhesive portion and prevents the optical fiber tape from moving along the longitudinal direction. In the longitudinal direction, the interval between the protrusions is smaller than the length obtained by subtracting the length of the adhesive portion from the interval between the adhesive portions. Fiber optic cable.

2. The optical fiber cable according to claim 1, wherein the height of the projection is greater than half the outer diameter of the optical fiber core.

3. The optical fiber cable according to claim 1, wherein the tip of the projection is bent toward the inner wall along the longitudinal direction.

4. The optical fiber cable according to claim 3, wherein the distance from the inner wall to the side surface at the tip that faces the inner wall and is furthest from the inner wall is greater than half the outer diameter of the optical fiber core.

5. The covering portion comprises two or more of the aforementioned protrusions, The optical fiber cable according to claim 4, wherein the bending direction of the tip of one of the aforementioned projections is different from the bending direction of the tip of the other aforementioned projections.

6. The optical fiber cable according to any one of claims 1 to 5, wherein the covering portion is an outer sheath or a retaining winding.

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