JP4922280B2 - Fiber optic cable - Google Patents

Description

  The present invention performs optical communication by drawing and laying an optical fiber composed of one or more optical fiber strands, an optical fiber core wire, or an optical fiber tape core wire into a structure such as a small-scale building or a general household. The present invention relates to an optical fiber cable such as an optical fiber indoor cable or an optical fiber drop cable installed between utility poles when drawn into a small building or a general home.

  Conventionally, FTTH (Fiber to the Home), that is, home or office, can be used to transmit and receive high-speed broadband information such as ultra-high-speed data, from an access optical fiber cable extended from a telephone station, to a building or general home. An optical fiber made of an optical fiber strand, an optical fiber core wire, or an optical fiber tape core wire is drawn down to a subscriber's home, and a drop optical fiber cable is used for wiring the optical fiber. An optical fiber indoor cable is an optical fiber cable used when an optical fiber is drawn into each room in a home or office building. An optical fiber drop cable is used when an optical fiber is drawn into a home from a branch closure of a main line cable on a utility pole.

  The jacket of the optical fiber cable including the optical fiber indoor cable is made of a material having excellent performance in mechanical strength and heat resistance, but an unintentional impact force is applied from the outside during or after the wiring work. In some cases, the cable jacket may be damaged or cracked. As a result, the airtightness and waterproofness are lowered, and the insulation of the jacket is lowered, which adversely affects the optical fiber, such as impairing transmission loss.

  Therefore, in Patent Document 1, a cylindrical covering material excellent in impact resistance and the like for a round cable is proposed. In other words, the cylindrical covering material is attached to a long article such as a cable and covers the surface thereof, and is made of a polymer material having viscoelasticity. The protrusions are arranged in the longitudinal direction. The plurality of hook-shaped protrusions have, for example, a gear-shaped cross-sectional structure.

  Patent Document 2 discloses an optical fiber indoor cable having a structure that does not reduce impact resistance. For example, as shown in FIG. 6, the optical fiber indoor cable 101 includes an optical fiber 103 made of an optical fiber strand, an optical fiber core wire, or an optical fiber tape core wire disposed in the center, and the optical fiber 103. Of the X-axis 113 passing through the center of the optical fiber 103 in the X-axis direction which is one of the two directions orthogonal to the longitudinal direction (the direction orthogonal to the paper surface in FIG. 6) (the left-right direction in FIG. 6). A pair of strength members 105 arranged in parallel on both sides, and a jacket 107 made of resin having a rectangular cross-sectional shape integrally covering the outer periphery of the optical fiber 103 and the pair of strength members 105 An optical element portion 109 of a scale is configured.

  Furthermore, a notch 111 is formed on the surface of the outer jacket 107. The notch 111 is a straight line that is perpendicular to the X axis 113 of the optical fiber 103 and the pair of strength members 105 and is parallel to the Y axis 115 (vertical direction in FIG. 5) passing through the center of the optical fiber 103. Thus, the optical fiber 103 is formed on the surface of the jacket 107 near the vertical planes (BB) and (CC) located on both sides in the X-axis direction.

In addition, the optical fiber indoor cable of Patent Document 3 will be described in comparison with the optical fiber indoor cable 101 of FIG. 5. At least one or more convex portions for absorbing side pressure are formed on the surface on both sides in the Y-axis direction of the jacket 107.
JP 2003-61222 A JP 2004-206008 A JP 2005-215051 A

  By the way, when the optical fiber 103 is wired to each room in an existing apartment by the optical fiber indoor cable 101, the wiring space is narrow. Therefore, in recent years, an optical fiber indoor cable having a smaller diameter than the indoor cable used so far has been studied.

  However, since the cylindrical covering material of Patent Document 1 is attached to a long article such as a cable and covers the surface thereof to impart impact resistance, it is difficult to reduce the size of the optical fiber cable. There was a problem.

  Moreover, in patent document 2 and patent document 3, when an optical fiber cable is reduced in diameter, degradation of impact resistance, etc. are assumed. For example, when the optical fiber indoor cable 101 having a diameter of 1.5 mm or more and 1.6 mm or less is produced by reducing the diameter of the element portion 109, after the impact test in accordance with IEC60794-1-2 The following results are produced.

  That is, in Patent Document 2, when the diameter of the cable is reduced, the appearance of the cable is expected to cause the exposure of the tensile body 105, and there is a problem that it becomes a defective product. That is, since the notch 111 is displaced in the left-right direction in FIG. 6 with respect to the optical fiber 103, the upper notch 111 is easily broken and the tensile body 105 is easily exposed. Further, the cable transmission loss residual value has a problem that a fluctuation in loss of 0.1 dB or more is expected, resulting in a defective product. That is, since the notch 111 is displaced in the left-right direction in FIG. 6 with respect to the optical fiber 103, an impact force is transmitted to the optical fiber 103 from above and below.

  In Patent Document 3, when the cable is reduced in diameter, the appearance of the cable is expected to expose the tensile body 105 when the width of the side pressure absorbing convex portion is 30% or less of the upper and lower sides. In other words, if the width of the side pressure absorbing convex portion is small, the impact cannot be completely received, and cracks run above and below the tensile body 105, causing the tensile body 105 to be exposed. Further, the cable transmission loss residual value is expected to have a loss fluctuation of 0.1 dB or more when the width of the side pressure absorbing convex portion is 70% or more of the upper and lower sides. That is, there is a problem that if the width of the side pressure absorbing convex portion is large, an impact force is transmitted to the optical fiber 103 and transmission loss increases.

  An object of the present invention is to prevent transmission loss from being deteriorated due to local impact force concentration and cracking of the jacket even when the outer diameter of the cable is reduced to reduce the thickness of the jacket.

In order to solve the above problems, an optical fiber cable according to the present invention includes one or more optical fiber strands or optical fiber core wires or optical fiber tape core wires disposed in the center, and the optical fiber. A pair of tensile strengths arranged parallel to one of the two directions perpendicular to the longitudinal direction of the optical fiber and extending in the longitudinal direction of the optical fiber on both sides of the optical fiber on a straight line passing through the center of the optical fiber An optical fiber cable that forms a long optical element portion from a body and a jacket that integrally covers the outer periphery of the optical fiber and a pair of strength members, and is orthogonal to the longitudinal direction of the optical fiber. when subjected to an external force from the other direction among the directions, in order to distort the minor diameter of the one direction at both ends in the said outer concave, both surfaces of said other direction side in the said outer , Before Symbol a position closer to the optical fiber diameter as base between one direction of the envelope ends with formed in a recess of a triangle whose vertices, all corners of the envelope is formed at an acute angle it is characterized in that there.

  Moreover, the optical fiber cable of this invention WHEREIN: It is preferable that the notch part is formed in the vertex of the position near the said optical fiber of the surface of the said recessed part in the said optical fiber cable.

In the optical fiber cable of the present invention, in the optical fiber cable, the minor axis between both ends of the outer jacket in the other direction perpendicular to the one direction in the cross section in the other direction perpendicular to the one direction is 1.0 mm or more. And the bending elastic modulus of the jacket is 60 MPa or more and 1000 MPa or less, the depth to the apex of the triangular recess is 10% or more of the minor axis of the jacket, and 30 % Or less is preferable.

  Moreover, the optical fiber cable of this invention WHEREIN: It is preferable that the depth of the said notch part is 0.1 mm or more and 0.4 mm or less in the said optical fiber cable.

  In the optical fiber cable of the present invention, in the optical fiber cable, it is preferable that a long cable support line portion in which a support wire is covered with an outer sheath is integrated with the optical element portion in parallel with each other.

  As can be understood from the means for solving the problems as described above, according to the present invention, since the triangular concave portion is formed on the surface of the jacket substantially parallel to one direction, the cable outer diameter is reduced. Even if the thickness of the jacket is reduced, it is possible to prevent degradation of transmission loss and cracking of the jacket due to local impact force concentration. Therefore, even if an inadvertent impact is applied to the optical fiber cable during wiring work or after wiring to an existing apartment or the like, wiring can be easily performed without impairing transmission loss. Therefore, if a triangular recess is formed on the surface of the jacket that is almost parallel to one direction, it has excellent impact resistance and mechanical properties, so the cable can be made thinner and lighter, and wiring space can be saved. And labor saving.

  Embodiments of the present invention will be described below with reference to the drawings.

  Referring to FIG. 1, for example, an optical fiber indoor cable 1 as an optical fiber cable according to this embodiment includes one or more optical fiber strands or optical fiber core wires or optical fibers arranged at the center. An optical fiber 3 made of a fiber ribbon and one of two directions orthogonal to the longitudinal direction of the optical fiber 3 (the direction orthogonal to the paper surface in FIG. 1) (the horizontal direction in FIG. 1, the X-axis direction) ) And a pair of strength members 5 extending in the longitudinal direction of the optical fiber 3 on both sides of the optical fiber 3 on a straight line (X axis) passing through the center of the optical fiber 3, and the light A long optical element portion 9 is constituted by a jacket 7 made of a resin that integrally covers the outer periphery of the fiber 3 and the pair of strength members 5.

  Further, the surface of the jacket 7 that is substantially parallel to the X-axis 11 passing through the centers of the optical fiber 3 and the pair of strength members 5 is between the ends of the jacket 7 in the X-axis direction in a cross section perpendicular to the X-axis 11. A triangular recess 13 is formed with the long axis A of the base as the base and the apex C at a position close to the optical fiber 3.

  In addition, in the cross section perpendicular to the X axis 11, the concave portion of the jacket 7 on both sides of the optical fiber 3 in the Y axis direction orthogonal to the X axis 11 (the other direction out of the two directions orthogonal to the optical fiber 3). On the surface of 13, a notch portion 15 is formed at a vertex C at a position close to the optical fiber 3. In this embodiment, as shown in FIG. 1, the two notches 15 are located on the Y axis.

  In the optical element section 9 described above, the minor axis B between both ends of the outer jacket 7 in the Y-axis direction orthogonal to the X-axis in a cross section perpendicular to the X-axis 11 is 1.0 mm or more, and 2. It is desirable that it is 0 mm or less. The reason is that when the minor axis B is smaller than 1.0 mm, it is difficult to ensure desired impact resistance. On the other hand, when the minor axis B is larger than 2.0 mm, the diameter is not reduced.

  The elastic modulus of the material of the outer jacket 7 is desirably 60 MPa or more and 1000 MPa or less. The reason for this is that when the elastic modulus is smaller than 60 MPa, the cushioning property is large and the pressure resistance is lowered, so that the influence of an external force applied to the optical fiber 3 cannot be prevented. On the other hand, when the elastic modulus is larger than 1000 MPa, the cushioning property is lowered, so that it is difficult to absorb the impact force, so that it is difficult to ensure desired impact resistance.

  Further, it is desirable that the depth D to the vertex C of the triangular concave portion 13 is 10% or more and 30% or less of the minor axis B of the outer cover 7. The reason for this is that when the depth D to the apex C of the recess 13 is smaller than 10% of the minor axis B of the outer jacket 7, the distance to absorb the impact force is shortened, so that the desired impact resistance is ensured. It is difficult. On the other hand, when the depth D to the apex C of the recess 13 is larger than 30% of the short diameter B of the jacket 7, the thickness of the jacket 7 with respect to the optical fiber 3 is reduced. The strength of 7 decreases.

  The depth of the notch 15 is preferably 0.1 mm or more and 0.4 mm or less. The reason for this is that when the depth of the notch portion 15 is smaller than 0.1 mm, the tearability of the outer jacket 7 is lowered, so that the lead-out property of the optical fiber 3 is lowered. On the other hand, when the depth of the notch portion 15 is larger than 0.4 mm, the thickness of the outer cover 7 with respect to the optical fiber 3 is reduced, so that the strength of the outer cover 7 protecting the optical fiber 3 is lowered.

  Although FIG. 1 shows a case in which the notch portion 15 is formed in the outer jacket 7, the outer jacket 7 having only the recess 13 may be provided without the notch portion 15. In this case, a notch tool such as a detacher (not shown) can be used to make a cut from the apex C of the recess 13 for tearing.

  Next, in order to examine the effect of the optical fiber indoor cable 1 of the above-described embodiment, an example based on the configuration of this embodiment is created, and the light of the comparative example is compared with this example. A fiber indoor cable 17 was prepared. In the embodiment, as shown in FIG. 3, the triangular recesses 13 are provided on the upper and lower surfaces of the outer cover 7. In the comparative example, as shown in FIG. 4, a notch portion 15 is provided at the position of the Y axis passing through the center of the optical fiber 3 on the upper and lower surfaces of the outer cover 7 having a rectangular cross section.

A pressure of 0.5 kg / mm ² was applied to the optical fiber indoor cables 1 and 17 of the example and the comparative example by a method of mechanically applying an impact force as shown in FIG. As shown in FIGS. 3 and 4, the result is expressed as a stress distribution generated in the cable, and is shown in five stages from a low stress level (I) to a high level (V).

  As shown in FIG. 3, the stress distribution in the optical fiber indoor cable 1 of the embodiment is such that the corners of the minor axis B on both ends in the X-axis direction of the outer jacket 7 are stress levels (III) to ( IV), and the vicinity of the strength member 5 is about the stress level (II). Further, the vicinity of the optical fiber 3 is about the stress level (I) to (II), and the periphery of the optical fiber 3 is almost about the stress level (I).

  On the other hand, as shown in FIG. 4, the stress distribution in the optical fiber indoor cable 17 of the comparative example has a stress level (II) in the upper and lower portions of the tensile strength body 5 in the upper and lower belt-shaped ranges. The portion of the minor axis B on both ends in the X-axis direction and the periphery of the optical fiber 3 as a whole have a stress level (V), and the vicinity of the left and right sides of the strength member 5 is the stress level (V). Furthermore, stress levels (II), (IV), and (V) are mixed near the center of the optical fiber 3.

  From the above, the optical fiber indoor cable 1 according to the embodiment is provided with the triangular recess 13 on the surface of the outer cover 7 substantially parallel to the X axis 11, so that the impact force as shown in FIG. It is understood that the amount of shock transmitted to the optical fiber 3 is reduced by distorting the portion of the minor axis B on both end sides in the X-axis direction of the outer cover 7. On the other hand, since the optical fiber indoor cable 17 of the comparative example cannot absorb the impact force, a high level of stress is generated in the entire outer jacket 7. Therefore, it can be seen that the impact on the optical fiber 3 cannot be reduced.

  Therefore, the optical fiber indoor cable 1 of this embodiment absorbs the impact force to reduce the impact on the optical fiber 3, and reduces the stress applied to the upper and lower portions of the strength member 5 in FIG. Therefore, the tensile strength body 5 can be prevented from being exposed to the surface of the outer cover 7 after receiving an impact force.

  As a result, even if the outer diameter of the cable is reduced and the thickness of the outer cover 7 is reduced, it is possible to prevent the transmission loss from being deteriorated due to local impact force concentration and the occurrence of cracks in the outer cover 7. Even if an inadvertent impact is applied to the optical fiber indoor cable 1 when wiring to an existing apartment or the like, wiring can be easily performed without impairing transmission loss.

  In addition, the optical fiber indoor cable 1 of this embodiment has much better appearance and residual transmission loss than the cases of Patent Document 2 and Patent Document 3 described above.

  In addition, although the optical fiber cable of embodiment mentioned above demonstrated the optical fiber indoor cable 1, it is applicable also to the optical fiber drop cable 19 as FIG. 5 shows.

  That is, the optical fiber drop cable 19 is, for example, suspended as a support line via the elongated optical element portion 9 in the above-described optical fiber indoor cable 1 and the neck portion 21 on the left side of the outer cover 7 in the optical element portion 9. And a long cable support line portion 27 integrated with an outer sheath 25 made of a resin covering the wire 23. Moreover, the central axis of the suspension line 23 coincides with the X axis 11. The jacket 7 of the optical element section 9 and the jacket 25 of the cable support line section 27 may be made of the same resin. Further, since the basic operation and effect of the optical fiber drop cable 19 are almost the same as those of the optical fiber indoor cable 1 described above, detailed description is omitted.

It is a longitudinal cross-sectional view of the optical fiber indoor cable as an optical fiber cable of this embodiment. It is sectional drawing which shows a state when an impact force is applied to the optical fiber cable of FIG. FIG. 2 is a stress distribution diagram when an impact force is applied to the optical fiber cable of FIG. 1. It is a stress distribution map when an impact force is applied to the optical fiber cable of the comparative example. It is a longitudinal cross-sectional view of the optical fiber drop cable as an optical fiber cable of this embodiment. It is a longitudinal cross-sectional view of the conventional optical fiber indoor cable.

Explanation of symbols

1 Optical fiber indoor cable (fiber optic cable, in the example)
3 Optical fiber 5 Strength member 7 Jacket 9 Optical element part 11 X-axis plane 13 Recess 15 Notch part 17 Optical fiber indoor cable (for comparative example)
19 Optical fiber drop cable (optical fiber cable)
21 Neck part 23 Suspension line (support line)
25 Outer jacket 27 Cable support line

Claims (5)

An optical fiber composed of one or more optical fiber strands or optical fiber core wires or optical fiber tape core wires disposed in the center;
The optical fiber is arranged to extend in the longitudinal direction of the optical fiber on both sides of the optical fiber on a straight line parallel to one of the two directions orthogonal to the longitudinal direction of the optical fiber and passing through the center of the optical fiber. A pair of strength members,
A jacket that integrally covers the outer periphery of the optical fiber and a pair of strength members;
From the optical fiber cable constituting the long optical element part,
When an external force is applied from the other direction out of the two directions orthogonal to the longitudinal direction of the optical fiber, in order to distort the minor axis on both ends of the one direction in the outer cover into a concave shape,
Both surfaces of the side of the other direction of the outside of the can, together with the formed a position closer to the optical fiber diameter between before SL direction of the envelope across the bottom in the concave portion of the triangle whose vertices, the An optical fiber cable characterized in that all corners of the jacket are formed with acute angles .   The optical fiber cable according to claim 1, wherein a notch portion is formed at a vertex of the surface of the concave portion near the optical fiber. The minor axis between both ends of the outer jacket in the other direction perpendicular to the one direction is 1.0 mm or more and 2.0 mm or less, and the bending elastic modulus of the jacket is 60 MPa or more and 1000 MPa or less, 3. The optical fiber cable according to claim 1, wherein the depth to the apex of the triangular recess is 10% or more and 30% or less of the minor axis of the jacket.   The optical fiber cable according to claim 2 or 3, wherein a depth of the notch is 0.1 mm or more and 0.4 mm or less.   5. The optical fiber cable according to claim 1, wherein a long cable support line part in which a support line is covered with a jacket is integrated in parallel with the optical element part.

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