JP2009063796A - Optical fiber cable - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical fiber cable in which the workability of taking out a coated optical fiber from a sheath is improved even when flat tension bodies are used. <P>SOLUTION: The sectional form of the tension bodies 12 and 13 is flat so that the short side comes in the direction perpendicular to a first straight line P1 which connects the coated optical fiber 11 and the center of the tension bodies 12 and 13. The sheath 20 has: a first notch 31 formed on one of the surfaces while interposing the first straight line P1 for taking out the coated optical fiber 11; and a second notch 32 formed on the other surface part for taking out the coated optical fiber, wherein the angle θ between the first straight line P1 and a second straight line P2 which connects the end part of the first notch of the sheath and the end part of the second notch is 70 degrees or smaller. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an optical fiber cable, and more particularly, to an optical fiber cable used for taking an optical fiber into a home, and an optical fiber cable used for routing an optical fiber in a home or campus.

In recent years, construction of a line network for optical communication subscribers has been progressing. Examples of the optical fiber cable include a drop optical fiber cable for pulling in from the trunk optical fiber cable into a home such as each home, and an indoor optical fiber cable used for routing in the home or on the ground such as each home. As a cross-sectional shape of a conventional tensile member (tension member) of an optical fiber cable, a circular shape is generally used, but a flat shape (rectangular shape) may be used. (For example, see Patent Document 1 and Patent Document 2).
JP 2005-49505 A JP 2005-49658 A

  However, in Patent Document 1 and Patent Document 2, when a tensile body 101 having a circular cross section is used as in the optical fiber cable 100 shown in FIG. 6, the sheath 102 of the optical fiber cable 100 is notched. When the sheath 102 is divided from the (cut portion) 103 as a starting point, a sheath dividing surface 105 is formed in a direction perpendicular to the direction S in which the two sheath pieces 102C and 102D are separated from the optical fiber core wire 104. . For this reason, the optical fiber core wire 104 is not attached to any of the sheath pieces 102C and 102D when the sheath is divided, and the original position can be substantially maintained. Therefore, the optical fiber core wire 104 can be easily taken out.

  On the other hand, when the strength member 201 having a rectangular cross section is used as in the optical fiber cable 200 shown in FIG. 7, the optical fiber cable 200 is sheathed starting from the notch (cut portion) 203. When 202 is divided, the left and right sheath pieces 202C and 202D of the sheath 202 are divided along a direction T (parallel to the sheath dividing surface 205) in which the optical fiber cable 200 is sheared. 202, the optical fiber core wire 204 is difficult to take out from the sheath 202 and may stick to either of the sheath pieces 202C, 202D. is there.

  This is because when the optical fiber cable 100 using the strength member 101 having a circular cross section shown in FIG. 6 is divided, the strength member 101 is easily bent in any direction to the same extent. It is possible to tear the left and right sheath pieces 102C, 102D apart in the direction of tearing. In other words, since the sheath pieces 102C and 102D can be torn while the optical fiber core wire 104 is substantially maintained at the original position, the optical fiber core wire 104 can be easily taken out.

On the other hand, when the sheath 202 of the optical fiber cable 200 using the tensile body 201 having a rectangular cross section shown in FIG. 7 is divided, the tensile body 201 easily bends in the short side direction instead of the long side direction. The left and right sheath pieces 202C and 202D are split in a direction parallel to the surface 205. Therefore, since the direction S2 in which the optical fiber core 204 protrudes from the sheath pieces 202C and 202D is parallel to the sheath dividing surface 205, the optical fiber core 204 is in the optical fiber core receiving hole 206 of the sheath 202. It is considered that it is difficult to take out the optical fiber core wire 204 because it may be attached to either of the sheath pieces 202C and 202D.
Therefore, in order to solve the above-described problems, the present invention has an object to provide an optical fiber cable that can improve the workability of taking out an optical fiber core wire from a sheath even when a flat tensile body is used. And

In order to solve the above problems, an optical fiber cable of the present invention includes an optical fiber core wire,
At least a pair of strength members disposed on both sides of the optical fiber core in parallel with the optical fiber core;
In the optical fiber cable having a sheath that integrally covers the optical fiber core wire and the pair of strength members,
In the vertical cross section with respect to the longitudinal direction of the optical fiber cable, the center of the optical fiber core and the center of each of the pair of strength members are located on substantially the same straight line,
The cross-sectional shape of the pair of strength members is flat so that the short side comes in a direction substantially perpendicular to the first straight line connecting the optical fiber core and the center of the strength member,
The sheath has a first notch for taking out the optical fiber core formed on one surface portion across the first straight line, and an optical fiber core wire taken out on the other surface portion. A second notch,
The angle formed by the first straight line of the plurality of strength members and the second straight line connecting the distal end portion of the first notch and the distal end portion of the second notch of the sheath is 70 degrees or less. To do.

  According to the present invention, it is possible to improve the workability of taking out the optical fiber core wire from the sheath even when a flat tensile body is used.

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

<First Embodiment>
FIG. 1 is a cross-sectional view in a plane perpendicular to the longitudinal direction L showing a first preferred embodiment of the optical fiber cable of the present invention. FIG. 2 is a diagram showing a state when the sheath of the optical fiber cable shown in FIG. 1 is divided.
An optical fiber cable 10 according to an embodiment of the present invention shown in FIG. 1 is an indoor optical fiber cable that can be used in, for example, a home such as each household or a premises such as a factory.

An optical fiber cable 10 shown in FIG. 1 includes an optical fiber core 11 and a pair of strength members (also referred to as tension members) 12 and 13 disposed on both sides of the optical fiber core 11 in parallel with the optical fiber core 11. And a sheath (also referred to as a covering portion or a main body portion) 20 integrally covering the optical fiber core wire 11 and the two strength members 12 and 13.
The optical fiber core wire 11 is, for example, a silica-based optical fiber having a core, a cladding covering the periphery of the core, and a coating covering the periphery of the cladding. The diameter of the optical fiber core wire 11 is, for example, 0.25 mm.

In the cross section orthogonal to the longitudinal direction L of the optical fiber cable 10, the center 11 of the optical fiber core and the centers of the pair of strength members 12, 13 are located on substantially the same straight line. The cross-sectional shape of 13 is flat so that the short side comes in a direction substantially perpendicular to the first straight line P1 connecting the optical fiber core wire 11 and the centers of the strength members 12 and 13.
That is, the strength members 12 and 13 have a rectangular (rectangular) cross-sectional shape of the same size, and the short sides 14 of the strength members 12 and 13 are perpendicular to the first straight line P1, and the strength members The long sides 15 of 12 and 13 are parallel to the first straight line P1. The length D of the short side 14 of the strength members 12 and 13 × the length B of the long side 15 is, for example, 0.27 mm × 0.55 mm, and the strength members 12 and 13 are made of aramid-FRP (fiber reinforced plastic). I am using something.

On the other hand, in the cross section orthogonal to the longitudinal direction L of the optical fiber cable 10, the sheath 20 is substantially rectangular, and the four corner portions are quarter-circular round portions 39 each having the same radius. . The long side S is substantially parallel to the first straight line P1, and the short side R is substantially perpendicular to the first straight line P1.
Examples of the material of the sheath 20 shown in FIG. 1 include, but are not limited to, polyvinyl chloride, polyethylene, polyurethane, and the like. The length R in the short side direction of the sheath 20 is 2.0 mm, and the length S in the long side direction of the sheath 20 is 3.1 mm. In this type of optical fiber cable, the length R in the short side direction of the sheath 20 is usually 1.0 to 3.5 mm, and the length S in the long side direction of the sheath 20 is about 2.0 to 6.0 mm. .

  The sheath 20 has a first notch 31 and a second notch 32 across the first straight line P1. The first notch 31 is a cut portion formed on one long side 41 of the sheath 20, and the second notch 32 is a cut portion formed on the other long side 42 of the sheath 20.

  As shown in FIG. 1, the first notch 31 and the second notch 32 are grooves each having a substantially V-shaped cross section along the longitudinal direction L (the direction perpendicular to the paper in FIG. 1). The first notch 31 has a first straight portion 31B, a second straight portion 31C, and a first tip portion 31D, and the second notch 32 has a first straight portion 32B, a second straight portion 32C, and a second tip. It has a part 32D. The first straight portion 31B is longer than the second straight portion 31C, and the first straight portion 32B is longer than the second straight portion 32C.

The tip 31D of the first notch 31 and the tip 32D of the second notch 32 can be connected by a second straight line P2. The tip 31D and the tip 32D are also referred to as notch bottoms.
A first straight line P1 connecting the optical fiber core wire 11 and the centers of the two strength members 12 and 13, and a second straight line P2 connecting the distal end portion 31D of the first notch 31 and the distal end portion 32D of the second notch 32 of the sheath 20. Is an angle θ other than a right angle, and this angle θ is preferably 70 degrees or less. This angle θ is more preferably not less than 30 degrees and not more than 70 degrees. If the angle θ is smaller than 30 degrees, there is a risk that when the sheath 20 is divided, the crack does not face the optical fiber core wire 11 and runs to the strength members 12 and 13, which is not preferable. Also, if the angle θ exceeds 70 degrees, the take-out workability when taking out the optical fiber core from the sheath is reduced, and there is a probability that the optical fiber core 11 will be in one of the sheath pieces 20L, 20R. It becomes high and is not preferable.

Here, with reference to FIG. 2, taking out of the optical fiber core wire 11 when the sheath 20 is divided will be described.
When the operator divides the sheath 20 at the first notch 31 and the second notch 32 and tries to take out the optical fiber core wire 11 from the sheath 20, the two strength members 12 and 13 have the short sides 14. The right and left sheath pieces 20L and 20R are torn apart along the direction G parallel to the short side 14 of the strength members 12 and 13.
On the other hand, the sheath 20 is divided along a dividing surface 60 (corresponding to the second straight line P2) connecting the distal end portion 31D and the distal end portion 32D indicated by a broken line in FIG.
Therefore, since the split surface 60 of the sheath 20 is not horizontal with respect to the direction in which the optical fiber cable 10 bends, the left and right sheath pieces 20L and 20R are split at an angle with respect to the split surface 60 of the sheath 20. . In other words, since the direction H in which the optical fiber core wire 11 protrudes from the optical fiber core housing holes 65 and 65 of the sheath pieces 20L and 20R has an angle α with respect to the split surface 60 of the sheath 20, the optical fiber The core wire 11 can be easily taken out.

Next, Examples 1-4 of the optical fiber cable of the first embodiment of the present invention and Comparative Example 1 outside the scope of the present invention are evaluated with reference to FIG. An example of performing is described.
FIG. 3 is an angle formed by the first straight line P1 connecting the optical fiber core wire and the center of the tensile body and the second straight line P2 connecting the notch tip portion in Examples 1 to 4 of the present invention and Comparative Example 1. θ, the number of good cases (indicated by ◯) when divided 50 times, and the number of cases of poor (indicated by x) when divided 50 times are shown. Here, the evaluation of the take-out property of the optical fiber core is carried out by putting a 10 mm incision into the end of the optical fiber cable with a tool such as a nipper, dividing it into two sheath pieces, and by hand an optical fiber core for the end of 10 mm. When the optical fiber core wire comes out naturally without doing anything when the two sheath pieces of 10 mm are torn 2 m with both hands after taking out the wire, mark it as a good division and In the case where the optical fiber line of sight is buried in the sheath piece, it is marked as “poor” because it is a defective division.

In addition, the material and dimension of each component in each Example 1-4 and the comparative example 1 are as follows.
The dimensions of the tensile body are short side length × long side length = 0.27 mm × 0.55 mm, and are aramid-FRP. The type of sheath is non-halogen flame retardant polyethylene. The diameter of the optical fiber core wire is 0.25 mm, and the dimension of the sheath is 2.0 mm × 3.1 mm.

In all of Examples 1 to 4 and Comparative Example 1, the position of the tip end of the first notch and the position of the tip end of the second notch 32 are shifted, and an optical fiber cable is prototyped.
In Example 1, the angle θ formed by the first straight line P1 and the second straight line P2 is 32 degrees, in Example 2, the angle θ is 43 degrees, in Example 3, the angle θ is 55 degrees, and in Example 4, the angle θ is 69. In the comparative example 1, the angle θ is 80 degrees, and in the comparative example 2, the angle is 90 degrees.
In Examples 1 to 4, there are many good divisions compared to bad divisions, while in Comparative Example 1, there are few good divisions compared to bad divisions, and in Comparative Example 2, good divisions. Did not occur at all.

  From the above results, when the operator divides the sheath at the first notch and the second notch and tries to take out the optical fiber core from the sheath, the two strength members are bent in the direction of the short side. Although the sheath split surface is not horizontal with respect to the bending direction of the optical fiber cable, the left and right sheath pieces are separated along the direction in which the sheath splits at an angle with respect to the sheath split surface. How to split. That is, since the direction in which the optical fiber core wire jumps out of the sheath piece has an angle with respect to the split surface of the sheath, the optical fiber core wire can be easily taken out.

Second Embodiment
FIG. 4 shows a second preferred embodiment of the optical fiber cable of the present invention, and FIG. 4 is a cross-sectional view of the optical fiber cable in a plane perpendicular to the longitudinal direction L.
An optical fiber cable 10A according to an embodiment of the present invention shown in FIG. 4 is a drop optical fiber cable that can be used as a pull-in optical fiber cable for pulling into a home such as a home from a trunk optical fiber cable. Regarding the components of the optical fiber cable 10A shown in FIG. 4, the same reference numerals are used for the same portions as the components of the optical fiber cable 10 shown in FIG.

  The sheath 20 is connected to the support line portion 81 via the connecting portion 80. The support wire portion 81 includes a sheath 82 and a support wire 83 covered with the sheath 82. The support wire portion 81 holds the sheath 20 that is the main body portion of the optical fiber cable 10A. The outer diameter of the support wire portion 81 is generally 2.0 to 5.0 mm.

  In the case of the optical fiber cable 10A of FIG. 4 as well, when an operator tries to take out the optical fiber core wire 11 from the sheath 20 by dividing the sheath 20 at the first notch 31 and the second notch 32, it is usually connected. The support wire portion 81 and the cable portion 20 are separated by the portion 80, and after dividing into the state shown in FIG.

<Third Embodiment>
In the embodiment of the present invention shown in FIG. 5, two optical fiber core wires 11 are disposed between the strength members 12 and 13. In this way, a plurality of optical fibers 11 can be disposed between the strength members 12 and 13.

By the way, this invention is not limited to the said embodiment, A various modified example is employable.
As described above, the optical fiber cable of the present invention can be applied to both a drop optical cable having a support line and an indoor optical fiber cable having no support line. Further, the optical fiber cable according to the embodiment of the present invention is not limited to the type of the optical fiber core or the type of material of the sheath (for example, polyvinyl chloride, polyethylene, polyurethane, etc.).

In the above-described embodiment, the strength member (tension member) of the optical fiber cable has a short side length × long side length of 0.27 mm × 0.55 mm, and is made of aramid-FRP (fiber reinforced plastic). However, the strength member is not particularly limited in size and material, and the effects of the present invention can be obtained. In particular, when the long side length is 1.5 times or more than the short side length of the strength member, the effect of the present invention becomes remarkable.
Further, the number of strength members is not limited to two.
The number of optical fiber cores is not limited to one or two, and may be four or eight or more between the strength members 12 and 13.

It is sectional drawing in the surface perpendicular | vertical with respect to the longitudinal direction which shows preferable 1st Embodiment of the optical fiber cable of this invention. It is a figure which shows the mode at the time of dividing | segmenting the sheath of the optical fiber cable of FIG. It is a figure which shows the Example and comparative example of this invention. It is sectional drawing in a surface perpendicular | vertical with respect to the longitudinal direction which shows preferable 2nd Embodiment of the optical fiber cable of this invention. It is sectional drawing in a surface perpendicular | vertical with respect to the longitudinal direction which shows preferable 3rd Embodiment of the optical fiber cable of this invention. It is a figure which shows the mode at the time of dividing | segmenting the sheath of an optical fiber cable in case the cross-sectional shape of a tensile strength body is circular shape in the conventional optical fiber cable. It is a figure which shows the mode at the time of dividing | segmenting the sheath of an optical fiber cable in case the cross-sectional shape of a tensile strength body is a rectangular shape in the conventional optical fiber cable.

Explanation of symbols

10 Optical fiber cable 12, 13 Strength member 20 Sheath 31 First notch 31D First notch tip 32 Second notch 32D Second notch tip P1 First straight line P2 Second straight line θ First straight line P1 and second straight line Angle formed by P2

Claims (1)

An optical fiber core,
At least a pair of strength members disposed on both sides of the optical fiber core in parallel with the optical fiber core;
In the optical fiber cable having a sheath that integrally covers the optical fiber core wire and the pair of strength members,
In the vertical cross section with respect to the longitudinal direction of the optical fiber cable, the center of the optical fiber core and the center of each of the pair of strength members are located on substantially the same straight line,
The cross-sectional shape of the pair of strength members is flat so that the short side comes in a direction substantially perpendicular to the first straight line connecting the optical fiber core and the center of the strength member,
The sheath has a first notch for taking out the optical fiber core formed on one surface portion across the first straight line, and an optical fiber core wire taken out on the other surface portion. A second notch,
The angle formed by the first straight line of the plurality of strength members and the second straight line connecting the distal end portion of the first notch and the distal end portion of the second notch of the sheath is 70 degrees or less. Fiber optic cable.

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