JP2005148462A - Method for branching optical fiber cable, assembly method of closure, and closure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To branch an optical fiber cable such as a multi-core drop cable behind the middle without cutting a supporting line. <P>SOLUTION: After laying an optical cable 1 provided with the supporting line 3 in parallel along the side part of the cable body, the supporting line 3 is separated from the cable body without cutting the supporting line 3, and after fixing the supporting line 3 separated from the cable body to a draw-near maintenance means 17 to maintain a draw-near state, an optical fiber 2a of the cable body separated from the supporting line 3 is cut and connected to an optical fiber 7a of an optical fiber cable for branching. Then, the supporting line 3 is drawn near and brought into a curved state, therefore, a complementary length of the optical fiber 2a can be obtained by the bent part of the supporting line 3. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an optical fiber cable branching method, a closure assembling method, and a closure used for intermediate post branching of an optical fiber cable.

  In an optical transmission line using an optical fiber, for example, in the construction of an optical fiber network, an intermediate post branching technique is required in which an optical fiber cable is first laid and then the optical fiber cable is branched from the middle. Conventionally, as an optical fiber cable, a slot type cable, a multi-core drop cable, and the like are known.

As illustrated in FIG. 5, the multi-core drop cable has support wires 3 arranged side by side on the side of a cable body 2 (also referred to as an element). The cable body 2 includes a plurality of optical fibers 2a and a pair of tension members 2b disposed on both sides of the optical fiber 2a in an outer sheath 2c. Moreover, the support wire 3 has a configuration in which the outer periphery of the steel wire 3a is covered with the outer skin 3b.
As a method of branching the multi-core drop cable 1 after the middle, the supporting wire 3 and the tension member 2b are cut without cutting the optical fiber 2a, and the cut cables 1 on both sides are pulled toward each other to obtain the extra length of the optical fiber 2a. There is a method to secure the space in the closure. At the time of branching after the middle, the necessary optical fiber 2a is cut and the optical fiber 2a is connected to the optical fiber of the branching optical fiber cable.

A slot-type optical cable includes a slot in which a number of spiral grooves for accommodating optical fibers are formed on an outer periphery, an optical fiber accommodated in the groove of the slot, and a sheath covering the outside of the slot and the optical fiber. It is an optical fiber cable of the composition provided with.
In this type of optical fiber cable, since the optical fiber is housed in a spiral groove, the length of the optical fiber is longer than the length of the slot. It is easy to remove from the box. The intermediate post-branching of the optical fiber cable is performed by connecting the optical fiber taken out from the slot to the optical fiber of the branching optical fiber cable (see, for example, Patent Document 1).
JP-A-8-160231

However, the slot type cable has various restrictions such as a large outer diameter, a heavy weight, and a high installation cost.
Moreover, in the conventional post-intermediate branching method for a multi-core drop cable, it is necessary to cut both the support wire and the tension member. For this reason, stress may be applied to the optical fiber core during work, and the optical fiber core may be damaged.

  The present invention has been made in view of the above circumstances, and a method of branching an optical fiber cable and an assembly of a closure capable of branching an optical fiber cable such as a multi-core drop cable after the middle without cutting the support wire. It is an object to provide a method and a closure.

  In order to solve the above-mentioned problems, the present invention provides an optical fiber for branching an optical fiber taken out from the cable body of the optical fiber cable after laying an optical fiber cable having support wires arranged in parallel on the side of the cable body. A method of branching an optical fiber cable connected to an optical fiber led out from a cable, wherein the support line and the cable body are separated without cutting the support line, and the support line separated from the cable body An optical fiber characterized in that the optical fiber of the cable main body separated from the support line is cut and connected to the optical fiber of the branching optical fiber cable after being fixed to the drawing maintaining means and maintained in the drawn state Provide a cable branching method.

  In addition, the present invention provides an optical fiber that is laid out from an optical fiber cable for branching after an optical fiber cable having a support wire arranged in parallel on a side portion of the cable main body is laid out. A closure assembling method for connecting to a fiber and accommodating a connecting portion of both optical fibers in a closure sleeve of the closure, wherein the support line and the cable body are separated without cutting the support line, and the cable After fixing the support line separated from the main body to the drawing maintaining means and maintaining the drawing state, the optical fiber of the cable main body separated from the support line is cut and connected to the optical fiber of the branching optical fiber cable. And a connecting sleeve of the two optical fibers is housed in a closure sleeve together with the attraction maintaining means. To provide a method of assembling a manager.

Further, according to the present invention, an optical fiber and a branching optical fiber cable which are taken out from the cable body of the optical fiber cable, in which an optical fiber cable in which support wires are arranged in parallel on the side of the cable body are inserted in the longitudinal direction of the closure sleeve. A connection portion with the optical fiber led out from the optical fiber is a closure that is accommodated in the closure sleeve, and is separated from the optical fiber retaining portion for retaining the optical fiber of the optical fiber cable for branching, and the cable body Pulling and maintaining having a support line fixing part that fixes the support line at least in two places, and a hook part that maintains a curved state of the support line by hooking an intermediate part of the support line fixed to the support line fixing part Provided is a closure characterized in that the device is housed in a closure sleeve.
When three or more support wire fixing portions are provided, at least the hooking portion may be provided between any two of the support wire fixing portions.

According to the present invention, an extra length of the optical fiber can be obtained by fixing the support line of the optical fiber cable and maintaining it in a drawn state, as much as the support line is bent. Therefore, it becomes easy to optically connect the optical fiber of the cable main body of the optical fiber cable to the optical fiber of the branching optical fiber cable, and the optical fiber cable can be branched after the middle.
Since the optical fiber cable can be branched after the middle without cutting the support wire, the optical fiber core taken out from the optical fiber cable is not stressed during the work, and the optical fiber core is damaged. The problem does not occur.

The best mode for carrying out the present invention will be described below with reference to the drawings.
FIG. 1 is a block diagram showing the internal structure of the closure of the present invention. FIG. 2 is a cross-sectional view showing the internal structure of the closure shown in FIG. FIG. 3 is a cross-sectional view taken along line AA of the closure shown in FIG. FIG. 4 is an end view of the closure shown in FIG.

The optical fiber cable 1 to which the closure 10 of the present embodiment is applied is one in which a support wire 3 is juxtaposed on the side of a cable body 2 provided with a covering such as a synthetic resin. An example of the optical fiber cable 1 is a multi-core drop cable 1 configured as shown in FIG.
The present invention can be applied to an intermediate rear branch (branch after cable laying) of the optical fiber cable 1 installed in the aerial space.

  The multi-core drop cable 1 shown in FIG. 5 has a support wire 3 arranged in parallel on a side portion of a cable body 2 (element) via a constricted portion 4. The cable body 2 includes a plurality of optical fibers 2a and a pair of tension members 2b disposed on both sides of the optical fiber 2a in an outer sheath 2c. Moreover, the support wire 3 has a configuration in which the outer periphery of the steel wire 3a is covered with the outer skin 3b. The number of the optical fibers 2a in the multi-core drop cable 1 is not particularly limited, but may be, for example, 4 cores, 8 cores, 12 cores, or the like. The multi-core drop cable 1 can separate the cable body 2 and the support wire 3 from the constricted portion 4.

The branching optical fiber cable 7 (hereinafter sometimes simply referred to as “branching optical cable”) is an optical fiber cable constituting a line branched from the optical fiber cable 1. The branching optical cable 7 is not particularly limited. For example, a single-core drop cable or an indoor cable can be used. The single-core drop cable has substantially the same configuration as the multi-core drop cable 1 shown in FIG. 5, and one in which one optical fiber 2a is accommodated in the outer sheath 2c is usually used. The branch optical fiber cable 7 may be provided with a support line, or may not be provided with a support line in parallel (only the element portion).
When the optical fiber 7a of the branching optical cable 7 is optically connected to the optical fiber 2a of the optical fiber cable 1, as shown in FIG. 2, the outer sheath 7c at the tip of the branching optical cable 7 is removed to double the light. The fiber 7a is exposed (exposed).

  As shown in FIG. 1, in the closure 10 of this embodiment, the optical fiber cable 1 is inserted through the longitudinal direction of the closure sleeve 11, and the cable body 2 separated from the support line 3 of the optical fiber cable 1 is the closure sleeve 11. It is designed to be housed inside.

  The configuration, material, and the like of the closure sleeve 11 are not particularly limited, but here, as shown in FIG. 4, as shown in FIG. 4, a pair of main walls 11 a and a pair of positions arranged at opposite positions around the main wall 11 a. The closure sleeve 11 comprised from the side wall parts 11b and 11c is used. The closure sleeve 11 can be formed of a resin such as polypropylene, for example. As shown in FIG. 4, the main wall portion 11a and the side wall portions 11b and 11c are connected to each other so as to be opened and closed by thin hinges 11d and 11e, for example. The closure sleeve 11 can be provided with an engaging portion such as a latch (not shown) at the end edges of the side wall portions 11b and 11c. In this case, the closure sleeve 11 can be closed by engagement of the engagement portion, and can be opened by releasing the engagement of the engagement portion.

As shown in FIGS. 1 and 2, provided on the inner surface side of the closure sleeve 11 is an end face plate 21 disposed at both ends in the longitudinal direction of the closure sleeve 11, and a space for accommodating the packing 23 from the end face plate 21. The partition wall 22 is provided. As shown in FIG. 4 and the like, the end face plate 21 is formed with a cable insertion hole 24 through which the optical fiber cable 1 is inserted and a branching optical fiber cable insertion hole 25 through which the branching optical cable 7 is inserted.
The optical fiber cable 1 is accommodated in a state in which the cable body 2 and the support wire 3 are separated in the closure sleeve 11. The support line 3 penetrates the both end face plates 21 of the closure sleeve 11 without being cut. Further, the cable body 2 and the support wire 3 remain joined on both sides of the closure sleeve 11.
As shown in FIG. 4, the end face plate 21 has a split structure on the side wall portion 11 b side and the side wall portion 11 c side, and the cable insertion hole 24 is provided on the dividing line 21 a of the end face plate 21. . For this reason, the closure 10 can be in a state where the optical fiber cable 1 is inserted into the cable insertion hole 24 by covering the closure sleeve 11 so as to be sandwiched from both sides of the optical fiber cable 1. .

The packing 23 is in close contact with the outer periphery of the optical fiber cable 1 and the branching optical cable 7 inserted through the insertion holes 24 and 25 at both ends of the closure sleeve 11 so that the watertightness inside the closure sleeve 11 can be maintained. As the packing 23, for example, rubber packing made of low hardness rubber or the like can be adopted.
As the structure of the packing 23 that can be in close contact with the outer periphery of the optical fiber cable, for example, a slit (slit) is made from the edge of the insertion hole to the peripheral edge of the packing in accordance with the outer peripheral shape of the optical fiber cable. A structure in which the optical fiber cable can be inserted into the hole, a structure in which the optical fiber cable is divided into two according to the insertion position of the optical fiber cable, and a thin portion 23a in accordance with the insertion position of the optical fiber cable as shown in FIG. A structure in which is formed.
In the place where the optical fiber cable 1 is inserted, the packing 23 can be attached to the outer periphery of the optical fiber cable 1 without cutting the support wire 3 by dividing the packing 23 in half or by inserting a slit. Further, since the branching optical cable 7 is not inserted into the closure 10 when the closure 10 is installed, it is preferable that the packing 23 has a thin portion 23 a for inserting the branching optical fiber cable 7. In the case of the structure in which the thin portion 23a is provided, a through hole is not formed in the packing 23 before the branching optical cable 7 is inserted, which is preferable.

  In the space 27 between the partition walls 22 on both sides in the closure sleeve 11, there are connecting bases 12 extending in the longitudinal direction of the closure sleeve 11 (left and right direction in FIG. 2), and both ends of the connecting base 12 in the longitudinal direction. A drawing maintenance device (pulling maintenance means) 17 having an optical fiber holding portion 13 and a support wire fixing portion 15 provided respectively, and a hooking portion 16 provided at a central portion in the longitudinal direction of the coupling base 12 is accommodated. Yes. As the pulling maintenance tool 17, a configuration in which a plurality of support wire fixing portions 15 are provided at least on the coupling base 12 and the pulling state of the support wire 3 can be maintained is used.

  In the space between the optical fiber retaining portions 13 on the coupling base 12, a connection portion 14 for connecting the optical fiber 2a of the cable body 2 and the optical fiber 7a of the branching optical cable 7 can be accommodated. ing. The connection part 14 should just be what can hold | maintain the connection part of optical fiber 2a, 7a, and can maintain an optical connection state, for example, a mechanical splice, a fusion splicing, etc. can be illustrated. From the viewpoint of workability, a mechanical splice is particularly preferable.

  The optical fiber retaining portion 13 has a plurality of retaining grooves 13 a for retaining the branching optical cable 7. The retaining groove 13a is configured to grip and fix the branching optical cable 7 by pressing and fitting a sheath (not shown) of the branching optical cable 7 into the retaining groove 13a. In addition, the retaining groove 13a presses the outer cover of the branching optical cable 7 with, for example, demon-shaped protrusions (not shown) formed on both sides of the groove to prevent the branching optical cable 7 from being pulled out along the longitudinal direction (retaining) ) You can do it.

  The support line fixing portion 15 includes a bent-end fixing base 15a erected from the connection base 12, and a pressing member 15b fastened to the fixing base 15a by a fastening bolt 15c. Thereby, the support line fixing | fixed part 15 pinches the support line 3 between the fixing stand 15a and the pressing tool 15b, and can fix it now.

As shown in FIGS. 2 and 3, the hooking portion 16 includes a protruding piece 16a projecting from the coupling base 12, and two bent pieces 16b bent at a substantially right angle from the protruding piece 16a and bent in a hook shape. , 16b. As shown in FIG. 1, the hook 16 is provided at one side edge of the short side direction (vertical direction in FIG. 1) perpendicular to the longitudinal direction (left and right direction in FIG. 1) of the coupling base 12. 16 b, 16 b protrudes inward in the short direction of the connection base 12.
The hook part 16 can maintain the support line 3 stretched between the support line fixing parts 15 and 15 on both sides in a curved state by hooking the support line 3 on the bent pieces 16b and 16b. ing. For this reason, the position where the support line 3 of the hook 16 is hooked is disposed away from the straight line passing through the fixing positions (two places) of the support line 3 in the both support line fixing sections 15.

  As shown in FIG. 1, the closure 10 of the present embodiment is not an essential component of the present invention, but a hanging bracket 26 for hanging the closure 10 from the messenger wire 9 can be attached. The hanging bracket 26 may be detachable from the closure 10.

Hereinafter, an example of a procedure for branching the optical fiber cable 1 after the middle using the closure 10 will be described.
First, the cable body 2 and the support line 3 are separated without cutting the support line 3 of the optical fiber cable 1 within a range of a certain section to be accommodated in the closure 10. The separated support wire 3 is bent by drawing using the slack of the cable or the like. The length for pulling the support wire 3 may be about several mm, and a sufficient length can be secured for taking out the optical fiber 2a. The support line 3 in the bent state is hooked on the hook 16 and is held by the support line fixing parts 15 and 15 and is fixed in a curved state.
Further, the outer sheath 2c of the cable body 2 is removed, the tension member 2b is cut and removed, and the optical fiber 2a is exposed without being cut.

Further, the desired optical fiber 2a is taken out, cut, and connected to the optical fiber 7a of the branching optical cable 7. In FIG. 1, only one of the two tip portions generated by cutting one optical fiber 2 a is used to connect to the optical fiber 7 a of the branching optical cable 7.
In some cases, it is also possible to employ a method in which both of the two tip portions generated by cutting one optical fiber 2a are connected to the optical fiber 7a of the branching optical cable 7, respectively. In this case, the optical fiber 2a can be used effectively.

  Further, the closure sleeve 11 is put on the optical fiber cable 1 so as to include a section where the cable body 2 and the support wire 3 are separated. As a result, as shown in FIG. 5, the optical fiber 2a can be accommodated in the closure 10 in a slack state, and an extra length for the intermediate rear branch can be secured.

The optical fiber 2a of the cable body 2 that has not been used for the intermediate rear branch can be accommodated in the closure sleeve 11 in a through-wired state without being cut, as indicated by reference numeral 2t in FIG. The optical fiber 2t can be taken out later when branching becomes necessary and used to connect to the optical fiber 7a of another branching optical cable 7.
It is also possible to branch one optical fiber cable 1 at a plurality of locations. In that case, the optical fiber 2a may be cut at a position to be branched for each optical fiber and optically connected to the optical fiber 7a of the branching optical cable 7.

According to the closure of the present embodiment, the support wire 3 is drawn and fixed and accommodated in a curved state. Therefore, the light extracted by removing the outer skin 2c of the cable body 2 by the amount of the support wire 3 being curved. The extra length of the fiber 2a can be obtained. Therefore, even in the case of an optical fiber cable of a type in which the difference between the cable length and the optical fiber length cannot be obtained, the optical fiber cable 1 can be branched after the intermediate without cutting the support wire 3. Since the intermediate branch can be branched without cutting the support wire 3, no stress is applied to the optical fiber 2a taken out from the cable body 2 during the operation, and the optical fiber 2a is not damaged. Therefore, it is possible to perform branching and connection work safely and reliably.
Since the hooking portion 16 for maintaining the support line 3 in the curved state is provided on one side of the pulling maintenance tool 17, the side opposite to the side where the support line 3 is bent (the lower side in FIG. 1) is the optical fiber 2a. 7a can be used as a space for connection work, and the support wire 3 does not get in the way during the connection work.

At the time of branching in the middle, the installation length of the optical fiber cable is hardly changed, and the transmission characteristics of the optical fiber cable are hardly adversely affected. The operation of intermediate post-branching is very simple and can be performed easily. It becomes possible to branch the line by installing a closure at an arbitrary position of the optical fiber cable already installed in the aerial space.
The configuration for obtaining the extra length of the optical fiber 2a of the cable body 2 is simple, and it is not necessary to secure a special space for accommodating the extra length of the optical fiber 2a. Therefore, the closure can be reduced in weight and size.

  By using a multi-core drop cable as the optical fiber cable, it is possible to employ a light-weight optical fiber cable as compared with the slot type cable. Therefore, the load on the utility pole, support, etc. due to the laying of the optical fiber cable is small, the degree of freedom of the installation position can be increased, and the cost of equipment and the like can be suppressed. In addition, since the diameter of the optical fiber cable is small, the closure can be reduced in weight and size.

Although the present invention has been described based on the preferred embodiments, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the present invention. .
For example, the specific structure, shape and the like of the closure are not limited as long as the idea of the present invention can be embodied.

  The present invention can be used to construct an optical fiber network, for example, in an optical transmission line using an optical fiber, for example.

It is a block diagram which shows the internal structure of the closure of this invention. It is sectional drawing which shows the internal structure of the closure shown in FIG. It is sectional drawing which follows the AA line of the closure shown in FIG. FIG. 2 is an end view of the closure shown in FIG. 1. It is sectional drawing which shows the structure of a multi-core drop cable.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Optical fiber cable, 2 ... Cable main body (element), 2a ... Optical fiber of cable main body, 3 ... Support line, 7 ... Optical fiber cable for branching (optical fiber for branching), 7a ... Optical fiber of optical fiber cable for branching DESCRIPTION OF SYMBOLS 10 ... Closure, 11 ... Closure sleeve, 13 ... Optical fiber holding | maintenance part, 14 ... Connection part of optical fiber, 15 ... Support line fixing | fixed part, 16 ... Hook part, 17 ... Pulling maintenance tool (pulling maintenance means).

Claims (3)

After laying the optical fiber cable (1) in which the support line (3) is arranged side by side on the side of the cable body (2), the optical fiber (2a) taken out from the cable body of the optical fiber cable is split into light for branching. A method of branching an optical fiber cable connected to an optical fiber (7a) led out from a fiber cable (7),
The support line and the cable body are separated without cutting the support line, and the support line separated from the cable body is fixed to the drawing maintaining means (17) and maintained in the drawn state, and then the supporting line is separated. An optical fiber cable branching method comprising: cutting an optical fiber of a cable main body separated from a line and connecting the optical fiber of the branching optical fiber cable. After laying the optical fiber cable (1) in which the support line (3) is arranged side by side on the side of the cable body (2), the optical fiber (2a) taken out from the cable body of the optical fiber cable is split into light for branching. A method of assembling a closure for connecting to an optical fiber (7a) led out from a fiber cable (7), and housing a connecting portion (14) of both optical fibers in a closure sleeve (11) of the closure (10),
The support line and the cable body are separated without cutting the support line, and the support line separated from the cable body is fixed to the drawing maintaining means (17) and maintained in the drawn state. An optical fiber of the cable body separated from the optical fiber is cut and connected to the optical fiber of the optical fiber cable for branching, and a connection portion of both optical fibers is housed in a closure sleeve together with the pulling maintaining means. Assembly method. An optical fiber cable (1) having a support wire (3) arranged side by side on the side of the cable body (2) is inserted through the closure sleeve (11) in the longitudinal direction, and light taken out from the cable body of the optical fiber cable. A connection part (14) between the fiber and the optical fiber (7a) led out from the branching optical fiber cable (7) is a closure accommodated in the closure sleeve,
An optical fiber retaining portion (13) for retaining the optical fiber of the branching optical fiber cable, and a support wire fixing portion (15, 15) for fixing the support wire separated from the cable body at at least two locations; A pulling maintenance tool (17) having a hook portion (16) for maintaining a curved state of the support line by hooking an intermediate portion of the support line fixed to the support line fixing portion is accommodated in the closure sleeve. A closure (10) characterized by:

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