JPH04372918A - Optical fiber unit - Google Patents

Abstract

PURPOSE:To provide an optical fiber unit causing no lay ratio difference due to the position of tape cores stored in an optical cable by specifying the cross section shape of the groove of a spacer, laminating multiple tape cores to form a bundle, and rotating and storing the bundle along the longitudinal direction in the spacer. CONSTITUTION:A bundle 2 laminated with multiple tape cores 1 and having a circular or square outer shape is rotated and stored in the longitudinal direction in the groove 4 of a spacer 3. The opening section of the spacer 3 is closed by a cover 5, and press-winding 6 is applied on the periphery of the spacer 3. The inner shape of the groove 4 is practically a circular shape, and the maximum inner diameter is two times the width of the tape cores 1 or below. The bundle 2 is rotated in the spacer 3, the tape cores 1 are twisted, no lay ratio difference is generated due to the position of the tape cores 1 when a cable is formed, and the slack control is facilitated for forming a unit.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the structure of an optical fiber unit used in an optical fiber cable.

0002

2. Description of the Related Art As a unit structure in which a plurality of optical fibers are accommodated in a single groove spacer, for example, Japanese Patent Laid-Open No. 55
As described in Japanese Patent No. 45087, an optical cable using a plastic spacer extruded into a substantially U-shaped cross section is known. FIG. 8 is a cross-sectional view thereof, in which 21 is a U-shaped spacer, 22 is an optical fiber,
23 is an optical fiber bundle, 24 is a tension member,
25 is a pressure winding, and 26 is a sheath.

[0003] In this optical cable, an optical fiber 22 or an optical fiber bundle 23 is housed in a U-shaped one-groove spacer, that is, a U-shaped spacer 21 to form an optical fiber unit. A plurality of optical fiber units are further twisted together around the tension member 24, and a tape wrapping 25 and a sheath 26 are sequentially applied thereon to form a cable. In an optical cable using an optical fiber unit having this structure, an optical fiber or an optical fiber bundle is housed in a single groove spacer. Therefore, since the U-shaped spacer, which is the outer sheath of the optical fiber unit, is not closed and does not have a sealed structure, it has the following characteristics. ■
When performing post-branching work on the optical cable at the intermediate portion of the optical cable after it has been laid, it is possible to take out the optical fibers individually from within the optical fiber unit. ■ It is easy to take out the optical fiber during connection work at the terminal section. However, in the above optical cable,
When attempting to apply a tape core formed by forming a plurality of optical fibers into a tape shape for the purpose of increasing the number of fibers and reducing the diameter of a cable, the following problems arise.

[0004] In order to realize multi-core fibers, it is necessary to laminate a plurality of tape core wires and accommodate them in a single groove spacer. Furthermore, in order to take advantage of the above-mentioned advantage (2), it is necessary to arrange the spacer so that the open part always faces the outside of the cable. Of course, in the structure of Fig. 8, since the outer shape of the spacer is square, such an arrangement is inevitable, but if the outer shape of the spacer is round, the open part always faces outward. It needs to be placed like this.

[0005] Furthermore, in an optical cable in which a plurality of tape fibers are stacked and housed in a U-shaped spacer, the tape fiber arranged in the outermost layer in the optical fiber unit is always on the outside, and the tape fiber in the innermost layer is always on the outside. Since the core wires are always present on the inside, the twisting rate varies depending on the position of the tape core wire in the optical fiber unit, which causes a difference in the length of the tape core wires accommodated in the cable. become.

[0006] Normally, in optical cables with a unit structure, manufacturing of the optical fiber unit and assembly of the units are performed in separate processes, but in this case, when manufacturing the optical fiber unit, the twisting difference is adjusted according to the position of the tape core wire. This will have to be added to each tape core. however,
It is difficult to precisely control the difference in the extra length of the tape cores during unitization. For example, it is possible to vary the collective length of the tape cores by changing the tension supplied to each tape core from the supply device. Even so, meandering occurs in the tape core wire with a large extra length in a straight portion of the pass line, which adversely affects transmission characteristics.

[0007]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is an optical cable that is composed of an optical fiber unit that accommodates a plurality of tape cores. It is an object of the present invention to provide an optical fiber unit in which a difference in twist rate does not occur due to

[0008]

Means for Solving the Problems The present invention provides an optical fiber unit in which a plurality of optical fibers formed into a tape shape are accommodated in a spacer having a groove. The groove of the spacer has a substantially circular cross-sectional shape with a maximum inner diameter not more than twice the width of the tape core, and the tape core has a plurality of layers stacked to form a bundle. The bundle is housed in a spacer while being rotated along the longitudinal direction, and the invention according to claim 2 provides a method for manufacturing an optical fiber unit, in which a tape fed out from a rotating supply device is provided. The core wire is guided to a collecting die that rotates in synchronization with the rotation of the supply device, and a plurality of tape core wires are laminated at the collecting die part to form a bundle, and the bundle that has passed through the collecting die is The spacer is inserted into a spacer that has a substantially circular shape with a maximum inner diameter of not more than twice the width of the tape core wire and has an open portion along the longitudinal direction, and the spacer has an open portion in the longitudinal direction of the spacer. It is characterized by the fact that it can be taken away after it is closed.

[0009]

[Operation] According to the present invention, since the bundle is rotated and the tape core wires are twisted together within the spacer of the optical fiber unit, there is no difference in the twist rate depending on the position of the tape core wires when the cable is formed. Therefore, there is no need to strictly control the extra length when unitizing.

[0010] Furthermore, by making the inner shape of the cross section of the spacer substantially circular, and by making the maximum inner diameter of the spacer less than twice the width of the tape core wire, the arrangement of the tape core wires within the spacer can be prevented. , it is possible to realize a unit with good characteristics without replacement. In other words, when a unit containing bundled tape fibers is subjected to an external force such as bending, the bundle rotates in the longitudinal direction, which may cause the stacked tape fibers to be misaligned. There is. At this time, if the inner surface shape of the spacer has a corner, for example, a U shape, as shown in FIG. The tape gets caught in this area, and the tape core is subjected to local stress at this area. As shown in FIG. 4(B), by making the cross-sectional shape of the groove of the spacer 3 circular, even if the tape core wires 1 are misaligned, they will not get caught in the grooves, causing local stress. can be prevented.

Furthermore, by setting the maximum inner diameter of the groove of the spacer to less than twice the width of the tape core, the deviated tape core can be prevented from completely protruding from the bundle.
It is possible to prevent the arrangement from becoming disordered.

0012

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a sectional view of an embodiment of an optical fiber unit according to the present invention. In the figure, 1 is a tape core, 2 is a bundle, 3 is a spacer, 4 is its groove, 5 is a lid, and 6 is a pressure winder. The figure (A) shows an example in which the outer shape is circular, and the figure (B) shows an example in which the outer shape is polygonal, for example, quadrangular. It is also possible to have an external shape that allows them to be lined up without gaps when made into cables. In the case shown in Figure (B), it is easy to arrange the spacer 3 so that its opening faces toward the outside of the cable. As shown in FIG. 7, the tape core wire 1 is
For example, four optical fibers 15 are arranged and integrated using an ultraviolet curing resin 16 or the like. A plurality of tape core wires 1 are stacked to form a bundle 2. The spacer 3 is made of a suitable material such as a synthetic resin such as polyethylene, and has an opening along the longitudinal direction in the upper part. The opening is closed by a lid 5. The groove 4 inside the spacer 3 in which the bundle 2 is accommodated has a substantially circular shape, and its maximum inner diameter is not more than twice the width of the tape cable core 1. The bundle 2 is placed in the groove 4,
After being rotated in the longitudinal direction and housed, a lid 5 is attached and a pressure wrap 6 is applied around the lid 5.

The width of the opening of the spacer 3 may be made larger than the minimum width of the bundle 2, and the lid 5 may be attached after the bundle 2 is inserted through the opening. The bundle 2 may be inserted with the opening made slightly wider using a jig or the like, and the lid 5 may be attached after the bundle 2 is returned to its normal state.

FIG. 2 is a sectional view of another embodiment of the optical fiber unit of the present invention. Similar to Figure 1, (A) figure is
The outer shape is circular, and the figure (B) shows an example in which the outer shape is square. In the figure, parts similar to those in FIG. 1 are denoted by the same reference numerals, and explanations thereof will be omitted. 7 is a butt portion. In this embodiment, after the bundle 2 is rotated in the longitudinal direction and accommodated in the spacer 3, the open portions of the spacer 3 are butted together to form an abutment portion 7, on which a pressure winding 6 is applied. . In the case of the figure (A), the shape of the spacer 3 is extremely simple, easy to manufacture, and inexpensive.

FIG. 3 is a cross-sectional view for explaining the structure of an optical cable using the optical fiber unit described in FIG. 2(A). The optical fiber unit 8 is arranged spirally or in parallel around the tension member 9 so that the abutting portion 7 thereof is always located on the outer peripheral side, and a sheath 10 is provided thereon.

A prototype example of the optical cable shown in FIG. 3 will be explained. The optical fiber unit has a thickness of 0.4 mm, a width of 1.1 mm,
A bundle made of three stacked 4-fiber ribbons with an inner diameter of 1.
Twist it in the longitudinal direction and store it in a 5mm circular spacer.
The open parts of the spacers are butted against each other and pressed and rolled. There was no change in the transmission loss of the optical fiber measured between manufacturing steps, and it exhibited extremely stable characteristics. When repeated bending tests were conducted on the manufactured optical fiber unit, no measurable increase in transmission loss was observed even when the cable was wound at ±180° around a mandrel with a radius six times the outer diameter of the cable. Ta. Additionally, since the butting part of the unit is always located on the outer periphery of the cable, the time required to branch the optical fibers at the middle of the cable can be significantly reduced.

FIG. 5 shows an example of the optical fiber unit manufacturing apparatus of the present invention. The optical fiber unit described in FIG. 2(A) is manufactured. In the figure, 1 is a tape core wire,
3 is a spacer, 6 is a pressure winder, 11 is a supply bobbin, 12 is a collecting die, 13 is a first die, and 14 is a second die. Further, the cross-sectional shapes of the spacer at the positions indicated by A, B, and C are shown in FIGS. 6A, 6B, and 6C.

The supply bobbins 11 are provided in the same number as the number of tape core wires to be bundled, and supply the tape core wires 1 while rotating in the same direction as a whole. The tape core wire 1 fed out from the supply bobbin 11 is guided to a collecting die 12 that rotates in the same direction in synchronization with the rotation of the supply bobbin 11, and a plurality of tape core wires 1 are stacked to form a bundle. The bundle is inserted into the spacer 3 with the first die 13, and after the open portions of the spacers 3 are butted together with the second die 14, the bundle is wrapped with pressure 6.

The cross-sectional shape of the spacer 3 is as shown in FIG.
Although the opening is a little small as shown in (A), the first die 13 allows the spacer 3 to open as shown in FIG. 6(B).
The opening is opened wide to facilitate insertion of the bundle into the bundle. Thereafter, the openings are butted together using the second die 14, as shown in FIG. 6(C).

Note that when manufacturing the optical fiber unit of the embodiment described in FIG. 1, if the lid 5 is attached using the second die 14 in FIG. 5, the manufacturing apparatus in FIG. It can be used to manufacture optical fiber units.

[0021]

As is clear from the above description, according to the present invention, since the tape core wires are twisted together to form a bundle within the space, when the unit is bent, the outer tape is always bent. This solves the problem of the inner tape being compressed when it is stretched, and a unit with excellent bending properties can be realized. Furthermore, when this optical fiber unit is made into a cable, by arranging it in a spiral, an optical cable with even better bending properties can be realized.

[0022] In particular, when the open part of the spacer is placed on the outer periphery of the cable in consideration of later branching when it is made into a cable, the difference in the twist rate depending on the position of the tape core wires can be further eliminated, so that the unit There is no need to strictly control the extra length of the tape core during processing. Furthermore, the inner shape of the cross section of the spacer is substantially circular, and
By making the maximum inner diameter of the spacer less than twice the width of the tape fibers, it is possible to realize an optical fiber unit with good characteristics without disarrangement or replacement of the tape fibers within the spacer. .

[Brief explanation of drawings]

FIG. 1 is a sectional view of an embodiment of an optical fiber unit of the present invention.

FIG. 2 is a sectional view of another embodiment of the optical fiber unit of the present invention.

FIG. 3 is a cross-sectional view of an example of an optical cable using the optical fiber unit of the present invention.

FIG. 4 is an explanatory diagram of the operation of the present invention.

FIG. 5 is a schematic diagram of an example of an optical fiber unit manufacturing apparatus of the present invention.

6 is an explanatory diagram of the manufacturing process in FIG. 5. FIG.

FIG. 7 is a cross-sectional view of an example of a ribbon core used in the present invention.

FIG. 8 is a cross-sectional view of an example of an optical cable using a conventional single-groove spacer.

[Explanation of symbols]

1 Tape core wire 2 Bundle 3 Spacer 4 That groove 5 Lid 6　Temaki roll 7 Butt part

Claims (2)

[Claims] 1. An optical fiber unit in which a plurality of optical fibers formed into a tape shape are accommodated in a spacer having a groove, in which the groove of the spacer has a cross-sectional shape such that the maximum inner diameter of the tape fiber is It has a substantially circular shape with a width not more than twice the width, and a plurality of the tape core wires are stacked to form a bundle, and the bundle is housed in a spacer while being rotated along the longitudinal direction. An optical fiber unit characterized by: [Claim 2] The tape cores fed out from the rotating supply device are guided to a collecting die that rotates in synchronization with the rotation of the supply device, and a plurality of tape cores are laminated in the collecting die section to form a bundle. In addition, the bundle that has passed through the collecting die is treated so that the groove has a substantially circular cross-sectional shape with a maximum inner diameter of not more than twice the width of the tape core wire, and has an open portion along the longitudinal direction. 1. A method of manufacturing an optical fiber unit, which comprises inserting the optical fiber unit into a spacer, closing an open portion in the longitudinal direction of the spacer, and then taking it out.