JP2005292551A - Multi-core optical fiber branch structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a multi-core optical fiber branch structure capable of stably fixing a branching section while making the branching section compact. <P>SOLUTION: When the multi-core optical fiber 1 is branched into two or more, the branching section is caught between two upper and lower soft resin sheets 14 and 15 together with end sections of protection tubes 3 coated on branched optical fibers. Such a short width is given to the sheets 14 and 16 that the sheets are not stuck to each other, and at least an entire sheet part is stored and fixed in a thermo-shrinkable tube 16. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a multi-fiber optical fiber branch structure in which a branch portion is sandwiched between two sheets when a multi-fiber optical fiber is branched.

  Conventionally, when a multi-core optical fiber, for example, a tape core wire is branched into two or more branches, the branch portion may be reinforced by sandwiching the branch portion of the tape core wire between upper and lower sheets with an adhesive. At the time of this branching, when the tape core is separated into a single-core optical fiber, the single-core optical fiber is inconvenient to handle and may be broken. An example of this type of conventional multi-core optical fiber branching structure is shown in FIGS. The illustrated example is a case where the multi-core optical fiber 1 before branching is an eight-core tape, and the eight-core tape (multi-core optical fiber) 1 is branched into two. The optical fiber (single-core optical fiber) 2 is divided into two groups of four, each is accommodated in the protective tube 3, and the branch part includes the end of the protective tube 3, and two sheets with adhesive on the upper and lower sides 4 and 5 are sandwiched and fixed. In addition, the adhesive of a sheet should just be apply | coated to at least one of the upper and lower sheets 4 and 5. FIG.

As shown in the figure, in the conventional multi-fiber optical fiber branch structure, the upper and lower sheets 4 and 5 are firmly adhered to both sides a of the side-by-side protection tubes 3 to fix the branch portions and the ends of the protection tubes 3. As described above, the widths of the sheets 4 and 5 are sufficiently wide.
JP 2002-350650 A

In the conventional multi-core optical fiber branching structure, the widths of the sheets 4 and 5 are sufficiently wider than the entire width of the side-by-side protection tubes 3 in order to sandwich and securely fix the side-by-side protection tubes 3 between the upper and lower sheets 4 and 5. Therefore, there is a problem that the large sheets 4 and 5 are necessary, and the sheet 4, 5 portion, that is, the branch structure portion occupies a wide space.
The diameter of the protective tube 3 is, for example, 2 mmφ, which is larger than the diameter of the optical fiber 2 and reduces the adhesion between the sheets 4 and 5, so that the sheets 4 and 5 are peeled off at the portion of the protective tube 3. There is a risk that.

  The present invention has been made to eliminate the above-described conventional drawbacks, and when a multi-fiber optical fiber is branched using a sheet sandwiched from above and below, the branching portion is stably fixed to improve long-term reliability. An object of the present invention is to provide a multi-core optical fiber branching structure that can make the branching structure compact.

The present invention that solves the above-mentioned problems is that when a multi-fiber optical fiber is branched into a plurality of optical fibers having a smaller number of cores than the multi-fiber optical fiber, the branch portions of the protective tubes are respectively covered with the branched optical fibers. In the multi-core optical fiber branching structure sandwiched between two soft resin sheets, including the end part,
The width of the sheet is such a short width that the upper and lower sheets are not bonded to each other, and at least the entire sheet portion is accommodated and fixed in a heat-shrinkable tube.

  According to a second aspect of the present invention, in the multi-core optical fiber branching structure according to the first aspect, the width of the upper and lower sheets is approximately the same as the total width of the plurality of protective tubes arranged in contact with each other.

  According to a third aspect of the present invention, in the multi-core optical fiber branching structure according to the first or second aspect, the multi-core optical fiber before branching is a tape core.

  According to a fourth aspect of the present invention, in the multi-fiber optical fiber branching structure according to the first or second aspect, the multi-fiber optical fiber before branching is configured so that a single-core or multi-core optical fiber is accommodated in the coated tube. The end portion is also sandwiched between two upper and lower sheets.

According to the present invention, since the adhesive force between the sheets is not utilized, the width of the sheet can be reduced to, for example, about the entire width of the side-by-side protection tubes, and thus the branch structure portion can be made compact.
On the other hand, the protective tube is sandwiched between narrow sheets and fixed with a heat-shrinkable tube, so that the narrow width of the sheet is not a problem and stable fixing of the bifurcation is achieved, improving long-term reliability. .

  The case where the multi-core optical fiber before branching is a tape core as in claim 3 is suitable for a structure in which the branching portion is sandwiched between upper and lower sheets, and is suitable as an object to which the present invention is applied.

  When the multi-core optical fiber before branching is a single-core or multi-core optical fiber accommodated in a protective tube as in claim 4, the sheet width is set to firmly fix the pre-branch side protective tube. Although it tends to be wide, according to the present invention, even in such a case, the branched structure portion does not become wide.

  Hereinafter, a multi-core optical fiber branching structure embodying the present invention will be described with reference to the drawings.

  FIG. 1 shows a multi-core optical fiber branching structure 10 according to an embodiment of the present invention. (A) is a partially cutaway plan view, (b) is a partially cutaway side view, and (a) is FIG. FIG. 2B is an enlarged cross-sectional view taken along the line BB in FIG. The illustrated example is a case where the multi-core optical fiber 1 before branching is an eight-core tape, and the eight-core tape (multi-core optical fiber) 1 is branched into two. The optical fibers (single-core optical fibers) 2 are divided into two groups of four, and each is in contact with each other and accommodated in a protective tube 3 side by side. It is sandwiched between upper and lower soft resin sheets 14 and 15 coated with an agent on the inner surface. The entrance portion of the optical fiber 2 to the protective tube 3 is fixed to the end portion of the protective tube 3 with an adhesive b.

  The width of the sheets 14 and 15 is such a short width that the upper and lower sheets 14 and 15 are not bonded to each other. In the embodiment, as shown in FIG. Yes, the upper and lower sheets 14 and 15 are not in contact with each other. And the whole longitudinal direction of the sheet | seats 14 and 15 part and its front-and-back part are accommodated and fixed with the heat contraction tube 16. FIG. As a specific work procedure, the heat-shrinkable tube before heating is passed through the tape core wire 1, the branching portion is sandwiched between the sheets 14 and 15 from above and below, and then slid to cover the sheet 14 and 15 parts, Heat to shrink and fix the bifurcation as shown.

  The thickness of the sheets 14 and 15 is 0.5 mm, for example, and the diameter of the protective tube 3 is 2 mmφ. The material of the sheets 14 and 15 is a soft resin used for general optical fiber sheets. For example, polyimide is preferable, but polyethylene terephthalate, low density or high density polyethylene, polypropylene, polyester, nylon 6, nylon 66, ethylene-tetrafluoroethylene copolymer, poly-4-methylpentene, polyvinylidene chloride, plasticized polyvinyl chloride, polyether ester copolymer, ethylene-vinyl acetate copolymer, flexible polyurethane, etc. it can. As the material of the protective tube 3, nylon, Hytrel (trademark of DuPont), or the like can be used. As the material of the heat shrinkable tube 16, silicone resin, vinyl resin (crosslinked polyolefin), fluorine resin, or the like can be used. Also, the tape core wire 1 in the illustrated example is obtained by simply aligning optical fibers 2 that are 250 μm UV strands and fixing them with an adhesive as shown in FIG. Even if the tape core before branching is a tape core 1 ′ having a coating 1 a as shown in FIG. 3, the same branching process can be performed.

In the multi-fiber optical fiber branching structure 10 described above, the widths of the upper and lower sheets 14 and 15 are about the entire width of the protective tubes 3 arranged side by side as shown in the figure, compared with the conventional one shown in FIGS. It is quite narrow. Therefore, the branch structure portion can be made compact.
The narrow upper and lower sheets 4 and 5 are adhered to the upper surface or the lower surface of the protective tube 3, respectively, but the sheets 14 and 15 are not in contact with each other and are not adhered to each other. However, since the entire sheet 14 and 15 portion is housed and fixed by the heat shrinkable tube 16, the branch portion is stably fixed and long-term reliability is improved.

  In the above embodiment, the separated eight single-core optical fibers 2 are divided into two groups of four and accommodated in each protective tube 3, but as shown in FIG. 1 may be branched into two four-core ribbons 22 so that each four-core ribbon 22 is accommodated in two protective tubes 3.

  Further, as shown in FIG. 5 (a), the 8-fiber ribbon 1 is branched into four 2-fiber ribbons 32, and each 2-fiber ribbon 32 is divided into four protective tubes 3, respectively. It is good also as a branched structure to accommodate.

  Further, the multi-core optical fiber 1 may be branched in such a manner that a single-core optical fiber and a multi-core optical fiber are mixed. FIG. 5 (b) shows an example. In the example shown in the figure, the protective tube 3 is branched, and each protective tube 3 has two two-core ribbons 32, one A two-core tape core wire 32, one single-core optical fiber 2, and one single-core optical fiber 2 are accommodated.

In each of the above-described embodiments, the multi-core optical fiber 1 before branching is the tape core wire 1, but the multi-core optical fiber before branching is a single core or a single core in the coated tube 18 as shown in FIGS. The structure which accommodated the multi-fiber optical fiber may be sufficient.
The multi-fiber optical fiber 17 before branching shown in FIGS. 6 and 7 is one in which one 8-fiber ribbon 1 is accommodated in a coated tube 18.
Further, the multi-fiber optical fiber 27 before branching shown in FIG. 8A is one in which two four-core tape core wires 42 are accommodated in the coated tube 18.
Further, the multi-fiber optical fiber 37 before branching shown in FIG. 8 (b) is one in which eight single-core optical fibers 2 are accommodated in the coated tube 18.

BRIEF DESCRIPTION OF THE DRAWINGS The multi-core optical fiber branch structure of one Example of this invention is shown, (A) is a partial notch top view, (B) A partially notched side view. (A) is an AA expanded sectional view of Drawing 1 (a), and (b) is an BB expanded sectional view of Drawing 1 (a). It is sectional drawing which shows the other Example of the multi-core optical fiber before a branch in FIG. 1, FIG. It is sectional drawing which shows the other Example of the optical fiber after a branch. (A), (b) is a sectional view showing still another embodiment of the optical fiber after branching. The multi-core optical fiber branching structure of the other Example of this invention is shown, (A) is a partial notch top view, (B) It is a partially notched side view. It is CC expanded sectional drawing in FIG. (A), (b) is sectional drawing which shows the other Example of the multi-core optical fiber before a branch in FIG. 6, respectively. It is a partial notch top view which shows the conventional multi-core optical fiber branch structure. It is DD expanded sectional drawing of FIG.

Explanation of symbols

1, 1 'multi-core optical fiber (tape core)
2 Single-core optical fiber 3 Protective tube 10 Multi-fiber optical fiber branching structure 14, 15 Sheet 16 Heat-shrinkable tube 18 Coated tubes 17, 27, 37 Multi-fiber optical fiber

Claims (4)

When a multi-core optical fiber is branched into a plurality of optical fibers with fewer cores than the multi-core optical fiber, the bifurcated portion includes two ends, including the end of the protective tube that covers each of the branched optical fibers. In a multi-core optical fiber branching structure sandwiched between sheets of soft resin,
A multi-core optical fiber branching structure characterized in that the width of the sheet is short enough to prevent the upper and lower sheets from being bonded to each other, and at least the entire sheet portion is accommodated and fixed in a heat-shrinkable tube.   The multi-core optical fiber branching structure according to claim 1, wherein the width of the upper and lower sheets is approximately the same as the total width of the plurality of protective tubes arranged in contact with each other.   3. The multi-core optical fiber branching structure according to claim 1, wherein the multi-core optical fiber before branching is a tape core.   The multi-core optical fiber before branching has a configuration in which a single-core or multi-core optical fiber is accommodated in a coated tube, and the ends of the coated tube are also sandwiched between two upper and lower sheets. Item 3. The multi-core optical fiber branching structure according to Item 1 or 2.

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