Patent Application
20120243838
The present invention relates to a reinforcing member for collectively reinforcing, as a single body, a plurality of coated optical fibers which have been individually fusion-spliced, and to a reinforcing method using the reinforcing member.
Optical fibers are fusion-spliced to each other by removing fiber coatings of end portions to be fusion-spliced of the optical fibers, and heating and fusing end portions of the exposed glass fiber portions to fusion-splice their end portions. The glass fiber portions fusion-spliced to each other, where the fiber coatings are removed, are weak in mechanical strength, and therefore are protected and reinforced by a reinforcing member. This reinforcing member is usually formed by accommodating a rod-shaped tensile strength body and a tube-shaped heat-fusible adhesive member in a heat-shrinkable tube which shrinks radially by heating.
Further, by the development of an optical communication network, many coated optical fibers are handled in many cases. For example, after plural coated optical fibers have been fusion-spliced, each fusion-splicing portion is subjected to reinforcement and the reinforced fusion-splicing portions are accommodated in a junction box collectively. At this time, in case that the fusion-splicing optical fibers are reinforced one by one, large space is required in order to accommodate reinforcing members, so that there is a problem that the junction box becomes large in size. As a method of solving this problem, for example, it has been disclosed in Patent Document 1 that: in a heat-shrinkable tube, plural heat-fusible adhesive tubes are arranged; a splicing portion of coated optical fibers is inserted into each heat-fusible adhesive tube; and a plurality of fusion-splicing coated-optical-fibers are reinforced by a single reinforcing member collectively.
The reinforcing member 2 is heated by heat from a recess-shaped wall surface constituted by the V-groove 7 or the U-groove 8, and the heat-shrinkable tube 3 shrinks with heat thereby to decrease the vacant space volume in the tube. Simultaneously, the heat-fusible adhesive tube 5 melts thereby to infill the vacant space portion in the heat-shrinkable tube 3, and encloses the exposed fusion-splicing portion and the peripheral portion thereof. Thereafter, the melted heat-fusible adhesive tube 5 is solidified, whereby the heat-shrinkable tube 3, the tensile strength body 4 and the coated optical fibers 1 including the fusion-splicing portions are integrated, and the reinforcement is completed.
According to the reinforcing member disclosed in the above-mentioned Patent Document 1, fusion-splicing portions of the two ribbon-shaped coated optical fibers can be reinforced collectively by the single reinforcing member. Further, by making the tensile strength body square in section, the heat-fusible adhesive tubes can be arranged on four sides, so that fusion-splicing portions of four ribbon-shaped coated optical fibers can be reinforced collectively.
However, since the plural heat-fusible adhesive tubes are arranged oppositely to each other with the tensile strength body between, it is necessary, in order to melt these heat-fusible adhesive tubes uniformly and obtain a good adhesive state, to form the heating surface of the heater platform into the V-shaped or U-shaped wall surface as described above, so that the heater has the special shape and therefore becomes a heating mechanism which creates high cost. Further, since the coated optical fibers are arranged with the tensile strength body between, a clamping part which clamps both sides of the reinforcing part becomes large in size or a plurality of clamping parts become necessary. Therefore, from this point, the high cost is also created.
The invention has been made in view of the above-mentioned circumstances, and one of objects of the invention is to provide a reinforcing member of optical fiber fusion-splicing portion and a reinforcing method thereof, in which plural coated optical fibers can be collectively reinforced in the high density, and a heating mechanism for collective reinforcement can be constituted at a low cost.
A reinforcing member of optical fiber fusion-splicing portion according to the invention, which reinforces fusion-splicing portions of plural single-core optical fibers collectively, includes a heat-shrinkable tube, a rod-shaped tensile strength body which is arranged so that a part of its surface comes into contact with an inner surface of the heat-shrinkable tube, and plural tube-shaped heat-fusible adhesive members which are arranged in the heat-shrinkable tube and into which the fusion-splicing portions of the single-core optical fibers are individually inserted. This reinforcing member is characterized in that all of the plural tube-shaped heat-fusible adhesive members are arranged in one of space portions formed between the tensile strength body and the heat-shrinkable tube. Each gap produced by the tensile strength body, the heat-shrinkable tube, and the plural tube-shaped heat-fusible adhesive members may have such a size that insertion of the single-core coated optical fiber is prevented.
Further, a reinforcing method of optical fiber fusion-splicing portion according to the invention is characterized by reinforcing fusion-splicing portions of plural single-core optical fibers collectively by means of the above reinforcing member.
According to an embodiment of the invention, all the tube-shaped heat-fusible adhesive members, without the tensile strength body between, in one of the space portions formed between the tensile strength body and the heat-shrinkable tube, are arranged in array or in a trefoil formation state. Therefore, as a heater for heat-processing, a heater having a heating surface of not the special shape but the simply planar shape can be used, which can create low cost. Further, the coated optical fibers, without coming into contact with one another by the individual tube-shaped heat-fusible adhesive members, can be efficiently assembled together, being clamped by a clamp part having no especially large size.
With reference to drawings, embodiments of the invention will be described. In the drawings, a reference numeral 10 represents a glass fiber portion, 10a represents a fusion-splicing portion, 11 represents a coated optical fiber, represents reinforcing member, 13 represents a heat-shrinkable tube, 14 represents a tensile strength body, 15 represents a tube-shaped heat-fusible adhesive member, 16 represents a heater, 16a represents a heater wire, 16b represents a heater platform.
Fusion-splicing of optical fibers is performed, as shown in
Generally, protection/reinforcement of the coated optical fiber fusion-splicing portion is individually performed for each coated optical fiber. However, in the embodiment, the plural coated optical fibers, after being individually fusion-splicing, are collectively reinforced together, and a single reinforcing member 12 is used for this collective reinforcement. The reinforcing member 12 according to the embodiment is configured by the heat-shrinkable tube 13 which shrinks in the radial direction by heating, the rod-shaped tensile strength body 14 which is arranged in this heat-shrinkable tube 13, and the plural tube-shaped heat-fusible adhesive members 15.
The heat-shrinkable tube 13 is formed of flexible polyolefin resin. For example, in case that four-core coated optical fibers are collectively reinforced, the heat-shrinkable tube 13 having an inner diameter of about 5 mm before shrinkage is used. Further, the heat-shrinkable tube 13 has a length of 25 mm to 60 mm, which is different depending on fusion-splicing modes.
The tensile strength body 14 is formed of, for example, glass ceramics, and uses a rod-shaped member having the length nearly equal to the length of the heat-shrinkable tube 13. The tensile strength bodies 14 having various sectional shapes can be used such as a cylindrical body and a prismatic body, and preferably a body of the sectional shape having at least one flat surface is used such as a body of a semicircle section.
The tube-shaped heat-fusible adhesive member 15 is formed of a hot-melt adhesive resin which is melted by heat and solidified by cooling thereby to complete adhesion, such as an ethylene polyvinyl acetate resin. This tube-shaped heat-fusible adhesive member 15 uses a tube-shaped member having such an inner diameter that a single-core coated optical fiber (having an outer diameter of 0.25 mm to 0.9 mm) can be readily inserted therein. The tube-shaped heat-fusible adhesive members 15 corresponding to the number of the fusion-splicing optical fibers to be lumped together (four tube-shaped heat-fusible adhesive members in case of four optical fibers) are accommodated in the single heat-shrinkable tube 13.
The plural tube-shaped heat-fusible adhesive members 15 are concentrated and accommodated in one space portion formed between the heat-shrinkable tube 13 and the tensile strength body 14. Namely, though plural space portions can be formed between the heat-shrinkable tube 13 and the tensile strength body 14 depending on the shape of the tensile strength body, also in such a case, the tube-shaped heat-fusible adhesive members 15 are not accommodated decentrally in the plural space portions, but arranged so that all of the tube-shaped heat-fusible adhesive members 15 can be accommodated in one space portion.
The tube-shaped heat-fusible adhesive member 15d may be a rectangular tube formed by deforming a circular tube, or may be formed in the shape having a flat portion by squashing partially a circular arc of the heat-shrinkable tube 13d. Such the shape can be readily formed by accommodating the tensile strength body and the tube-shaped heat-fusible adhesive members in the heat-shrinkable tube in the mode of
In the reinforcing member 12d having this shape, the tensile strength body 14d and the tube-shaped heat-fusible adhesive members 15d are closely filled into the heat-shrinkable tube 13d, and held in contact with one another into the heat-shrinkable tube 13d, whereby it is possible to prevent the tensile strength body 14d and the tube-shaped heat-fusible adhesive members 15d from coming off from the heat-shrinkable tube 13d. Further, in this reinforcing member 12d, since the coated optical fiber cannot be inserted into other portions than the tube-shaped heat-fusible adhesive member 15d, erroneous insertion of the coated optical fiber is prevented and operability can be improved.
In the embodiment, as described above, the tensile strength body is arranged so that a part of its surface comes into contact with the inner surface of the heat-shrinkable tube. This mode is naturally produced in the manufacture of the reinforcing member by gravity of the tensile strength body, so that at least one space portion is formed between the heat-shrinkable tube and the tensile strength body, and an annular space portion is not produced. The heat-shrinkable tube and the tensile strength body have such sizes and shapes that all of the required tube-shaped heat-fusible adhesive members are accommodated in one space portion formed between the heat-shrinkable tube and the tensile strength body.
In case that the collective reinforcement is performed using the thus constructed reinforcing member 12, into the tube-shaped heat-fusible adhesive members 15 arranged in the heat-shrinkable tube 13, one-sided coated optical fibers (single-core coated optical fiber group on the right side or on the left side) of plural pairs of coated optical fibers 11 to be fuse-spliced to each other are inserted in advance prior to fusion-splicing. After all the fusion-splicing of the coated optical fiber in pairs have been completed, the reinforcing member 12 is moved, as shown in
Thereafter, the reinforcing member 12 is heated by the heater 16. The heater 16 is composed of the heater wire 16a and the heater platform 16b. As the heater platform 16, what has a flat heating surface and a simple and general shape can be used. The reinforcing member 12 is placed, for example, so that the tensile strength body 14 is opposed to the heater platform 16b. The tube-shaped heat-fusible adhesive members 15 are uniformly heated through the tensile strength body 14. By heating by the heater 16, the tube-shaped heat-fusible adhesive members 15 are melted, the melted adhesive members 15 infill gaps in the heat-shrinkable tube 13, and the heat-shrinkable tube 13 shrinks in a radial direction thereby to push out the inner air to the outside.
The melted tube-shaped heat-fusible adhesive member 15 covers the glass fiber portion 10 of each coated optical fiber 11, the fusion-splicing portion 10a and the end portion of the not-removed fiber coating so as to include them, and protects them so that they do not come into direct contact with the fusion-spliced portions of other coated optical fibers. Further, simultaneously, the tube-shaped heat-fusible adhesive member 15 adheres to the inner surface of the heat-shrinkable tube 13 of which the diameter has been narrowed and also to the tensile strength member 14. After heating has been performed by the heater 16 for the predetermined time, a heating power source is turned off to cool the reinforcing member naturally or forcedly, and then the melted adhesive members are solidified. Thus, the fusion-splicing portion 10a in the heat-shrinkable tube 13 having the narrowed diameter, the vicinity of the fusion-splicing portion 10a, and the tensile strength body 14 are integrated thereby to be protected and reinforced.
By using the thus configured reinforcing member, without the tube-shaped heat-fusible adhesive members being arranged with the tensile strength body between as shown in
While the embodiment of the invention has been described in detail, it would be apparent to those skilled in the art that various changes and modifications may be made therein without departing from the spirit and scope of the invention. The present application is based on Japanese Patent Applications JP-2009-267747, filed on Nov. 25, 2009 and JP-2010-11879, filed on Jan. 22, 2010, the entire contents of which are hereby incorporated by reference.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2009-267747 | Nov 2009 | JP | national |
| 2010-011879 | Jan 2010 | JP | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP2010/070978 | 11/25/2010 | WO | 00 | 5/24/2012 |
