JP5460347B2 - Reinforcing sleeve for optical fiber - Google Patents

Description

  The present invention relates to an optical fiber reinforcing sleeve, and more particularly to an optical fiber reinforcing sleeve that reinforces a fusion spliced portion between coated optical fibers.

  Conventionally, when connecting optical fibers, the coating of the core wire is removed to expose the optical fiber, and the exposed ends of the optical fiber are abutted and fused. For this reason, in the fusion-bonded optical fiber, the mechanical strength of the exposed portion of the optical fiber is lowered. Therefore, when splicing an optical fiber, a long tensile body made of a metal material or the like is disposed along the longitudinal direction of the exposed portion of the optical fiber, and a heat-shrinkable tube is installed so as to cover the inner tube and the tensile body. The exposed portion of the optical fiber including the fusion splicing portion is encapsulated and reinforced by melting the inner tube and heat shrinking the heat shrinkable tube.

  FIG. 8 is a view showing the configuration of a conventional optical fiber reinforcing sleeve, FIG. 9 is a view for explaining a reinforcing procedure of the fusion splicing portion in FIG. 8, and (a) shows a state before heating. , (B) shows the state after heating.

  As shown in FIGS. 8 and 9, the optical fiber reinforcing sleeve 80 includes a heat-shrinkable outer tube 81 (length L2), a heat-meltable inner tube 82 (length L1: L1 <L2), And an elongated tensile body 83 disposed in the vicinity of the outer peripheral surface of the inner tube along the longitudinal direction of the inner tube 82.

  When reinforcing an optical fiber using the reinforcing sleeve 80, first, the reinforcing sleeve 80 is passed through one of the two optical fiber cords 91A and 91B, and the optical fiber 92A is inserted from the optical fiber core of the one optical fiber cord 91A. And the optical fiber 92B is exposed from the optical fiber core of the other optical fiber cord 91B. Next, the optical fiber 92A and the optical fiber 92B are fused and connected by an optical fiber fusion splicer (not shown).

  Next, a reinforcing sleeve 80 passed through one of the two optical fiber cords is placed so as to cover the fusion spliced portion between the optical fibers 92A and 92B (FIG. 9A). At this time, the inner tube 82 is disposed so as to cover the fusion splicing portion and the exposed portions of the optical fibers 92A and 92B. And the outer tube 81 is arrange | positioned so that the edge part of the inner tube 82 and the two optical fiber cords 91A and 91B may be covered. When the reinforcing sleeve 80 is heated in this state, the outer tube 81 is thermally contracted, and the inner tube 82 is thermally melted inside the outer tube 81, whereby the exposed portions of the optical fibers 92A and 92B including the fusion splicing portion. Is encapsulated (FIG. 9B) (see, for example, Patent Document 1).

JP 2008-332266 A

  However, in the case of a reinforcing sleeve for an optical fiber, normally, air remains in the reinforcing sleeve during heating, and bubbles may be generated in the reinforcing sleeve. If bubbles exist inside the reinforcing sleeve after heating, there is a problem in that the bubbles expand and contract as the environment changes, adversely affecting the optical fiber and causing light loss.

  An object of the present invention is to provide an optical fiber reinforcing sleeve capable of improving the mechanical strength of a fusion splicing portion of an optical fiber and preventing the generation of bubbles to prevent a decrease in optical loss. .

In order to achieve the above object, an optical fiber reinforcing sleeve according to the present invention includes an optical fiber coated wire end portion, and a fusion splicing portion formed by fusing optical fibers derived from the optical fiber coated wire end portion. Is inserted so as to cover the inner tube and the strength member, and a tensile strength member disposed in the vicinity of the outer peripheral surface of the inner tube along the longitudinal direction of the inner tube. and a heat-shrinkable outer tube, the inner tube is to have at least one hole provided in the vicinity of the optical fiber covered wire ends, wherein at least one of the holes, upon melting the inner tube through the holes encourages the discharge to the outside of the air in the inner tube, and wherein the hole der Rukoto for preventing the generation of bubbles.

  Preferably, the at least one hole is provided in the vicinity of the end portion of the optical fiber covered wire, and is provided outside the end surface of the end portion of the optical fiber covered wire with respect to the axial direction of the inner tube.

  Preferably, the hole extends substantially perpendicular to the longitudinal direction of the inner tube.

Preferably, the inner tube is disposed in an upper portion of the outer tube, the strength member is disposed in a lower portion of the outer tube, and the hole is provided in an upper portion of the inner tube.
In order to achieve the above object, an optical fiber reinforcing sleeve according to the present invention includes an optical fiber coated wire end portion and a fusion splicing by fusion of optical fibers derived from the optical fiber coated wire end portion. A heat-meltable inner tube that is inserted through the portion, a tensile body disposed in the vicinity of the outer peripheral surface of the inner tube along the longitudinal direction of the inner tube, and a cover that covers the inner tube and the tensile body A heat-shrinkable outer tube, and the inner tube has at least one slit provided in the vicinity of an end portion of the optical fiber-coated wire, and the at least one slit melts the inner tube. In this case, it is a slit for promoting the discharge of the air in the inner tube to the outside through the slit and preventing the generation of bubbles.

According to the present invention, the end portion of the optical fiber covered wire and the fusion spliced portion by fusion of the optical fibers led out from the end portion of the optical fiber covered wire are inserted into the inner tube, and the strength member is connected to the inner tube. Since it is arranged in the vicinity of the outer peripheral surface of the inner tube along the longitudinal direction, the inner tube is melted to weld the fusion spliced portion and the tensile strength body, thereby improving the bending strength and tensile strength of the spliced joint portion. be able to. Since at least one hole is provided in the vicinity of the end of the optical fiber covered wire, when the inner tube is melted, air is expelled from the tube, and generation of bubbles can be prevented. Therefore, the mechanical strength of the fusion splicing portion can be improved, and the generation of bubbles in the reinforcing sleeve can be prevented, thereby preventing the light loss from decreasing.
Further, according to the present invention, the end portion of the optical fiber covered wire and the fusion spliced portion by fusion of the optical fibers led out from the end portion of the optical fiber covered wire are inserted into the inner tube so Since it is arranged in the vicinity of the outer peripheral surface of the inner tube along the longitudinal direction of the tube, the inner tube is melted and the fusion splicing portion and the tensile strength body are welded, whereby the bending strength and tensile strength of the fusion splicing portion are increased. Can be improved. Since at least one slit is provided in the vicinity of the end portion of the optical fiber-coated wire, when the inner tube is melted, the discharge of air from the tube is promoted, and the generation of bubbles can be prevented. Therefore, the mechanical strength of the fusion splicing portion can be improved, and the generation of bubbles in the reinforcing sleeve can be prevented, thereby preventing the light loss from decreasing.

It is a perspective view which shows roughly the structure of the reinforcement sleeve for optical fibers which concerns on the 1st Embodiment of this invention. It is sectional drawing which follows the line II of FIG. It is sectional drawing which follows the line II-II of FIG. It is a side view which shows the structure of the internal tube in FIG. It is a figure explaining the reinforcement procedure of the fusion splicing part using the reinforcement sleeve for optical fibers of FIG. 1, (a) shows the state before a heating, (c) shows the state after a heating. It is a perspective view which shows roughly the structure of the reinforcement sleeve for optical fibers which concerns on the 2nd Embodiment of this invention. It is sectional drawing which follows the line III-III of FIG. It is a figure which shows the structure of the reinforcement sleeve for conventional optical fibers. It is a figure explaining the reinforcement procedure of the fusion splicing part in FIG. 8, (a) shows the state before a heating, (b) shows the state after a heating.

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

  FIG. 1 is a perspective view schematically showing a configuration of a reinforcing sleeve for an optical fiber according to an embodiment of the present invention, FIG. 2 is a cross-sectional view taken along line I-I in FIG. 1, and FIG. 1 is a cross-sectional view taken along line II-II of FIG. In the present embodiment, a drop cable will be described as an example of the optical fiber duplex.

  1 to 3, an optical fiber reinforcing sleeve 1 has a thermally fusible inner portion through which a drop cable end portion and a fusion spliced portion by fusion of optical fibers led out from the drop cable end portion are inserted. A tube 11, a long strength member 12 disposed in the vicinity of the outer peripheral surface of the inner tube along the longitudinal direction of the inner tube 11, and a heat shrinkability disposed so as to cover the inner tube 11 and the strength member 12. External tube 13. The inner tube 11 is arranged at the upper part in the outer tube 13 with respect to the mounting surface serving as a heating table in a fusion sleeve fusion machine (not shown), and the tensile body 12 is arranged at the lower part in the outer tube 13. Is done.

  The inner tube 11 has a length, an outer diameter, and an inner diameter of, for example, 60 mm, 6 mm, and 3 mm. The inner tube 11 is formed from a hot melt resin, for example, a hot melt resin. Examples of the hot melt resin include an ethylene vinyl acetate copolymer (EVA) system, a polyolefin (PP) system, a polyamide (PA) system, and a synthetic resin. Rubber (SR) or the like is used. The length of the inner tube 11 is set to a value that can cover the fusion spliced portion of the optical fiber and the drop cable ends located on both sides thereof (FIG. 4). Further, the inner tube 11 has slits 11 a and 11 b (holes) provided near the end of the drop cable and provided on the inner side of the end surface of the drop cable in the axial direction of the inner tube 11.

  The strength member 12 has a substantially circular cross section, and its length and outer diameter are, for example, 60 mm and φ1.0. The strength member 12 is made of steel, glass FRP, or aramid fiber FRP. Since the strength member 12 is included in the reinforcing sleeve 1, the fusion splicing portion is protected from the acting bending force and pulling force.

  The outer tube 13 has an outer diameter and an inner diameter of 6 mm and 5 mm, respectively, and is formed from a resin such as polyvinyl chloride resin, fluororesin, polystyrene resin, or polyolefin resin. The outer tube 13 is preferably transparent so that the fusion spliced portion can be observed from the outside. The outer tube 13 serves to weld the optical fiber and the strength member 12 when contracted by heating, and the strength member 12 imparts strength in the bending direction and the tension direction to the fusion spliced portion. For this reason, a resin whose shrinkage start temperature is the same as the melting temperature of the inner tube 11 or higher than the melting temperature is used for the outer tube 13.

  In general, a drop cable has a configuration in which a cable main body having a sheath applied to an optical fiber core wire and a support wire having a sheath applied to a support wire are integrated by a connecting portion. Since the drop cable reinforcement work is normally performed on the cable main body part from which the support line part has been peeled off, the cable main body part is referred to as a “drop cable” in the present embodiment.

  FIG. 4 is a side view showing the configuration of the inner tube 11 in FIG.

  As shown in FIG. 4, in the inner tube 11, drop cable portions 41A and 41B through which the drop cable ends 30A and 30B are inserted and optical fibers 30a and 30b led out from the drop cable ends 30A and 30B are inserted. And a portion 42 for optical fiber. Slits 11a and 11b are provided in the vicinity of both ends of the optical fiber portion 42. The slits 11a and 11b extend substantially at right angles to the longitudinal direction of the inner tube 11 and are formed under the inner tube. On the side.

  The distance between the drop cable end portions 30A and 30B in a state where the optical fibers 30a and 30b are fusion spliced is a specific value determined by the fusion splicer used, and is, for example, 40 mm. In the present embodiment, each of the slits 11a and 11b is formed at a predetermined distance, for example, 11 mm from the end surface of the inner tube 11 toward the inside. Therefore, when the center position of the inner tube 11 is matched with the fusion splicing portion, the distance between the drop cable end portions 30A and 30B and the slits 11a and 11b is 1 mm.

  Here, if the drop cable reinforcing sleeve is heated to melt the inner tube, air that has not escaped from the reinforcing sleeve, particularly the inner tube, may remain as bubbles. The bubbles are mainly generated near the drop cable end and inside the drop cable end surface with respect to the axial direction of the inner tube, and further below the optical fiber led out from the drop cable.

  Therefore, in the present embodiment, the slit 11a (11b) is provided in the vicinity of the drop cable end 30A (30B). Thereby, discharge | emission of the air from the inside of the internal tube 11 is promoted, and generation | occurrence | production of a bubble is prevented. Further, by providing the slits 11a and 11b on the inner side of the end surface of the drop cable end 30A (30B) in the axial direction of the inner tube 11 and at the lower part of the inner tube 11, the discharge of air is further promoted, and bubbles are generated. It is surely prevented. Moreover, since the slits 11a and 11b are not formed over the entire inner tube 11 and are formed only in the vicinity of the end portion of the drop cable, it is possible to reduce the work man-hour when forming the slit in the inner tube 11.

  Normally, when the outer diameter of the optical fiber core wire is increased, the outer shape of the drop cable (sheath) covering the optical fiber core wire is increased, and the inner diameter of the inner tube is determined according to the outer shape of the drop cable. Therefore, the larger the difference between the outer size of the drop cable to be reinforced and the outer diameter of the optical fiber (or the difference in cross-sectional area), the greater the amount of air that should be discharged from the inside of the inner tube. In the present embodiment, the outer diameter of the optical fiber is, for example, 125 μm, and the outer diameters of the optical fiber core wires (element wires) are, for example, 250 μm, 400 μm, 500 μm, and 900 μm. When a drop cable having such an outer diameter optical fiber and an optical fiber core wire is reinforced with the optical fiber reinforcing sleeve of the present invention, air is urged to be discharged from the inner tube through the slit, and bubbles are surely generated. To be prevented.

  Since the inner tube 11 has drop cable portions 41A and 41B through which the drop cable end portions 30A and 30B are inserted, when the inner tube melts, the outer peripheral surface of the drop cable end portions 30A and 30B and the outer tube 13 inner peripheral surfaces are welded and joined. Thereby, it is possible to prevent air and moisture from entering between the drop cable ends 30A and 30B and the external tube 13, and it is possible to prevent the occurrence of light loss after the reinforcement work.

  FIGS. 5A and 5B are diagrams for explaining the reinforcement processing of the fusion spliced portion using the optical fiber reinforcing sleeve 1 of FIG. 1, wherein FIG. 5A shows a state before heating, and FIG. 5B shows a state after heating.

  In FIG. 5 (a), before the two optical fibers 30a and 30b are fused and connected, one drop cable from which the sheath such as the sheath is removed to expose the optical fiber 30b is connected to the inner tube. 11 and the drop cable reinforcing sleeve 1 is attached.

  Next, the end portions of the optical fibers 41a and 41b are brought into contact with each other, and the two optical fibers 30a and 30b are fused and connected. Thereafter, the drop cable reinforcing sleeve 1 is moved to the fusion splicing portion Ps, and the fusion splicing portion Ps and the drop cable end portions 30A and 30B are covered with the reinforcing sleeve 1.

  Subsequently, the drop cable reinforcing sleeve 1 is heated from below and from the side using a reinforcing sleeve fusion machine (not shown). The heating temperature of the drop cable reinforcing sleeve 1 is set to have a maximum value at the center position in the longitudinal direction and to decrease toward both sides from the center position. When the heating temperature is set in this way, the outer tube 13 contracts in order from the center position toward both sides, and the inner tube 11 melts in order from the center position toward both sides. At this time, the air inside the external tube 13 is pushed out to both sides, and is discharged to the outside from each end of the external tube. Furthermore, the air inside the inner tube 11 is pushed out to both sides and is discharged to the outside through the slits 11a and 11b of the inner tube 11 from each end of the inner tube. Therefore, the generation | occurrence | production of the bubble in the reinforcement sleeve 1 for drop cables is prevented. By the above reinforcing procedure, the outer tube 13 is thermally contracted, and the inner tube 11 is welded to the optical fibers 30a and 30b and the strength member 12, and the bending connection and the pulling direction in the fusion splicing portion Ps and the optical fibers 30a and 30b Strength is imparted (FIG. 5B).

  As described above, according to the present embodiment, the inner tube 11 has the fusion-bonded portion Ps formed by the fusion of the drop cable end portions 30A and 30B and the optical fibers 30a and 30b led out from the drop cable end portions. Is inserted in the vicinity of the outer peripheral surface of the internal tube along the longitudinal direction of the internal tube 11, so that the internal tube 11 is melted and the fusion splicing portion Ps and the tensile body 12 are welded. Thereby, the bending strength and the tensile strength of the fusion splicing part Ps can be improved. And since slit 11a, 11b is each provided in drop cable edge part 30A, 30B vicinity, discharge | emission of the air from the inside of the internal tube 11 is promoted, and generation | occurrence | production of a bubble can be prevented. Therefore, the mechanical strength of the fusion splicing portion Ps can be improved, and the generation of bubbles in the reinforcing sleeve 1 can be prevented, thereby preventing the light loss from decreasing.

  In the present embodiment, the slits 11a and 11b are provided one by one in the vicinity of the drop cable end portions 30A and 30B, respectively. However, the present invention is not limited to this, and at least one slit may be provided at the drop cable end portion. Good. Further, at least one hole having a shape other than the slit may be provided at the end of the drop cable.

  Further, in the present embodiment, the heating temperature of the drop cable reinforcing sleeve 1 is set to have a maximum value at the center position in the longitudinal direction and to decrease from the center position toward both sides, but is not limited thereto. . The heating timing may be controlled so that the center position is first heated under the condition of a constant heating temperature and then heated sequentially from the center position toward both sides.

  FIG. 6 is a perspective view schematically showing the configuration of an optical fiber reinforcing sleeve according to the second embodiment of the present invention, and FIG. 7 is a cross-sectional view taken along line III-III in FIG. In the present embodiment, a tape cord having a plurality of optical fiber core wires as an optical fiber coated wire will be described as an example.

  As shown in FIGS. 6 and 7, the optical fiber reinforcing sleeve 60 is formed by thermal melting through which a tape cord end portion and a fusion splicing portion by fusion of optical fibers led out from the tape cord end portion are inserted. Internal tube 61, a long tensile strength body 62 disposed in the vicinity of the outer peripheral surface of the internal tube along the longitudinal direction of the internal tube 61, and the internal tube 61 and the tensile strength body 62. A heat-shrinkable outer tube 63. The inner tube 61 is disposed in the upper part of the outer tube 63 with respect to the mounting surface serving as a heating table in the unillustrated reinforcing sleeve fusion machine, and the tensile body 62 is disposed in the lower part of the outer tube 63. Is done.

  The tape cord 70 has a configuration in which a plurality of optical fiber cores 71 are arranged in a plane and are integrally covered with a tape resin. In the present embodiment, a tape cord in which four optical fiber cores are arranged in a plane is illustrated, but the present invention is not limited to this.

  The strength member 62 has a substantially semicircular cross section, and its length is substantially the same as that of the outer tube 61. The strength member 62 is formed from, for example, quartz or ceramic. The tensile body 62 has a flat portion on the side surface, and is disposed so that the flat portion faces the tape core wire side.

  The inner tube 61 has slits 61 a and 61 b (holes) provided near the end of the tape cord and provided outside the end surface of the end of the tape cord in the axial direction of the inner tube 61. The slits 61a and 61b extend substantially at right angles to the longitudinal direction of the inner tube 61 and are provided on the upper side of the inner tube.

  Here, if the tape cord reinforcing sleeve is heated to melt the inner tube, the air that has not escaped from the reinforcing sleeve may remain as bubbles. This bubble is mainly generated near the end of the tape cord and outside the end surface of the end of the tape cord with respect to the axial direction of the inner tube, and further above the end of the tape cord.

  Therefore, in this embodiment, the slit 61a (61b) is provided in the vicinity of the tape cord end portion 70A (70B) (FIG. 7). Thereby, the discharge of air from the inner tube 61 is promoted, and the generation of bubbles is prevented. Further, by providing the slits 61a and 61b outside the end surface of the tape cord end portion 70A (70B) in the axial direction of the inner tube 61 and on the upper portion of the inner tube 61, the discharge of air is further promoted, and bubbles are generated. It is surely prevented. Further, since the slits 61a and 61b are not formed over the entire inner tube 61 but are formed only in the vicinity of the end portion of the tape cord, it is possible to reduce the work man-hour when forming the slit in the inner tube 61.

  According to the present embodiment, the inner tube 61 is inserted with the tape cord end portions 70A and 70B and the fusion splicing portion Ps ′ by fusion of the optical fibers 70a and 70b led out from the tape cord end portions. Since the tensile body 62 is disposed in the vicinity of the outer peripheral surface of the internal tube along the longitudinal direction of the internal tube 61, the internal tube 61 is melted and the fusion splicing portion Ps and the tensile body 62 are welded. The bending strength and tensile strength of the landing connection portion Ps ′ can be improved. Since the slits 61a and 61b are provided in the vicinity of the tape cord end portions 70A and 70B, discharge of air from the inside of the internal tube 61 is promoted, and generation of bubbles can be prevented. Therefore, the mechanical strength of the fusion splicing part Ps ′ can be improved, and the generation of bubbles in the reinforcing sleeve 60 can be prevented, thereby preventing a reduction in light loss.

  In the present embodiment, the slits 61a and 61b are provided one by one at the tape cord end portions 70A and 70B, respectively, but the present invention is not limited to this, and at least one slit may be provided at the tape cord end portion. . Further, at least one hole having a shape other than the slit may be provided at the end of the tape cord.

  In the above-described embodiment, the inner tubes 11 and 61 are made of a colorless and transparent resin, but are not limited thereto, and may be made of a colored and transparent resin containing a predetermined color, for example, a yellow dye. As a result, the optical fiber can be easily visually recognized from the outside, and even if minute bubbles are generated in the optical fiber reinforcing sleeve after the heat treatment, the presence of the bubbles can be easily visually confirmed. Occurrence can be reliably prevented.

  In the above-described embodiment, the drop cable and the tape cord are exemplified as the optical fiber coated wires. However, the present invention is not limited to this, and an optical fiber such as an indoor cable, a single-core cord, a two-core cord, or an in-home optical fiber cord The reinforcing sleeve of the present invention may be applied to the covered wire.

DESCRIPTION OF SYMBOLS 1,60 Reinforcement sleeve 11, 61 Inner tube 11a, 11b, 61a, 61b Slit 12, 62 Strength member 13, 63 Outer tube 30a, 30b Optical fiber 30A, 30B Drop cable end part 41A, 41B Drop cable part 42 Optical fiber Site 70 Tape cord 70A, 70B Tape cord end 71 Optical fiber core wire

Claims (5)

A thermally fusible inner tube through which an optical fiber coated wire end portion and a fusion splicing portion by fusion of optical fibers led out from the optical fiber coated wire end portion are inserted;
A tensile body disposed in the vicinity of the outer peripheral surface of the inner tube along the longitudinal direction of the inner tube;
A heat-shrinkable outer tube arranged to cover the inner tube and the tensile body,
The inner tube has at least one hole provided in the vicinity of the end portion of the optical fiber coated wire,
The at least one hole is a hole for facilitating discharge of air in the inner tube through the hole when the inner tube is melted to prevent generation of bubbles. Reinforcing sleeve for optical fiber.   The at least one hole is provided in the vicinity of the end portion of the optical fiber covered wire and is provided outside the end surface of the end portion of the optical fiber covered wire with respect to the axial direction of the inner tube. Reinforcing sleeve for optical fiber.   3. The optical fiber reinforcing sleeve according to claim 1, wherein the hole extends substantially perpendicular to the longitudinal direction of the inner tube. The inner tube is disposed at an upper portion in the outer tube, and the tensile body is disposed at a lower portion in the outer tube,
4. The optical fiber reinforcing sleeve according to claim 1, wherein the hole is provided in an upper portion of the inner tube. 5. A thermally fusible inner tube through which an optical fiber coated wire end portion and a fusion splicing portion by fusion of optical fibers led out from the optical fiber coated wire end portion are inserted;
A tensile body disposed in the vicinity of the outer peripheral surface of the inner tube along the longitudinal direction of the inner tube;
A heat-shrinkable outer tube arranged to cover the inner tube and the tensile body,
The inner tube has at least one slit provided in the vicinity of the end portion of the optical fiber coated wire,
The at least one slit is a slit for preventing the generation of bubbles by facilitating the discharge of the air in the inner tube through the slit when the inner tube is melted. Reinforcing sleeve for optical fiber.

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