JP3876273B2 - Optical fiber retainer - Google Patents

Description

  The present invention relates to a holding device for an optical fiber core end of an optical fiber cable that uses a loose tube type unit as a fiber unit or has a configuration conforming to the loose tube type unit, and particularly to a submarine cable to which a greater external tension is applied. And suitable.

  Developed as an optical fiber unit built in the center of a submarine optical cable, with the aim of inserting more optical fiber cores to meet the increasing demand for communication lines instead of the tight-type optical fiber unit that has been used in the past. Loose tube type units tend to be used.

The difference between the tight type unit and the loose tube type unit will be described with reference to FIG.
As shown in a schematic cross section in FIG. 6 (a), the tight optical fiber unit 80 is provided with a central strength member 80b such as a steel wire at the center of the optical fiber unit, and several light beams are provided at the periphery. The fiber core wire 1a is filled and held via a urethane acrylate resin 80c, and the outer periphery is formed as a coating layer of urethane acrylate resin or the like that is hard to some extent.
Strictly speaking, optical fibers are classified into optical fiber strands with a primary coating on the surfaces of a vitreous core and cladding, and optical fiber cores with a secondary coating on the primary coating. Hereinafter, both the strands and the cores will be referred to as optical fibers without distinction.

In the loose tube type unit 1 shown in FIG. 2B, a plastic such as polybutylene terephthalate (PBT) or polypropylene (PP) is formed by passing a plurality of optical fibers 1a through a jelly-like filler (compound) 1c. It is inserted through the loose tube 1d formed by the above.
In addition, as shown to the enlarged view E of the figure (c), the optical fiber 1a can also be supplied in the form of the optical fiber tape core wire 1e which restrained several optical fibers in tape shape beforehand.

Next, a structural example of a submarine optical cable using a loose tube type unit will be described with reference to a perspective view of FIG. 7 and a cross-sectional view cut at right angles to the axis of the cable of FIG. In these figures, 1 is a loose tube type optical fiber unit, 2 is a pressure-resistant layer for protecting the loose tube type unit 1 from water pressure, and in this figure, the section is made of a metal such as a fan-shaped iron. Three pieces 2a are used in combination along the length. A compound 7 having adhesiveness or adhesiveness is filled between the loose tube 1 d and the inner surface of the pressure-resistant layer 2, and the loose tube 1 d is constrained through the compound 7.
On the outer periphery of the pressure-resistant layer 2, there is a tensile body layer 3 formed by twisting a plurality of steel wires 3a so as to sufficiently cope with the tensile force applied to the cable. A compound 8 is intermittently filled in the longitudinal direction in a space defined by the outer peripheral surface of the pressure-resistant layer 2, the inner peripheral surface of the metal tube layer 4, and the outer peripheral surface of the tensile strength wire 3a.

The tensile strength layer 3, which is one layer in FIG. 7, is mainly configured by twisting steel wires so as to sufficiently cope with the tensile force applied to the cable.
The tensile strength body layer 3 has a single-layer or multi-layer structure, applies a tensile strength sufficient to withstand the load when the cable is laid, and protects the cable against a failure.
4 is a metal tube layer that maintains the tightness and airtightness of the tensile body layer 3 and serves as a power supply path to the repeater. Usually, a metal tape made of copper, aluminum, or the like is vertically welded to reduce the diameter to form a tube shape. Formed.
Reference numerals 5 and 6 denote insulating layers (sheaths) formed of polyethylene or the like for the purpose of insulation from seawater and mechanical protection.

A cable having a configuration different from the above is also used for the tensile strength layer. In the example shown in the perspective view of FIG. 9 and the cross-sectional view of FIG. 10, the structure of the pressure-resistant layer is changed. That is, the pressure-resistant layer is constructed so that a pressure-resistant shell is realized on the outer periphery of the loose tube type unit 1 by the competition of the tensile strength lines that are twisted into the two layers composed of the inner-strength tensile strength line 3a and the outer-strength tensile strength line 3b.
A compound 7 having adhesiveness or adhesiveness is filled between the outer peripheral surface of the loose tube type unit 1 and the curved surface on the side where the tensile strength line 3a faces the loose tube type unit 1, and through this compound 7, A pressure-resistant shell (a shell whose diameter is substantially the inner surface of the tensile strength wire 3a) restrains the loose tube 1d.
The metal tube layer 4 and the insulating layers 5 and 6 outside the metal tube layer 4 have the same configuration as that shown in FIGS.

  Since such a submarine optical cable is normally laid between continents or between continents and islands, a long cable is laid on the seabed via a repeater that relays transmitted signals. It is necessary to connect cables and repeaters at multiple locations or between long cables. This type of submarine optical cable can be used with optical fiber 1a and metal tubes so that they can sufficiently withstand installation and collection in the deep sea. The cables 4 are optically and electrically connected by firmly fixing so-called strength members such as the mutual connection between the layers 4, the divided pieces constituting the pressure-resistant layer 2 and the tensile wires 3 a and 3 b constituting the strength layer 3. And it must be mechanically connected (so-called retaining).

As a loose tube type optical fiber holding device, the optical fiber holding position is formed in a tape shape with an adhesive, and this tape optical fiber is inserted into the through hole of the shrinkable tube and heated to integrate. In some cases, the shrinkable tube is housed in a fixing material, and the fixing material is fixed to hold the optical fiber. (For example, refer to Patent Document 1).
What was described in Patent Document 1 was to hold the optical fiber by the side pressure of the shrinkable tube and the frictional force of the adhesive.

The submarine optical cable is connected via a terminal connection device. In the terminal connection device, the connecting portion of the optical fiber core wire is housed in a pressure-resistant cylinder so as to function under high pressure on the seabed. The pressure-resistant cylinder not only withstands the high pressure of seawater but also has the strength to withstand the tension of the cables on both sides, so that the tension of the submarine optical cable is transmitted to each other via the pressure-resistant cylinder in the terminal connection device.
Therefore, in order to mechanically connect the submarine optical cable to these terminal connection devices, it is retained by fixing the terminals such as the divided pieces 2a and the tensile strength wires 3a to the pressure-resistant cylinder or a member fixed thereto.

In the case of submarine cables, it is assumed that the maximum tension applied to the cables is approximately the same as the breaking load of the components of each cable, and it is desirable to retain all the components. In addition, a case where each component member is pulled into the cable due to tension is likely to occur, and the optical fiber itself needs to be firmly fastened to the fixed portion of the terminal connection device.
In Japanese Patent Application No. 2002-63172 filed earlier by the present applicant, a loose tube is wound around a drum-shaped retaining disk shown in FIG. 11 (a), and an internal jelly-like filler is inserted through the loose tube. And a method of simultaneously holding the optical fiber core wires and a method of holding the optical fiber core wires in the loose tube alone using the adhesive shown in FIG.

FIG. 11A is a cross-sectional view of a part of a joint box (JB) 20 which is a kind of terminal connection device, cut along a plane including the axis of the submarine optical cable.
The surface of the pressure cylinder 28 that is the main body of the JB 20 is covered with an insulator 27. The pressure cylinder 28 is a high-strength metal cylinder, and the anchor disk 11 is inserted into a hole in the center of the end plate formed at both ends of the cylinder.
The submarine optical cable 50 is inserted into the hole at the center of the insulator 27 from the right side. The submarine optical cable 50 is, for example, a type having a loose tube type unit shown in FIG.
The metal tape layer 4 and the insulating layers 5 and 6 of the cable 50 are removed, and the divided pieces 2a constituting the pressure-resistant layer 2 and the tensile wires 3a constituting the tensile body layer 3 are spread over the taper hole in the center of the anchor disk 11. The taper pin 13 is press-fitted and clamped. The taper pin 13 is pressed by a clamp nut 15 via a flange 14 for positioning.
The tension applied to the cable 50 is transmitted from the divided piece 2a and the tensile strength wire 3a to the pressure-resistant cylinder 28 via the anchor disk 11 and the taper pin 13, and is transmitted to a cable (not shown) connected to the left end.

In FIG. 11A, reference numeral 60 denotes an optical fiber holding device that holds the loose tube and the optical fiber at the same time. The loose tube type unit 1 of the cable 50 passes through the through holes of the taper pin 13, the flange 14, and the clamp nut 15, and is guided by the winding guide 16 to reach the pressure-resistant cylinder 28. A substantially cylindrical retaining disk 61 is fixed to a base plate 62 fixed to the pressure resistant cylinder 28 in the pressure resistant cylinder, and the loose tube type unit 1 is wound around the outer peripheral cylindrical surface of the retaining disk 61 a plurality of times. After that, the end is fixed to the base plate 62 by the terminal fixture 63.
The force acting on the loose tube type unit 1 from the terminal fixture 63 is expanded by the frictional force with the winding portion of the loose tube type unit 1 wound around the retaining disk, and the loose tube type unit 1 is retained. The inner optical fiber 1a is also retained by frictional force with the filled jelly-like filler 1c.

On the other hand, the optical fiber holding device 70 shown in FIG. 11B is a holding device using an adhesive, and is disposed almost at the same position as the optical fiber holding device 60 of FIG. . The method of retaining the divided pieces 2a and the tensile wires 3a of the cable 50 is processed in the same manner as in FIG. 11A, and the loose tube type unit 1 is linearly guided into the pressure-resistant cylinder 28.
The loose tube 1 d of the loose tube type unit 1 is secured to the loose tube bonding tool 72 by bonding or the like.
Next, the loose tube 1d is removed from the loose tube type unit 1, the optical fiber 1a is taken out, the jelly-like filler 1c is wiped off, aligned with the groove of the optical fiber bonding tool 73, and adhered to the groove with an adhesive. An epoxy resin or a UV curable resin is used for the adhesive.

By the way, in order to reduce the components of the submarine optical cable, proposals have been made to substitute the function of the loose tube on the inner peripheral surface of the pressure-resistant shell.
For example, FIG. 12 shows, as a perspective view, the configuration of two types of submarine optical cables that do not have a loose tube but have an optical fiber accommodation structure equivalent to a loose tube type unit in terms of performance.
As shown in FIG. 12, in the first structure, a divided pressure piece 2 having a fan-shaped cross section is combined to form a cylindrical pressure-resistant layer 2, and a compound 7 is densely applied to a gap between the divided pieces 2a. An optical fiber core wire is inserted into the internal space, and the gap is tightly filled with a jelly-like filler 1c. The loose tube constituting the loose tube type unit is substituted by the pressure-resistant layer 2 and the compound 7, and the loose tube itself does not exist.

  The example shown in FIG. 12 lacks the loose tube, but has a space corresponding to the inner peripheral surface of the loose tube, is inserted with the optical fiber 1a, and is filled with a jelly-like filler 1c. The holding method is the same function as the loose tube type unit.

JP 2001-108840 A

  Since the terminal connection device used for connecting the submarine cable needs to be small in consideration of mechanical characteristics, handling, etc., the cable tension member retaining device is also required to be small. In optical cables, it is necessary to handle the connected optical fiber cores so that excessive mechanical tension is not applied to them, and an extra-length storage body that accommodates the extra length of the optical fiber core wires is arranged in the pressure-resistant cylinder. The cable retaining device is also required to be small.

  The diameter of the retaining disk used in the conventional example is limited by the allowable radius of curvature that does not impair the transmission characteristics of the optical fiber core. In addition, when the optical fiber core wire is bonded linearly with an adhesive, a considerable length of the bonded portion is required to securely hold the optical fiber core wire. Moreover, since the retaining disk and the optical fiber core wire bonding tool are housed in the pressure-resistant cylinder in terms of configuration, there is a problem that the momentum pressure-resistant cylinder becomes large.

Furthermore, in the case of bonding, a normal adhesive requires a curing time of 8 hours or longer if complete bonding is expected.
In any of the conventional methods, there are problems that increase costs, such as an increase in work period, an increase in equipment cost, and a high cost of materials.

In addition, it is obvious that a submarine optical cable configured to produce the effect of a loose tube type unit without using a loose tube cannot use a method similar to that shown in FIG. is there.
Also. The optical fiber retaining position is formed in a tape shape with an adhesive, and the tape-shaped optical fiber is inserted into the through hole of the shrinkable tube and integrated by heating. When pulling the fiber, it is necessary to avoid excessive slack and tension of the fiber because the contraction tube into which the optical fiber is inserted contracts at the position assumed to be attached to the fixing material. It is difficult to position, it takes time to cure the adhesive because the optical fiber is formed into a tape with an adhesive, and the lateral pressure is fixed by mechanical methods such as sandwiching the shrinkable tube with the fixing when storing it in the fixing As a result, there is a problem that the transmission characteristics of the optical fiber deteriorate.

  The present invention aims to reduce the size and work time of the above-described optical fiber retaining device, and further provides an optical fiber retaining device that can be applied to an optical cable having a simple structure without a loose tube.

  In order to solve the above problems, the present invention provides an optical cable having a loose tube type unit in which a single core or a plurality of optical fibers are inserted into a cylindrical tube made of metal or resin together with a jelly-like filler. An optical fiber holding device that is installed inside a terminal connection device to be connected and holds one or more optical fibers inserted through the optical cable, a tubular hot melt adhesive having a hollow portion; A tube-shaped heat-shrinkable tube having a hollow portion and a rod-shaped support, and the hot-melt adhesive is inserted into the hollow portion of the heat-shrinkable tube, and one end of the rod-shaped support is The hot melt adhesive is disposed in the hollow portion, the solid portion, or the outer peripheral portion, and at least one of the optical fibers is placed in the hot melt adhesive. The hot-melt adhesive is melted and the heat-shrinkable tube is shrunk so as to be integrated with one end of the rod-shaped support and the optical fiber so that the axis of the optical cable is integrated. An optical fiber retaining portion is formed on the extension, and the other end of the rod-shaped support is positioned on the fixed portion of the terminal connection device provided on the extension of the axis of the optical cable. There is provided an optical fiber holding device which forms a rod-like support holding portion for supporting after the adjustment.

As described above, according to the present invention, a cylindrical retaining disk and a linear bonding groove are not required. In the conventional apparatus, the lower limit of the retaining disk diameter is determined from the allowable bending radius of the optical fiber core wire, and it is difficult to shorten the length of the linear bonding, and the terminal connection apparatus becomes large. The retaining device of the present invention has an effect that it can be accommodated in the taper pin and the terminal connecting device can be kept small.
In addition, retaining with an adhesive that is dried near room temperature requires a long curing time, and the use of UV curable resin requires special equipment, but hot melt adhesives can be processed in a short time without the need for special equipment. This has the effect of reducing work time.

  Furthermore, since it can be adjusted by the joining process of the caulking sleeve and the support body in the final process, there is no problem even if the position accuracy in the longitudinal direction of the initial retaining part formation is somewhat low, and the high workability also helps to reduce the cost. .

  An optical fiber holding device according to an embodiment of the present invention is shown in FIGS. FIG. 1 is a perspective view showing a retaining portion 30a as a main part of an optical fiber retaining device 30, wherein (a) shows a state before heating and (b) shows a state formed as a retaining portion 30a after heating. . FIG. 2 is a cross-sectional view taken along a plane including the axis of the optical fiber and a plane perpendicular to the axis, wherein (a) and (c) show before heating, and (b) and (d) show after heating.

The retaining portion 30a is inserted into a hollow portion of a heat shrinkable tube 33 having a hollow substantially circular cross section, and a tubular hot melt adhesive 31 having a substantially elliptical cross section and an elongated rod-shaped support body 32 are inserted. Has been.
The heat-shrinkable tube 33 and the hot-melt adhesive 31 have a length that becomes the retaining portion length L shown in FIG.
In the figure, the right direction is the optical cable side, and the left direction is the connection side of the terminal connector.

The support 32 is formed of a metal wire such as a stainless steel wire. In order to increase the restraining force acting in the axial direction of the support body 32 from the hot melt adhesive 31 and the heat shrinkable tube 33 after the heating, as shown in FIG. You may cut and form uneven | corrugated shape. After heating, the support 32 is restrained by the hot-melt adhesive 31 or the like whose thread is filled in the thread groove, and is prevented from moving in the axial direction. As long as the restraining force exerted in the axial direction of the support 32 is increased, the uneven shape may be, for example, a large number of rings, irregular grooves, or the like other than screws.
One end (right side in the figure) of the support 32 substantially coincides with the end of the heat-shrinkable tube 33, and the other end (left side in the figure) is a predetermined for attaching a caulking sleeve 34 that is a support sleeve for holding the support, which will be described later. The length has been extended.

The terminal portions of the plurality of optical fibers 1 a taken out from the optical cable are inserted into the holes of the hot melt adhesive 31. If the optical fiber 1a is, for example, an optical fiber in the loose tube type unit shown in FIGS. 7 and 8, the loose tube 1d is cut and the jelly-like compound 1c is wiped and inserted. When the loose tube shown in FIG. 12 is lacking, it may be pulled out from the pressure-resistant layer or pressure-resistant shell and wiped off the jelly-like compound 1c and inserted.
The tip portion on the connection side of the optical fiber core wire has a length that allows sufficient connection processing.
In addition, as shown in FIG. 4 or FIG. 11 (a) demonstrated in detail later, the insulating layers (sheaths) 5 and 6 which comprise the outer peripheral part of a submarine optical cable are removed, and the structural member of the pressure | voltage resistant layer 2 or the tensile strength layer 3 is removed. Is detained separately.

  In the state before heating shown in FIGS. 1 (a) and 2 (a), as shown in FIG. 2 (c) showing the cross section, a plurality of optical fiber cores 1a are formed in the holes of the hot melt adhesive 31. The hot melt adhesive 31 and the support 32 are inserted through the hole of the heat shrinkable tube 33 without difficulty. At this stage, the constituent members are not coupled to each other and can be moved individually when an external force is applied.

When the heat shrinkable tube 33 is heated using a heater (not shown), the hot melt adhesive 31 is softened and melted and flows into the gap between the optical fiber core wire 1a and the support 32, and the heat shrinkable tube 33 is The length of each part is reduced by heating, and in particular, the diameter of the tube is reduced.
As shown in FIGS. 1, 2 (b) and 2 (d), the hot-melt adhesive 31 in which the periphery of the optical fiber core 1a and the support 32 is filled without any gap is reduced in diameter. 33 holes are filled.
When the heating is stopped and the temperature is lowered, the hot melt adhesive 31 is solidified to bond the optical fiber 1a and the support 32, and is integrated with the heat shrinkable tube 33 to form the retaining portion 30a.

  Since the volume change due to the temperature of the hot melt adhesive 31 can be ignored, if the inner volume of the hole of the heat shrinkable tube 33 after shrinkage and the volume of the hot melt adhesive 31 are adjusted in advance, A sufficient adhesive force can be obtained without causing any abnormality in the transmission characteristics of the optical fiber core wire due to the ambient pressure.

As described above, the primary and secondary resin coatings are formed on the vitreous surfaces constituting the core and the clad of the optical fiber 1a mainly for the purpose of increasing the protection from external force and the mechanical strength.
The primary coating is made of thermosetting silicone resin, ultraviolet (UV) curable acrylic or epoxy resin, and the secondary coating is made of UV curable resin, nylon or the like. UV) curable resins tend to be used frequently.

As the hot melt adhesive 31, a thermoplastic resin is used as a base material, and EVA (ethylene vinyl acetate copolymer) type and the like are practically used. The hot melt adhesive is melted by heating with a heater. Since the viscosity of the melted resin is reduced to some extent, it is easily filled in the gap between the optical fiber core wire 1a and the support 32 as described above. When the heating by the heater is finished and the temperature is lowered, it is solidified and bonded while being filled.
As described above, the resin used for the hot melt adhesive 31 is made of a thermoplastic resin as a base material, and an ultraviolet (UV) curable resin of a series of thermosetting resins used as an optical fiber coating, etc. Is completely different.

As the material of the heat shrinkable tube 33, heat shrinkable silicone rubber or the like is prominent.
Silicone rubber has the highest heat resistance and cold resistance, and can be used in a wide range of −70 to 200 ° C. without significant deterioration in properties. As a special silicon rubber, a self-bonding or heat-shrinkable silicone rubber is used as a heat-resistant insulating tape, a heat-shrinkable tube or the like.
The heat-shrinkable tube is also used for bundling electric wire bundles for inter-board wiring of electronic equipment, and is used by contracting it with hot air from outside using a heater or the like. It is also used for coating optical fiber connections.

The heat-shrinkable tube 33 is contracted by heating, and the optical fiber 1a and the support 32 are bonded by melting the hot-melt adhesive 31, and these are integrated to form the retaining portion 30a.
Normally, as shown at the left end of FIG. 2 (b), a caulking sleeve 34 (indicated by a one-dot chain line) is fixed near the tip of the support body 32, and the support body 32 is connected to the terminal connector via the caulking sleeve 34. It is convenient to keep it in a pressure-resistant cylinder or an equivalent member.
The details of the retaining method using the caulking sleeve 34 will be described later.

The retaining portion 30a before heating has little coupling force between the constituent members, and there is a concern that the members may be misaligned during the heating operation. FIG. 3 mainly improves the workability by changing the cross-sectional shape of the hot-melt adhesive 31.
3 (a1), (b1), and (c1) are before heating, and FIGS. 3 (a2), (b2), and (c2) are optical fiber cores 1a of the retaining portion 30a formed integrally after heating. It is sectional drawing orthogonal to an axis.
FIGS. 3A2, 3B2 and 3C2 show the same state as that shown in FIG.

  FIG. 3A1 shows a hot melt adhesive 31a inserted into a heat shrinkable tube 33 before heating and lightly bonded. The hot melt adhesive 31a and the heat shrinkable tube 33 are integrated. The optical fiber core wire 1a and the support 32 are inserted into the holes of the hot melt adhesive 31a. When the hot-melt adhesive 31a is solidified after heating and melting, it fills the space between the optical fiber core wire 1a and the support 32 and becomes FIG. 3 (a2).

  In FIG. 3 (b1), the surface of the support 32 is previously covered with a hot-melt adhesive 31b in order to surely avoid direct contact between the uneven shape formed on the surface of the support 32 and the optical fiber core wire 1a. . The sum of the cross-sectional areas of the hot-melt adhesive 31a having a cylindrical cross section and the hot-melt adhesive 31b on the support surface is a predetermined amount of the hot-melt adhesive. The hot-melt adhesive 31a is inserted into the heat-shrinkable tube 33 before heating and is lightly bonded as in FIG. 3 (a1).

FIG. 3 (c1) is an embodiment having the best workability. The support 32 is embedded in the solid part of the hot melt adhesive 31d in advance and fixed, and the hot melt adhesive 31d is heated before being heated. It is inserted into 33 and lightly adhered.
In this case, if the optical fiber core wire 1a is inserted into the hole of the hot melt adhesive 31d and positioned, the positional relationship with other members can be automatically determined.

Next, details of the terminal connection device used for connecting the submarine optical cable will be described with reference to FIG. There are various types of terminal connection devices such as JB, CPL, and EB, all of which connect cables mechanically, electrically, and optically. That is, the optical fiber and the power supply path are connected, the tension members are retained, and the tension between the cables is transmitted. Here, a joint box (JB) for connecting two submarine optical cables will be described.
FIG. 4A is a projection view showing the outer shape of the JB, and the submarine optical cables 50a and 50b inserted from the left and right are guided through the central hole of the boot 25 to the central JB body 20a.

The submarine optical cables 50a and 50b are mechanically, electrically and optically connected by the JB main body 20a inside the cylindrical cover 21 at the center. The internal structure of the JB main body 20a may be considered to be substantially bilaterally symmetric, and FIG. 4B shows a cross-sectional view of the inside of the circle A corresponding to the right half taken along a plane including the axis of the optical cable.
Since the submarine optical cables 50a and 50b are connected in substantially the same manner and in the holding method, and the structure is substantially similar, only the holding device portion corresponding to the cable 50b is shown. It can be considered that the structure with respect to the cable 50a is substantially the mirror image relationship of FIG.

The submarine optical cables 50a and 50b are described as cables having the loose tube type unit shown in FIG. 7 as an example. However, the submarine optical cables 50a and 50b are also applicable to cables having the loose tube function shown in FIG.
A boot 25 made of rubber or the like and an internal boot insert 26 protect the optical cables 50a and 50b from external force, and can be wound on a reel simultaneously with the connected optical cable.
In FIG. 4B, the cable 50b is inserted through the hole in the center of the mold 23 with the insulating layers 5 and 6 removed.

The structure of the JB main body 20a will be described.
The anchor disk 11 is inserted into the hole in the center of the end plate formed at both ends of the cylindrical pressure-resistant cylinder 28 made of metal.
The pressure-resistant cylinder 28 protects the connecting portion of the optical fiber core housed therein from external forces such as water pressure and bending, and transmits the tension between the optical cables 50a and 50b to be connected and the electrical connection of the feeding path. Is going. For this reason, the pressure-resistant cylinder 28 is formed of a high-strength metal, and its periphery is covered with the insulator 22 and the mold 23 to insulate it from seawater.
Further, it is covered with a cylindrical cover 21 made of metal, and boot inserts 26 are coupled to both ends of the cover 21 by screwing or the like.

  The connection portion of the optical fibers 1a of the two optical cables 50a and 50b is accommodated in the pressure-resistant cylinder 28. However, a considerable margin length, that is, an extra length is required for connection work and the like. In order to accommodate the optical fiber so as not to deteriorate the transmission characteristics or the like, an extra-length accommodating body 24 for accommodating the connected optical fiber core wire 1a is provided on the inner peripheral surface of the pressure-resistant cylinder 28.

The divided pieces 2a and the steel wires (tensile wires) 3a, 3b, etc. are placed on the tapered inner peripheral surface of the anchor disk 11 so as not to overlap, and the outer peripheral surface of the taper pin 13 having a taper of substantially the same angle. It is pinched and retained.
The taper pin 13 is pushed in from the left through the flange 14, and firmly holds the divided pieces 2a and the steel wires (tensile wires) 3a and 3b. Furthermore, the clamp nut 15 is fixed so that the position does not move. The clamp nut 15 is fixed by, for example, a means of screwing a male screw cut on the outer peripheral surface of the clamp nut 15 with a female screw formed on the left end portion of the anchor disk 14.
The loose tube 1d is held by the adhesive force of the compound 7 between the divided pieces 2a, but is connected to the loose tube 1d and a pressure-resistant cylinder 28 such as an anchor disk 11 with respect to the terminal. It is more preferable to take a retaining method such as adhering to the other member.

The optical fiber 1a has already been fixed together with the support body 32 by a hot melt adhesive 31 and a heat shrinkable tube 33 to form a retaining portion 30a.
The retaining portion 30 a is inserted through holes 13 a, 14 a, 15 a provided at the centers of the taper pin 13, the flange 14, and the clamp nut 15. The distal end portion of the support 32 reaches the inside of the pressure-resistant cylinder 28.

The optical fiber core wire 1 a is retained by supporting the retaining portion 30 a formed on the optical fiber 1 a by the anchor disk 11. Needless to say, even if the anchor disk 11 is not directly supported, the anchor disk 11 may be supported by a structure that is recognized as being integral with the anchor disk 11.
As an example, the caulking sleeve 34 can be fixed to the left end portion of the support body 32 to hold the optical fiber core wire 1a.

The caulking sleeve 34 can be secured to the support 32 by, for example, caulking. However, if the caulking process is performed after the divided pieces 2a and the steel wires (strength wires) 3a and 3b are retained, the light The fiber core can be held with an optimum tension. That is, the caulking sleeve 34 may be fixed in a state where the support 32 is pulled to the left in the drawing and an appropriate tension is applied to the optical fiber.
The caulking sleeve 34 is a substantially cylindrical member, and has a structure in which a support is passed through a central hole. For example, the caulking sleeve 34 is deformed by applying a force from the outside and is fixed to the support 32 by pressing.

The caulking sleeve 34 can be used in various holding methods (support methods). As an example, in FIG. 4B, the metal plate support bracket 17 shown in FIG. 4C is fixed to the anchor disk 11 with screws 17b. The support body 32 is inserted into the groove 17a at the tip, and the right end of the caulking sleeve 34 is supported by the support fitting 17 and retained.
As an actual work procedure, the support body 32 is inserted into the groove 17a of the support fitting 17 fixed to the anchor disk 11, and the tip of the support body 32 is pulled to be suitable for the optical fiber core wire 1a via the retaining portion 30a. The crimping sleeve 34 is crimped and fixed to the support body 32 at a position where the caulking sleeve 34 contacts the support fitting 17 while applying a sufficient tension. Thereafter, the caulking sleeve 34 is supported by the support fitting 17 and keeps the optical fiber core wire 1a.

Depending on the structure of the terminal connector, without using the caulking sleeve 34, as shown on the right side of FIG. It can also be supported.
In this case, the support body 32 may not be provided mechanically. However, it is preferable to insert the support body 32 having the same length as the length L of the retaining portion 30a in order to ensure the rigidity of the retaining portion 30a.

Next, the retaining performance of the retaining device of the present invention will be described with reference to the graph of FIG. FIG. 5 shows the retaining force when the length L of the retaining portion 30a is changed in FIG. The holding force is converted with the tension for extending the optical fiber by 1% as 100%.
If the length of the retaining portion 30a is approximately 30 mm, 130% can be secured, and if it exceeds 60 mm, 300% can be secured. In general, the optical fiber used for the submarine cable requires a screening test with a tension equivalent to 2.2% elongation in the deep sea of 1% and 5000m even in the shallow water. Even if the length of the retaining portion 30a is 30mm, it is for shallow water. If it is 60 mm, it has sufficient strength for deep sea use.
In order to ensure the reliability of the optical fiber, a screening test is performed in which a load corresponding to a predetermined elongation is applied to the total number (total length) of the optical fibers, and only the passed optical fibers are used for the cable.

It has also been confirmed that there is no change in the transmission characteristics of the optical fiber when a load of 1% elongation (100%) is applied to the retaining portion 30a of the present invention.
Originally, the hot-melt adhesive and heat-shrinkable tube used in the present invention have already been used for a long time as a protective sleeve for fiber connection for connecting an optical fiber core wire halfway. Normally, the optical fiber core wire is peeled off to the primary coating of the fiber strand at the connection part, the core position between the fibers is confirmed and welded with the core wire connector, and the periphery of the joint part is joined with hot melt adhesive and heat. A method of covering and heating with a shrink tube to protect the periphery of the joint is used. At this time, the steel wire may be laid along the joint to cope with the bending external force.
It has also been confirmed that there is no change in transmission characteristics due to the retaining portion applying a lateral pressure to the optical fiber.
Therefore, it can be considered that the durability of the hot-melt adhesive and the heat shrinkable tube is also guaranteed from the durability of the optical fiber connection portion laid on the seabed and collected after being left for a long time.
As described above, the initial performance and long-term stability are guaranteed from the experimental results and the use results of the fiber connection protective sleeve used for the submarine cable, and the optical fiber core wire retaining device according to the present invention is employed with peace of mind. be able to.

  As described above, the example in which the optical fiber core retaining device of the present invention is applied to the submarine optical cable has been described. However, the optical fiber core retaining device of the present invention is not limited to the submarine cable but also to the optical cable used on land. Is also widely applicable.

It is the perspective view which showed the example of embodiment of the optical fiber drawing apparatus of this invention before and the form after a heating. It is the projection which showed embodiment of this invention shown in the perspective view of FIG. 1 as sectional drawing. It is sectional drawing orthogonal to the axis line of an optical fiber core wire of the optical fiber drawing apparatus which is another embodiment of this invention. It is sectional drawing which shows an example of the terminal connection apparatus (JB) carrying the optical fiber drawing apparatus of this invention, and the retention method of a support body. It is a graph which shows the retention capability of the optical fiber retention device of this invention. It is a schematic diagram explaining the format of the optical fiber unit built in the center part of a submarine optical cable. It is a perspective view which shows the internal structure of a submarine optical cable. It is sectional drawing orthogonal to the longitudinal direction of the submarine optical cable shown in FIG. It is a perspective view which shows the internal structure of the submarine optical cable of a structure different from FIG. FIG. 10 is a cross-sectional view perpendicular to the longitudinal direction of the submarine optical cable shown in FIG. 9. It is a conventional example of a method for retaining an optical cable in a loose tube. It is a perspective view of two types of submarine optical cables which also have the function of a loose tube with a pressure-resistant shell without having a loose tube.

Explanation of symbols

1 loose tube type unit, 1a optical fiber (core wire), 1c jelly-like filler, 1d loose tube,
2 pressure-resistant layer, 2a divided piece, 3 tensile layer, 3a, 3b steel wire (tensile wire), 4 metal tube layer, 5, 6 insulating layer (sheath),
7, compound (adhesive or adhesive), 8 compound (intermittent filling),
50, 50a, 50b Submarine optical cable, 20 terminal connecting device, 20a JB main body, 24 extra length storage body, 25 boot, 27 insulator, 28 pressure cylinder,
30 optical fiber retaining device, 30a retaining portion, 31 hot melt adhesive, 32 support (steel wire), 32a screw portion (uneven shape), 33 heat shrinkable tube, 34 caulking sleeve

Claims (1)

Installed inside a terminal connection device for connecting an optical cable having a loose tube type unit in which a single core or a plurality of optical fibers are inserted into a cylindrical tube made of metal or resin together with a jelly-like filler, and inserted into the optical cable An optical fiber holding device for holding one or more optical fibers,
A tubular hot-melt adhesive having a hollow portion;
A tubular heat-shrinkable tube having a hollow portion;
A rod-shaped support,
The hot melt adhesive is inserted into the hollow portion of the heat shrinkable tube, and one end of the rod-shaped support is disposed in the hollow portion, the solid portion, or the outer peripheral portion of the hot melt adhesive. The at least one optical fiber is inserted into the hollow portion of the hot melt adhesive and heated to melt the hot melt adhesive and contract the heat shrinkable tube to form the rod An optical fiber retaining portion is formed on the extension of the axis of the optical cable as an integral structure with one end of the support of the optical fiber and the optical fiber, and the other end of the rod-like support is extended on the extension of the axis of the optical cable. A rod-like support retaining portion for supporting the rod-like support after adjusting the position of the rod-like support is formed in a fixed portion of the terminal connection device provided in the light. Fiber retention device.

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