JP2012155230A - Optical fiber cable, and branching method for optical fiber cable - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical fiber cable etc., which has its coating easily removed and is superior in branching operability.SOLUTION: A plurality of coated fibers 7 are arranged at a substantially center position in a section of an optical fiber cable 1. A buffer layer 8 is provided to the outer peripheral of the coated fibers 7 when necessary. A coating part 3 is provided to the outer periphery of the buffer layer 8. Tension members 9 and tearing cords 11 are provided in the coating part 3. A plurality of notches 5 are provided in the outer peripheral surface of the coating part 3. At least a pair of notches 5 are formed. The pair of notches 5 are V-shaped notch parts, and formed in mutually opposite directions. Namely, the notches 5 are formed not facing the center of the optical fiber cable 1. A line connecting tips of the pair of notches 5 is a cutting line 13. The cutting line 13 is a part to be cut with a cutting tool when the coating part 3 is removed. The tearing cords 11 are provided on the cutting lines 13.

Description

  The present invention relates to an optical fiber cable excellent in branching workability and a method for branching an optical fiber cable.

  Conventionally, an optical fiber cable in which an optical fiber core wire is covered with a jacket is used. In use, such an optical fiber cable is branched and wired to a plurality of houses.

  As such an optical fiber cable, for example, there is a longitudinally continuous notch that bites into the sheath on the inner surface of the cable sheath, and the root portion is located on the outer surface of the cable sheath across both sides of the notch in parallel with the notch. There is an optical fiber cable having a protrusion (Patent Document 1).

  The cable sheath has at least two external notches continuous in the longitudinal direction that bite into the sheath toward the center, and a straight line connecting between the tips of the two external notches exists in the sheath. There is an optical fiber cable in which sheath tearing means is formed so as to be positioned between two external notches in parallel with the external notch (Patent Document 2).

JP 2008-158177 A JP 2008-158368 A

  However, when the protrusion is formed as in Patent Document 1, the winding property is poor when the fiber cable is wound around the drum, and such a small protrusion may be easily worn and damaged when laid. . Further, in both optical fiber cables of Patent Documents 1 and 2, a cutting tool is used when the internal optical fiber core is branched, but the operation is dangerous and the cutting tool may slip.

  On the other hand, a blade such as a general cutter may be used for removing the coating of the optical fiber cable, instead of a dedicated cutting tool. In this case, it is necessary to remove the covering portion little by little from the outer periphery with respect to the opening starting point portion provided inside.

  However, in such a method, it takes time to expose the opening starting point of the inside, and there is a risk of damaging the internal optical fiber.

  The present invention has been made in view of such problems, and an object of the present invention is to provide an optical fiber cable or the like that can be easily removed and has excellent branching workability.

  In order to achieve the above-described object, the first invention is an optical fiber cable having at least a fiber core wire and a covering portion that covers the fiber core wire, and the cable portion has a substantially circular cross-sectional shape, In the cross section of the covering portion, a plurality of notches are formed from the outer periphery of the covering portion, and at least a pair of the notches are provided at positions facing each other on the covering portion, and are on a cutting line connecting the ends of the pair of notches The optical fiber cable is characterized in that an opening starting point portion is disposed in the upper end surface and an extension line of the cutting line divides an upper end surface and a lower end surface of the notch portion.

  An upper end surface or a lower end surface of the notch portion may be substantially parallel to the cutting line.

  The opening start point may be a tear string. In this case, it is desirable that the notch is provided so that the cutting line is located between the center of the tear string and the outer end of the tear string.

  The opening start point may be a recess that communicates with a buffer layer that holds the optical fiber core wire. In this case, the concave portion may be filled with a filler.

  The notch portion may be filled with a filler.

  According to the first invention, at least a pair of notches are provided on the outer periphery of the covering portion, and the opening start point portion is provided on the cutting line connecting the tips of the notches. Accordingly, the opening start point can be reliably exposed by cutting with the blade so as to connect the tips of the notches. At this time, since the upper end surface or the lower end surface of the notch does not overlap with the cutting line, the cutting line connecting the notch tips can be surely cut with the blade.

  In addition, when either the upper end surface or the lower end surface of the notch portion is provided substantially parallel to the cutting line, when the fiber coating portion is cut along the axial direction with the cutter, the cutter is cut into the upper end surface or the lower end surface. Can be moved along. For this reason, a cutter can be moved straight at the time of coating removal. Therefore, the internal optical fiber core wire is not damaged, and the opening start point is not excessively cut. Moreover, the opening start point can be surely exposed by one-time cutting.

  A tear string can be used as the opening start portion. In this case, the position of the cutting line is from the center of the tear string to the outer end (the portion that is the outermost periphery in the radial direction when viewed from the center of the optical fiber cable, and the circumscribed circle of the tear string with respect to the center. The notch is provided so as to be positioned between the contact points), and when the covering portion is removed with the blade along the cutting line, the tear string is cut or the internal optical fiber core wire is damaged. There is nothing.

  Moreover, it can also be set as the recessed part connected to a buffer layer as a mouth opening starting part. In this case, filling the concave portion with the filler can prevent the optical fiber core wire from entering the concave portion. For this reason, when removing a coating | coated part, an internal optical fiber core wire is not damaged.

  Further, by providing a filler in the notch portion on the outer periphery, the outer shape becomes a substantially circular cross-section, and for example, even when placed in a closure or the like, it is easy to stop water on the outer periphery of the optical fiber cable.

  2nd invention has a fiber core wire and the coating | coated part which coat | covers the said fiber core wire at least, A cable part is a substantially circular cross-sectional shape, From the outer periphery of the said coating | coated part in the cross section of the said coating | coated part. A plurality of notches are formed, and at least the pair of notches are provided at positions facing each other of the covering portion, and both the upper end surface and the lower end surface of the notch portion cut the ends of the pair of notches. A method of branching an optical fiber cable that does not overlap an extended line of a wire, wherein a tear string is disposed on the cutting line, the cutting line is cut with a blade along the notch to expose the tear string, and the tear An optical fiber cable branching method characterized in that an inner fiber core wire is exposed by pulling off a string, and the fiber core wire is taken out.

  According to the second invention, the inner optical fiber core wire is not damaged by the blade and can be easily branched.

  According to the present invention, it is possible to provide an optical fiber cable or the like that can be easily removed and has excellent branching workability.

It is sectional drawing of the optical fiber cable 1, (a) is a general view, (b) is the A section enlarged view of (a). The figure which shows the positional relationship of the cutting line 13 and the tear string 11. FIG. It is a figure which shows the process of excising a part of coating | cover part and providing the cutting part 18, (a) is a front view, (b) is sectional drawing. It is a figure which shows the process of removing a coating | coated part with the blade 19, (a) is a front view, (b) is sectional drawing. It is a figure which shows the shape of the notch 5, (a) is a figure which shows the state where the upper end surface and lower end surface of a notch do not overlap with a cutting line, (b) is a figure which shows the state where a cutting line and a lower end surface overlap as a comparative example (C) is a figure which shows the state which a cutting line and an upper end surface overlap as a comparative example. The figure which shows the preferable cutting line and the shape of a notch. (A) is sectional drawing which shows the optical fiber cable 30, (b) is sectional drawing which shows the optical fiber cable 30a. (A) is sectional drawing which shows the optical fiber cable 40, (b) is sectional drawing which shows the optical fiber cable 40a. (A) is sectional drawing which shows the optical fiber cable 1a, (b) is sectional drawing which shows the optical fiber cable 30b. Sectional drawing which shows the optical fiber cable 50. FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view of the optical fiber 1, FIG. 1 (a) is an overall view, and FIG. 1 (b) is an enlarged view of part A of FIG. 1 (a). The optical fiber cable 1 includes a covering portion 3, a fiber core wire 7, a tension member 9, a tear string 11, and the like.

  A plurality of fiber core wires 7 are arranged at a substantially center position of the cross section of the optical fiber cable 1. The fiber core wire 7 may be a single fiber, a unit bundled with single fiber, or a tape core. Moreover, when putting in the inside of the protective layer mentioned later, you may wind up the whole optical fiber core wire with a film or a tape, and may integrate. For example, a 0.25 mmΦ core can be used as the fiber core.

  A buffer layer 8 is provided on the outer periphery of the fiber core wire 7 as necessary. The buffer layer 8 is, for example, a fiber such as polypropylene yarn, and is a portion that holds the fiber core wire 7. The buffer layer 8 is merely disposed on the outer periphery of the optical fiber core wire 3 and can be easily removed. As the buffer layer 8, for example, a polypropylene yarn having a thickness of about 1 mm can be used.

  A covering portion 3 is provided on the outer periphery of the buffer layer 8. As the coating | coated part 3, resin, such as a flame-retardant polyethylene, can be used, for example. A tension member 9 is embedded in the covering portion 3. The tension member 9 is a part responsible for the tension of the optical fiber cable 1. As the tension member 9, for example, a fiber reinforced plastic made of steel wire, monofilament, aramid fiber or the like can be used. The outer diameter of the covering portion 3 is, for example, about 8 mm, and the tension member 9 may be about 1 mmΦ.

  A tear string 11 that is a starting point for opening a mouth is provided outside the buffer layer 8 and at a position different from the tension member 9. As the tear string 11, for example, a polyester twisted yarn can be used.

  Plural (preferably two or more pairs, two examples are shown in the figure) are provided on the outer peripheral surface of the covering portion 3. At least a pair of notches 5 are formed. The pair of notches 5 are V-shaped notch portions and are formed in directions facing each other. That is, the notch 5 is not formed toward the center direction of the optical fiber cable 1.

  As shown in FIG. 1B, a line connecting the tips of the pair of notches 5 is a cutting line 13. The cutting line 13 becomes a part to be cut with a blade when the covering portion 3 described later is removed. The tear string 11 is provided on the cutting line 13. The depth of the notch 5 (the length from the intersection of the extension line of the cutting line 13 and the outer circumference of the optical fiber cable 1 to the tip of the notch 5) may be about 1.2 mm. Details of the shape of the notch 5 will be described later.

  FIG. 2 is an enlarged view of a portion B in FIG. As shown in FIG. 2, the cutting line 13 is a position (C in the drawing) in the range from the center 15 of the tear string 11 to the outer end 17 (the end portion that is the outermost peripheral position with respect to the optical fiber cable of the tear string 11). It is desirable that By doing in this way, it can prevent that the tearing cord 11 and an internal fiber core wire are damaged accidentally at the time of the coating | coated part removal operation mentioned later.

  Next, a branching method using the optical fiber cable 1 according to the present invention will be described. FIGS. 3A and 3B are diagrams showing a process of removing a part of the covering portion 3 to provide a cut portion 18, in which FIG. 3A is a front view and FIG. 3B is a cross-sectional view. First, as shown in FIG. 3, the cut portion 18 is formed by scraping off a part of the covering portion 3 with a blade to the branch target portion of the optical fiber cable 1. The cut portion 18 may be formed in a range longer than the width of the blade used.

  When the cut portion 18 is formed, the notch 5 serves as a standard for the range in which the covering portion 3 is removed. That is, as shown in FIG. 3B, by inserting the blades to the depths of the respective tips of the pair of notches 5 facing each other, the blades enter below the cutting line 13 (center direction of the optical fiber cable). There is no. Therefore, it is possible to prevent the inner fiber core wire from being damaged by the blade (cut portion 18) entering the buffer layer 8 or the like.

  Next, as shown in FIG. 4, the covering portion 3 is removed by the blade 19 starting from the cut portion 18. As shown in FIG. 4B, when the blade 19 is disposed at a substantially central portion of the cut portion 18 (the straight portion of the cut portion 18 in FIG. 3A), the blade 19 is disposed on the cutting line 13. Therefore, by moving the blade 19 along the notch 5 in the axial direction of the optical fiber cable 1 (in the direction of arrow D in the figure), the blade 19 covers the upper side of the notch 5 (in the radial outer peripheral side of the optical fiber cable 1). Part 3 can be removed.

  At this time, since the blade 19 can be moved along the pair of notches 5, it can be moved straight in the axial direction of the optical fiber cable 1. That is, the covering portion 3 in a predetermined range can be reliably removed at the same depth by a single cutting (movement of the blade 19). At this time, since the cutting depth is constant, the inner fiber core wire 7 is not damaged.

  When the covering portion 3 in a predetermined range is removed, the internal tear string 11 is exposed in the range. For this reason, when the tear string 11 is taken out and pulled, the covering portion 3 is torn and a mouth opening portion is formed. Therefore, the inner fiber core wire 7 can be taken out from the opening portion. The branching operation is performed as described above.

  Next, the shape of the notch 5 will be described. FIG. 5 is a partially enlarged view of the optical fiber cable 1 in which the shape of the notch 5 is changed. One end surface (inner surface) of the notch 5 in the cross section is defined as an upper end surface 5a, and the other end surface (inner surface) is defined as a lower end surface 5b. That is, the notch 5 is composed of an upper end surface 5a and a lower end surface 5b. The angle of the notch 5 (the angle between the upper end surface 5a and the lower end surface 5b) may be about 25 °, for example.

  As shown in FIG. 5A, in the present invention, when an extension line of the cutting line 13 is assumed, the straight line does not overlap the upper end surface 5a and the lower end surface 5b of the notch 5. That is, the upper end surface 5a and the lower end surface 5b of the notch 5 are separated by an extension line of the cutting line 13 passing through the tip of the notch 5. By doing in this way, when cut | disconnecting the cut surface 13, a cutting range becomes only between the front-end | tips of a pair of notches 5. FIG.

  On the other hand, as shown in FIG. 5B, when the notches 5 are arranged so as to face the center direction of the optical fiber cable 1 from the opposing directions, the extension line of the cutting line 13 passing through the tip of the notch 5 Both the upper end surface 5a and the lower end surface 5b of the notch 5 are located on the upper side (the outer peripheral direction of the optical fiber cable 1). That is, an overlapping portion 21 between the cutting line 13 and the lower end surface 5b is formed. For this reason, when the cut surface 13 is cut, the overlapping portion 21 is cut by the blade. Accordingly, the cutting resistance is large, and the cutting waste at the part is generated.

  Similarly, as illustrated in FIG. 5C, when the notches 5 are arranged so as to face the outer peripheral direction of the optical fiber cable 1 from the opposing directions, an extension line of the cutting line 13 passing through the tip of the notch 5. Both the upper end surface 5a and the lower end surface 5b of the notch 5 are located on the lower side (in the central direction of the optical fiber cable 1). That is, an overlapping portion 21 between the cutting line 13 and the upper end surface 5a is formed. For this reason, when the cut surface 13 is cut, the overlapping portion 21 is cut by the blade. Accordingly, the cutting resistance is large, and the cutting waste at the part is generated. Accordingly, the cutting resistance is large, and the cutting waste at the part is generated.

  As described above, in the present invention, as shown in FIG. 5A, the cutting line 13 (extension line thereof) does not overlap the covering portion 3 at the notch 5 and opens in the extending circle direction of the cutting line 13. Is desirable.

  More preferably, as shown in FIG. 6, the cutting line 13 (extension line thereof) is preferably parallel to the upper end surface 5a or the lower end surface 5b of the notch 5 (FIG. 6 shows the lower end surface 5b and the cutting line). 13 is parallel). That is, it is desirable that the upper end surface 5a or the lower end surface 5b of the notch 5 and the extension line of the cutting line 13 substantially coincide.

  In this way, as shown in FIG. 4, when the blade 19 is moved along the notch 5, for example, the lower surface of the blade 19 and the lower end surface 5 b of the notch 5 are in surface contact, and the vertical direction of the blade 19 is increased. The direction can be made more certain. Therefore, when the covering part 3 is cut with the blade 19, the tear string 11, the fiber core wire 7 and the like are not cut by mistake.

  As described above, according to the present embodiment, the optical fiber cable 1 can be easily branched without damaging the internal optical fiber core wire. Further, since the notch 5 is provided when the covering portion 3 is cut off with the blade 19, the blade 19 is not accidentally inserted too deeply, and is covered with the blade little by little until the tear string 11 is exposed. There is no need to scrape off parts. For this reason, it is excellent in branch workability.

  Further, the upper end surface 5 a and the lower end surface 5 b of the notch 5 are separated by an extension line of the cutting line 13 passing through the tip of the notch 5. For this reason, when cutting the coating | coated part 3 with the cutter 19, the upper end surface 5a or the lower end surface 5b of the notch 5 is not scraped off. Further, the vertical direction of the blade 19 can be stabilized.

  Further, since the cutting line 13 is positioned between the center 15 and the outer end 17 of the tear string 11, the fiber core wire 7 is not cut into the tear string 11 or the inside when the cutting tool 19 cuts.

  Next, another embodiment will be described. In the following embodiment, the same reference numerals as those in FIG. 1 are used for the same functions as those of the optical fiber cable 1 shown in FIG.

  FIG. 7A is a cross-sectional view showing the optical fiber cable 30. The optical fiber cable 30 differs from the optical fiber cable 1 in that a recess 31 is formed instead of the tear string 11. The recess 31 that is the opening start portion is a portion that communicates with the buffer layer 8, and is a recess formed on the inner peripheral surface side of the covering portion 3.

  The recess 31 is formed on a line (cut line 13 in FIG. 1B) connecting the tips of the pair of notches 5 facing each other. Therefore, as shown in FIGS. 3 and 4, when the cutting line is cut with a blade, the recess 31 can be exposed on the cut surface. Therefore, the opening portion can be formed in the covering portion 3 by the concave portion 31, and the internal fiber core wire 7 can be taken out.

  Moreover, it is good also as an optical fiber cable 30a as shown in FIG.7 (b). In the optical fiber cable 30a, the above-described recess 31 is filled with the filler 33. The filler 33 is a low-strength fracture material such as elastomer (rubber). For example, EEA resin (ethylene / ethyl acrylate copolymer resin), EVA resin (ethylene / vinyl acetate copolymer resin), thermoplastic elastomer, polyurethane Silicon, low density polyethylene, linear low density polyethylene, medium density polyolefin, and the like can be used.

  By filling the concave portion 31 with the filler 33, the inner fiber core wire 7 does not fit into the concave portion 31. For this reason, when part of the recessed part 31 is excised with a cutter, the optical fiber core wire fitted in the recessed part 31 is not cut.

  Moreover, it is good also as an optical fiber cable 40 as shown to Fig.8 (a). The optical fiber cable 40 is one in which the tear string 11 is further provided in the recess 31. That is, the tear string 11 of the optical fiber cable 1 is provided inside the recess 31. By doing in this way, the effect of both the tear string 11 and the recessed part 31 can be acquired.

  Moreover, it is good also as an optical fiber cable 40a as shown in FIG.8 (b). In the optical fiber cable 40a, the concave portion 31 in which the tear string 11 is provided is further filled with a filler 33. By doing in this way, the effect of the filler 33 can be acquired further.

  Further, as shown in FIGS. 9A and 9B, optical fiber cables 1a and 30b in which the notch 5 is filled with a filler 33 can also be used. By filling the notch 5 with the filler 33, the outer peripheral surface of the optical fiber cable can be formed into a circular cross-sectional shape. For this reason, for example, even if a seal is provided on the outer peripheral surface of the optical fiber cable and the optical fiber cable is used in a portion where water stop is required, water or the like does not enter through the notch 5.

  The present invention is also applicable to a self-supporting optical fiber cable 50 as shown in FIG. The optical fiber cable 50 is formed by connecting a support line 51 to a cable portion 53 similar to that of the optical fiber cable 1, for example. For the self-supporting optical fiber cable, the portion excluding the portion of the support wire 51 is the cable portion 53, and the cable portion 53 is included in the present invention as long as the cable portion 53 has a substantially circular cross-sectional shape.

  As mentioned above, although embodiment of this invention was described referring an accompanying drawing, the technical scope of this invention is not influenced by embodiment mentioned above. It is obvious for those skilled in the art that various modifications or modifications can be conceived within the scope of the technical idea described in the claims, and these are naturally within the technical scope of the present invention. It is understood that it belongs.

  For example, the configurations described in the above embodiments can be naturally combined.

1, 1a, 30, 30a, 30b, 40, 40a, 50... Optical fiber cable 3... Covered portion 5... Notch 5 a. Line 8 ......... Buffer layer 9 ... ... Tension member 11 ... ... Ripped string 13 ... ... Cutting line 15 ... ... Center 17 ... ... Outer end 18 ... ... Cut section 19 ... ... Cutlery 21 ... ... Overlapping part 31 ... Recess 33 ... Filler 51 ... Support wire 53 ... Cable part

Claims (8)

An optical fiber cable having at least a fiber core wire and a covering portion covering the fiber core wire, the cable portion having a substantially circular cross-sectional shape,
In the cross section of the covering portion,
A plurality of notches are formed from the outer periphery of the covering portion,
At least a pair of the notches are provided at positions facing each other of the covering portion,
A mouth opening starting point portion is disposed on a cutting line connecting the tips of the pair of notches,
An extension line of the cutting line separates an upper end surface and a lower end surface of the notch portion.   The optical fiber cable according to claim 1, wherein an upper end surface or a lower end surface of the notch portion is substantially parallel to the cutting line.   The optical fiber cable according to claim 1, wherein the opening start portion is a tear string.   4. The optical fiber cable according to claim 3, wherein the notch is provided so that the cutting line is located between a center of the tear string and an outer end of the tear string.   3. The optical fiber cable according to claim 1, wherein the opening start portion is a recess that communicates with a buffer layer that holds the optical fiber core wire. 4.   The optical fiber cable according to claim 5, wherein the concave portion is filled with a filler.   The optical fiber cable according to any one of claims 1 to 6, wherein the notch portion is filled with a filler. At least a fiber core wire and a coating portion covering the fiber core wire, and the cable portion has a substantially circular cross-sectional shape,
In the cross section of the covering portion,
A plurality of notches are formed from the outer periphery of the covering portion,
At least a pair of the notches are provided at positions facing each other of the covering portion,
Both of the upper end surface and the lower end surface of the notch portion is a method of branching an optical fiber cable that does not overlap with an extension of a cutting line that connects the ends of the pair of notches,
A tear string is disposed on the cutting line,
Cutting the cutting line with a blade along the notch to expose the tear string,
A method for branching an optical fiber cable, comprising: tearing off the tear string to expose an inner fiber core and taking out the fiber core.

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