JP2014013338A - Optical fiber cable and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical fiber cable capable of increasing the packaging density of optical fibers mounted in a cable.SOLUTION: In an optical fiber cable 5, a plurality of optical units 3 in which a plurality of optical fibers 1 are covered with a film 2 are housed in a cable made of a cylindrical sheath 4. Each the optical units 3 housed in the cable has the same sectional area and is housed in tight contact with each other without clearance in a space inside the cable. After a cross section shape of the optical units 3 is once made circular, the cross section shape is deformed to a fan shape in aggregating the plurality thereof.

Description

  The present invention relates to an optical fiber cable in which a plurality of optical units obtained by coating a plurality of optical fibers with a film are accommodated in a cable made of a cylindrical sheath, and a method for manufacturing the same.

  For example, Patent Document 1 proposes an optical fiber cable in which a plurality of optical units in which a plurality of optical fibers are covered with a plastic film are accommodated in a cable made of a cylindrical sheath.

JP 2009-237341 A

  However, in the optical fiber cable described in Patent Document 1, there is a gap between the optical units, and there is also a gap between the sheath and the optical unit, so the density of the optical fiber mounted in the cable is not sufficient.

  Then, an object of this invention is to provide the optical fiber cable which can raise the mounting density of the optical fiber mounted in a cable, and its manufacturing method.

  A first invention is an optical fiber cable in which a plurality of optical units covered with a film of a plurality of optical fibers are accommodated in a cable made of a cylindrical sheath, and each optical unit accommodated in the cable is The cross-sectional area is the same and is stored in close contact with the space inside the cable without any gap.

  The second invention is characterized in that, in the first invention, the optical units in the cable are arranged in the cable circumferential direction with the cable center as an axis in a cross section orthogonal to the cable longitudinal direction.

  3rd invention is 2nd invention, Comprising: Each said optical unit made the cross-sectional shape fan shape, It is characterized by the above-mentioned.

  4th invention is 1st invention, Comprising: The optical unit in the said cable is arranged in multiple numbers by the circumference direction centering on a cable center in the cross section orthogonal to a cable longitudinal direction, and those circles are carried out to a cable radial direction. A plurality of optical units arranged in the circumferential direction are stacked.

  5th invention is 4th invention, Comprising: The optical unit arrange | positioned at the said cable center makes circular cross-sectional shape, and the optical unit laminated | stacked and arrange | positioned on the outer side has cross-sectional shape said circular optical unit It is characterized in that it has a fan shape with an arc length that equally divides the outer peripheral length.

  A sixth invention is any one of the first to fifth inventions, characterized in that each of the optical units is twisted in the right and left in the circumferential direction in the cable longitudinal direction.

  According to a seventh aspect of the present invention, there is provided a method of manufacturing an optical fiber cable in which a plurality of optical units each having a plurality of optical fibers covered with a film are accommodated in a cable made of a cylindrical sheath. Cover to form a plurality of circular optical units, heat the multiple optical units during assembly, deform the cross-sectional shape of the optical units to make the cross-sectional area of each optical unit the same, and then connect the optical units to the cable It is characterized by being in close contact with the inner space and covered with a sheath.

  According to the present invention, the optical units stored in the cable are stored in close contact with each other in the cable space with the same cross-sectional area, so that the optical units and the sheath and the optical unit are in close contact with each other. As a result, the space in the cable is filled without a gap, and the useless space is eliminated, so that the optical fiber mounting density in the cable can be increased. Moreover, since there is no useless space, waterproof properties can be obtained with a minimum amount of water-stopping material without using an extra water-stopping material, resulting in a reduction in cable costs.

It is a cross-sectional view of the optical fiber cable of this embodiment. The cross-sectional shape of the optical unit which comprises an optical fiber cable is shown, (a) is the circular cross-sectional shape before a deformation | transformation, (b) is the fan shape after a deformation | transformation. It is a cross-sectional view of a conventional optical fiber cable as a comparative example. It is a manufacturing-process figure of the optical fiber cable of this embodiment. It is a cross-sectional view of the optical fiber cable which made the optical unit the laminated structure.

  Hereinafter, specific embodiments to which the present invention is applied will be described in detail with reference to the drawings. As shown in FIGS. 1 and 2, the optical fiber cable of the present embodiment includes a plurality of optical units 3 in which a plurality of optical fibers 1 are covered with a film 2 in a cable 5 including a cylindrical sheath 4. It has a housed structure.

  The optical unit 3 includes an optical fiber 1 and a film 2 that wraps the optical fiber 1 inside. The optical unit 3 has a circular sectional shape as shown in FIG. 2 (a), and is then deformed into a fan shape as shown in FIG. 2 (b) when the optical unit 3 is assembled. ing.

  The optical fiber 1 is composed of a colored optical fiber formed by coating an ultraviolet curable resin and a colored layer around a quartz glass fiber provided at the center. In addition, an optical fiber tape core wire in which a plurality of colored optical fiber strands are arranged and collectively covered with an ultraviolet curable resin, and an optical fiber tape core wire in which colored optical fiber strands adjacent to each other are intermittently fixed are also included in the present invention. It is assumed that the optical fiber 1 is included.

  The film 2 is formed by forming it into a cylindrical shape so that both end edges of the film, which are both ends in the width direction of the belt-shaped plastic film, are formed so as to overlap each other in the circumferential direction. In the film alignment part, the film both ends are merely overlapped without being bonded with an adhesive. If the film alignment part is formed without bonding both ends of the film with an adhesive, it is possible to prevent the optical fiber 1 from jumping out.

  The length in the width direction of the film 2 is desirably longer than the circumferential length of the fan shape × 1.1 when the final fan shape shown in FIG. By doing so, it is possible to secure a stable form of the final shape which is a fan shape, and to prevent the optical fiber from jumping out from the inside.

  Each optical unit 3 has the same cross-sectional shape and is stored in close contact with the space inside the cable without a gap. In this embodiment, the optical units 3 are arranged in the cable circumferential direction with the cable center O as an axis in a cross section orthogonal to the cable longitudinal direction. In FIG. 1, each optical unit 3 is arranged at a position where the internal space of the cable 5 is equally divided into six. Each of these optical units 3 is alternately twisted right and left in the circumferential direction in the longitudinal direction of the cable to form a so-called SZ twist. Of course, it may extend in the longitudinal direction of the cable as it is without SZ twisting, or it may be twisted in one direction (right twist or left twist).

  A water absorbing tape 6 is provided on the inner wall of the sheath 4 so as to wrap the entire optical unit 3. The water absorbing tape 6 not only absorbs moisture in the cable, but also functions as a presser roll that holds the optical units 3 so that they do not fall apart. If the water absorption performance within the cable is not sufficient with the water absorption tape 6 alone, a water absorption yarn may be placed in each optical unit 3 together with the optical fiber 1.

  The sheath 4 is provided with a strength member 7 in the cable longitudinal direction. The strength members 7 are provided at two locations on the same line passing through the center O of the cable 5. Further, the optical fiber cable 1 is provided with a tear string 8 for facilitating the tearing of the sheath 4 at the time of intermediate post branching. The tear string 8 is provided in contact with or near the water-absorbing tape 6 in order to tear the sheath 4 and easily take out the internal optical unit 3.

  According to the optical fiber cable configured as described above, each optical unit 3 housed in the cable 5 is housed in close contact with the inner space of the cable with the same cross-sectional area. Since the space between the sheath 4 and the sheath 4 and the optical unit 3 are in close contact with each other, the space in the cable is completely filled with no gap, and a useless space is eliminated. Therefore, the mounting density of the optical fiber 1 in the cable 5 can be increased. Moreover, since a useless space is eliminated, waterproof properties can be obtained with a minimum water-stopping material (water-absorbing tape 6 or water-absorbing yarn) without using an extra water-stopping material. As a result, the cable cost is reduced.

  Further, according to the optical fiber cable of the present embodiment, the optical unit 3 is arranged in the cable circumferential direction around the center O of the cable 5 in the cross section orthogonal to the cable longitudinal direction. It becomes easier to take out the optical unit 3 than a separately arranged one.

  Moreover, according to the optical fiber cable of this embodiment, since the cross-sectional shape of the optical unit 3 was made into a fan shape, it becomes difficult to make a clearance gap between each optical unit 3, and the optical units 3 mutually adhere.

  Moreover, according to the optical fiber cable of this embodiment, since each optical unit 3 is alternately twisted right and left in the circumferential direction in the cable longitudinal direction, the twist is returned when the sheath 4 is torn at the time of intermediate post branching. It becomes easy to take out the optical unit 3 by loosening.

  The optical fiber cable of this example was manufactured under the following conditions and compared with the optical fiber cable of the comparative example. In this embodiment, each optical unit is a PET film having a thickness of 0.025 mm on which 100 optical fiber strands (a general optical fiber coated with an ultraviolet curable resin on an outer diameter of 250 μm) are mounted. The wrapped structure is one unit, and six optical units are twisted together (the structure shown in FIG. 1). Each optical unit has a sector shape in which a circle is divided into six by the method described above.

As a comparative example, similarly, a 100-fiber optical fiber and a water-absorbing yarn for water stoppage were mounted in a circular shape, and a structure in which six optical units were twisted together (structure shown in FIG. 3). The number of optical fibers mounted in each optical unit was 10 / mm ² for all. The area where the optical fiber is mounted is an important parameter that affects the characteristics of the optical fiber, particularly the transmission characteristics, and excessive reduction in the area causes an increase in loss due to temperature expansion and contraction of the cable. The mounted optical fiber is an optical fiber according to ITU-T G652-A.

  In each of the optical fiber cables of Examples and Comparative Examples, a plurality of optical units were assembled, and then a water-absorbing tape on which a water-stopping material was placed was used as a holding roll, and a polyethylene sheath embedded with a tensile body was applied. In the optical fiber cable of this example, the outer diameter of the cable was 7.5 mm, whereas in the structure of the comparative example, it was 8.8 mm, which was reduced by 1.3 mm compared with the comparative example structure. In the optical fiber cable of this example, as a result of carrying out the waterproof test, the length of water sent between the optical units was 60 cm. However, the optical fiber cable of the comparative example was fed full length.

  In addition, in the optical fiber cable of the comparative example, in order to eliminate the gap between the optical units, 6 units were formed into a cylindrical shape by passing a cylindrical diameter die during assembly, and the optical unit assembly outer diameter was proposed. A cable finished to 7.5 mm was made in the same manner as the structure.

  In this optical fiber cable, water transmission and waterproofing performance between the optical units was improved at 70 cm, which was almost the same as in this example, but deterioration in transmission characteristics was observed. This is due to the bending that occurs when the optical fiber in the optical unit is excessively constrained because the deformation in a locally narrow shape occurs and the shape is deformed in the longitudinal direction. There were multiple local loss increases.

  Next, the manufacturing method of the optical fiber cable of this embodiment is demonstrated, referring FIG. FIG. 4 shows an example of a manufacturing apparatus having four optical units. First, the optical fiber 1 (with water-stopping material such as water absorption yarn if necessary) is fed from the fiber delivery device 9, and a plastic film (PET fill etc.) 2 delivered from the tape delivery device 10 is vertically attached to the periphery. Thus, the circular optical unit 3 is manufactured. In order to add the film 2 vertically, the optical fiber 1 and the film 2 are passed through the film wrap part 11.

  Next, a plurality of circular optical units 3 are passed through each of the fan-shaped through holes 13 formed in the molding portion 12. Each through hole 13 is formed in a hole having the same size. The molding unit 12 is heated, and once the circular optical unit 3 is passed through the fan-shaped through hole 13, the cross-sectional shape of the optical unit 3 is fan-shaped. The optical unit 3 that has passed through the through-hole 13 is deformed from a circular cross-section into a fan cross-sectional shape, and the cross-sectional area of each optical unit 3 is the same. In addition, the molding unit 12 turns the plurality of optical units 3 into an SZ twist by alternately rotating to the right and left as indicated by the arrow X.

  And after winding the water absorption tape 6 sent out from the water absorption tape delivery device 14 around the optical unit 3 twisted together, it is torn from the strength body delivery device 15 to the strength member 7 and the tear string delivery device 16. The string 8 is supplied to the extruder 17 and the optical unit 3 is covered with the sheath 4. As a result, an optical fiber cable is manufactured in which the SZ twisted optical unit 3 is tightly adhered to the cable inner space without any gap and is covered with the sheath 4.

  In the manufacturing process described above, the film 2 is formed into a cylindrical shape in a place where the position does not change due to driving or the like, and then assembled while being formed into a final shape at the collecting portion, so that the optical fiber 1 is stably wrapped. It can be formed and assembled with the shape change in the longitudinal direction as it is. At this time, it is not a good idea to fix the film 2 with, for example, an adhesive during the first stage molding. This is because the outer circumference for obtaining the same cross-sectional area is different in the shape, for example, a cylinder and a square, as in the structure shown in the above example. The shape whose outer circumference is the shortest to obtain the same cross-sectional area is a circle. Therefore, once the film 2 is fixed in a state of being formed into a circular shape, it is difficult to form a shape that is finally deformed while ensuring the same cross-sectional area.

  The cross-sectional area on which the optical fiber 1 is mounted is a parameter that has an important influence on the final optical cable characteristics, and this control is important. When the film 2 is fixed, it is necessary to form a circular shape having a circumference that can secure a necessary cross-sectional area in a shape obtained as a final shape. However, even when the film 2 is not fixed, a desired shape and its shape can be easily obtained by adding a circular shape with a film having a width obtained by wrapping a film having a width equal to or greater than a necessary length in a shape obtained as a final shape. The necessary cross-sectional area can be obtained. Also, from the viewpoint of securing a stable shape even in the final shape and preventing the optical fiber or the like from jumping out from the inside, the width of the film 2 is long with respect to the necessary peripheral length, and the wrap portion is not observed when the cross section is observed. It is desirable that the degree of occurrence is greater than the desired circumference x 1.1.

  As described above, according to the method of manufacturing the optical fiber cable of the present embodiment, the cross-sectional shape of the optical unit 3 is deformed while being heated when the plurality of optical units 3 are gathered once from the circular optical unit 3. Then, the optical unit 3 can be deformed into a desired cross-sectional shape without damaging the optical fiber 1 covered with the film 2. In addition, according to the manufacturing method of the present invention, the mounting density of the optical fibers 1 in the cable can be increased if the cross-sectional areas of the respective optical units are made the same and are closely adhered to the space in the cable without being spaced apart and accommodated in the sheath. Can do.

  Although specific embodiments to which the present invention is applied have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made. For example, a plurality of optical units 3 in the cable are arranged in the circumferential direction with the cable center as an axis in a cross section orthogonal to the cable longitudinal direction, and a plurality of optical units arranged in the circumferential direction in the cable radial direction are stacked. It may be.

  For example, as shown in FIG. 5, the optical unit 3A having a circular cross section at the center of the cable and a fan shape 5 having an arc length that divides the outer peripheral length of the optical unit 3A into five equal parts. This is an optical fiber cable having a two-layer structure in which two optical units 3B to 3F are arranged in the circumferential direction.

  The cross-sectional area of the circular optical unit 3A and the cross-sectional areas of the fan-shaped optical units 3B to 3F are all the same. Further, the circular optical unit 3A and the fan-shaped optical units 3B to 3F are in close contact with each other without any gap, and the fan-shaped optical units 3B to 3F are also in close contact with each other without any gap. In this example, there are two layers, but three or more layers may be used.

  INDUSTRIAL APPLICABILITY The present invention can be used for an optical fiber cable in which a plurality of optical units obtained by coating a plurality of optical fibers with a film are accommodated in a cable made of a cylindrical sheath.

DESCRIPTION OF SYMBOLS 1 Optical fiber 2 Film 3 Optical unit 4 Sheath 5 Cable 6 Water absorption tape 7 Strength body 8 Tear string

Claims (7)

In an optical fiber cable in which a plurality of optical units obtained by coating a plurality of optical fibers with a film are accommodated in a cable made of a cylindrical sheath,
Each optical unit housed in the cable has the same cross-sectional area and is housed in close contact with the space inside the cable without any gap. An optical fiber cable. The optical fiber cable according to claim 1,
The optical unit in the cable is arranged in the cable circumferential direction with the cable center as an axis in a cross section orthogonal to the cable longitudinal direction. An optical fiber cable according to claim 2,
Each optical unit has a fan-shaped cross section. An optical fiber cable. The optical fiber cable according to claim 1,
A plurality of optical units in the cable are arranged in the circumferential direction around the center of the cable in a cross section orthogonal to the cable longitudinal direction, and a plurality of optical units arranged in the circumferential direction in the cable radial direction are stacked. An optical fiber cable characterized by An optical fiber cable according to claim 4,
The optical unit arranged at the center of the cable has a circular cross section, and the optical units stacked on the outside have an arc length equally dividing the outer peripheral length of the optical unit having a circular cross section. An optical fiber cable characterized by a fan shape. The optical fiber cable according to any one of claims 1 to 5,
Each of the optical units is twisted so as to intersect right and left in the circumferential direction in the longitudinal direction of the cable. In the method of manufacturing an optical fiber cable in which a plurality of optical units obtained by coating a plurality of optical fibers with a film are accommodated in a cable made of a cylindrical sheath,
A plurality of optical fibers are covered with a film to form a plurality of circular optical units, and the cross-sectional area of each optical unit is made the same by changing the cross-sectional shape of the optical unit while heating the optical units during assembly. Then, the optical unit is closely attached to the space in the cable without a gap and covered with a sheath.

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