JP2001343565A - Optical cable - Google Patents

Abstract

PROBLEM TO BE SOLVED: To impart satisfactory water proof to an optical cable having such a structure that yarn is assembled around a coated optical fiber tape, a sheath is covered on the yarn and a tension member and tear strings are housed into the sheath. SOLUTION: A water absorptive tape 11 is vertically attached and disposed between the yarn 2 and the sheath 3 or water absorptive powder is attached on the surface of the coated optical fiber tape.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical cable having excellent waterproof properties.

[0002]

2. Description of the Related Art Recently, an optical cable having a structure as shown in FIG. 7 has been proposed. In FIG. 7, reference numeral 1 denotes an optical fiber ribbon assembly. The optical fiber ribbon assembly 1 is, for example, formed by laminating about 5 to 6 optical fiber ribbons in a twisted or straight form. Around the optical fiber ribbon assembly 1, a yarn 2 functioning as an intermediary around the assembly 1.
Are gathered to form an optical cable core having a circular cross section with a diameter of about 3 to 10 mm. This yarn 2
It is made of a single fiber having a small diameter such as polyester fiber or aramid fiber, or made of a polypropylene split fiber.

[0003] A sheath 3 made of polyethylene, plasticized polyvinyl chloride or the like is coated around the optical cable core by an extrusion coating method. Inside the sheath 3 are two tension members 4 and 4 made of a steel wire or the like having a diameter of about 0.4 to 2.0 mm, and a diameter of 0.5 to 2.0 mm.
Two tear cords 5 and 5 of about 2.0 mm made of a nylon string, a polyester string, or the like are arranged and provided so as to pass each other. In addition, sheath 3
Due to the presence of the tear cords 5 and 5 having a slightly larger diameter, the portion has a shape which expands outward like a bump.

In an optical cable having such a structure,
Since the tear string 5 is provided inside the sheath 3, when the middle rear branch of the optical fiber cable is performed, the tear string 5 is used.
By tearing, the sheath 3 can be easily removed, and since there is no hold-up winding for winding the optical cable core, the optical fiber ribbon can be easily taken out from the optical cable core, and the work required for the intermediate rear branching Time can be reduced.

However, such an optical cable can be used in an aerial environment such as an aerial wiring, but has a problem in that it has an insufficient waterproof function and cannot be used, for example, in an underground cable such as a tunnel. there were.

[0006]

Accordingly, an object of the present invention is to provide an optical cable having the structure shown in FIG. 7 with a waterproof function so that it can be used as an underground cable or the like.

[0007]

The object of the present invention is achieved by providing a water-absorbing tape vertically between the yarn and the sheath of the optical cable, or by attaching a water-absorbing powder to the optical fiber ribbon. Will be resolved. The water-absorbing tape may surround the entire circumference of the yarn or a part of the circumference of the yarn. Further, the water-absorbing powder may be intermittently attached in the longitudinal direction of the optical fiber ribbon.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
FIG. 1 shows a first example of an optical cable according to the present invention.
The same components as those shown in FIG. 7 are denoted by the same reference numerals, and description thereof will be omitted. The optical cable of this example differs from the optical cable shown in FIG. 7 in that a water absorbing tape 11 is provided between the yarn 2 and the sheath 3. The water-absorbing tape 11 is made of a highly water-absorbing resin having a water absorption of 100 to 300% such as starch or polyacrylic acid and having a thickness of 0.2 to 0.5 mm or a polyester or polypropylene having a thickness of 0.2 to 0.5. What adhere | attached the powder of 10-50 micrometers of particle diameters of the above-mentioned superabsorbent resin to the surface of a 0.5-mm film is used.

The water-absorbing tape 11 is provided so as to be vertically attached to the yarn 2 so as to surround the entire circumference of the yarn 2, and both edges of the water-absorbing tape 11 are overlapped with each other. . Further, two or more water-absorbing tapes 11 may be stacked at different positions and vertically attached, thereby shortening the water stopping distance.

FIG. 2 shows a second embodiment of the optical cable according to the present invention. In this embodiment, a water-absorbing tape 11 is attached vertically so as to cover a part of the periphery of the yarn 2. Are different from the optical cable of the first example. Therefore, the water-absorbing tape 11 needs to be narrower than the previous one, and the cost is low, but the waterproofness is inferior. However, depending on the usage of the optical cable, the optical cable may exhibit sufficient waterproofness.

FIG. 3 shows a third embodiment of the optical cable according to the present invention. In the optical cable of this embodiment, a myriad of water-absorbing powders 12 are attached to the surface of the optical fiber ribbon assembly 1. The water-absorbing powder 12 is a powder having a particle size of 5 to 50 μm, preferably 10 to 30 μm, of the above-mentioned superabsorbent resin. The amount of the water-absorbing powder 12 adhered depends on the thickness of the optical fiber ribbon core assembly 1, but it is in the range of 1 to 50 g per 1 m of the length. However, even if it exceeds 50 g, further improvement in waterproofness cannot be obtained, and it is useless.

Further, the water-absorbing powder 12 is wrapped with the yarn 2 from the outside thereof, so that the water-absorbing powder 12 does not fall off from the optical fiber core assembly 1. Further, the water-absorbing powder 12 may be attached over the entire length of the optical fiber ribbon core assembly 1 or may be attached intermittently in its longitudinal direction. In this case,
The distance between the adhering parts 50 to 1000 cm,
It is preferably 100 to 300 cm, and the length of the adhering portion is desirably 1 to 100 cm, preferably 5 to 20 cm.

In an optical cable having such a structure,
Even if the sheath 3 receives an injury or the like and water such as rainwater enters the inside, the water-absorbing tape 11 or the water-absorbing powder 12 absorbs the water and expands greatly, forming a kind of dam in the sheath 3. And further water intrusion is stopped,
The phenomenon that water runs through the optical cable is prevented, and sufficient waterproofness is exhibited.

Next, a method for manufacturing the optical cable will be described. FIG. 4 shows a method for manufacturing the first and second optical cables. First, the optical fiber ribbon assembly 1 and the yarn 2 are supplied to the yarn assembly die 13,
The yarns 2 are assembled on the optical fiber ribbon assembly 1 to form a cable core 14. Then, this cable core 1
4. A water absorbing tape 11 is attached to the extruding head 15 with the water absorbing tape 11 attached vertically, where the yarn 2 is surrounded by the water absorbing tape 11 and at the same time, the sheath 3, the tension members 4, 4 and the tear cords 5, 5 are provided thereon. Thus, a desired optical cable can be manufactured.

FIG. 5 shows a method for manufacturing the optical cable of the third example. In this method, a predetermined amount of water-absorbing powder 12 is sprayed from the water-absorbing powder supply device 16 onto the optical fiber tape core assembly 1 before the optical fiber core assembly 1 is fed into the yarn collecting die 13. , Let it adhere. At this time, the surface of the optical fiber ribbon assembly 1 is coated with a jelly or an adhesive in advance,
The adhesion of the water-absorbing powder 12 can be improved.

The optical fiber tape core assembly 1 having the water-absorbing powder 12 adhered to the surface thereof is supplied to a yarn assembly die 13 together with the yarn 2 to be a cable core 14. The cable core 14 is sent to an extrusion head (not shown), and provided with a sheath 3, tension members 4, 4 and tear strings 5, 5 in the same manner as in the previous manufacturing method.

FIG. 6 shows a modification of the method of manufacturing the optical cable of the third example. In this example, a shutter 17 for opening and closing the water-absorbing powder discharge port of the water-absorbing powder supply device 16 is provided. The water-absorbing powder 12 is intermittently sprayed by opening and closing the shutter 17 at regular time intervals, and the water-absorbing powder is intermittently applied to the surface of the optical fiber tape core assembly 1 in the longitudinal direction. 12 is attached.

The following is a specific example. An optical cable having the structure shown in FIG. 1 was produced. The optical fiber ribbon assembly 1 is made of a laminate of six four-core optical fiber ribbons, and the yarn 2 is made of a 5000 denier polypropylene split fiber fiber, and the water absorbent tape 11 is made of the same. Is a polyacrylic acid-based superabsorbent resin powder (average particle size: 20 μm) on the surface of a polyester film having a thickness of 50 μm.
m) was adhered to 100 g per 1 m ² and cut into a width of 5 mm.

The sheath 3 was made of low-density polyethylene, the tension member 4 was made of a 1.5 mm diameter steel wire, and the tear string 5 was made of a 2 mm diameter nylon string. The manufacturing method used was the method shown in FIG. 4, and the water-absorbing tape 11 was arranged such that the surface of the water-absorbing resin powder adhered to the sheath 3.

The obtained cable was evaluated for waterproofness as follows. 10 m of the optical cable is cut off, one end is sealed, and the other end is connected to one end of a 5 m long vinyl chloride resin pipe in a watertight manner. This pipe is set upright, and the pipe is filled with water. Left for one day. After the standing period, the cable was cut open, and the distance traveled by the water was measured. As a result, the running distance of the water was 15 m.

[0021]

As described above, the optical cable of the present invention has good waterproofness and can be used for applications such as underground cables. Also,
Its manufacture is easy, and effects such as its inexpensive manufacture can be obtained.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating an example of an optical cable of the present invention.

FIG. 2 is a sectional view showing another example of the optical cable of the present invention.

FIG. 3 is a sectional view showing another example of the optical cable of the present invention.

FIG. 4 is a diagram illustrating an example of a method for manufacturing an optical cable according to the present invention.

FIG. 5 is a view showing another example of the method for manufacturing an optical cable of the present invention.

FIG. 6 is a diagram showing another example of the method for manufacturing an optical cable of the present invention.

FIG. 7 is a sectional view showing a conventional optical cable.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Optical fiber tape core assembly, 2 ... Yarn, 3 ... Sheath, 11 ... Water-absorbing tape, 12 ... Water-absorbing powder

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Naoki Okada 1440, Mukurosaki, Sakura City, Chiba Prefecture Inside Fujikura Sakura Office (72) Inventor Koichiro Watanabe 1440, Musaki, Sakura City, Chiba Prefecture Inside Fujikura Sakura Office ( 72) Inventor Suehiro Miyamoto 1440 Mutsuzaki, Sakura City, Chiba Prefecture Inside Fujikura Sakura Office (72) Inventor Box ▲ Saki ▼ Dr. 2-3-1 Otemachi, Chiyoda-ku, Tokyo Nippon Telegraph and Telephone Corporation ( 72) Inventor Hideyuki Iwata 2-3-1, Otemachi, Chiyoda-ku, Tokyo F-term in Nippon Telegraph and Telephone Corporation (reference) 2H001 BB02 BB16 DD06 DD15 DD24 DD36 KK22

Claims (4)

[Claims] 1. An optical cable in which yarns are gathered around an optical fiber tape core and a sheath is coated around the yarn, wherein a water-absorbing tape is vertically attached between the yarn and the sheath. An optical cable, which is provided. 2. The yarn according to claim 1, wherein the water-absorbing tape is vertically attached to a part of the outer periphery of the yarn.
Optical cable as described. 3. An optical cable in which yarns are gathered around an optical fiber ribbon and a sheath is coated around the yarn, wherein a water-absorbing powder is attached to the optical fiber ribbon. Optical cable characterized by the following. 4. The optical cable according to claim 3, wherein the water-absorbing powder is intermittently attached in the longitudinal direction of the optical fiber ribbon.