JP2000249881A - Structure of optical fiber cable - Google Patents

Abstract

PROBLEM TO BE SOLVED: To assure tensile force and shrinkage force without embedding a tension member into a sheath and to reduce the outside diameter of a cable by coating a laminate of coated optical fiber ribbons and a ribbon-like rod tension member plastic material to unitize the laminate, then housing the unit into a sheath. SOLUTION: The ribbon-like rod (tension member) 13 made of FRP is arranged at a center and the 8-core coated optical fiber ribbons 12 are laminated in the state of holding the rod with three sheets each of the coated fiber ribbons. The laminate is coated with a UV curing resin and is integrated to form the unit 15. The unit is housed into the sheath 14 of a polyethylene tube, by which the optical fiber cable of 48 cores (six sheets of 8-core ribbons) is constituted. Between the inside surface of the sheath and the unit 15 is a gap. Since the coated fiber ribbons 12 are integrated with the ribbon-like rod 13 and is reinforced, microbending hardly occurs. The ribbon-like rod 13 functions also as a resistor to the shrinkage force of the sheath 14.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a small-fiber optical fiber cable having about 200 fibers or less, and a jellyless structure for a small-fiber optical fiber cable using a tape core. Thus, the handleability can be improved, the diameter can be reduced, and the cost can be reduced.

[0002]

2. Description of the Related Art There are strong demands for low-cost and small-diameter optical fiber cables of about 200 cores or less, which are used for indoor wiring or the like. The above requirements are strong for optical fiber cables from the viewpoint of improving workability. As one of the simple ideas to meet the above requirements, as shown in FIG.
After the tape core wire 2 is placed in the center of the tube 1 and the tube 1 is filled with jelly 3,
May be covered with a sheath 5 together with a tensile strength member (FRP, steel wire, etc.) 4. However, in the case of this structure, the step of filling the tube 1 with the jelly 3 while storing the tape core wire 2 in the center of the tube 1, that is,
An optical fiber cable is manufactured by a tube forming step and a step of coating the tube 1 with the sheath 5 in a state where the tensile strength member 4 is embedded in the sheath 5, that is, a cable forming step. Since it goes against the direction of simplification and simplification and is filled with jelly, its handling is inferior in manufacturing and branching of optical fiber cables. As shown in FIG. 3, it is also conceivable that a tensile strength fiber 6 such as Kepler is longitudinally added to the tape core wire 2 and this is covered with a sheath 5 to form a cable.
However, since this structure has no bone portion, it has no resistance to the contraction of the sheath, and causes an increase in transmission loss due to the contraction force of the sheath (shrinkage due to cooling at the time of manufacture or shrinkage due to low temperature). For this reason, the inner diameter of the sheath tube must be made sufficiently large in order to avoid an increase in transmission loss due to the contraction force of the sheath, and therefore, the outer diameter of the optical fiber cable cannot be avoided. Further, as shown in FIG. 4, a structure is also conceivable in which the tape cores 2 are laminated, and when the sheath is formed, the strength members 4 are buried and covered in the sheath 5 to form a cable. With this structure, the effect on the optical fiber due to the contraction force of the sheath 5 can be suppressed, so that the loss characteristics are stabilized. However, embedding the tensile strength member 4 in the sheath requires a somewhat advanced technique in manufacturing technology. In addition, the thickness of the sheath must be relatively large, which hinders a reduction in the diameter of the optical fiber.

[0003]

SUMMARY OF THE INVENTION According to the present invention, it is possible to secure the necessary tensile strength and shrink resistance without embedding a tensile strength member in a sheath for an optical fiber cable having a small number of cores using a tape. An object of the present invention is to devise the structure so that the outer diameter can be made as small as possible.

[0004]

Means taken to solve the above problem is to collectively laminate an optical fiber tape core wire and a tape-shaped tensile strength member, coat the laminated body with a plastic material, and form a unit. This is housed in a sheath through a gap to form a cable.

[0005]

[Function] An optical fiber tape core and a tape-shaped strength member are collectively laminated, and this is coated with a plastic material and integrated into a sheath and housed in a sheath. It is integrally connected with the optical fiber ribbon. Therefore, the elongation of the optical fiber ribbon due to the tension is suppressed by the tape-shaped tensile member. In addition, since the tape-shaped strength member functions as a resistor against the contraction force of the sheath, and a gap is interposed between the sheath and the unit of the laminate, the contraction force of the sheath at the time of manufacturing or at a low temperature is reduced. It does not act on the tape core wire, so that the loss characteristics do not increase due to the contraction of the sheath, and the loss characteristics are stabilized. In addition, since the optical fiber ribbon is integrated with and reinforced with the tape-shaped tensile member, microbends are unlikely to occur, and therefore, transmission loss due to the bends is suppressed.

[0006]

Embodiment 1 Next, an embodiment will be described with reference to FIG. Example 1 shown in FIG. 1 has three 8-core tape core wires 12 each having a thickness of 0.3 mm and a width of 2.2 mm, each having a thickness of 1 mm and a width of 2.2 mm.
The tape rod 13 made of RP is laminated above and below the tape rod 13, that is, the tape rod 13 is placed at the center, and
The sheets are laminated while being sandwiched between the tape cores 12 and coated with an ultraviolet curable resin to be integrated into a unit 15 having an outer diameter of 4 mm. Heart (6 pieces of 8-core tape)
Of the optical fiber cable. The sheath 14 has an inner diameter of 5 mm and an outer diameter of 9 mm. There is a gap between the inner surface of the sheath and the unit 15. Loss test, loss temperature characteristic test (−30 ° C. to + 60 ° C.) for the optical fiber cable of Example 1,
A tensile test was performed. As a result, both the loss and the loss temperature characteristics after the cable were formed were such that the loss increase was 0.1 dB / Km or less (wavelength: 1.55 μm), and the tensile test result at a tensile force of 50 kg showed that the elongation of the cable was 0.5%. %, The loss increase was 0.00 dB / Km. This level of resistance is sufficient as an optical fiber cable for on-premise wiring. If a higher tensile strength is required, the diameter of the tape-shaped rod 13 may be increased or a plurality of tape-shaped rods may be inserted.

[0007]

Comparative Example In this comparative example, a cable having the same number of cores and dimensions as in Example 1 was used without using an FRP rod but instead filled with aramid yarn as a tensile member. They have the same cross-sectional structure. As for the test results, loss after cable conversion and tensile strength are not particularly different from those in Example 1, but a loss temperature characteristic test showed a loss of about 0.3 dB / Km at -30 degrees Celsius. Speaking of the relationship with this comparative example, it is clear that Example 1 is excellent in loss temperature characteristics.

[0008]

As described above, according to the present invention, it is possible to secure necessary tensile strength and shrinkage resistance without embedding a tensile strength member in a sheath for an optical fiber cable having a small number of cores using a tape core wire. Can be made as small as possible, so that the sheath can be simply and easily covered, and the thickness of the sheath can be minimized. Therefore, the sheath material can be saved, and the cable diameter can be reduced by the amount that the sheath thickness can be reduced. further,
Since there is no need to fill the sheath with jelly, fiber, etc., the sheath inner diameter can be reduced by that much, and the handling of the optical fiber cable branching operation is excellent, and the branching operation can be performed efficiently. . In addition, the optical fiber ribbon is coated with a plastic material in a state of being laminated together with the tape-shaped strength member, and is unitized with the tape-shaped strength member. There is no transmission loss due to bending.

[Brief description of the drawings]

FIG. 1 is a sectional view of an embodiment of the present invention.

FIG. 2 is a sectional view of a conventional example filled with jelly.

FIG. 3 is a cross-sectional view of a conventional example filled with tensile strength fibers.

FIG. 4 is a cross-sectional view of a conventional example in which a tensile material is provided inside a sheath.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Tube 2, 12 ... Tape core wire 3 ... Jerry 4 ... Tensile material 5 ... Sheath 6 ... Tensile fiber 13 ... Tape rod 14 ... Sheath 15. ..Units of tape core and tape rod

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor: Shin Saito 1440, Mukurosaki, Sakura City, Chiba Prefecture Inside Fujikura Sakura Factory (72) Inventor: Suehiro Miyamoto 1440, Misaki, Sakura City, Chiba Prefecture Inside Fujikura Sakura Factory ( 72) Inventor Masao Tatekura Nippon Telegraph and Telephone Corporation, 3-19-2 Nishi Shinjuku, Shinjuku-ku, Tokyo (72) Inventor Shigenori Uruno Nippon Telegraph and Telephone Corporation, 3-19-2 Nishi-Shinjuku, Shinjuku-ku, Tokyo F term (reference) 2H001 BB01 BB16 DD03 KK08 KK17

Claims (3)

[Claims] 1. An optical fiber cable having a small number of cores made of a tape, wherein the optical fiber tape and a tape-shaped tensile member are collectively laminated, and the laminated body is coated with a plastic material to form a unit. Of an optical fiber cable in which a cable is housed in a sheath via a gap to form a cable. 2. The tape-shaped tensile strength member according to claim 1,
Of optical fiber cable with tape-shaped rod made of steel. 3. An optical fiber cable comprising the coating material according to claim 1 or 2 as an ultraviolet curing resin.