JP2000081553A - Optical unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the coated optical fiber taking-out performance and side pressure resistance at a terminal together with laying performance when an optical unit is fed and laid into a pipeline by using air flow. SOLUTION: The structure, in which a foamed resin 3 existing in the spacing parts of wires arranged on the outermost periphery of an assemblage of the wires consisting of plural pieces of the coated optical fibers 2 or the coated optical fibers 2 and intervening wires bulges toward the outer side to form a major diameter part 4 and the foamed resin 3 in the middle of this major diameter part 4 forms a minor diameter part 5, is adopted as the structure of the optical unit having the assemblage described above and a sheath consisting of the foamed resin 3 with which the outer periphery of the assemblage is directly coated. As a result, the laying of the unit to the long-sized pipeline is made possible and the minor diameter part 5 tears easily and, therefore, the foamed resin 3 may be easily removed and the taking out of the coated optical fibers 2 is made simple. In addition, the major diameter part 4 acts as a buffer layer with respect to side pressures and, therefore, the excellent side pressure resistance is the obtained and the gripping and fixing of the terminal is facilitated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of an optical unit which is installed in a pipeline by using an airflow.

[0002]

2. Description of the Related Art With the spread of the use of optical communication technology, as a technology for easily and economically laying an optical fiber, a small-diameter pipe or a pipe cable in which small-diameter pipes are assembled is laid beforehand. Bron fiber technology in which a series of pipes are constructed by connecting pipes as necessary, etc., and optical units in which optical fibers coated with optical fibers are assembled are sent using airflow and laid without connection It has been known. The advantage of this method is that when an optical communication network becomes necessary, the required number of optical fibers can be installed in the required places without connecting the optical fibers, thus reducing initial investment and reducing installation equipment. The operation rate can be increased.

[0003] This optical unit is designed as a standard product.
4 (A) is a sectional view in which optical fibers 41 as shown in the sectional view are assembled to form a wire rod aggregate, an inner layer coating 43 is applied with an extrusion molding material such as nylon, and an outermost covering is coated with a foamed resin 42. Those having a circular outer periphery are generally used. On the other hand, as an optical unit structure for extending the laying distance, an optical unit having a groove 46 along the length direction in a jacket as shown in the sectional view of FIG. I have.

[0004]

When this type of optical unit is used, it is easy to take out the optical core wire 41 of about 50 cm required for connection at the terminal as well as the long possible installation distance. It is important that there is. In addition, it is necessary that the transmission characteristics of the optical unit be stable with respect to the lateral pressure applied from the outer periphery when fixing or gripping such as storage in a box. However, in the standard product, as shown in FIG. 4A, an inner coating 43 made of nylon or the like is coated around the optical core assembly 43, and the inner coating 43 is removed while preventing the optical core 41 from being damaged. The work was complicated. The optical unit shown in FIG. 1B, which is known as a structure for extending the installation distance, is covered with the foamed resin 45 irrespective of the surface shape of the aggregate of optical fibers, and the thickness of the foamed resin 45 increases in a short cycle. Change. Therefore, when the foamed resin 45 is removed, the optical fiber 41 is frequently broken, and the work of taking out the optical fiber 41 is complicated, and when a force for tightening from the surroundings is applied when the terminal is fixed or gripped, the optical fiber 41 is removed. A large force is locally applied to a portion located immediately below the convex portion of the foamed resin 45, and the optical core 41 is bent, resulting in deterioration of transmission loss.

[0005]

SUMMARY OF THE INVENTION The present invention comprises an aggregate of a plurality of optical fibers or a wire rod composed of an optical fiber and an intervening wire, and a foamed resin jacket directly coated on the outer periphery of the aggregate. The foamed resin jacket located in the gap between the wires located in the outermost layer of the optical unit constitutes a long-diameter portion in which the outer diameter of the optical unit swells outward, and the outer diameter of the foamed resin located in the middle of the long-diameter portion is increased. The optical unit is characterized by forming a short diameter portion having a small outer diameter of the optical unit. Further, in the present invention, the aggregate of the wires includes a center intervening line and a plurality of wires having substantially the same outer shape arranged point-symmetrically on the outer periphery thereof, wherein the wire is an optical fiber or a wire composed of an optical fiber and an intervening wire Can be used. That is, the outer periphery of the cross section of the foamed resin layer of the optical unit of the present invention repeats gradual irregularities, and the portion located outside the gap of the wire rod forming the inner aggregate bulges outward to form a long diameter portion, and the optical unit has A line connecting the centers of the individual optical fibers from the center is extended to form a short diameter portion where the distance between the center of the optical unit and the outer periphery of the foamed resin coating is short at a portion intersecting the outer periphery of the foamed resin coating.

With such a structure, the surface area of the outer casing of the optical unit is increased, friction with the gas flow is increased, and a larger traction force is obtained. This has the effect that the gas flow flows in between the optical units and the optical unit rises, and the apparent friction decreases, so that the installation distance can be increased.

On the other hand, a line extending from the center of the optical unit to the center of each optical fiber is extended to form a short-diameter portion where the distance between the center of the optical unit and the outer periphery of the foamed resin coating is short at a portion intersecting with the outer periphery of the foamed resin coating. Since the structure is formed and the coating thickness of the foamed resin is thin, the thin portion is easily cut by pulling the coating in two directions at the end, and the optical fiber can be easily taken out. In addition, since this part is thin and just outside the optical fiber, the optical fiber is pulled outward like a tear cord, so that the foamed resin jacket can be easily cut at this short diameter part and cut with a small force As a result, the optical fiber used for tearing is not damaged.

Further, when the terminal is gripped and fixed by applying a force from the outer periphery, the gripping force from the outside is received by the long diameter portion, and immediately below the gap is the optical fiber gap. Has a large effect as a buffer layer, and the effect on the transmission characteristics of the optical fiber can be reduced. Similarly, it has more stable performance against external side pressure than the conventional one. In addition, the long diameter portion and the short diameter portion are formed corresponding to the shape of the outer surface of the inner wire aggregate, and the change in the length direction of the thickness of the foamed resin around the optical core wire is small. Local bending of the optical fiber core due to the applied lateral pressure hardly occurs, and stable transmission characteristics can be obtained.

Therefore, as compared with the conventional structure, it is possible to obtain an optical unit which is excellent in the optical fiber lead-out property at the terminal and has excellent lateral pressure characteristics.

[0010]

FIG. 1 shows an embodiment of the present invention.
This will be described with reference to FIG. The optical unit 1 is formed by covering a wire assembly formed by assembling a plurality of optical fibers 2 with a foamed resin 3, and a gap between the plurality of optical fibers 2 located on the outer periphery of the wire assembly. The major diameter portion 4 is formed in the longitudinal direction corresponding to the outside of the optical fiber, extends a line connecting the center of each optical fiber 2 from the center of the optical unit, and intersects the outer periphery of the foamed resin coating 3, that is, a portion of the foamed resin coating. A short diameter portion 5 having a short distance between the center of the optical unit and the outer periphery of the foamed resin coating is formed in a portion corresponding to a middle of the long diameter portion 4 on the outer circumference. By alternately providing the long diameter portions 4 and the short diameter portions 5 in this manner, the outer surface of the optical unit becomes large. In addition, it has a structure in which the short diameter portion is located immediately outside the optical fiber continuously in the length direction, the foam resin coating just outside the optical fiber is thin and easy to tear, and the lateral pressure is the long diameter portion made of foam resin. 4, the influence on the optical fiber is reduced.

Here, the optical fiber is not limited to a single optical fiber having one optical fiber therein but also to a tape optical fiber 22 shown in FIG.
Can be used. In addition, as long as a wire aggregate can be formed, different types of optical fibers such as a multi-mode fiber and a single-mode fiber may be used in combination with the intrinsic optical fibers. It is also possible to use plastic fibers. In addition, as a wire constituting the wire assembly used here, not only the optical fiber, but also a function to stabilize the arrangement of the wires, and to manufacture an optical unit at a lower cost than when using the optical fiber, Intervening wires having substantially the same outer shape and cheaper than the core wire may be mixed. As such an intervening wire, a small-diameter rod of polyester or the like can be used. In addition, use the intervening wire whose perimeter length is selected as the central intervening line so that the arrangement of the optical core wires arranged around is stable, and twist the optical core wire, or the optical core wire and the intervening wire around it, etc. They can be arranged to form a wire aggregate.

[0012]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, which do not limit the scope of the present invention. (Embodiment 1) FIG. 1A is a cross-sectional view of an optical unit according to an embodiment of the present invention. In the figure, 1 is an optical unit, 2 is an optical fiber, and 3 is a foamed resin.

The seven optical fibers shown in FIG.
It is a single-mode optical fiber having an outer diameter of 250 μm, in which a silica glass fiber having a cladding diameter of 125 μm is coated with an ultraviolet-curable resin. These optical fibers 2 were arranged at one center and six perimeters to form a stranded wire assembly at a pitch of 300 mm, and the periphery thereof was covered with foamed polyethylene as a foamed resin 3. The outer diameter of the foamed resin layer is 1.4 mm at the maximum part and 1.0 mm at the minimum part, and six outer peripheral parts of the optical unit correspond to the outer parts of the six optical core wires on the outer periphery of the wire rod assembly. The long diameter portion 4 is formed in a spiral shape in the longitudinal direction, and a middle portion of each long diameter portion 4 forms a short diameter portion 5.

A method of manufacturing the optical unit will be described. In the covering step of foamed polyethylene, the inner diameter of the outlet is 0.9.
Using a die having a diameter slightly larger than the maximum outer diameter of the wire assembly of 5 mm and 0.75 mm, the difference in flow path resistance between the gap between the outer optical fibers and the outer portion of the optical fibers is increased, and 6
A large amount of resin was allowed to flow to the portion of the optical fiber core located in the gap, and the optical unit was formed so that the outer periphery of the optical unit had irregularities bulging outside the optical core gap at the die exit. Further, in the subsequent cooling step, the surface of the optical unit immediately after leaving the dice is cooled at room temperature, and the foaming resin having a thin coating located outside the outer optical core wire is rapidly cooled to suppress foaming, while having a large heat capacity. The foam coating located in the gap between the optical fibers was foamed larger. FIG. 1 (B) is FIG. 1 (A)
It is a figure which showed typically the foaming state of the foaming resin of the range of the angle PQR in the cross section of FIG.
The foamed resin bubbles inside the long diameter portion 4 became larger than the short diameter portion 5, and an optical unit having a large difference in distance between the long diameter portion 4 and the short diameter portion 5 from the center of the optical unit could be manufactured.

This optical unit is 4.5 mm in inner diameter and 1 mm long.
As a result of conducting an experiment in which air was passed through a 000 m polyethylene pipe using 4 atm of compressed air, it was confirmed that the entire length could be sent in 30 minutes, and good laying performance was provided. In this optical unit, the portion of the short diameter portion 5 can be continuously cut over 500 mm in the longitudinal direction by pulling the jacket in two directions with the fingers at the terminal, and the optical core including the extra length necessary for connection is taken out. Was easy. Further, by pulling one optical core wire 2 outward, the cutting of the foamed resin jacket can be easily generated at the short diameter portion 5, and the force required at this time is small, and the colored layer is broken. No abnormalities occurred in the transmission characteristics of the optical fibers.

Next, the optical unit is passed through the center hole of a cylindrical rubber bushing having a length of 15 mm and an outer diameter of 6 mm using a rubber having a hardness of Shore A60 according to a general terminal processing method of this type of optical unit. Simulating the fixing, a lateral pressure was applied to the outer periphery of the rubber bushing to tighten the optical unit. Even when a lateral pressure of 20 kg was applied, no change in the transmission loss of all the optical fibers in the optical unit was observed below the measurement limit of 0.05 dB, and stable performance was confirmed.

Comparative Example FIGS. 4A and 4B are cross-sectional views of two types of optical units manufactured as comparative examples. Each of the optical units has an outer diameter of 250 μm, which is the same as in the first embodiment.
Of single-mode optical fibers 41 are provided, and colored layers of different colors are provided on the outermost layer, and are distinguishable from each other.

FIG. 4 (A) shows an optical fiber 41 arranged at one center and six circumferences, twisted and assembled at a pitch of 300 mm.
An optical unit having an outer diameter of 1.6 mm formed by extruding nylon to form an inner layer coating 43 having an outer diameter of 0.9 mm, and then coating the expanded resin with a foamed polyethylene. Since this optical unit has a sticky nylon inner coating 43, it cannot be torn with fingers, and a knife is required to take out the optical fiber, and the nylon inner coating 43 is removed so as not to damage the optical fiber. The work to do was complicated. An experiment was conducted in which the optical unit was passed through a polyethylene pipe having an inner diameter of 4.5 mm and a length of 1000 m using compressed air of 4 atm. As a result, the optical unit stopped at 700 m.

FIG. 4B shows an optical fiber 41 similar to that of the first embodiment.
Are arranged in one center and six perimeters, twisted and gathered at a pitch of 300 mm, and foamed resin 4 made of foamed polyethylene
5 was coated using a star-shaped die having eight grooves, and the maximum outer diameter of the foamed resin 45 was 1.4 mm and the groove depth was 0.20 mm.
It is an optical unit. An experiment was conducted in which the optical unit 44 was passed through a polyethylene pipe having an inner diameter of 4.5 mm and a length of 1000 m using compressed air of 4 atm. As a result, the entire length could be sent in 35 minutes, and the installation characteristics were good. However, when the optical fiber 41 is taken out at the terminal, the foamed resin 45 is torn by a finger at the terminal part, but when the length of several cm is torn, the foamed resin 45 is torn off, and it is necessary to remove the coating again from that position. The operation of taking out the cord 41 was very complicated. This is because the shape of the groove 46 engraved on the outer periphery of the foamed resin 45 and the shape of the depression 46 on the inner wall of the foamed resin 45 that reflects the shape of the optical fiber aggregate is irrelevant, so that the coating extends along the groove 46 on the outer periphery. This is because stress is concentrated on a locally thin portion without being cut in the direction. Next, in the same manner as in Example 1, the optical unit was passed through the center hole of a cylindrical rubber bushing having a length of 15 mm and an outer diameter of 6 mm. When a lateral pressure of 10 kg was applied, the two optical fibers in the optical unit showed a transmission loss increase of 0.3 dB. This is foam resin 4
Since the shape of the recessed portion 47 of the foamed resin inner wall that reflects the shape of the aggregate of the optical fiber 41 and the groove 46 engraved on the outer periphery of 5 is irrelevant, the convex portion of the foamed resin 45 that has been subjected to the lateral pressure from the outside is immediately This is because a large lateral pressure is transmitted when there is an optical fiber below.

(Embodiment 2) FIG. 2 is a sectional view of an optical unit for explaining a second embodiment of the present invention.
In the figure, 21 is an optical unit, 22 is an optical fiber, 23 is a foamed resin, and 24 is a center interposition line.

The four optical fibers 22 shown in FIG.
This is a two-core tape type optical fiber having a diameter of 5 mm and a minor diameter of 0.4 mm.
Each of these two-core tape type optical fibers 22 has a core diameter of 10 μm.
m, two single-mode optical fibers each having an outer diameter of 250 μm obtained by coating a silica glass fiber having a cladding diameter of 125 μm with an ultraviolet-curable resin are integrated with a tape coating material made of an ultraviolet-curable resin. These optical fibers 22
Is a center interposed line 2 made of polyester resin having an outer diameter of 0.5 mm.
4 were arranged around the wire 4 to form a stranded wire assembly at a pitch of 400 mm, and foamed polyethylene was coated as the foamed resin 23. The outer diameter of the foamed resin 23 is 2.0 m at the maximum.
m, which is 1.5 mm at the minimum part, and four long diameter portions 2 on the outer periphery of the optical unit 21 corresponding to the outside of the gap portion of the optical core wire 22.
5 are spirally formed in the longitudinal direction, and a middle portion of each long diameter portion forms a short diameter portion 26. As in the case of Example 1, good laying characteristics, good take-out property of the tape-type optical fiber 22 and stable transmission characteristics with respect to lateral pressure were confirmed for the optical unit 21 as well.

(Embodiment 3) FIG. 3 is a sectional view of an optical unit for explaining a third embodiment of the present invention.
In the figure, 31 is an optical unit, 32 is an optical fiber, and 33 is a foamed resin. 34 is a polyester yarn added as an intervening wire.

The two optical fibers 32 shown in FIG.
μm, a single-mode optical fiber having an outer diameter of 250 μm obtained by applying a UV curable resin coating to a single-mode fiber having a cladding diameter of 125 μm, and twisted and assembled with two polyester yarns 34 having the same outer diameter as the optical fiber, An optical unit was formed by covering foamed polyethylene as the foamed resin 33.
The outer diameter of the foamed resin 33 is 1.1 mm at the maximum part and 0.75 mm at the minimum part, and four major diameter parts are provided on the outer periphery of the optical unit 31 corresponding to the outside of the gap between the optical core 32 and the interposed wire 34. 35 are spirally arranged in the longitudinal direction, and a middle portion of each long diameter portion forms a short diameter portion 36. As in the case of Example 1, good laying characteristics, good take-out of the optical fiber, and stable transmission characteristics with respect to the lateral pressure were confirmed for this optical unit. In addition, since this optical unit has a small number of assembled wires, when the outer periphery is covered with a circle, the optical unit easily bends to a bending radius of 15 mm or less around a line connecting opposing optical fiber gaps, and loss is likely to increase. But
In the optical unit of the present invention, since a large amount of foamed resin is present in the gap between the optical fiber and the intervening wire, the resistance to bending is increased, and the resistance to bending can be improved.

[0024]

As described above, according to the configuration of the present invention, it is possible to obtain an optical unit having excellent laying distance, optical core wire take-out property, and lateral pressure characteristics. For this reason, it is effective when used for an application such as an optical LAN where the optical fiber is frequently connected.

[Brief description of the drawings]

FIG. 1A is a first embodiment of an optical unit according to the present invention.
It is a schematic diagram which shows the cross section. (B) is a diagram illustrating the structure of the foamed resin of Example 1 of the optical unit.

FIG. 2 is a schematic view illustrating a cross section of an optical unit according to a second embodiment of the present invention.

FIG. 3 is a schematic diagram illustrating a cross section of a third embodiment of the optical unit according to the present invention.

FIG. 4 is a schematic view showing a cross section of a comparative example for explaining the effect of the present invention.

[Explanation of symbols]

 1: Optical unit 2: Optical core wire 3: Foam resin 4: Long diameter part 5: Short diameter part 6: Bubbles 21: Optical unit 22: Optical core wire 23: Foam resin 24: Center interposed line 25: Long diameter part 26: Short Diameter part 31: Optical unit 32: Optical core wire 33: Foam resin 34: Intervening wire 35: Long diameter part 36: Short diameter part 40: Optical unit 41: Optical core wire 42: Foam resin 43: Inner layer coating 44: Optical unit 45 ： Foam resin 46 ： Groove on the outer circumference 47 ： Indentation of foam resin inner wall

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Hiroaki Sano 1-chome, Taya-cho, Sakae-ku, Yokohama-shi, Kanagawa F-term (reference) in Yokohama Works, Sumitomo Electric Industries, Ltd. 2H001 BB02 BB06 BB25 KK17 2H050 BB03R BB10S BB33Q BB42S BC11 BD00

Claims (2)

[Claims] 1. An assembly comprising a plurality of optical fibers or an assembly of wires composed of optical fibers and intervening wires and a foamed resin jacket directly coated on the outer periphery thereof, and a wire arranged on the outermost periphery of the assembly An optical unit, wherein the foamed resin jacket located in the gap portion of the optical unit has a long diameter portion bulging outward, and the foamed resin jacket in the middle of the long diameter portion has a short diameter portion. 2. The wire assembly comprises a center intervening line and a plurality of wires of substantially the same outer shape arranged point-symmetrically around the center intervening line, and the wire comprises an optical core line or an optical core line and an intervening line. The optical unit according to claim 1, wherein