JP2585393Y2 - Protection structure for non-metallic optical cable - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a protection structure for a non-metallic optical cable which is easy to carry and does not apply tension to the non-metallic optical cable.

[0002]

2. Description of the Related Art An optical fiber communication system has been put to practical use in various fields by utilizing its characteristics such as non-induction, wide band, and low loss. The required number of optical fibers are coated and twisted to form an optical cable, and this optical cable is combined with an existing transmission line or buried in the ground. By the way, non-metallic optical cables that do not use metal as the covering material are used in lightning-damaged areas.However, because they do not use metal, their strength is low. Protecting. As shown in FIG. 4 (a), the non-metallic optical cable protected by the above-mentioned plastic pipe includes a non-metallic optical cable 1 having a required number of optical fibers put in an FRP pipe 7 and a gap filled with an FRP rod 8, As shown in FIG. 4 (b), there was a non-metallic optical cable having a non-metallic optical cable 1 in which an HDPE (high-density polyethylene) pipe 9 was inserted.

[0003]

However, since the diameter of the above-mentioned non-metallic optical cable with a pipe is large, the winding amount of the drum is small and the transportation cost is high. Also, since the outer plastic pipe is a continuous body, tension is applied to the non-metallic optical cable due to the difference in thermal expansion between the outer pipe and the inner non-metallic optical cable, resulting in distortion of the optical fiber and high optical transmission. There was a problem that characteristics could not be obtained.

[0004]

Means for Solving the Problems The present invention has been made as a result of intensive research in view of such a situation, and its purpose is to reduce the transportation cost and to apply tension to the non-metallic optical cable in use. An object of the present invention is to provide a protection structure for a non-metallic optical cable that does not hang. That is, the present invention is a protection structure in which a short plastic cylinder is continuously covered on the outer periphery of a non-metallic optical cable, and the plastic cylinder has a notch extending from the surface to an internal through hole. It is characterized by being formed over the entire length in the direction.

[0005] In the present invention, in order to cover a non-metallic optical cable with a short plastic tubular body having a cutout (hereinafter referred to as a protective pack), the cutout of the protective pack is widened and fitted from the side. After inserting the non-metallic optical cable, the notch is closed to protect the non-metallic optical cable from external pressure over the entire circumference. Therefore, the protective pack is made of a plastic material which opens and closes the notch within the elastic deformation, is not underground and corrodes, and withstands underground pressure. Specifically, polyvinyl chloride resin, polyethylene resin and the like are suitable.

The cross-sectional shape of the outer periphery of the protective pack is arbitrary, such as square or round. The shape of the through-hole may be any shape as long as it can hold the non-metallic optical cable. The thickness of the protective pack is determined by the embedding conditions and the strength of the material used. The notch of the protective pack should be straight in both cross-section and axial direction, and the shortest part in the cross-sectional direction, that is, the part where the thickness of the protective pack is the smallest, is easy to manufacture the protective pack and fit the non-metallic optical cable. This is preferable. When the length of the protective pack is about 1 m, it can be easily transported and fitted into a cable.

[0007]

[Function] The protective structure of the present invention is a non-metallic optical cable covered with a protective pack (a short plastic tube with a cutout), so that the protective pack can be fitted just before embedding the non-metallic optical cable. It is possible. Therefore, when transported to the site, a large number of small-diameter non-metallic optical cables can be wound around the drum, and the protective pack used as the exterior can be compactly packed, so that the transportation cost is reduced. In addition, since the protection structure of the present invention is a non-metallic optical cable that is continuously covered with a short protection pack, the difference in thermal expansion between the protection pack and the non-metallic optical cable is absorbed by the gap between the protection packs. Tension is less likely to be applied to the metallic optical cable.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to embodiments. FIG. 1 is a perspective view showing an embodiment of the protection structure of the present invention. Reference numeral 1 denotes a non-metallic optical cable, and reference numeral 2 denotes a protective pack to cover the non-metallic optical cable. The protective pack 2 is continuously covered on the non-metallic optical cable 1. The protective pack 2 has a rectangular outer peripheral cross section and a through hole 3 having a circular cross section inside. A notch 4 reaching the through hole 3 is formed in one side of the outer periphery of the protective pack 2 in a straight line over the entire length of the protective pack 2 in the axial direction. The protection pack 2 is expanded from the notch 4 and fitted from the side of the non-metallic optical cable 1. After the fitting, the notch 4 is closed and the non-metallic optical cable 1 is protected over the entire circumference.

FIGS. 2A and 2B are a side view and a cross-sectional view, respectively, showing a situation in which the non-metallic optical cable having the protection structure of the present invention is buried underground. The non-metallic optical cable 1 is pulled out from the drum 5 and, at the drawn-out portion,
The protective pack 2 is sequentially fitted and covered, and the non-metallic optical cable 1 in which the protective pack 2 is fitted is disposed at the bottom of the groove 6 dug underground.

FIGS. 3 (a) and 3 (b) are longitudinal and transverse sectional views, respectively, showing a state in which a non-metallic optical cable is buried underground in the protection structure of the present invention. Non-metallic optical cable 1
However, it is buried in the ground by continuously covering short protective packs 2. The thermal expansion and shrinkage of the protective pack 2 is
The tension is not applied to the non-metallic optical cable 1 by being absorbed in the gap between them.

[0011] The non-metallic optical cable and the protective pack were carried to the site by truck. The non-metallic optical cable was wound around the drum and placed in the center of the truck bed, and the protective pack was compactly stacked around the drum. As the drum, the same drum as that used in the conventional pipe-covered optical cable was used. Since the non-metallic optical cable has a small diameter, it can be wound three times as long as a conventional pipe-covered optical cable. In addition, the non-metallic optical cable buried underground has provided excellent optical communication for a long time.

[0012]

[Effect] As described above, according to the protection structure of the present invention, since the protection pack can be put on the site, a large number of small-diameter non-metallic optical cables can be wound around the drum and transported to the site. Costs are reduced. Also, the difference in thermal expansion between the protective pack and the non-metallic optical cable is absorbed by the gap between the protective packs, and no tension is applied to the non-metallic optical cable, so that good optical communication can be realized for a long time.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an embodiment of a protection structure according to the present invention.

FIGS. 2A and 2B are a side view and a cross-sectional view showing a state where a non-metallic optical cable is buried underground in the protection structure of the present invention.

FIG. 3 is a vertical and horizontal sectional view showing a state in which a non-metallic optical cable is buried underground in the protection structure of the present invention.

FIG. 4 is a cross-sectional view of a conventional pipe-covered non-metallic optical cable.

[Description of Signs] 1 Non-metallic optical cable 2 Protective pack 3 Through hole 4 Notch 5 Drum 6 Underground groove 7 FRP pipe 8 FRP rod 9 HDPE pipe

Claims (1)

(57) [Scope of request for utility model registration] 1. A protection structure comprising a non-metallic optical cable and a short plastic tubular body continuously covered on an outer periphery thereof. A non-metallic optical cable protection structure characterized by being formed over the entire length.