JPH0470606B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a two-core optical fiber cable for indoor wiring and outdoor wiring.

(Prior Art) Fig. 5 shows a cross-sectional view of an example of a conventional optical fiber cable for indoor wiring, with the optical fiber 11 at the center and reinforcing cores such as steel wires and high tensile strength plastic fibers arranged concentrically around the optical fiber 11. A plurality of strips 12 are arranged, and a plastic coating layer 13 formed by extrusion coating of polyvinyl chloride or the like is commonly provided on these strips.

FIG. 6 shows a cross-sectional view of an example of a conventional optical fiber cable for outdoor wiring, in which a reinforcing layer 2 made of high tensile strength fibers such as Kepler is placed around the optical fiber 21.
The core wire 2 and the steel wire 23 are arranged in parallel at intervals, and a protective coating layer 24 formed by extrusion coating of polyvinyl chloride, polyethylene, etc. is provided on these in common, and is formed in a daruma shape.

(Problem to be solved) Both the above-mentioned optical fiber cable for indoor wiring and optical fiber cable for outdoor wiring have a structure with a single optical fiber, so transmission using such optical fiber cables is performed using the same optical fiber. It is necessary to transmit the signal separately into upstream and downstream wavelengths, which requires a multiplexer/demultiplexer.

Therefore, a single cable cannot be used for bidirectional transmission without using a multiplexer/demultiplexer, and conversely, laying two cables is uneconomical. Fiber optic cable for wiring is required.

In addition, conventional indoor and outdoor optical fiber cables cannot be used in common because their structures are completely different, and it is necessary to connect optical fibers between outdoors and indoors, which requires labor and construction costs. do.

Furthermore, in the case of optical fiber cables for outdoor wiring,
When cutting off the neck of the protective coating layer that connects the steel wire and the optical fiber, there are problems such as the need for special tools in order to avoid damaging the optical fiber.

(Means for Solving the Problems) In order to solve the above-mentioned problems, the present invention has the basic structure of optical fiber cables for both indoor and outdoor wiring. In order to prevent the optical transmission characteristics from deteriorating after installation, we constructed an optical fiber cable that is equipped with a dual-core optical fiber and can be used both indoors and outdoors. The first invention is a configuration of optical fibers common to both of the above, that is, two optical fibers arranged in parallel or in contact with each other or with a slight spacing between them. a fiber, a reinforcing core coplanarly spaced on opposite sides of the optical fiber, and an extruded plastic coating of generally circular cross section common to the optical fiber and the reinforcing core; A cable with two recesses formed on the surface of the part perpendicular to the plane formed by the optical fiber and the reinforcing core, and a cut groove facing the direction of the optical fiber at the bottom of the recess is made of steel. This is a two-core optical fiber cable that is wound around a supporting wire with a plastic coating on the outer periphery of the wire.

Further, the second invention provides a cable which is used in common with the first invention, and which has a tear string attached to one or both of the concave portions of the plastic covering layer of the cable, and a protective covering layer is provided on the outer periphery of the cable. This is a two-core optical fiber cable made of a steel wire wound around a support wire with a plastic coating on the outer periphery.

Furthermore, a third invention is a cable that is used in common with the first invention, in which a steel wire is arranged in parallel with a cable with a tear string attached to one or both of the recesses in the coating layer of the cable, and This is a twin-core optical fiber cable with a daruma-shaped plastic protective covering covering the wires.

By adopting the above configuration, the two-core optical fiber cable can be used both outdoors and indoors.

(Example) First, the structure of a two-core optical fiber cable common to the present invention will be explained with reference to FIG.

In the drawing, two optical fibers 1 are arranged in parallel or in contact with each other or with a slight spacing between them. Reinforcement cores 2 made of steel wire, high tensile strength fibers, etc. are arranged on both sides of the two optical fibers 1 at intervals and on the same plane. It is provided with a plastic coating layer 3 made of extrusion coating of vinyl chloride, polyethylene, etc. and having a substantially circular cross section. Since this is commonly used for indoor wiring and outdoor wiring, the cross section is approximately circular.

The plastic coating layer 3 includes an optical fiber 1.
Two recesses 5 are formed on the surface of the portion perpendicular to the plane formed by the reinforcing core 2, and a cut groove 4 facing toward the optical fiber 1 is formed at the bottom of the recess 5.

The purpose of the recess 5 is to provide the optical fiber cable with the bendability necessary for wiring, and
The depth of the cut groove 4 is made shallow to facilitate the formation and tearing of the cut groove. The two reinforcing cores 2 on both sides of the optical fiber 1 can withstand a certain amount of tensile force and have the function of suppressing the force that tends to shrink the plastic coating layer due to temperature fluctuations, etc., and when in use, the optical fiber Prevents changes in transmission characteristics. This optical fiber cable is for indoor use.

FIG. 1 shows a cross-sectional view of an embodiment of the first invention, in which an outdoor distribution cable is realized with the simplest structure.

In this embodiment, the indoor optical fiber cable B shown and explained in FIG. 4 is wound around a support wire C having a plastic coating layer 9 made of polyvinyl chloride or the like provided on the outer periphery of a steel wire 8. .

Such an optical fiber cable for outdoor wiring can be easily separated by unwinding it from the support wire C.

FIG. 2 shows a second embodiment of the invention in a cross-sectional view.

In this embodiment, a tear string 6 is attached to one recess 5 of the indoor optical fiber cable B shown and explained in FIG.
An outdoor core wire A is provided with a protective coating layer 7 made of extrusion coating of polyvinyl chloride, polyethylene, etc. on the outer periphery of the cable B, and a plastic coating of polyvinyl chloride or the like on the outer periphery of the steel wire 8. It is constructed by winding it around a support wire C provided with a layer 9.

Such an optical fiber cable for outdoor wiring can be used indoors as shown in FIG. It is obvious that it can be applied as an optical fiber cable for wiring. Note that when applying the protective coating layer 7, if a suitable mold release agent such as talc is applied on the indoor cable B in advance, the indoor cable B can be easily taken out during use. Also,
The tear string 6 may be attached to both recesses 5 in some cases.

In this configuration, deterioration of transmission characteristics due to tension or bending can be solved by winding a steel wire (for example, 1.2 mmφ) around a support wire C with a plastic coating on the outer periphery. In this case, the reinforcing cores 2 ( For example, 0.7 mmφ) mainly works to suppress shrinkage of the plastic coating layer 7 due to temperature changes.

FIG. 3 shows a cross-sectional view of an embodiment of the third invention, which is a cable suitable for outdoor wiring like the second invention.

In this embodiment, indoor cable B shown in FIG.
and supporting steel wire 8 are arranged in parallel, and a tear string 6 is attached to one recess 5 of the indoor cable B.
A protective coating layer 10 formed by extrusion coating polyvinyl chloride, polyethylene, etc. in a darmer shape is provided over the entire structure. It is obvious that such an optical fiber cable can be used as an indoor optical fiber cable as shown in FIG. 4 by tearing and removing the protective coating layer 10 using the tear string 6. Note that the protective coating layer 10
If a suitable mold release agent such as talc is applied on the indoor cable B in advance, it will be easier to take out the indoor cable B during use. Note that the tear string 6 may be attached to both recesses 5 in some cases.

(Effect of the invention) In the optical fiber cable of the present invention, if the shared optical fiber cable does not have a protective coating layer and is wound directly on the support wire, it can be easily separated from the support wire and used as is for indoor use. Optical fiber cables that can be used and shared are provided with a protective coating layer and are wound on support wires.
Since the tear string is inserted under the protective coating layer, it can be easily separated from the support wire, and the protective coating layer can be easily separated by the tear string, so it can be used as is for indoor use, and in any case. Unlike conventional methods, there is no need to connect different types of optical fiber cables indoors and outdoors, reducing construction costs.

In addition, for those equipped with a Daruma-shaped bulk protective coating layer, a tear string is inserted under the protective coating layer, so it is easy to take out the optical fiber cable for indoor use inside the protective coating layer. As with the optical fiber cable of the present invention, there is no need to connect different types of fiber cables indoors and outdoors.

Two recesses are formed on the surface of the plastic coating layer, which has a substantially circular cross section, in areas perpendicular to the plane formed by the optical fiber and the reinforcing cores arranged at intervals on the same plane of the optical fiber. This allows it to have the bendability required for indoor and outdoor wiring, and since a cut groove is formed at the bottom of this recess facing the direction of the optical fiber, the depth of the groove can be made shallow. This makes it easier to form the groove during extrusion molding, and also makes it easier to tear and take out the optical fiber.

[Brief explanation of drawings]

FIGS. 1, 2, and 3 each show a cross-sectional view of an embodiment of a two-core optical fiber cable for outdoor wiring. FIG. 4 shows a cross-sectional view of an optical fiber cable commonly used in the two-core optical fiber cable for outdoor wiring shown in FIGS. 1, 2, and 3. 5 and 6 are cross-sectional views of conventional optical fiber cables for indoor wiring and conventional optical fiber cables for outdoor wiring. DESCRIPTION OF SYMBOLS 1... Optical fiber, 2... Reinforcement core, 3... Plastic coating layer, 4... Cut groove, 5... Recess, 6... Tear string, 7, 10... Protective coating layer, 8... Steel wire, A... Outdoor safety wire, B...Indoor cable, C...Support wire.

Claims (1)

[Scope of Claims] 1. Two optical fibers arranged in parallel or in contact with each other or with a slight interval between them, reinforcing cores arranged at intervals on the same plane on both sides of the optical fibers, and these optical fibers. The optical fiber and the reinforcing core are provided with an extruded plastic coating layer having a substantially circular cross section, and the coating layer has two recesses formed on the surface of the portion perpendicular to the plane formed by the optical fiber and the reinforcing core. , and a cable in which a cut groove facing the optical fiber is formed at the bottom of the recess is wound around a support wire having a plastic coating on the outer periphery of a steel wire. fiber optic cable. 2. Two optical fibers that are arranged in parallel or in contact with each other or with a slight spacing between them, and reinforcing cores that are spaced apart on the same plane on both sides of the optical fibers, and these optical fibers and reinforcing cores. A commonly extruded plastic coating layer having a generally circular cross section is provided, and the coating layer has two recesses formed on the surface of the portion perpendicular to the plane formed by the optical fiber and the reinforcing core, and the bottom of the recesses. A cable with a protective coating layer on the outer periphery of the cable is formed with a cut groove facing in the direction of the optical fiber, and a tear string is attached to one or both of the concave portions of the coating layer. A two-core optical fiber cable, characterized in that it is wound around a support wire provided with a plastic sheath. 3. Two optical fibers that are arranged in parallel or in contact with each other or with a slight spacing between them, and reinforcing cores that are spaced apart on the same plane on both sides of the optical fibers, and these optical fibers and reinforcing cores. A commonly extruded plastic coating layer having a generally circular cross section is provided, and the coating layer has two recesses formed on the surface of the portion perpendicular to the plane formed by the optical fiber and the reinforcing core, and the bottom of the recesses. A cut groove is formed in the direction of the optical fiber, a steel wire is arranged parallel to the cable with a tear string attached to one or both of the recesses of the coating layer, and a daruma covering the cable and the steel wire is formed. A two-core optical fiber cable characterized by having a shaped plastic protective covering.