JP2782124B2 - Fiber optic cable - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical fiber cable and, more particularly, to an optical fiber cable having an external pressure detecting function so as to be able to monitor the condition of the external pressure that causes the cable jacket before the cable jacket is broken. It relates to a fiber cable.

[0002]

2. Description of the Related Art Conventional monitoring of an optical fiber cable includes:
Primarily, 1) gas filling monitoring and 2) insulation monitoring have been used. The gas filling monitoring of 1) is to fill or supply dry air or the like in the cable, and when the cable and the connection point are damaged and the gas flows out, the pressure sensor installed in the connection part detects an abnormality. is there. In the insulation monitoring of 2), a pair of alarm wires (wires with perforated insulation layers) inserted in the outer layer of the cable, and if the cable is damaged by water and the cable is damaged by water, the insulation resistance is reduced. Drop,
This is to detect an abnormality.

[0003]

(1) Among the conventional monitoring methods described above, the gas filling monitoring of (1) requires a gas supply device, a pressure sensor, a power supply line and a signal line of the sensor, and furthermore, a cable terminal. The scum dam must be formed. Therefore, the cost increases. The insulation monitoring of 2) requires the above-mentioned alarm line. (2) Since both types use an electric wire made of a metal conductor, they cannot be applied to the non-metallic type which is a feature of the optical cable. (3) In both types, the abnormality can be sensed only after the cable jacket is destroyed, and it is not possible to detect the minute stress strain which becomes a problem when designing the life of the optical cable.

[0004]

Means for Solving the Problems Mainly as shown in FIG.
A unit having substantially the same structure as that of the conventional spacer type is used. However, in this case, the spacer 10 is not limited to a normal groove (a deep groove 16 whose depth A is larger than the diameter of the optical fiber core 20 to be housed). It has a shallow groove 18 (the depth B of which is smaller than the diameter of the optical fiber core 22 accommodated). An optical fiber cable is configured using the above units.

[0005] As shown in FIG. 4, only the optical fiber core 22 is accommodated in the shallow groove 18 (the optical fiber core 2 for communication).
The external pressure detecting unit 32 (which does not have the deep groove 16 for accommodating the zero) may be inserted along the entire length of the optical fiber cable.

[0006]

[Operation] The depth B of the shallow groove 18 is the optical fiber core 2 for detection.
When the diameter is smaller than the diameter of 2, the detection optical fiber core wire 22 housed in the groove 18 partially emerges above the line 19 connecting both ends of the groove 18 as shown in FIG. Therefore, when a lateral pressure acts on the cable, a load is applied to the optical fiber 22 for detection (not protected by the spacer 10 like the optical fiber 20 for communication in the deep groove 16).

When a lateral pressure acts on the optical fiber for detection 22, the transmission loss increases. This can be detected by a generally used light source and power meter. Further, by connecting to the OTDR, it is possible to detect the position at which the external pressure acts together with the change in the transmission loss.

[0008]

Embodiment 1 [Structure] In FIG. 1, reference numeral 10 denotes a spacer, which is FR at the center.
A body 14 having a tension member 12 made of P or the like and made of plastic (for example, high-density polyethylene).
A plurality of spiral deep grooves 1
6 and shallow grooves 18 are provided. The communication optical fiber 20 is accommodated in the deep groove 16. As shown in FIG. 1B, the depth A of the deep groove 16 is sufficiently larger than the diameter of the optical fiber 20. Therefore, the communication optical fiber 20 is protected from external force as in the case of a normal spacer-type unit.

In the shallow groove 18, a detection optical fiber core wire 22 is provided.
To store. As shown in FIG. 1C, the shallow groove 18 is a shallow groove whose depth B is smaller than the diameter of the optical fiber core 22. In this case, the design is made such that about 1/3 of the detection optical fiber core wire 22 comes out above the line 19 connecting both ends of the shallow groove 18. Numeral 24 denotes a presser winding, which is made of a plastic tape or the like. 26 is a sheath made of, for example, polyethylene. The above materials are all nonmetallic.

[Detection of External Pressure] When an external pressure (side pressure) is applied to an arbitrary position of the cable, a load is first applied to the optical fiber 22 for detection. When a load is applied, the transmission loss of the detection optical fiber core wire 22 increases. The lateral pressure and the loss increase value are almost proportional. Therefore, the optical fiber core 22 for continuous detection by a generally used light source and power meter is used.
Can easily know that external pressure has been applied and the degree thereof. In addition, the position can be known by using the OTDR.

When the external pressure further increases, the spacer 10 is deformed, and finally the external pressure acts on the optical fiber 20 for communication. Can foresee.

[0012]

Embodiment 2 FIG. 2 shows an example in which the above cable is used for a submarine cable. From the cable of FIG.
Excluding 6 (or covered with a thin sheath)
Is used as a spacer type unit 30, and a water impermeable layer 40, an insulator wire 42, a presser winding 44, and a jacket 46 are sequentially provided thereon. With such a structure, it is possible to detect when the cable is anchored on the seabed and its detection. In addition, it can also be used as an optical unit of a combined power / optical submarine cable.

[0013]

Third Embodiment FIG. 3 shows an example in which the present invention is applied to a cable having a large number of cores. In place of the sheath 26 of the cable shown in FIG.
Then, they are gathered around the center tension member 50, and the presser winding 52 and the sheath 54 are applied.

[0014]

Embodiment 4 As shown in FIG. 4 (b), one of the cables shown in FIG.
Excluding the deep groove 16 and the optical fiber 20 for communication from the three spacer type units 30,
And Also, as shown in FIG. 4C, a dedicated communication unit 34 is obtained by removing the shallow groove 18 and the detection optical fiber core 22 from one spacer type unit 30 of the cable of FIG. Then, as shown in FIG. 1A, the external pressure detecting unit 32 and the communication unit 34 are twisted and assembled to form a cable.

[0015]

As described above, since the groove of the spacer has a depth smaller than the diameter of the optical fiber core housed therein, the optical fiber functions as a sensor for detecting the external pressure as described above. The following effects are obtained. (1) It is possible to linearly detect a state in which the cable is deformed by receiving a certain external pressure, and to detect an abnormality from a low level state. (2) Although the cable jacket is not destroyed, it is possible to detect a small external pressure that causes serious distortion in the optical fiber inside the cable. (3) Since a sensor having no structure using any metal can be used, there is no need to worry about induction. (4) By using the OTDR, sensors can be provided at all locations in the longitudinal direction. (5) Since light is used for the sensor signal, a long monitoring of about 100 km is possible if a low-loss optical fiber is used.

[Brief description of the drawings]

1A is an explanatory view of a first embodiment of the present invention, FIG. 1B is an enlarged explanatory view of a deep groove portion, and FIG. 1C is an enlarged explanatory view of a shallow groove portion.

FIG. 2 is an explanatory diagram of a second embodiment of the present invention.

FIG. 3 is an explanatory diagram of a third embodiment of the present invention.

FIG. 4 is an explanatory view of Embodiment 4 of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Spacer 12 Tension member 14 Main body 16 Deep groove 18 Shallow groove 19 Line 20 Optical fiber core wire for communication 22 Optical fiber core wire for detection 24, 52 Holding coil 26, 54 Sheath 30 Spacer type unit 32 External pressure detection dedicated unit 34 Communication dedicated unit 40 impermeable layer 42 insulator wire 44 presser winding 46 jacket

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Asawa Tanaka 1-5-1, Kiba, Koto-ku, Tokyo Inside Fujikura Electric Wire Co., Ltd. (72) Inventor Hiroshi Yamanouchi 1-5-1, Kiba 1-chome, Koto-ku, Tokyo Fujikura Inside the Electric Wire Co., Ltd. (72) Inventor Hideo Suzuki 1440, Murosaki, Sakura-shi, Chiba Prefecture Inside the Sakura Plant of Fujikura Electric Wire Co., Ltd. (56) References JP-A-58-117509 (JP, A) , U) Japanese Utility Model Showa 60-67610 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) G02B 6/44 366

Claims (2)

(57) [Claims] 1. A spacer having a spiral groove on a side surface of a plastic elongated cylindrical body, wherein an optical fiber core is accommodated in the groove, and a presser winding is provided thereon, and the groove is provided. Is an optical fiber cable in which a unit dedicated to detecting external pressure whose depth is smaller than the diameter of the optical fiber is inserted over the entire length. Wherein the spacer having a spiral groove of plural on the side surface of a plastic elongated cylindrical body, said optical <br/> Fiber cores are housed in each groove, the winding holding thereon is subjected An optical fiber cable having a spacer-type unit comprising a groove whose depth is smaller than a diameter of an optical fiber core to be stored and a groove whose diameter is larger than that of the optical fiber cable.