JP4252969B2 - Fiber optic cable - Google Patents

Description

  The present invention relates to an optical fiber cable mainly intended to prevent insect damage such as cicada.

Currently, an indoor fiber cable shown in FIG. 1 or an optical fiber cable called a drop cable 20 shown in FIG. 2 is used as an optical fiber cable used for drawing from a trunk line to a house.
The indoor cable 10 is formed as an optical fiber cable by providing strength members 2 and 2 on both sides of the optical fiber 1 and covering the optical fiber and the strength member together with a sheath 3 having a substantially rectangular cross section. The drop cable 20 further includes a support wire 5 that is connected to the indoor cable by being collectively covered with the sheath 3 via the neck portion 4. As the optical fiber 1, one or a plurality of optical fiber core wires or a tape-shaped optical fiber core wire is used. These cables are usually provided with notches 6 along the length of the optical fiber cable so that the internal optical fiber 1 can be taken out without using a special tool when laying. The optical fiber 1 disposed under the notch 6 can be taken out by manually tearing along the notch 6 in the longitudinal direction.

However, in the optical fiber cable having such a notch 6, there is a problem that the kuma-zemi punctures the egg-laying tube in order to lay eggs in the notch 6 and breaks or damages the optical fiber 1 inside. This is evident from the detailed investigation of the scratches on the broken fiber optic cable, confirming the damage corresponding to the angle of the laying tube, past cases, and being limited to the area where the burrowing was occurring. It is believed that. In addition, only the komazemi has been confirmed at present, but since the cable covering thickness of the notch 6 is thinner than other parts, such damage may be caused by other types of insects and birds. It is done.
On the other hand, the rapid progress of FTTH (Fiber, To, The, Home) is expected in the future, and it is expected that the demand for indoor cables and drop cables for pulling into ordinary houses will increase. Therefore, there is an urgent need to prevent such damage. However, to promote FTTH, it is necessary to prevent cicada harm at the lowest possible cost.

Patent Document 1 discloses an optical fiber cable in which a notch shape is devised as an attempt to prevent such insect damage. Further, an optical fiber cable without a notch such as a drop cable 30 shown in FIG. 3 can be considered.
JP 2002-90594 A

However, as a result of earnest investigation of what was actually laid in the field, it was found that even in the above-described unnotched drop cable 30, the disconnection probability due to cicada spawning occurred although the optical fiber disconnection probability decreased. Further, when the optical fiber core is a tape core, it is considered that the probability of disconnection due to the semi-vibrated oviduct is further increased. This means that the cicada is laying eggs at places other than the notches, and it means that even with the optical fiber cable of Patent Document 1, damage cannot be prevented.
Further, the drop cable 30 has a certain limit in handling properties, such as a specially devised tool is required to take out the optical fiber core wire inside the sheath 3. Therefore, an object of the present invention is to provide an optical fiber cable that effectively prevents insect damage and further has good handling properties.

In order to solve the above-described problem, an optical fiber cable according to claim 1 is provided with a tensile body disposed on both sides of one or more optical fibers, and the optical fiber and the tensile body are collectively covered with a sheath having a substantially rectangular cross section. inner optical fiber cables and without, the outer periphery of one of the inner optical fiber cable covered with an outer layer resin coating, an optical fiber cable provided with a notch in the longitudinal direction of the outer resin coating the outer periphery, said from said outer resin coating surface The distance to the optical fiber is 2 mm or more .

An optical fiber cable according to a second aspect is the optical fiber cable according to the first aspect, wherein the notches are two or more places outside the one tensile strength body in the arrangement direction of the optical fiber and the tensile strength body. It is characterized in that it is provided at the location.

An optical fiber cable according to a third aspect is the optical fiber cable according to the first or second aspect , wherein talc is applied to a surface of the sheath.

An optical fiber cable according to claim 4 is the optical fiber cable according to any one of claims 1 to 3 , wherein the inner optical fiber cable is further supported by being collectively covered and connected by a sheath via a neck portion. characterized in that it comprises a line.

An optical fiber cable according to a fifth aspect is the optical fiber cable according to the fourth aspect, wherein the notch is at two or more locations outside the support line in the arrangement direction of the optical fiber and the support line. It is characterized by being provided in .

  The optical fiber cable according to claim 1 is capable of preventing, for example, a laying tube of a bearfish from reaching the optical fiber by the outer layer resin coating, and removing the outer layer resin coating by providing a notch in the outer layer resin coating. The internal optical fiber cable can be easily taken out. Since the outer layer resin coating can prevent insect damage, there is no need to consider insect damage in the shape of the internal optical fiber cable, and a notch is provided in the sheath of the internal optical fiber cable in consideration of good handling characteristics when taking out the optical fiber. In consideration of compatibility with existing equipment (for example, a casing used at a connection point), it can be matched with the dimensions of a conventional indoor cable. Therefore, it is possible to achieve both insect prevention, handling, and consistency with existing equipment. When considering compatibility with existing equipment, the dimensions of the indoor cable should be 1 mm to 2.5 mm on the short side and 3 mm to 4 mm on the long side as in the conventional general dimensions. preferable. As the optical fiber, for example, one or a plurality of optical fiber cores having an outer diameter of 0.25 mm or optical fiber tape cores are generally applied.

  In the optical fiber cable according to claim 1, there is a high possibility that the notch provided on the outer periphery of the outer layer resin-coated outer periphery is inserted with the coagulation tube. However, as in the optical fiber cable according to claim 2, the notch If it is provided at two or more locations outside the tensile strength body, the distance from the notch to the optical fiber can be secured, and the tensile strength body can prevent the laying tube from reaching the optical fiber. Even if the optical fiber is inserted, disconnection and damage of the optical fiber can be effectively prevented. Also, when tearing the outer resin coating, the tearing force is applied to the vicinity of the notch, but the distance from the notch to the optical fiber can be secured, and the strength member prevents the tearing force from reaching the optical fiber. Therefore, it is possible to effectively prevent an accident when tearing. Furthermore, by providing two notches on the outer side of the strength member, that is, at an eccentric position, the outer resin coating is divided into two regions, a wide region and a narrow region, by the notch. When tearing, first, the outer resin coating is cut in the longitudinal direction by removing a narrow area that is easy to remove, and then the outer resin coating is efficiently removed by peeling off the wider area. be able to.

By the way, as a result of laying the drop cable 30 without a notch and investigating the damage of the cicada's egg-laying tube, it was found that there is no egg-laying tube penetrating the drop cable 30. The outer shape of the portion excluding the support wire of the drop cable 30 is a rectangle having a short side of about 2 mm and a long side of about 3 to 4 mm, and does not penetrate a thickness of about 2 mm. From the investigation results, it was found that it is effective to set the distance from the outer layer resin-coated surface to the optical fiber to be 2 mm or more as in the case of the optical fiber cable according to claim 1 in order to prevent harm.

The optical fiber cable according to claims 1 and 2 can be used in a state where the outer resin coating is partially removed and the internal optical fiber cable is exposed. That is, the outer layer resin coating and the sheath of the inner optical fiber cable may be required to have the same characteristics. In this case, for example, it is effective to use the same kind of resin. Generally, low-density polyethylene and flame-retardant polyolefin are used for the sheath of the indoor cable. However, when these resins are used for the sheath of the inner optical fiber cable and the outer layer resin coating, the outer layer resin is formed on the outer periphery of the sheath. There is a tendency for the two to be in close contact when the coating is applied. In the case of the close contact, it becomes difficult to remove the outer layer resin coating and take out the inner optical fiber cable. As a countermeasure, there is a method of placing a presser roll such as polyester nonwoven fabric or polyester terephthalate tape between the inner optical fiber cable and the outer layer resin coating so that the outer layer resin coating and the inner optical fiber cable are not in close contact. Since it is also necessary to remove these at the time of taking out, the laying workability becomes poor. As a result of intensive studies, the inventor effectively applied the talc to the sheath surface of the inner optical fiber cable as in the case of the optical fiber cable according to claim 3 to effectively adhere the outer layer coating resin and the sheath of the inner optical fiber cable. Found to prevent. According to such an optical fiber cable, since no new member such as the above-described presser winding is provided, no new removal work is required, and the internal optical fiber cable can be easily taken out.

As in the case of the optical fiber cable according to the fourth aspect , since the internal optical fiber cable is provided with the support wire connected through the neck portion, it can be well aligned with the conventional drop cable.

Further, when the internal optical fiber cable has a support line connected through the neck, as in the optical fiber cable according to claim 5 , by providing the notch outside the support line, the distance between the notch and the optical fiber can be reduced. Since a support wire that can be secured for a longer time and generally has a size larger than that of the strength member prevents the laying tube and tearing force from reaching the optical fiber, further effects of disconnection and damage of the optical fiber can be expected. In addition, the notch is located outside the support line, that is, at an eccentric position.
By providing the location, the outer layer resin coating is divided into two regions, a wide region and a narrow region, by the notch. When tearing, first, the outer resin coating is cut in the longitudinal direction by removing a narrow area that is easy to remove, and then the outer resin coating is efficiently removed by peeling off the wider area. be able to.

Embodiments of the present invention will be described below in more detail with reference to the drawings.
The optical fiber cable 41 in FIG. 4 uses a conventional indoor cable equivalent as the internal optical fiber cable 40. As the optical fiber 1, four optical fiber cores having an outer diameter of 0.25 mm and two optical fiber tape cores 11 and 11 collectively covered with a tape resin are laminated and arranged, and tensile strength members 2 and 2 are provided on both sides thereof. The outer layer resin coating 7 made of a thermoplastic resin was applied to the outside of the sheath 3 which was disposed and covered with a sheath 3 made of a thermoplastic resin. The outer dimension of the outer resin coating 7 is about 6 mm × about 9 mm, and the outer dimension of the internal optical fiber cable is about 2 mm × about 3 mm. The inner optical fiber cable is provided with a notch 6, and the outer layer resin coating is also outside of one of the strength members 2 (from the straight line A in the diagram) when viewed from the direction in which the optical fiber 1 and the strength member 2 are arranged (left and right in the figure). Notches 8 and 8 are provided at two locations on the left area. In the present embodiment, the projection distance from the strength member 2 to the notch 8 is 1 mm, and the projection distance between the notches 8 and 8 is 2.5 mm. The material of the strength members 2 and 2 is not particularly limited as long as it has the necessary strength properties. However, from the size of the indoor cable and the necessary tension properties, steel wire, aramid FRP, and glass FRP of about φ0.5 mm are used. Is commonly used.

  With this configuration, when the outer resin coating 7 is cut along the notches 8 and 8 and the inner optical fiber cable 40 is taken out, the two notches 8 and 8 of the outer resin coating 7 are used as shown in FIG. The sandwiched region 9 can be easily peeled off with a nipper or the like. For this reason, the internal optical fiber cable 40 can be easily taken out. Further, since the positions of the notches 8 and 8 are arranged outside the one strength member 2 of the internal optical fiber cable 40, when the internal optical fiber cable 40 is taken out in the middle of the length of the optical fiber cable 41, a nipper or the like is used. Since the optical fiber 1 is disposed closer to the center of the cross section than the notches 8 and 8 when the outer resin coating 7 is cut, the risk of damaging the internal optical fiber with a nipper or the like is reduced.

As another embodiment, as shown in FIG. 6, an internal optical fiber cable 60 that uses a drop cable having a support wire can be applied. In this embodiment, since the notches 8 and 8 are provided outside the support line, it is possible to suppress damage to the internal cable when notching with a nipper or the like. In addition, the minimum distance (a) between the outer resin-coated outer surface and the optical fiber is set to 2 mm or more, which is effective in suppressing the damage caused by the blackberry to lay eggs.
Further, as shown in FIG. 7, the outer periphery of the inner optical fiber cable 40 is covered with an outer resin coating 7 provided with predetermined notches 8 and 8, and a support wire 5 is added to the outer side of the outer resin coating 7. Also good. Further, as shown in FIG. 8, when two notches 8 and 8 are provided on one side in the long side direction of the cross section of the outer layer resin coating and notches 12 are provided on the other side, they are sandwiched between the notches 8 and 8. After the region 9 is removed, the remaining outer layer resin coating 7 can be divided into two parts from the notch 12, so that the removal operation is easy. The notch 12 can be applied to any of the embodiments described above.
Furthermore, when talc is applied to the surface of the sheath 3 of the inner optical fiber cables 40 and 60 of the optical fiber cables 41 and 61, the outer layer resin coating 7 and the sheath 3 can be prevented from sticking, and the outer layer resin coating 7 is removed. The operation of taking out the internal optical fiber cables 40 and 60 is facilitated. Therefore, when the optical fiber cables 41 and 61 are used for drawing an optical fiber into a general house, for example, when flame resistance is required, the same kind of flame retardant resin is used for the outer layer resin coating 7 and the sheath 3. However, the workability of taking out the internal optical fiber cables 40, 60 is not hindered and is more preferable.

Cross section of a typical indoor cable Cross section of a typical drop cable Cross section of drop cable without notch Sectional drawing showing embodiment of the optical fiber cable concerning this invention Schematic diagram showing a state in which the outer resin coating of the optical fiber cable according to the present invention is removed Schematic diagram showing a state in which the outer resin coating of the optical fiber cable according to the present invention is removed Schematic diagram showing a state in which the outer resin coating of the optical fiber cable according to the present invention is removed Schematic diagram showing a state in which the outer resin coating of the optical fiber cable according to the present invention is removed

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical fiber 2 Strength body 3 Sheath 4 Neck part 5 Support wire 6 Notch 7 Outer layer resin coating 8 Notch 9 Area | region pinched by the notch 10 Indoor cable 11 Optical fiber tape core wire 12 Notch 20 Drop cable 30 Drop cable 40 Internal optical fiber cable 41 Optical fiber cable 60 Internal optical fiber cable 61 Optical fiber cable

Claims (5)

A tensile body is arranged on both sides of one or more optical fibers, and the optical fiber and the tensile body are collectively covered with a sheath having a substantially rectangular cross section to form an internal optical fiber cable, and the outer periphery of one internal optical fiber cable is formed. An optical fiber cable covered with an outer resin coating and provided with a notch in the longitudinal direction of the outer periphery of the outer resin coating , wherein the distance from the outer resin coating surface to the optical fiber is 2 mm or more cable.   2. The optical fiber cable according to claim 1, wherein the notch is provided at two or more locations outside the one strength member in the arrangement direction of the optical fiber and the strength member. Fiber optic cable. 3. The optical fiber cable according to claim 1, wherein talc is applied to a surface of the sheath. The optical fiber cable according to any one of claims 1 to 3 , wherein the internal optical fiber cable further includes a support wire that is connected by being collectively covered with a sheath via a neck portion. cable. 5. The optical fiber cable according to claim 4 , wherein the notch is provided at two or more locations outside the support line in the direction in which the optical fiber and the support line are arranged. Fiber cable.

Images