JP4615392B2 - Fiber optic cable - Google Patents

Description

The present invention relates to an optical fiber cable. In particular, the present invention relates to a small-core wiring cable used in the vicinity of an optical fiber subscriber's home, a drop cable used for lead-in wiring of an optical fiber into a home, or an indoor cable used for routing wiring in a home or campus.

At present, optical fiber cables shown in FIGS. 11 and 12 are used as optical fiber cables used for drawing from the main line into the house or used in the house or on the premises.
An optical fiber cable 100 shown in FIG. 11 includes a tension member 102 on both sides of an optical fiber unit 101, and the optical fiber unit 101 and the tension member 102 are collectively covered with a substantially flat sheath 103. ing. An optical fiber cable 110 shown in FIG. 12 further includes a support wire 105 that is covered and connected by a sheath 103 via a neck 104. As the optical fiber unit 101, one or a plurality of optical fibers or optical fiber tapes are used.

In general, these optical fiber cables 100 and 110 are formed with V-shaped notches 106 along the longitudinal direction, and the optical fiber cable sheath 103 is torn by using the notch 106 at the time of laying or the like. For convenience, the optical fiber unit 101 is taken out. The notch 106 is generally disposed as close to the optical fiber unit 101 as possible in order to minimize the distance of the crack necessary for tearing the sheath 103 and reduce the tear resistance.

As the sheath 103, polyvinyl chloride, polyethylene or the like is generally used. Such an optical fiber cable is disclosed in Patent Document 1, for example. In the device disclosed in Patent Literature 1, in consideration of the take-out property of the optical fiber unit, two or more pairs of notches are provided in the sheath, and a device for dividing the optical fiber cable into three is devised.

In recent years, optical fiber tapes have been actively adopted in consideration of the high density of cables and the convenience of multi-core batch connection. Furthermore, the thing which improved the single fiber branching property of the optical fiber tape itself is also developed. Also, as an optical fiber cable excellent in workability, an optical fiber unit adopting, for example, a large-diameter optical fiber single-core wire having an outer diameter of 0.5 mm instead of a conventional optical fiber single-core wire having an outer diameter of 0.25 mm. Has been developed. Such optical fiber cables are disclosed in Non-Patent Documents 1 and 2, for example.
JP 2004-117854 A Proceedings of the 2005 IEICE General Conference B-10-20 Proceedings of the 2005 IEICE General Conference B-10-10

Although the optical fiber tape of Patent Document 1 also contributes to the improvement of the take-out property, since the optical fiber cable is divided into three, the tearing process is required twice. In particular, in the second tearing, it is necessary to grip the sheath directly above the optical fiber unit, which may cause damage to the optical fiber unit, and further improvement in takeout is required. This is especially true when using the above-described optical fiber tape with improved single-fiber branching or a large-diameter optical fiber single-core wire having an outer diameter of 0.5 mm.

That is, an optical fiber tape with improved single-core branching property has a thin outer sheath and tends to become weak, and there is a strong concern that damage will occur if an excessive force is applied to separate the sheath and the optical fiber tape. Further, for example, when a large-diameter optical fiber single-core wire having an outer diameter of 0.5 mm is used, the object to be extracted becomes large, so that the extraction tends to be difficult. The optical fiber cable may be exposed to various temperature environments such as −30 ° C. to + 40 ° C., and it is necessary to ensure good take-out property in any temperature environment.

Accordingly, an object of the present invention is to provide an optical fiber cable in which the take-out property of the optical fiber tape is further improved in various temperature environments.

An optical fiber cable according to claim 1 is an optical fiber unit in which a plurality of optical fibers are arranged in a substantially flat shape, and tension members arranged on both sides of the optical fiber unit on a center line extension in the long side direction of the optical fiber unit. A V-shaped notch that covers the optical fiber unit and the tension member in a lump and is arranged on each of both surfaces of the substantially flat sheath along the long side of the optical fiber unit and the long side of the sheath. The optical fiber unit is composed of a plurality of single-core optical fibers arranged in a row adjacent to each other, and the single-core optical fiber is UV-cured to an outer diameter of φ250 μm on a bare optical fiber of φ125 μm A single core with an outer diameter of 0.5 mm coated with resin and further coated with UV curable resin to improve the handling of the optical fiber core If the bottom of the notch is a point A and the point closest to the point A of the optical fiber unit is a point B, the angle γ formed by the center line in the long side direction of the optical fiber unit and the line segment AB is An optical fiber cable having an angle of 30 degrees to 80 degrees.

The optical fiber cable according to claim 2 is the optical fiber cable according to claim 1, wherein the point B has an angle δ from an adjacent interface of a single-core optical fiber located at one end of the optical fiber unit. an optical fiber cable, which is a point of 100 degrees or more 150 degrees or less.

An optical fiber cable according to the present invention includes an optical fiber unit in which a plurality of optical fibers are arranged in a substantially flat shape, tension members arranged on both sides of the optical fiber unit on a center line extension in the long side direction of the optical fiber unit, The optical fiber unit and the tension member are collectively covered, and includes a substantially flat sheath along the long side of the optical fiber unit and a notch disposed on the long side surface of the sheath, The optical fiber is arranged in a substantially flat shape, and is composed of an optical fiber tape that is collectively covered with an ultraviolet effect resin. The ultraviolet curable resin is 3 μm to 25 μm at the thinnest point, the bottom of the notch is point A, the light When the point closest to the point A of the fiber unit is the point B, the long-side direction center line and the line of the optical fiber unit The optical fiber cable is characterized in that the angle γ formed by the minute AB is not less than 30 degrees and not more than 80 degrees.

The optical fiber cable according to the present invention is an optical fiber cable characterized in that the point B is a portion on the short side of the optical fiber tape located at one end of the optical fiber unit.

When optical fiber tapes or optical fiber single core wires are juxtaposed, the optical fiber unit is substantially flat as a whole, and a long side direction and a short side direction are formed at the interface between the sheath and the optical fiber unit. Therefore, according to the optical fiber cable of the present invention , the crack when the sheath is cut is directed to the end side in the longitudinal direction of the optical fiber unit at an angle α of 80 degrees or less with respect to the long-side direction center line of the optical fiber unit. . That is, the crack and the interface in the long side direction between the sheath and the optical fiber unit continue smoothly, and the takeout property of the optical fiber unit can be secured. Further, since the crack progresses while avoiding the tension member arranged on the extension of the center line in the long side direction, the take-out property is not hindered by the tension member. It should be noted that it is practically impossible to manage the crack so as to be surely in a predetermined direction because the progress direction and the arrival point of the crack vary depending on how the tearing force is applied. Therefore, the crack direction is statistically specified by forming a majority in a predetermined direction. Further, the angle α is more preferably 45 degrees or less, and particularly preferably 30 degrees or less.

According to the optical fiber cable of the present invention , even if the optical fiber unit is constituted by a plurality of single-core optical fibers arranged in a row adjacent to each other, the crack and the sheath-optical fiber unit The interface in the long side direction is smoothly continuous, and the takeout property of the optical fiber unit can be secured. Further, in this case, the single-core optical fiber disposed in the center of the optical fiber unit has two adjacent interfaces separated by 180 degrees, and the interface between the sheath and the single-fiber optical fiber is divided into two by the adjacent interface. . However, in the single-core optical fiber arranged at the end of the optical fiber unit, there is one adjacent interface, and the interface between the sheath and the single-core optical fiber is almost 360 degrees. When separating a single-core optical fiber from a sheath, it is preferable that there are few interfaces with the sheath after tearing, but usually there is only one crack, and if one interface is reduced, the other interface is more. Become.

Therefore, from such a viewpoint, it is ideal that the cracks evenly divide the interface (the angle β is 180 degrees). In practice, the angle β is preferably 100 degrees or more and 180 degrees or less. Further, the angle β is preferably 135 degrees or more and 180 degrees or less, and particularly preferably 150 degrees or more and 180 degrees or less. When the center of the notch is arranged immediately above the optical fiber tape unit, the crack runs the shortest distance, so the true desired end of the optical fiber ribbon (ideally, the angle β is 180 degrees). The position of () is not reached, and it reaches inside.

According to the optical fiber cable of the present invention , even when the optical fiber unit is formed of an optical fiber tape, the crack and the interface in the long side direction between the sheath and the optical fiber unit continue smoothly, The take-out property of the fiber unit can be ensured.

By the way, when the optical fiber unit is separated from the torn sheath, a force (separation force) is applied to the optical fiber unit. If this separation force is excessive, the optical fiber unit can be broken. When the separation from the sheath occurs simultaneously with the operation of tearing the sheath, the separation force acts in the opposite direction from the crack arrival point, and a part of the larger force necessary for the tearing operation acts. When the optical fiber unit is composed of an optical fiber tape, if the arrival point of the above-mentioned crack is on the long side of the optical fiber tape, unintentional separation of the optical fiber tapes due to the separating force acting in the opposite direction, that is, Destruction can occur.

Therefore, as in the case of the optical fiber cable having the above configuration, when the reaching point of the crack is mainly a short side of the optical fiber tape located at one end of the optical fiber unit, the separation acting in the opposite direction described above. The force does not contribute to the separation between the centers, and the destruction of the optical fiber tape can be suppressed. Further, since the crack is caused to run from the outside of the optical fiber unit at an angle α, it is also useful for controlling the arrival point of the crack to a location on the short side of the optical fiber tape located at one end of the optical fiber unit.

Further, when the positional relationship between the notch and the optical fiber unit composed of a plurality of single-core optical fibers arranged in a row adjacent to each other as in the optical fiber unit according to claim 1 is set, the crack is mainly A. It runs from point to point B, and the crack and the interface in the long side direction between the sheath and the optical fiber unit continue smoothly, and the takeout property of the optical fiber unit can be ensured. In particular, the optical fiber unit is coated with an ultraviolet curable resin having a diameter of 250 μm on a quartz optical fiber bare wire with a diameter of 125 μm, and further coated with an ultraviolet curable resin to improve the handling of the optical fiber core. In the case of a single-fiber optical fiber having a nominal outer diameter of 0.5 mm, the take-out property tends to be reduced by the larger diameter as compared with a normal outer diameter 0.25 mm fiber. According to the optical fiber cable according to No. 17, it is possible to enjoy the workability of the large-diameter optical fiber while ensuring good takeout of the optical fiber unit.

Further, according to the optical fiber cable according to claim 2, since the point B was point angle δ is less than 180 degrees or more 100 degrees from adjacent the interface of the single-core optical fiber located at one end of the optical fiber unit The probability that the crack will reach within the range of the angle δ is high, and the crack equally divides the sheath-single-core optical fiber interface to improve the take-out property. The angle δ is preferably 135 degrees or more and 180 degrees or less, and particularly preferably 150 degrees or more and 180 degrees or less.

Further, as in the case of the optical fiber cable according to claim 3, when the optical fiber is arranged in a substantially flat shape and the positional relationship between the optical fiber unit and the notch formed of the optical fiber tape collectively covered with the ultraviolet effect resin is set, The crack mainly runs from the point A to the point B, and the interface between the crack and the long side direction between the sheath and the optical fiber unit smoothly continues, and the takeout property of the optical fiber unit can be ensured.
In particular, the optical fiber tape has a structure in which the thinnest portion of the ultraviolet curable resin is 3 μm to 25 μm and has a structure capable of branching later by using an appropriate tool such as a paper file. In the case where it is configured, it tends to be damaged when an excessive force is applied as compared with a normal optical fiber tape. It is possible to enjoy the workability of the optical fiber tape with improved single-core branchability while ensuring the take-out property.

Continuous long-side direction of the interface between the optical fiber unit is smoothly - according to the optical fiber cable according to claim 4 8, even when the optical fiber unit is constituted by an optical fiber ribbon, and cracks, the sheath In addition, it is possible to ensure the take-out property of the optical fiber unit. In addition, since the point B is a place on the short side of the optical fiber tape located at one end of the optical fiber unit, there is a high probability that the crack will reach the short side of the optical fiber tape, Separation, that is, destruction can be suppressed.

An embodiment of an optical fiber cable of the present invention will be described below with reference to the drawings.
The optical fiber cable of the present invention is an optical fiber cable characterized in that a crack generated when the sheath of the optical fiber cable is torn reaches a predetermined position of the optical fiber unit without passing through the tension member.

A first embodiment of the optical fiber cable of the present invention is shown in FIG. In the optical fiber unit 1, a plurality of optical fiber tapes 2 or optical fiber single core wires 4 are arranged so as to be substantially flat as a whole, and the interface between the sheath 5 and the optical fiber unit 1 is in the long side direction. It has a short side direction. FIG. 3A shows a form in which the optical fiber unit 1 is composed of a plurality of optical fiber tapes 2, and FIG. 3B shows that the optical fiber unit 1 is composed of a plurality of single-core optical fibers 4. It is a form.

On the extension of the center line 7 in the long side direction of the optical fiber unit 1, tension members 3 are arranged on both sides of the optical fiber unit 1 as a center. The optical fiber unit 1 and the tension member 3 are collectively covered with a sheath 5 formed in a substantially flat shape in the long side direction (the direction of the center line 7) of the optical fiber unit 1.

In the optical fiber cable according to the first embodiment of the present invention configured as described above, the crack 6 generated when the sheath 5 is torn does not pass through the tension member 3, and the optical fiber unit 1 has a predetermined angle. It is configured to reach a predetermined position. That is, the crack 6 is formed to reach the end 8 of the optical fiber unit at an angle α of 80 degrees or less with respect to the long-side direction center line 7 of the optical fiber unit 1. The angle α is more preferably 45 degrees or less, and particularly preferably 30 degrees or less.

In this way, the optical fiber unit 1 can be easily taken out by allowing the crack 6 to continue smoothly in the long side direction of the interface between the optical fiber unit 1 and the sheath 5. In addition, since the crack progresses while avoiding the tension member 3 arranged on the extension of the long-side direction center line 7, the ease of taking out the optical fiber unit 1 is not hindered by the tension member 3.

As a method for controlling the angle α so that the crack 6 smoothly continues at the interface between the optical fiber unit 1 and the sheath 5, for example, the following method can be cited.
(1) A notch is placed at an appropriate position on the surface of the sheath 5 as the starting point of the crack 6.
(2) A discontinuous point or a discontinuous surface on the material is provided on the sheath 5 at a preferred crack position.
(3) Place bubbles at the preferred crack locations.

By any one of the methods (1) to (3), the crack 6 can be easily reached at a desired position at a desired angle. However, since the traveling direction and the arrival point of the crack 6 vary depending on how to apply the tearing force, it is practically difficult to manage the crack 6 so as to surely reach the end portion 8. In the optical fiber cable of the present invention, the crack 6 reaches a predetermined traveling direction and a reaching point with a statistically high probability.

A second embodiment of the optical fiber cable of the present invention will be described with reference to FIG. In this embodiment, the optical fiber unit 1 is composed of a plurality of single-core optical fibers 4 arranged in a row adjacent to each other.

In this embodiment, the arrival point of the crack 6 is a predetermined position of the single-core optical fiber 4 a located at one end of the plurality of single-core optical fibers 4 forming the optical fiber unit 1. Here, the predetermined position is a position 12 where the angle β from the adjacent interface 11 between the single-core optical fiber 4a and the adjacent single-core optical fiber 4b is 100 degrees or more and less than 180 degrees.

Also in the optical fiber cable of the present embodiment, the crack 6 reaches smoothly in the long side direction of the interface between the optical fiber unit 1 and the sheath 5 by appropriately setting the angle α as in the first embodiment. Thus, the optical fiber unit 1 can be easily taken out.

In the optical fiber cable of this embodiment, the single-core optical fiber 4 arranged at both ends of the optical fiber unit 1 has two adjacent interfaces with adjacent single-core optical fibers 4, and these two adjacent The interfaces are 180 degrees apart. As a result, the interface between the sheath 5 and the single-core optical fiber 4 is vertically divided into two by the two adjacent interfaces.

On the other hand, the single optical fiber 4a disposed at both ends of the optical fiber unit 1 has only one adjacent interface because there is only one adjacent single optical fiber 4, and the single optical fiber 4a The interface with the sheath 5 is formed over approximately 360 degrees. In order to facilitate removal of the single-core optical fiber 4 a from the sheath 5, it is preferable that the interface between the single-core optical fiber 4 a and the sheath 5 after tearing the sheath 5 by the crack 6 is small. When the sheath 5 is cut by one crack 6, if one interface is reduced, the other interface is increased.

Therefore, it is most preferable to form the crack 6 so that the interface between the single-core optical fiber 4a and the sheath 5 is evenly divided (the angle β is 180 degrees). In practice, the angle β is 100 degrees. It is preferable to form the crack 6 so as to be 180 degrees or less. Furthermore, the angle β is preferably 135 degrees or more and 180 degrees or less, and particularly preferably 150 degrees or more and 180 degrees or less.

The single-core optical fiber 4 constituting the optical fiber unit 1 may be set to a nominal outer diameter of 0.5 mm or more in consideration of other workability during installation. In this case, compared with a normal fiber having an outer diameter of 0.25 mm, the outer diameter of the single-core optical fiber 4 is increased, so that the conventional take-out performance is lowered. Since the crack 6 can be formed at a preferred position, the ease of work by using the large-diameter optical fiber can be enjoyed while ensuring the ease of taking out the optical fiber unit 1.

A third embodiment of the optical fiber cable of the present invention will be described with reference to FIG. In this embodiment, the optical fiber unit 1 is composed of one or more optical fiber tapes 2. Each of the optical fiber units 1 shown in FIGS. 5A to 5C is configured by one optical fiber tape 2 and two lights arranged in the direction of the long-side direction center line 7 of the optical fiber unit 1. The form comprised with the fiber tape 2 and the form comprised with the two-layer optical fiber tape 2 in the direction orthogonal to the long-side direction centerline 7 of the optical fiber unit 1 are shown.

When the optical fiber unit 1 is taken out from the sheath 5 by tearing the sheath 5 with the crack 6, a force to separate the optical fiber unit 1 from the sheath 5, that is, a separating force acts. If this separation force is excessive, the optical fiber unit 1 may be destroyed. When the operation of separating the optical fiber unit 1 from the sheath 5 at the same time as the operation of tearing the sheath 5 with the crack 6, the force necessary for the tearing operation (the tearing force) is larger than the separating force, and therefore the crack 6 Reaches the position of the interface with the optical fiber unit 1, and at the same time, a part of the large tearing force is applied to the optical fiber unit 1.

In the form in which the optical fiber unit 1 is composed of the optical fiber tape 2, when the position where the crack 6 reaches the interface with the optical fiber unit 1 is the long side of the optical fiber tape, the optical fiber unit Unintentional separation of the optical fiber tape 2, that is, breakage can occur due to the separation force or the tearing force acting on 1.

On the other hand, when the position where the crack 6 reaches is on the short side of the optical fiber tape 2 constituting the optical fiber unit 1, the separation force or the tearing force acting on the optical fiber unit 1 is the center. The optical fiber tape 2 can be prevented from being broken without contributing to the separation.

Therefore, in the optical fiber cable of this embodiment, the crack 6 reaches the short side of the optical fiber tape 2 disposed at one end of the optical fiber unit 1. In addition, since the crack 6 is formed with an angle α from the surface of the sheath 5, the crack 6 can smoothly reach the long side of the interface between the optical fiber unit 1 and the sheath 5. This makes it easy to take out the optical fiber unit 1 and is advantageous in guiding the arrival point of the crack to the short side of the optical fiber tape 2 disposed at one end of the optical fiber unit 1. is there. Here, the angle α is set in the same manner as in the first embodiment.

A fourth embodiment of the optical fiber cable of the present invention will be described with reference to FIG. FIG. 6A shows a form in which the optical fiber unit 1 is composed of a plurality of single-core optical fibers 4, and FIG. 6B shows that the optical fiber unit 1 is composed of a plurality of optical fiber tapes 2. It is a form. The optical fiber cable of the present invention shown in FIG.

In FIG. 6, the bottom of the notch 21 is a point A, and the point of the optical fiber unit 1 that is closest to the point A is a point B. At this time, when the angle formed by the line segment AB and the central axis 7 is γ, the optical fiber cable of this embodiment is provided with the notch 21 so that the angle γ is 80 degrees or less.

When the notch 21 is set in the positional relationship with the optical fiber unit 1 as described above, there is a high possibility that the crack 6 is formed from the point A to the point B. As a result, the crack 6 is smoothly connected to the longitudinal interface between the sheath 5 and the optical fiber unit 1, so that the optical fiber unit 1 can be easily removed from the sheath 5.

A fifth embodiment of the optical fiber cable of the present invention will be described with reference to FIG. The optical fiber cable of the present invention shown in FIG. 7 is provided with a notch 21, and the optical fiber unit 1 is composed of a plurality of single-core optical fibers arranged in a row adjacent to each other.

In the optical fiber cable of this embodiment, when the bottom of the notch 21 is A and the position of the optical fiber unit 1 closest to the bottom A is B, the point B is a plurality of single-core optical fibers 4 constituting the optical fiber unit 1. The notch 21 is on the interface between the single-core optical fiber 4a located at one end and the sheath 5 so that the angle δ from the line segment AB and the adjacent interface 11 is not less than 100 degrees and less than 180 degrees. Is provided.

When the notch 21 is set in the positional relationship with the optical fiber unit 1 as described above, there is a high possibility that the crack 6 is formed from the point A to the point B. As a result, the crack 6 is smoothly connected to the interface in the long side direction between the sheath 5 and the optical fiber unit 1, so that the optical fiber unit 1 can be easily removed from the sheath 5.

Further, the position of the point B is on the interface between the single optical fiber 4a located at one end and the sheath 5, and the angle δ from the adjacent interface 11 is 100 degrees or more and less than 180 degrees. This increases the probability that the crack 6 reaches the range of the angle δ, and the crack 6 divides the interface between the single-core optical fiber 4a and the sheath 5 almost evenly. 5 can be easily taken out.

The single-core optical fiber 4 constituting the optical fiber unit 1 may be set to a nominal outer diameter of 0.5 mm or more in consideration of other workability during installation. In this case, compared with a normal fiber having an outer diameter of 0.25 mm, the outer diameter of the single-core optical fiber 4 is increased, so that the conventional take-out performance is lowered. Since the crack 6 can be formed at a preferred position, the ease of work by using the large-diameter optical fiber can be enjoyed while ensuring the ease of taking out the optical fiber unit 1.

A sixth embodiment of the optical fiber cable of the present invention will be described with reference to FIG. The optical fiber cable of the present invention shown in FIG. Each of the optical fiber units 1 shown in FIGS. 8A to 8C is configured by one optical fiber tape 2 and two lights arranged in the direction of the long-side direction center line 7 of the optical fiber unit 1. The form comprised with the fiber tape 2 and the form comprised with the two-layer optical fiber tape 2 in the direction orthogonal to the long-side direction centerline 7 of the optical fiber unit 1 are shown.

In the optical fiber cable of the present embodiment, when the bottom of the notch 21 is A and the position of the optical fiber unit 1 closest to the bottom A is B, the point B is one or more lights constituting the optical fiber unit 1. A point B is provided on the short side of the optical fiber tape 2 located at one end of the fiber tape 2. And the notch 21 is provided so that the angle (alpha) between line segment AB and the central axis 7 may be set to 80 degrees or less.

When the notch 21 is set in the positional relationship with the optical fiber unit 1 as described above, there is a high possibility that the crack 6 is formed from the point A to the point B. As a result, the crack 6 is smoothly connected to the interface in the long side direction between the sheath 5 and the optical fiber unit 1, so that the optical fiber unit 1 can be easily removed from the sheath 5. In addition, since the point B is provided at a position on the short side of the optical fiber tape 2 located at one end of the optical fiber unit 1, the probability that the crack 6 will reach the short side of the optical fiber tape 2 is high. It is possible to suppress separation between the fibers tape 2, that is, destruction.

Examples of the present invention will be described below. FIG. 1 is a cross-sectional view showing one embodiment of the present invention.
In the optical fiber cable 30 of FIG. 1, an optical fiber 31 is formed to have an outer diameter of 250 μm by coating a bare optical fiber made of quartz having a diameter of 125 μm with an ultraviolet curable resin. On top of that, a colored layer made of an ultraviolet curable resin is coated for identification. The four optical fibers 31 are all covered together with an ultraviolet curable resin to constitute a four-core optical fiber tape 32. The ultraviolet curable resin layer is controlled to be 3 μm to 25 μm at the thinnest position, and has a structure that can be branched later by using an appropriate tool such as a paper file. An optical fiber unit 33 is formed by laminating two layers of the four-core optical fiber tape 32.

The tension members 3 are made of FRP of aramid fibers having a diameter of 0.5 mm, and are arranged on both sides of the center line 7 extending in the long side direction of the optical fiber unit 33. The sheath 5 is made of polyethylene, and two notches 21 are formed on the long side of the sheath 5 in the longitudinal direction of the optical fiber cable 30. The long side (width direction) of the rectangular shape of the sheath 5 is 4 mm 2 and the short side (thickness direction) is 2 mm. Here, the bottom of the notch 21 is the point A, the point of the optical fiber unit 33 closest to the point A is the point B, the center line in the long side direction of the optical fiber unit C is the angle between the straight line AB and the center line C. Each angle formed by γ and an actual crack and the center line C is defined as an angle α.

In the optical fiber cable 30 constructed as described above, five types of samples with varying notch arranged to create the 30, performs a tear for 10 samples in a temperature environment of three levels, tear the sheath 5 At that time, the case where no breakage of the optical fiber tape such as inter-center separation occurred was evaluated as ◯, the case where breakage occurred in 1 to 3 pieces, and the case where breakage occurred in 4 or more pieces were evaluated as ×. The evaluation results are shown in FIG.

As shown in FIG. 9, the angle γ and the angle α coincide with each other with a high probability, and the point B and the actual crack arrival point also coincide with each other with a high probability. When the angle α is 80 degrees or less, there is no x evaluation, and when the angle α is 45 degrees or less, all are ◯ evaluation. From the above results, in order to take out the optical fiber tape without breaking it, the angle γ is preferably set to 80 degrees or less, and more preferably set to 45 degrees or less.

FIG. 2 is a cross-sectional view showing another embodiment of the present invention.
In the optical fiber cable 40 of FIG. 2, the single-core optical fiber 41 is coated with an ultraviolet curable resin having an outer diameter of φ250 μm on a bare optical fiber made of quartz of φ125 μm, thereby improving the handling of the core wire. Therefore, an ultraviolet curable resin is further coated to have an outer diameter of φ500 μm.

In the present embodiment, the optical fiber unit 42 is configured by arranging two single-core optical fibers 41 formed as described above. The tension member 3 is made of FRP of aramid fiber having a diameter of 0.5 mm, the sheath 5 is made of polyethylene, and two notches 21 are formed on the long side of the sheath 5 in the longitudinal direction of the optical fiber cable 40. Yes. The sheath 5 has a rectangular shape, and has a long side (width direction) of 4 mm and a short side (thickness direction) of 2 mm. Here, the bottom of the notch 21 is the point A, the point of the optical fiber unit 33 closest to the point A is the point B, the center line in the long side direction of the optical fiber unit C is the angle between the straight line AB and the center line C. An angle formed between γ and point B and the adjacent interface is an angle δ, and an angle formed between an actual crack arrival point and the adjacent interface is an angle β.

In the optical fiber cable 40 configured as described above, 30 samples of 5 types each having a different notch arrangement were prepared, and 10 samples were torn in a three-level temperature environment. When the sheath 5 was torn, the case where no single-fiber optical fiber was broken was evaluated as ◯, the case where one to three pieces were broken, and the case where four pieces or more were broken as x. In addition, as shown in FIG. 13, when the sheath 5 is torn into two, the state where the optical fiber unit 43 is separated without adhering to either of the sheath pieces 51 and 52 is excellent in separability. The state in which the optical fiber unit 43 is attached to the sheath piece is defective, ◯ when all of the ten samples are good, ◯ when the three are defective, and △ when four or more are defective. evaluated. The results are shown in FIG.

As shown in FIG. 10, the angle γ and the angle α are matched with a high probability, and the angle δ and the angle β are also matched with a high probability. With respect to the presence or absence of breakage of the single-core optical fiber, no evaluation is given when the angle α is 80 degrees or less, and all evaluations are ◯ when the angle α is 45 degrees or less. With respect to the separability of the single-core optical fiber, there is no x evaluation when the angle α is 80 degrees or less, and all the evaluations are ○ when the angle α is 30 degrees or less.
From the above results, in order to take out the single-core optical fiber without breaking it, the angle β is preferably 80 degrees or less, more preferably 45 degrees or less, and further preferably 30 degrees or less.

As another embodiment, the optical fiber cable itself may have a support line. Further, the tension member and the support wire may be steel wire, fiber, etc. in addition to FRP. Furthermore, the case where a tension member is not provided may be used. The number of optical fibers and the number of stacked optical fibers in the optical fiber can be selected as appropriate. The material of the sheath can be appropriately selected from polyvinyl chloride, polyethylene, non-halogen flame retardant polyethylene, and the like.

FIG. 1 is a cross-sectional view showing one embodiment of the optical fiber cable of the present invention. FIG. 2 is a cross-sectional view showing another embodiment of the optical fiber cable of the present invention. FIG. 3 is a schematic view showing the first embodiment of the optical fiber cable of the present invention. FIG. 3A shows a form in which the optical fiber unit 1 is formed by a plurality of optical fiber tapes 2, and FIG. 3B shows that the optical fiber unit 1 is formed by a plurality of single-core optical fibers 4. It is a form. FIG. 4 is a schematic view showing a second embodiment of the optical fiber cable of the present invention. FIG. 5 is a schematic view showing a third embodiment of the optical fiber cable of the present invention. FIG. 5A is a configuration composed of one optical fiber tape 2, and FIG. 5B is composed of two optical fiber tapes 2 arranged in the direction of the long-side direction center line 7 of the optical fiber unit 1. FIG. 5C shows a configuration in which the optical fiber unit 1 is constituted by two layers of the optical fiber tape 2 in a direction perpendicular to the long-side direction center line 7. FIG. 6 is a schematic view showing a fourth embodiment of the optical fiber cable of the present invention. FIG. 6A is a form in which the optical fiber unit 1 is composed of a plurality of single-core optical fibers 4, and FIG. 6B is a diagram in which the optical fiber unit 1 is composed of a plurality of optical fiber tapes 2. It is a form. FIG. 7 is a schematic view showing a fifth embodiment of the optical fiber cable of the present invention. FIG. 8 is a schematic view showing a sixth embodiment of the optical fiber cable of the present invention. FIG. 8A is a configuration constituted by one optical fiber tape 2, and FIG. 8B is constituted by two optical fiber tapes 2 arranged in the direction of the long-side direction center line 7 of the optical fiber unit 1. FIG. 5C shows a configuration in which the optical fiber unit 1 is constituted by two layers of the optical fiber tape 2 in a direction perpendicular to the long-side direction center line 7. FIG. 9 is a table showing the results of examining the ease of taking out the optical fiber unit 33 by changing the angle α in one embodiment of the optical fiber cable of the present invention. FIG. 10 is a table showing the results of examining the ease of taking out the optical fiber unit 33 by changing the angle α in another embodiment of the optical fiber cable of the present invention. FIG. 11 is a cross-sectional view showing a configuration of a conventional optical fiber cable. FIG. 12 is a cross-sectional view showing the configuration of another conventional optical fiber cable. FIG. 13 is a schematic diagram for explaining a state in which the sheath 5 is torn into two.

Explanation of symbols

1, 33, 42, 101 ... Optical fiber unit 2, 32 ... Optical fiber tape 3, 102 ... Tension members 4, 31, 41 ... Optical fiber 5, 103 ... Sheath 6 ... · Crack 7 ··· Center line 8 ··· End 11 · · · Adjacent interface 21, 106 · · · Notch 30, 40, 100, 110 · · · Optical fiber cable 104 · · · Neck portion 105 · · · Support line

Claims (2)

An optical fiber unit in which a plurality of optical fibers are arranged in a substantially flat shape, a tension member arranged on both sides of the optical fiber unit on a center line extension in the long side direction of the optical fiber unit, the optical fiber unit and the tension member collectively coated with a V-shaped notches which are arranged one by one in a substantially flat sheath with long side both surfaces of the sheath along the long side of the optical fiber unit,
The optical fiber unit is composed of a plurality of single-core optical fibers arranged in a row adjacent to each other, and the single-core optical fiber is coated with an ultraviolet curable resin with an outer diameter of φ250 μm on a bare optical fiber of φ125 μm A single-core optical fiber having an outer diameter of 0.5 mm and further coated with an ultraviolet curable resin in order to improve the handleability of the optical fiber.
When the bottom of the notch is point A and the point closest to the point A of the optical fiber unit is point B, the angle γ formed by the long-side center line of the optical fiber unit and the line segment AB is 30 degrees or more and 80 An optical fiber cable characterized by being less than or equal to a degree.   2. The optical fiber cable according to claim 1, wherein the point B is a position where an angle δ from an adjacent interface of a single-core optical fiber located at one end of the optical fiber unit is 100 degrees or more and 150 degrees or less. An optical fiber cable characterized by that.

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