JP2013156536A - Optical fiber tape and optical fiber cable - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical fiber tape capable of suppressing light loss increase on optical fibers, obtaining stable light loss characteristic, obtaining sufficient long-term reliability by reduction of distortion applied to the optical fibers, and facilitating connecting operation in the case of a single-core separation work using a brush-like tool.SOLUTION: The optical fiber tape comprises single-core coated optical fibers of three or more cores with a coating applied on an outer circumference and a gluing part for integrating two adjacent single core coated optical fibers that are two-dimensionally separated from each other in a longitudinal direction and a width direction of the single core coated optical fibers. A longitudinal length Lof a part of the gluing part in contact with surfaces of the single core coated optical fibers is longer than a longitudinal length Lof a part of the gluing part at an arbitrary position between the adjacent single core coated optical fibers.

Description

  The present invention relates to an optical fiber tape and an optical fiber cable. More specifically, the present invention relates to an optical fiber tape and an optical fiber cable capable of performing a single-core separation operation while suppressing an increase in optical loss generated in the optical fiber.

  When constructing an access network, several types of optical fiber cables are connected, and the optical fiber is wired to each user. In addition, in this construction, in the area close to the telecommunications carrier equipment building, there may be a batch connection in units of optical fiber tapes mainly composed of a plurality of optical fibers, while the area to be wired to each user In some cases, the optical fiber tape is separated into single fibers (single fiber separation) and connected in units of one fiber. Here, a general optical fiber tape has a structure in which a plurality of single-core coated optical fibers coated on the outer periphery of the optical fiber are arranged in a planar shape, and the entire outer periphery is collectively coated with a resin (hereinafter referred to as “optical fiber”) In some cases, it may be referred to as “batch coated optical fiber tape”.

  Also, when separating the optical fiber tape from a single core, if the optical fiber constituting the optical fiber tape is used for communication, if the optical fiber is bent or twisted more than a certain amount, the optical loss increases or Since there is a possibility of causing communication failure due to disconnection, it is very important to perform single-core separation without causing an increase in optical loss. For this reason, conventionally, the optical fiber tape is held in a substantially straight state in the longitudinal direction, and a sharp blade of a single-fiber separating tool is inserted between the single-core coated optical fibers of the held optical fiber tape. A single blade was separated by moving a long blade in the longitudinal direction of the single-core coated optical fiber. (For example, see Patent Document 1.)

  In addition, for the purpose of increasing the diameter and density of optical fiber cables, a plurality of single-core coated optical fibers are arranged in a plane, and an adhesive portion for adhering only two adjacent optical fibers is formed in the longitudinal direction of the optical fiber. An optical fiber cable on which an optical fiber tape provided intermittently (hereinafter referred to as “intermittently bonded optical fiber tape”) is mounted has been proposed (see, for example, Patent Document 2). By adopting such a structure for the optical fiber cable, it is possible to secure a small diameter and high density, ensure optical loss characteristics and long-term reliability, and connect a plurality of optical fibers at once.

  However, the intermittently bonded optical fiber tape used in such an optical fiber cable has a plurality of optical fibers arranged in a plane and is collectively covered like the above-described collectively coated optical fiber tape. Because it is not such a structure, each single-core coated optical fiber can move independently in a portion where the single-core coated optical fibers are not connected to each other. In some cases, the distance between the coated optical fibers is not constant. For this reason, when a conventionally used single-core separating tool is used, there is a problem that the single-fiber coated optical fiber is excessively bent or damaged by the blade, and in some cases, a disconnection is caused.

  As a technique for single-fiber separation of such an intermittently bonded optical fiber tape, there is a separation method using a brush-like member in which a linear material is bundled (hereinafter sometimes referred to as “brush-like tool”). In this separation method, by pressing the brush-shaped tool from the upper surface of the intermittently bonded optical fiber tape, the linear material enters the gap between the bonded portions of the single-core coated optical fibers, and the brush-shaped tool is further moved. In this method, the adhesive portion is broken or peeled off from the single-core coated optical fiber by sliding in the longitudinal direction of the optical fiber tape and separated into individual single-core coated optical fibers. And by using this brush-like tool, it was possible to separate the intermittently bonded optical fiber tape into a single core.

Japanese Patent No. 3802828 Japanese Patent No. 4619424

  However, when the intermittently bonded optical fiber tape is separated into a single core using a brush-like tool, there are various problems as follows.

  First, as a first problem, when the intermittently bonded optical fiber tape is separated into a single core using a brush-like tool, the adhesion between the bonded portion and the single-core coated optical fiber and the strength of the bonded portion are large. In addition, even if the brush-like tool is slid in the longitudinal direction of the optical fiber tape, the bonded part does not break or peel off from the single-core coated optical fiber, and the optical fiber tape is bent to increase the optical loss of the internal optical fiber. There was a risk of causing it. This is because the adjacent single-core coated optical fibers of the intermittently bonded optical fiber tape need to be integrated with the intermittently disposed adhesive part, so the adhesive part needs to ensure a certain level of adhesion and strength. Because there is.

  Next, as a second problem, in the work of separating the optical fiber tape mounted on the small-diameter high-density optical fiber cable as described in Patent Document 2, it is mounted on the optical fiber cable at a high density. It is necessary to take out the optical fiber tape to be separated from the optical fiber tape in advance, but the optical fiber tapes or the optical fiber units may get tangled during the removal. There was a problem of causing an increase in light loss.

  Such a problem is caused by the structure of the optical fiber cable. For the purpose of reducing bending and distortion, an optical fiber unit or an optical fiber unit in which a plurality of optical fiber tapes are bundled (hereinafter referred to as “optical fiber”). Is sometimes twisted with a certain length and mounted inside the optical fiber cable. By inserting such a twist, the optical fiber tapes or the optical fiber units are entangled with each other. Is. Here, the length of one period of twisting between optical fiber tapes or between optical fiber units is called “twisting pitch”, and the shorter the twisting pitch is, the more effective it is to suppress distortion caused by bending. Therefore, for example, a twist of about one rotation is applied to the length of the optical fiber cable of about 300 mm (in this example, “twisting pitch is about 300 mm”).

  When performing a single fiber separation operation on an optical fiber tape mounted on such an optical fiber cable, it is necessary to remove the twist between the optical fiber tapes or between the optical fiber units in advance. In this case, the twist is moved to one side and removed by hand until the brush-shaped tool slides outside. On the other hand, when the twist pitch is shorter than the length of the range in which the brush-like tool is slid, when the twist is brought close to one end, the twist of one rotation or more is concentrated at that portion, and the twist becomes tight. Such a problem was to occur.

  As a third problem, in the operation of separating the intermittently bonded optical fiber tape into a single core, as the brush-like tool is slid in the longitudinal direction while being pressed against the optical fiber tape, the unit length of the optical fiber tape is increased. There is a problem in that the amount of twisting increases, causing an increase in optical loss. Similar to the second problem, this problem is caused by the structure of the optical fiber cable, and the unit of the optical fiber (optical fiber unit) in which the optical fiber tape or a plurality of optical fiber tapes are bundled is constant. This is because it is twisted in length and mounted in an optical fiber cable. When the optical fiber tapes or the optical fiber units are twisted together, depending on the structure of the optical cable, the optical fiber tape alone is twisted. The length of one cycle of the twist as the single optical fiber tape is defined as “twist pitch”.

  For example, when the twist pitch is about 300 mm as described above, if the optical fiber tapes are simply twisted together, the twist pitch of the optical fiber tape is also about 300 mm. When performing a single-fiber separation operation on an optical fiber tape mounted on such an optical fiber cable, it is necessary to remove the twist of the optical fiber tape in advance. As a method of removing the twist, for example, the twist is moved to one side and removed to the outside of the range in which the brush-like tool is slid. However, in the case where the twist pitch is shorter than the length of the range in which the brush-like tool is slid, when the twist is brought to one end, the twist of one rotation or more is concentrated at that portion, and the twist becomes tight, as described above. Was supposed to cause problems.

  The present invention was made in view of the above circumstances, and even when performing a single-core separation operation using a brush-like tool, it is possible to suppress an increase in optical loss that occurs in an optical fiber, and a stable optical loss characteristic is obtained. Another object of the present invention is to provide an optical fiber tape and an optical fiber cable that have sufficient long-term reliability by reducing strain applied to the optical fiber and that can be easily connected.

In order to achieve the above object, the optical fiber tape of the present invention has a length L ₁ in the longitudinal direction of a portion in contact with the surface of a single-core coated optical fiber of an adhesive portion between adjacent single-core coated optical fibers. It was made longer than length L ₂ of the longitudinal direction of the adhesion part in arbitrary positions.

Specifically, the present invention provides a single-core coated optical fiber having three or more cores coated on the outer periphery of the optical fiber and two-dimensionally spaced apart from each other in the longitudinal direction and the width direction of the single-core coated optical fiber. And an adhesive portion that integrates the two single-core coated optical fibers adjacent to each other, and a longitudinal direction of a portion of the adhesive portion that is in contact with the surface of the single-core coated optical fiber The length L ₁ of the optical fiber tape is longer than the length L ₂ in the longitudinal direction of the adhesive portion at an arbitrary position between the adjacent single-core coated optical fibers.

In the optical fiber tape of the present invention, the length L ₂ in the longitudinal direction of the adhesive portion at an arbitrary position between the adjacent single-core coated optical fibers is substantially equal to that of the adjacent two-core single-core optical fibers. It is characterized by being the shortest in the middle.

  In the optical fiber tape of the present invention, a linear material is inserted into a portion where an adhesive portion between the two adjacent single-core coated optical fibers is not disposed, and the linear material is elongated in the longitudinal direction of the optical fiber tape. The force required to move the linear member is 1 N or less when the adhesive part is peeled off from the single-core coated optical fiber or the adhesive part is broken. .

  In order to achieve the above object, the optical fiber cable of the present invention is an optical fiber cable including the optical fiber tape described above.

  Specifically, the present invention is an optical fiber cable characterized in that a plurality of the optical fiber tapes according to any one of the above are twisted together and the outer periphery of the assembled optical fiber tape is covered with a jacket. It is.

  The optical fiber cable of the present invention is characterized in that a twist pitch of the optical fiber tape is 500 mm or more.

  An optical fiber cable of the present invention is formed by forming an optical fiber unit in which a plurality of optical fiber tapes according to any one of the above are twisted and assembled, and a plurality of the optical fiber units are twisted and assembled to each other. The outer periphery of the optical fiber unit is covered with a jacket.

  The optical fiber cable of the present invention is characterized in that a twist pitch of the optical fiber unit is 500 mm or more.

  The optical fiber cable of the present invention is characterized in that a twist pitch of the optical fiber tape is 500 mm or more.

An optical fiber cable according to the present invention includes a plurality of the optical fiber tapes according to any one of the above, and a jacket covering an outer periphery of the assembled optical fiber tape, with respect to a center of the optical fiber cable. An optical fiber cable in which two strength members are arranged on the jacket so as to be symmetrical with each other along the length direction, and the optical fiber is bent when the optical fiber cable is bent at a bending radius R. The tensile strain ε applied to is represented by the following formula (1).
ε ≧ {D + (d / 2)} / R (1)
ε: Tensile strain applied to the optical fiber when the optical fiber cable is bent D: Light mounted at a position farthest away from the plane connecting the centers of the two strength members in the cross section of the optical fiber cable Distance to the center of the fiber (mm)
d: Outer diameter (mm) of single-core coated optical fiber used for optical fiber tape
R: Bending radius applied to optical fiber cable (mm)

  The above inventions can be combined as much as possible.

  The optical fiber tape of the present invention is an optical fiber tape that suppresses an increase in optical loss in a single-fiber separation operation and provides stable optical characteristics.

  In addition, the optical fiber cable of the present invention is an optical fiber cable in which the optical fiber tape of the present invention described above is mounted inside, and an increase in optical loss of the optical fiber can be suppressed even in a single core separation operation.

It is the schematic which showed the one aspect | mode of the optical fiber tape of this invention. It is AA sectional drawing of FIG. It is BB sectional drawing of FIG. An explanatory diagram showing a relationship between L ₁ and L _2, a diagram L ₁ showed longer construction than L _2. An explanatory diagram showing a relationship between L ₁ and L _2, a diagram L ₂ showed a longer construction than L _1. FIG. 6 is a schematic view showing another aspect of the shape of the bonding portion in FIG. It is the front view which showed the one aspect | mode of the optical fiber tape of this invention. It is explanatory drawing which showed an example of the single core isolation | separation operation | work by a linear material. It is the schematic which showed the structural example of the optical fiber cable. It is the schematic which showed the state which removed some outer jackets of the optical fiber cable. In FIG. 10, it is the schematic which showed the state which brought the twist of optical fiber tapes to one side. It is the schematic which showed the relationship between the stripping length and the twist pitch in the single fiber separation operation | work of an optical fiber cable. It is the schematic which showed the optical fiber tape of the twisted state. In FIG. 13, it is the schematic which showed the state which brought the twist of the optical fiber tape to one side. It is the schematic which showed the other aspect of the optical fiber cable of this invention, Comprising: The optical fiber cable provided with the tension body. It is the schematic which showed an example of the cross-section of the optical fiber cable which can mount the optical fiber tape of this invention. It is the schematic which showed an example of the cross-section of the optical fiber cable which can mount the optical fiber tape of this invention. It is the schematic which showed an example of the cross-section of the optical fiber cable which can mount the optical fiber tape of this invention. It is the schematic which showed an example of the cross-section of the optical fiber cable which can mount the optical fiber tape of this invention. It is the schematic which showed an example of the cross-section of the optical fiber cable which can mount the optical fiber tape of this invention. It is the schematic which showed an example of the cross-section of the optical fiber tape of this invention. It is a figure explaining the relationship between the optical loss increase characteristic at the time of single fiber separation work, and the force moved to the longitudinal direction of the optical fiber tape.

  Embodiments of the present invention will be described with reference to the accompanying drawings. The embodiments described below are examples of the present invention, and the present invention is not limited to the following embodiments. In the present specification and drawings, the same reference numerals denote the same components. Each embodiment can be combined as much as possible.

(Optical fiber tape)
The optical fiber tape of the present invention is arranged such that three or more single-core coated optical fibers coated on the outer periphery of the optical fiber and two-dimensionally separated from each other in the longitudinal direction and the width direction of the single-core coated optical fiber, A length L ₁ in the longitudinal direction of a portion of the adhesive portion that is in contact with the surface of the single-core coated optical fiber. but longer than the longitudinal length L ₂ of the bonded portion at any position between the single-core coated optical fiber adjacent.

  1 is a schematic view showing an embodiment of the optical fiber tape of the present invention, FIG. 2 is a cross-sectional view taken along line AA in FIG. 1, and FIG. 3 is a cross-sectional view taken along line BB in FIG.

  An optical fiber tape 1 of the present invention shown in FIG. 1 has three or more single-core-coated optical fibers 11 (in FIG. 1, a four-core embodiment arranged in a plane) and two adjacent fibers. The single-core coated optical fiber 11 is integrated, and the bonding portion 12 is two-dimensionally arranged in the longitudinal direction and the width direction. In this way, only two adjacent single-core coated optical fibers 11 are bonded by the bonding portion 12.

  The single-core coated optical fiber 11 is obtained by coating the outer periphery of an optical fiber (not shown) in the longitudinal direction with, for example, an ultraviolet curable resin coating. The adhesive portion 12 made of resin or the like can be formed from various resin materials such as an ultraviolet curable resin, a thermoplastic resin, and a thermosetting resin that integrate the single-core coated optical fibers 11 together. In addition, in order to give discriminability to the optical fiber tape 1, the bonding portion 12 may be colored or the like.

  As shown in FIG. 1 and FIG. 2, the bonding portion 12 constituting the optical fiber tape 1 is formed by integrating two adjacent single-core coated optical fibers 11 arranged in a plane, and connecting the bonding portions 12 to each other. Are arranged apart from each other in the longitudinal direction and the width direction of the optical fiber tape 1. In addition, in FIG. 1 etc., a part of part in which the adhesion part 12 in the optical fiber tape 1 is not formed is shown as the non-adhesion part 13.

In the optical fiber tape 1 of the present invention, as shown in FIG. 3, the length of the bonding portion 12 in the longitudinal direction of the optical fiber is L, and the length of the portion of the bonding portion 12 that is in contact with the surface of the single-core coated optical fiber 11. The length L ₁ in the direction is formed to be longer than the length L ₂ in the longitudinal direction of the bonding portion 12 at an arbitrary position between the adjacent single-core coated optical fibers 11.

It will be described with reference to FIGS. 4 and 5 the relationship of such L ₁ and the length of L _2. 4 and 5 are explanatory views showing a relationship between _{L 1} and _{L 2,} Fig. 4 _{in which L 1} showed longer construction than _{L 2,} FIG. 5 is configured _{L 2} is longer than _{L 1} FIG.

As shown in FIG. 4, a linear material 2 of a brush-like tool (not shown) is provided between the single-core coated optical fibers 11 by making L _{1 of the} bonding portion 12 longer than L ₂ as in the present invention. When the optical fiber tape 1 is slid in the longitudinal direction of the optical fiber tape 1 and separated from the single core, stress concentrates on the shortest portion of L ₂ shorter than L ₁ , so that the adhesive portion 12 is broken or the adhesive portion 12 is single core. It will peel from the coated optical fiber 11 (hereinafter sometimes referred to as “break” or the like), and bending of the optical fiber tape 1 will cause an increase in optical loss in the single-core coated optical fiber 11 inside. Can be prevented.

On the other hand, as shown in FIG. 5, when L ₂ of the bonding portion 12 is longer than L _{1, the} linear material 2 of the brush-like tool (not shown) may enter the boundary surface between the single-core coated optical fiber 11 and the bonding portion 12. As a result, bending stress is likely to be applied to the single-core coated optical fiber 11, which may cause an increase in optical loss. L ₂ may be made shorter than the length of L ₁ . The bonding part 12 can make it difficult for the wire 2 to enter between the single-core coated optical fiber 11 and the bonding part 12 by making L ₁ sufficiently longer than L ₂ .

Incidentally, in the bonding portion 12 of the optical fiber ribbon 1 of the present invention, the shortest of the longitudinal length L ₂ of the bonded portion 12 at any position between the single-core coated optical fiber 11 adjacent It is preferable that the portion to be L _min is formed at a substantially intermediate position between the adjacent single-core coated optical fibers 11. Thus, when separated into single fibers, the stress is easily concentrated by partial of L _min, the adhesive portion 12 so that the breakage is done reliably.

FIG. 6 is a schematic view showing another aspect of the shape of the bonding portion 12 in FIG. As shown in FIG. 6, the linear material 2 of the brush-like tool (not shown) is formed in the longitudinal direction of the optical fiber tape 1 by forming the ends of both ends in the longitudinal direction which become L _min of the bonding portion 12 in an acute angle shape. When it is slid in the direction and separated into single cores, it is preferable because stress can be efficiently concentrated on the portion of L _min and the bonded portion 12 can be easily broken.

  FIG. 7 is a front view showing one embodiment of the optical fiber tape 1 of the present invention. As shown in FIG. 7, in the optical fiber tape 1 of the present invention, the surface where the bonding portion 12 and the single-core coated optical fiber 11 are in contact is the surface of the bonding portion 12 that is disposed apart in the longitudinal direction. , It is possible to prevent the wire 2 (not shown in the figure) from entering between the single-core-coated optical fiber 11 and the bonding portion 12, and to increase the optical loss during single-core separation. Can be suppressed.

  FIG. 8A and FIG. 8B are explanatory views showing an example of single-core separation work by the linear material 2. FIG. 8A shows a state before implementation, and FIG. 8B shows a state during implementation. In the bonding part 12 constituting the optical fiber tape 1 of the present invention, if the strength of the bonding part 12 or the adhesion between the bonding part 12 and the single-core coated optical fiber 11 is too high, as shown in FIG. When the linear material 2 of the brush-like tool (not shown) is slid in the longitudinal direction of the optical fiber tape 1 and separated into a single core, the optical fiber tape is passed when the linear material 2 passes through the bonding portion 12. 1 may be subjected to bending stress to increase optical loss. Therefore, it is necessary to make the strength of the bonding portion 12 equal to or less than a certain value and to break the bonding portion 12 before bending stress is applied to the optical fiber tape 1.

  Here, FIG. 22 shows the result of confirming the relationship between the optical loss increasing characteristic at the time of the single-fiber separation work using the linear material 2 and the force for moving the optical fiber tape 1 in the longitudinal direction.

  Specifically, the linear member 2 having an outer diameter of φ90 μm is inserted into a portion where the bonding portion 12 between the two adjacent single-core coated optical fibers 11 is not disposed, and the linear member 2 is optically The force for moving the linear member 2 is moved in the longitudinal direction of the fiber tape 1 at a speed of 500 mm / min to separate the bonded portion 12 from the single-core coated optical fiber 11 or to break the bonded portion 12. This is the result of confirming and evaluating the increase in optical loss at that time.

Regarding the criteria for the allowable increase in optical loss, Y.E. Yamada, et al. , “Ultra-High-Density Optical Fiber Cable With More Than 3 Fiber / mm ² ”, 55th IWCS, pp. 410-414 (2006). In the case where the wavelength loss is 1.5 dB at a wavelength of 1.55 μm and the increase in optical loss is 1.0 dB or less, the value is “None (within tolerance)”. Evaluated as “existing (out of tolerance)”. The results are shown in FIG.

(Stress and light loss increase)
From the results shown in FIG. 22, it can be confirmed that an increase in optical loss can be suppressed to 1.0 dB or less in an optical fiber tape having a force of 1 N or less when the linear member 2 passes. Therefore, it is preferable to form the adhesion part 12 so that the force when the linear material 2 passes becomes 1 N or less.

(Optical fiber cable)
Next, an aspect of the optical fiber cable 3 of the present invention will be described.
FIG. 9 is a schematic view showing a structural example of an optical fiber cable. As shown in FIG. 9, the optical fiber cable 3 has an outer periphery formed by extrusion-coating a thermoplastic resin such as polyethylene resin or polyvinyl chloride resin on the outer periphery of an assembly 14 in which a plurality of optical fiber tapes 1 are assembled. The cover 31 is covered. The outer periphery of the optical fiber tape assembly 14 may be covered with a core holding winding tape (not shown) having water absorption or the like. The optical fiber tape 1 mounted inside the optical fiber cable 3 is generally twisted to form an optical fiber tape assembly 14 in order to suppress strain applied to the optical fiber when the optical fiber cable 3 is bent. ing. The optical fiber tape 1 mounted inside the optical fiber cable 3 includes a case where a plurality of optical fiber tapes 1 are twisted to form an assembly 14 and a case where a plurality of optical fiber tapes 1 are straight or twisted together. In some cases, a plurality of optical fiber units 4 that are assembled together are twisted to form an assembly 14. In any case, the optical fiber tape 1 mounted inside is twisted.

  On the other hand, when performing single-core separation work on site, any one optical fiber tape 1 to be worked is taken out from the optical fiber tape 1 that is densely mounted inside the optical fiber cable 3. become. FIG. 10 is a schematic view showing a state in which a part of the jacket 31 of the optical fiber cable 3 is removed, and FIG. 11 shows a state in which the twists of the optical fiber tapes 1 are brought to one side in FIG. FIG.

  When a single optical fiber tape 1 is taken out from the optical fiber cable 3 and a single-core separation operation is performed, generally, twisting of the optical fiber tapes 1 from the state of FIG. 10 to the state of FIG. It is necessary to move in the direction of the arrow in FIG. In this case, the twisted portions of the optical fiber tapes 1 are tightly twisted, and the optical fiber tape 1 or the single-core coated optical fiber 11 constituting the optical fiber tape 1 is excessively bent. Therefore, there is a possibility that the optical loss of the single-core coated optical fiber 11 is increased.

  For this reason, in the optical fiber cable 3 of the present invention, as shown in FIG. 12, with respect to the optical fiber tape 1 mounted therein, a plurality of optical fiber tapes 1 or a plurality of optical fiber units 4 are provided. It is preferable to set the length of the twist pitch when twisting together to be equal to or greater than the peel length of the jacket 31. FIG. 12 is a schematic view showing the relationship between the stripping length and the twisting pitch in the single-fiber separation operation of the optical fiber cable 3, and a plurality of optical fiber tapes 1 or a plurality of optical fiber units 4 are twisted together. By setting the length of the twist pitch to be equal to or greater than the stripping length, even when the twists of the optical fiber tapes 1 are brought to one side, the twists to be gathered are sufficiently reduced, thereby suppressing an increase in optical loss. Thus, the optical fiber tape 1 can be taken out. Such a twist pitch may be longer than the stripping length of the outer cover 31 in the single core separation work, but generally, the stripping length of the outer cover 31 in the single core separation work is about 500 mm, and therefore should be longer than this length. Is particularly preferred.

  FIG. 13 is a schematic view showing the optical fiber tape 1 in a twisted state, and FIG. 14 is a schematic view showing a state in which the twist of the optical fiber tape 1 is moved to one side in FIG. As described above, since the optical fiber tape 1 is twisted and mounted on the structure of the optical fiber cable 3, the optical fiber tape 1 is mounted in a twisted state as shown in FIG. Will be. When the optical fiber tape 1 in such a twisted state is separated into single fibers, the single fiber separation tool 21 (brush-like tool or the like) is moved in the longitudinal direction of the optical fiber tape 1 as shown in FIG. As a result, the twisted portion becomes tighter, resulting in a twist of several rotations, an increase in optical loss, and normal single-fiber separation may not be achieved.

  For this reason, in the optical fiber cable 3 of the present invention, the length of the torsion pitch of the optical fiber tape 1 (or the optical fiber unit 4) is set to the strip length of the outer cover 31 for the optical fiber tape 1 mounted inside. It is preferable to set it to more than this. By setting the length of the torsion pitch to be equal to or greater than the stripping length of the jacket 31, the twist of the taken optical fiber tape 1 can be suppressed to one rotation or less. It is difficult, the optical fiber tape 1 can be taken out while suppressing an increase in optical loss, and a normal single-core separation operation can be performed. Such a twisting pitch may be shorter than the stripping length of the outer cover 31 in the single-core separation work, but as described above, the stripping length of the outer cover 31 in the single-core separation work is generally about 500 mm. It is particularly preferable to make it shorter than the length.

  In the optical fiber cable 3 of this aspect described above, the twist pitch when twisting a plurality of optical fiber tapes 1 or a plurality of optical fiber units 4 is longer than the stripping length of the jacket 31 in the single-core separation operation. Alternatively, by making the twist pitch of the optical fiber tape 1 longer than the stripping length of the jacket 31 in the single-fiber separation operation, the optical fiber tape 1 can be controlled while suppressing an increase in optical loss even if the single-fiber separation operation is performed. The optical fiber cable 3 can be taken out and can be separated normally.

Next, another aspect of the optical fiber cable 3 of the present invention will be described.
In consideration of only the twisting and twisting of the optical fiber tapes 1 as described above, the optical fiber tape 1 mounted inside the optical fiber cable 3 is preferably mounted straight so that no twisting occurs. On the other hand, even in this case, when a bending stress is applied to the optical fiber cable 3, the single-core coated optical fiber mounted on the outside of the bent optical fiber cable 3 (see FIG. 15 described later). 11, a tensile strain is applied, and a compressive strain is applied to the single-core coated optical fiber 11 mounted inside the bend (see FIG. 15 described later). Further, the tensile strain ε is obtained geometrically by the following formula (2).
ε = {D + (d / 2)} / R (2)

  Here, in Formula (2), D is the distance (mm) from the neutral plane of the bending of the optical fiber cable 3 to the center of the single-core coated optical fiber 11, and d is the outer diameter (mm) of the single-core coated optical fiber 11. ) And R are bending radii (mm) of the optical fiber cable 3, respectively.

  The D and R will be described with reference to the drawings. FIG. 15 is a schematic view showing an optical fiber cable including the strength member 32. In the figure, in addition to the sectional structure diagram, an AA sectional view and a diagram viewed from the B direction in the sectional structure diagram are also shown. When a plurality of optical fiber tapes 1 are assembled as shown in FIG. 15 and an outer sheath 31 is applied to the outer periphery to form an optical fiber cable 3, two strength members 32 are attached to the outer sheath 31. In the optical fiber cable 3 arranged so as to be symmetrical to each other along the length direction with respect to the center of the optical fiber cable 3, the surface connecting the centers of the two strength members 32 is a neutral surface of bending. The distance to the center of the single-core coated optical fiber 11a mounted at the position farthest in the direction orthogonal to the neutral plane of the bending is the distance D (see FIG. 15).

  Further, the allowable bending radius R is determined by the length of the radius R of the inscribed circle S when the optical fiber cable 1 is bent as shown in FIG.

From the above equation (2) and FIG. 15, it can be seen that the strain (ε) becomes smaller as the single-core coated optical fiber 11 mounted at a position where the distance from the neutral plane of the bending of the optical fiber cable 3 is shorter. Therefore, practically, when the bending radius applied to the optical fiber cable 3 is R, the tensile strain ε applied to the single-core-coated optical fiber 11 when the optical fiber cable 3 is bent has the relationship of Equation (2). According to the following formula (1), the distance D may be determined so that the allowable tensile strain for designing long-term reliability is ε or less.
ε ≧ {D + (d / 2)} / R (1)

  As described above, the optical fiber cable 3 of the present invention has the above-described structure, so that the tensile strain characteristics of the optical fiber cable 3 can be ensured, and the increase in optical loss of the optical fiber can be suppressed even by single fiber separation work. Thus, the optical fiber cable 3 capable of performing a single core separation operation is obtained.

  The embodiment described above is an example of the implementation of the present invention, and the present invention is not limited to such an embodiment.

  For example, since the optical fiber tape 1 of the present invention is an optical fiber tape 1 in which an adhesive portion 12 is intermittently formed in order to integrate two adjacent single-core coated optical fibers, Compared to the fiber tape 1, it can be mounted on the optical fiber cable 3 at a higher density. In addition, the optical fiber tape 1 of the present invention can be mounted on an optical fiber cable 3 having an arbitrary structure. By optimizing the details of the structure of the optical fiber cable 3, transmission characteristics and mechanical characteristics can be obtained. The general characteristics required for the optical fiber cable 3 such as workability and manufacturability can be satisfied.

  Therefore, for example, by mounting on the optical fiber cable 3 having a cross-sectional structure as shown in FIG. 16 to FIG. 20, an optical fiber cable having a smaller diameter and a higher density can be realized, and the optical fiber of the present invention. The effect which the tape 1 show | plays can also be exhibited. It can also be used as an optical fiber cable 3 according to another aspect of the present invention. In the following description, the assembled optical fiber tape 1 is described as being mounted. However, an optical fiber unit 4 in which the assembled optical fiber tapes 1 are further assembled may be mounted.

  16-20 is the schematic which showed an example of the cross-section of the optical fiber cable 3 which can mount the optical fiber tape 1 of this invention. 16 to 20, 3 is an optical fiber cable, 35 is a space for mounting the optical fiber tape of the present invention, and 31 is a jacket.

  The optical fiber cable 3 shown in FIG. 16 has a space 35 (hereinafter sometimes referred to as “mounting space 35”) in which the optical fiber tape 1 of the present invention is mounted disposed in the center of the optical fiber cable 3 and is The two strength members 32 disposed on the cover 31 are disposed so as to be symmetrical with each other along the length direction with respect to the center of the optical fiber cable 3.

  The optical fiber cable 3 shown in FIG. 17 has a mounting space 35 disposed at the center of the optical fiber cable 3 as in FIG. A buffer material 36 is interposed between the mounting space 35 and the outer cover 31 so as to be symmetrical with each other along the length direction with respect to the center of the housing. Such cushioning material 36 or the like may be interposed as a press-wound tape.

  The optical fiber cable 3 shown in FIG. 18 uses a spacer (slot rod) 37 to place one strength member 32 in the center of the optical fiber cable 3 or the spacer 37, and around the spacer 37, a plurality of tension members 32 are arranged. The slot 38 is formed in the longitudinal direction to form a mounting space 35.

  In the optical fiber cable 3 shown in FIG. 19, a single tensile body 32 is arranged in the center of the optical fiber cable 3, and a plurality of optical fiber tapes 1 (FIG. 19) into which the optical fiber tape 1 can be inserted in the longitudinal direction as a mounting space 35. 19 is a structure in which six tubes 39) are arranged in the longitudinal direction around the tensile body 2,

  The optical fiber cable 3 shown in FIG. 20 has a substantially rectangular cross-sectional shape, and the mounting space 35 is disposed in a rectangular shape at the center of the optical fiber cable 3, and two strength members disposed in the jacket 31. 32 are arranged so as to be symmetrical with each other along the length direction with respect to the center of the optical fiber cable 3.

  The cross-sectional structure of the optical fiber cable 3 shown in FIGS. 16 to 20 described above is a basic structure for mounting the optical fiber tape 1, and a function according to the usage method and environment of the optical fiber cable 3 is added. be able to.

  Specifically, for example, waterproof performance can be imparted by mounting a water stop material inside the optical fiber cable 3. Moreover, by integrating with a support body such as a steel wire in parallel with the optical fiber cable 3, a self-supporting function can be provided so that it can be negotiated independently between the utility poles. Furthermore, by providing a pipe-shaped member or partition wall made of a high-strength material such as a metal material or nylon outside the space (mounting space) 35 where the optical fiber tape 1 is mounted, a flying object or a living thing can be obtained. It is possible to improve resistance to attacks from

  Further, the cross-sectional structure and cross-sectional shape of the optical fiber tape 1 are further reduced in order to reduce the increase in optical loss during single-core separation, or to optical fibers such as high-density mounting, connection workability, and core line alignment. Various characteristics can be improved by appropriately changing in consideration of other characteristics required for the tape 1, various characteristics required for the optical fiber cable 3, manufacturability, and the like. Hereinafter, an example of a cross-sectional structure of the optical fiber tape 1 is shown in FIG.

  FIG. 21 is a schematic view showing an example of a cross-sectional structure of the optical fiber tape 1 of the present invention. As shown in FIGS. 21A to 21D, the bonding portion 12 may be formed in the vicinity of a boundary portion between two adjacent single-core coated optical fibers 11, as shown in FIG. ) And FIG. 21 (f), the adhesive portion 12 may be formed so as to surround the entire periphery including the vicinity of the boundary surface between two adjacent single-core coated optical fibers 11.

  21 (a) to 21 (d), from FIG. 21 (a) to FIG. 21 (b) and further to FIG. 21 (c), as well as FIG. 21 (d) to FIG. 21 (e) and further to FIG. 21 (f), the bonding portion is formed so that the cross-sectional area of the bonding portion 12 is increased. In FIGS. 21 (a) and 21 (b), the bonding portion is formed. 12 is lower than the outer surface of the single-core coated optical fiber 11 in a cross-sectional view, and in FIG. 21C, the bonding portion 12 is formed so as to rise beyond the outer surface of the single-core coated optical fiber 11. Further, in FIG. 21 (d), the bonding portion 12 is formed so as to be substantially the same height as the outer surface of the single-core coated optical fiber 11.

  In FIG. 21 (e) and FIG. 21 (f), in FIG. 21 (e), the bonding portion 12 is formed so that the outline of the single-core coated optical fiber 11 appears in a sectional view, and FIG. The adhesive portion 12 of the portion and the adhesive portion 12 of the outer surface portion are flat, and are formed so that a step difference between the single-core coated optical fiber 11 and the boundary portion does not appear.

  The bonding portion 12 is formed in a state in which two adjacent single-core coated optical fibers 11 are in contact (adjacent) as shown in the left diagrams of FIGS. 21 (a) to 21 (f). Alternatively, as shown in the drawings on the right side of FIGS. 21 (a) to 21 (f), two adjacent single-core coated optical fibers 11 are separated from each other, and an interval is formed. You may form in the state which the part 12 interposes.

  16 to 21 shown as the cross-sectional structure of the optical fiber cable 3 and the above-described mode of FIG. 21 shown as the cross-sectional structure of the optical fiber tape 1 are merely examples, and are limited to the modes shown therein. Any cross-sectional structure can be adopted.

  The present invention can be applied to optical cable laying work.

DESCRIPTION OF SYMBOLS 1 Optical fiber tape 11 Single core covering optical fiber 11a Single core covering optical fiber mounted in the position furthest away from the bending neutral plane 12 Adhesive part 13 Non-adhesion part 14 Assembly of optical fiber tape 2 line Shape material 21 Single-core separation tool 3 Optical fiber cable 31 Outer sheath 32 Strength member 35 Space for mounting optical fiber tape (mounting space)
36 Buffer material, etc. 37 Spacer (slot rod)
38 slot 39 tube 4 optical fiber unit L length of the optical fiber in the longitudinal direction of the bonded portion S inscribed circle D distance from the neutral plane of the bending of the optical fiber cable to the center of the single-core coated optical fiber

Claims (9)

A single-core coated optical fiber having three or more cores coated on the outer periphery of the optical fiber;
An optical fiber tape comprising: an adhesive portion that is arranged two-dimensionally apart from each other in the longitudinal direction and the width direction of the single-core coated optical fiber, and integrates the two single-core coated optical fibers adjacent to each other. ,
The longitudinal length L ₁ of the portion in contact with the surface of the single-core coated optical fibers of the adhesive portion, a longitudinal length of the adhesive portion at any position between the adjacent single-core coated optical fiber optical fiber ribbon, wherein longer than the L _2. Characterized in that the longitudinal length L ₂ of the bonded portion at an arbitrary position, the shortest in substantially the middle of the single-core coated optical fibers between two heart adjacent ones between single-core coated optical fiber wherein the adjacent The optical fiber tape according to claim 1.   The linear member is inserted into a portion where the bonding portion between the two adjacent single-core coated optical fibers is not disposed, and the linear member is moved in the longitudinal direction of the optical fiber tape, and the bonding is performed. The force required to move the linear member when the part is peeled from the single-core-coated optical fiber or the bonded part is broken is 1 N or less. Fiber optic tape. A plurality of optical fiber tapes according to any one of claims 1 to 3 are assembled together by twisting,
An optical fiber cable, wherein the outer circumference of the assembled optical fiber tape is covered with a jacket.   The optical fiber cable according to claim 4, wherein a twist pitch of the optical fiber tape is 500 mm or more. Forming an optical fiber unit in which a plurality of optical fiber tapes according to any one of claims 1 to 3 are twisted together;
A plurality of the optical fiber units are assembled together by twisting,
An optical fiber cable, wherein the outer periphery of the assembled optical fiber unit is covered with a jacket.   The optical fiber cable according to claim 6, wherein a twist pitch of the optical fiber unit is 500 mm or more.   The optical fiber cable according to any one of claims 4 to 7, wherein a twist pitch of the optical fiber tape is 500 mm or more. Assembling a plurality of optical fiber tapes according to any one of claims 1 to 3,
Cover the outer periphery of the assembled optical fiber tape with a jacket,
An optical fiber cable in which two strength members are arranged in the jacket so as to be symmetrical with each other along the length direction with respect to the center of the optical fiber cable,
When the optical fiber cable is bent with a bending radius R, the tensile strain ε applied to the optical fiber is expressed by the following formula (1).
ε ≧ {D + (d / 2)} / R (1)
ε: Tensile strain applied to the optical fiber when the optical fiber cable is bent D: Light mounted at a position farthest away from the plane connecting the centers of the two strength members in the cross section of the optical fiber cable Distance to the center of the fiber (mm)
d: Outer diameter (mm) of single-core coated optical fiber used for optical fiber tape
R: Bending radius applied to optical fiber cable (mm)

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