JP2006258889A - Optical fiber cable - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical fiber cable capable of more easily performing a disassembling operation than the conventional one in the case that a longitudinally attached intermediate layer is employed. <P>SOLUTION: The optical fiber cable is composed of a slot 3 having an optical fiber housing groove 2 on the outer circumferential face, an optical fiber 1 housed in the optical fiber housing groove 2, an intermediate layer 4 covering the slot 3 by being longitudinally attached to the slot 3, a press-wrapping tape 5 spirally wound with spaces apart on the intermediate layer 4, and a sheath 6 covering the slot 3 from above the press-wrapping tape 5, wherein the press-wrapping tape 5 and the sheath 6 are stuck to each other in the structure. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an optical fiber cable, and more particularly to an optical cable having a structure in which an optical fiber is attached to a groove of a slot and covered with a sheath.

  As shown in FIG. 7, for example, the slot type optical fiber cable includes a slot 103 provided with a plurality of grooves 102 in which the optical fiber 101 is accommodated on the outer periphery, a sheath 106 for covering the slot 103, a sheath 106, And an intermediate layer 104 wound between the slots 103. Other structures include a structure in which a presser roll is wound to hold the intermediate layer 104, and a structure in which a second presser roll is wound to hold the optical fiber 101 in the groove 102 of the slot 103.

    The intermediate layer 104 does not transmit heat to the optical fiber 101 when the sheath 106 is extruded and covered, or water that has entered the sheath 106 due to some trouble after the manufacture of the optical fiber cable is finished in the groove 102. In order to prevent running, that is, water running, the entire surface of the slot 103 needs to be covered. In order to prevent water running, the intermediate layer 104 is formed from a material having water absorption.

  As a conventional example that does not use presser winding, as shown in FIG. 8, the tape-shaped intermediate layer 104 is inserted into the slot 103 in a state where the optical fiber 101 is housed in the S twist or Z twist slot 103 in which the groove 102 is twisted in one direction. There is a structure in which the outer peripheral surface is spirally wound and the sheath 106 is further coated thereon. In addition, when winding the intermediate | middle layer 104 helically, it adjusts so that the one part may overlap helically.

  The intermediate layer 104 is not only spirally wound, but also may be wound so that both sides thereof are overlapped along the longitudinal direction of the slot 103 to form a straight line as shown in FIG. . This type of winding is called vertical attachment. In this case, as shown in FIG. 9, a structure in which a thin string-like presser winding 105 is spirally wound to hold the intermediate layer 104 is employed.

  In addition, as shown in FIG. 10, when the SZ twist slot 103 in which the grooves 102 are alternately twisted is used, the second presser winding 107 is spirally wound on the slot 103 to form an optical fiber in the groove 102. The intermediate layer 104 may be spirally wound while holding 101. The second presser winding 107 is wound with a strong tension in order to completely prevent the optical fiber 101 from jumping out of the groove 102. Therefore, high strength is required. In general, a nylon string having a breaking strength of 40 to 100N or a tape made of PET is used as the second presser winding 107, and the winding tension is about 20 to 50N. When the winding tension is weak, a gap is formed between the second presser winding 107 and the slot 103 when the slot 103 is bent, and the optical fiber 101 may be pinched and damaged. The presser roll 105 wound on the intermediate layer 104 does not need to be as strong as the second presser roll 107 theoretically, but the presser roll 105 and the second presser roll 107 have the same or the same structure. In general, it is wound by an attaching device, and selecting a separate material and winding tension for the presser windings 105 and 107 may be very disadvantageous in manufacturing.

Furthermore, as shown in FIG. 11, when the SZ twist slot 103 in which the grooves 102 are alternately twisted is used and the intermediate layer 104 is wound by vertical attachment, a second presser winding 107 is applied around the slot 103, and After winding the intermediate layer 104, the presser winding 105 may be spirally formed on the intermediate layer 104.
Note that the presser foot 105 and the second presser foot 107 may each be formed of a thin tape as well as a string.

  When the intermediate layer 104 is wound vertically, there is a structure in which both sides of the intermediate layer 104 are overlapped with each other via an adhesive, as described in Patent Document 1 below. In this case, the presser winding 105 on the outer periphery can be omitted.

In Patent Document 2, a water-stopping layer made of a water-stopping material in which a water-absorbing resin layer is provided by using a woven fabric or a non-woven fabric as a base on a slot in which an optical fiber core wire is housed in a groove is applied. Further, an optical fiber cable in which a sheath layer (corresponding to an intermediate layer) is coated, wherein the fusion layer prevents the fusion between the water stop layer and the sheath layer between the water stop layer and the sheath layer. An optical cable with a prevention layer interposed is disclosed.
JP 2004-012914 A JP 2002-243999 A

  By the way, the above-described conventional optical fiber cable has the following problems from the viewpoint of disassembly.

  The situation in which the optical fiber cable is disassembled includes the case where the sheath 106 and the presser winding 105 are removed to take out the optical fiber 101 during construction such as branching and connection of the optical transmission system, and the constituent material for recycling the collected cable. There is a case to separate.

  When the sheath 106 is removed during construction such as branching or dismantling of the optical transmission system, the intermediate layer 104 or the presser foot 105 thereon appears below it. In order to remove the wide intermediate layer 104 wound spirally, there is only a method of cutting a part of the intermediate layer 104 and unwinding and removing it from the direction opposite to that at the time of manufacture. Further, when removing the presser foot 105 wound on the longitudinally attached intermediate layer 104, there is a method of cutting the middle part and pulling it off from the main body. If there is, there is a possibility that the portion becomes a resistance, and when the string constituting the presser winding 105 or the narrow tape is pulled, an over tension is applied and the optical fiber 101 in the groove 102 may be damaged.

  In order to avoid this, after all, there is only a method of unscrewing the presser foot 105 in the direction opposite to that at the time of production, and these operations are very heavy and take time. In particular, in the post-intermediate branching work for taking out the optical fiber 101 from the middle of the installed optical fiber cable, the work must be performed in a narrow space, and the work load is large.

  In the case of disassembly separation work, there is no problem even if the optical fiber 101 is damaged. Therefore, when the sheath 106 is removed, a blade such as a cutter is inserted deeply and cut in the longitudinal direction so that the sheath 106 and the presser roll are wound. A method of simultaneously cutting 105 can be employed.

  However, when the wound presser foot 105 is cut in the longitudinal direction, the presser foot 105 becomes a large number of short threads, and a part of the presser foot 105 remains in the sheath 106 and in the groove 102 of the slot 103, and is very separated. It will be difficult.

  As another method, there is a method in which only the sheath 106 is removed, the remaining optical fiber cable is cut into a short length of 1 to 2 m, and then the presser winding 105 is slid along the longitudinal direction of the slot 103 and removed. . However, it is not easy to slide the presser roll 105 wound on the wide tape-shaped intermediate layer 104 and remove it.

  In general, the intermediate layer 104 often has a high coefficient of friction on the surface in consideration of sheath extrudability and the like, and the presser winding may be in a dumpling state due to frictional resistance. Therefore, it takes a lot of work time.

  According to the technique described in Patent Document 1, the intermediate layer 104 is vertically attached, and does not have a spirally wound member on the intermediate layer 104. There is no problem.

  However, both side portions of the vertically attached intermediate layer 104 are bonded via an adhesive, and when removing the intermediate layer 104, there is an operation of cutting the intermediate layer 104 in the longitudinal direction or peeling the bonded portion. Newly occurs, and eventually, there is a limit to the ease of dismantling work.

  Patent Document 2 describes that a fusion prevention layer is provided between a sheath and a water stop layer (corresponding to an intermediate layer). As described in paragraphs 0015 and 0016 of Patent Document 2, the anti-fusing layer is interposed to prevent a direct thermal effect from the sheath to the water-stopping layer. It is intended to prevent the water layer from fusing and a predetermined thickness is required, and covers the entire surface of the water stop layer.

    The fusion prevention layer is made of the same polyethylene as the sheath, and it is disclosed that the fusion prevention layer can be easily peeled off together with the sheath by fusing to the sheath.

  However, in the case of adopting a structure in which the anti-fusing layer is wound by vertical attachment as described in paragraph 0016 of Patent Document 2, how to maintain the longitudinal anti-fusing layer before forming the sheath. There is no description, and there is no description on how to hold down the intermediate layer when the intermediate layer under the anti-fusing layer is vertically attached. Therefore, the conventional technique is adopted for pressing the vertically attached intermediate layer and the anti-fusing layer. However, as described above, the disassembly work cannot be facilitated.

  An object of the present invention is to provide an optical fiber cable that can be disassembled more easily than before when a vertically attached intermediate layer is employed.

  A first aspect of the present invention for solving the above-described problem is that a slot having an optical fiber storage groove on the outer peripheral surface, an optical fiber stored in the optical fiber storage groove, and a vertical attachment to the slot. An intermediate layer covering the slot; a presser wound spirally wound on the intermediate layer; and a sheath that covers the slot from above the presser roll; The sheath is an optical fiber cable having a structure in which the sheath is adhered to each other.

    According to a second aspect of the present invention, in the first aspect, the sheath and the presser foot are made of a thermoplastic material.

    According to a third aspect of the present invention, in the first or second aspect, the sheath and the presser foot are made of the same material.

    According to a fourth aspect of the present invention, in any one of the first to third aspects, the sheath and the presser foot are made of polyethylene.

    According to a fifth aspect of the present invention, in any one of the first to fourth aspects, an adhesive force between the sheath and the presser winding is 0.5 N / mm or more.

    A sixth aspect of the present invention is the sheath according to any one of the first to fifth aspects, wherein the sheath and the presser roll are cut in a state where a part of the sheath is cut without causing a cutter to reach the presser roll. The presser winding also has a structure that breaks when the cutting end is gripped and the sheath is torn in the longitudinal direction.

    According to a seventh aspect of the present invention, in any one of the first to sixth aspects, the presser winding has a tensile breaking strength of 25 N or less.

    According to an eighth aspect of the present invention, in any one of the first to seventh aspects, the second presser winding is spirally wound between the slot and the intermediate layer with an interval between the slot. It further has these.

    According to a ninth aspect of the present invention, in the eighth aspect, an interval between turns of the second presser winding is 5 mm or more on the slot.

    According to a tenth aspect of the present invention, in the eighth or ninth aspect, a static friction coefficient between the slot and the second presser winding is 0.5 or less.

  According to the optical fiber cable of the first aspect, the intermediate layer wound vertically attached to the outer periphery of the slot having the optical fiber housing groove, and the presser winding wound spirally on the intermediate layer at intervals. And a sheath for covering the slot from above the presser winding, and adopting a structure in which the presser winding and the sheath are bonded to each other.

  As a result, when the sheath is removed, the presser winding adhered to the sheath is also removed at the same time, and after removing the sheath, only the longitudinal intermediate layer remains on the cable slot. The work time for removing the presser foot during sorting can be greatly reduced, and work efficiency can be improved.

In the technique of Patent Document 2, when the anti-fusing layer is spirally wound, the anti-fusing layer has a function of pressing the water stop layer, and the anti-fusing layer is fused to the sheath layer. "It is possible to easily peel off the anti-fusing layer together with the sheath layer". However, in order to perform the anti-fusing function, the anti-fusing layer needs to cover the entire surface of the water blocking layer. When the anti-fusing layer is spirally wound, as described in paragraph 0017, the tape width It winds so that it may overlap within the predetermined range. Therefore, the overlapped and wound lower portion cannot be fused with the sheath layer, and is naturally limited to the extent that the fusion prevention layer can be easily peeled off together with the sheath layer. There is. When the sheath layer is torn, if it is torn from one direction, it is torn in the direction from the portion fused to the sheath layer of the anti-fusing layer to the overlapped and unfused portion. When tearing from one direction, it is torn in the direction from the unfused portion to the fused portion. That is, the dismantling workability has a direction dependency, and in the dismantling work, a situation in which attention should be paid to the tearing direction may occur.
On the other hand, in the optical fiber cable according to claim 1, since the presser winding is wound at intervals, there is no portion that cannot be bonded to the sheath except for the manufacturing variation problem. Since the presser roll is excellent in unity, the sheath and the presser roll can be stably and simultaneously removed. Further, since there is no dependency on the sheath tearing direction, the disassembly work can be performed without regard to the direction.

  According to the optical fiber cable of the second aspect, since the sheath and the presser winding are made of a thermoplastic material, the sheath material heated and melted is a general sheath coating method when the sheath material is extruded and coated. The heat of the sheath causes the presser winding to be in a molten or semi-molten state, and the sheath and the presser winding can be bonded without providing a special process.

  When the presser wound wound spirally is the same material as the sheath as in the optical fiber cable according to claim 3, a recycled material having high purity without separating the presser wound from the sheath removed by disassembly Can be used as

  If the sheath and the presser winding are made of polyethylene as in the optical fiber cable according to the fourth aspect, stable characteristics as the sheath can be obtained.

  As in the case of the optical fiber cable according to claim 5, if the adhesive force between the sheath and the presser roll is 0.5 N / mm or more, the sheath and the presser roll are not separated during the dismantling operation, and the simultaneous removal of the sheath and the presser roll is stabilized Can be done.

When disassembling an optical fiber cable for branching work or the like, it is not desirable to damage the optical fiber. Therefore, when inserting the cutter from the outside of the sheath, it is desired that the cutter does not reach the presser winding.

As in the case of the optical fiber cable according to claim 6, when the sheath cutting end is grasped and the sheath is torn in the longitudinal direction in a state where a part of the sheath is cut without reaching the blade to the presser winding, the presser roll is also broken. If comprised in this way, the simultaneous removal of a sheath and a presser foot can be easily performed without inserting a blade deeply.

As in the case of the optical fiber cable according to the seventh aspect, if the tensile breaking strength of the presser winding is 25 N or less, simple disassembly workability can be achieved.
If the presser foot strength is set low, it will be disadvantageous that it will break easily during manufacturing. However, the present invention goes beyond the manufacturing benefits / disadvantages and takes the long-term view of global environmental conservation into consideration. As a result of diligent research, we have come up with a view from a different viewpoint, such as recyclability and recyclability. Note that the presser winding may have a reduced tensile breaking strength due to the influence of heat or the like when covering the sheath. In such a case, it is possible to employ a value that is low enough to withstand the presser winding process as the tensile rupture strength of the presser roll after being formed into an optical fiber cable.

  According to the optical fiber cable of the first to seventh aspects, the presser winding is also removed simultaneously with the removal of the sheath, and the intermediate layer appears. Since the intermediate layer is wound vertically, the intermediate layer opens at the same time as the sheath is removed. This is advantageous from the viewpoint of disassembly, but in the case of SZ twisting in particular, when the intermediate layer is opened, the optical fiber housed in the optical fiber housing groove will jump out. In order to prevent this, there is an advantage that the second presser winding is provided under the intermediate layer as in the optical fiber cable according to the eighth aspect. In addition, the second presser winding holds the optical fiber until the intermediate layer is applied at the time of manufacture, which contributes to stabilization of the manufacture. Although it is somewhat complicated to remove the spirally wound second presser winding, if the spirally wound at intervals like the optical fiber cable according to claim 8, the second presser winding Since the contact area of the slot is small, there is little friction, and it is easy to remove the second presser roll by shifting it sideways. In general, since the surface of the slot is smooth and has a low coefficient of friction, the work of removing the second presser wound wound on the slot by moving it sideways is wound on an intermediate layer having a high coefficient of friction. There is less problem than the work of shifting the presser foot to the side and removing it, and a sufficiently easy workability can be ensured by spirally winding with a gap. Further, when the second presser winding is cut and removed, since the blade can be used while visually observing the optical fiber so as not to be damaged from the gap between the spiral windings, the possibility of damaging the optical fiber is reduced.

  As in the case of the optical fiber cable according to the ninth aspect, when the interval width is set to 5 mm or more, it is possible to use the blade while visually checking.

  If the coefficient of static friction between the slot and the second presser winding is 0.5 or less as in the case of the optical fiber cable according to the tenth aspect, the work of removing the second presser roll by shifting it sideways can be easily performed. .

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
(First embodiment)
FIG. 1 is a cross-sectional view showing an optical fiber cable according to the first embodiment of the present invention, and FIG. 2A shows a state in which a part of the optical fiber cable before forming a sheath is cut out. A side view and the figure (b) are side views showing the state where a part of the optical fiber cable after forming the sheath was cut out.

  In FIG. 2A, a non-woven fabric having a width of 40 mm and a thickness of 0.3 mm is placed on an SZ twist slot 3 having an outer diameter of 9.0 mm formed by alternately twisting grooves 2 for accommodating the optical fiber cores 1. An intermediate layer 4 made of On the intermediate layer 4, three presser windings 5 made of polyethylene tape having a width of 2.5 mm and a thickness of 0.05 are spirally wound at equal intervals. In this case, both side portions of the intermediate layer 4 are pressed against the slot 3 by the presser winding 5 in a state where they are overlapped without using an adhesive. The presser winding may be a narrow tape or a string.

  In this state, as shown in FIGS. 1 and 2B, a sheath 6 made of polyethylene is coated on the presser winding 5 and the intermediate layer 4 by extrusion coating so as to have a thickness of 2.0 mm. The extrusion temperature of the sheath 6 is 190 ° C., which is higher than the presser winding 5 made of polyethylene tape having a melting point of 140 ° C. Therefore, the presser winding 5 after the sheath 6 is pushed out is joined and integrated with the sheath 6.

  In the optical fiber cable having the above configuration, the presser winding 5 is wound on the intermediate layer 4 wound by vertical attachment, and the presser winding 5 is bonded to the inside of the sheath 6 after the sheath 6 is formed.

  Therefore, although there is a process of winding the presser winding 5 in the manufacture of the optical fiber cable, once the presser winding 5 is completed, the presser winding 5 is bonded to the inner side of the sheath 6, so It is as if only the sheath 6 exists. In addition, the presser foot 5 does not need to cover the entire surface as long as the lower layer state can be maintained, and it is easier to secure the integrity with the sheath 6 when wound at intervals, and the weight of the cable can be reduced. The amount of consumption can be reduced and the winding time can be shortened.

以上の結果から、０．５Ｎ／ｍｍ以上の接着力を有する場合に解体作業性が優れることがわかる。 Table 1 shows the relationship between the adhesive force between the presser winding 5 and the sheath 6 and the dismantling workability of such an optical fiber cable. The results in Table 1 show that when the cutter is put in the sheath 6 and the presser winding 5, the presser winding 5 is cut in advance and the sheath 6 is removed, the sheath 6 and the presser winding 5 are integrally removed from the slot 3. ◯ indicates that the integrity is maintained, and × indicates that the integrity is not maintained, and the presser winding 5 has been separated from the sheath 6.

From the above results, it can be seen that the dismantling workability is excellent when the adhesive strength is 0.5 N / mm or more.

  In particular, if the sheath 6 and the presser foot 5 are the same substance, they can be easily integrated when the sheath 6 is formed. Therefore, the sheath 6 and the presser foot 5 can be disassembled as a single body and separated as a single material, which is advantageous for recycling. It is.

  By the way, when the optical fiber cable is disassembled for a branching operation or the like, if it is not desired to damage the optical fiber 1, it is preferable that the blade inserted from the outside of the sheath 6 has a depth that does not reach the presser winding 5. Then, if a part of the sheath 6 is cut along the longitudinal direction, the cutting end is gripped and the sheath 6 is torn in the longitudinal direction, the blade is put into the thin presser winding 5 adhered to the inside of the sheath 6. Even if not, it is preferable that the sheath 6 can be disassembled together with the presser foot 5. Since the intermediate layer 4 that appears after removing the sheath 6 and the presser winding 5 is a longitudinally attached winding and is not bonded, it can be easily opened by removing the sheath 6 and the presser winding 5, which is advantageous in terms of disassembly.

    In this case, if the adhesive force between the sheath 6 and the presser winding 5 is weak, the presser winding 5 is separated from the sheath 6 when the sheath 6 is torn, making it difficult to tear together with the sheath 6. If the strength is too strong, it will be difficult to tear. In addition, in the case where the blade is inserted only halfway through the thickness of the sheath 6, if the strength of the sheath 6 is too high, the presser foot 5 is difficult to be torn.

Table 2 shows the examples of the sheath 6 with respect to Examples and Comparative Examples in which the strength, thickness, width, cross-sectional area, presser winding interval of the presser foot 5, the thickness of the sheath 6, and the presser winding / sheath bonding strength are different. It shows the result of investigating whether the sheath 6 and the presser winding 5 were broken while maintaining the integrated state after the sheath 6 was torn from the cut after cutting the blade halfway along the longitudinal direction.

  In Table 2, Examples 4 to 6 maintained the integrated state with the presser winding 5 when the sheath 6 was torn, and the presser winding 5 was also broken, and good results were obtained. In Examples 7 and 8, the presser winding 5 was also broken when the sheath 6 was torn, but the integrated state of the sheath 6 and the presser winding 5 could not be maintained. Furthermore, in Comparative Example 3, the presser winding 5 remained on the intermediate layer 4 without breaking, and only the sheath 6 was broken and removed. In Comparative Example 4, the strength of the presser foot was too strong, and the manual tearing operation was not possible.

  That is, in Examples 4 to 8, the sheath 6 and the presser winding 5 hold the cutting end of the sheath 6 in a state in which a part of the sheath 6 is cut without causing the cutter to reach the presser winding 5, and the sheath 6 In the fourth to sixth embodiments, the integrity of the sheath 6 and the presser roll 5 is maintained even when the presser roll 5 is torn together with the sheath 6. It is more preferable.

  Moreover, it is preferable that the breaking strength of the presser winding 5 is 25 N or less. If it is larger than 25N, it will take time and labor since it cannot be torn with bare hands when dismantling.

  By the way, the optical fiber to be inserted into the groove 2 provided in the slot 3 is not limited to the optical fiber tape 1 as shown in FIG. 1, and the optical fiber single wire 1a can be accommodated as shown in FIG. Or as shown in FIG.3 (b), the structure which accommodates the optical fiber single wire 1b bundled in multiple numbers may be sufficient. Further, as a slot for storing the optical fiber tape 1, the optical fiber single wires 1a, 1b, etc., an S twist slot 3a in which a groove 2a for storing an optical fiber as shown in FIG. 4 is twisted in one side may be used.

  Further, the material of the vertically attached intermediate layer 4 is not limited to the nonwoven fabric coated with water-absorbing powder, and may be made of a general plastic.

(Second Embodiment)
FIG. 5A is a side view showing a state in which a portion of the optical fiber cable according to the second embodiment of the present invention is cut out before forming the sheath, and FIG. 5B shows the optical fiber. It is a side view which shows the state which notched a part after forming the sheath of a cable. 5A and 5B, the same reference numerals as those in FIGS. 1 and 2 indicate the same elements.

  In FIG. 5A, on the SZ twist slot 3 having an outer diameter of 9.0 mm formed by alternately twisting the grooves 2 for accommodating the optical fiber cores 1, A narrow tape is spirally wound at intervals, thereby preventing the optical fiber 1 in the groove 2 from jumping out of the slot 3.

  An intermediate layer 4 made of the same non-woven fabric as in the first embodiment is wound on the second presser winding 7 and the slot 3 with vertical attachment. Further, on the intermediate layer 4, three presser windings 5 made of polyethylene tape are spirally wound at equal intervals as in the first embodiment, and are held down by the slots 3.

  In this state, as shown in FIG. 5B, a sheath 6 made of polyethylene is coated on the presser winding 5 and the intermediate layer 4 by extrusion coating so as to have a thickness of 2.0 mm. The extrusion temperature of the sheath 6 is higher than the presser winding 5 made of polyethylene tape, and the presser winding 5 after the sheath 6 is pushed out is joined and integrated with the sheath 6.

  In the SZ twist slot 3, the optical fiber 1 in the groove 2 is easily popped out at the same time as the intermediate layer 4 is opened, but the popping out is prevented by the second presser winding 7. Further, the second presser winding 7 holds the optical fiber 1 until the intermediate layer 4 is applied at the time of manufacturing the optical fiber cable, which contributes to stabilization of manufacturing.

  It should be noted that disassembling the second presser winding 7 wound in a spiral is somewhat complicated, but the second presser winding 7 is such that there is a gap between the second presser winding 7 and the slot 3. If the contact area between the slot 3 and the slot 3 is reduced, the friction between the second presser roll 7 and the slot 3 is reduced, and the second presser roll 7 is moved along the longitudinal direction of the slot 3 and removed. Easy. That is, the frictional force of the presser winding 5 on the intermediate layer 4 is larger than the frictional force of the second presser winding 7 on the slot 3. If the frictional force between the second presser winding 7 and the slot 3 is expressed by a static friction coefficient, it is preferably 0.5 or less.

  The intermediate layer 4 has a large surface roughness in order to provide heat shielding and water absorption functions, but since the slot 3 is formed by resin extrusion, the surface roughness is small and slippery. Further, when the second presser winding 7 is cut and removed, the cutting tool can be used while visually observing the optical fiber 1 from the gap of the second presser winding 7, so that the optical fiber 1 is damaged. The possibility of decreases. In order to effectively use the blade while visually observing, the interval W between the second presser windings 7 on the slot 3 is preferably set to 5 mm or more.

Next, the width, thickness, winding tension, presser winding interval, slot / second presser winding static friction coefficient of the second presser winding 7 are shown for Examples 9 and 10 and Comparative Example 5, and Table 3 shows the result of confirming whether the second presser winding 7 was shifted by 2 m along the longitudinal direction of the slot with a bare hand.

(Other embodiments)
Although it is preferable to use the same material as that of the sheath 6 as the material of the presser winding 5 wound on the intermediate layer 4 that is wound vertically, the present invention is not limited to this.

    For example, when the sheath 6 and the presser foot 5 are made of a thermoplastic material and the material of the presser foot 5 is formed of a plastic material having a melting point lower than the extrusion temperature of the sheath 6, the presser foot 5 is formed when the sheath 6 is formed by heating and melting. It becomes possible to adhere the winding 5 to the inside of the sheath 6.

  Moreover, as shown in FIG. 6, you may employ | adopt the structure which formed the presser foot 5 with the plastic 5a, and apply | coated the adhesive agent 5b fuse | melted on sheath extrusion temperature on it. In this case, it is possible to bond the adhesive 5b to the inside of the sheath 6 by forming the sheath 6 by heating and melting after the presser winding 5 is wound around the intermediate layer 4 with the adhesive 5b facing outward. Become. In this case, for example, nylon or PET may be used as a material for the plastic 5a constituting the presser winding 5.

FIG. 1 is a sectional view showing an optical fiber cable according to the first embodiment of the present invention. FIG. 2A is a side view showing a state in which a portion of the optical fiber cable according to the first embodiment of the present invention is not cut before the sheath is formed, and FIG. 2B is the optical fiber. It is a side view which shows the state which notched a part after forming the sheath of a cable. 3A and 3B are cross-sectional views showing other examples of the optical fiber cable according to the first embodiment of the present invention. FIG. 4 is a side view showing another example of the slots constituting the optical fiber cable according to the first embodiment of the present invention. FIG. 5A is a side view showing a state in which a part of a state before forming a sheath is cut out in the optical fiber cable according to the second embodiment of the present invention, and FIG. It is a side view which shows the state which notched a part after forming the sheath of a cable. FIG. 6 is a cross-sectional view showing another example of a presser winding constituting an optical fiber cable according to another embodiment of the present invention. FIG. 7 is a cross-sectional view showing a conventional optical fiber cable. FIG. 8 is a side view showing a first optical fiber cable according to the prior art. FIG. 9 is a side view showing a second optical fiber cable according to the prior art. FIG. 10 is a side view showing a third optical fiber cable according to the prior art. FIG. 11 is a side view showing a fourth optical fiber cable according to the prior art.

Explanation of symbols

1: Optical fiber core wire 2: Groove 3: Slot 4: Intermediate layer 5, 7: Presser winding 6: Sheath

Claims (10)

A slot having an optical fiber housing groove on the outer peripheral surface;
An optical fiber housed in the optical fiber housing groove;
An intermediate layer vertically attached to the slot and covering the slot;
A presser wound spirally wound around the intermediate layer at an interval;
A sheath for covering the slot from above the presser winding,
An optical fiber cable having a structure in which the presser winding and the sheath are bonded to each other. The optical fiber cable according to claim 1, wherein the sheath and the presser winding are made of a thermoplastic material. The optical fiber cable according to claim 1 or 2, wherein the sheath and the presser winding are made of the same material. The optical fiber cable according to any one of claims 1 to 3, wherein the sheath and the presser winding are made of polyethylene. The optical fiber cable according to any one of claims 1 to 4, wherein an adhesive force between the sheath and the presser winding is 0.5 N / mm or more. When the sheath and the presser roll are torn in the longitudinal direction by grasping the cut end of the sheath in a state in which a part of the sheath is cut without causing a cutter to reach the presser roll, the presser roll is also 6. The optical fiber cable according to claim 1, wherein the optical fiber cable has a structure that breaks. The optical fiber cable according to any one of claims 1 to 6, wherein the presser winding has a tensile breaking strength of 25N or less. 8. The apparatus further comprises a second presser winding wound spirally between the slot and the intermediate layer so as to be spaced apart from the slot. 9. The optical fiber cable described. The optical fiber cable according to claim 8, wherein an interval between windings of the second presser winding is 5 mm or more on the slot. The optical fiber cable according to claim 8 or 9, wherein a static friction coefficient between the slot and the second presser winding is 0.5 or less.

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