Intermittently adhesive optical fiber ribbon, optical fiber cable

Abstract

To provide an intermittently adhering optical fiber ribbon and the like with which, even when mounted to an optical fiber cable with high density, it is possible to suppress an increase in transmission loss.SOLUTION: An intermittently adhering optical fiber ribbon 10 is composed of a plurality of optical fiber ribbons 3 that are bonded in parallel. The optical fiber ribbons 3 adjacent to each other are bonded at a prescribed interval in the longitudinal direction of the intermittently adhering optical fiber ribbon 10 by adhesive parts 21 which are intermittently arranged. In a cross section perpendicular to the longitudinal direction of the optical fiber ribbons at the position of any adhesive part 21, the average angle in an array direction of optical fiber ribbons (connecting body 17) bonded by the adhesive part 21, with respect to a parallel direction D of the optical fiber ribbons 3, is 1 degree to 20 degrees inclusive.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an intermittently bonded optical fiber ribbon in which a plurality of optical fibers are arranged in parallel and intermittently bonded in the longitudinal direction. [Background technology]

[0002] As an optical fiber for transmitting a large amount of data at high speed, an optical fiber ribbon is used in which a plurality of optical fiber core wires are arranged in parallel and adjacent optical fiber core wires are bonded together to simplify storage in a cable and work. As an optical fiber ribbon, there is used an optical fiber ribbon in which parallel optical fiber core wires are fixed over the entire length with resin, and there is also an optical fiber ribbon in which optical fiber core wires are bonded together intermittently in the longitudinal direction (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-027200 Summary of the Invention [Problem to be solved by the invention]

[0004] When an intermittently adhesive optical fiber ribbon such as that described in Patent Document 1 is installed in an optical fiber cable, the optical fibers can move freely in a single-core state at the unconnected portions, so that no significant strain is applied to the optical fibers when the optical fiber cable is bent. In this way, intermittent adhesion between optical fiber fibers has the advantages of reducing transmission loss due to bending and making it easier to convert to a single-core configuration.

[0005] However, the inventors have found that simply mounting intermittently adhesive optical fiber ribbons in an optical fiber cable at high density inhibits the movement of the optical fibers within the cable core, which leads to an increase in transmission loss. Therefore, there is a demand for an optical fiber ribbon that can inhibit an increase in transmission loss even when mounted at higher density.

[0006] The present invention has been made in consideration of such problems, and aims to provide an intermittently adhesive type optical fiber ribbon or the like that can suppress an increase in transmission loss even when densely mounted in an optical fiber cable. [Means for solving the problem]

[0007] In order to achieve the above-mentioned object, the first invention is , complex This intermittently bonded optical fiber ribbon has several optical fiber core wires arranged in parallel, and adjacent optical fiber core wires are intermittently bonded together at adhesive joints formed at predetermined intervals in the longitudinal direction of the optical fiber ribbon, and adjacent adhesive joints in the parallel direction of the optical fiber core wires are positioned at positions shifted from the longitudinal direction of the optical fiber ribbon, and in a cross section perpendicular to the longitudinal direction of the optical fiber ribbon at the position of any of the adhesive joints, the same cross section has multiple adhesive joints, and when no external force is applied to the optical fiber ribbon, the average angle, which is the average value of the angle of the arrangement direction of multiple optical fiber core wires respectively bonded at multiple adhesive joints located in the same cross section with respect to the parallel direction of the optical fiber core wires, is between 1 degree and 20 degrees, and the lengths between the adhesive joints in the longitudinal direction of adjacent optical fiber core wires are different, and the difference in length between the adhesive joints of the adjacent optical fiber core wires changes in the longitudinal direction.

[0008] The optical fiber core wire may be a two-core optical fiber ribbon core wire in which two optical fiber strands are connected in the longitudinal direction, and adjacent two-core optical fiber ribbon core wires may be intermittently bonded at the bonding portions formed at predetermined intervals in the longitudinal direction of the optical fiber ribbon core wire.

[0009] In a cross section perpendicular to the longitudinal direction of the optical fiber ribbon at the position of any of the adhesive joints, the average angle of the arrangement direction of the optical fiber core wires bonded at the adhesive joint relative to the parallel direction of the optical fiber core wires may be greater than or equal to 1 degree and less than or equal to 10 degrees.

[0010] No. 1 of According to the invention, adjacent optical fiber cores are arranged at a predetermined angle at the adhesive joint relative to the parallel direction of the optical fiber cores, so there is little restriction on the movement of the optical fiber cores, and even when they are densely packed into an optical fiber cable, an increase in transmission loss can be suppressed.

[0011] For example, in the case of a conventional intermittently adhesive optical fiber ribbon in which the optical fibers are arranged in a straight line in a parallel direction, although the optical fibers can move freely in the non-adhesive portions, the direction in which they can move is actually limited because they are sandwiched between adjacent optical fibers. In contrast, if adjacent optical fibers are arranged at an angle to the parallel direction of the optical fibers, the number of directions in which each optical fiber can move increases, increasing the degree of freedom, allowing the optical fibers to move more efficiently and suppressing an increase in transmission loss.

[0012] Each optical fiber core wire constituting the intermittently bonded optical fiber ribbon may be a single core, or may be a two-core optical fiber ribbon in which two optical fibers are connected in the longitudinal direction. The two-core optical fiber ribbon may be bonded over its entire length.

[0013] No. 2 The invention is 1 ofThe optical fiber cable uses an intermittently bonded optical fiber ribbon core wire according to the present invention, characterized in that it comprises: a cable core formed by twisting together a plurality of the intermittently bonded optical fiber ribbon core wires to form an optical fiber unit; a core portion formed by twisting together a plurality of the optical fiber units; and a pressure winding member longitudinally wound around the outer periphery of the core portion; a tension member arranged outside the cable core; and an outer sheath covering the cable core and the tension member.

[0014] No. 2 According to the present invention, an optical fiber cable capable of suppressing an increase in transmission loss can be obtained. [Effects of the Invention]

[0015] According to the present invention, it is possible to provide an intermittently bonded optical fiber ribbon or the like that can suppress an increase in transmission loss even when densely mounted in an optical fiber cable. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a cross-sectional view showing an optical fiber cable 1. FIG. [Figure 2] 1 is a perspective view showing an intermittently adhesive type optical fiber ribbon 10. FIG. [Figure 3] 2. (a) is a cross-sectional view taken along line AA in FIG. 2, (b) is a cross-sectional view taken along line BB in FIG. 2, and (c) is a cross-sectional view taken along line CC in FIG. [Figure 4] FIG. 2 is a diagram showing a ribbon optical fiber manufacturing apparatus 30. [Figure 5] 1(a) to 1(c) are cross-sectional views of an intermittently bonded optical fiber ribbon 10a. [Figure 6] FIG. 10 is a cross-sectional view of another embodiment of the intermittently bonded optical fiber ribbon 10a. DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a cross-sectional view of an optical fiber cable 1. The optical fiber cable 1 is a slotless cable that does not use a slot, and is composed of a cable core 15, a tension member 9, an outer jacket 13, etc.

[0018] The cable core 15 has a substantially circular outer shape and includes a core portion 4 made up of a plurality of intermittently bonded optical fiber ribbons 10, and a holding winding member 7 wound around the outer periphery of the core portion 4. The core portion 4 is formed by twisting together a plurality of optical fiber units 5. The optical fiber unit 5 is also formed by twisting together a plurality of intermittently bonded optical fiber ribbons 10. The intermittently bonded optical fiber ribbons 10 will be described in detail later.

[0019] As described above, the pressure winding member 7 is wound around the outer periphery of the core portion 4. The pressure winding member 7 is a tape-like member, a nonwoven fabric, or the like, and is arranged, for example, by longitudinal wrapping to collectively cover the outer periphery of the core portion 4. That is, the pressure winding member 7 is longitudinally wrapped around the outer periphery of the plurality of optical fiber units 5 so that the longitudinal direction of the pressure winding member 7 substantially coincides with the axial direction of the optical fiber cable 1 and the width direction of the pressure winding member 7 is the circumferential direction of the optical fiber cable 1. Note that a pressure winding string or the like (not shown) is wound around the outer periphery of the pressure winding member 7 to prevent the opening of the pressure winding member 7, for example.

[0020] In a cross section perpendicular to the longitudinal direction of the cable core 15, tension members 9 are provided on both sides of the exterior of the cable core 15. That is, a pair of tension members 9 are provided at positions facing each other with the cable core 15 in between. In addition, tear cords 11 are provided in a direction approximately perpendicular to the facing direction of the tension members 9 so as to face each other with the cable core 15 in between.

[0021] An outer sheath 13 is provided on the outer periphery of the cable core 15. The tension members 9 and tear cords 11 are embedded in the outer sheath 13. In other words, the outer sheath 13 is provided so as to cover the cable core 15, the tension members 9, etc. The outer shape of the outer sheath 13 is approximately circular. The outer sheath 13 is made of, for example, a polyolefin-based resin. Note that the arrangement and number of the tension members 9 and tear cords 11 are not limited to the example shown in the figure.

[0022] Next, we will explain the intermittently bonded optical fiber ribbon 10. Fig. 2 is a perspective view of the intermittently bonded optical fiber ribbon 10, Fig. 3(a) is a cross-sectional view taken along line AA in Fig. 2, Fig. 3(b) is a cross-sectional view taken along line BB in Fig. 2, and Fig. 3(c) is a cross-sectional view taken along line CC in Fig. 2.

[0023] The intermittently bonded optical fiber ribbon 10 is configured by bonding a plurality of optical fiber core wires 3 in parallel. In this embodiment, the intermittently bonded optical fiber ribbon 10 is configured by a single-core optical fiber core wire 3 (a single-core optical fiber core wire may be called an optical fiber bare wire). The optical fiber core wire 3 is, for example, a bare optical fiber with an outer diameter of 0.125 mm, with a coating layer and a coloring layer applied to the outer circumference thereof to give an outer diameter of 0.2 mm.

[0024] In this embodiment, an example is shown in which the intermittently bonded optical fiber ribbon 10 is composed of 16 optical fiber core wires 3, but the present invention is not limited to this, and the number of optical fiber core wires 3 is not particularly limited as long as the intermittently bonded optical fiber ribbon has three or more optical fiber core wires 3 arranged in parallel.

[0025] Adjacent optical fibers 3 are bonded together by adhesive parts 21 that are intermittently arranged at predetermined intervals in the longitudinal direction of the intermittently bonded optical fiber ribbon 10. Adjacent adhesive parts 21 in the juxtaposition direction of the optical fibers 3 are arranged at positions offset from each other in the longitudinal direction of the intermittently bonded optical fiber ribbon 10.

[0026] That is, the bonding parts 21 located at odd numbers from one end in the parallel direction of the optical fibers 3 are positioned at approximately the same positions in the longitudinal direction of the intermittently bonded optical fiber ribbon 10. Similarly, the bonding parts 21 located at even numbers from one end in the parallel direction of the optical fibers 3 are positioned at approximately the same positions in the longitudinal direction of the intermittently bonded optical fiber ribbon 10. Furthermore, the odd-numbered bonding positions (bonding parts 21) and the even-numbered bonding positions (bonding parts 21) are shifted by approximately half a pitch in the longitudinal direction and are arranged, for example, in a staggered pattern.

[0027] The adhesive portions 21 of adjacent optical fibers 3 in the longitudinal direction of the intermittently adhesive type optical fiber ribbon 10 are all formed at approximately the same pitch.

[0028] 3(a) to 3(c), in a cross section perpendicular to the longitudinal direction of the optical fiber ribbon at the position of any one of the bonding portions 21, the arrangement direction (straight line E in FIG. 3(a)) of the optical fibers bonded at the bonding portions 21 is inclined with respect to the parallel direction of the optical fibers 3 (straight line D in FIG. 3(a)). In other words, the optical fibers 3 are not aligned straight in the parallel direction, but are arranged at a position that is inclined and shifted from the straight line in the parallel direction, and unevenness caused by the misalignment of the optical fibers 3 is formed on the top and bottom surfaces of the optical fiber ribbon.

[0029] Hereinafter, a pair of optical fibers 3 bonded at the bonding portion 21 in the cross section at the bonding portion 21 will be simply referred to as a coupled body 17. In this case, the parallel direction D of the optical fibers 3 substantially coincides with a straight line approximating the parallel direction (straight line D) of the coupled body 17. The tilt angle of each coupled body 17 (arrangement direction of the optical fibers) from the parallel direction (straight line D) is defined as an acute angle, such as the angles θ1 and θ2 formed by D and the lines E1 and E2 in FIG. 3(a). In other words, the tilt angle from the parallel direction D is defined for each coupled body 17 in the range of 0 degrees to 90 degrees.

[0030] The inclination angle of each of the connected bodies 17 at the bonding portion 21 is not constant. Furthermore, the inclination angle of each of the connected bodies 17 at the bonding portion 21 in the longitudinal direction of the intermittently bonded optical fiber ribbon 10 is not constant. That is, the inclination angle of each of the connected bodies 17 from the parallel direction D is different at the position of each bonding portion 21.

[0031] Here, the tilt angle from the parallel direction D is measured for each of the linked bodies 17 at the position of any given bonding portion 21, and the average is taken as the average angle of the arrangement direction of the linked bodies 17 (the optical fibers bonded at the bonding portion 21) at that bonding portion 21. In this case, the average angle of the arrangement direction of the linked bodies 17 at the bonding portion 21 is preferably 1 degree or more and 20 degrees or less, and more preferably 1 degree or more and 10 degrees or less. That is, in a cross section perpendicular to the longitudinal direction of the optical fiber ribbon at the position of any bonding portion 21, the average angle of the arrangement direction of the optical fibers (linked bodies 17) bonded at the bonding portion 21 with respect to the parallel direction D of the optical fibers 3 is preferably 1 degree or more and 20 degrees or less, and more preferably 1 degree or more and 10 degrees or less.

[0032] If the average angle of the arrangement direction of the connected bodies 17 is less than 1 degree, the effect of the present invention is small. On the other hand, if the average angle of the arrangement direction of the connected bodies 17 exceeds 20 degrees, the workability of setting the optical fiber ribbon in the fusion splicer during the fusion work deteriorates.

[0033] Typically, when fusion splicing an optical fiber ribbon, the optical fiber ribbon is set in a holder, the holder is set in a fusion splicer, and the tips of the optical fibers protruding from the tip of the holder are placed in V-grooves formed in the holding section of the fusion splicer. If the tilt angle is too large, the optical fibers exposed from the holder tend to move around, making it difficult to place them in the V-grooves. For this reason, the average angle of the arrangement direction of the connected body 17 is preferably 20 degrees or less, and more preferably 10 degrees or less.

[0034] Next, a method for manufacturing an intermittently bonded optical fiber ribbon 10 for splicing adjacent optical fibers together will be described. Fig. 4 is a diagram showing a schematic configuration of a ribbon ribbon manufacturing apparatus 30. Note that the number of optical fibers in the intermittently bonded optical fiber ribbon 10 is not particularly limited as long as three or more optical fibers are arranged in parallel, but in the illustrated example, a case will be described in which 12 optical fibers are integrated into a ribbon to manufacture the intermittently bonded optical fiber ribbon 10.

[0035] The ribbon fiber manufacturing apparatus 30 mainly comprises a supply drum 31, a resin applicator 37, a curing device 39, a tension detector 41, a take-up device 43, and a take-up drum 45. The optical fiber core wires 3 are individually fed out from each of the 12 supply drums 31 and arranged in parallel in the resin applicator 37.

[0036] The resin applicator 37 is composed of a die 33 that maintains the traveling optical fiber core wires 3 in a parallel state, and a resin supply control unit 35 that controls the amount and timing of discharging adhesive (connecting resin) when it is discharged from a discharge port formed in the die 33. In the resin applicator 37, each optical fiber core wire 3 fed from the supply drum 31 is inserted into the die 33, and adhesive is intermittently applied between adjacent optical fiber core wires at predetermined intervals in the longitudinal direction.

[0037] The optical fiber cores 3 coated with adhesive by the resin coating device 37 are passed in parallel and closely spaced relation to each other through the curing device 39. In the curing device 39, the adhesive coated on the optical fiber cores 3 is cured by, for example, ultraviolet light irradiation or heat.

[0038] The tension detector 41 is a sensor that measures the tension of the intermittently bonded optical fiber ribbon 10. Based on the measurement results of this tension detector 41, a predetermined tension can be applied to the optical fiber 3, for example, by controlling the payout speed (brake) of each optical fiber 3 on the supply drum 31.

[0039] The rotation speed of the take-up device 43 (capstan roller) is controlled by a control device. The running speed of the intermittently bonded optical fiber ribbon 10 is adjusted by the rotation speed of the take-up device 43. The rotation speed of the take-up device 43 is input to the resin supply control unit 35 of the resin applicator 37 as a signal (running speed signal) indicating the running speed of the intermittently bonded optical fiber ribbon 10.

[0040] The intermittently bonded optical fiber ribbon 10 is taken up at a predetermined line speed by the take-up device 43 and wound up on the winding drum 45. In this manner, the intermittently bonded optical fiber ribbon 10 is manufactured.

[0041] Furthermore, a cable core 15 is formed using a plurality of intermittently bonded optical fiber ribbon cores 10 obtained in this manner, and an optical fiber cable 1 can be obtained by arranging a tension member 9 or the like around the outer periphery of the cable core 15 and covering it with an outer jacket 13.

[0042] As described above, a predetermined tension is applied to each optical fiber from the optical fiber supply section to the optical fiber ribbon winding section of the ribbon fiber manufacturing apparatus 30. At this time, by adjusting the payout speed (brake) so that a different tension is applied to each supply drum 31, the tension of each optical fiber 3 can be changed individually.

[0043] For example, taking adjacent optical fiber core wires 3, the tension of one optical fiber core wire 3 is set to be greater than the tension of the other optical fiber core wire 3. When tension is applied, the optical fiber strand stretches slightly in response to the tension, so when the adhesive is applied, cured, and then the tension is released, the optical fiber core wire 3 with the relatively low tension becomes slightly longer than the optical fiber core wire 3 with the relatively high tension.

[0044] If this tension difference is constant in the longitudinal direction, the same optical fiber will always be relatively long, resulting in slack between the bonded portions 21, for example. On the other hand, if this tension difference is varied in the longitudinal direction, for example, one optical fiber will be longer than the other in one portion of the longitudinal direction, and one optical fiber will be shorter than the other in another portion of the longitudinal direction. In this way, the optical fiber 3 (connected body 17) will rotate in an attempt to absorb the difference in length between the bonded portions 21. As a result, the connected body 17 can be made to tilt with respect to the parallel direction D at each bonded portion 21.

[0045] For example, by alternately arranging optical fiber core wires with relatively high tension and optical fiber core wires with relatively low tension in the parallel direction of the optical fiber core wires 3 and periodically switching the relative magnitude of this tension in the longitudinal direction, it is possible to obtain an intermittently bonded optical fiber ribbon 10 in which the linked bodies 17 are tilted with respect to the parallel direction D at all bonding joints 21. Furthermore, since the greater the tension difference, the larger the rotation angle, it is also possible to adjust the average tilt angle of the linked bodies 17 by adjusting the tension difference. Note that the manufacturing method is not limited to the above-mentioned method as long as it is possible to tilt the arrangement direction of adjacent optical fiber core wires (linked bodies 17).

[0046] As described above, according to this embodiment, in a cross section perpendicular to the longitudinal direction of the optical fiber ribbon at the position of any one of the bonding portions 21, the arrangement direction of the optical fibers bonded at the bonding portions 21 (connected bodies 17) is inclined with respect to the parallel direction of the optical fibers 3. Therefore, when the intermittently bonded optical fiber ribbon 10 is bent, the optical fibers 3 are more likely to move in any direction compared to when they are arranged in a straight line. Therefore, even when the optical fiber ribbon 1 is densely packed, an increase in transmission loss can be suppressed.

[0047] Furthermore, by setting the average angle of the arrangement direction of the connected bodies 17 in the adhesive portion 21 to a predetermined value or less, it is easy to arrange the optical fibers in the respective V-grooves when setting them in the fusion splicer.

[0048] In the above-described embodiment, the intermittently bonded optical fiber ribbon 10 is configured with the single optical fibers 3 arranged in parallel, but this is not limiting. Figures 5(a) to 5(c) are diagrams showing an intermittently bonded optical fiber ribbon 10a corresponding to Figures 3(a) to 3(c).

[0049] The intermittently bonded optical fiber ribbon 10a is configured by arranging parallel optical fiber core wires 3a, which are two-core optical fiber ribbon core wires in which two optical fiber strands are connected in the longitudinal direction. For example, the optical fiber core wires 3a are ribbon core wires that are continuously connected in the longitudinal direction. That is, in the intermittently bonded optical fiber ribbon 10a, adjacent two-core optical fiber ribbon core wires (optical fiber core wires 3a) are intermittently bonded at bonding portions 21 formed at predetermined intervals in the longitudinal direction of the optical fiber ribbon core wire.

[0050] In this embodiment, a pair of optical fibers 3a bonded at a bonding portion 21 forms the connected body 17. At this time, the four single-core optical fibers constituting the connected body 17 at the bonding portion 21 are arranged, for example, in a straight line. Therefore, in a cross section perpendicular to the longitudinal direction of the optical fiber ribbon at the position of any of the bonding portions 21, the arrangement direction (straight line E in FIG. 5(a)) of the optical fibers 3a bonded at the bonding portion 21 (connected body 17) is inclined with respect to the parallel direction D of the optical fibers. Note that even in this case, the average angle of this inclination (straight line θ in FIG. 5(a)) is preferably 1 degree or more and 20 degrees or less, more preferably 1 degree or more and 10 degrees or less.

[0051] 6, a pair of optical fibers 3a constituting the connected body 17 at the bonding portion 21 may not be arranged in a straight line but may have a predetermined angle therebetween. In this case, the center line of the arrangement direction of the optical fiber strands in one optical fiber strand 3a (F1 in the figure) and the arrangement direction of the optical fiber strands in the other optical fiber strand 3a (F2 in the figure) is set to be the arrangement angle E of the optical fibers 3a (connected body 17) bonded at the bonding portion 21 with respect to the parallel direction D of the optical fiber strands.

[0052] In this way, the individual optical fibers constituting the intermittently bonded optical fiber ribbon may be single fibers or ribbons. [Example]

[0053] Various intermittently bonded optical fiber ribbons were manufactured using single-core optical fiber core wires with a transmission loss of 0.20 dB / km, and the transmission loss and fusion workability were evaluated. First, a 16-core intermittently bonded optical fiber ribbon was cut at the bonded position and the cross section was observed, and the average angle (θ) of the optical fiber arrangement of each connected body at the splice was measured using a microscope and the average was calculated.

[0054] Based on the measurement results, nine 16-core intermittently adhesive optical fiber ribbons were twisted together using average angles θ of the optical fiber arrangement at the adhesive joint of ≒ 1°, 5°, 10°, 15°, 20°, 0°, and 30°, and a 144-core unit was constructed by wrapping a 2mm-wide plastic ribbon around them. 48 144-core units were supplied and twisted in four layers in a 2-9-15-22 arrangement, after which absorbent nonwoven fabric was attached lengthwise, rolled in a forming jig, and wrapped with nylon holding thread to create a 6912-core cable core.

[0055] The cable was created by combining the cable core thus created with a 2.0mm diameter G-FRP tension member and a sheath made of a rip cord to cut the sheath into a cylindrical shape with the outer sheath material. The outer sheath material was LLDPE. Using the above steps, 6912-fiber optical fiber cables with θ ≒ 1 degree, 5 degrees, 10 degrees, 15 degrees, 20 degrees, 0 degrees, and 30 degrees were created.

[0056] Similarly, a 16-fiber intermittently bonded optical fiber ribbon was manufactured using a 2-fiber ribbon with a transmission loss of 0.20 dB / km. First, eight 2-fiber ribbons were used, and an adhesive was intermittently applied and cured along the length of the 2 x 8 optical fiber ribbon to create a 16-fiber intermittently bonded optical fiber ribbon. For each connected fiber at the splice, average angles θ of the optical fiber arrangement in the connected fiber were set to ≈ 1°, 5°, 10°, 15°, 20°, 0°, and 30°, and 6912-fiber cables were manufactured for each, in the same way as for the 1 x 16-fiber ribbon.

[0057] The sheath at the end of each of the 6,912-fiber optical fiber cables was peeled off, and the 16-fiber intermittently bonded optical fiber ribbon was taken out, and the transmission loss was confirmed for each average angle (θ) of the optical fiber arrangement at the splice.

[0058] The transmission loss was measured for all optical fibers, and a rate of 95% or more of the optical fibers with a transmission loss of 0.25 dB / km or less after cable assembly was deemed to be acceptable, and a rate of less than 95% was deemed to be unacceptable.

[0059] The coating on the end of each optical fiber ribbon was removed with a fiber stripper, the fiber end faces were exposed with a fiber cutter, and the ribbon was set in a multi-core optical fiber fusion splicer for fusion splicing.

[0060] After 50 attempts, the fusion workability was evaluated as passing if the rate at which the tips of the 16-fiber ribbon fibers were successfully set into the V-groove of the fusion splicer in one try without spreading or crossing after cutting the end face with a fiber cutter was 80% or more. The results are shown in Tables 1 to 3.

[0061] [Table 1]

[0062] [Table 2]

[0063] [Table 3]

[0064] In all of Examples 1 to 10, the rate of transmission loss being 0.25 dB / km or less was 95% or more, and the one-set success rate during fusion work was also 80% or more, which was acceptable. In particular, Examples 1 to 3 and 6 to 8, in which the average angle θ of the optical fiber arrangement at the splice portion was 10 degrees or less, had a one-set success rate during fusion work of over 90%.

[0065] On the other hand, conventional Comparative Examples 1 and 3, which had no rotation angle, had high transmission loss, with less than 95% of the fibers having a transmission loss of 0.25 dB / km or less. Furthermore, Comparative Examples 2 and 4, in which the average angle θ of the optical fiber arrangement at the splice portion exceeded 20 degrees, had a one-time success rate of less than 80% during the fusion splicing operation. Thus, Examples 1 to 10, in which the average angle of the optical fiber arrangement at the splice portion was within the specified range, satisfied both the transmission loss and the fusion splicing workability.

[0066] Although the embodiments of the present invention have been described above with reference to the accompanying drawings, the technical scope of the present invention is not limited to the above-described embodiments. It is clear that those skilled in the art can conceive of various modifications and alterations within the scope of the technical ideas described in the claims, and it is understood that these modifications and alterations also fall within the technical scope of the present invention. [Explanation of symbols]

[0067] 1....Optical fiber cable 3, 3a....Optical fiber core 4... Core part 5....Optical fiber unit 7...Pressing and winding member 9...Tension member 10, 10a....Intermittently adhesive type optical fiber ribbon 11...Tear cord 13……Outer cover 15...Cable core 17……Concatenated body 21……Adhesive part 30.... Ribbon fiber manufacturing equipment 31...Supply drum 33...Dice 35: Resin supply control unit 37...Resin application device 39……Curing device 41...Tension detection device 43....Taking device 45....Winding drum

Claims

1. An optical fiber ribbon in which a plurality of optical fiber core wires are arranged in parallel, Adjacent optical fiber core wires are intermittently bonded together at bonding sections formed at predetermined intervals in the longitudinal direction of the optical fiber ribbon core wire, and the bonding sections adjacent to each other in the parallel direction of the optical fiber core wires are arranged at positions shifted from each other in the longitudinal direction of the optical fiber ribbon core wire, In a cross section perpendicular to the longitudinal direction of the optical fiber ribbon at the position of any one of the adhesive portions, the same cross section has a plurality of the adhesive portions, and when no external force is applied to the optical fiber ribbon, the average angle, which is the average value of the angles of the arrangement directions of the plurality of optical fiber core wires that are respectively bonded at the plurality of adhesive portions located in the same cross section, relative to the parallel direction of the optical fiber core wires, is 1 degree or more and 20 degrees or less, An intermittently bonded optical fiber ribbon, characterized in that the lengths between the bonded portions of adjacent optical fiber core wires in the longitudinal direction are different, and the difference in length between the bonded portions of the adjacent optical fiber core wires changes in the longitudinal direction.

2. The optical fiber ribbon is a two-core optical fiber ribbon in which two optical fiber strands are connected in the longitudinal direction, and adjacent two-core optical fiber ribbons are intermittently bonded at the bonding portions formed at predetermined intervals in the longitudinal direction of the optical fiber ribbon.

3. An intermittently bonded optical fiber ribbon as described in claim 1, characterized in that in a cross section perpendicular to the longitudinal direction of the optical fiber ribbon at the position of any of the bonding portions, the average angle of the arrangement direction of the optical fiber ribbons bonded at the bonding portions relative to the parallel direction of the optical fiber ribbons is 1 degree or more and 10 degrees or less.

4. An optical fiber cable using the intermittently adhesive type optical fiber ribbon according to claim 1, A plurality of the intermittently bonded optical fiber ribbons are twisted together to form an optical fiber unit, A core portion is formed by twisting a plurality of the optical fiber units together, a cable core formed by longitudinally winding a pressure winding member around the outer periphery of the core portion; a tension member disposed outside the cable core; an outer sheath covering the cable core and the tension member; An optical fiber cable comprising:

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