Rollable ribbon

Abstract

In a rollable ribbon (10), a plurality of single-core coated optical fibers (20) arranged in parallel are connected by a plurality of connection parts (30) that are present intermittently. An optical fiber strand (21) included in the single-core coated optical fibers has a mode field diameter of 9.2 μm, which is a nominal value in compliance with ITU-T G.657.A1, at the wavelength of 1310 nm. When the length of each of the connection parts (10) in the length direction of the rollable ribbon (10) is denoted by A, and when the length, in the length direction of the rollable ribbon (10), between two of the connection parts (30) in three of the single-core coated optical fibers (201, 202, 203) arranged side by side in the width direction of the rollable ribbon is denoted as C, C≥A is satisfied, and C is 15 mm or more.

Description

Rollable optical fiber ribbon

[0001] The present invention relates to a rollable optical fiber ribbon.

[0002] Data centers and the like have been increasingly constructed in countries around the world, and rollable optical fiber ribbons that enable high density have been widely used (see Patent Document 1). For rollable optical fiber ribbons, an optical fiber that conforms to ITU-T G.657.A1 and has a mode field diameter center of 8.6 µm at a wavelength of 1310 nm is used. In recent years, there has been an increasing demand for the use of optical fibers having a mode field diameter center of 9.2 µm at 1310 nm, which can accommodate a wide range of applications unrelated to data center use.

[0003] Japanese Patent No. 6188097

[0004] However, in a rollable optical fiber ribbon using an optical fiber that conforms to ITU-T G.657.A1 and has a mode field diameter center of 9.2 µm at a wavelength of 1310 nm, for example, transmission loss of light with a wavelength of 1550 nm at low temperatures such as -40°C is large. The main object of the present invention is to provide a rollable optical fiber ribbon capable of suppressing transmission loss at low temperatures.

[0005] According to the present invention for solving the above problem, there is provided a rollable optical fiber ribbon in which a plurality of single-core coated optical fibers arranged in parallel are connected for each single core by a plurality of intermittently provided connecting portions, wherein the optical fiber included in the single-core coated optical fiber conforms to ITU-T G.657.A1, and has a mode field diameter center of 9.2 µm at a wavelength of 1310 nm; when, in the length direction of the rollable optical fiber ribbon, the length of the connecting portion is defined as A, and for the three single-core coated optical fibers arranged adjacent to each other in the width direction of the rollable optical fiber ribbon, which are respectively defined as a first single-core coated optical fiber, a second single-core coated optical fiber, and a third single-core coated optical fiber in the arrangement order, the length in the length direction of the rollable optical fiber ribbon between a connecting portion for connecting the first single-core coated optical fiber and the second single-core coated optical fiber and a connecting portion for connecting the second single-core coated optical fiber and the third single-core coated optical fiber is defined as C, C ≥ A, and C is 15 mm or more. A rollable optical fiber ribbon is thus provided.

[0006] According to the present invention, a rollable ribbon can be provided that can suppress transmission loss at low temperatures.

[0007] Figures 1A to 1C are schematic diagrams showing a rollable ribbon. Figure 2 is a diagram showing the schematic configuration of a rolling ribbon manufacturing apparatus. Figures 3A and 3B are schematic diagrams showing the configuration of the removal section. Figures 4A and 4B are schematic diagrams showing the configuration of the rotating blade. Figure 5 is a flowchart of the method for manufacturing a rollable ribbon. Figure 6 is a graph showing the temperature cycle test results of a rollable ribbon according to Comparative Example 1. Figure 7A is a graph showing the temperature cycle test results of a rollable ribbon according to Comparative Example 2, and Figure 7B is a graph showing the temperature cycle test results of a rollable ribbon according to Example 1. Figure 8 is a schematic diagram showing how the single-core coated optical fiber of a rollable ribbon meanders at low temperatures.

[0008] Hereinafter, a rollable ribbon according to a preferred embodiment of the present invention, as well as a manufacturing apparatus and method thereof, will be described. In this specification, with respect to the notation "~" indicating a numerical range, the lower limit and upper limit are included in that numerical range.

[0009] First, a description of the rollable ribbon will be given, followed by a description of the manufacturing apparatus and manufacturing method for the rollable ribbon. In the following description, the direction in which the single-core coated optical fibers are arranged in parallel will be referred to as the first direction D1, the length direction of the single-core coated optical fibers will be referred to as the second direction D2, and the direction perpendicular to the first direction D1 and the second direction D2 will be referred to as the third direction D3. The first direction D1 corresponds to the width direction of the rollable ribbon, the second direction D2 corresponds to the length direction of the rollable ribbon, and the third direction D3 corresponds to the thickness direction of the rollable ribbon.

[0010] [Structure of the Rollable Ribbon] Figure 1A is a schematic plan view of the rollable ribbon 10, Figure 1B is a cross-sectional view of line A-A in Figure 1A, and Figure 1C is a cross-sectional view of line B-B in Figure 1A.

[0011] As shown in Figures 1A to C, the rollable ribbon 10 has multiple single-core coated optical fibers (hereinafter also simply referred to as "optical fibers") 20, multiple connecting portions 30, and multiple separating portions 40. In Figure 1A, the connecting portions 30 are shown in black to make them easier to distinguish from the separating portions 40.

[0012] Multiple optical fibers 20 are arranged in parallel in a first direction D1. The number of optical fibers 20 is not particularly limited as long as there are three or more. The number of optical fibers 20 included in one rollable ribbon 10 is appropriately selected depending on the application of the rollable ribbon 10. For example, the number of optical fibers 20 included in one rollable ribbon 10 is in the range of 3 to 12. In this embodiment, 12 optical fibers 20 are arranged in parallel in one rollable ribbon 10.

[0013] As shown in Figures 1B and 1C, the single-core coated optical fiber 20 has optical fiber strands 21, a primary coating layer 22, and a secondary coating layer 23. The primary coating layer 22 and the secondary coating layer 23 can be the same as those of known primary and secondary coating layers of optical fibers, respectively.

[0014] On the other hand, the optical fiber strand 21 has the basic performance described above. Specifically, the optical fiber strand 21 has a mode field diameter center of 9.2 μm at a wavelength of 1310 nm, in accordance with ITU-T G. 657. A1. It has been found that a rollable ribbon 10 made using an optical fiber strand 21 with such basic performance exhibits high transmission loss at low temperatures. However, transmission loss can be suppressed if the conditions for the length A of the connecting portion 30, the length C between the connecting portions 30, and the pitch P of the connecting portions 30, as described later, are met.

[0015] The smaller the outer diameter of the single-core coated optical fiber 20, the more desirable it is for increasing the density of the rollable ribbon 10. From this viewpoint, the outer diameter of the single-core coated optical fiber 20 is preferably 300 μm or less, 280 μm or less, 250 μm or less, or 200 μm or less. On the other hand, if the single-core coated optical fiber is too thin, it may become difficult to manufacture. From this viewpoint, the lower limit of the outer diameter of the single-core coated optical fiber can be, for example, 180 μm or more.

[0016] A colored layer may be further formed on the secondary coating layer 23 of the optical fiber 20. It is preferable that the colors of the colored layers of multiple optical fibers 20 within a single rollable ribbon 10 are different from each other. This allows for the identification of multiple optical fibers 20 within a single rollable ribbon 10.

[0017] In this embodiment, multiple optical fibers 20 are covered by a tape layer 41, and adjacent optical fibers 20 are partially connected by the tape layer 41. In this embodiment, the portion of the tape layer 41 that connects adjacent optical fibers 20 is the connecting portion 30, and the space that separates adjacent optical fibers 20 (the area without the tape layer 41) is the separating portion 40. Note that the tape layer 41 does not have to completely cover the periphery of the optical fibers 20. For example, the optical fibers 20 may be partially exposed around the separating portion 40.

[0018] The connecting portion 30 is positioned between adjacent optical fibers 20, partially connecting them. On the other hand, the separating portion 40 is positioned between adjacent optical fibers 20, partially separating them. As shown in Figure 1A, the connecting portion 30 connects each of the multiple single-core coated optical fibers 20 in the rollable ribbon 10, one core at a time.

[0019] In the rollable ribbon 10 of this embodiment, connecting portions 30 and separating portions 40 are arranged alternately in the longitudinal direction (second direction D2) of the rollable ribbon 10. That is, the connecting portions 30 are arranged intermittently in the longitudinal direction (second direction D2) of the rollable ribbon 10.

[0020] The longitudinal arrangement of the connecting portion 30 and the separating portion 40 is preferably as follows in order to suppress light transmission loss at low temperatures. That is, as shown in Figure 1A, when the length of the connecting portion 30 is A and the length of the separating portion 40 corresponding to the space between two adjacent connecting portions 30 is B in the longitudinal direction of the rollable ribbon 10, the pitch P in which the connecting portions 30 represented by A + B are arranged is preferably 90 mm or more and 120 mm or less. Furthermore, as shown in Figure 1A, the three single-core coated optical fibers 20 arranged adjacent to each other in the width direction of the rollable ribbon 10 are designated as the first single-core coated optical fiber 201, the second single-core coated optical fiber 202, and the third single-core coated optical fiber 203, respectively, in the order they are arranged. When C is the length in the longitudinal direction of the rollable ribbon 10 between the connecting portion 30 for connecting the first single-core coated optical fiber 201 and the second single-core coated optical fiber 202 and the connecting portion 30 for connecting the second single-core coated optical fiber 202 and the third single-core coated optical fiber 203, C ≥ A, and it is preferable that C is 15 mm or more. Note that the above three single-core coated optical fibers 20 can be any three single-core coated optical fibers 20 arbitrarily selected in the rollable ribbon 10. Furthermore, the connecting portion 30 for connecting the first single-core coated optical fiber 201 and the second single-core coated optical fiber 202, and the connecting portion 30 for connecting the second single-core coated optical fiber 202 and the third single-core coated optical fiber 203, are two adjacent connecting portions 30 in the longitudinal direction of the rollable ribbon 10 for the three single-core coated optical fibers. By satisfying the above conditions A, B, C, and P, transmission loss at low temperatures can be suppressed. The reason for this is presumed to be as follows.

[0021] In other words, when viewing a single optical fiber along its length, the connecting portions 30 are arranged alternately on the left and right (up and down in Figure 1A) of the optical fiber. To put it another way, if we focus on a single optical fiber in Figure 1A (for example, the second single-core coated optical fiber 202 in Figure 1A), the connecting portions 30 are arranged alternately at the bottom, top, bottom, and top. In this state, if the connecting portions 30 contract at low temperatures, the optical fiber 20 is pulled towards each connecting portion 30 and bends, as shown in Figure 8. It is presumed that this meandering causes bending loss, resulting in transmission loss at low temperatures. In contrast, if the pitch P is made longer, such as 90 mm or more, and C ≥ A, and C is 15 mm or more, even if the optical fiber 20 bends, the radius of curvature becomes larger, so it is presumed that bending loss is suppressed and transmission loss at low temperatures is suppressed. Specifically, as shown in Figure 8, the occurrence of transmission loss is suppressed when the radius of curvature r of the S-shaped deflection of the optical fiber 20, which is connected to and pulled by the connecting portion 30 that contracts in an environment of -40°C, becomes 15 mm or more (see the dotted circle along the S-curve of the second single-core coated optical fiber 202 in Figure 8). This radius of curvature r (15 mm or more) is recognized as common technical knowledge in ITU-T G. 657. A1 as a functional guarantee value that does not cause large transmission loss. It is more preferable that the radius of curvature r be 20 mm or more, and even more preferable that it be 25 mm or more. Note that this mechanism by which transmission loss is suppressed at low temperatures is a hypothesis and does not limit the present invention. Further details on this will be described later with reference to examples.

[0022] The upper limit of the pitch P is preferably 120 mm or less. If the pitch P exceeds 120 mm, the ease of connecting the rollerable ribbon 10 may decrease. Also, C should be 15 mm or more, and can be 18 mm or more, or 20 mm or more. There is no particular upper limit to C, or it can be, for example, 30 mm or less, 25 mm or less, or 20 mm or less.

[0023] Furthermore, in the rollable ribbon 10, the connecting portions 30 are intermittently arranged in the width direction (first direction D1) of the rollable ribbon 10. In the intermittent configuration, it is preferable that two or more separating portions 40 are arranged between adjacent connecting portions 30 in the width direction (first direction). In the rollable ribbon 10 of this embodiment, two separating portions 40 are arranged between adjacent connecting portions 30 in the width direction (first direction D1) of the rollable ribbon 10. This reduces the number of connecting portions 30, thereby shortening the overall width of the rollable ribbon 10. It is also preferable that the multiple separating portions 40 are arranged such that the range of existence of two adjacent separating portions 40 in the length direction (second direction D2) of the rollable ribbon 10 partially overlaps in the width direction (first direction D1) of the rollable ribbon 10.

[0024] As shown in Figure 1A, the length A of the connecting portion 30 when the rollable ribbon 10 is viewed from above is equal to or less than C. Therefore, A only needs to be 20 mm or less in relation to C, and can be 18 mm or less, or 15 mm or less. The lower limit of A is not particularly limited, or for example, 5 mm or more. Also, the length B of the separating portion 40 is, for example, within the range of 60 mm to 130 mm, or 75 mm to 100 mm.

[0025] The thickness T of the connecting portion 30, as shown in Figure 1B, is not particularly limited. The thickness T is, for example, within the range of 200 μm to 290 μm. When the length A and thickness T of the connecting portion 30 are within this range, the strength of the connecting portion 30 is increased, and the connecting portion 30 is less likely to tear even when the rollable ribbon 10 is wound or twisted in the width direction. When the length B of the separating portion 40 is within this range, it becomes easier to wind or twist the rollable ribbon 10 in the width direction when housing the rollable ribbon 10 inside the cable. In this embodiment, the lengths A, B, C, and T are the average values ​​when measured at any five locations within the rollable ribbon 10.

[0026] The tape layer 41 is composed of a resin or a resin composition. That is, the tape layer 41 contains resin, and the connecting portion 30 also contains resin. The type of resin is not particularly limited, but for example, it may be a photocurable resin or a thermosetting resin. In this embodiment, the resin contained in the tape layer 41 is a cured product of a photocurable resin. Examples of photocurable resins include urethane resins and epoxy resins.

[0027] In the width direction (first direction D1) of the rollable ribbon 10, the optical fiber 20 between the two separated portions 40 is covered with a tape layer 41, although it is not connected by a connecting portion 30. The shape of the cross-section of the optical fiber 20, including the tape layer 41, is not particularly limited and may be, for example, substantially rectangular or substantially circular. In this embodiment, as shown in Figure 1C, the cross-section of the optical fiber 20, whose entire circumference is covered with the tape layer 41, is substantially rectangular. The pitch in which the optical fibers 20 are arranged in the width direction (first direction D1) of the rollable ribbon 10 (the distance between the centers of adjacent optical fiber strands in the first direction D1) can be appropriately set to match existing rollable ribbons. This pitch is, for example, about 250 μm.

[0028] [Configuration of the Rollable Ribbon Manufacturing Apparatus] Next, the rollerable ribbon manufacturing apparatus 100 will be described. Figure 2 is a perspective view of the rollerable ribbon manufacturing apparatus 100.

[0029] As shown in Figure 2, the rollerable ribbon manufacturing apparatus 100 has a coating section 110, a removal section 120, and a hardening section 140. The rollerable ribbon manufacturing apparatus 100 manufactures a rollerable ribbon 10 in which adjacent optical fibers 20 are partially connected, by feeding a plurality of optical fibers 20 arranged in parallel in a first direction D1 in a second direction D2 which is the longitudinal direction of the plurality of optical fibers 20.

[0030] The coating portion 110 forms an uncured tape layer 41 by coating a plurality of optical fibers 20 arranged in parallel at a predetermined pitch with an uncured photocurable resin (hereinafter also simply referred to as "uncured resin"). The configuration of the coating portion 110 is not particularly limited as long as it can perform the above functions. In this embodiment, the coating portion 110 has a die (not shown). The die has an insertion hole through which a plurality of optical fibers 20 arranged in parallel in a first direction D1 pass, and the shape of the opening of the insertion hole is the shape of a cross-section perpendicular to the length direction of the tape layer 41. The coating portion 110 can form a tape layer 41 on a plurality of optical fibers 20 in a continuous manner by coating the plurality of optical fibers 20 that are sent in a state where they are arranged in parallel at a predetermined pitch with an uncured resin using the die.

[0031] The removal unit 120 partially removes the uncured resin between adjacent optical fibers 20 from the uncured resin covering the entire surface of the multiple optical fibers 20, thereby forming a separated portion 40 where adjacent optical fibers 20 are partially separated, and a connected portion 30 where adjacent optical fibers 20 are partially connected. The removal unit 120 should form the separated portion 40 and the connected portion 30 in such a way that it satisfies the conditions of the pitch P and C of the arrangement of the connected portion 30.

[0032] The configuration of the removal unit 120 is not particularly limited as long as it can perform the above-mentioned function. Figures 3A and 3B are diagrams illustrating an example of the removal unit 120 shown in Figure 2. Figure 3A is a plan view of the removal unit 120, and Figure 3B is a cross-sectional view along the line A-A in Figure 3A.

[0033] As shown in Figures 3A and 3B, the removal unit 120 includes a rotating blade 121 for removing uncured resin, a positioning unit 122 for positioning a plurality of parallel-arranged optical fibers 20, and a suction unit 123 for sucking up the removed uncured resin. In Figure 3A, the positioning unit 122 is represented by a solid line, and a part of the removal unit 120 is shown by a dashed line. In Figure 3B, the positioning unit 122 and the suction unit 123 are represented by solid lines, and the optical fibers 20 positioned by the positioning unit 122 are shown by a dashed line.

[0034] As shown in Figures 3A and 3B, multiple rotating blades 121 are arranged within the positioning unit 122, and the rotating blades 121 are aligned in a first direction D1 so as to remove the resin between the multiple parallel-arranged optical fibers 20. Multiple slits 126 are also aligned in the first direction D1 to correspond to the multiple rotating blades 121. The uncured resin removed by the rotating blades 121 is collected through the slits 126 by being sucked up by the suction unit 123.

[0035] Figures 4A and 4B are schematic diagrams showing the configuration of the rotating blade 121. Figure 4A shows only one rotating blade 121, and Figure 4B shows three rotating blades 121. As shown in Figure 4A, in this embodiment, the rotating blade 121 has a notch 128 and a blade portion 129. The circumferential length of the notch 128 corresponds to the length of the connecting portion 30, and the circumferential length of the blade portion 129 corresponds to the length of the separation portion 40. As such a rotating blade 121 rotates, the uncured resin is intermittently removed. The circumferential lengths of the notch 128 and the blade portion 129 of the rotating blade 121 should be appropriately designed to satisfy the pitch P of the connecting portion 30 as described above. The number of rotating blades 121 is the same as the number of slits 126.

[0036] The rotating blade 121 is preferably positioned in a third direction D3 such that it can remove uncured resin between the multiple optical fibers 20 being transported. Specifically, the rotating blade 121 is positioned such that the top of the blade portion 129 when rotated is above the upper end of the optical fiber 20 in the direction of the third direction D3 from which it is being transported. The rotation of the multiple rotating blades 121 is controlled by a motor (not shown) and rotates in accordance with the transport of the optical fibers 20, and their rotation axes 127 coincide. The shapes of the multiple rotating blades 121 may all be the same, or they may each be different. In this embodiment, all of the multiple rotating blades 121 have the same shape.

[0037] The multiple rotating blades 121 shown in Figure 4B are arranged such that the positions of the notches 128 differ between adjacent rotating blades 121. As the rotating blades 121 rotate in accordance with the transport of the optical fiber 20, the multiple rotating blades 121 rotate while the positions of the notches 128 of each rotating blade 121 remain different, and connecting portions 30 and separating portions 40 are alternately formed. The position of each notch 128 on the multiple rotating blades 121 is appropriately set according to the positions of the connecting portions 30 and separating portions 40 on the rollable ribbon 10. Specifically, when a notch 128 is located between adjacent optical fibers 20, the uncured photocurable resin is not pushed out, and a connecting portion 30 is formed. On the other hand, when a blade 129 is located between adjacent optical fibers 20, the uncured resin is pushed out from between the adjacent optical fibers 20, so the uncured resin no longer exists between the adjacent optical fibers 20, and a separating portion 40 is formed.

[0038] Although not specifically shown in the figures, it is preferable that the rotating blade 121 is positioned such that the distance between the rotating blade 121 and the optical fiber 20 is in the range of 0 to 10 μm, and more preferably in the range of 0 to 5 μm. By shortening the distance between the rotating blade 121 and the optical fiber 20 in this way, the tape layer 41 formed on the side surface of the optical fiber 20 can be made thinner (see Figure 1B).

[0039] The positioning unit 122 determines the position of the optical fiber 20 that will undergo the removal operation of uncured resin. The positioning unit 122 has a positioning unit body 124, a through hole 125, and a plurality of slits 126. The slits 126 also have an exit opening 126a. The through hole 125 and the slits 126 are provided in the positioning unit body 124, respectively.

[0040] In this embodiment, the positioning unit body 124 is formed in a substantially rectangular parallelepiped shape. The positioning unit body 124 has through holes 125 for passing multiple optical fibers 20 through, multiple slits 126 for each of the multiple rotating blades 121 to rotate inside, and multiple outlet openings 126a of the slits 126 from which the resin extruded by the multiple rotating blades 121 comes out.

[0041] The through-hole 125 allows multiple optical fibers 20, which are coated with uncured resin, to pass through. In this embodiment, the through-hole 125 opens on the back surface 124a (right side in Figure 3B) and the front surface 124b (left side in Figure 3B) of the positioning unit body 124. The cross-sectional shape of the through-hole 125 in the direction along the third direction D3 and the first direction D1 is complementary to the cross-section of the optical fiber 20 coated with uncured resin.

[0042] Multiple slits 126 are configured so that multiple rotating blades 121 can rotate inside them. The multiple slits 126 are arranged along the second direction D2 and in parallel along the first direction D1. The exit opening 126a of the slit 126 opens onto the surface (top surface in this embodiment) of the positioning unit body 124 on the suction unit 123 side. The downstream end of the slit 126 opens onto the front surface 124b of the positioning unit body 124. The multiple slits 126 may all be the same shape, or they may all be different shapes. In this embodiment, all the multiple slits 126 are the same shape. The number of slits 126 should be equal to or greater than the number of spaces between adjacent optical fibers 20. In this embodiment, the number of spaces between adjacent optical fibers 20 is 11, so there are 11 slits 126.

[0043] Since the rotating blade 121 is positioned in the slit 126, the uncured resin is pushed out from the exit opening 126a of the slit 126. Also, as described above, since the rotating blade 121 follows the transport of the optical fiber 20, stress is generated in the direction of the optical fiber 20's movement on the uncured resin pushed out from the slit 126 by the rotating blade 121. At this time, since the downstream end of the slit 126 opens to the front surface 124b of the positioning unit body 124, the uncured resin does not get stuck and is prevented from coming into contact with the optical fiber 20 again.

[0044] The suction unit 123 sucks up the uncured resin extruded from the outlet opening 126a of the slit 126. The suction unit 123 has an intake unit 131, a negative pressure device (not shown), and a connecting unit 132 for connecting the intake unit 131 and the negative pressure device.

[0045] The intake section 131 is formed in a hollow box shape having a suction opening 131a disposed so as to cover the plurality of outlet openings 126a of the plurality of slits 126 from which the resin pushed out by the plurality of rotating blades 121 exits. It is preferable that the downstream end of the suction opening 131a is disposed further downstream than the downstream ends of the plurality of outlet openings 126a. This allows proper suction of uncured resin that has accumulated downstream of the plurality of outlet openings 126a, and can prevent the uncured resin accumulated downstream of the plurality of outlet openings 126a from coming into contact with the optical fibers 20 again. Furthermore, the upstream end of the suction opening 131a is disposed further upstream than the upstream ends of the plurality of outlet openings 126a. In the present embodiment, the upstream end of the suction opening 131a is disposed at the same position as the upstream ends of the plurality of outlet openings 126a.

[0046] Furthermore, the length of the suction opening 131a in the arrangement direction of the plurality of optical fibers 20 (first direction D1) is preferably within a range of 100% to 120% of the length of the plurality of outlet openings 126a in the arrangement direction of the plurality of optical fibers 20. Here, the "length L1 of the plurality of outlet openings 126a in the arrangement direction of the plurality of optical fibers 20" refers to the distance between the outer end of the slit 126 disposed at one end in the first direction D1 (in the example shown in FIG. 3A, the outer end of the lowermost slit 126) and the outer end of the slit 126 disposed at the other end in the first direction D1 (in the example shown in FIG. 3A, the outer end of the uppermost slit 126). This reduces the volume of the space surrounded by the upper surfaces of the intake section 131 and the positioning section main body 124, allowing the suction device to efficiently create negative pressure in the space. Therefore, the uncured resin can be efficiently and appropriately sucked.

[0047] The connecting portion 132 connects the intake portion 131 and a negative pressure device not shown in the figure. In the present embodiment, the connecting portion 132 is connected to the surface of the intake portion 131 on the opposite side to the suction opening 131a. By operating the negative pressure device, the interior of the intake portion 131 can be brought into a negative pressure state, and further, the space surrounded by the upper surfaces of the intake portion 131 and the positioning portion main body 124 can be brought into a negative pressure state. It is preferable that the magnitude of the negative pressure is appropriately adjusted so as not to suck the uncured resin remaining around the plurality of optical fibers 20, but to suck only the uncured resin extruded into the space. The condition for sucking only the uncured resin extruded into the space is appropriately adjusted depending on the volume of the space and the suction pressure of the negative pressure device. It is preferable that the negative pressure device is constantly operated during the production of the rollable ribbon 10.

[0048] The curing portion 140 cures the uncured resin remaining on the plurality of optical fibers 20. The configuration of the curing portion 140 is not particularly limited as long as it can exhibit this function. In the present embodiment, the curing portion 140 includes a first light irradiation portion 141 and a second light irradiation portion 142. The first light irradiation portion 141 is arranged on the upstream side, and irradiates the tape layer 41 with light to semi-cure the uncured tape layer 41. The second light irradiation portion 142 further irradiates light to completely cure the semi-cured tape layer 41. In the present embodiment, the integrated irradiation dose of the first light irradiation portion 141 on the upstream side and the second light irradiation portion 142 on the downstream side are adjusted such that the integrated irradiation dose of the first light irradiation portion 141 is smaller and the integrated irradiation dose of the second light irradiation portion 142 is larger.

[0049] [Method for Producing Rollable Ribbon] Next, a method for producing a rollable ribbon will be described. FIG. 5 is a flowchart of the method for producing a rollable ribbon.

[0050] As shown in FIG. 5, the method for producing a rollable ribbon includes: a step of coating a plurality of optical fibers with an uncured resin (S110); a step of partially removing the uncured resin (S120); and a step of curing the resin (S130).

[0051] In the step of coating multiple optical fibers with an uncured resin (S110), multiple optical fibers 20 arranged in parallel at a predetermined pitch are coated with an uncured resin. Here, it is preferable to select and use a resin in which the elongation at break after curing is 24% or more. For example, the coating section 110 of the manufacturing apparatus shown in Figure 2 may be used to form the uncured tape layer 41. Specifically, while feeding the multiple optical fibers 20, the uncured resin is applied in a tape-like manner to the multiple optical fibers 20 using a die to form the tape layer 41.

[0052] In the step of partially removing the uncured resin (S120), the uncured resin between adjacent optical fibers 20 coated with uncured resin is partially removed. The removal of the uncured resin should be carried out in a manner that satisfies the above-mentioned conditions of length A, length B, length C, and pitch P. For example, the connecting portion 30 and the separating portion 40 can be formed using the removal unit 120 of the manufacturing apparatus shown in Figures 2, 3A, and 3B. Specifically, a plurality of rotating blades 121 are rotated on the tape layer 41 to remove a portion of the tape layer 41 and form the connecting portion 30 and the separating portion 40 in a manner that satisfies the conditions of length A, length B, length C, and pitch P. At this time, the uncured resin removed by the rotating blades 121 is pushed out toward the exit opening 126a of the slit 126. The uncured resin pushed out from the exit opening 126a of the slit 126 is sucked up by the suction unit 123.

[0053] In the resin curing step (S130), the uncured resin remaining on the multiple optical fibers 20 is cured. For example, the curing unit 140 of the manufacturing apparatus shown in Figure 2 may be used to partially cure the uncured tape layer 41 by irradiating it with light from the first light irradiation unit 141, and then completely cure the partially cured tape layer 41 by irradiating it with light from the second light irradiation unit 142. The elongation at break of the cured resin is 24% or more.

[0054] By following the above procedure, a rollable ribbon 10 can be manufactured in which the connecting portion 30 and its surrounding area satisfy predetermined conditions.

[0055] (Effects) As described above, according to the embodiment of the present invention, a rollable ribbon can be provided that can suppress transmission loss at low temperatures by ensuring that the connecting portion and its surrounding area meet predetermined conditions.

[0056] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples.

[0057] Rollable ribbons of Comparative Example 1-2 and Example 1-2 were manufactured using 12 optical fibers, and their transmission performance at low temperatures was investigated. Table 1 shows the center of the mode field diameter of the optical fiber strands used in the manufacture of each rollable ribbon. In addition, Table 1 also shows the length A of the connecting section, the length B of the separated section, and the pitch P of the connecting section in each rollable ribbon. The transmission performance at low temperatures was investigated by performing a temperature cycle test in accordance with IEC 60794-1-22, TIA-455-3, using a wavelength of 1550 nm and repeatedly changing the temperature from -40°C to 70°C. It is desirable that the variation in the transmission loss of the rollable ribbon in this test, relative to the transmission loss at room temperature of 23°C, is 0.05 dB or less.

[0058]

[0059] Graphs of the test results for Comparative Examples 1-2 and Example 1 are shown in Figures 6 and 7. The data shown by the 12 broken lines in each of Figures 6 and 7 corresponds to the 12 optical fibers in the rollable ribbon.

[0060] As can be seen from the comparison of the graphs in Figure 6 and Figure 7A, when the center of the mode field diameter is changed from 8.6 μm to 9.2 μm, the variation in transmission loss at low temperatures of -40°C increases when the pitch P of the connecting part is less than 90 mm. This is thought to be because the connecting part contracts at low temperatures, causing the two optical fibers to move closer to each other in the width direction, which bends the optical fibers and causes bending loss. In contrast, as shown in Figure 7B, in Example 1-2, where the center of the mode field diameter is 9.2 μm and the pitch P of the connecting part is 90 mm or more and 120 mm or less, the variation in transmission loss at low temperatures of -40°C was suppressed. This is thought to be because in the rollable ribbon of Example 1-2, the pitch P of the connecting part is larger than the pitch P of Comparative Example 2, and in particular C ≥ A, with C being 15 mm or more, so even if the connecting part contracts at low temperatures and causes the two optical fibers to move closer to each other in the width direction, the bending of the optical fibers to a small diameter is suppressed. Specifically, this is thought to be because the radius of curvature of the meandering optical fiber is 15 mm or more.

[0061] This application claims priority under the international application PCT / JP2025 / 006358, filed on 25 February 2025. All content described in the specification and drawings of said application is incorporated herein by reference.

[0062] The rollable ribbon according to the present invention is useful for suppressing transmission loss at low temperatures.

[0063] 10 Rollable ribbon 20 Optical fiber (single-core coated optical fiber) 21 Optical fiber strand 22 Primary coating layer 23 Secondary coating layer 30 Connecting part 40 Separating part 41 Tape layer 100 Manufacturing apparatus 110 Coating part 120 Removal part 121 Rotating blade 122 Positioning part 123 Suction part 124 Positioning part body 124a Back view 124b Front view 125 Through hole 126 Slit 126a Exit opening 127 Rotating shaft 128 Notch part 129 Blade part 131 Intake part 131a Suction opening 132 Connection part 140 Hardening part 141 First light irradiation part 142 Second light irradiation part 201 First single-core coated optical fiber 202 Second single-core coated optical fiber 203 Third single-core coated optical fiber

Claims

1. A rollable ribbon comprising a plurality of single-core coated optical fibers arranged in parallel, each connected by a plurality of intermittently existing connecting sections, wherein the optical fiber strands of the single-core coated optical fibers have a mode field diameter center of 9.2 μm at a wavelength of 1310 nm, in accordance with ITU-T G.

657. A1, and the length of the connecting section in the longitudinal direction of the rollable ribbon is A, and the three single-core coated optical fibers arranged adjacent to each other in the width direction of the rollable ribbon are designated as the first single-core coated optical fiber, the second single-core coated optical fiber, and the third single-core coated optical fiber in the longitudinal direction of the rollable ribbon, respectively, and the length of the connecting section for connecting the first single-core coated optical fiber and the second single-core coated optical fiber and the connecting section for connecting the second single-core coated optical fiber and the third single-core coated optical fiber in the longitudinal direction of the rollable ribbon is C, wherein C ≥ A, and C is 15 mm or more.

2. A rollable ribbon according to claim 1, characterized in that when the length of the gap between two adjacent connecting portions is B, the pitch P in which the connecting portions represented by A + B are arranged is 90 mm or more and 120 mm or less.

3. A rollable ribbon according to claim 2, characterized in that A is 5 mm or more and 20 mm or less, and B is 75 mm or more and 100 mm or less.

4. A rollable ribbon according to claim 3, characterized in that, in a temperature cycle test in which the temperature changes from -40°C to 70°C are repeated, the amount of variation based on the transmission loss at room temperature of 23°C is 0.05 dB or less.

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