JP2009140767A - Multicore wire group knitting method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a multicore wire group knitting method achieving bending of the wire group in an arbitrary direction. <P>SOLUTION: In a plurality of wires aligned at their leading ends, one of two side wires at both sides is made alternately intersect a wire prepared between the one of side wires at both the sides and one of central wires at the center in order starting from an outer side wire toward one central wire on the same side as the one side wire viewed from the center, and the other side wire of the two side wires at both the sides is made alternately intersect a wire prepared between the other of the side wires at both the sides and the other of the two central wires at the center in order starting from an outer side wire toward the other central wire on the same side as the other side wire viewed from the center. Then, one central wire is made intersect the other central wire. The above operations are repeated until each wire is returned to its original position. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for weaving a multi-core fiber group such as a multi-fiber fiber.

  Conventionally, as shown in FIG. 10 (a), a multi-fiber optical fiber has a plurality of optical fibers arranged in parallel and integrated into a tape shape with a resin coating to form a tape shape (that is, an optical fiber tape core wire) 1. It was common to make it. That is, in FIG. 10 (a), an optical fiber ribbon 1 generally includes a plurality of optical fibers (optical fibers) in which an outer periphery of an optical fiber 2 having an outer diameter of 125 μm is coated with a fiber coating 3 having an outer diameter of 250 μm. In general, a fiber-like (4), which is also referred to as a fiber strand, is formed into a tape shape with a resin coating 5 in a lump.

  Many optical fiber ribbons have been developed which are improved from the general optical fiber ribbon 1 shown in FIG. For example, a plurality of optical fiber strands in which glass fibers are coated with a resin are arranged in a row in close contact in the horizontal direction and arranged in multiple rows in a close contact state shifted by a half pitch in the vertical direction. An optical fiber ribbon that is integrated in (1) is disclosed (see Patent Document 1). Thereby, a plurality of rows of optical fibers arranged in parallel can be stacked in the vertical direction with a minimum core pitch, and when two optical fiber rows are narrowed to a horizontal core pitch to be one row, The longitudinal distance required for bending for alignment can be reduced.

JP 2005-292261 A

  However, in the above-described multi-core optical fiber ribbon, as shown in FIG. 10 (b), it is easy to bend in the axial direction perpendicular to the arrangement direction of the optical fibers, but other directions are possible. It is difficult to bend (particularly with respect to the arrangement direction of the optical fibers) due to the optical fiber core wire and the rigidity of the coating.

  When a multi-fiber optical fiber is provided on a board provided in a communication device, there is a need to align the multi-fiber optical fiber by bending it in an arbitrary direction, but due to the above problems, in the multi-fiber optical fiber ribbon, It is difficult to realize such a requirement. Each of the cores constituting the multi-core type core group that is required to be bent in an arbitrary direction is not limited to an optical fiber, but includes an electric cable, a cable for telecommunications, and a thin coaxial cable. .

  The present invention has been made in view of such problems, and an object of the present invention is to provide a method for weaving a multi-core type core group that can bend the multi-core type group of cords in an arbitrary direction. It is to provide.

  In order to achieve such an object, the invention according to claim 1 is to create a multi-core type core group by weaving M cores (M is an even number of 4 or more) having the same length. The method of weaving a multi-core type core wire group, wherein the tips of the M core wires are aligned and arranged in parallel, and one of the two core wires located at both ends is knitted from the tip portion. Positioned at both ends toward the core located on the same side as the one core wire when viewed from the center, at one of the two core wires positioned in the center at the downstream position Of the core wires positioned at the both ends in order from the outside with respect to the core wire positioned between one of the core wires positioned at the center and one of the core wires positioned at the center and one of the core wires positioned at the center. One side is alternately crossed from the upper side or the lower side and then from the lower side or the upper side, One of the cores positioned is positioned in the center, and the other of the two cores positioned at both ends is placed at a position downstream of the leading end in the weaving direction, Toward the core located on the same side as the other core when viewed from the center, between the other of the lines positioned at both ends and the other of the cores positioned at the center In order from the outside to the core wire positioned at the other side and the other core wire positioned at the center, the other of the core wires positioned at the both ends is respectively from the upper side or the lower side, and then from the lower side or the upper side. The first cross step in which the core wires located at both ends are crossed alternately so that the other core wire is located in the center, and the core wire located in the center one is finally crossed in the first cross step. From the center in the downstream direction of the weaving direction A second cross step that crosses from the upper side or the lower side of the core wire positioned at the top and bottom so that the left and right of the core wire located in the center after the first cross step are switched; The first cross step repeats the first cross step and the second cross step until returning to the order, and in the first cross step, not the position of the wake in the weaving direction from the tip portion, And a first repetition step in which the cross is started at a position downstream of the weaving direction from a position crossed last in the second cross step.

  According to the present invention, it is possible to create a multi-core type wire group in which the lengths of a plurality of core wires are equal, and it is possible to bend the multi-core type wire group in an arbitrary direction.

  According to a second aspect of the present invention, in the multi-core cord group knitting method according to the first aspect of the present invention, the method further includes a second repetitive step of repeating the first repetitive step.

  According to the present invention, it is possible to adjust the length of the multi-core type wire group.

  The invention according to claim 3 is a method of weaving multi-core core groups to create a multi-core core group by weaving N (N is an odd number greater than or equal to 3) cores having the same length. The step of arranging the tips of the N core wires in parallel and arranging them in parallel, and the core wire positioned at one end of the core wire positioned at the center side at a position downstream from the tip portion in the weaving direction. A first cross step of alternately crossing from the upper side or the lower side and then from the lower side or the upper side in order from the outside so that the core wire originally located at one end is located at the center; The core wire located at the other end is located downstream from the position where it was last crossed in the first cross step, and the upper or lower side sequentially from the outer side with respect to the core wire located at the center side in the knitting direction. Next, cross from the lower side or the upper side alternately, and it is originally located at the other end. In a first cross step of repeating the first cross step and the second cross step until returning to the order in which the core wires were initially arranged until the core wire is positioned in the center. In the first cross step, the cross is started not at the position of the wake flow in the weaving direction from the tip portion but at the position of the wake flow in the knitting direction from the position crossed last in the second cross step. And a first iterative step.

  According to the present invention, it is possible to create a multi-core type wire group in which the lengths of a plurality of core wires are equal, and it is possible to bend the multi-core type wire group in an arbitrary direction.

  According to a fourth aspect of the present invention, in the method for braiding a multi-core type core wire group according to the third aspect, the method further comprises a second repetition step for repeating the first repetition step.

  According to the present invention, it is possible to adjust the length of the multi-core type wire group.

  The invention according to claim 5 is a method of weaving a multi-core type core wire group for creating a multi-core type core wire group by weaving two equal-length core wires into the multi-core type core wire group. Aligning the tips of the core wires and arranging them in parallel; and crossing one of the two core wires with the other of the two core wires every predetermined length from the tip portion. It is characterized by that.

  According to the present invention, it is possible to create a multi-core type wire group in which the lengths of the two core wires are equal, it is possible to bend the multi-core type wire group in an arbitrary direction, and It is possible to adjust the length of the mold core group.

  A sixth aspect of the present invention is the multi-core type of weaving method according to any one of the first to fifth aspects, wherein the core is an optical fiber.

  According to this invention, the multi-fiber optical fiber can be applied as an optical cord for optical communication by making the individual optical fiber core wires constituting the multi-fiber optical fiber have the same length.

  According to a seventh aspect of the present invention, in the method for braiding a multi-core type core wire group according to the sixth aspect, when the optical fiber core wire is knitted, a radius of curvature of a bent portion of each of the optical fiber core wires is set. It is characterized by being in a range that does not cause bending loss.

  According to the present invention, stable transmission can be performed even when a multi-core optical fiber is bent.

  The invention according to claim 8 is the method of braiding a multi-core type core wire group according to claim 6 or 7, wherein the optical fiber core wire includes a double core optical fiber, a trench type optical fiber, and a photonic crystal fiber. Or any one of the above.

  According to the present invention, the strength when the number of optical fibers is increased can be increased, and stable transmission can be performed even when the multi-core optical fibers are bent.

  The invention according to claim 9 is the method of braiding a multi-core type core wire group according to any one of claims 1 to 5, wherein the core wire includes an electric cable, a telecommunication cable, and a thin wire. It is one of the coaxial cables.

  According to the present invention, it is possible to create a multi-core type wire group in which the lengths of a plurality of core wires are equal, and it is possible to bend the multi-core type wire group in an arbitrary direction.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings described below, components having the same function are denoted by the same reference numerals, and repeated description thereof is omitted.

  In an embodiment of the present invention, a bendable core wire such as an optical fiber, a lead wire, an electric wiring cable, or a fine coaxial cable is knitted by a braiding method characteristic of the present invention as described later.

  For example, when an optical fiber is used as the core wire, the radius of curvature of the bent portion of each optical fiber core wire is important in the braided optical fiber.

  That is, an optical fiber has a structure in which a core having a relatively high refractive index is covered with a clad having a relatively low refractive index, unlike a member for transmitting an electric current such as a normal lead wire. The optical signal is transmitted while totally reflecting the light. When an optical fiber having such a structure is bent, the effective refractive index of the cladding outside the bend increases, and when the radius of curvature decreases (when the bending becomes tight), the increased refractive index of the cladding is higher than the refractive index of the core. There is a case. In this case, light guided through the core is radiated to the clad and induces bending loss.

  Therefore, in one embodiment of the present invention, the optical fiber core wire is bent and knitted. When the optical fiber is knitted, it is preferable that the curvature radius of the bent portion is in a range in which no bending loss occurs. .

  By using the braiding method according to an embodiment of the present invention, the optical fiber can be bent with a radius of curvature larger than the radius of curvature that gives the bending loss in the optical fiber. , Bending loss can be reduced or prevented.

  In addition, although there is no restriction | limiting in the optical fiber used in this embodiment, Since the curvature radius which gives the said bending loss can be made small by using the optical fiber which is mentioned later, versatility can be improved more.

  As described above, it is preferable to use an optical fiber having a small radius of curvature that gives a bending loss. However, depending on the use of a multi-core optical fiber manufactured according to the above-described braiding method (for example, when only a short length is used) ), Even if some bending loss occurs, there is no problem.

(First optical fiber)
FIG. 1 is an explanatory diagram of a double core optical fiber 100 which is a first optical fiber suitable for use in an embodiment of the present invention. FIG. 1A shows a refractive index profile of the double core optical fiber, and FIG. 1B shows a cross-sectional structure of the double core optical fiber having the refractive index profile of FIG. Here, the double-core optical fiber includes a single mode transmission core and a multimode transmission core in one optical fiber at the same time, and the single mode signal light and the multimode signal light are transmitted by the same optical fiber. An optical fiber that enables transmission.

  In FIG. 1B, a core 111 as a first material for single mode transmission is provided at the center, and a first clad 121 as a second material and a third material are sequentially formed outside the core 111. The second clad 131, the third clad 141 as the fourth material, and the fourth clad 151 made of a polymer resin are provided. For the core 111 and the first to third claddings, materials usually used for optical fibers such as quartz glass, polymers, and organic substances such as acrylic can be used.

  The diameter of the double core optical fiber is 250 μm or 900 μm. In the double core optical fiber, the core 111 is quartz to which one of Ge, P, Sn, and B elements is added. The first cladding 121 is pure quartz. Further, the second clad 131 and the third clad 141 are quartz to which different amounts of F element are added in order to lower the refractive index.

  Note that additives (for example, Ge, P, Sn, and B elements) added to the core 111 are selected so as to increase the refractive index of a base material such as quartz.

  Further, although the F element is added to quartz for the second cladding 131 and the third cladding 141, the additive is not limited to this. For example, any additive that can lower the refractive index of quartz, such as B element, may be used as an additive to be added to the base material of the second cladding 131 and the third cladding 141, such as quartz. . In the double core optical fiber, the refractive index can be further reduced by adding the B element to the third cladding 141 in addition to the F element.

  In FIG. 1A, reference numeral 112 denotes the refractive index of the core 111, reference numeral 122 denotes the refractive index of the first cladding 121, reference numeral 132 denotes the refractive index of the second cladding 131, and reference numeral 142 denotes the third cladding. 141 is a refractive index of the fourth cladding 151. As can be seen from FIG. 1A, the refractive index 122 of the first cladding 121 is smaller than the refractive index 112 of the core 111, the refractive index 132 of the second cladding 131 is smaller than the refractive index 122 of the first cladding 121, The refractive index 142 of the third cladding 141 is smaller than the refractive index 132 of the second cladding 131. In addition, the refractive index 152 of the fourth cladding 151 is higher than the refractive index 142 of the third cladding 141.

  In such a configuration, the core 111 functions as a core for single mode transmission, and the core 111 and the first cladding 121 function as a core for multimode transmission. In the double-core optical fiber, the optical signal wavelength for single mode transmission (the wavelength of the optical signal that excites the specified mode of the core 111 and transmits the single mode) is changed to the C-Band band (1530 nm to 1560 nm) or the L-Band band ( 1570 nm to 1610 nm), or alternatively, any of the 1300 nm band can be designed. Further, the mode field diameter can be set to 7.0 to 10.0 μm. That is, the mode field diameter of the above-mentioned specified mode can be set to 7.0 to 10.0 μm.

  In the double-core optical fiber, in the multimode signal light having a wavelength of 850 nm, an electric field strength distribution is formed over the core 111, the first cladding 121, and the second cladding 131, and the step index type multimode fiber having a wavelength of 850 nm or a wavelength of 850 nm. It is designed to be equivalent to the aperture ratio of band graded index type multimode fiber. The optical signal wavelength for multimode transmission (the wavelength of the optical signal for multimode transmission by exciting the core for multimode transmission including the core 111 and the first cladding 121) is designed to be 850 nm. Furthermore, the diameter of the core for multimode transmission, that is, the diameter of the first cladding 121 can be set to 50 μm or 62.5 μm.

  In the double core optical fiber, the diameter of the first clad 121 that defines the diameter of the core for multimode transmission is set to be the same as or substantially the same as the diameter of the optical fiber for multimode transmission, Since the aperture ratio of the optical fiber is set, an optical fiber for multimode transmission (for example, a multimode optical fiber having an optical signal wavelength of 850 nm as introduced in a LAN (Local Area Network)) and a low loss are provided. The multimode signal light can be transmitted with low loss.

  Further, in the double-core optical fiber, the core 111 included in the multi-mode transmission core also functions as a single-mode transmission core. Mode signal light can be transmitted.

  That is, both the single-mode signal light and the multi-mode signal light, and one each can be transmitted through the same optical fiber.

  FIG. 3 shows a refractive index profile when the double core optical fiber is bent in the shape shown in FIG. In FIG. 2, reference numeral 21 denotes a center of curvature, reference numeral 22 denotes a radius of curvature, reference numeral 23 denotes an outer peripheral side of the optical fiber when the optical fiber is bent, and reference numeral 24 denotes an optical fiber when the optical fiber is bent. It is the inner circumference side. In FIG. 3, reference numeral 175 denotes the maximum value of the refractive index of the core 111 when the radius of curvature R is.

  At this time, the refractive index on the outer periphery side of the second cladding 121 (on the right side in FIG. 3) becomes higher, but the refractive index 132 of the second cladding 131 is made smaller than the refractive index 122 of the first cladding 121, and further the third cladding. Since the refractive index 142 of 141 is set to be smaller than the refractive index 132, the refractive index of the core 111 can be obtained even with a radius of curvature in which a region having a refractive index higher than that of the core is generated in the conventional double clad fiber. Generation of a region having a refractive index higher than 112 can be eliminated. Therefore, the deterioration of the transmission characteristics of the optical signal transmitted through the core is not given, and no increase in error at the time of demodulation at the optical signal receiving end that may occur when a double clad fiber is used. That is, when the optical fiber is bent, a part of the single mode signal light leaking from the core 111 is trapped in the first clad 121, the second clad 131, and the third clad 141, or reflected from each of them and returned to the core 111. Without reaching the fourth cladding 151, it can be absorbed. Therefore, when the optical fiber is bent, stable single mode transmission and further multimode transmission can be performed simultaneously.

  In addition, by reducing the radius of curvature R (tightening the bend), there may be a region where the refractive indexes 132 and 142 are larger than the maximum value 175. Even if a region larger than the maximum value 175 is generated in this way, the region is smaller than the region generated in the conventional double clad fiber when bent at the same curvature radius R. Accordingly, it is possible to reduce multimode transmission due to the radiation mode of the single mode signal light guided through the core 111 when the optical fiber is bent.

  Thus, in the double-core optical fiber, in the conventional double-clad fiber, in the radius of curvature R that causes a region that is higher than the refractive index of the core, even if the region is eliminated or the region is generated, Since the area can be made smaller than before, multimode transmission of signal light guided through the core can be reduced.

  In the double core optical fiber, the second cladding 131 having a refractive index 132 lower than the refractive index 122 has a function of confining the multimode signal light in the core for multimode transmission, and further, When bent, it has a function of reducing multimode transmission of single-mode signal light guided through the core 111.

  Further, the third cladding 141 having a refractive index 142 lower than the refractive index 132 has a function of confining the multimode signal light in the core for multimode transmission more satisfactorily. In other words, the third clad 141 with a low refractive index to which the F element is added plays a role of further reducing the multimode signal light being guided to the fourth clad 151 which is a coating formed of a polymer resin. .

(Second optical fiber)
FIG. 4 is an explanatory view of a trench type optical fiber which is a second optical fiber suitable for use in the embodiment of the present invention. 4A is a cross-sectional structure diagram of the trench type optical fiber, and FIG. 4B is a refractive index distribution diagram of the trench type optical fiber of FIG.

  In the trench type optical fiber shown in FIG. 4A, a material (low refractive index material) 43 having a low refractive index at a position 20 μm away from the center of the single mode core 41 surrounded by the quartz glass 42. Is arranged.

  In FIG. 4B, reference numeral 44 is the refractive index of the core 41, reference numeral 45 is the refractive index of the low refractive index material 43, and reference numeral 46 is the refractive index of the quartz glass 42. In the trench type optical fiber, the low refractive index material 43 arranged 20 μm away from the core 41 stabilizes the confinement of the electric field strength distribution when the optical fiber body is bent.

  An optical fiber suitable for use in the embodiment of the present invention may be a photonic crystal fiber (not shown) having a plurality of holes around the core.

  Here, in this specification, in an optical fiber, the maximum radius of curvature that does not give bending loss is defined as the maximum allowable radius of curvature. The maximum allowable radius of curvature of an optical fiber for single mode signal light transmission is usually 30 mm, the maximum allowable radius of curvature of an optical fiber for multimode signal light transmission is usually 15 mm, and the maximum allowable radius of curvature of a double clad fiber is usually normal Although it is 15 mm, in the double core optical fiber, the radius of curvature can be set to the same value in consideration of excess loss due to bending of the optical fiber, and it can be further bent and used with a radius of curvature of up to about 5 mm. . Moreover, the maximum allowable curvature radius of the trench type optical fiber is 7.5 to 10 mm, and the maximum allowable curvature radius of the photonic crystal fiber is 7.5 to 10 mm.

(First embodiment)
In the first embodiment, a mode in which an optical fiber is used as a core wire to be knitted will be described.
FIG. 5 is a schematic view continuously showing the method of braiding a multi-core optical fiber according to the first embodiment of the present invention. The present embodiment is a method of weaving a multi-core optical fiber using four optical fiber cores, but the number of optical fiber cores constituting the multi-core optical fiber is not limited to four, and any even number A multi-core optical fiber can be produced using a single optical fiber.

  In addition, since it has the function and effect mentioned above, it is preferable to use a double core optical fiber, a trench type optical fiber, or a photonic crystal fiber as an optical fiber core wire. However, the optical fiber core wire that can be used in the present embodiment is not limited to these, and includes a conventional single-mode signal light transmission optical fiber, a multi-mode signal light transmission optical fiber, and a double-clad fiber. It may be used.

  The thickness of the optical fiber core shown in the figure does not represent the difference in the thickness of the actual optical fiber core wire, but to show that each is a different optical fiber core wire, the thickness of the optical fiber core wire is changed. Yes. The scale is not accurately represented.

  First, the tips of four equal-length optical fiber cores 51, 52, 53, 54 are aligned and arranged in parallel (S501). This figure is the figure which looked at the optical fiber core wires 51-54 from the upper side, and is arrange | positioned in order of 51, 52, 53, 54 from the left initially.

Next, the optical fiber cores 51 and 54 positioned at both ends are light viewed from the center of the two optical fiber cores positioned at the center at a position of a predetermined length l ₁ from the front end to the bottom of the drawing. The optical fiber cores 51 and 54 are crossed from the upper side with the optical fiber core wires (that is, the optical fiber core wires 52 and 53, respectively) on the same side as each of the fiber core wires 51 and 54 so that the optical fiber core wires 51 and 54 are located in the center. (S502). In the state after S502, the optical fiber core wires are arranged in a balanced manner in the order of 52, 51, 54, 53 from the left.

Next, the optical fiber core wire 51 located at the center left is crossed from the upper side with the optical fiber core wire 54 located at the center right at the position of the length l ₁ from the position crossed in S502 (not shown). (S503). In the state after S503, the optical fiber core wires are arranged in a balanced manner in the order of 52, 54, 51, 53 from the left.

Next, the optical fiber cores 52 and 53 positioned at both ends are positioned at a length l ₁ below the drawing from the position (not shown) crossed in S503, of the two optical fiber cores positioned at the center respectively. When viewed from the center, the optical fiber core wires 52 and 53 are crossed from the upper side with the optical fiber core wires on the same side as the optical fiber core wires 52 and 53 (that is, the optical fiber core wires 54 and 51, respectively). (S504). In the state after S504, the optical fiber core wires are arranged in a balanced manner in the order of 54, 52, 53, 51 from the left.

Next, the optical fiber core wire 52 positioned at the center left is crossed from the upper side with the optical fiber core wire 53 positioned at the center right at the position of the length l ₁ below the drawing from the position (not shown) crossed at S504. (S505). In the state after S505, the optical fiber core wires are arranged in a balanced manner in the order of 54, 53, 52, 51 from the left.

Next, optical fiber cores 54 and 51 located at both ends are located at a position of length l ₁ from the position (not shown) crossed in S505, and the center of the two optical fiber cores positioned at the center respectively. When viewed from the center, the optical fiber core wires 54 and 51 are crossed from the upper side with the optical fiber core wires on the same side as the optical fiber core wires 54 and 51 (that is, the optical fiber core wires 53 and 52, respectively). (S506). In the state after S506, the optical fiber core wires are arranged in a balanced manner in the order of 53, 54, 51, 52 from the left.

Next, the optical fiber core wire 54 positioned at the center left is crossed from the upper side with the optical fiber core wire 51 positioned at the center right at a position of length l ₁ from the position crossed in S506 (not shown). (S507). In the state after S507, the optical fiber core wires are arranged in a balanced manner in the order of 53, 51, 54, 52 from the left.

Next, the optical fiber cores 53 and 52 located at both ends are positioned at a length l ₁ from the position (not shown) crossed in S507, and the center of the two optical fiber cores positioned at the center respectively. When viewed from the center, the optical fiber core wires 53 and 52 are crossed from the upper side with the optical fiber core wires on the same side as the optical fiber core wires 53 and 52 (that is, the optical fiber core wires 51 and 54, respectively). (S508). In the state after S508, the optical fiber core wires are arranged in a balanced manner in the order of 51, 53, 52, and 54 from the left.

Next, the optical fiber core wire 53 positioned at the center left is crossed from the upper side with the optical fiber core wire 52 positioned at the center right from the position (not shown) crossed at S508 at a position of length l ₁ downward from the drawing. (S509). In the state after S508, the optical fiber core wires are arranged in a balanced manner in the order of 51, 52, 53, 54 from the left, and thereafter, S502 to S509 are repeated (however, for S502, “from the tip to the bottom of the drawing” "The position of the predetermined length l ₁ " is read as "the position of the length l ₁ downward from the position crossed in S508 (not shown)").

  In the present embodiment, the optical fiber cores on the crossing side are all crossed from the upper side, but may all be crossed from the lower side.

  In the multi-core optical fiber produced by the method of the present embodiment, the individual optical fiber cores constituting the multi-core optical fiber can be made equal in length. Thereby, the present multi-fiber optical fiber can be applied as an optical cord for optical communication. Moreover, this multi-fiber optical fiber can be used for wiring on a board provided in a communication device, for example, with a length of 50 cm to 1 m.

  This braiding method can also be applied to a case where a multi-fiber optical fiber is formed using M (M is an even number of 4 or more) optical fiber core wires. Next, the above case will be described.

  First, the tips of M optical fiber core wires each having the same length are aligned and arranged in parallel.

  Then, one of the two optical fiber cores positioned at both ends is one of the two optical fiber cores positioned at the center at the position downstream of the leading end of the braided direction, When viewed from the center, toward one of the optical fiber cores located on the same side as the one optical fiber core, between one of the optical fiber cores positioned at both ends and one of the optical fiber cores positioned at the center One of the optical fiber cores located at the both ends is sequentially arranged from the upper side (or the lower side) in order from the outside with respect to the optical fiber core wire located at the center and one of the optical fiber core wires located at the center. Next, crossing is alternately performed from the lower side (or the upper side) so that one of the optical fiber cores positioned at both ends is positioned at the center.

  At the same time or subsequently, the other of the two optical fiber cores positioned at both ends is connected to the other of the two optical fiber cores positioned in the center at a position downstream of the leading end in the weaving direction. An optical fiber core located at the other and the center of the optical fiber cores located at both ends toward the optical fiber core wire located on the same side as the other optical fiber core as viewed from the center The other one of the optical fiber cores positioned at both ends in order from the outside with respect to the optical fiber core wire positioned between the other optical fiber core wires and the other optical fiber core wire positioned at the center, Cross each other alternately from the upper side (or lower side) and then from the lower side (or upper side) so that the other of the optical fiber cores positioned at both ends is positioned at the center (optical fibers positioned at both ends). Heart By cross it to be positioned in the middle it will be referred to as the first cross step as). In this state, the optical fiber cores are arranged in a balanced manner.

  Next, the optical fiber core located in one of the centers is positioned upstream of (or below) the optical fiber core positioned in the other of the center at the downstream position of the weaving direction from the position where it was last crossed in the first cross step. And the left and right optical fiber cores located at the center after the first cross step are switched (this will be referred to as a second cross step). In this state, the optical fiber cores are arranged in a balanced manner.

  Next, by repeating these two steps a plurality of times (however, at the time of repetition, the “position of the wake in the weaving direction from the tip portion” in the first cross step was crossed last in the second cross step) It is read as “the position of the wake in the weaving direction from the position”), and first returns to the positional relationship in which the optical fiber cores are aligned. Iterating until returning to the initial positional relationship is referred to as a first iterative step. By repeating the first repetition step a plurality of times (referred to as the second repetition step), the length of the multi-core optical fiber in which the optical fiber cores are equal in length can be adjusted. it can.

  This weaving method can be applied even when two optical fiber cores of equal length are used. When two equal-length optical fiber cores are used, it is only necessary to repeat a plurality of times of crossing from the front end portion every predetermined length.

  In the present specification, the “knitting direction” is a direction opposite to the tip portion and a direction in which the core wire is knitted. Therefore, “the position of the wake in the weaving direction” is a position away from a certain position along the weaving direction by an arbitrary distance.

(Second Embodiment)
Also in the second embodiment, a mode in which an optical fiber is used as a core wire to be knitted will be described.
FIG. 6 and FIG. 7 are schematic views continuously showing a method of weaving a multi-core optical fiber according to the second embodiment of the present invention. The present embodiment is a multi-fiber optical fiber weaving method using five optical fiber cores, but the number of optical fiber cores constituting the multi-fiber optical fiber is not limited to five, and any odd number A multi-core optical fiber can be produced using a single optical fiber (other than one).

  In addition, since it has the function and effect mentioned above, it is preferable to use a double core optical fiber, a trench type optical fiber, or a photonic crystal fiber as an optical fiber core wire. However, the optical fiber core wire that can be used in the present embodiment is not limited to these, for example, a conventional single-mode signal light transmission optical fiber, a multi-mode signal light transmission optical fiber, and a double clad. A fiber may be used.

  The thickness of the optical fiber core shown in the figure does not represent the difference in the thickness of the actual optical fiber core wire, but to show that each is a different optical fiber core wire, the thickness of the optical fiber core wire is changed. Yes. The scale is not accurately represented.

  First, the tips of five equal-length optical fiber cores 61, 62, 63, 64, 65 are aligned and arranged in parallel (FIG. 6; S601). This figure is the figure which looked at the optical fiber core wires 61-65 from the upper side, and is arrange | positioned in order of 61, 62, 63, 64, 65 from the left initially.

Then, the optical fiber cores 61 located at the left end, at a position of a predetermined length l ₂ in the drawing downward from the tip, are crossed from the optical fiber 62 and the upper is located next further optical fiber 62 Is crossed from the lower side with the optical fiber core wire 63 positioned next to the optical fiber core wire 61 so that the optical fiber core wire 61 is at the center position (FIG. 6; S602). In the state after S602, the optical fiber core wires are arranged in a balanced manner in the order of 62, 63, 61, 64, 65 from the left.

Next, the optical fiber core wire 65 positioned at the right end is crossed from the upper side with the adjacent optical fiber core wire 64 at the position of the length l ₂ below the drawing from the position (not shown) last crossed in S602. Further, the optical fiber core wire 63 is crossed from the lower side with the optical fiber core wire 63 located next to the optical fiber core wire 64 so that the optical fiber core wire 65 is at the center position (FIG. 6; S603). In the state after S603, the optical fiber core wires are arranged in a balanced manner in the order of 62, 63, 61, 64, 65 from the left.

Next, the optical fiber core wire 62 positioned at the left end is crossed from the upper side with the adjacent optical fiber core wire 63 at a position of length l ₂ below the drawing from the position (not shown) last crossed in S603. Further, the optical fiber core wire 65 is crossed from the lower side with the optical fiber core wire 65 located next to the optical fiber core wire 63 so that the optical fiber core wire 62 is at the center position (FIG. 6; S604). In the state after S604, the optical fiber core wires are arranged in a balanced manner in the order of 63, 65, 62, 61, 64 from the left.

Next, the optical fiber core wire 64 positioned at the right end is crossed from the upper side with the adjacent optical fiber core wire 61 at the position of the length l ₂ below the drawing from the position (not shown) last crossed in S604. Further, the optical fiber core wire 62 is crossed from the lower side with the optical fiber core wire 62 positioned next to the optical fiber core wire 61 so that the optical fiber core wire 64 is at the center position (FIG. 6; S605). In the state after S605, the optical fiber core wires are arranged in a balanced manner in the order of 63, 65, 64, 62, 61 from the left.

Next, the optical fiber core 63 positioned at the left end is crossed from the upper side with the adjacent optical fiber core 65 at the position of the length l ₂ below the drawing from the position (not shown) last crossed in S605. Furthermore, the optical fiber core wire 64 is crossed from the lower side with the optical fiber core wire 64 located next to the optical fiber core wire 65 so that the optical fiber core wire 63 is at the center position (FIG. 6; S606). In the state after S606, the optical fiber core wires are arranged in a balanced manner in the order of 65, 64, 63, 62, 61 from the left.

Next, the optical fiber core 61 positioned at the right end is crossed from the upper side with the adjacent optical fiber core 62 at a position of length l ₂ below the drawing from the position (not shown) last crossed in S606. Then, the optical fiber core wire 61 is crossed from the lower side with the optical fiber core wire 63 positioned next to the optical fiber core wire 62 so that the optical fiber core wire 61 is at the center position (FIG. 7; S607). In the state after S607, the optical fiber core wires are arranged in a balanced manner in the order of 65, 64, 61, 63, 62 from the left.

Next, the optical fiber core wire 65 positioned at the left end is crossed from the upper side with the adjacent optical fiber core wire 64 at a position of length l ₂ below the drawing from the position (not shown) last crossed in S607. Further, the optical fiber core wire 61 is crossed from the lower side with the optical fiber core wire 61 located next to the optical fiber core wire 64 so that the optical fiber core wire 65 is at the center position (FIG. 7; S608). In the state after S608, the optical fiber core wires are arranged in a balanced manner in the order of 64, 61, 65, 63, 62 from the left.

Next, the optical fiber core wire 62 positioned at the right end is crossed from the upper side with the adjacent optical fiber core wire 63 at the position of the length l ₂ below the drawing from the position (not shown) last crossed in S608. Further, the optical fiber core wire 65 is crossed from the lower side with the optical fiber core wire 65 located next to the optical fiber core wire 63 so that the optical fiber core wire 62 is at the center position (FIG. 7; S609). In the state after S609, the optical fiber core wires are arranged in a balanced manner in the order of 64, 61, 62, 65, 63 from the left.

Next, the optical fiber core wire 64 located at the left end is crossed from the upper side with the adjacent optical fiber core wire 61 at a position of length l ₂ downward from the position (not shown) where it was finally crossed in S609. Further, the optical fiber core wire 62 is crossed from the lower side with the optical fiber core wire 62 located next to the optical fiber core wire 61 so that the optical fiber core wire 64 is at the center position (FIG. 7; S610). In the state after S610, the optical fiber core wires are arranged in a balanced manner in the order of 61, 62, 64, 65, 63 from the left.

Next, the optical fiber core wire 63 positioned at the right end is crossed from the upper side with the adjacent optical fiber core wire 65 at a position of length l ₂ below the drawing from the position (not shown) that was crossed last in S610. Furthermore, the optical fiber core wire 64 is crossed from the lower side with the optical fiber core wire 64 located next to the optical fiber core wire 65 so that the optical fiber core wire 63 is at the center position (FIG. 7; S611). In the state after S611, the optical fiber cores are arranged and arranged in a balanced manner in the order of 61, 62, 63, 64, 65 from the left, and thereafter, S602 to S611 are repeated (however, with respect to S602, “tip” "The position of the predetermined length l ₂ below the drawing" is read as "the position of the length l ₂ below the drawing from the position crossed in S611 (not shown)").

  In this embodiment, the optical fiber core 61 at the left end is started by crossing, but the optical fiber core 65 at the right end may be started by crossing. In this embodiment, the optical fiber cores at both ends are connected to the upper side, the lower side, the upper side, the lower side,. . . Are crossed alternately in this order, but the optical fiber cores at both ends are placed on the lower side, upper side, lower side, upper side,. . . You may make it cross alternately in order.

  In the multi-core optical fiber produced by the method of the present embodiment, the individual optical fiber cores constituting the multi-core optical fiber can be made equal in length. Thereby, the present multi-fiber optical fiber can be applied as an optical cord for optical communication. Moreover, this multi-fiber optical fiber can be used for wiring on a board provided in a communication device, for example, with a length of 50 cm to 1 m.

  This braiding method can also be applied to a case where a multi-core optical fiber is formed using N optical fibers (N is an odd number of 3 or more). Next, the above case will be described.

  First, the tips of N optical fiber cores each having the same length are aligned and arranged in parallel.

  Next, the optical fiber core wire located at one end is moved from the top side (or lower side) in order from the outside to the optical fiber core wire located at the center side at the downstream position from the tip portion in the weaving direction. Are alternately crossed from the lower side (or the upper side) so that the optical fiber core originally positioned at one end is positioned at the center (this will be referred to as a first cross step). In this state, the optical fiber cores are arranged in a balanced manner.

  Next, the optical fiber core wire positioned at the other end is sequentially moved from the outside with respect to the optical fiber core wire positioned at the center side at the downstream position of the weaving direction from the position where the optical fiber core wire is finally crossed in the first cross step. , Alternately from the top (when first crossed from the top in the first cross step) (or from the bottom; first crossed from the top in the first cross step) and then from the bottom (or top) The optical fiber core wire originally positioned at the other end is positioned at the center (this is called a second cross step). In this state, the optical fiber cores are arranged in a balanced manner.

  Next, by repeating these two steps a plurality of times (however, at the time of repetition, the “position of the wake in the weaving direction from the tip portion” in the first cross step was crossed last in the second cross step) It is read as “the position of the wake in the weaving direction from the position”), and first returns to the positional relationship in which the optical fiber cores are aligned. However, when a multi-core optical fiber is created using three optical fiber cores, it is only necessary to repeatedly cross the optical fiber core wire at the center once every arbitrary distance. Iterating until returning to the initial positional relationship is referred to as a first iterative step. By repeating the first repetition step a plurality of times (referred to as the second repetition step), the length of the multi-core optical fiber in which the optical fiber cores are equal in length can be adjusted. it can.

The predetermined lengths l ₁ and l ₂ described above are curvature radii that cause bending loss to the optical fiber cores constituting the multi-core optical fiber according to the number of optical fiber cores constituting the multi-fiber optical fiber. It is preferable that the curvature radius generated by weaving the multi-core optical fiber is larger than (maximum allowable curvature radius).

In the braiding method according to the embodiment of the present invention, the predetermined lengths l ₁ and l ₂ may not be determined. In such a case, when the braiding is finished, the multi-core optical fiber is pulled and tightened to produce a multi-core optical fiber in which the front end portion and the rear end portion of each optical fiber core wire are aligned.

  FIG. 8 is an explanatory view showing a multi-core optical fiber produced according to an embodiment of the present invention, and (a) is a multi-core optical fiber 81 composed of four optical fiber core wires, and (b) ) Is a multi-core optical fiber 82 composed of five optical fiber core wires.

  Moreover, FIG. 9 is explanatory drawing which shows the multi-core optical fiber 91 produced according to the braiding method different from this invention. In this method, when the optical fiber core wire located at one end is brought to the other end, the optical fiber core wire located at the one end is crossed with all the optical fiber core wires other than itself. From the optical fiber core wire originally located at one end to the other end toward the other end, with respect to an optical fiber core wire other than the optical fiber core wire originally located at one end It is made to cross so that it may shift gradually one by one.

  Now, what is important in the present invention is that it is possible to bend an optical fiber or the like in an arbitrary direction by weaving a core, and even if the knitted core is folded, a bent portion or the like In order to prevent the braided cord from sagging as much as possible.

  It is desired to arrange a multi-fiber optical fiber so as to be sewn in a circuit of 1 m × 2 m, for example, due to the present advanced information and information capacity. In such a circuit, there are a large number of pins or the like, and when the multi-core optical fiber is arranged so as to be sewn as described above, if a part of the core wire is slack, it is caught by the pins, The trapped core wire may be unwound from the multi-core optical fiber. Therefore, it is useful to weave an optical fiber in consideration of bending the multi-core optical fiber in an arbitrary direction, but in consideration of arranging the multi-fiber optical fiber by dragging, the light after being knitted is used. It is important to reduce the slack of the fiber core.

  Therefore, in the embodiment of the present invention, in order to knit so as to be able to bend in an arbitrary direction while reducing the slack, as described in the first and second embodiments, a plurality of core wires are used. The first core wire arranged at one end is brought to the center while vertically crossing the core wire between the end and the center.

  In the multi-core optical fiber 91 knitted as shown in FIG. 9, when knitting the core wire, the second core wire arranged at one end of the plurality of core wires is replaced with the one of the one core wires. While the core wire between one end and the other end is crossed up and down, it is knitted so as to come to the other end. By braiding the other core wires in this way, the second core wire is moved from the one end to the other end along the longitudinal direction of the multi-core optical fiber, and then shifted one by one thereafter. , Will be knitted back to one end. The distance along the longitudinal direction from the one end to the end again is referred to as a pitch (indicated by symbol P in FIGS. 8 and 9).

That is, in the weaving method of the multi-core optical fiber 91 shown in FIG. 9, when the second core wire is moved from one end to the other end at the pitch P92, all the cores other than the second core wire are used. A region (first cross region) 93 that crosses the line and a region (first cross region) that gradually deviates one by one from the other end toward one end with respect to the cores other than the second core 2 cross regions) 94. Since the length p ₁ along the longitudinal direction of the first cross region 93 crosses all the core wires other than the second core wire, the length p ₁ along the longitudinal direction of the second cross region 94 It is considerably shorter than p ₂ (P = p ₁ + p ₂ ). Therefore, the first cross region 93 and the second cross region 94 have a completely asymmetric shape, and the radius of curvature of each of the optical fiber cores differs depending on the bending location.

Further, the first cross region 93 is crossed with all the core wires other than the second core wire, and the second cross region 94 is gradually crossed by shifting one by one. Since the radius of curvature of the second core wire becomes smaller (the curve becomes tighter) and must gradually shift when returning from the other end to the other end, the length p ₂ becomes longer and the pitch P92 itself is also increased. become longer. Therefore, since the pitch P92 is long, when the multi-core optical fiber 91 is routed, the optical fiber core wire is liable to be loosened.

  On the other hand, in the embodiment of the present invention, the first core wire disposed at one end is disposed at the center while vertically crossing the core wire between the one end and the center. By making the core wires other than the first core wire cross in the same manner, the first core wire is moved to the other end (first moving cross step). Next, the first core wire that has moved to the other end is again placed in the center while the core wire between the other end and the center is vertically crossed, and the core wires other than the first core wire are arranged. Is also crossed similarly (second moving cross step). As a result, the first core wire moves again to one end.

As described above, in the embodiment of the present invention, the first moving cross step and the second moving cross step are performed in the same manner. Therefore, in the pitches P83 and 84, from one end to the longitudinal direction of the multi-core optical fiber. The distance p ₃ to the other end along the other side and the distance p ₄ (P = p ₃ + p ₄ ) from the other end to the one end along the longitudinal direction of the multi-core optical fiber can be made to substantially coincide with each other. it can. Therefore, variation in the radius of curvature at the bent portion can be suppressed.

  Further, the region 85 (87) for moving the first core wire from one end to the other end and the region 86 (88) for moving the first core wire from one end to the other end can be made closer to symmetry, and the pitch Since P83, 84 can be made small, even if the multi-core optical fibers 81, 82 are routed, the slack of the optical fiber core wire can be suppressed, and a multi-fiber optical fiber that is resistant to routing can be realized.

(Other embodiments)
The essence of the present invention is to reduce the slack of each core wire even if it is arranged so as to be sewn while allowing it to be bent in an arbitrary direction by weaving the core wire group. Therefore, the core wire is not limited to an optical fiber, but can be applied to an electric cable, a cable for telecommunications, a thin coaxial cable, and the like.

  As described above, according to the braiding method of the present invention, it is possible to bend a braided core wire group composed of a plurality of equal-length core wires in an arbitrary direction.

  If an optical fiber core wire is used as the core wire to be knitted, according to the braiding method of the present invention, the optical fiber core wires constituting the multi-core optical fiber can be made equal in length. Therefore, it is possible to produce a multi-core optical fiber that can bend the multi-core optical fiber in an arbitrary direction.

  Further, by using a double core optical fiber, a trench type optical fiber, or a photonic crystal fiber as an optical fiber core wire constituting the multi-core optical fiber, the strength when multi-core is increased, Even when the fiber is bent, stable transmission can be performed.

  Further, when the multi-core optical fiber according to the embodiment of the present invention is used, each optical fiber core wire is bent and three-dimensionally woven while changing the relative position of each optical fiber. Replacement can be easily performed. That is, for each of the optical fiber cores, the position of each other optical fiber core wire differs depending on the position of the multi-fiber optical fiber, so the multi-fiber optical fiber is cut at a position where the desired channel arrangement is obtained. Thus, channel switching can be easily performed.

  Furthermore, since the multi-core optical fiber according to the embodiment of the present invention is knitted, it is possible to prevent a predetermined number of optical fiber cores from being pulled out from a plurality of optical fiber cores constituting the multi-fiber optical fiber. Can do.

(A) is a refractive index profile of the double core optical fiber suitable for use in the embodiment of the present invention, and (b) is a cross-sectional structure diagram of the double core optical fiber having the refractive index profile of (a). It is explanatory drawing in the case of bending an optical fiber centering on one point which is a curvature radius R. 3 is a refractive index profile that is changed when a double-core optical fiber suitable for use in an embodiment of the present invention is bent at a curvature radius R. FIG. (A) is a sectional view of a trench type optical fiber suitable for use in the embodiment of the present invention, and (b) is a refractive index distribution diagram of the trench type optical fiber of (a). It is the schematic which shows continuously the weaving method of the multi-core optical fiber which concerns on the 1st Embodiment of this invention. It is the schematic which shows continuously the braiding method of the multi-core optical fiber which concerns on the 2nd Embodiment of this invention. It is the schematic which shows continuously the braiding method of the multi-core optical fiber which concerns on the 2nd Embodiment of this invention. It is explanatory drawing which shows the multi-core optical fiber produced according to embodiment of this invention, (a) is a multi-core optical fiber comprised from four optical fiber core wires, (b) is five It is a multi-core optical fiber composed of optical fiber core wires. It is explanatory drawing which shows the multi-core optical fiber produced according to the weaving method different from this invention. It is explanatory drawing which shows the optical fiber ribbon of a prior art, (a) is a cross-sectional view of an optical fiber ribbon, (b) is a top view of an optical fiber ribbon.

Explanation of symbols

100 Double-core optical fiber 111 Core 112 Core refractive index 121 First clad 122 First clad refractive index 131 Second clad 132 Second clad refractive index 141 Third clad 142 Third clad refractive index 151 Fourth clad 152 First Refractive index of 4 clad 175 Maximum value of refractive index of core at radius of curvature R 41 Core 42 Quartz glass 43 Low refractive index material 44 Core refractive index 45 Refractive index of low refractive index material 46 Refractive index of quartz glass 51, 52, 53, 54 Optical fiber core wire 61, 62, 63, 64, 65 Optical fiber core wire 81, 82 Braided multi-core optical fiber

Claims (9)

A method of weaving multi-core cord groups for creating a multi-core cord group by weaving M (M is an even number of 4 or more) cords of equal length,
Aligning the tips of the M core wires and arranging them in parallel;
One of the two core wires located at both ends is one of the two core wires located in the center at the downstream position of the braided direction from the tip, and the one of the two core wires as viewed from the center. A core wire positioned between one of the core wires positioned at both ends and one of the core wires positioned at the center and a core wire positioned at the center toward the core wire positioned on the same side as the core wire One of the cores located at both ends is alternately crossed from the upper side or the lower side and then from the lower side or the upper side, respectively, in order from the outside to the other. Is located at the center, and the other of the two core wires located at both ends is the other core wire of the two core wires located at the center at the position downstream of the leading end in the weaving direction. To the core located on the same side as the other core as viewed from the center Thus, a core wire located between the other of the wires positioned at the both ends and the other of the core wires positioned at the center and the other of the core wires positioned at the center, in order from the outside, to the both ends. A first cross step of alternately crossing the other one of the cores located from the upper side or the lower side and then from the lower side or the upper side, so that the other of the cores located at both ends is located in the center; ,
The core wire located in one of the centers is crossed from the upper or lower side with the core wire located in the other center in the position of the wake in the weaving direction from the position crossed last in the first cross step, A second cross step in which the left and right core wires located in the center after the first cross step are switched; and
It is a first repetition step that repeats the first cross step and the second cross step until returning to the order in which the core wires were initially arranged, and in the first cross step, the weaving direction from the tip portion A first repetitive step, wherein the cross is started not at the position of the wake but at the position of the wake in the weaving direction from the position crossed last in the second cross step. A method of weaving a multi-core core group.   The method of weaving a multi-core type core wire group according to claim 1, further comprising a second repetition step for repeating the first repetition step. A method of weaving multi-core core groups to create a multi-core core group by weaving N (N is an odd number greater than or equal to 3) core cores of equal length,
Aligning the tips of the N core wires and arranging them in parallel;
The core wire located at one end is in the wake flow direction from the tip portion, in order from the outer side with respect to the core wire located at the center side, from the upper side or the lower side, and then from the lower side or the upper side. A first cross step that is alternately crossed so that the core wire originally located at one end is located in the center;
The core wire located at the other end is located downstream from the position at which it was last crossed in the first cross step, in the knitting direction, from the upper side or the lower side in order from the outer side with respect to the core wire located at the center side. A second cross step that alternately crosses from the lower side or the upper side so that the core wire originally located at the other end is located at the center;
It is a first repetition step that repeats the first cross step and the second cross step until returning to the order in which the core wires were initially arranged, and in the first cross step, the weaving direction from the tip portion A first repetitive step, wherein the cross is started not at the position of the wake but at the position of the wake in the weaving direction from the position crossed last in the second cross step. A method of weaving a multi-core core group.   The multi-core type wire group knitting method according to claim 3, further comprising a second repetition step for repeating the first repetition step. A method of knitting a multi-core type core group to create a multi-core type core group by knitting two cores having the same length,
Aligning the tips of the two core wires and arranging them in parallel;
Crossing one of the two cores with the other of the two cores for every predetermined length from the tip, and a method of weaving a multi-core group of cores, .   6. The method of braiding a multi-core type core wire group according to claim 1, wherein the core wire is an optical fiber core wire.   The multi-fiber core according to claim 6, wherein when the optical fiber cores are knitted, a radius of curvature of a bent portion in each of the optical fiber cores is in a range in which no bending loss occurs. How to weave a group of lines.   The multi-core type core group according to claim 6 or 7, wherein the optical fiber core is any one of a double core optical fiber, a trench type optical fiber, and a photonic crystal fiber. Weaving method.   The multi-core type core wire according to any one of claims 1 to 5, wherein the core wire is any one of an electric cable, a cable for telecommunication, and a thin coaxial cable. How to weave groups.

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