JP2011081089A - Plastic optical fiber connection cable - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a multi-core connection cable having deformable connection parts 14 obtained by connecting optical fiber codes 13 which are composed of three or more optical fibers 11 and individually coated with sheaths 12, together with resin, wherein even after the individual cables are bundled by bending the connection parts 14, the curling habit hardly occurs. <P>SOLUTION: The individual connection parts 14 are disposed along at least one of tangents not crossing each other, among tangents connecting between the outer circumferences of the optical fiber codes 13 disposed parallel to each other, and also, the connection parts 14 are discontinuous in at least one of the optical fiber codes. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a multi-core plastic optical fiber connecting cable mainly used for wiring in equipment such as a television.

  Conventionally, metal cables have been used for signal transmission equipment wiring used in televisions, etc., but in order to make these electronic devices thinner and smaller, cables with thinner diameters and handling are more There is a need for easy cables. In addition, for internal cables, cables that use optical fibers have been used for high speed from metal cables that transmit electrical signals. Cables using plastic optical fibers are attracting attention because of their ease.

  Furthermore, with an increase in the amount of signals exchanged in the device, a single-wire optical fiber is not sufficient, and a multi-core plastic optical fiber is formed into a single cable. However, with a cable that simply bundles multiple cores, it is difficult to handle the wiring in the device, which requires a reduction in thickness and has a small space. On the other hand, a simple flat cable is effective for passing a gap, but bending becomes inconvenient. For this reason, there is a demand for a wiring cable that can be passed in a flat cross-sectional shape at a narrow width and can be bent and bent into a circular cross-sectional shape at a bent portion.

  On the other hand, as described in Patent Document 1, a plurality of core wires arranged in parallel with each other are individually covered with a resin as described in Patent Document 1, and the space between the coatings is made of a thin resin. There has been proposed a multi-core type connecting cable that is connected at a connecting portion along a coated core wire. The connecting portions are formed by connecting the individual core wires in parallel so as to have a flat shape, and in a state where no force is applied, the cross section is connected in a straight line as shown in FIG. On the other hand, at the place where the bending is necessary, the thin connecting portions are bent to bundle the individual core wires in a round shape and housed in the tubular tube 6 so that the cross-sectional contour can be circular as shown in FIG.

Japanese Utility Model Publication No. 63-135713

  However, when the connecting cable 1 as shown in FIG. 18 is bundled in a circular cross section as shown in FIG. 19, the connecting portion 5 is strongly bent as a whole. Further, even if the adjacent optical fiber cords 4 are integrated together, the connecting portions 5 are provided along the line passing through the core, so that the connecting portions 5 cannot be concentrated on the central portion, Regardless of the direction in which all of the connecting parts 5 are bent, there is a large difference between the force at which the inner connecting part is contracted and the force at which the outer connecting part is stretched. Was supposed to be greatly received.

  For this reason, even if it tried to mutually convert into a cross-sectional flat shape and a cross-sectional circular shape and to arrange | position a cable, bending was inconvenient, the load concerning a connection part became large easily, and the freedom degree of wiring was not enough. Further, the connecting cable is likely to be bent, and it may be difficult to return the connecting cable once bundled and accommodated in a cylindrical tube to have a circular cross section. Furthermore, when accommodating a plurality of connecting cables in a single tube, it is difficult to fold, and as a result, the required inner diameter of the tube tends to increase.

  Therefore, the present invention reduces the burden on the connecting part as a whole in a multi-core connecting cable having a flexible connecting part for deforming the whole into a circular cross section or an elliptical cross section and a flat cross section. An object of the present invention is to improve the working efficiency of wiring work using a connecting cable by improving the degree of freedom in handling when bending.

  The present invention relates to a tangent that does not intersect among tangents that connect the outer circumferences of optical fiber cords arranged in parallel with individual connection portions that connect optical fiber cords including a plastic sheath covering an optical fiber. The above-mentioned problems have been solved by providing along one of the optical fiber cords, and disposing the connecting portions discontinuous in at least one optical fiber cord. Here, the outer periphery is the outer periphery of a circle when the cross-sectional shape of the sheath is assumed to be a circle. There are four tangents connecting two circles, two of which intersect, but the connecting portion according to the present invention is provided along any one of the two tangents that do not intersect. . In this application, the optical fiber means an optical fiber having both a core and a clad made of plastic. The individual optical fiber strands are in a positional relationship in which they are arranged in parallel with a space between each other, and they are connected by a sheath and a connecting portion.

  When attention is paid to one optical fiber cord connected to the discontinuous connecting portion, the contacts that are the basis of each connecting portion are in a state of 180 ° positional relationship. In other words, this is a state where the connecting portions are alternately provided at the upper and lower positions when the connecting portions are extended in a flat cross section and spread on a plane. However, when the optical fiber cord is composed of five or more cores, the connecting portion may not be discontinuous in all the optical fiber cords. This is because it is difficult to dispose the optical fiber cord when the connecting portions are bent when all the connecting portions are discontinuous with five or more cores.

  By providing the connecting portion at a position along the tangent line, when the optical fiber cord is bundled, it is possible to make it easier to collect many of the connecting portions in the center than in the conventional model, and by providing a discontinuous portion It is possible to cope with both inner and outer bends, and a sufficient degree of bending can be secured.

  Thereby, when a plurality of connecting cables are bundled, the optical fiber cord of another connecting cable can be easily arranged in the gap between the connecting cables, and the inner diameter of the tube for bundling a plurality of connecting cables can be reduced.

  The optical fiber strands to be connected are three or more cores, and the effect of the invention is particularly exerted with four or more cores. With two cores, there is almost no effect by bundling optical fiber cords and storing them in a tube. The number of cores is not particularly limited, but if it exceeds 10 cores, even if the connecting portions are bent and the cords are bundled, interference between the connecting portions becomes severe, and the effect of the present invention cannot be exhibited so much. Preferably it is 4-6 cores.

  In the case of four or more cores, it is preferable that the structure has two optical fiber cords with discontinuous connecting portions, and the cross section is line symmetric with respect to the width direction of the connecting cable. That is, it is a shape in which the connecting part is divided into three parts, both end parts and a central part. By folding the connecting parts at both ends so that they are adjacent to each other without moving the central connecting part, the connecting parts can be easily combined and easily bent in the same plane direction as the flat part, which is difficult to bend when flat. Will be able to.

  The outer diameter of the optical fiber using this invention is preferably 0.25 mm or more and 3 mm or less. If it is thinner than 0.25 mm, the advantages of plastic optical fibers such as ease of handling and connection are impaired. On the other hand, when it exceeds 3 mm, it becomes difficult to bend, and the merit of the connecting cable according to the present invention can hardly be utilized. Moreover, it is preferable that the thickness of the sheath covering the optical fiber is 0.1 mm or more and 0.5 mm or less. If the thickness is less than 0.1 mm, the coating effect is not sufficient. On the other hand, if it exceeds 0.5 mm, the optical fiber cord becomes unnecessarily thick and obstructs handling. Accordingly, the outer diameter d of the optical fiber cord composed of the optical fiber and the sheath is preferably in the range of 0.45 mm to 4 mm.

  The thickness T of the connecting portion is preferably 0.5 mm or less in order to facilitate bending. On the other hand, if the thickness T is not greater than 0.1 mm, the possibility of tearing when bending is not negligible. Preferably it is 0.2 mm or more. Further, in order to facilitate the bonding of the connecting portions at the positions of being symmetrical to the tube or when being accommodated in the tube, in relation to the optical fiber cord, the thickness T is the sheath outer diameter d of the connected optical fiber cords. It is preferable that it is 1/2 or less of this, and more preferably 1/6 or less of the outer diameter d.

  Furthermore, the center-to-center distance L of the optical fiber strands separated by the connecting portion is preferably 1 to 3 times the outer diameter d of the optical fiber cord. Preferably it is 1.5 times or more.

  When the connecting cable according to the present invention is used, it is easy to handle a portion having a flat cross section and a circular portion in a cross section, and the signal cable can be easily arranged in a narrow and complicated electronic device. That is, the bending in the direction of rising from the flat cross-sectional portion can be bent with the flat cross-sectional shape. On the other hand, when bending in the same plane direction as the portion having the flat cross section, the connecting portion is bent so that the circular cross section is formed, the cords are bundled, and the one accommodated in the tube is bent. Since the difference in the radius of curvature between the outer connecting portion and the inner connecting portion is small, the load applied to the connecting cable is reduced, and it is possible to make it less likely that breakage or bending wrinkles will remain. . In the case of specific wiring, wiring is performed so that the straight part and the narrow part are as flat as possible, and the bent part in the direction in which it is difficult to bend with the flat part is circular or cross-sectional Wiring is performed by the portion accommodated in the elliptical tube, thereby enabling effective handling even in a complicated and narrow electronic device. In addition, if the cord can be bundled, such as a spiral-shaped binding tool or a binding tool having a stopper, it can be used in place of the tube.

  In the case of using a tube, the sheath and the connecting portion are formed and the tube may be formed and stored in the tube in advance. You may make it accommodate in a cylindrical thing. If the tube is stored in advance, tear the tube as necessary, open the connecting part where almost no bending wrinkles remain, open it in a flat cross-section, bend it in the direction rising from the flat part, or thin the flat part It is possible to pass through the gap using.

  In addition, in the case of a connecting cable having a line-symmetrical section or a connecting cable having a line-symmetrical part, the central connecting part is left as it is instead of being accommodated in the tube when the flat part is bent in the plane direction. It is also possible to easily perform bending by setting the positions and connecting the connecting portions at both ends together by bonding the surfaces corresponding to the tangent lines of the optical fiber cord. Place the narrow section or the direction rising from the flat surface as it is in the flat shape of the cross section, and if the flat section of the cross section needs to be bent in the flat direction or the narrow portion in the width direction of the connecting cable, bend the connecting portion together Or pass through a gap.

Schematic of a connecting cable consisting of four cores according to the first embodiment AA cross-sectional view of FIG. 1 (cross-sectional view in a flat shape without applying external force) BB cross-sectional view of FIG. 1 (cross-sectional view in a tubular shape by a tube) Conceptual diagram showing the tangential direction of the outer periphery of the optical fiber cord where the connecting part is discontinuous and extends vertically Conceptual diagram of tangent line connecting two circles Sectional view when the connecting parts at both ends are bonded in the first embodiment Schematic when bending left and right in the adhesive state of FIG. Schematic when bending in the direction of rising from a flat surface in a flat state Sectional view when bent in the opposite direction to FIG. 3 in the first embodiment Sectional drawing of the form which accommodated the four connection cables concerning 1st embodiment in the cross-sectional elliptical tube Sectional drawing of the connection cable which consists of six cores concerning 2nd embodiment Sectional drawing of the form which bent and connected the connection cable concerning 2nd embodiment in the tube Sectional drawing of the connection cable which consists of six cores concerning 3rd embodiment Sectional drawing of the connection cable which consists of 5 cores concerning 4th embodiment Sectional drawing when accommodating the connecting cable according to the fourth embodiment in a tube having a circular cross section Sectional drawing of the continuous cable which consists of 5 cores concerning 5th embodiment Sectional drawing of the continuous cable which consists of 5 cores concerning 6th embodiment Cross-sectional view of a conventional connecting cable Sectional drawing of the form which accommodated the conventional connection cable in the tube

Hereinafter, specific embodiments for carrying out the present invention will be described.
The optical fiber connecting cable according to the present invention is a flexible connecting connection made of a thin resin between individual optical fiber cords 13 in which individual optical fiber strands 11 are covered with resin to form a sheath 12. This is a multi-core type cable connected at the portion 14.

  A first embodiment of the present invention is shown in FIGS. FIG. 1 is a schematic view of a portion of the connecting cable of the first embodiment that switches between a cylindrical section in cross section and a flat cross section. FIG. 2 is a cross-sectional view of a portion (AA in FIG. 1) having a flat cross-sectional shape of the connecting cable according to this embodiment. FIG. 3 is a cross-sectional view of a portion (BB in FIG. 1) having a circular cross section of the connecting cable according to this embodiment.

  In the first embodiment, four optical fiber cords 13 that individually cover four optical fiber strands 11 to form a sheath 12 are arranged in parallel at intervals, and a connecting portion 14 is provided therebetween. Are connected. In an open state where no force is applied from the outside, the optical fiber cord 13 composed of the optical fiber 11 and the sheath 12 is arranged in a line as shown in FIG. The connecting portions 14 that connect the individual optical fiber cords 13 are all discontinuous at the individual optical fiber cords 13, and are formed at point-symmetric positions with the center of the cable as the center of symmetry. That is, the connecting portion 14a that connects the two inner optical fiber cords 13a and 13a and the connecting portion 14b that connects the inner optical fiber cord 13a and the outer optical fiber cord 13b are alternately provided in the vertical direction. A connecting cable 10 is formed.

FIG. 4 is a conceptual diagram showing the relationship between the connecting portion 14 and the optical fiber cord 13. A circle indicates the outer periphery of the cross section of the sheath 12, and a small circle in the middle indicates a cross section of the optical fiber 11. One of the connecting portion 14, extends in a tangential direction extending from the point T ₀ on the circle. Another connecting portion 14 extending from the optical fiber cord 13 of this embodiment has a positional relationship in which the central angle between the contact T ₀ and the contact T ₁ is 180 degrees, and similarly extends from the contact T _1. Yes.

  Note that four tangent lines connecting two separated circles can be drawn as shown in FIG. The connecting portion provided in the present invention is not a crossing tangent (shown by a broken line in the figure) among the tangents, but is along one of the non-crossing tangents.

  In the connecting cable according to this embodiment, the connecting portions 14 are alternately provided, so that when the optical fiber cords 13 are bundled, they can be easily brought into close contact with each other. FIG. 6 shows a cross-sectional shape at the time of the close contact. The pair of optical fiber cords 13 are in close contact with each other so that the central connecting portion 14a is on the outside of the bend and the connecting portions 14b on both ends are on the inside of the bend. At this time, the adjacent connecting portions 14b may be bonded with an adhesive or a double-sided tape as necessary. In this shape, as shown in FIG. 7, when the bundled connecting cable 10 is bent in the left-right direction of FIG. 6, that is, in the plane direction of the original flat portion, the connecting portion 14 b that is the inner side and the connecting portion that is the outer side. The difference in the radius of curvature of the bending with respect to 14b can be made substantially zero, the load caused by the force to expand the outer side and shrink the inner side is reduced, and bending in the left-right direction can be easily performed. At this time, since the central connecting portion 14a is also located at the center in the left-right direction of the bundle, distortion applied to the connecting portion 14a can be minimized.

  Conversely, when the connecting cable is to be bent in the vertical direction in FIG. 6, the distortion caused by the bending is minimized by returning the bundled cable as shown in FIG. 6 to the flat shape as shown in FIG. Can do. The bending method at this time is shown in FIG. When rising from the same plane as the flat shape portion, the loads applied to the connecting portions 14a, 14b and the optical fiber cords 13a, 13b are almost the same, and can be easily bent as shown in FIG.

  On the other hand, when the optical fiber cords 13 of the connecting cable 10 are bundled, the central connecting portion as shown in FIG. 9 is opposite to the so-called “outward bending” in which the central connecting portion 14a is arranged outside as shown in FIG. It can also be summarized by so-called “inner bending” in which the portion 14a is arranged on the inner side. However, when this bundling is performed, when the connecting cable 10 is bent in the left-right direction, with respect to each connecting portion 14b arranged at both the left and right ends, the connecting portion located inside and the connecting portion located outside, Since such a difference in force is large, in most cases, it is preferable to accommodate by “outside bending”.

  When this “outside bending” is performed, the cross-section of the bundled connecting cable has a substantially U-shape with a deep depth. By utilizing this depth, the U-shaped portions of the two connecting cables 10 are engaged with each other, so that the occupied outer diameter can be made smaller than that of the conventional connecting cable. FIG. 10 shows a cross-sectional view when a plurality of connecting cables 10 are bundled together with a tube 19 in this manner.

  Specifically, in connection with the accommodation in the tube 16, the connecting cable 10 according to the first embodiment requires a single connecting cable 16 as compared with the conventional connecting cable 1 shown in FIGS. 18 and 19. Has an inner diameter of 123%, ie an increase of 23%. However, when compared with a combination of two connecting cables, the inner diameter of the tube 16 (19) required by the connecting cable 10 according to the first embodiment is 88% that of the conventional connecting cable 1 and four. In the combination, it is reduced to 85% in the case of the conventional connecting cable 1. That is, as the number increases, the connection cable 10 according to the first embodiment has a discontinuous portion along the tangent line than the conventional connection cable provided at the center. Since the side without the connecting portion opens greatly, it can be engaged deeply, and the required inner diameter of the tube can be reduced.

  When bundling a plurality of connecting cables 10 as shown in FIG. 10, if the tube 19 has an elliptical cross section, the occupied space may be made smaller than when the tube 19 has a circular cross section. Even when one connecting cable 10 is bent and accommodated, for example, when the connecting portions 14b at both ends are bonded to each other as shown in FIG. .

  The entire connecting cable 10 may be stored in the tube 16 in advance, or a part of the connecting cable 10 may be stored in the tube 16 as necessary. Mounting in the tube 16 in advance and tearing the tube 16 as necessary to expose the connecting cable 10 can be easily installed in the apparatus. Moreover, since the connection part of the connection cable concerning this invention satisfy | fills said conditions, when it open | releases from the tube 16, it will return to a flat shape, leaving almost no bending wrinkles. On the other hand, when the portion to be routed with the flat shape is long, the connecting cable 10 is wired with the flat shape, and only the necessary bent portion is accommodated in the tube to form a bent shape. In particular, when the portion to be bundled is short, the optical fiber cord 13 may be bundled with a spiral-shaped binding tool or a binding tool having a retaining stopper instead of the partially accommodated tube.

  The inner diameter of the tube 16 needs to be able to accommodate at least the connecting cable 10 deformed at the connecting portion. On the other hand, if the inner diameter is too large, the optical fiber strands 11 cannot be bundled, and the connecting cable 10 becomes close to an open state inside the tube 16. In the case of four cores as in the first embodiment, the inner diameter is preferably not more than twice the center-to-center distance L.

  Moreover, the deformation | transformation part 17 between the part (equivalent to the back | inner side of FIG. 1) covered with the tube 16 and the part made into the open state of a cross-sectional flat shape (equivalent to the near side of FIG. 1) is the It is better to cover it with resin tape.

  As the method for forming the connecting portion 14, the sheath 12 and the connecting portion 14 may be extruded with the same resin so as to be integrated, or the optical fiber is once covered with a resin dedicated for coating. After the sheath 12 is formed, the connecting portion 14 may be formed separately. If formed individually, there is a drawback that the number of manufacturing steps increases. However, since the sheath 12 and the connecting portion 14 are made of resin suitable for each, the connecting cable 10 is superior in terms of physical properties.

  The thickness T of the connecting portion 14 needs to be equal to or less than half of the outer diameter d of the sheath 12. This is because if it is thicker than that, it is difficult to bend the connecting portion 14 to an appropriate angle in order to bundle the optical fiber strands 11. On the other hand, the thickness T needs to be at least 0.1 mm or more. This is because if the thickness is less than 0.1 mm, the film is too thin, there is a problem in strength, and tearing may occur.

  Further, the length of the connecting portion 14 (center-to-center distance L) needs to be 1 to 3 times the outer diameter d of the sheath 12, and is preferably 1.5 times or more. If it is less than 1 time, there is too little play, and there is a high possibility that it will be difficult to sufficiently bend the connecting portion 14 in order to bundle the optical fiber strands 11. On the other hand, if it exceeds three times, the gap between the optical fiber strands 11 is unnecessarily opened, and it becomes an obstacle when the connecting portion 14 is bent, and it becomes difficult to accommodate the tube 16 or the diameter of the tube 16 is unnecessarily increased. It must be enlarged, and on the contrary, handling inside the device becomes difficult.

  The center-to-center distances L are preferably equal pitches, but may be different as long as the values are within the above ranges.

  Moreover, although it is preferable that each optical fiber strand 11 is the same, it does not necessarily need to be the same. When the diameters of the optical fiber strands 11 are different, the size based on the outer diameter d may be based on the outer diameter d of the optical fiber cord 13 having the maximum diameter.

  In the present invention, the resin for forming the connecting portion 14 having the above dimensions preferably has a durometer D hardness of 55 or less. Rather than simply using the resin used for coating as it is, by using a resin that satisfies this condition, the formed connecting portion is less likely to be bent, and even if the individual optical fiber cords 13 are bundled, they are opened. Thus, the flat shape can be quickly restored.

  In addition to the above-mentioned durometer D hardness condition, the resin for forming the connecting portion 14 preferably satisfies the condition that the melt flow rate at 190 ° C. is 10 g / 10 min or more and 100 g / 10 min or less. . When the value of the melt flow rate satisfies this condition, the moldability under the above size conditions is improved, and an increase in the optical loss of the optical fiber can be avoided.

  As the specific difficulty of bending the resin, when the sheet is 1 mm thick, it is held in a cylinder with an inner diameter of 25 mmφ for 60 minutes, and the curvature of the sheet that is returning to a flat shape after 60 minutes has elapsed after release. It is preferable if the radius is 80 mm or more. The larger the radius of curvature is, the more preferable, and it is most preferable to return to infinity, that is, a complete plane.

  Examples of the resin that satisfies such a value include polyvinyl chloride resin, low density polyethylene (LDPE), linear low density polyethylene (LLDPE), and mixed resins of these with other resins. Examples of the resin mixed with LDPE or LLDPE include ethylene-propylene-diene rubber (EPDM) and chlorinated polyethylene (CPE). In particular, by mixing an appropriate resin with LDPE or LLDPE, the physical properties required for the above resin can be easily satisfied.

  Specific examples of the mixed resin include a mixed resin of LLDPE and EPDM in a weight ratio of 90:10 to 40:60, and a mixed resin of LLDPE and CPE in a weight ratio of 90:10 to 40:60. Among these mixed resins of LDPE and LLDPE, especially these two mixed resins have good coating removal properties, so that the connecting work and the sheath are peeled off to expose the optical fiber strands, and the attachment workability when connecting to the multi-core batch connector is good. There is an effect.

  Next, the connecting cable 20 according to the second embodiment will be described with reference to a cross-sectional view shown in FIG. In this embodiment, six optical fiber cords 21 (21a to 21c × 2) are arranged in parallel and connected by connecting portions 22 (22a, 22b × 2, 22c × 2). The configurations of the individual optical fiber cords 21 and the connecting portions 22 may be the same as those of the optical fiber cords 13 and the connecting portions 14 in the first embodiment.

  In the second embodiment, the connecting portions 22a that connect the two central optical fiber cords 21a and the connecting portions 22b that extend from the optical fiber cords 21a to the adjacent optical fiber cords 21b are alternately discontinuous. It is provided. Further, the connecting portions 22b and 22c extending from the optical fiber cord 21b are continuous. That is, from the first embodiment shown in FIG. 2, the connecting portions at both ends are extended and optical fiber cords are respectively provided at the ends. There are two places where the connecting portions are discontinuous, and the shape is axisymmetric in the width direction. When the connecting portion 22 of the connecting cable 20 is bent, if the center connecting portion 22a is bent outward, the load applied to the entire connecting cable 20 becomes relatively small. FIG. 12 shows a cross-sectional shape when the connecting cable 20 is accommodated in the tube 23 having an elliptical cross section. Similar to the first embodiment, in this state, even when bent in the left-right direction in the figure, the distortion between the inner connecting portion and the outer connecting portion is small.

  It is also easy to bend in the left-right direction by adhering the connecting portions 22b and 22c together instead of being housed in the tube.

  Next, the connecting cable 20 'according to the third embodiment will be described with reference to a cross-sectional view shown in FIG. This is similar to the second embodiment, in which six optical fiber cords are arranged in parallel, but extend from four optical fiber cords 21a, 21a, 21b, 21b other than the optical fiber cords 21c at both ends. All the connecting portions extend alternately and are discontinuous. Since the connecting cable 20 'can be folded independently, the occupied space can be reduced because the connecting cable 20' can be folded by itself, but since the number of connecting parts that turn to the outside increases, distortion at the time of bending is more than that of the second embodiment. Slightly bigger.

  Furthermore, the connecting cable 25 according to the fourth embodiment will be described with reference to a cross-sectional view shown in FIG. In this example, five optical fiber cords 26 are arranged in parallel. The connecting portions 27a and 27a connecting the central optical fiber cord 26a and the adjacent optical fiber cords 26b and 26b are continuous. The connecting portions of the optical fiber cords 26b and 26b are discontinuous, and the connecting portions 27b and 27b connected to the optical fiber cords 26c and 26c at both ends are alternately arranged with the two connecting portions 27a and 27a at the center. Is formed.

  When the connecting cable 25 according to this embodiment is to be bent in the same plane direction as the flat portion, it is difficult to bond the connecting portions 27b and 27b at both ends because the central optical fiber cord 26a becomes an obstacle. It is. For this reason, as shown in FIG. When accommodated in the tube 28, it is preferable to bend the connecting portions 27b and 27b at both ends so as to be inside. This is because when these are gathered in the center, the distortion applied to the connecting portion is reduced by the amount of bending in the left-right direction in FIG.

  Furthermore, the connecting cable 25 'according to the fifth embodiment will be described with reference to a cross-sectional view shown in FIG. In this example, five optical fiber cords 26 are arranged in parallel, and a continuous connecting portion is provided from one of the optical fiber cords at both ends of the connecting cable 10 according to the first embodiment. Shape. It is asymmetrical in the width direction, and if it tries to be accommodated in the tube, the balance between the left and right will be lost, and the distortion at the time of bending will be larger, so it will be disadvantageous for bending than the fourth embodiment. Since the optical fiber cord 26e and the optical fiber cord 26f in which the connecting portions are discontinuous are adjacent to each other, when accommodated in the tube, there is an advantage that it can be made more compact than the fourth embodiment. . Further, instead of being housed in the tube, the connecting portion 27c and the connecting portion 27e can be bonded together as in FIG. 6 of the first embodiment.

  Furthermore, the connecting cable 25 ″ according to the sixth embodiment will be described with reference to a cross-sectional view shown in FIG. This is also one in which five optical fiber cords 26 are arranged in parallel, but are formed so that all the connecting portions are alternated. That is, with the optical fiber cord 26i at the center as the center, the adjacent optical fiber cords 26j, the optical fiber cords 26k at both ends, and the connecting portions that connect them are in a point-symmetrical positional relationship. Since all the connecting portions are provided alternately, when the connecting portions are bent and accommodated in the tube, the connecting portion can be made more compact than the fifth embodiment. Further, similarly to FIG. 6 of the first embodiment, the continuous portion 27h and the continuous portion 27g can be bonded together. On the other hand, since there is an articulated portion that increases the distortion regardless of how it is bent, bending is slightly disadvantageous than the fourth and fifth embodiments.

  That is, the discontinuous portions are preferably two places in the entire connecting cable, and the two places may be positions that are line symmetrical in the width direction. Further, when the number of the optical fiber cords is six or more, it is preferable that the optical fiber cords in which the connecting portions are discontinuous are adjacent or have one optical fiber cord sandwiched therebetween. However, this condition is the case where the number of optical fiber cords is 8 or less, and when the number exceeds that, even if there are only two discontinuous portions, it may be bent only at the discontinuous portions. Since the whole becomes too long, it is desirable to increase the number of discontinuous portions.

  Hereinafter, examples in which the present invention is specifically implemented will be described. 2 and 3, the connection cable (Example) according to the first embodiment and the conventional connection cable (Comparative Example) shown in FIGS. In both cases, the coating and connecting parts were made of polyvinyl chloride resin.

  For each example, a connection cable having a connection portion with a total distance L between the centers of the connection portions of 50 mm and a thickness of 1 mm and an outer diameter d of the sheath of 5.5 mm was manufactured. The entire connection cable was held for 60 minutes in a state bent to 25 mmφ, and the radius of curvature (mm) of the central connection portion after 60 minutes was measured after release. However, about the Example, both said outer bending and inner bending were measured.

  The inner bend of the example was 124 mm and the outer bend was 145 mm, and it was found that the outer bend is less likely to bend. On the other hand, it was 80 mm in the comparative example, indicating that bending folds were easier than in the examples, and that handling was inconvenient.

DESCRIPTION OF SYMBOLS 1 Connection cable 2 Optical fiber strand 3 Sheath 4 Optical fiber cord 5 Connection part 6 Tube 10 Connection cable 11 Optical fiber strand 12 Sheath 13 Optical fiber cord 13a (inner side) Optical fiber cord 13b (outer side) Optical fiber cord 14 Connecting portion 14a (Center) Connecting portion 14b (Both ends) Connecting portion 16 Tube 17 Deformed portion 19 (Oval cross section) Tube 20, 20 '(Second and third) connecting cable 21 (21a to 21c) Optical fiber Cord 22 (22a-22c) Connecting portion 23 Tubes 25, 25 ', 25''(fourth, fifth, sixth) connecting cable 26 (26a-26k) Optical fiber cord 27 (27a-27h) Connecting portion

Claims (11)

Three or more plastic optical fiber strands are arranged in parallel at intervals, and each of the optical fiber strands is covered with a resin sheath, and is composed of the optical fiber strand and the sheath. A connecting cable provided with a flexible connecting portion made of resin that connects optical fiber cords along the optical fiber cord,
Each of the connecting portions is provided along one of the tangents that do not intersect among the tangents connecting the outer peripheries of the adjacent optical fiber cords,
A connecting cable characterized in that, in at least one of the optical fiber cords other than both ends, two connecting portions connected to the optical fiber cord are alternately provided so as to be discontinuous.   The optical fiber cord is composed of four or more optical fiber cords, and two of the optical fiber cords in which the two connecting portions to be connected are discontinuous are two of them, and the cross section is line symmetric in the width direction of the connecting cable. Connecting cable.   The connecting cable according to claim 1 or 2, wherein a thickness of the connecting portion is equal to or less than an outer diameter of the optical fiber cord, and a resin forming the connecting portion is a resin having a durometer D hardness of 55 or less.   The connecting cable according to any one of claims 1 to 3, wherein a melt flow rate at 190 ° C of the resin forming the connecting portion is 10 g / 10 min or more and 100 g / 10 min or less.   The connecting cable according to any one of claims 1 to 4, wherein the resin forming the connecting portion is a polyvinyl chloride resin, a linear low-density polyethylene, or a low-density polyethylene.   The resin forming the connecting part is a linear low-density polyethylene or a mixed resin obtained by mixing low-density polyethylene and ethylene-propylene-diene rubber in a weight ratio of 90:10 to 40:60. The connecting cable according to any one of the above.   The resin forming the connecting portion is a linear low-density polyethylene or a mixed resin obtained by mixing low-density polyethylene and chlorinated polyethylene in a weight ratio of 90:10 to 40:60. The connecting cable according to claim 1.   The cable which bonded together the surfaces which correspond to the said tangent of the two connection parts located at both ends about at least one part of the length direction of the connection cable of any one of Claim 1 thru | or 7.   The connecting cable according to claim 8, wherein at least a part of the flat part not bonded together is arranged, and a surface of the connecting part is provided at a bent part in the same plane direction as the flat part. An in-device wiring method that places the bonded parts together.   The cable which accommodated at least one part of the length direction of the connecting cable of any one of Claim 1 thru | or 7 in the tube of cross-sectional circular shape or cross-sectional ellipse shape.   Using the cable according to claim 10, at least a flat portion not covered by the tube is disposed, and a bent portion in the same plane direction as the flat portion has a circular cross-section or a cross-sectional oval shape by the tube. Wiring method in the equipment to place the part that was done.

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