JP2006154448A - Optical fiber cord - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical fiber cord capable of preventing force from applying onto optical fibers. <P>SOLUTION: The optical fiber cord 2 has two lines of optical fibers 8 and a high-tension wire 19 which is arranged between these optical fibers 8. The optical fiber 8 is covered with a first covering part 20 by being closely adhered to it. A second covering part 21 consists of optical fiber parts 21a each of which covers the optical fiber 8 and the first covering part 20 and a connecting part 21b which covers the high-tension wire 19. The thickness D4 of the connecting part 21b is made thicker than the thickness D3 of the optical fiber part 21a. When the optical fiber cord 2 is passed through the inside of piping, force is applied to the connecting part 21b and large force is not applied to the optical fiber parts 21a. Thus, the optical fibers 8 are never deformed, and the lowering of communication characteristics can be prevented. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an optical fiber cord, and more particularly to a multi-core optical fiber cord.

  An optical fiber is known as a transmission medium for transmitting a large amount of information. Optical fibers are widely used from short-distance optical communications to long-distance optical communications. When the optical fiber is used for short-distance optical communication, for example, optical communication indoors or in a premises, the optical fiber is coated with an optical fiber to increase the mechanical strength. The optical fiber cord is routed through a pipe such as a CD pipe or duct installed indoors or on the premises.

  A plastic optical fiber (hereinafter referred to as POF) is often used as an optical fiber of an optical fiber cord laid indoors or on the premises. In the POF, the core and the clad are both made of plastic. Although POF has a slightly larger transmission loss than silica-based optical fiber, it has advantages such as ease of terminal processing, ease of connection with peripheral devices, and low cost.

  Conventionally, a zip type two-core optical fiber cord 100 having a cross section as shown in FIG. 11 has been often used as an optical fiber cord laid indoors or in a premises. The optical fiber cord 100 has two optical fiber strands 103 each composed of a core 101 and a clad 102. The optical fiber 103 is covered with a first covering portion 104, and a tensile strength wire 105 is disposed around the first covering portion 104. The tensile strength line 105 is used to give the optical fiber cord 100 a sufficient tensile strength. A loose second covering portion 106 is formed on the outermost side.

  However, when the optical fiber cord 100 is laid indoors or on the premises, force may be applied to the optical fiber cord 100 during and after wiring into the pipe. When a force is applied to the optical fiber cord 100, the covering portions 104 and 106 and the tensile strength wire are deformed, which causes a problem that the communication characteristics of the optical fiber 103 are adversely affected. Further, at the end portion of the optical fiber cord 100, there is a problem that the terminal process becomes complicated because the tensile strength wire 105 becomes an obstacle during the terminal process in which a part of the optical fiber 103 is exposed.

  An object of the present invention is to provide an optical fiber cord that can prevent a force from being applied to an optical fiber during and after wiring. It is another object of the present invention to provide an optical fiber cord that can easily process a tensile strength wire during terminal processing.

  The present invention relates to an optical fiber cord comprising an optical fiber, a first covering portion that covers the optical fiber, and a second covering portion that covers a plurality of the first covering portions. And the first covering portions are spaced apart from each other and are connected by the second covering portion, and the second covering portions are perpendicular to a plane including the central axis of two adjacent optical fiber strands. And a portion having a thickness larger than the thickness on a line orthogonal to the central axis on the plane. The portion having the large thickness is disposed in a region between the optical fiber strands, a region further outside the outermost optical fiber strand, or the like.

  It is preferable that a tensile strength wire is provided in at least one region of the end portion of the second covering portion or the portion between the optical fiber strands, and the tensile strength wire is disposed so as to be covered by the second covering portion. . In particular, the tensile strength line is preferably disposed so as to be covered with the portion having the large thickness. As the material of the tensile strength wire, a resin such as FRP is preferable. The material of the tensile strength line is preferably a non-metal. Further, the tensile strength material is preferably non-glass.

  It is preferable that the first covering portion is in close contact with the optical fiber. It is preferable that a groove for tearing the second covering portion is formed on the outer peripheral surface of the second covering portion in parallel with the axis of the optical fiber.

  It is preferable that the number of the optical fiber is two. Further, the number of the optical fiber strands may be three or more. When there are three or more optical fiber strands, it is preferable that these optical fiber strands are arranged on substantially the same plane.

  The optical fiber preferably has a numerical aperture of 0.15 or more. Moreover, it is preferable that the said optical fiber strand is made into the range whose core diameter is 90-650 micrometers.

  The optical fiber strand is preferably a multimode optical fiber strand. The optical fiber is preferably a graded index optical fiber. Furthermore, the optical fiber strand is preferably a plastic optical fiber strand. The optical fiber cord of the present invention is preferably used indoors or on the premises.

  According to the optical fiber cord of the present invention, the optical fiber and the first covering portion are arranged with a space therebetween, and these are connected by the second covering portion, and the second covering portion has two adjacent light beams. Since there is a portion on the plane that is perpendicular to the plane including the central axis of the fiber strand and thicker than the thickness on the line orthogonal to the central axis, it is bent when wiring or using the optical fiber cord. Even if an external force such as stepping or pressing is applied, a force is applied to the portion having a large thickness, and it is difficult to apply a force to the optical fiber strand and the first covering portion. It is possible to prevent the communication characteristics from being adversely affected. Further, if a tensile strength wire is provided in at least one region of the end portion of the second covering portion or the portion between the optical fiber strands, the processing of the tensile strength wire is simplified during the end processing of the optical fiber cord.

  If a groove for tearing the second covering portion was formed on the outer peripheral surface of the second covering portion in parallel to the axis of the optical fiber strand, the optical fiber cord was provided at the end treatment of the optical fiber cord. A 2nd coating | coated part and the 2nd coating | coated part with a tensile strength line can be torn easily, and a terminal process becomes simpler.

  The optical fiber cord of the present invention is, for example, a two-core optical fiber cord 2 as shown in FIG. The optical fiber cord 2 is used with an optical plug 3 connected to the end. Note that the optical fiber cord 2 is in a state in which terminal processing described later is performed. The optical plug 3 is detachable from other optical connectors (not shown) such as a receptacle or an adapter.

  The optical plug 3 includes a plug body 4, two ferrules 5, and a pressing member 6. The plug body 4 has a substantially rectangular parallelepiped shape. An insertion port 7 into which the optical fiber cord 2 is inserted is formed on one end face of the plug body 4. The ferrule 5 is made of synthetic resin and is formed in a cylindrical shape. The inner diameter of the cylinder is substantially the same as the outer diameter of the optical fiber 8 of the optical fiber cord 2. The optical fiber 8 will be described later. The ferrules 5 are arranged and fixed to the plug body 4 such that one end protrudes from the plug body 4. The interval between the ferrules 5 (the distance from the central axis of one ferrule 5 to the central axis of the other ferrule 5) is D1. Note that the ferrule 5 is not necessarily provided in the optical plug 3 as long as the optical fiber 8 can be accurately positioned.

  The position where the ferrule 5 is disposed is the optical coupling position in the optical plug 3. The optical coupling position means that when a predetermined optical connector is connected to another optical connector, an optical fiber in the predetermined optical connector can optically couple with an optical fiber or an optical component in the other optical connector. Position.

  The holding member 6 has a substantially U-shaped cross section, and a convex portion 9 is formed at the center in the width direction. The holding member 6 is provided with fixed claws 11 at both ends in the width direction. The pressing member 6 is inserted from the opening 10 on the upper surface of the plug body 4. The plug body 4 is provided with a guide wall 12 for guiding the presser member 6. When the pressing member 6 is inserted through the opening 10 and pushed in, the fixing claw 11 of the pressing member 6 engages with the groove 12 a of the guide wall 12 of the plug body 4. Thereby, it is possible to prevent the pressing member 6 from falling off the plug body. In addition, you may plant a fixing pin in the convex part 9, In this case, when the pressing member 6 is inserted in the plug main body 4, a fixing pin stabs in the connection part 21b of a 2nd coating | coated part, The optical fiber cord 2 is firmly fixed to the plug body 4.

  The optical fiber cord 2 has two optical fiber strands 8. The optical fiber strands 8 are arranged so as to be parallel to each other. The distance between the optical fiber strands 8 (the distance from the central axis of one optical fiber strand 8 to the central axis of the other optical fiber strand 8) is D2. Here, the interval between the optical fiber strands 8 is the same as the interval between the ferrules 5 of the optical plug 3, that is, “D2 = D1”. The positional error at this time is preferably in the range of −0.2 [mm] to +0.2 [mm], and is in the range of −0.1 [mm] to +0.1 [mm]. Is more preferable, and is more preferably within a range of −0.05 [mm] to +0.05 [mm].

  As shown in FIG. 2, which is a cross-sectional view of the optical fiber cord 2, the optical fiber 8 is composed of a core 17 through which light passes and a clad 18 that is an outer shell portion. The material constituting the optical fiber used in the present invention is not particularly limited because bending loss and microbending occur regardless of the material. In this example, a case where a plastic optical fiber which is easy to handle and is likely to be attached and detached is used will be described. The clad 18 has a tube shape with a uniform thickness. For the clad 18, for example, polyvinylidene fluoride (PVDF) is used as a material. For the clad 18, a polymer such as PVDF copolymer or PMMA may be used, or other materials may be used. A mixture of polymers may also be used. The core 17 may be composed of an inner inner core and an outer outer core having different refractive index application states. In that case, the outer core has a tubular shape with a uniform thickness, and the refractive index is higher than that of the clad 18. The inner core has a cylindrical shape with a uniform diameter. The refractive index of the inner core is the same as that of the outer core at the boundary with the outer core, and the refractive index increases from the boundary of the outer core toward the center. The diameter of the core 17 is not particularly limited, but is preferably in the range of 90 to 720 [μm]. For the core 17, for example, a polymer such as PMMA or a fluoropolymer is used as a material. Other materials may be used for the core 17. Furthermore, a coating | coated part can be provided in the outer side of a clad. As this coating | coated part, polymers, such as PMMA and PVDF, PVDF copolymer may be used, and another material may be used, for example.

  The optical fiber 8 is preferably a refractive index distribution type because the transmission band is large. In the case of a two-core optical fiber cord, a configuration in which one core is a GI type and the other core is an SI type (step index type) is also preferable depending on the purpose. The numerical aperture of the optical fiber 8 is not particularly limited, but is preferably 0.15 or more. More preferably, it is 0.20 or more as a numerical aperture, More preferably, it is 0.28 or more.

  A tensile strength wire 19 is disposed between the optical fiber strands 8. The tensile strength wire 19 is covered with a connecting portion 21b of a second covering portion 21 described later. The amount of the tensile wire 19 can be reduced by arranging the tensile wire 19 between the optical fiber wires 8 instead of arranging the tensile wire 19 along the outer periphery of the optical fiber wire 8. For the tensile strength wire 19, FRP (Fiber Reinforced Plastic) in which an aramid fiber is coated with a resin is used. In addition to FRP, a steel wire such as a piano wire, a single wire of other metal, a stranded wire, a glass fiber, or the like may be used for the tensile strength wire 19. In this example, the description is made with a two-fiber optical fiber cord. However, in the case of a multi-fiber optical fiber cord, there is no need to arrange a tensile wire between all the optical fiber strands, and the mechanical strength. In consideration of the above, it is only necessary to arrange the tensile strength line only in a necessary area. In this example, the tensile strength wire is disposed between the optical fiber strands, but the tensile strength wire may be disposed further outside the outermost optical fiber strand, that is, at the end of the second covering portion. Further, in this example, the description is made with the optical fiber cord having the tensile line, but the tensile line may not be provided.

  The optical fiber 8 is covered with the first covering portion 20 and further covered with the second covering portion 21. The first covering portion 20 has a tube shape with a uniform thickness, and the inner peripheral surface is in close contact with the optical fiber 8. For example, polyethylene colored black is used as the material for the first covering portion 20. For the first covering portion 20, vinyl chloride, polyurethane, polyamide or the like may be used as a material, or other materials may be used.

  The 2nd coating | coated part 21 has the strand part 21a which covers the optical fiber strand 8 and the 1st coating | coated part 20, and the connection part (part with large thickness) 21b which connects the optical fiber strand 8 and the 1st coating | coated part 20 mutually. It consists of and. The strand portion 21 a is in close contact with the outer peripheral surface of the first covering portion 20. The strand portion 21 a has a flat upper surface and a lower surface, and a side surface away from the tensile strength wire 19 is a curved surface having a constant curvature. The thickness of the outer circumference of the strand portion 21a (the distance from the upper surface to the lower surface on a line perpendicular to the plane including the central axis 15 of the two optical fiber strands 8 and perpendicular to the central axis 15 of the optical fiber strand 8) ) Is D3.

  The connecting portion 21 b is in close contact with the outer peripheral surface of the tensile strength wire 19. The connecting portion 21b has a flat upper surface and lower surface. The thickness of the outer periphery of the connecting portion 21b (the distance from the upper surface to the lower surface on the line perpendicular to the plane including the central axis 15 of the two optical fiber wires 8 and perpendicular to the central axis 16 of the tensile strength wire 19) is D4. It is. Note that the tensile strength wire 19 may be coated and processed to be thick to improve handling, and this may be covered with the connecting portion of the second covering portion. In this case, the covering portion that directly covers the tensile strength wire 19 and the connecting portion of the second covering portion can be considered. Thus, the 2nd coating | coated part may consist of a multilayer.

  In the optical fiber cord 2 of the present invention, “D4> D3” is always established. In the upper part or the lower part of the optical fiber cord 2, the difference between the thickness of the strand portion 21a and the thickness of the connecting portion 21b is D5. The difference in thickness between the outer periphery of the strand portion 21a and the outer periphery of the connecting portion 21b is “D5 + D5”. The value of D5 is not particularly limited, but is preferably in the range of 0.1 [mm] to 0.5 [mm], and preferably in the range of 0.2 [mm] to 0.3 [mm]. Is more preferable. As described above, the outer peripheral thickness D4 of the connecting portion 21b of the second covering portion 21 is set to be larger than the outer peripheral thickness D3 of the strand portion 21a of the second covering portion 21.

  As can be seen from the above, the connecting portion 21b of the second covering portion 21 is thicker than the thickness on a line perpendicular to the plane including the central axis 15 of the two adjacent optical fibers 8 and orthogonal to the central axis 15. It is a site | part, and the site | part with this thick thickness is arrange | positioned on the said plane.

  Two triangular grooves 22 are formed on each of the upper surface and the lower surface of the second covering portion 21. The groove 22 is formed parallel to the axes of the optical fiber strand 8 and the tensile strength wire 19 between the strand portion 21a and the connecting portion 21b. These grooves 22 are for easily tearing when the optical fiber 8 and the tensile strength wire 19 are separated. The shape of the groove 22 is not limited to this. Moreover, the groove | channel 22 may be formed only in one surface among an upper surface or a lower surface, and does not need to be formed when it is not required. For the second covering portion 21, for example, vinyl chloride is used as a material. For the second covering portion 21, polyethylene, polyurethane, polyamide, or the like may be used as a material, or other materials may be used.

  The specific size of the optical fiber cord 2 is, for example, as follows. In order to correspond to the SMI type optical plug, the distance D2 between the optical fiber strands 8 is set to 5 [mm]. For example, the diameter of the core 17 is 316 [μm], the diameter of the tensile strength wire 19 is 0.45 [mm], the outer diameter of the first covering portion 20 is 1.2 [mm], and the strand of the second covering portion 21 The thickness D3 of the portion 21a is 2.2 [mm], and the thickness D4 of the connecting portion 21b of the second covering portion 21 is 2.8 [mm] (at this time, the thickness difference D5 is 0.3 [mm]).

  Further, in the case of corresponding to the PN type optical plug or the F07 type optical plug, the distance D2 between the optical fiber strands 8 is set to 10.16 [mm]. In order to correspond to the LC type optical plug, the distance D2 between the optical fiber strands 8 is set to 6.25 [mm]. Of course, the size of each part is not limited to the above.

  The optical fiber cord 2 is manufactured through a process of manufacturing the optical fiber 8 and a process of coating the manufactured optical fiber 8. In the process of manufacturing the optical fiber 8, after manufacturing the preform, the preform is stretched by heating and melting to form a fiber. The manufactured optical fiber 8 is wound around a bobbin (not shown).

  In the step of coating the optical fiber strand 8, first, the optical fiber strand 8 is pulled out from the bobbin, and two optical fiber strands 8 are arranged and conveyed to a first coating device (not shown). The first coating apparatus includes an extruder having a circular extrusion section, and the two optical fiber strands 8 are extruded in a state covered with the first coating section 20. The two optical fiber strands 8 covered with the first covering portion 20 are transported together with the tensile strength wire 19 to a second covering device (not shown). The second coating apparatus is provided with an extruder having an extrusion portion having the outer shape shown in FIG. 2, and includes two optical fiber strands 8 covered with the first coating portion 20 and a tensile strength wire. 19 is extruded while being covered with the second covering portion 21. This is cooled to become the optical fiber cord 2.

  In the above description, when covering the second covering portion 21, the strand portion 21a and the connecting portion 21b are covered together, but the strand portion 21a and the connecting portion 21b are separately manufactured and welded. You may let them. Here, the strand portion 21 a is welded while covering the optical fiber strand 8 and the first covering portion 20. The connecting portion 21 b is preferably welded in a state of covering the tensile strength wire 19, but may not have the tensile strength wire 19.

  In addition, regarding manufacture of the optical fiber cord 2, it is not restricted to said manufacturing method. For example, in the process of manufacturing the optical fiber 8, the material may be made into a fiber by a co-extrusion method without using a preform.

  In the case of the optical fiber cord 2 as described above, when the optical fiber cord 2 is passed through a pipe such as a CD pipe or a duct installed indoors or on the premises, the outer periphery of the second covering portion 21. A force is applied to the connecting portion 21b whose thickness is increased, and no large force is applied to the strand portion 21a. Thereby, it can prevent that the strand 21a of the 2nd coating | coated part 21 and the 1st coating | coated part 20 deform | transform, and the fall of the communication characteristic by the deformation | transformation of the optical fiber strand 8 is suppressed.

  Below, the connection operation | work which connects the optical plug 3 and the optical fiber cord 2 is demonstrated using FIG.1 and FIG.3. In the connection work, first, terminal processing of the optical fiber cord 2 is performed.

  In the terminal processing, first, at the end of the optical fiber cord 2, the second covering portion 21 is torn in the axial direction to be separated into the strand portion 21a and the connecting portion 21b, and the portion having the optical fiber strand 8; It isolate | separates into the part which has the tensile strength line 19. FIG. Here, since the groove | channel 22 is formed in the 2nd coating | coated part 21, it can tear easily. For the portion having the optical fiber 8, the coating layers 20 and 21 are peeled off by a predetermined length using a stripper (not shown), so that the optical fiber 8 is partially exposed. A portion having the tensile strength line 19 is cut by a predetermined length using a cutter (not shown). Here, the tensile wire 19 is arranged alone without being wound around the optical fiber 8, and the second covering portion 21 is in close contact with the tensile wire 19, so that it is easily cut. be able to. Although FIG. 1 shows an example in which the tensile strength wire 19 is cut, there may be a method in which the tensile strength wire 19 is taken out from the cord coating and fixed to the optical plug 3.

  The optical fiber cord 2 subjected to terminal processing is inserted from the insertion port 7 into the optical plug 3 with the pressing member 6 removed. The partially exposed optical fiber 8 is passed through the ferrule 5, and the optical fiber cord 2 is inserted so that the tip of the optical fiber 8 protrudes slightly from the end of the ferrule 5. Here, since the interval D2 between the optical fiber strands 8 is the same as the interval D1 between the ferrules 5, the optical fiber cord 2 is inserted while keeping the optical fiber strands 8 parallel to each other. For this reason, it is not necessary to widen the space | interval of the optical fiber strand 8 in particular, and a curvature does not arise in the optical fiber strand 8. FIG. Although not shown in this example, it is also preferable that the insertion port 7 is provided with a guide having a shape corresponding to the groove 22 of the optical fiber cord 2.

  After the optical fiber cord 2 is inserted into the optical plug 3 to a predetermined position, the pressing member 6 is inserted from the opening 10. A convex portion 9 is formed at the center portion in the width direction of the pressing member 6, and the convex portion 9 is in pressure contact with the connecting portion 21 b of the second covering portion 21 of the optical fiber cord 2. Thereby, the optical fiber cord 2 is fixed to the optical plug 3 without applying a force to the optical fiber strand 8, and the optical fiber cord 2 and the optical plug 3 are connected. Although not shown in this example, the pressing member 6 may be provided with a metal claw for fixing the connecting portion 21b, a hole for pouring an adhesive, or the like.

  Next, end face processing is performed on the optical fiber cord 2. When the optical fiber 8 is a plastic optical fiber, a hot plate heater (not shown) is used. Below, the case of a plastic optical fiber strand is illustrated. The optical fiber cord 2 is pressed together with the optical plug 3 to the heating surface of the hot plate heater. The optical fiber 8 protruding slightly from the end face of the ferrule 5 is melted and deformed, and the end face of the optical fiber 8 is made smooth.

  Thus, as shown in FIG. 3, the connection work between the optical fiber cord 2 and the optical plug 3 is completed. If this optical plug 3 is connected to another optical connector, the optical fiber 8 and the optical fiber or optical component in the other optical connector can be optically coupled. Since the distance D2 of the optical fiber 8 and the distance D1 of the ferrule 5 are the same, the optical fiber cord 2 and the optical plug 3 can be connected without bending the optical fiber 8. It is possible to prevent an increase in transmission loss of the optical fiber 8 and deterioration of the transmission band.

  Instead of the optical fiber cord 2 described in the above embodiment, a two-core optical fiber cord 30 having a cross section shown in FIG. 4 may be used. In this case, the outer shape in the cross section of the second covering portion 31 is an elliptical shape. The ellipse has the thickest outer periphery above and below the tensile strength line 19. In addition, you may form a groove | channel between the optical fiber strand 8 and the tensile strength wire 19 similarly to embodiment shown in FIG.

  Instead of the optical fiber cord 2 described in the above embodiment, a two-core optical fiber cord 40 having a cross section shown in FIG. 5 may be used. The second covering portion 41 includes a strand portion 41 a that covers the optical fiber 8 and the first covering portion 20, and a connecting portion (a portion having a large thickness) 41 b that covers the tensile strength wire 19. The external shape in the cross section of the strand part 41a is circular. Moreover, the external shape in the cross section of the connection part 41b is hexagonal shape. In the direction perpendicular to the plane including the central axis 15 of the adjacent optical fiber 8, the outer periphery of the connecting portion 41 b is thicker than the outer periphery of the strand. When the optical fiber cord 40 is manufactured, a manufacturing method is employed in which the outer peripheral surface of the strand portion 41a and the outer peripheral surface of the connecting portion 41b are joined. You may take the manufacturing method which shape | molds the strand part 41a and the connection part 41b integrally.

  Moreover, the optical fiber cord 50 of the 2 core of the cross section shown in FIG. 6 may be sufficient. The 2nd coating | coated part 51 is comprised from the strand part 51a and the connection part (part with large thickness) 51b. The outer shape of the cross section of the connecting portion 51b is circular. A two-fiber optical fiber cord 60 having a cross section shown in FIG. 7 may be used. The 2nd coating | coated part 61 is comprised from the strand part 61a and the connection part (site | part with large thickness) 61b. The outer shape of the cross section of the connecting portion 61b is trapezoidal.

  In the embodiment described above, a two-fiber optical fiber cord is used. However, a multi-fiber optical fiber cord having three or more fibers may be used. For example, a four-fiber optical fiber cord 70 having a cross section shown in FIG. 8 may be used. The optical fiber cord 70 has four optical fiber strands 8 arranged in parallel to each other. The second covering portion 71 includes a strand portion 71 a that covers the optical fiber 8 and the first covering portion 20, and a connecting portion (a portion having a large thickness) 71 b that covers the tensile strength wire 19. In the direction perpendicular to the plane including the central axis 15 of the adjacent optical fiber 8, the outer periphery of the connecting portion 71 b is thicker than the outer periphery of the strand 71 a. In addition, it is not necessary to make the thickness of all the connection parts thicker than the thickness of the strand part, and you may make only the thickness of arbitrary connection parts thick.

  A two-fiber optical fiber cord 80 having a cross section shown in FIG. 9 may be used. The 2nd coating | coated part 81 is comprised from the strand part 81a and the connection part 81b. The strand portion 81a is a region within the range indicated by the dotted line in FIG. 9, and the connecting portion 81b is a region outside the range indicated by the dotted line in FIG. As shown in FIG. 9, in the direction perpendicular to the plane including the central axis 15 of the adjacent optical fiber 8, the thickness of the outer periphery of the connecting portion 81 b disposed further outside the optical fiber 8 is It is made thicker than the thickness of the outer periphery of the part 81a. In the present example, the connecting portion 81b disposed on the further outer side of the optical fiber 8 is defined as “a portion having a large thickness”.

  In the case of a multi-core optical fiber cord, the optical fiber cord 90 having a cross section shown in FIG. 10 may be used. In this way, the optical fiber wires 8 may be arranged three-dimensionally. The second covering portion 91 includes a strand portion 91a within the range indicated by the dotted line in FIG. 10 and a connecting portion 91b outside the range indicated by the dotted line. When the optical fiber strands 8 are three-dimensionally arranged, the outer periphery of the connecting portion 91b on the side in contact with the object or the like in the direction perpendicular to the plane including the central axis 15 of the adjacent optical fiber strands 8 is provided. The thickness should just be thicker than the thickness of the strand part 91a. In this example, the connecting portion 91b disposed further outside the optical fiber 8 is defined as “a portion having a large thickness”. In the case of a multi-fiber optical fiber cord, it is preferable that all the optical fiber strands are arranged on substantially the same plane from the viewpoint of handleability.

  In the above embodiment, a refractive index distribution type (GI type) POF made of plastic is used for the optical fiber, but for example, an SI type POF, a quartz optical fiber, a plastic clad fiber (PCF), or the like. However, it may be more preferably applied when used for a plastic optical fiber that generally has a large wire diameter and a relatively small thickness of the second covering portion. it can. In addition, not only the multi-mode but also the single mode can be used.

1 is an external perspective view of an optical fiber cord and an optical plug according to the present invention. It is sectional drawing of the optical fiber cord in the cut surface which follows the II-II line | wire of FIG. It is a top view of the optical fiber cord with which the optical plug was attached. It is sectional drawing of the optical fiber cord of another embodiment by which the external shape in the cross section of the 2nd coating | coated part was made into elliptical shape. It is sectional drawing of the optical fiber cord of another embodiment by which the external shape in the cross section of the connection part of a 2nd coating | coated part was made into hexagonal shape. It is sectional drawing of the optical fiber cord of another embodiment by which the external shape in the cross section of the connection part of a 2nd coating | coated part was made into circular shape. It is sectional drawing of the optical fiber cord of another embodiment by which the external shape in the cross section of the connection part of a 2nd coating | coated part was made into trapezoid. It is sectional drawing of the optical fiber cord of another embodiment with four optical fiber strands. It is sectional drawing of the optical fiber cord of another embodiment by which the external shape of the 2nd coating | coated part was made into H shape. It is sectional drawing of the optical fiber cord of another embodiment when an optical fiber strand is arrange | positioned in three dimensions. It is sectional drawing of the conventional optical fiber cord.

Explanation of symbols

2, 30, 40, 50, 60, 70, 80, 90 Optical fiber cord 8 Optical fiber strand 15 Central axis 19 Tensile wire 20 First covering portion 21, 31, 41, 51, 61, 71, 81, 91 First 2 coating | cover part 21a, 41a, 51a, 61a, 71a, 81a, 91a Wire part 21b, 41b, 51b, 61b, 71b, 81b, 91b Connecting part 22 Groove

Claims (11)

In an optical fiber cord comprising an optical fiber, a first covering that covers the optical fiber, and a second covering that covers a plurality of the first coverings,
The optical fiber and the first covering portion are arranged at intervals, and these are connected by the second covering portion,
The second covering portion has a portion on the plane that is perpendicular to a plane including the central axis of two adjacent optical fiber strands and is thicker than a thickness on a line orthogonal to the central axis. A featured optical fiber cord.   A tensile strength wire is provided in at least one region of an end portion of the second covering portion or a portion between the optical fiber strands, and the tensile strength wire is disposed so as to be covered by the second covering portion. The optical fiber cord according to claim 1.   The optical fiber cord according to claim 1, wherein the first covering portion is in close contact with the optical fiber.   The groove | channel for tearing the said 2nd coating | coated part is formed in the outer peripheral surface of the said 2nd coating | coated part in parallel with the axis | shaft of the said optical fiber strand, The any one of Claim 1 thru | or 3 characterized by the above-mentioned. An optical fiber cord according to the item.   The optical fiber cord according to any one of claims 1 to 4, wherein the number of the optical fiber strands is two.   5. The optical fiber cord according to claim 1, wherein the optical fiber cord has three or more optical fiber strands, and these optical fiber strands are arranged on substantially the same plane.   The optical fiber cord according to any one of claims 1 to 6, wherein at least one of the optical fiber strands has a numerical aperture of 0.15 or more.   The optical fiber cord according to any one of claims 1 to 7, wherein at least one of the optical fiber strands has a core diameter in a range of 90 to 650 µm.   The optical fiber cord according to any one of claims 1 to 8, wherein at least one of the optical fiber strands is a multimode optical fiber strand.   The optical fiber cord according to any one of claims 1 to 9, wherein at least one of the optical fiber strands is a gradient index optical fiber strand. The optical fiber cord according to any one of claims 1 to 10, wherein at least one of the optical fiber strands is a plastic optical fiber strand.

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