JP5193015B2 - Slot type optical cable - Google Patents

Description

  The present invention relates to a slot type optical cable.

  The slot-type optical cable includes a slot rod having a plurality of grooves (hereinafter referred to as storage grooves) that extend along the axial direction and are radially formed in a cross-section, and an optical fiber that is stored in each storage groove. The cover tape is wound around the outer periphery of the slot rod in which the optical fiber is accommodated, and the sheath accommodates the entire slot rod in which the cover tape is wound. The optical fiber accommodates, for example, a tape core formed by integrating a plurality of optical fibers with a resin and formed into a tape shape, or an optical fiber single core.

As the shape of the slot for storing the slot rod, there are two types, an S type formed in a spiral shape in one direction in the longitudinal direction of the slot rod, and an SZ type in which the spiral direction is reversed at a predetermined length. The SZ type can be easily pulled out from the storage groove in the middle of the slot-type optical cable, and is suitable for intermediate post branching work.
The partitions between the storage grooves are generally called ribs.

  At the time of manufacturing the slot type optical cable, the covering tape is wound around the slot rod in which the optical fiber is accommodated in the accommodation groove. Thereafter, a sheath is formed by extrusion-coating a high-temperature thermoplastic resin on the outside of the coating tape.

By the way, in the optical fiber branch connection work, it is necessary to remove the sheath over several tens of centimeters in the vicinity of the slot type optical cable terminal or the position where the intermediate optical fiber branch connection is performed.
As described above, the slot-type optical cable has a structure in which a coating tape is wound around the outer periphery of the slot rod in a state where the optical fiber is housed in the housing groove, and a sheath is coated on the outer side. Therefore, the operator needs to cut the sheath and the covering tape with a blade etc., and since it is necessary to pay close attention not to damage the tape core wire at this time, the workability is poor. It was.
As a technique for solving this, a structure has been proposed in which a notch is provided at a position corresponding to the rib of the sheath so that the sheath is easily torn (for example, see Patent Document 1).
JP 2006-3774 A

  However, in the structure in which the notch is provided in the sheath as described in Patent Document 1, the sheath is stretched or compressed and contracted due to the difference in circumferential length when the cable is wound around the drum, and the bending, twisting, and friction when the cable is laid. The sheath may be torn by external force such as. If the sheath is torn, water may enter the cable or external force may be applied directly to the optical fiber, leading to deterioration of the optical fiber characteristics, and in some cases, the optical fiber may be broken. is there.

  The present invention has been made in view of the above, and it is an object of the present invention to provide a slot-type optical cable that can easily perform branch connection of an optical fiber without damaging the optical fiber and maintain reliability.

In order to solve the above problems, the invention according to claim 1 of the present invention is a slot-type optical cable, wherein a slot rod having a plurality of storage grooves and ribs partitioning the storage grooves formed on an outer peripheral portion; An optical fiber housed in the housing groove; a covering tape that covers an outer periphery of the rod rod; and a sheath provided on the outer periphery of the covering tape, the sheath including the housing groove At least one protrusion is provided on the outer peripheral portion at a position corresponding to the rib partitioning, and the end portion on the outer peripheral side of the rib corresponding to the protrusion and the covering tape provided on the rib are disposed in the protrusion. And the thickness of the rib in the line position which ties the both ends of the base end side of the said protrusion on the cross sectional view is 2 mm or less, It is characterized by the above-mentioned.

The invention according to claim 2 is a slot-type optical cable, wherein a slot rod in which a plurality of storage grooves and ribs for partitioning the storage groove are formed on an outer periphery, an optical fiber stored in the storage groove, A sheath provided on the outer periphery of the rod rod, and the sheath is provided with at least one protrusion on the outer periphery corresponding to the rib partitioning the storage groove, and corresponds to the protrusion An end portion on the outer peripheral side of the rib is arranged in the protrusion, and the thickness of the rib at a line position connecting both ends on the proximal end side of the protrusion in a cross-sectional view is 2 mm or less .

  A third aspect of the present invention is the slot-type cable according to the first or second aspect, wherein the rib has an outer width smaller than the center-side width in the cross section in the cross section. To do.

  According to the present invention, it is possible to provide a slot-type optical cable that can easily perform branch connection work of an optical fiber without damaging the optical fiber and that maintains reliability.

Hereinafter, the present invention will be described in detail.
FIG. 1 is a sectional view of a slot-type optical cable 1 according to the first embodiment of the present invention. As shown in FIG. 1, the slot-type optical cable 1 is generally composed of a slot rod 10, a tape core wire 20, a covering tape 40, and a sheath 60.

A tension member 11 that bears tension is disposed at the center of the slot rod 10. The tension member 11 is a tensile member such as a single steel wire, a twisted steel wire, glass fiber, or aramid fiber.
The portion of the slot rod 10 outside the tension member 11 is made of a thermoplastic resin such as linear low density polyethylene, low density polyethylene, medium density polyethylene, high density polyethylene, polyamide resin, engineering plastic or the like. Among these, it is preferable to use high-density polyethylene from the viewpoint of price, manufacturability, and use results.

Further, the outer periphery of the slot rod 10 is provided with a plurality of storage grooves 12 extending in the longitudinal direction at intervals in the circumferential direction of the slot rod 10 and ribs 13 partitioning the storage grooves 12. Then, four ribs 13 are provided. The shape of the storage groove 12 may be an S shape formed in a spiral shape in one direction in the longitudinal direction of the slot rod 10 or an SZ shape in which the spiral direction is reversed at a predetermined length.
In the storage groove 12, tape core wires 20 in which a plurality of optical fibers are arranged in a line are stored. In addition, you may accommodate the single core wire of an optical fiber.

  As shown in FIG. 1, the rib is formed such that the width of the tip side (outside of the slot type optical cable 1) is smaller than the width of the root side (center side of the slot type optical cable 1) in the cross section.

The covering tape 40 is pressed and wound around the outside of the slot rod 10 in a state where the tape core wire 20 is housed in the housing groove 12. With the covering tape 40, the tape core wire 20 stored in the storage groove 12 is fixed so as not to jump out before the sheath 60 is formed. Also. The covering tape 40 can prevent the thermoplastic resin forming the sheath 60 from entering the storage groove 12.
Examples of the covering tape 40 include films and nonwoven fabric tapes using thermoplastic resins such as linear low density polyethylene, low density polyethylene, medium density polyethylene, high density polyethylene, polyamide resin, polypropylene, polyethylene terephthalate, and engineering plastic. Is used as appropriate.
The covering tape 40 is provided with a measure such as pressing with an intermittent filler so that the optical fiber single fiber or the optical fiber 20 stored in the storage groove 12 does not move before the sheath 60 is formed. It can be omitted if it is.

  A sheath 60 is provided outside the covering tape 40. A thermoplastic resin can be used for the sheath 60. As such a thermoplastic resin, for example, vinyl chloride resin, linear low density polyethylene, low density polyethylene, medium density polyethylene, high density polyethylene, polyamide resin, engineering plastic, and the like can be used. Among these, it is preferable to use linear low density polyethylene, low density polyethylene, and high density polyethylene from the viewpoint of cost and manufacturability.

In addition, when it is necessary to consider flame retardancy in particular, blending organic and inorganic flame retardants and flame retardant aids with ethylene-ethyl acrylate (EEA), ethylene vinyl acetate (EVA), etc. as the base resin In addition, those obtained by further improving the flame retardancy of vinyl chloride resins, vinyl chloride resins, and the like can be used.
In consideration of the outdoor installation environment, carbon black, an antioxidant, an ultraviolet ray inhibitor, an absorbent, a color pigment, and the like can be appropriately blended.

  FIG. 2 is an enlarged view of a portion II in FIG. In the present embodiment, as shown in FIG. 2, a protrusion 61 extending along a position corresponding to the rib 13 is provided on the outer peripheral portion of the sheath 60, and the tip of the rib 13 is the protrusion 61. It extends to the inside. That is, as shown in FIG. 2, in the cross section, the rib 13 is extended to the outside of the alternate long and short dash line L <b> 1 that connects both ends of the protrusion 61. In addition, since the thickness of the sheath 60 in the portion of the protrusion 61 is substantially the same as that of the other portions, it can sufficiently withstand the wear and the like when the cable is laid.

  L1 is a line connecting the intersections P1 and P1 between the perfect circle closest to the outer periphery of the sheath 60 and the protrusion 61.

  In order to take out the optical fiber in the branch connection work, a blade (not shown) is put in the protrusion 61 along the one-dot chain line L1 in FIG. At this time, the cutting edge of the blade is always in a parallel state with respect to the optical fiber single fiber or the tape fiber 20 stored in the storage groove 12. As a result, the end of the rib 13 can be cut in the longitudinal direction of the cable without damaging the optical fiber, and the covering tape 40 and the sheath 60 are torn.

  Even if the ridge 61 is removed along the alternate long and short dash line L1, the storage groove 12 is not exposed and is covered with the covering tape 40 and the sheath 60, so that the optical fiber stored in the storage groove 12 may be damaged. There is no. Thereafter, the covering tape 40 and the sheath 60 can be easily taken out from the cutting part without damaging the tape core wire 20, for example, by manually opening without using a tool.

  In addition, since the rib 13 consists of a hard material, when the length which cuts the rib 13 with a cutter becomes long, it will become difficult to cut along the dashed-dotted line L1. For this reason, in FIG. 2, it is preferable that the thickness of the rib 13 of the part cut | disconnected in the dashed-dotted line L1 is 2 mm or less. If it is 2 mm or less, the ridge 61 can be torn without requiring a large force. For this reason, it is preferable that the width of the rib on the outer side of the slot type optical cable 1 is smaller than the width on the center side in the cross section of the slot type optical cable 1.

  Moreover, as shown in FIG. 3, it is good also as a structure by which only the coating tape 40 is extended inside the protrusion 61. FIG. In this case, the covering tape 40 and the sheath 60 are torn by inserting a blade into the protrusion 61 along the alternate long and short dash line L1. Even if the covering tape 40 is not completely torn with the blade, the portion of the covering tape 40 containing the blade is weak in strength, and can be torn by hand. The tape core wire 20 can be easily taken out as in the case where the tape 61 is extended to the inside of the ridge 61.

The present invention is not limited to the above embodiment, and various improvements and design changes may be made without departing from the spirit of the present invention.
For example, as shown in FIG. 4, the sheath 60 may be provided directly outside the slot rod 10 without providing the covering tape 40. In this case, for example, a measure such as pressing with an intermittent filler may be taken so that the single fiber core or the tape core 20 of the optical fiber stored in the storage groove 12 does not move before the sheath 60 is formed. Further, the shape of the storage groove 12 is not limited to the wedge shape as shown in FIG. 1, and the bottom portion may be flat.

  In FIG. 1, the protrusions 61 extending along the positions corresponding to all the ribs 13 are provided. However, the protrusions 61 extending along at least one or more ribs 13 </ b> A may be provided. That's fine. For example, as shown in FIG. 5, two protrusions 61 extending along any two ribs 13 may be provided. In FIG. 5, the tips of the ribs 13 corresponding to the insides of the two ridges 61 are extended.

  The tip shape of the rib 13 can also be changed as appropriate by the extrusion processing of the slot rod 10. 1 and 2, the tip section has an acute angle. However, as shown in FIG. 6, the tip has a rounded tip shape, and the tip of the rib 13 cut by the alternate long and short dash line L1 has a semicircular section. It may be. Alternatively, as shown in FIG. 7, the tip shape may be reduced in corners, and the shape of the tip cut by the alternate long and short dash line L <b> 1 may be a square in cross section.

  Alternatively, as shown in FIG. 8, a constriction 14 may be provided at a portion cut by the one-dot chain line L1 of the rib 13 so that the shape of the tip cut by the one-dot chain line L1 has a substantially circular cross section. By providing the constriction 14, the rib 13 can be easily cut along the constriction 14.

It is a schematic sectional drawing which shows one Embodiment of the optical fiber cable of this invention. It is an enlarged view of the II section of FIG. It is a schematic sectional drawing which shows one Embodiment of the optical fiber cable of this invention. It is a schematic sectional drawing which shows one Embodiment of the optical fiber cable of this invention. It is a schematic sectional drawing which shows one Embodiment of the optical fiber cable of this invention. It is a schematic sectional drawing which shows one Embodiment of the optical fiber cable of this invention. It is a schematic sectional drawing which shows one Embodiment of the optical fiber cable of this invention. It is a schematic sectional drawing which shows one Embodiment of the optical fiber cable of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Slot type optical cable 10 Slot rod 12 Storage groove 13 Rib 20 Tape core wire (optical fiber)
40 covering tape 60 sheath 61 ridge

Claims (3)

A slot rod in which a plurality of storage grooves and ribs for partitioning the storage grooves are formed on the outer periphery;
An optical fiber housed in the housing groove;
A covering tape covering the outer periphery of the rod rod;
A sheath provided on the outer periphery of the covering tape,
The sheath is provided with at least one protrusion on the outer peripheral portion at a position corresponding to the rib partitioning the storage groove,
The rib at the line position connecting the both ends on the base end side of the ridge in a cross-sectional view, the end on the outer peripheral side of the rib corresponding to the ridge and the covering tape provided on the rib are arranged in the ridge The slot type optical cable is characterized in that the thickness of the slot is 2 mm or less . A slot rod in which a plurality of storage grooves and ribs for partitioning the storage grooves are formed on the outer periphery;
An optical fiber housed in the housing groove;
A sheath provided on the outer periphery of the rod rod,
The sheath is provided with at least one protrusion on the outer peripheral portion at a position corresponding to the rib partitioning the storage groove,
An end portion on the outer peripheral side of the rib corresponding to the protrusion is disposed in the protrusion, and the thickness of the rib at a line position connecting both ends on the base end side of the protrusion in a cross-sectional view is 2 mm or less. Characteristic slot type optical cable.   The slot-type optical cable according to claim 1 or 2, wherein the rib has an outer width smaller than a center-side width in a cross-section.

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