JP5149343B2 - Optical drop cable - Google Patents

Description

  The present invention relates to an optical drop cable used for drawing and wiring from a wiring system cable to a subscriber's house such as a building or a general house, and more particularly to an optical drop cable having a coating excellent in damage resistance.

  With the spread of communication services such as the Internet, FTTH (Fiber To The Home), which connects all sections from a telecommunications carrier to a subscriber's home with optical fiber, is rapidly expanding. In such FTTH, the optical wiring network in the vicinity of the subscriber's house is generally an overhead wiring using a power pole, and the main method is to drop the wiring cable from the wiring pole to the subscriber's house using an optical drop cable. Has been adopted.

  In general, this optical drop cable has a tensile body placed above and below an optical fiber core, a support wire is further placed thereon, and a thermoplastic resin such as polyethylene is collectively coated on the outer periphery thereof. It has a structure with a jacket. A connecting portion (neck portion) is provided between the cable support wire and the tensile body to facilitate separation from the cable support wire portion, and on both side surfaces of the cable jacket, A tearing notch is provided to facilitate removal of the optical fiber.

  By the way, recently, many damages due to cicada have been reported in the optical drop cable, and countermeasures have become an urgent issue. The damage is mainly due to the bearfish, which causes damage to the optical transmission as a result of damaging the optical fiber by piercing the egg drop tube into the optical drop cable.

  Therefore, in order to prevent damage to the optical fiber due to the oviposition tube of the bearfish, for example, a protective member that protects the optical fiber core is embedded in the jacket, or the tip of the tear notch is shifted from the position of the optical fiber core. In the unlikely event that an optical fiber core wire is not damaged even if a spawning tube of a bearfish is pierced into the notch, there have been proposed various measures taken on the cable structure itself (for example, Patent Documents 1 and 2). reference.). In addition, it has also been proposed that the outer cover is made of a resin having a specific rebound resilience and wear resistance, for example, and the structure itself is not changed, but the outer shell material is changed to give damage resistance. (For example, refer to Patent Document 3).

  However, in the case where the protective member is embedded, the take-out performance of the optical fiber core wire is lowered, and the number of parts is increased, so that the manufacturing cost is increased. In addition, shifting the position of the tip of the notch does not necessarily have an effect of preventing damage caused by the oviposition tube of the bearfish. On the other hand, the one using a specific resin for the jacket material is not sufficient for taking out the optical fiber core wire.

  In such a situation, the present inventors use a polyolefin resin having specific physical properties for the jacket material in order to achieve both damage resistance and core take-out property, and semi-fused to the jacket surface. An optical drop cable with a slit-shaped notch was developed.

  However, although such an optical drop cable achieves both damage resistance and core take-out performance as compared with the prior art, there is still room for improvement in terms of core take-out performance. When a tape-shaped optical fiber core wire (optical fiber tape core wire) is used as the core wire, the core wire takeout property is insufficient.

JP 2007-72380 A JP 2008-203797 A JP 2009-271538 A

  The present invention has been made in response to the above-described problems of the prior art, and can dramatically improve the take-out property of the optical fiber core of the tape-like optical fiber, and has an extremely high damage resistance. The purpose is to provide.

In order to achieve the above object, an optical drop cable according to claim 1 of the present application includes: an optical fiber ribbon; and tensile bodies arranged in parallel at intervals on both sides of the optical fiber ribbon; An optical drop cable having a jacket for covering them all together, wherein the jacket is formed of a polyolefin resin having a Shore D hardness (JIS K 7215) of 56 or more and 62 or less, and the jacket is the light Provided only on the surface in contact with the side surface parallel to the major axis direction of the fiber tape core wire is a gap portion that makes the outer cover and the optical fiber tape core wire not in close contact with each other, and a pair of tips is provided on the surface of the jacket. A slit-shaped notch in a semi-fused state reaching the vicinity of the gap is provided, and the ratio a between the width a of the gap in the major axis direction of the optical fiber ribbon and the major axis b of the optical fiber ribbon / B Is not less than 1/2 and not more than 3/4, and the adhesion of the optical fiber ribbon to the jacket (wherein the adhesion is exposed from the jacket leaving a length of 10 mm) The pulling force when pulling one end of the tape core wire at a pulling speed of 20 mm / min is 20N or more and 55N or less, and the tearing force starting from each slit-shaped notch is 12N or less. It is characterized by this.

An optical drop cable according to a second aspect of the present invention includes an optical fiber ribbon, tensile strength members arranged in parallel at intervals on both sides of the optical fiber ribbon, and a jacket covering them all at once. An optical drop cable having a cable portion provided and a support wire portion provided with a support wire for supporting the cable portion, wherein the jacket has a Shore D hardness (JIS K 7215) of 56 or more and 62 or less. A gap is formed with a polyolefin resin, and the outer jacket and the optical fiber ribbon are not in close contact with each other only on the surface where the outer jacket is in contact with the side surface parallel to the longitudinal direction of the optical fiber ribbon. A pair of slit-shaped notches in a semi-fused state in which a pair of leading ends reach the vicinity of the gap, and a width a in the major axis direction of the optical fiber ribbon, The ratio a / b of the major axis b of the optical fiber ribbon is, is 1/2 or more 3/4, adhesion to the said outer of said optical fiber ribbons (where adhesion is long 10N is the force required to pull out one end of the optical fiber ribbon that is exposed from the jacket leaving 10 mm at a pulling speed of 20 mm / min. The tearing force starting from the slit-shaped notch is 12 N or less.

A third aspect of the present invention is the optical drop cable according to the first or second aspect , wherein the optical fiber ribbon is disposed so that a major axis direction thereof is substantially orthogonal to a cable width direction. To do.

According to a fourth aspect of the present invention, in the optical drop cable according to any one of the first to third aspects, each of the slit-shaped notches is formed by cutting a jacket in a semi-molten state. It is characterized by being.

  According to the optical drop cable of the present invention, it is possible to drastically improve the core take-out property of the tape-shaped optical fiber core and to have extremely high damage resistance.

It is sectional drawing which shows the optical drop cable which concerns on one Embodiment of this invention. It is a schematic diagram which shows an example of the manufacturing apparatus used for manufacture of the optical drop cable which concerns on one Embodiment of this invention. It is a figure explaining the measuring method of the repulsive force of a slit-shaped notch. It is sectional drawing which shows the modification of the optical drop cable of this invention. It is sectional drawing which shows the other modification of the optical drop cable of this invention.

  Embodiments of the present invention will be described below. Although the description will be made based on the drawings, the drawings are provided for illustration only, and the present invention is not limited to the drawings. Moreover, in the following description, about the component which has the same or substantially the same function and structure, the same code | symbol is attached | subjected and the overlapping description is abbreviate | omitted.

  FIG. 1 is a cross-sectional view showing an embodiment of the optical drop cable of the present invention.

  As shown in FIG. 1, the optical drop cable 101 of this embodiment is a cable used for drawing and wiring from a wiring cable installed between utility poles to a subscriber's house such as a building or a general house. The optical drop cable 101 includes a cable portion 10, a support wire portion 20, and a connecting portion 30 that connects them.

  The cable portion 10 is arranged in parallel with a distance between the optical fiber tape core wire 11 and the optical fiber tape core wire 11 above and below the optical fiber tape core wire 11 so that their centers are located on substantially the same plane. Strength members 12 and 12 made of steel wire, FRP (fiber reinforced plastic), and the like, and a jacket 13 which is extrusion-coated collectively on the outside thereof. The optical fiber ribbon 11 is arranged so that the major axis direction thereof is substantially orthogonal to the cable width direction.

  The outer cover 13 is formed in a substantially rectangular cross section, and at the positions corresponding to the optical fiber ribbons on both sides thereof, the cross section is U-shaped, trapezoidal, or V-shaped in the longitudinal direction of the optical drop cable 101. (In the example of the drawing, a trapezoidal cross section) grooves 14 and 14 are formed, and slit-like notches 15 and 15 in a semi-fused state starting from the bottoms of the grooves 14 and 14 are optical fibers at the respective ends. It is provided so as to face each other across the tape core wire 11. Each tip of the slit-shaped notches 15, 15 reaches the vicinity of the optical fiber ribbon 11. These slit-shaped notches 15 and 15 in a semi-fused state are formed by cutting a slit (slit) on the surface when the outer cover 13 is in a semi-molten state and cooling and hardening it as it is. is there. In such slit-shaped notches 15 and 15, no slit is apparently observed, and the surface of the outer cover 13 has substantially the same appearance as the surface of the outer cover in which notches are not formed.

  Further, the outer jacket 13 is formed so as to be partially non-contacted with the outer jacket 13 only on the side surface parallel to the major axis direction of the outer peripheral surface of the optical fiber ribbon 11. In other words, gaps 16 and 16 are formed between the jacket 13 and the side surface parallel to the major axis direction of the optical fiber ribbon 11 so that the jacket 13 and the optical fiber ribbon 11 are not in close contact with each other. Is covered.

  Each gap portion 16 has a width (indicated by “a” in FIG. 1) that is not less than ¼ and not more than 3/4 of the long diameter of the optical fiber ribbon 11 (indicated by “b” in FIG. 1) (that is, the gap portion 16 It is preferable that the ratio (a / b) between the width a and the major axis b of the optical fiber ribbon 11 is not less than 1/4 and not more than 3/4. When the ratio (a / b) is less than ¼, the adhesion force of the optical fiber ribbon core 11 as a whole to the outer sheath 13 becomes excessive, and the extraction performance of the conductor decreases. On the other hand, if the ratio (a / b) exceeds 3/4, the close contact between the optical fiber tape core wire 11 and the jacket 13 becomes unstable in the longitudinal direction, microbends occur, and transmission characteristics and the like deteriorate. The ratio (a / b) is more preferably 1/2 or more and 3/4 or less. The shape of the gap portion 16 may be any shape as long as it does not deteriorate the characteristics required for the cable, such as mechanical characteristics and transmission characteristics. For example, it is rectangular as in the present embodiment. It may be oval or semicircular.

  On the other hand, the support wire portion 20 is composed of a support wire 21 made of a steel wire and the like, and a sheath 22 which is extrusion-coated integrally with the outer cover 13 of the cable portion 10 and the connecting portion 30 on the outer periphery thereof. The covering 22 has a circular cross section.

  The outer sheath 13 of the cable portion 10, the covering 22 of the support wire portion 20, and the connecting portion 30 are polyolefin resins having a Shore D hardness (hereinafter simply referred to as Shore D hardness) of 55 to 63 as measured in accordance with JIS K 7215. It is formed by batch extrusion. The type of polyolefin resin is not particularly limited as long as the Shore D hardness is within the above range. Specifically, polyethylene such as low density polyethylene (LDPE), medium density polyethylene (MDPE), high density polyethylene (HDPE), very low density polyethylene (VLDPE), and linear low density polyethylene (LLDPE), ethylene and propylene , 1-butene, 1-pentene, 1-hexene, 1-octene, ethylene-α-olefin copolymer obtained by copolymerizing α-olefin such as 4-methyl-1-pentene, ethylene-ethyl acrylate copolymer Polymer (EEA), ethylene / methyl acrylate copolymer (EMA), ethylene / ethyl methacrylate copolymer, ethylene / vinyl acetate copolymer (EVA), polypropylene (PP), polyisobutylene and the like are used. These are used alone or in combination. These resins may contain a flame retardant, a colorant, and the like. When the Shore D hardness of the polyolefin resin is less than 55, the effect of preventing damage caused by laying tubes such as Kumazemi is reduced, and when the Shore D hardness exceeds 63, the take-out property of the optical fiber is lowered. The Shore D hardness of the polyolefin resin is more preferably 55 or more and 61 or less.

  The optical fiber ribbon 11 is not particularly limited, and, for example, four optical fiber strands coated with an ultraviolet curable resin on the outer periphery of the optical fiber are juxtaposed, and further UV cured on the outer periphery. A type of resin that is covered with a mold resin is used.

  Further, as the material constituting the tensile body 12, in addition to steel wire and FRP, aramid fibers such as poly-p-phenylene terephthalamide fiber, polyester fibers such as polyethylene terephthalate fiber, nylon fibers, and these fibers are polyester- Examples include composite materials that are converged and bound with an acrylate resin.

Next, a method for manufacturing the optical drop cable 101 will be described.
FIG. 2 is a schematic diagram of an apparatus used for manufacturing the optical drop cable 101. As shown in FIG. 2, this manufacturing apparatus includes an optical fiber tape core wire delivery device 41 that sends out the optical fiber tape core wire 11, tensile strength body delivery devices 42 and 42 that send out the strength members 12 and 12, and a support wire 21. The support wire sending device 43 to send out, the preheating device 44 for preheating the sent optical fiber tape core wire 11, the preheated optical fiber tape core wire 11, the strength members 12, 12 and the support wire 21 are respectively predetermined. , An extruder 45 that coats the outer cover 13 and the resin for the coating 22, an auxiliary cooling water tank 46 that cools the resin to a semi-molten state, and a predetermined resin of the semi-molten resin. A slit processing device 47 for making a cut at a position, a main cooling water tank 48 for further cooling and hardening the resin, and a winding device 49 for winding the optical drop cable 101 Eteiru. The extruder 45 is equipped with a nipple having a recess formed at the tip so that the gap 16 as described above is formed when the outer jacket 13 and the coating 22 are covered.

  Tensile members 12, 12 sent from the optical fiber tape core wire 11, the tensile member feeding device 42, and the support wire sending device 43, respectively, sent from the optical fiber ribbon feeder 41 and preheated by the preheating device 44, and The support wire 21 is introduced into the extruder 45, and the heat-melted resin is extruded around the support wire 21 while being gathered at a predetermined position. By preheating the optical fiber core 11, it is possible to prevent bubbles from being generated at the interface between the optical fiber tape core 11 and the resin during resin coating. The bubbles are caused by a volatile component on the surface of the optical fiber ribbon 11, and when the bubbles are generated, minute voids are generated at the interface between the cooled optical fiber tape 11 and the resin. By performing preheating, the generation of such microvoids can be prevented.

  Each wire (the optical fiber tape core 11, the tensile body 12, and the support wire 21) coated with the resin in this way is an auxiliary cooling water tank 46. Specifically, until the resin is in a semi-molten state, specifically, the surface of the resin The resin is cooled to a temperature close to the melting point of the resin (in the case of the above-mentioned polyolefin resin, usually 100 to 150 ° C., preferably 100 to 130 ° C.) and then sent to the slit processing device 47 to be in a semi-molten state A slit is formed into a slit-shaped notch 15. The slit-shaped notch 15 in the semi-fused state cannot be formed even if the temperature at the time of making the slit notch 15 is too low or too high than the melting point of the resin. That is, if the temperature at the time of making the cut is too lower than the melting point of the resin, the cut surface of the cut will not be fused at all or will be insufficient, and a spawning tube such as a courge will be easily inserted. As a result, the protective effect against oviposition tubes such as bearfish is reduced. Conversely, if the temperature at the time of making the cut is too higher than the melting point of the resin, the cut surface of the cut will be fused, and the slit-shaped notch 15 will not function as a notch. That is, it becomes impossible to tear the slit-shaped notch 15 as a starting point. As a result, the take-out property of the core wire becomes poor.

  After the slit-shaped notch 15 is formed on the resin surface in this way, the resin is further cooled and cured in the main cooling water tank 48, and the optical drop cable 101 is obtained. The obtained optical drop cable 101 is wound around the winding device 49.

  In the optical drop cable 101 of the present embodiment, the tearing notch is not apparently formed, so that the egg-laying tube such as a bear swallow is not guided to the optical fiber core wire 11 as in the prior art. In addition, even if an oviposition tube such as a burdock is pierced into the outer cover 13, the outer cover 13 has a Shore D hardness (JIS K 7215) of 55 to 63, which is a harder material than the conventional outer cover material. Therefore, the tip does not pierce deeply into the outer jacket 13. Therefore, it is possible to prevent the optical fiber from being broken by the egg-laying tube such as the bearfish.

On the other hand, when the optical fiber ribbon 11 is taken out, the slit-shaped notch 15 has a cut surface that is not completely fused and is in a semi-fused state, and can be easily separated by hand. If the cable portion 10 is torn in the width direction starting from the separated slit-shaped notch 15, the outer sheath 13 and the optical fiber tape core wire 11 are not brought into close contact with each other by the formation of the gap portion 16 at the tip of the tearing direction. Further, since the optical fiber ribbon 11 is present, the optical fiber ribbon 11 can be easily taken out.

  In addition, from the viewpoint of protecting the optical fiber ribbon 11 from the kazemi and the like, and improving the take-out property of the optical fiber ribbon 11, the tearing force starting from the slit-shaped notch 15 may be 15 N or less. Also, as shown in FIG. 3, the repulsive force (measured by the load cell 52) when the surface of the slit-shaped notch 15 is pressed by 0.5 mm with a needle 51 having a diameter of 1.0 mm is preferably 3N or more. . The tearing force is more preferably 10N or less, and the repulsion force is more preferably 3.5N or more.

  Moreover, from the viewpoint of further improving the take-out property of the optical fiber ribbon 11, the adhesion force with respect to the jacket 13 as the entire optical fiber ribbon 11 is preferably 10 N or more and 78 N or less, and 10 N or more and 60 N or less. It is more preferable that

  Here, it describes about the experiment conducted in order to investigate the effect of this invention, and its result.

  An optical drop cable having the structure shown in FIG. 1 was manufactured using the manufacturing apparatus shown in FIG.

  That is, one optical fiber ribbon 11, two tensile members 12 and one support wire 21 are introduced into the extruder 45 in a state of being arranged in parallel as shown in FIG. A polyolefin resin having a Shore D hardness of 55 or more and 63 or less shown below is batch-extruded and coated, and then passed through an auxiliary cooling water tank 46, a slit processing device 47, and a main cooling water tank 48 in order, and the overall width is about 2 0.0 mm, the same height is about 5.9 mm, has a slit-shaped notch 15 with a depth (full length) of about 0.4 mm, and is compared with the side surface in the major axis direction of the optical fiber ribbon 11 (a / b) The optical drop cable shown in FIG. 1 provided with the gap 16 having a rectangular cross section such that is 1/6, 1/4, 1/2, 3/4, or 1 was manufactured. In the optical fiber ribbon 11, a four-fiber optical fiber tape having a major axis of 1.1 mm and a minor axis of 0.3 mm, in which four optical fiber strands are arranged in parallel and the outer periphery thereof is collectively coated with an ultraviolet curable resin. A core wire was used, an aramid FRP having an outer diameter of 0.5 mm was used for the strength member 12 of the cable portion 10, and a galvanized steel wire having an outer diameter of 1.2 mm was used for the support wire 21. In addition, the preheating temperature of the optical fiber ribbon 11 was 200 ° C., and the surface temperature of the resin (slit processing temperature) when passing through the slit processing device 47 was 120 ° C.

  For comparison, the above optical drop cable except that a polyolefin resin having a Shore D hardness of less than 55 or more than 63 shown below was used instead of the polyolefin resin having a Shore D hardness of 55 or more and 63 or less. In the same manner, an optical drop cable was manufactured.

  Further, an optical drop cable was manufactured in the same manner as each of the optical drop cables described above except that the gap portion 16 was not formed and the outer peripheral surface of the optical fiber ribbon 11 was all in close contact with the jacket 13.

[Coating materials]
Polyolefin resin A: Shore D hardness 50
Polyolefin resin B: Shore D hardness 56
Polyolefin resin C: Shore D hardness 60
Polyolefin resin E: Shore D hardness 61
Polyolefin resin E: Shore D hardness 62
Polyolefin resin F: Shore D hardness 67

  About each said optical drop cable, when the adhesive force with respect to the jacket as the whole optical fiber ribbon, the tearing force starting from the slit-shaped notch, and the slit-shaped notch surface is pressed 0.5 mm with a needle having a diameter of 1.0 mm In addition to measuring the repulsive force, the transmission characteristics, the core wire take-out property, and the effect of preventing the invasion of the burrowing oviduct into the laying tube were evaluated by the following methods. The evaluation results are shown in Table 1 and Table 2 together with the type of the jacket material and its physical properties.

[Adhesion]
The optical fiber ribbon was exposed from the jacket leaving a length of 10 mm, one end was pulled at a pulling speed of 20 mm / min, and the force required for pulling out was measured.
[Tearing force]
A cable sample cut to a length of 20 cm was measured under the conditions of a tearing speed of 100 mm / min, an initial fixing distance of 30 mm, and a tearing length of 100 mm.
[Transmission characteristics]
Using OTDR, optical loss was measured at a wavelength of 1.55 μm, and 0.30 dB / km or less was accepted.
[Core extractability]
With respect to the cable sample cut out to a length of 50 cm, the take-out property of the optical fiber ribbon when the jacket was torn by hand using a notch was evaluated according to the following criteria.
◎: Extremely easy to remove ○: Easy to remove △: Difficult to remove (practically hindered)
×: Unable to take out (fiber optic tape core breaks [damage resistance]
An optical drop cable was laid out outdoors for 30 days during the period when the bearfish appeared, and the number of samples (n = 5) in which the optical fiber was disconnected due to the invasion of the eggplant of the bearfish was examined.

  As shown in Table 1 and Table 2, the optical fiber cable of the present invention can dramatically improve the core wire take-out property of the optical fiber ribbon and has extremely high damage resistance. .

  In addition, this invention is not limited to description content of embodiment described above, It cannot be overemphasized that it can implement with a various aspect in the range which does not deviate from the summary of this invention.

  For example, as shown in FIG. 4, in the above embodiment, the number of the optical fiber ribbons 11 accommodated in the cable portion 10 may be two or more. In the embodiment shown in FIG. 1, the optical drop cable 102 shown in FIG. 4 is obtained by arranging two optical fiber ribbons 11 so as to overlap each other in the minor axis direction.

  Although not shown, it is possible to have a structure without the support wire portion 20, and a plurality of cable portions 10 having a larger diameter than that of the optical drop cable 101 shown in FIG. It is good also as a structure twisted around 20 around, without integrating with a support wire part. The latter optical drop cable is used as a so-called aerial collective optical drop cable constructed between utility poles immediately before an optical fiber is drawn into a subscriber's house using an optical drop cable as shown in FIG.

  Further, in all of the examples described above, the slit-shaped notch 15 is provided so that a straight line whose tip extends in the cable width direction passes through the substantial center of the optical fiber ribbon 11. For example, FIG. 1, one of the slit-shaped notches 15 may be positioned above the position of the optical fiber tape core wire 11 and the other may be positioned below the position of the optical fiber tape core wire 11. Only one of the notches 15 may be positioned above or below the position of the optical fiber ribbon 11. Furthermore, in this case, as long as the leading ends of both slit-shaped notches 15 reach the vicinity of the optical fiber ribbon 11, it is not always necessary to oppose the optical fiber ribbon 11. In the embodiment shown in FIG. 1, the optical drop cable 103 shown in FIG. 5 has one of the slit-shaped notches 15 above the position of the optical fiber ribbon 11 and the other of the optical fiber tape core 11. In addition to being positioned further downward, the leading ends of both slit-shaped notches 15 are opposed to each other with the optical fiber ribbon 11 interposed therebetween.

  In these optical drop cables as well as the optical drop cable 101 described with reference to FIG. 1, it is possible to prevent the optical fiber from being broken by the laying tube such as a bear swallow, and the slit-shaped notches 15 and the gaps 16 are formed. By forming, the optical fiber ribbon 11 can be taken out very easily.

  DESCRIPTION OF SYMBOLS 10 ... Cable part, 11 ... Optical fiber tape core wire, 12 ... Strength member, 13 ... Outer jacket, 14 ... Groove, 15 ... Slit-like notch in a semi-fusion state, 16 ... Gap part, 20 ... Support line part, 21 DESCRIPTION OF SYMBOLS ... Support line, 22 ... Coating | cover, 45 ... Extruder, 46 ... Auxiliary cooling water tank, 47 ... Slit processing apparatus, 48 ... Main cooling water tank, 101-103 ... Optical drop cable.

Claims (4)

An optical drop cable comprising an optical fiber ribbon, tensile strength members arranged in parallel on both sides of the optical fiber ribbon, and a jacket covering them all at once,
The jacket is formed of a polyolefin resin having a Shore D hardness (JIS K 7215) of 56 or more and 62 or less, and the jacket is only on a surface in contact with a side surface parallel to the major axis direction of the optical fiber ribbon. Provided with a gap that non-contacts the jacket and the optical fiber ribbon, and provided a slit-like notch in a semi-fused state in which a pair of tips reach the vicinity of the gap on the jacket surface,
The ratio a / b between the width a in the major axis direction of the optical fiber ribbon and the major axis b of the optical fiber ribbon is not less than 1/2 and not more than 3/4, and the optical fiber Adhesion force of the tape core wire to the outer sheath (here, the adhesion force is obtained by pulling one end of the optical fiber ribbon exposed from the outer sheath with a length of 10 mm at a pulling speed of 20 mm / min. The optical drop cable has a tearing force starting from each slit-like notch of 12 N or less. A cable part comprising an optical fiber ribbon, tensile strength members arranged in parallel at intervals on both sides of the optical fiber ribbon, and a jacket covering them all together, and a support for supporting the cable part An optical drop cable having a support wire portion with a wire,
The jacket is formed of a polyolefin resin having a Shore D hardness (JIS K 7215) of 56 or more and 62 or less, and the jacket is only on a surface in contact with a side surface parallel to the major axis direction of the optical fiber ribbon. Provided with a gap that non-contacts the jacket and the optical fiber ribbon, and provided a slit-like notch in a semi-fused state in which a pair of tips reach the vicinity of the gap on the jacket surface,
The ratio a / b between the width a in the major axis direction of the optical fiber ribbon and the major axis b of the optical fiber ribbon is not less than 1/2 and not more than 3/4, and the optical fiber Adhesion force of the tape core wire to the outer sheath (here, the adhesion force is obtained by pulling one end of the optical fiber ribbon exposed from the outer sheath with a length of 10 mm at a pulling speed of 20 mm / min. The optical drop cable has a tearing force starting from each slit-like notch of 12 N or less.   The optical drop cable according to claim 1 or 2, wherein the optical fiber ribbon is disposed such that a major axis direction thereof is substantially orthogonal to a cable width direction.   4. The optical drop cable according to claim 1, wherein each of the slit-shaped notches is a notch formed by cutting a jacket in a semi-molten state. 5.

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