JP7207215B2 - fiber optic cable - Google Patents

Description

TECHNICAL FIELD The present disclosure relates to optical fiber cables with multiple optical fiber cores.

Patent Literature 1 describes a pneumatic cable for laying an optical fiber cable, in which a plurality of optical fiber core wires are collectively coated, in a duct (duct) by pneumatically feeding compressed air.
Patent Literatures 2 and 3 describe an optical fiber cable having identification markings on the surface of the cable jacket.

JP-A-3-128616 JP 2012-032683 A JP 2013-020097 A

For example, a pneumatic cable, such as that described in US Pat. However, there is a risk that friction will occur between the surface of the cable jacket and the inner surface of the duct during air feeding, shortening the pumping distance.
Further, the optical fiber cable may have an identification mark (marking) on the surface of the cable jacket, as disclosed in Patent Documents 2 and 3, for example. Various cases are possible for the content of the identification display, but information such as the number of optical fibers, product name, company name, manufacturing year, length (position), etc. is often included.
However, if an optical fiber cable such as a pneumatic cable has an identification mark on the surface of the cable jacket, the identification mark is scraped off by rubbing the surface of the cable jacket and the inner surface of the duct during air feeding. It may become difficult to see.

SUMMARY OF THE INVENTION An object of the present disclosure is to provide an optical fiber cable that can extend the pumping distance when pneumatically fed in a duct and that makes it easy to visually recognize an identification mark provided on the cable jacket.

A fiber optic cable according to one aspect of the present disclosure includes:
a plurality of optical fiber core wires;
a cable sheath enclosing the plurality of optical fiber core wires;
has
the cable jacket has a plurality of recesses and protrusions,
Only the concave portion is marked for identification,
The recess has a width of 3 mm or more in the circumferential direction of the cable jacket,
The ratio between the width of the recess and the width of the protrusion in the circumferential direction of the cable jacket is less than 2:1.

Advantageous Effects of Invention According to the present disclosure, it is possible to provide an optical fiber cable that can extend the pumping distance when air is fed in a duct, and that makes it easy to visually recognize the identification mark provided on the cable jacket.

1 is a perspective view showing the configuration of an optical fiber cable according to an embodiment; FIG. It is a schematic diagram which shows a cable pumping evaluation apparatus.

(Description of Embodiments of the Present Disclosure)
First, the embodiments of the present disclosure are listed and described.
An optical fiber unit according to one aspect of the present disclosure includes:
(1) a plurality of optical fiber core wires;
a cable sheath enclosing the plurality of optical fiber core wires;
has
the cable jacket has a plurality of recesses and protrusions,
Only the concave portion is marked for identification,
The recess has a width of 3 mm or more in the circumferential direction of the cable jacket,
The ratio between the width of the recess and the width of the protrusion in the circumferential direction of the cable jacket is less than 2:1.
According to the optical fiber cable having the above configuration, there is little possibility that the concave portion and the inner surface of the duct will rub against each other when the air is fed, so there is little possibility that the identification mark applied only to the concave portion will be scraped off. Therefore, it is easy to visually recognize the identification mark provided on the cable jacket. In addition, since the surface of the cable jacket is provided with concave portions, the surface becomes uneven, so that the contact area with the inner surface of the duct is reduced, and the friction between the surface of the cable jacket and the inner surface of the duct can be reduced when air is fed. This makes it possible to extend the pumping distance when air is pumped in the duct.

(2) The identification mark may be an identification mark formed by an inkjet printer or a laser printer.
According to the optical fiber cable configured as described above, numbers and letters for identification are printed by an ink-jet printer or a laser printer, which generally has a high printing speed. As a result, the time required for the process of forming the identification mark can be shortened, so that the manufacturing speed of the optical fiber cable can be increased.

According to the optical fiber cable having the above configuration, since the width of the concave portion on the surface of the cable jacket is 3 mm or more, it is possible to provide an identification display of letters or numbers of 2 mm or more that are generally easily visible to the naked eye. However, if the width of the recess is widened, the recess contacts the inner surface of the duct, increasing the friction between the surface of the cable jacket and the inner surface of the duct, and there is a risk that the identification mark provided on the recess may be scraped off. In the optical fiber cable having the above configuration, the ratio of the width of the concave portion to the width of the convex portion is smaller than 2:1, so the contact of the concave portion with the inner surface of the duct can be suppressed.

(Details of embodiments of the present disclosure)
A specific example of an optical fiber cable according to an embodiment of the present disclosure will be described below with reference to the drawings.
The present invention is not limited to these exemplifications, but is indicated by the scope of the claims, and is intended to include all modifications within the scope and meaning equivalent to the scope of the claims.

FIG. 1 is a perspective view showing the configuration of an optical fiber cable 1 according to an embodiment. As shown in FIG. 1, an optical fiber cable 1 includes a plurality of optical fiber ribbons 2, a water absorbing tape 3 surrounding the optical fiber ribbons 2, and a cable jacket 4 surrounding the water absorbing tape 3. , a tensile member 5 and a tear cord 6 provided inside the cable jacket 4 .

The optical fiber tape core wires 2 are accommodated in the optical fiber cable 1 in a state of being rolled and collected, for example. Alternatively, a plurality of optical fiber tape core wires 2 may be twisted together to form a unit, and the plurality of units may be housed in an aggregated state. In order to mount the optical fiber ribbons 2 in the optical fiber cable 1 with high density, the optical fiber ribbons 2 are preferably, for example, intermittently connected optical fiber ribbons. The bundled optical fiber ribbons 2 may be bundled with a bundle material or the like, or may be bundled with a bundle material for each unit. Further, in this example, the optical fiber tape core wire 2 is accommodated in the optical fiber cable 1, but the optical fiber core wire may be accommodated as it is without being tape-shaped.

The water absorbing tape 3 is wound around the entirety of the plurality of optical fiber ribbons 2, for example, vertically or horizontally. The water-absorbing tape 3 is, for example, a base fabric made of polyester or the like which has undergone water-absorbing processing by adhering water-absorbing powder thereto.

The cable jacket 4 is made of resin such as polyethylene (PE), for example. The resin of the cable jacket 4 preferably has a Young's modulus of 500 Pa or more. The cable jacket 4 contains, for example, a silicon-based lubricant. The silicon-based lubricant is preferably contained, for example, at a rate of 2 wt % or more. The cable jacket 4 is made of thermoplastic resin, for example, and is formed by extruding the resin onto the plurality of optical fiber tape core wires 2 around which the water absorbing tape 3 is wound.

The tensile strength member 5 is provided so as to be embedded inside the cable jacket 4 . The tensile member 5 is made of, for example, fiber reinforced plastic (FRP), such as aramid FRP, glass FRP, or carbon FRP. The tensile strength member 5 is circular in cross section. A plurality of (four in this example) tensile members 5 are provided. Each of the four tensile members 5 is provided with two pairs of two tensile members 5 that are opposed to each other across the center of the optical fiber cable 1 in a cross-sectional view of the optical fiber cable 1 . The positions of the four tensile strength members 5 in a cross-sectional view are positions at which the two straight lines connecting the two paired tensile members 5 intersect each other. Each strength member 5 is provided within the cable jacket 4 along the longitudinal direction of the optical fiber cable 1 .

The tear string 6 is a string for tearing the cable jacket 4 and is embedded in the cable jacket 4 along the longitudinal direction of the optical fiber cable 1 . In the case of this example, two tearing strings 6 are provided. The two tearing strings 6 are provided at approximately the middle position between the adjacent tensile strength members 5 so as to face each other. By pulling out the tear string 6, the cable jacket 4 is torn in the longitudinal direction, and the optical fiber ribbon 2 can be taken out. The tear string 6 is made of, for example, a plastic material (eg, polyester) that is resistant to tension.

Next, the structure of the cable jacket 4 will be described in detail.
The cable jacket 4 has a recess 7 on its surface. A convex portion 8 is provided on the surface of the cable jacket 4 other than the concave portion 7 . The concave portions 7 and the convex portions 8 are alternately provided on the surface of the cable jacket 4 so as to be adjacent to each other when the optical fiber cable 1 is viewed in cross section. In this example, four recesses 7 and four protrusions 8 are provided in a cross-sectional view. The four recesses 7 and the four projections 8 are provided on the surface of the cable jacket 4 at substantially equal intervals in a cross-sectional view. Note that the number of recesses 7 and protrusions 8 is not limited to four.

The concave portion 7 is a portion in which the diameter of the optical fiber cable 1 is smaller than that of the convex portion 8 in a cross-sectional view of the cable jacket 4 . The concave portion 7 is continuously provided linearly along the longitudinal direction of the optical fiber cable 1 . Although the convex portion 8 is also provided along the longitudinal direction of the optical fiber cable 1, the convex portion 8 may be provided continuously along the longitudinal direction, or may be intermittently provided. .
Further, the concave portion 7 and the convex portion 8 may be provided linearly along the longitudinal direction of the optical fiber cable 1, or may be provided spirally. The concave portion 7 and the convex portion 8 of this example are continuously provided linearly along the longitudinal direction of the optical fiber cable 1 . The concave portion 7 and the convex portion 8 are integrally formed by, for example, extrusion molding. In addition, in the example of FIG. 1, the end surface 8a of the protrusion 8 in the direction in which the protrusion 8 protrudes is formed of a curved surface with a constant curvature, but the present invention is not limited to this. For example, it may be a combination of curved surfaces with different curvatures or flat surfaces. Also, the surface of the recess 7 may not be an arc-shaped curved surface, and may be, for example, a combination of curved surfaces with different curvatures or flat surfaces.

The ratio of the width Wc of the concave portion 7 in the circumferential direction of the cable jacket 4 to the width Wv of the convex portion 8 in the circumferential direction of the cable jacket 4 is set to be smaller than 2:1. That is, the width Wc of the concave portion 7 and the width Wv of the convex portion 8 are formed so as to satisfy the relationship of Wc<2Wv.
Further, the width Wc of the concave portion 7 is formed to be 3 mm or more. Width Wc may vary, for example, depending on the outer diameter of optical fiber cable 1 .

Further, on the surface of the cable jacket 4, an identification mark (marking) 9 for identifying the optical fiber cable 1 is applied. The identification mark 9 is applied only to the recess 7 of the cable jacket 4 . The identification display 9 includes information such as product name, company name, the number of optical fibers contained in the optical fiber cable 1, the length (position) of the cable, and the year of manufacture. The size of characters, numbers, etc. included in the identification display 9 is, for example, 2 mm or more in the vertical direction. The size of the identification mark 9 can be changed according to the size of the width Wc of the recess 7 . The identification mark 9 is printed by spraying ink on the concave portion 7 using an inkjet printer, for example. Alternatively, the identification indicia 9 are printed by transferring toner to the recesses 7 using a laser printer.

Further, the identification display 9 may be formed by, for example, a hot stamping method in which a stamp is pressed against the concave portion 7 to engrave characters, numbers, or the like.
Further, the identification mark 9 may be, for example, a colored belt extending along the longitudinal direction of the cable on the surface of the recess 7 . Also, the color bands may be provided together with the letters, numbers, and the like. The color band is formed, for example, by simultaneously extruding a material having a different color from that of the jacket main body portion through a die when the cable jacket 4 is extruded.

In the optical fiber cable 1 described above, the outer diameter of the optical fiber cable 1 is, for example, 16 mm or less when the inner diameter of the microduct for pneumatically feeding the optical fiber cable 1 is 20 mm or less. Further, for example, when the inner diameter of the microduct for pneumatically feeding the optical fiber cable 1 is 14 mm or less, the outer diameter of the optical fiber cable 1 is 11 mm or less.

Further, the core density obtained by dividing the number of cores of all the optical fibers constituting the plurality of optical fiber tape core wires 2 by the cable cross-sectional area of the optical fiber cable 1 is preferably 5.0 cores/mm ² or more. . For example, when the outer diameter of the optical fiber cable 1 is 10 mm, the thickness of the cable jacket 4 is 1.0 mm, and the outer diameter of the optical fiber core wire is 200 μm, the cable jacket 4 of the optical fiber cable 1 contains If the number of accommodated 12 optical fiber tape core wires 2 is 36, the total number of optical fiber core wires at that time is 432 cores, and the core density is 5.5 cores/mm ² . . Moreover, the radial bending rigidity of the optical fiber cable 1 is preferably 0.35 N·m ² or more and 1.3 N·m ² or less in the circumferential direction. Further, when the tensile strength member 5 is formed of four aramid FRPs, for example, when the outer diameter of the optical fiber cable 1 is 10 mm and the thickness of the cable jacket 4 is 1.0 mm, the outer diameter of the aramid FRP The diameter is preferably 0.5 mm or more.

As described above, the optical fiber cable 1 according to the present embodiment includes a plurality of optical fiber tape core wires 2, and a cable jacket 4 that encloses these optical fiber tape core wires 2 and has recesses 7 on its surface. , is equipped with Only the concave portion 7 is provided with an identification mark 9. As shown in FIG. According to this configuration, when the optical fiber cable 1 is pneumatically fed, the recess 7 is less likely to come into contact with the inner surface of the duct, so the identification mark 9 applied to the recess 7 is less likely to be scraped off by rubbing against the inner surface of the duct. Therefore, the visibility of the identification mark 9 provided on the cable jacket 4 can be maintained at a high level. In addition, since the surface of the cable jacket 4 is provided with the recesses 7, the surface has an uneven structure, so the contact area between the optical fiber cable 1 and the inner surface of the duct is reduced, and the surface of the cable jacket 4 and the inner surface of the duct when air is fed. can reduce friction with As a result, the pumping distance can be extended when the optical fiber cable 1 is pneumatically fed within the duct. In addition, since the identification mark 9 is applied only to the concave portion 7 on the surface of the cable jacket 4, the identification mark 9 does not overlap the boundary between the concave portion 7 and the convex portion 8, and is included in the identification mark 9. Visibility of numbers, characters, etc. can be improved.

The optical fiber cable 1 is printed with numbers, letters, etc. for the identification display 9 by an ink-jet printer or a laser printer, which generally has a high printing speed. Therefore, the time required for the process of forming the identification mark 9 can be shortened, so that the manufacturing efficiency of the optical fiber cable 1 can be improved.

Further, the optical fiber cable 1 is formed so that the width Wc of the concave portion 7 on the surface of the cable jacket 4 is 3 mm or more. For this reason, it is possible to provide an identification display 9 of characters or numbers of 2 mm or more, which is generally considered to be easily visible with the naked eye, in the concave portion 7 of the cable jacket 4 . Therefore, the visibility of the identification display 9 on the optical fiber cable 1 can be improved.

However, if the width Wc of the recess 7 is made too wide, the recess 7 may come into contact with the inner surface of the duct and the identification mark 9 applied to the recess 7 may be scraped off. Further, when the concave portion 7 contacts the inner surface of the duct, the friction between the surface of the cable jacket 4 and the inner surface of the duct increases. On the other hand, according to the optical fiber cable 1, the ratio of the width Wc of the concave portion 7 to the width Wv of the convex portion 8 is smaller than 2:1. Thereby, it is possible to prevent the concave portion 7 from coming into contact with the inner surface of the duct, and it is possible to prevent the identification mark 9 from being scraped off. Further, since the convex part 8 can be brought into contact with the inner surface of the duct, it is possible to suppress an increase in friction between the surface of the cable jacket 4 and the inner surface of the duct, and a sufficiently long pumping distance can be secured.

(Example)
In the optical fiber cable according to this embodiment, the visibility of the identification mark and the pumping distance were evaluated for a plurality of samples having different ratios of the width of the concave portion to the width of the convex portion. Table 1 shows the evaluation results.

In Table 1, the outer diameter of the optical fiber cable is 10 mm. The number of concave portions (convex portions) of the cable jacket is four, which is the same as the number of concave portions (convex portions) of the optical fiber cable 1 shown in FIG. Cable jacket identification indicia were printed with 2 mm letters and numbers in recesses using an inkjet printer.

The visibility of the identification display is whether the printed letters and numbers are visible and distinguishable from other letters and numbers (for example, whether the printed numbers are "8" or "0"). ) was determined visually.
For the pumping distance, a microduct pumping test conforming to IEC was performed using the pumping apparatus shown in FIG. The pipe 20 has a length of 1000m and is folded back every 100m. The bend (R) of the pipe 20 is 40 times the outer diameter of the pipe, and the inner diameter of the pipe 20 is 14 mm. Aperture 21 is the inlet for air and fiber optic cable, and aperture 22 is the outlet for air and fiber optic cable. The air pressure was 1.3 MPa to 1.5 MPa.

The evaluation of the visibility of the identification display was as follows: evaluation A for good visual recognition, evaluation B for visual recognition, and evaluation C for difficult visual identification.
The pumping distance was evaluated as A when the pumping distance was 1000 m or more, B when the pumping distance was 600 m or more and less than 1000 m, and C when the pumping distance was less than 600 m.

According to the evaluation results in Table 1, in terms of the visibility of the identification display, the sample with good visibility (sample of evaluation A) was No. It was 2-7. Also, the visually recognizable sample (evaluation B sample) was No. was 1. As a result, it was found that when the width of the concave portion was 3 mm or more, the visibility of the identification mark was good. On the other hand, if the width of the concave portion is 2.5 mm, it is possible to print 2 mm characters or the like in the concave portion, but due to manufacturing variations, the identification mark may overlap the boundary between the concave portion and the convex portion. In this case, it was found that although it is possible to visually recognize, it cannot be said that the visibility is good.

In addition, samples with a pumping distance of 1000 m or more (samples of evaluation A) were No. It was 1-6. Samples with a pumping distance of 600 m or more and less than 1000 m (evaluation B samples) are No. was 7. It was found that for fiber optic cables, the pumping distance is good when the ratio of the width of the recess to the width of the protrusion is less than 2:1.

Although the present invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention. Further, the number, positions, shapes, etc. of the constituent members described above are not limited to those in the above-described embodiment, and can be changed to suitable numbers, positions, shapes, etc. in carrying out the present invention.

1: optical fiber cable 2: optical fiber tape core wire 3: water absorbing tape 4: cable jacket 5: tensile strength member 6: tear string 7: concave portion 8: convex portion 8a: end surface 9: identification mark 20: pipe 21, 22 : Aperture Wc: Width of concave portion Wv: Width of convex portion

Claims (2)

a plurality of optical fiber core wires;
a cable sheath enclosing the plurality of optical fiber core wires;
has
the cable jacket has a plurality of recesses and protrusions,
Only the concave portion is marked for identification,
The recess has a width of 3 mm or more in the circumferential direction of the cable jacket,
wherein the ratio of the width of the recess to the circumferential width of the cable jacket of the protrusion is less than 2:1;
fiber optic cable. wherein the identification mark is an identification mark formed by an inkjet printer or a laser printer;
The optical fiber cable of Claim 1.

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