JP2010039020A - Slot type optical cable - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To maintain loss characteristics in a low temperature environment while reducing a diameter of a slot type optical cable. <P>SOLUTION: The slot type optical cable 1 includes a slot rod 10 having a storage groove 12 in its outer peripheral part and tape core wires 20 constituted by arranging a plurality of optical fibers 21 in one row and covering them all together and storing them in the storage groove 12 while the number of n tape core wires or more (n is integer of 3 or more) are stacked in the radial direction of the slot rod 10. The thickness δ1 of the tape core wire 20 arranged on the outermost side in the radial direction of the slot rod 10 and the thickness δn of the tape core wire 20 arranged on the innermost side in the radial direction of the slot rod 10 are set to be larger than the thickness δi of the other tape core wires 20. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a slot type optical cable.

  The slot type optical cable includes a slot rod provided with a plurality of storage grooves for storing optical fibers, a presser winding wound around the outer periphery of the slot rod in which the optical fiber is stored, a sheath for storing the presser winding, and the like. . An optical fiber is accommodated, for example, as a tape core formed by integrating a plurality of optical fibers with a resin into a tape shape (see, for example, Patent Document 1).

  A plurality of helical storage grooves are formed along the longitudinal direction on the outer periphery of the slot rod. As the shape of the storage groove, 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 with a predetermined length.

A plurality of tape cores are stacked and stored in the storage groove of the slot rod, and the depth of the storage groove is larger than the total thickness of the stacked tape cores, and a clearance is secured. The slot rod is made of resin such as hard polyethylene, which has a higher expansion / contraction ratio due to temperature change than the tape core, so it shrinks in a low temperature environment, and the length of the tape core is relatively large, but the clearance is sufficiently large In this case, even in a low temperature environment, the extra length of the tape core wire gently bends inside the storage groove, so that an increase in loss can be prevented.
JP-A-8-262294

  By the way, in recent years, since there is a high demand for reducing the diameter of the cable, it is required to reduce the depth of the storage groove. However, if the depth of the storage groove is reduced, the tape core wire having a relatively long length in a low temperature environment cannot be gently bent in the storage groove, and the transmission loss of the optical fiber increases. is there.

  On the other hand, if the clearance is ensured by reducing the thickness of the tape core, the rigidity of the tape core cannot be ensured, and the transmission loss of the optical fiber may increase.

  An object of the present invention is to maintain loss characteristics in a low-temperature environment while reducing the diameter of a slot-type optical cable.

  In order to solve the above problems, the invention according to claim 1 is a slot-type optical cable, in which a slot rod having a housing groove formed in the outer peripheral portion and a plurality of optical fibers are arranged in a row and covered collectively. And a tape core wire accommodated in the housing groove in a state where n or more (n is an integer of 3 or more) are laminated in the radial direction of the slot rod, and the outermost radial direction of the slot rod The thickness of the tape core wire disposed on the inner side of the slot rod and the thickness of the tape core wire disposed on the innermost side in the radial direction of the slot rod are thicker than the thicknesses of the other tape core wires.

A second aspect of the present invention is the slot type optical cable according to the first aspect, wherein the optical fiber has a diameter of 0.24 to 0.26 mm, and is disposed on the outermost side in the radial direction of the slot rod. The thickness δ1 of the tape core wire, the thickness δn of the tape core wire disposed on the innermost side in the radial direction of the slot rod, and the i th sheet from the outer side in the radial direction of the slot rod (i is 2 to n− The thickness δi of the tape core wire having an integer of 1 has the following relationship.
0.29mm ≦ δ1 ≦ 0.33mm
0.29mm ≦ δn ≦ 0.33mm
0.27 mm ≦ δi ≦ 0.29 mm
δ1-δi ≧ 0.02mm
δn−δi ≧ 0.02 mm

  The invention according to claim 3 is the slot type optical cable according to claim 2, wherein n ≧ 10.

Invention of Claim 4 is the slot type optical cable of Claim 2 or 3, Comprising: The difference C of the depth of the said storage groove and the lamination | stacking height of the said tape core wire is 0 <= C <= 0.7mm
It is characterized by being.

The invention according to claim 5 is the slot type optical cable according to any one of claims 2 to 4, wherein the space factor β is 0.65 ≦ β ≦ 1.
It is characterized by being.
Here, the space factor is the total cross-sectional area of the laminated tape cores / the cross-sectional area of the storage groove.

  According to the present invention, it is possible to maintain loss characteristics in a low temperature environment while reducing the diameter of the slot type optical cable.

Hereinafter, the present invention will be described in detail.
FIG. 1 is a sectional view showing a slot type optical cable 1 according to an embodiment of the present invention. The slot-type optical cable 1 is generally composed of a slot rod 10, a tape core wire 20, a presser winding 30, a sheath 40, and the like.

  The slot rod 10 is made of, for example, a resin such as hard polyethylene, and a tension member 11 that bears the tension is provided in the center of the slot rod 10 in the axial direction. The tension member 11 is a steel wire, for example, and seven steel wires are used in FIG.

In addition, a plurality of storage grooves 12 extending in the longitudinal direction at intervals in the circumferential direction of the slot rod 10 are provided on the outer periphery of the slot rod 10. In FIG. 1, 13 storage grooves 12 are provided. It has been. A plurality of laminated tape core wires 20 are accommodated in the storage grooves 12, respectively.
In a state where the tape core wire 20 is housed in the housing groove 12, the presser winding 30 is wound around the outer periphery of the slot rod 10, and the sheath 40 is provided on the outer periphery of the presser winding 30.

FIG. 2 is an enlarged cross-sectional view showing the tape core wire 20 housed in the housing groove 12. As shown in FIG. 2, the tape core wire 20 is formed in a tape shape by arranging a plurality of optical fibers 21 in a row and collectively covering with a covering material 22.
As the covering material 22, for example, a UV curable resin or the like can be used.
In FIG. 2, eight optical fibers 21 are arranged in a row and are collectively covered with a covering material 22.

The plurality of tape core wires 20 are housed in the housing grooves 12 in a state where they are stacked in the radial direction of the slot rod 10. In FIG. 2, ten tape core wires 20 are laminated.
The storage groove 12 has a flat shape at the bottom in FIGS. 1 and 2, but the present invention is not limited to this. For example, as shown in FIG. 3, the storage groove 12 has a substantially U-shaped storage groove 12 having an R shape at the bottom. Can also be applied.

Here, each parameter described in FIGS. 2 and 3 will be described. h is the depth of the storage groove 12, δ1 is the thickness of the tape core wire 20 arranged on the outermost side in the radial direction of the slot rod 10, and δn is arranged on the innermost side in the radial direction of the slot rod 10. Δi is the thickness of the i-th tape core wire 20 (i is an integer of 2 to n−1) from the outside in the radial direction of the slot rod 10. Further, δs is the sum of the thicknesses of all the laminated tape cores 20, and C is a clearance (= h−δs).
The total sectional area of the laminated tape core wires 20 / the sectional area of the storage groove 12 is defined as a space factor β (β ≦ 1).

  In order to reduce the diameter of the slot type optical cable 1, it is necessary to reduce the diameter of the slot rod 10.

  In order to reduce the diameter of the slot rod 10, the clearance C is preferably as small as possible, 0.7 mm or less, and the space factor β is preferably 0.65 or more. However, when the clearance C (= h−δs) is not sufficiently large, the tape core wire 20 having a relatively long length cannot be gently bent in the storage groove 12 in a low temperature environment, and the optical fiber Transmission loss may increase.

  The thickness δ of the tape core wire is preferably 0.27 mm ≦ δ ≦ 0.33 mm due to restrictions on the equipment for connecting the tape core wires. It is also conceivable to secure the clearance C by uniformly reducing the thickness δ1, δi, δn of the tape core wire within this range. However, when the thicknesses δ1, δi, and δn of all the tape core wires are uniformly reduced, the tape core wires 20 arranged on the outermost side in the radial direction of the slot rod 10 as shown in a comparative example described later. There is a problem that the loss increase α1 and the loss increase αn of the tape core wire 20 arranged on the innermost side in the radial direction of the slot rod 10 are larger than the loss increase αi of other tape core wires.

  In the present invention, the loss characteristics in a low temperature environment can be achieved while making the diameter of the slot type optical cable 1 smaller than the conventional one by making the depth h of the storage groove and the thickness of each laminated tape core wire 20 appropriate. Can be maintained.

Specifically, the thickness δ1 of the tape core wire 20 disposed on the outermost side in the radial direction of the slot rod 10 and the thickness δn of the tape core wire 20 disposed on the innermost side in the radial direction of the slot rod 10 are specifically described. Is made thicker than the thickness δi of other tape cores. Accordingly, it is possible to secure the rigidity of the tape core wire 20 that is disposed on the outermost and innermost side in the radial direction of the slot rod 10 and easily increases loss in a lower temperature environment, and the intermediate tape core wire is thinned. By doing so, the clearance can be secured.
Hereinafter, the present invention will be described in more detail with reference to examples.

<Thickness difference and loss>
Using the slot-type optical cable 1 in which the thickness of the tape core wire 20 was changed and 10 sheets were stacked and accommodated in the slot 12 of the slot rod 10, the value of increase in low-temperature loss during the temperature characteristic test was examined.
The optical fiber 21 used for the tape core wire 20 is a standard single mode optical fiber having a zero dispersion wavelength in the 1.3 μm band, and the loss when it is wound 100 turns around a mandrel with a diameter of 30 mm so as not to vary. When A (dB / φ30 mm × 100 turns), those having bending properties such that A ≦ 5 were selected and used.
The value of the increase in low-temperature loss is a value obtained by subtracting the loss at normal temperature (20 ° C.) from the maximum loss when the slot type optical cable is measured for 18 hours in an environment of −30 ° C.

Hereinafter, the thickness of the tape core wire 20 is set to δ1, δ2,..., Δ9, δ10 in order from the one arranged radially outside the slot rod 10, and the stack height of the tape core wires (δ1 + δ2 +. + Δ9 + δ10) is defined as δs. Further, the increase in the loss of the amount of light transmitted by the tape core wire in a low temperature environment is assumed to be α1, α2,..., Α9, α10 in order from the one arranged outside the slot rod 10. The outer diameter of the slot rod 10 is ds.
As the tape core wire 20, an optical fiber 21 having a diameter of 0.25 mm and eight cores arranged in a row was used.

[Example 1]
ds was 20.3 mm, δ1 and δ10 were 0.32 mm, δ2 to δ9 were 0.28 mm, δs was 2.88 mm, h was 3.40 mm, C was 0.52 mm, and β was 0.72.
[Comparative Example 1]
ds was 20.3 mm, δ1 to δ10 were 0.30 mm, δs was 3.00 mm, h was 3.40 mm, C was 0.40 mm, and β was 0.75.

<Result>
The results are shown in Table 1.

In Example 1, α1 = 0.127 (dB / km), α2 = 0.030 (dB / km), α9 = 0.073 (dB / km), α10 = 0.120 (dB / km). became.
In Comparative Example 1, α1 = 0.227 (dB / km), α2 = 0.040 (dB / km), α9 = 0.080 (dB / km), α10 = 0.183 (dB / km). became.

  From Comparative Example 1, even if the thickness δ of the tape cores is the same, the loss increase (α1, α10) of the outermost and innermost tape cores is the loss increase of other tape cores ( It can be seen that it is larger than α2, α9). In addition, it can be seen from the comparison between Example 1 and Comparative Example 1 that the increase in loss increases α2 and α9 is small by reducing the thicknesses δ2 and δ9 of the tape core wires located outside the outermost side and other than the innermost side. . Further, when δ2 to δ9 are thinned to ensure the clearance, and the tape core wires disposed on the outermost and innermost sides in the radial direction of the slot rod 10 are made thicker than the other tape core wires (Example 1) ), It was possible to increase the loss increase (α1, α10) of the tape core wires arranged on the outermost and innermost sides of the slot rod 10 in the radial direction. In addition, the variation from the loss increase (α2, α9) of other tape cores could be further reduced.

  As described above, when the tape core wires arranged on the outermost and innermost sides in the radial direction of the slot rod 10 are made thicker than other tape core wires, the thickness of all the tape core wires is made equal. It can be seen that the increase in loss is reduced and the variation in loss increase is reduced.

Next, in order to study by changing the outer diameter ds of the slot rod 10, the depth h of the storage groove, and the number of stacked layers, the value of increase in low temperature loss during the temperature characteristic test was examined.
In the following, the number of stacked tape cores is n, the thickness of the tape core 20 disposed on the outermost side in the radial direction of the slot rod 10 is δ1, and the tape is disposed on the innermost side in the radial direction of the slot rod 10. The thickness of the core 20 is δn, and the thickness of the other core 20 (medium tape thickness) is δi (i = 2, 3,..., N−1). (Δ1 + (n−2) δi + δn) is δs, the groove depth of the storage groove 12 is h, the clearance (h−δs) is C, and the space factor (cross-sectional area / storage of the laminated tape cores 20) Let β be the cross-sectional area of the groove 12. Further, α1 represents an increase in low-temperature loss of the tape core wire 20 disposed on the outermost side in the radial direction of the slot rod 10, and αn represents an increase in low-temperature loss on the tape core wire 20 disposed on the innermost side in the radial direction of the slot rod 10. The maximum one of α1 and αn is the maximum loss αmax.

<10 stacked sheets>
The number n of the laminated tape cores 20 was set to 10, and the increase in low-temperature loss in the following examples and comparative examples was measured.
[Example 2]
ds was 20.3 mm, δ1 and δn were 0.29 mm, δi was 0.27 mm, h was 3.40 mm, C was 0.66 mm, and β was 0.69.
Example 3
ds was 20.3 mm, δ1 and δn were 0.33 mm, δi was 0.29 mm, h was 3.4 mm, C was 0.42 mm, and β was 0.75.
Example 4
ds was 20.3 mm, δ1 was 0.33 mm, δn was 0.31 mm, δi was 0.29 mm, h was 3.4 mm, C was 0.44 mm, and β was 0.74.
Example 5
ds was 19.9 mm, δ1, δn was 0.29 mm, δi was 0.27 mm, h was 3.20 mm, C was 0.46 mm, and β was 0.73.
Example 6
ds was 19.9 mm, δ1 and δn were 0.33 mm, δi was 0.29 mm, h was 3.20 mm, C was 0.22 mm, and β was 0.80.
Example 7
ds was 19.9 mm, δ1 was 0.33 mm, δn was 0.31 mm, δi was 0.29 mm, h was 3.20 mm, C was 0.24 mm, and β was 0.79.

[Comparative Example 1]
ds was 20.3 mm, δ1, δi, and δn were 0.30 mm, h was 3.40 mm, C was 0.40 mm, and β was 0.75.
[Comparative Example 2]
ds was 20.3 mm, δ1, δi, and δn were 0.33 mm, h was 3.40 mm, C was 0.10 mm, and β was 0.83.
[Comparative Example 3]
ds was 19.9 mm, δ1, δi, and δn were 0.27 mm, h was 3.20 mm, C was 0.50 mm, and β was 0.72.
[Comparative Example 4]
ds was 19.9 mm, δ1, δi, and δn were 0.30 mm, h was 3.20 mm, C was 0.20 mm, and β was 0.80.

Example 2 and Example 5, Example 3 and Example 6, Example 4 and Example 7, Comparative Example 1 and Comparative Example 4 have the same conditions for the thickness δ1, δi, and δn of the tape core wire 20, respectively. However, the outer diameter ds of the slot rod 10 is changed. Further, Example 3 and Comparative Example 2 are obtained by changing only δi, and Example 5 and Comparative Example 3 are obtained by changing only δ1 and δn.
In addition, the comparative example 1 is the same optical cable as the comparative example 1 shown in Table 1, and both the thickness of the tape core wire 20 of the comparative example 1 and the comparative example 4 is the same as the tape core wire conventionally used widely It is.

<Result>
The results are shown in Table 2.

In Example 2, α1 = 0.114 (dB / km), αn = 0.117 (dB / km), and αmax = 0.117 (dB / km).
In Example 3, α1 = 0.144 (dB / km), αn = 0.136 (dB / km), and αmax = 0.144 (dB / km).
In Example 4, α1 = 0.138 (dB / km), αn = 0.148 (dB / km), and αmax = 0.148 (dB / km).
In Example 5, α1 = 0.215 (dB / km), αn = 0.182 (dB / km), and αmax = 0.215 (dB / km).
In Example 6, α1 = 0.229 (dB / km), αn = 0.221 (dB / km), and αmax = 0.229 (dB / km).
In Example 7, α1 = 0.218 (dB / km), αn = 0.245 (dB / km), and αmax = 0.245 (dB / km).

In Comparative Example 1, α1 = 0.227 (dB / km), αn = 0.183 (dB / km), and αmax = 0.227 (dB / km).
In Comparative Example 2, α1 = 0.301 (dB / km), αn = 0.276 (dB / km), and αmax = 0.301 (dB / km).
In Comparative Example 3, α1 = 0.332 (dB / km), αn = 0.198 (dB / km), and αmax = 0.332 (dB / km).
In Comparative Example 4, α1 = 0.414 (dB / km), αn = 0.294 (dB / km), and αmax = 0.414 (dB / km).

  From the comparison between Example 2 and Example 5, Example 3 and Example 6, Example 4 and Example 7, when δ1−δi ≧ 0.02 mm and δn−δi ≧ 0.02 mm, the slot rod It can be seen that even when the outer diameter ds of 10 is reduced, the increase in the maximum loss is suppressed. On the other hand, in the comparison between Comparative Example 1 and Comparative Example 4, it is found that when δ1 = δi = δn, the maximum loss is remarkably increased when the outer diameter ds of the slot rod 10 is reduced.

  Further, it can be seen from the comparison between Example 3 and Comparative Example 2 that the maximum loss is reduced by reducing δi. Further, the comparison between Example 5 and Comparative Example 3 shows that the thicknesses of the tape cores 20 at both ends are simply smaller than the thicknesses δ1, δi, δn of all the tape cores 20 are reduced (Comparative Example 3). It can be seen that the maximum loss decreases when only the thickness δi of the intermediate tape core wire 20 is made smaller than the thicknesses δ1 and δn.

<15 sheets stacked>
Using the slot type optical cable 1 having the shape as shown in FIG. 4, the increase in the low-temperature loss in the example and the comparative example when the number n of the laminated tape cores 20 is 15 was measured. When the number n of stacked layers is 15, as shown in FIG. 4, it is necessary to form the storage groove 12 formed in the slot rod 10 deeper. In FIG. 4, eight storage grooves 12 are formed in the slot rod 10.
Example 8
ds was 17.9 mm, δ1, δn was 0.29 mm, δi was 0.27 mm, h was 4.70 mm, C was 0.61 mm, and β was 0.72.
Example 9
ds was 17.9 mm, δ1 and δn were 0.33 mm, δi was 0.29 mm, h was 4.7 mm, C was 0.27 mm, and β was 0.77.
Example 10
ds was 17.9 mm, δ1 was 0.33 mm, δn was 0.31 mm, δi was 0.29 mm, h was 4.7 mm, C was 0.29 mm, and β was 0.77.
Example 11
ds was 17.5 mm, δ1 and δn were 0.29 mm, δi was 0.27 mm, h was 4.50 mm, C was 0.41 mm, and β was 0.73.
Example 12
ds was 17.5 mm, δ1 and δn were 0.33 mm, δi was 0.29 mm, h was 4.50 mm, C was 0.07 mm, and β was 0.79.
Example 13
ds was 17.5 mm, δ1 was 0.33 mm, δn was 0.31 mm, δi was 0.29 mm, h was 4.50 mm, C was 0.09 mm, and β was 0.79.

[Comparative Example 5]
ds was 17.5 mm, δ1, δi, and δn were 0.27 mm, h was 4.50 mm, C was 0.45 mm, and β was 0.73.
[Comparative Example 6]
ds was 17.9 mm, δ1, δi, and δn were 0.30 mm, h was 4.7 mm, C was 0.20 mm, and β was 0.79.

In Examples 8 and 11, Example 9 and Example 12, Example 10 and Example 13, the outer diameter of the slot rod 10 while the thicknesses δ1, δi and δn of the tape core wire 20 are set to the same conditions, respectively. ds is changed. In Example 11 and Comparative Example 5, only δ1 and δn are changed.
The thickness of the tape core of Comparative Example 6 is the same as that of a conventionally used tape core.

<Result>
The results are shown in Table 3.

In Example 8, α1 = 0.120 (dB / km), αn = 0.123 (dB / km), and αmax = 0.123 (dB / km).
In Example 9, α1 = 0.174 (dB / km), αn = 0.159 (dB / km), and αmax = 0.174 (dB / km).
In Example 10, α1 = 0.165 (dB / km), αn = 0.190 (dB / km), and αmax = 0.190 (dB / km).
In Example 11, α1 = 0.252 (dB / km), αn = 0.203 (dB / km), and αmax = 0.252 (dB / km).
In Example 12, α1 = 0.293 (dB / km), αn = 0.265 (dB / km), and αmax = 0.293 (dB / km).
In Example 13, α1 = 0.278 (dB / km), αn = 0.512 (dB / km), and αmax = 0.212 (dB / km).

In Comparative Example 5, α1 = 0.369 (dB / km), αn = 0.341 (dB / km), and αmax = 0.369 (dB / km).
In Comparative Example 6, α1 = 0.384 (dB / km), αn = 0.264 (dB / km), and αmax = 0.384 (dB / km).

  From the comparison of Example 8 and Example 11, Example 9 and Example 12, Example 10 and Example 13, when δ1−δi ≧ 0.02 mm and δn−δi ≧ 0.02 mm, the slot rod It can be seen that the increase in the maximum loss is suppressed even when the outer diameter ds of 10 is reduced.

  Further, the comparison between Example 11 and Comparative Example 5 shows that the thickness of the tape cores 20 at both ends rather than simply reducing the thicknesses δ1, δi, and δn of all the tape cores 20 (Comparative Example 5). It can be seen that the maximum loss decreases when only the thickness δi of the intermediate tape core wire 20 is made smaller than the thicknesses δ1 and δn.

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, in the above embodiment, the case where the number n of stacked layers is 10 or 15 has been described, but the present invention is not limited to this, and the number of stacked layers can be arbitrarily set.

It is sectional drawing which shows the slot type optical cable 1 which concerns on embodiment of this invention. FIG. 6 is an enlarged cross-sectional view showing a tape core wire 20 accommodated in a storage groove 12. It is an expanded sectional view which shows the tape core wire 20 accommodated in the substantially U-shaped accommodation groove | channel 12. FIG. 2 is a cross-sectional view showing a slot-type optical cable 1 in which 15 tape core wires 20 are stacked in one storage groove 12. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Slot type optical cable 10 Slot rod 11 Tension member 12 Storage groove 20 Tape core wire 21 Optical fiber 22 Covering material 30 Pressing winding 40 Sheath

Claims (5)

A slot rod having a storage groove formed on the outer periphery;
A plurality of optical fibers arranged in a row and collectively covered, and a tape core wire accommodated in the accommodation groove in a state where n (n is an integer of 3 or more) are laminated in the radial direction of the slot rod. And
The thickness of the tape core wire arranged on the outermost side in the radial direction of the slot rod and the thickness of the tape core wire arranged on the innermost side in the radial direction of the slot rod are larger than the thicknesses of other tape core wires. A slot-type optical cable characterized by being thick. The diameter of the optical fiber is 0.24 to 0.26 mm,
The thickness δ1 of the tape core wire disposed on the outermost side in the radial direction of the slot rod,
The thickness δn of the tape core disposed in the radially inner side of the slot rod, and the i-th (i is an integer of 2 to n−1) tape cores from the radially outer side of the slot rod The slot type optical cable according to claim 1, wherein the thickness δi has the following relationship.
0.29mm ≦ δ1 ≦ 0.33mm
0.29mm ≦ δn ≦ 0.33mm
0.27 mm ≦ δi ≦ 0.29 mm
δ1-δi ≧ 0.02mm
δn−δi ≧ 0.02 mm   The slot type optical cable according to claim 2, wherein n ≧ 10. The difference C between the depth of the storage groove and the stack height of the tape core is 0 ≦ C ≦ 0.7 mm
The slot-type optical cable according to claim 2 or 3, wherein Space factor β is 0.65 ≦ β ≦ 1
The slot type optical cable according to any one of claims 2 to 4, wherein

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