JPH08211262A - Multiple optical fiber cable - Google Patents

Abstract

PURPOSE: To sufficiently suppress transmission loss to a lower level by making it possible to reduce the twist applied on coated optical fiber ribbons and the bending in the direction of curving the side edges of the ribbons within the ribbon surfaces. CONSTITUTION: The coated optical fiber ribbons 15 are housed in the grooves of a grooved spacer 11 having the grooves 13 of an S-Z type on its outer periphery and segment type groove members 21 are S-Z twisted around this grooves spacer 11. The coated optical fiber ribbons are housed in these grooves 23. The coated optical fiber ribbons 15 are housed in the grooves 23 in the state of directing the tape surfaces toward the groove bottoms in the central parts in the inverting parts of the grooves 23 and directing the side edges of the ribbons toward the groove bottoms in the inverting parts of the grooves 23.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-core optical fiber cable using a tape-shaped optical fiber core wire.

[0002]

2. Description of the Related Art An optical fiber cable in which a grooved spacer having an SZ type groove formed on the outer periphery is used and an optical fiber core wire is housed in the groove is used for the connection from the groove to the optical fiber. There is an advantage that the core wire can be easily taken out. As a cable of this type in which a tape-shaped optical fiber core wire is used as the optical fiber core wire, the following cable is conventionally known. A cable in which a plurality of tape-shaped optical fiber core wires are stacked in the groove depth direction and housed in the groove (Japanese Patent Laid-Open No. 2-835).
No. 07, JP-A-5-203849). A cable in which a plurality of tape-shaped optical fiber core wires are stacked in the width direction of the groove and housed in the groove (Japanese Patent Laid-Open No. 4-5580).
3 gazette).

[0003]

The tape-shaped optical fiber core is formed by arranging a plurality of optical fibers in parallel on the same plane and applying a common coating to form a tape. Therefore, each optical fiber bends uniformly in the bending direction of the tape surface, and almost no increase in transmission loss occurs.
When bending (edgewise bending) is applied to bend the side edge of the tape within the tape surface, the optical fiber on the inside of the bend is distorted in the compression direction, and the optical fiber on the outside of the bend is bent. Causes strain in the tensile direction, resulting in a large increase in transmission loss.

In a conventional optical fiber cable, a plurality of tape-shaped optical fiber core wires are housed in an SZ type groove in a state in which they are stacked in a certain direction with respect to the direction of the groove. A portion of the optical fiber core wire is always bent in the direction of bending the side edge of the tape. For example, in the above-mentioned cable in which a plurality of tape-shaped optical fiber core wires are stacked in the groove depth direction, each tape-shaped optical fiber core wire is mainly taped at the groove inversion portion (the portion where the spiral direction is inverted). It is bent in the direction that bends the side edge. Further, in the above-mentioned cable in which a plurality of tape-shaped optical fiber core wires are laminated in the width direction of the groove, mainly in the middle part between the reversal parts of the groove (between one reversal part and the next reversal part). It is bent in the direction that bends the side edge of the tape.

As described above, in the optical fiber cable of the type in which the tape-shaped optical fiber core wire is housed in the SZ-shaped groove, since the tape-shaped optical fiber core wire is inevitably subjected to an excessive bending stress, the transmission loss of the optical fiber is increased. It is said that it is difficult to put it into practical use because it not only becomes large, but also has problems in terms of long-term reliability.

In view of the above problems, an object of the present invention is to provide a tape-shaped optical fiber core wire in a multi-core optical fiber cable of a type in which the tape-shaped optical fiber core wire is housed in an SZ type groove. It is an object of the present invention to provide a multi-core optical fiber cable capable of accommodating a large number of tape-shaped optical fiber core wires while solving the problems of bending strain and increase in transmission loss of the optical fiber accompanying it.

[0007]

In order to achieve the above-mentioned object, the multi-core optical fiber cable of the present invention has an SZ type groove in which the spiral direction is periodically reversed within one revolution on the outer periphery. A grooved spacer, a tape-shaped optical fiber core wire housed in the groove of the grooved spacer, and a spiral direction of 1 around the grooved spacer with the groove facing outward.
In the groove of the grooved spacer, there is provided a segment type groove member that is SZ-twisted so as to be periodically inverted within the circumference, and a tape-shaped optical fiber core wire housed in the groove of the segment type groove member. Of the tape-shaped optical fiber and the tape-shaped optical fiber in the groove of the segment-shaped groove member are respectively located at the central portions between the inversion portions of the groove (the central portion between one inversion portion of the groove and the next inversion portion). ), The tape located on the inner side of the bend of the groove of the reversing part when the tape surface is directed to the groove bottom and the tape reversing part is stored in the groove with the tape surface facing the groove bottom. It is characterized in that it is housed in the groove with the side edge facing the groove bottom.

[0008]

It will be described below that the above object can be achieved by such a configuration. 1 and 2 are explanatory views showing the basic configuration of the multi-core optical fiber cable of the present invention. FIG.
(A) schematically shows a cross section of the grooved spacer 11, and (B) schematically shows a side surface of the grooved spacer 11. Reference numeral 13 'is a locus of SZ type grooves formed on the outer periphery of the grooved spacer 11.

2A to 2K are respectively shown in FIG. 1B.
3 is a cross-sectional view taken along line aa-kk of FIG. The cable of the present invention comprises a grooved spacer 11 having an SZ-shaped groove 13 on the outer circumference, and a tape-shaped optical fiber core wire 15 housed in the groove 13 of the grooved spacer. Although many grooves 13 are formed, only one is shown here for the sake of clarity. In this example, three tape-shaped optical fiber core wires 15 are accommodated in the groove 13 in a laminated state. In order to identify each one of the three tape-shaped optical fiber core wires 15 and its orientation, a circle mark and a cross mark are provided on one side of the two outer tape-shaped optical fiber core wires 15.

As shown in FIG. 1B, the groove 13 is formed on the outer periphery of the grooved spacer 11 so that the spiral direction is periodically inverted. Reference numeral 17 is a reversal portion in the spiral direction of the groove, 19 is a central portion between the reversal portions of the groove (a central portion between one reversal portion 17 of the groove and the next reversal portion 17), and P is a reversal pitch of the groove (1 It is the center axis distance of the grooved spacer from one inversion part 17 to the next inversion part 17). Further, in FIG. 1A, θ is a reversal angle of the groove (a rotation angle in the circumferential direction of the grooved spacer from one reversal portion 17 to the next reversal portion 17 of the groove). In this example, θ = 300 °. Although only one inversion pitch from (a) to (k) is shown in FIG. 2, the state from (k) to (a) is reversed at the subsequent one inversion pitch, and this is repeated thereafter. It will be.

At the central portion 19 between the inverted portions of the groove 13, as shown in FIG.
As shown in FIG. 3, the tape-shaped optical fiber core wire 15 is housed in the groove 13 with the tape surface facing the groove bottom.
In FIG. 17, the tape-shaped optical fiber core wire 15 is placed in the groove 13 with the side edge of the tape facing the groove bottom (the tape stands in the groove) as shown in FIGS. 2 (a) and (k). It is stored.
However, in FIGS. 2A and 2K, the direction of the tape-shaped optical fiber core wire 15 is opposite to the direction of the groove 13. That is, in FIG. 2 (a), the side edge of the tape-shaped optical fiber core wire 15 opposite to the mark .circle-circle. Faces the groove bottom, but in FIG. The side edge on the X mark side faces the groove bottom. In this state, the tape-shaped optical fiber core wire 15 is located "inside the bend of the groove of the inversion part" when it is assumed that the tape-shaped optical fiber core wire 15 is accommodated in the groove with the tape surface facing the groove bottom. Is arranged so that the side edge of the tape faces the groove bottom.

The phrase "inside the bend of the groove of the inverted portion" is the portion 17a in FIG. FIG. 3 shows a side surface of a grooved spacer 11 having one SZ spiral groove 13. 17 is groove 13
17a is the inside of the bend of the groove of the reversing part 17, 17b is the outside of the bending of the groove of the reversing part 17, and 19 is the center between the reversing parts.

The tape-shaped optical fiber core wire 15 housed in the groove 13 as described above has the reversing portion 17 and the center portion 19 between the reversing portions.
However, it will be bent mainly in the direction of bending the tape surface. Therefore, this state is the state in which the bending of the tape-shaped optical fiber core wire 15 in the direction in which the side edge of the tape is bent in the tape surface is the smallest.

Further, with such a storage method, the twist applied to the tape-shaped optical fiber core wire 15 is reduced. Figure 2
At first glance (a) to (k), it seems that the laminated body of the tape-shaped optical fiber core wires 15 is rotated and twisted in the groove 13, but in reality, from (a) to (d), In the section and the section from (h) to (k), only the direction of the groove 13 changes, but the direction of the tape-shaped optical fiber core wire 15 hardly changes.

This means that no twist is applied to the tape-shaped optical fiber core wire 15 in the above section. Twisting is applied to the tape-shaped optical fiber core 15 only in the section from (d) to (h) (only 120 ° out of 300 ° inversion angle).
Is. In the conventional cable, the tape-shaped optical fiber core is twisted at any position from one inversion part to the next inversion part, but in comparison with this, the cable of the present invention has a tape-shaped optical fiber core. Twist applied to the wire is significantly less (180 ° less in one reversal pitch).

As described above, the bending in the direction in which the side edge of the tape is bent and the reduction in the twist applied to the tape-shaped optical fiber core wire reduce the transmission loss of the optical fiber in the tape-shaped optical fiber core wire. It is effective in reducing the size.

Next, the reversal angle θ of the groove of the grooved spacer will be described. The direction of the groove 13 changes from the state of the tape-shaped optical fiber core wire 15 in which the side edge is directed to the groove bottom to the state of FIG. 2 (a) in which the tape surface is directed to the groove bottom (d). 90 °
Need to rotate. Similarly, from the state of (h) to the state of (k), the direction of the groove 13 must be rotated by 90 °. In other words, in order to obtain a state in which the tape-shaped optical fiber core wire 15 directs the tape side edge toward the groove bottom at the groove inversion portion and the tape surface toward the groove bottom at the center portion between the groove inversion portions, The orientation of the grooves on each side of the part must be rotated at least 90 ° in the circumferential direction of the grooved spacer.

Therefore, the reversal angle θ of the groove 13 of the grooved spacer 11 must be 180 ° or more. By the way, θ = 180
“°” is a state in which the twist is not applied to the tape-shaped optical fiber core wire. The upper limit of the reversal angle θ of the groove 13 is preferably 360 ° or less. If the reversal angle of the groove is 360 ° or more, the ease of taking out the tape-shaped optical fiber core wire from the groove is impaired. Considering the ease of taking out the tape-shaped optical fiber from the groove, the reversal angle of the groove should be 360 ° or less. Therefore, the reversal angle of the groove is usually set to an appropriate value within the range of 180 ° to 360 °. The preferred range of groove reversal angle is 210 ° to 330 °, and more preferred range is 270 ° to 300 °.
°.

The relationship between the direction of the groove 13 and the direction of the tape-shaped optical fiber core 15 shown in FIGS. 2A to 2K is in an ideal state. Actually, the tape-shaped optical fiber core wire 15 has the groove 13
Since it is free inside, the direction changes to the most stable state in the groove 13 due to its elasticity, rigidity, bending force at the reversing portion, or the like. Specific examples thereof are shown in FIGS. 4 (a) to 4 (k) are respectively aa of FIG. 1 (B).
It is sectional drawing in a line-kk line.

At the central portion 19 between the inverted portions of the groove 13, as shown in (f), the tape-shaped optical fiber core wire 15 is housed in the groove 13 with the tape surface facing the groove bottom. This point is the same as in the case of FIG. In the example of FIG. 4, the direction of the groove 13 from (f) is
When rotated by 90 °, that is, in (c) and (i), the tape-shaped optical fiber core wire 15 becomes almost upright in the groove 13,
Further, in the reversing portion 17 of the groove 13, as shown in (a) and (k), the tape-shaped optical fiber core wire 15 is in a state of falling from the upright state toward the inside of the bending of the groove of the reversing portion 17. In the present invention, "the tape-shaped optical fiber core wire is accommodated in the groove with the side edge of the tape facing the groove bottom at the inversion portion of the groove" is shown in FIG.
It also includes states such as (a) and (k).

As shown in FIG. 5, the cable of the present invention further includes a segment type groove member 21 which is SZ-twisted around the grooved spacer 11 with the groove 23 facing outward, and the groove 23 of the segment type groove member. And a tape-shaped optical fiber core wire 25 housed inside. 5A to 5K are cross-sectional views corresponding to FIGS. 2A to 2K, respectively. Although the segment-shaped groove members 21 are twisted in a large number, only one is shown here for the sake of clarity. In the case of FIG. 2, the groove 23 accommodates three tape-shaped optical fiber core wires 15 in a stacked state, and one side of the outer two tape-shaped optical fiber core wires 15 is marked with a circle and a cross. Is the same as.

Since the segment type groove member 21 is SZ-twisted with the groove 23 facing outward, the spiral direction of the groove 23 is periodically reversed. Since the reversal pitch of the segment groove member 21 is usually different from the reversal pitch of the groove 13 of the grooved spacer 11, the reversal portion of the groove 23 of the segment groove member 21 and the reversal portion of the groove 13 of the grooved spacer 11 are long. It is normal to shift in the direction.

Also in the case of the segment type groove member 21, the tape-shaped optical fiber core wire 25 is shown in FIG.
In the state in which the tape surface is directed to the groove bottom as in (f), and in the inverted portion of the groove 23, the tape side edge is directed to the groove bottom as shown in FIGS. It is housed in a groove 23, while standing inside. That is, it is stored in the same state as in FIG. Therefore, as in the case of FIG.
Bending in the direction of bending the side edge of the tape, which is applied to the tape-shaped optical fiber core wire, and twisting are reduced, and an increase in transmission loss of the optical fiber in the tape-shaped optical fiber core wire can be reduced.

The reversal angle of the groove 23 of the segment groove member 21 (the reversal angle of the SZ twist of the segment groove member 21) is selected similarly to the reversal angle θ of the groove of the grooved spacer.

The relationship between the direction of the groove 23 and the direction of the tape-shaped optical fiber core wire 25 shown in FIGS. 5A to 5K is in an almost ideal state. Actually, it may be as shown in FIGS. 6A to 6K are respectively shown in FIG.
It is sectional drawing corresponding to (a)-(k). That is, the groove
When the direction of the groove 23 is rotated by 90 ° from the central portion (f) between the reversing portions of 23, the tape-shaped optical fiber core wire 25 becomes almost upright in the groove 23 at the positions (c) and (i). In some cases, the tape-shaped optical fiber core wire 25 in the reversal portions (a) and (k) may fall from the upright state toward the inside of the bend of the groove of the reversal portion. The present invention also includes such a case.

Since the cable of the present invention can accommodate the tape-shaped optical fiber core wires not only in the groove of the grooved spacer as described above but also in the groove of the segment groove member, a large number of tape-shaped optical fiber core wires can be accommodated. It can be stored.

Next, the dimensions of the grooved spacer and the groove of the segment groove member will be described. In order to obtain a state in which the tape surface faces the groove bottom and a state in which the tape side edge faces the groove bottom in the groove of the tape-shaped optical fiber core, Among these, it is preferable that the direction can be relatively changed without breaking the laminated state. On the other hand, it is extremely difficult to change the cross-sectional dimension of the groove in the longitudinal direction from the viewpoint of manufacturing the grooved spacer or the segment groove member. Therefore, if the size of the groove is constant over the entire length, the size of the groove is preferably determined as follows. That is, as shown in FIG. 7, when the width of the tape-shaped optical fiber core wire 15 is W, the thickness is T, and the number of laminated layers is N, the width B and the depth D of the groove 13 of the grooved spacer 11 are as follows. Set so as to satisfy the formula (the same applies to the groove 23 of the segment type groove member 21).

[0028]

[Formula 1] B, D ≧ {W ² + (NT) ² } ^1/2

By doing so, the width B and the depth D of the groove 13 are larger than the length L of the diagonal line of the laminated body of the tape-shaped optical fiber core wires 15, so that the tape-shaped optical fiber core wire is inside the groove 13. It is possible to relatively change the direction of the laminated body of 15 without breaking the laminated state and without generating excessive stress.

The tape-shaped optical fiber core wire 15 is shown in FIG.
As shown in (A), a plurality of optical fibers 31 are arranged on one plane and a common coating 33 is applied. Taking a tape-shaped optical fiber core having four cores as an example, a stack of the tape-shaped optical fiber cores 15 is laminated. The relationship between the number of sheets and the dimensions is as shown in FIGS.
Tape-shaped optical fiber core wire housed in segment-type groove member
The case of 25 is the same as this.

[0031]

FIG. 9 and FIG. 10 show a first embodiment of the present invention. This multi-core optical fiber cable is provided with a grooved spacer 11 at the center. The grooved spacer 11 is an extruded product of polyethylene having an SZ type groove 13 in which the spiral direction is periodically reversed on the outer periphery, and a steel twist wire tension member 35 is embedded in the center thereof. In this example, eight grooves 13 are formed at equal intervals. A tape-shaped optical fiber core wire 15 is housed in the groove 13 as shown in FIG. In Figure 9, the groove
In order to clarify the inversion angle of 13, the tape-shaped optical fiber core wire 15 is shown stored in only one groove 13, but the tape-shaped optical fiber core wire 15 is also similarly provided in the other grooves 13. Is stored.

FIG. 9 (A) is a cross-sectional view of one inversion portion of the groove 13 [corresponding to FIG. 4 (a)], and FIG. 9 (C) is a cross-sectional view of the next inversion portion of the groove 13 [FIG. 4 (c)]. FIG. 4B is a cross-sectional view [corresponding to FIG. 4B] at the central portion between the reversal portions of the groove 13. That is, the tape-shaped optical fiber core wire 15 is a groove.
At the central portion between the reversal portions of 13 the tape surface faces the groove bottom as shown in FIG. 9 (B), and at the reversal portion of the groove 13 the tape side edges face the groove bottom as shown in (A) and (C). (Precisely speaking, the side edge of the tape located inside the bend of the reversing part faces the groove bottom when it is stored in the groove with the tape surface facing the groove bottom.) It is stored in 13.

A press winding 37 is provided on the outer periphery of the grooved spacer 11 accommodating the tape-shaped optical fiber core wire 15.
A segment-shaped groove member 21 made of a polyethylene extruded body is provided on the outer periphery of the press winding 37 with the groove 23 facing outward.
Z twisted. In this example, the number of segment-type groove members 21 is 16. In the groove 23 of the segment type groove member 21,
As shown in FIG. 10, a tape-shaped optical fiber core wire 25 is stored. In FIG. 10, in order to clarify the reversal angle of the SZ twist of the segment groove member 21, one segment groove member is used.
Although the tape-shaped optical fiber core wire 25 is stored only in 21, the tape-shaped optical fiber core wire 25 is also stored in the other segment groove members 21 in the same manner.

FIG. 10 (A) is a sectional view of one reversal portion of the segment type groove member 21 (which is also the reversal portion of the groove 23) [corresponding to FIG. 6 (a)], and FIG. 10 (C) is the segment type groove member. 6 is a cross-sectional view of the next inverted portion of 21 [corresponding to FIG. 6 (c)], and FIG. 6 (B) is a cross-sectional view of the central portion between the inverted portions of the segment groove member 21 [corresponding to FIG. 6 (b)]. That is, the tape-shaped optical fiber core wire 25 is formed in the center portion between the inversion portions of the groove 23 as shown in FIG.
As shown in (B), the tape surface faces the groove bottom, and at the reversal portion of the groove 23, the tape side edges face the groove bottom as shown in (A) and (C). It is housed in the groove 23 so that the side edge of the tape located on the inner side of the bend of the groove of the reversal portion faces the groove bottom when it is assumed to be housed in the groove while facing the groove bottom).

A press winding 39 is applied to the outer periphery of the segment type groove member 21, and a sheath 41 is applied to the outer periphery thereof (however, the illustration of the sheath is omitted in (A) and (C)). The same cable is shown separately in FIG. 9 and FIG. 10, except that the inverted portion of the groove 13 of the grooved spacer 11 and the groove of the segment type groove member 21 are shown.
This is because the inverted portion of 23 is displaced in the longitudinal direction.

The multi-core optical fiber cable of this embodiment has the above-mentioned structure. The dimensions of each part of the cable prototyped with this configuration are as follows. The outer diameter of the grooved spacer 11 is about 16 mm, and the cross-sectional dimensions of the groove 13 are a groove bottom width of 1.3 mm, a groove top width of 4.5 mm, and a groove depth of 2.3 mm. The reversal angle of groove 13 is about
300 °, reversal pitch is about 240 mm. Two tape-shaped optical fiber core wires 15 were stacked and housed in each of the eight grooves 13. The dimensions of the laminated body 15 of the two tape-shaped optical fiber cores are as shown in FIG. 8 (B). The outer diameter in the state where the press winding 37 is applied is about 18 mm.

On the other hand, the outer dimensions of the segment-type groove member 21 are 3.5 mm in bottom width, 4.5 mm in top width, and 2.0 mm in height.
The cross-sectional dimensions of 23 are 2.0 mm in groove width and 1.4 mm in groove depth.
The reversal angle of SZ twist of the segment type groove member 21 is about 250 °,
The reverse pitch is about 500 mm. In each groove 23, two tape-shaped optical fiber core wires 25 are stacked and housed. The dimensions of the tape-shaped optical fiber core wire 25 are the same as those of the tape-shaped optical fiber core wire 15 housed in the grooved spacer 11.

The multi-core optical fiber cable as described above was prototyped, and the tape-shaped optical fiber core wire 15 was housed in the groove 13 of the grooved spacer 11 and the press winding 37 was wound (the central unit step), and The segment type groove member 21 is SZ-twisted on top, the tape-shaped optical fiber core wire 25 is housed in the groove 23 and the press winding 39 is wound (outer layer gathering step), and the sheath 41 is applied on it. At the sheath stage), the transmission loss of each tape-shaped optical fiber core wire was measured. The measurement wavelength is 1.55 μm. Table 1 shows the results.

[0039]

[Table 1]

Since the target value of transmission loss is 0.25 dB / km or less on average, it was confirmed that this cable has sufficient performance.

Next, FIGS. 11 and 12 show a second embodiment of the present invention. FIG. 11 corresponds to FIG. 9 of the first embodiment, and FIG.
12 also corresponds to FIG. This embodiment is different from the first embodiment in that the grooved spacer 11 has five grooves and the segmented groove member 21 has ten grooves. The other structure is the same as that of the first embodiment, and therefore the same parts are denoted by the same reference numerals and the description thereof is omitted.

The dimensions of each part of this cable are as follows. The outer diameter of the grooved spacer 11 is about 11 mm, and the cross-sectional dimensions of the groove 13 are 2.0 mm in groove width and 1.4 mm in groove depth. The reversal angle of the groove 13 is about 290 °, and the reversal pitch is about 250 mm. The same two tape-shaped optical fiber cores as in Example 1 are provided in each groove 13.
Fifteen were stacked and stored.

On the other hand, the outer dimensions of the segment-type groove member 21 are 3.5 mm in bottom width, 4.5 mm in top width, and 2.0 mm in height.
The cross-sectional dimensions of 23 are 2.0 mm in groove width and 1.4 mm in groove depth.
The reversal angle of SZ twist of the segment type groove member 21 is about 250 °,
The reverse pitch is about 500 mm. In each groove 23, the same two tape-shaped optical fiber core wires 25 as in Example 1 were stacked and housed.

When a multi-fiber optical fiber cable as described above was prototyped and the same test as in Example 1 was conducted, the results shown in Table 2 were obtained, and it was confirmed that the optical fiber cable had sufficient performance.

[0045]

[Table 2]

In the above-mentioned embodiments, the laminated body of the tape-shaped optical fiber core wire is stored in the groove of the grooved spacer and the segment type groove member as it is.
As shown in, the laminated body of the tape-shaped optical fiber core wire 15,
With the cushioning protective tape 43 made of foamed plastic or the like attached to the side surface of the grooved spacer 11,
It is also possible to have a structure in which the tape-shaped optical fiber core wire 25 is housed in the groove 23 of the segment-type groove member 21. In this way, the side edge of the tape-shaped optical fiber core wire 15 is not directly pressed against the groove bottom or groove wall, which is effective in suppressing an increase in transmission loss.

In the above embodiments, the grooved spacer has been described as an integral unit, but in the grooved spacer, a large number of segment type groove members are SZ-twisted around the central tensile member with the grooves facing outward. It can also consist of things. Further, in the laminated body of the tape-shaped optical fiber cores housed in the groove of the grooved spacer, since the tape-shaped optical fiber cores are not constrained to each other, the laminated state may be somewhat collapsed.

[0048]

As described above, according to the present invention, S
In an optical fiber cable of a type in which a tape-shaped optical fiber core wire is housed in a Z-shaped groove, a twist applied to the tape-shaped optical fiber core wire and a bending in a direction in which a side edge of the tape is curved in the tape surface are provided. Since it can be made small, the transmission loss of the tape-shaped optical fiber core wire can be suppressed sufficiently small. Further, since the tape-shaped optical fiber core wire can be stored in the groove of the grooved spacer and the groove of the segment-type groove member, a large number of tape-shaped optical fiber core wires can be stored and a cable having a large number of optical fiber cores can be stored. Can be configured.

Further, since the segment type groove member is SZ-twisted with the groove facing outward, the tape-shaped optical fiber core wire can be easily taken out from the groove. Further, since it is easy to remove the segment groove member from around the grooved spacer, it is also easy to take out the tape-shaped optical fiber core wire from the groove of the grooved spacer. Therefore, it is easy to handle when connecting cables, branching connections, or performing terminal processing.

[Brief description of drawings]

FIG. 1 is a schematic view showing a grooved spacer used in a multi-fiber optical fiber cable of the present invention, in which (A) is a cross section and (B) is a side view.

2 (a) to (k) respectively show an example of the relationship between the direction of the groove of the grooved spacer in the cable of the present invention and the direction of the tape-shaped optical fiber core wire; FIG.
Sectional drawing in kk line.

FIG. 3 is a side view showing a groove form of a grooved spacer used in the present invention.

4 (a) to (k) show another example of the relationship between the direction of the groove of the grooved spacer and the direction of the tape-shaped optical fiber core wire in the cable of the present invention, respectively, and FIG. Sectional drawing in the line to kk line.

5 (a) to 5 (k) are cross-sectional views each showing an example of the relationship between the groove direction of the segment groove member and the tape optical fiber core wire in the cable of the present invention.

6 (a) to 6 (k) are cross-sectional views each showing another example of the relationship between the groove direction of the segment groove member and the tape-shaped optical fiber core wire in the cable of the present invention.

FIG. 7 is a cross-sectional view showing the relationship between the dimensions of the groove of the grooved spacer used in the present invention and the dimensions of the tape-shaped optical fiber core wire.

8A to 8D are cross-sectional views each showing a laminated state of a tape-shaped optical fiber core wire.

9A and 9B show a first embodiment of a multi-fiber optical fiber cable according to the present invention. FIGS. 9A and 9C are cross-sectional views of a groove inversion portion of a grooved spacer, and FIG. 9B is a central portion between the inversion portions. FIG.

FIG. 10 (A) and (C) similarly showing the first embodiment.
Is a cross-sectional view of an inverted portion of the groove of the segment-type groove member,
(B) is a cross-sectional view of the central portion between the reversing portions.

FIG. 11 shows a second embodiment of the multi-core optical fiber cable according to the present invention, (A) and (C) are cross-sectional views of the groove inversion portion of the grooved spacer, and (B) is a central portion between the inversion portions. FIG.

FIG. 12 (A) (C) also shows a second embodiment.
Is a cross-sectional view of an inverted portion of the groove of the segment-type groove member,
(B) is a cross-sectional view of the central portion between the reversing portions.

FIG. 13 is a cross-sectional view showing an example of a structure for housing the tape-shaped optical fiber core wire in the groove in the multi-core optical fiber cable of the present invention.

[Explanation of symbols]

11: Spacer with groove 13: SZ-shaped groove 13 ': Locus of groove 13 15: Tape-shaped optical fiber core 17: Inverted portion of groove 13: Central portion between inverted portions of groove 13 21: Segment groove member 23 : Groove 25: Tape-shaped optical fiber core wire 37, 39: Winding 41: Sheath

Front Page Continuation (72) Inventor Hideyuki Iwata 1-1-6 Uchisaiwai-cho, Chiyoda-ku, Tokyo Japan Telegraph and Telephone Corporation (72) Inventor Mito Matsumoto 1-1-6 Uchiyuki-cho, Chiyoda-ku, Tokyo Japan Inside Telegraph and Telephone Corporation

Claims (1)

[Claims] 1. A grooved spacer having an SZ-shaped groove whose spiral direction is periodically reversed within one circumference on the outer circumference, and a tape-shaped optical fiber core wire housed in the groove of the grooved spacer. A segment type groove member which is SZ-twisted so that the spiral direction is periodically reversed within one turn around the grooved spacer toward the outside, and the segment type groove member is housed in the groove of the segment type groove member. A tape-shaped optical fiber core wire, the tape-shaped optical fiber core wire in the groove of the grooved spacer and the tape-shaped optical fiber core wire in the groove of the segment-shaped groove member, respectively, central portion between the reversal portions of the groove ( It is assumed that the tape surface is oriented toward the groove bottom at one of the inversion portions of the groove to the next inversion portion, and that the tape surface is accommodated in the groove at the inversion portion of the groove with the tape surface facing the groove bottom. When the inside of the bend of the inversion groove A multi-fiber optical fiber cable, characterized in that the tape is stored in the groove with the side edge of the tape positioned facing the groove bottom.