KR102422348B1 - Tape core and optical cable - Google Patents

Abstract

The covering member 2 covers a plurality of parallel optical fiber core wires 1 at once. Each of the plurality of optical fiber core wires 1 is provided with an optical fiber 1a, a covering 1c, and a marking 1e. The covering 1c covers the periphery of the optical fiber 1a. The marking 1e is applied to the outer peripheral surface of the covering 1c. The thickness of the covering member 2 is determined so that the dimension T1 in the direction orthogonal to the parallel direction and the longitudinal direction of the plurality of optical fiber core wires 1 is 0.32 mm or less.

Description

Tape core and optical cable {TAPE CORE AND OPTICAL CABLE}

The present invention relates to a tape core having a plurality of optical fiber cores. Moreover, this invention relates to the optical cable provided with a some tape core wire.

In the tape core wire described in Patent Document 1, a plurality of parallel optical fiber core wires are collectively covered with a resin coating member. Each of the plurality of optical fiber core wires is provided with an optical fiber and a coating covering the outer peripheral surface of the optical fiber. In the tape core wire described in Patent Document 1, in order to improve the discrimination between the plurality of optical fiber core wires, a part of the outer peripheral surface of the coating in the longitudinal direction is marked.

[Prior art literature]

[Patent Literature]

(Patent Document 1) International Publication No. 2013/039766

The lateral pressure applied to the optical fiber is different between the marked area and the non-marked area. Therefore, microbend loss occurs in the longitudinal direction of the optical fiber, and transmission loss may increase. In particular, in the case of a configuration in which a plurality of optical fiber core wires are collectively covered with a resin coating member, like the tape core wire described in Patent Document 1, the increase in transmission loss becomes more remarkable.

A first object of the present invention is to suppress an increase in transmission loss of a tape core having a configuration in which a plurality of marked optical fiber cores are collectively covered with a covering member.

A second object of the present invention is to suppress an increase in transmission loss of an optical cable having a tape core having a configuration in which a plurality of marked optical fiber core wires are collectively covered with a covering member.

In order to achieve the first object, a first aspect that the present invention can take is as a tape core wire,

a plurality of optical fiber core wires in parallel;

A covering member for collectively covering the plurality of optical fiber core wires

is equipped with

Each of the plurality of optical fiber core wires,

optical fiber and

a coating covering the periphery of the optical fiber;

Marking applied to the outer circumferential surface of the coating

is equipped with

The thickness of the covering member is determined so that the dimension of the plurality of optical fiber core wires in the direction orthogonal to the parallel direction and the longitudinal direction is 0.32 mm or less.

In order to achieve the second object, the second aspect that the present invention can take is an optical cable,

a spacer having a plurality of slots;

Multiple tape cores

is equipped with

Each of the plurality of tape core wires,

a plurality of optical fiber core wires in parallel;

A covering member for collectively covering the plurality of optical fiber core wires

is equipped with

Each of the plurality of optical fiber core wires,

optical fiber and

a coating covering the periphery of the optical fiber;

Marking applied to the outer circumferential surface of the coating

is equipped with

In the first portion in the longitudinal direction of each of the plurality of slots, the plurality of tape core wires are stacked and arranged in a parallel direction and a direction perpendicular to the longitudinal direction of the plurality of optical fiber core wires,

In the second portion of each of the plurality of slots in the longitudinal direction, the stacking arrangement is not maintained.

According to the configuration according to the first aspect described above, it is possible to suppress an increase in transmission loss of a tape core having a configuration in which a plurality of marked optical fiber core wires are collectively covered with a covering member.

According to the structure according to the second aspect, it is possible to suppress an increase in transmission loss of an optical cable having a tape core having a configuration in which a plurality of marked optical fiber cores are collectively covered with a covering member.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows the structure of the optical fiber core wire which concerns on embodiment.
2 is a view showing a cross section of a tape core wire according to the first embodiment.
3 is a view showing a cross section of a tape core according to a comparative example.
It is a figure which shows the cross section of the tape core wire which concerns on 2nd Embodiment.
Fig. 5 is a view showing a cross section of a tape core wire according to a third embodiment.
6 is a diagram showing the configuration of a tape core wire according to the fourth embodiment.
7 is a view showing a method of marking the optical fiber core wire.
It is a figure which shows an example of the optical cable provided with the said tape core wire.
Fig. 9 is a view showing another example of an optical cable including the tape core wire.
FIG. 10 is a view showing an enlarged cross section of a part of the optical cable of FIG. 9 .
Fig. 11 is a view showing a modified example of a spacer included in the optical cable of Fig. 9;

Embodiments according to the present invention are enumerated and described below.

(1) : As a tape core wire,

a plurality of optical fiber core wires in parallel;

A covering member for collectively covering the plurality of optical fiber core wires

is equipped with

Each of the plurality of optical fiber core wires,

optical fiber and

a coating covering the periphery of the optical fiber;

Marking applied to the outer circumferential surface of the coating

is equipped with

The thickness of the covering member is determined so that the dimension of the plurality of optical fiber core wires in the direction orthogonal to the parallel direction and the longitudinal direction is 0.32 mm or less.

According to such a structure, the force generated by thermal contraction at the time of processing of the resin which forms a covering member can be reduced. Accordingly, it is possible to suppress an increase in the transmission loss of the tape core wire marked with the optical fiber core wire.

(2): As the tape core wire according to (1),

A part of the covering member positioned between the plurality of adjacent optical fiber core wires is recessed along the outer peripheral surface of the plurality of optical fiber core wires.

According to this configuration, since the cross-sectional area of the covering member can be made as small as possible, the force generated due to thermal shrinkage during processing of the resin forming the covering member can be further reduced. Moreover, since the flexibility of the whole tape core wire can be improved, the bending stress which arises when winding a tape core wire around a bobbin, etc. can be reduced. Accordingly, it is possible to suppress an increase in the transmission loss of the tape core wire.

(3): As the tape core wire according to (2),

The plurality of adjacent optical fibers are intermittently separated from each other in the longitudinal direction.

According to such a structure, bending stress which arises when winding a tape core wire around a bobbin, etc. can be disperse|distributed by displacing a part of each optical fiber core wire. Accordingly, it is possible to suppress an increase in the transmission loss of the tape core wire.

(4): The tape core wire according to any one of (1) to (3),

The thickness of the marking is 5 μm or less.

According to this configuration, the lateral pressure applied to the optical fiber with the marking therebetween can be reduced as much as possible. Accordingly, it is possible to suppress an increase in the microbend loss of the optical fiber core wire due to a force generated by thermal shrinkage during processing of the resin forming the covering member. Accordingly, it is possible to suppress an increase in the transmission loss of the tape core wire.

(5): The tape core wire according to any one of (1) to (4),

The plurality of optical fiber core wires includes a plurality of optical fiber core wires having different positions of the markings in the longitudinal direction of the optical fiber core wires.

According to this configuration, the position where the contracting force applied from the covering member covering the plurality of optical fiber core wires collectively is applied to the optical fiber with the marking therebetween can be different from each other in the longitudinal direction of the tape core wire. Thereby, the lateral pressure applied to the optical fiber through the marking can be dispersed in the longitudinal direction of the tape core wire, and local concentration of stress can be avoided. Accordingly, it is possible to suppress an increase in the transmission loss of the tape core wire.

(6): The tape core wire according to any one of (1) to (5),

The coating is

a primary coating covering the optical fiber;

Secondary coating covering the primary coating

contains,

The Young's modulus of the primary coating is 0.8 MPa or less.

According to such a configuration, it is possible to effectively reduce the lateral pressure applied to the optical fiber with the marking interposed therebetween. Accordingly, it is possible to suppress an increase in the transmission loss of the tape core wire due to the micro-bend loss of the optical fiber core wire.

(7): As an optical cable,

The tape core wire according to any one of (1) to (6);

a tube accommodating the tape core wire;

a sheath covering the periphery of the tube

is provided.

According to this structure, since the tape core wire which can suppress an increase in transmission loss is provided, the increase in transmission loss of an optical cable can also be suppressed.

(8): As an optical cable,

a spacer having a plurality of slots;

Multiple tape cores

is equipped with

Each of the plurality of tape core wires,

a plurality of optical fiber core wires in parallel;

A covering member for collectively covering the plurality of optical fiber core wires

is equipped with

Each of the plurality of optical fiber core wires,

optical fiber and

a coating covering the periphery of the optical fiber;

Marking applied to the outer circumferential surface of the coating

is equipped with

In the first portion in the longitudinal direction of each of the plurality of slots, the plurality of tape core wires are stacked and arranged in a parallel direction and a direction orthogonal to the longitudinal direction of the plurality of optical fiber core wires,

In the second portion of each of the plurality of slots in the longitudinal direction, the stacking arrangement is not maintained.

In the case where an optical cable is wound around a drum, stress is continuously applied in one direction to a plurality of tape core wires arranged in a stacked arrangement. When this stress acts on the optical fiber as a side pressure, the transmission loss of each tape core wire and by extension, an optical cable may increase. However, as mentioned above, in a part of the longitudinal direction of an optical cable, the direction of the stress applied to each tape core wire in this part can be made uneven by breaking the lamination|stacking arrangement of a plurality of tape core wires positively. Therefore, the stress accumulation in one direction in the case where an optical cable is wound on a drum etc. is eliminated, and it can suppress the increase in the transmission loss of each tape core wire and by extension, an optical cable.

(9): The optical cable according to (8),

The plurality of slots extend along the longitudinal direction of the spacer to form an SZ twist.

According to this structure, it is easy to make the direction of the stress applied to the some tape core wire accommodated in each slot not even with respect to the longitudinal direction of an optical cable. Therefore, the stress accumulation in one direction in the case where an optical cable is wound on a drum etc. can be eliminated more reliably, and the increase in the transmission loss of each tape core wire and by extension, an optical cable can be suppressed.

(10): The optical cable according to (8) or (9),

The thickness of the covering member is determined so that the respective dimensions of the plurality of tape core wires in the parallel direction and the direction orthogonal to the longitudinal direction are 0.32 mm or less.

According to this configuration, it is possible to reduce the force generated due to thermal shrinkage during processing of the resin forming the covering member. Thereby, the increase in the transmission loss of a tape core wire can be suppressed, and by extension, the increase in the transmission loss of an optical cable can be suppressed.

(11): The optical cable according to any one of (8) to (10),

A part of the covering member positioned between the plurality of adjacent optical fiber core wires is recessed along the outer peripheral surface of the plurality of optical fiber core wires.

According to such a configuration, since the cross-sectional area of the covering member can be made as small as possible, the shrinkage force of the resin forming the covering member can be further reduced. Moreover, the flexibility of the whole tape core wire can be improved. Therefore, an increase in the transmission loss of the tape core wire can be suppressed, and by extension, an increase in the transmission loss of the optical cable can be suppressed.

(12): The optical cable according to (11),

The plurality of adjacent optical fibers are intermittently separated from each other in the longitudinal direction.

According to such a configuration, bending stress generated in the tape core wire can be dispersed when a part of each optical fiber core wire is displaced. Therefore, an increase in the transmission loss of the tape core wire can be suppressed, and by extension, an increase in the transmission loss of the optical cable can be suppressed.

(13): The optical cable according to any one of (8) to (12),

The thickness of the marking is 5 μm or less.

According to this configuration, the lateral pressure applied to the optical fiber with the marking therebetween can be reduced as much as possible. Accordingly, it is possible to suppress an increase in the microbend loss of the optical fiber core wire due to the contracting force of the covering member. Therefore, an increase in the transmission loss of the tape core wire can be suppressed, and by extension, an increase in the transmission loss of the optical cable can be suppressed.

(14): The optical cable according to any one of (8) to (13),

The coating is

a primary coating covering the optical fiber;

Secondary coating covering the primary coating

contains,

The Young's modulus of the primary coating is 0.8 MPa or less.

According to such a configuration, it is possible to effectively reduce the lateral pressure applied to the optical fiber with the marking interposed therebetween. Accordingly, it is possible to suppress an increase in the transmission loss of the tape core due to the micro-bend loss of the optical fiber core, and furthermore, it is possible to suppress an increase in the transmission loss of the optical cable.

A more specific example of an embodiment according to the present invention will be described in detail below with reference to the accompanying drawings. In addition, in each figure used for the following description, in order to make each element into a recognizable size, the scale is changed suitably.

1 is a diagram showing the configuration of an optical fiber core wire 1. As shown in FIG. Fig. 1(A) shows the appearance of a part of the two optical fiber core wires 1 viewed from a direction orthogonal to the longitudinal direction thereof. Fig. 1(B) shows a cross section of one optical fiber core wire 1 cut along the line IB-IB in Fig. 1(A). In this specification, a "cross-section" means the cross-section of the optical fiber core wire 1 seen from the longitudinal direction.

As shown in Fig. 1B, the optical fiber core 1 includes an optical fiber 1a. The optical fiber 1a is made of, for example, quartz glass or plastic. Although not shown, the optical fiber 1a includes a core and a clad. The core is disposed at the center in the radial direction and has a first refractive index. The clad covers the periphery of the core and has a second refractive index lower than the first refractive index.

The optical fiber core wire 1 is provided with the primary coating|cover 1b (an example of a coating|cover). The primary coating 1b covers the optical fiber 1a. The primary coating 1b is made of, for example, an ultraviolet curable resin.

The optical fiber core wire 1 is provided with the secondary coating|cover 1c (an example of a coating|cover). The secondary coating 1c covers the primary coating 1b. The secondary coating 1c is made of, for example, an ultraviolet curable resin that is harder than the primary coating 1b.

The optical fiber core wire 1 is provided with the coloring ink layer 1d (an example of a coating|cover). The coloring ink layer 1d covers the periphery of the secondary coating 1c. The coloring ink layer 1d is formed so that a predetermined color may be shown in order to distinguish the some optical fiber core wire 1 comrades. The coloring ink layer 1d is formed over the entire length direction of the optical fiber core wire 1 . The coloring ink layer 1d may be omitted if necessary.

As shown in Figs. 1A and 1B, the optical fiber core 1 is provided with a marking 1e. The marking 1e is applied to a part in the longitudinal direction of the optical fiber core wire 1 so as to exhibit a predetermined color. Specifically, by discretely or continuously forming dots of 0.2 to 0.4 mm in diameter showing a predetermined color, the dimension of each marking 1e along the longitudinal direction of the optical fiber core wire 1 is 20 for easy visibility. ~40 mm.

In this example, the marking 1e is implemented so as to cover a part of the outer peripheral surface of the secondary coating 1c between the secondary coating 1c and the coloring ink layer 1d. However, the marking 1e may be implemented so that a part of the outer peripheral surface of the coloring ink layer 1d may be covered. Alternatively, the marking 1e may be implemented so as to cover a part of the outer peripheral surface of the primary coating 1b between the primary coating 1b and the secondary coating 1c.

In addition to or instead of the coloring ink layer 1d, the marking 1e is implemented in order to identify the some optical fiber core wire 1 comrades. For example, in the example shown in FIG. 1A, two optical fiber core wires 1 are distinguished by the number of markings 1e. The distinction between the plurality of optical fiber core wires 1 can be made by at least one of the number, color, position, and dimension of the optical fiber core wire 1 in the longitudinal direction of the markings 1e.

Fig. 2 shows a cross section of the tape core 10 according to the first embodiment. The tape core 10 includes a plurality of optical fiber core wires 1 . Each of the plurality of optical fiber core wires 1 is the same as that described with reference to FIG. 1 , but illustration of the coloring ink layer 1d is omitted.

The plurality of optical fiber core wires 1 are parallel to each other in a direction orthogonal to the longitudinal direction. The diameter d of each optical fiber core wire 1 is 0.25 mm, for example. In this example, the four optical fiber core wires 1 are arranged in parallel, however, the number of optical fiber core wires 1 included in the tape core 10 can be appropriately determined to be two or more.

The tape core wire 10 is provided with the covering member 2 . The covering member 2 covers the plurality of optical fiber core wires 1 at once. The covering member 2 consists of any one of an ultraviolet curable resin, a thermoplastic resin, and a thermosetting resin, for example.

The inventor examines the cause of the significant increase in transmission loss in the tape core wire in which the optical fiber core wire is marked, and the force generated by thermal contraction during processing of the resin forming the covering member (hereinafter , called contractile force) acted on the marking and thought that the microbend loss of the optical fiber core wire was increased. Therefore, the inventor considered that appropriate selection of the thickness of the covering member contributes to suppression of the increase in microbend loss, and measured the contracting force of the covering member and the transmission loss of the tape core wire while changing the thickness of the covering member. As a result of repeated examination, since the thickness of the covering member in which suppression of an increase in transmission loss can be found was found, it describes below.

Specifically, the loss in transmission of light having a wavelength of 1550 nm was measured. The contractile force of the covering member was determined as the product of the cross-sectional area of the covering member, the Young's modulus of the resin forming the covering member, the coefficient of linear expansion of the resin, and the temperature difference between the temperature at the time of processing and the room temperature. Here, the Young's modulus was 910 MPa, the coefficient of linear expansion was 1.5 × 10 ^-4 , and the temperature at the time of processing was 45°C (the difference from room temperature was 22°C).

Fig. 3 shows a cross section of a tape core 10X according to a comparative example. The tape core 10X includes a plurality of optical fiber core wires 1 arranged in parallel. The structure of each optical fiber core wire 1 is the same as that described with reference to FIG. 2 . The tape core wire 10X is provided with the covering member 2X which coat|covers the some optical fiber core wire 1 collectively. In this comparative example, the thickness of the covering member 2X is determined so that the dimension T0 of the tape core wire 10X in the direction orthogonal to the parallel direction and the longitudinal direction of the plurality of optical fiber core wires 1 is 0.40 mm. have.

In this condition, the transmission loss and the contractile force were measured by the method described above, and the following numerical values were obtained.

Transmission loss: 0.20-0.50 dB/km

Contraction force: 0.73N

On the other hand, in this embodiment shown in FIG. 2, the covering member 2 is such that the dimension T1 of the tape core 10 in the direction orthogonal to the parallel direction and the longitudinal direction of the plurality of optical fiber core wires 1 is 0.32 mm. ) has a fixed thickness.

In this condition, the transmission loss and the shrinkage stress were measured by the method described above, and the following numerical values were obtained. Compared with the tape core wire 10X according to the comparative example, it was found that the contracting force of the covering member was reduced and the transmission loss was suppressed.

Transmission loss: 0.18-0.30 dB/km

Shrinkage stress: 0.43N

Therefore, according to the structure of this embodiment, the increase in the transmission loss of the tape core wire 10 in which the marking 1e was given to the optical fiber core wire 1 can be suppressed. It is thought that the suppression of micro-bend loss of the optical fiber core wire 1 because the shrinkage force of the resin forming the covering member 2 can be reduced contributes to suppression of an increase in the transmission loss of the tape core wire 10 . .

Fig. 4 shows a cross section of the tape core wire 10A according to the second embodiment. About the same or equivalent element as the element with which the tape core wire 10 which concerns on 1st Embodiment is equipped, the same reference number is attached|subjected, and repeated description is abbreviate|omitted.

The tape core wire 10A is provided with the covering member 2A. The covering member 2A collectively covers a plurality of parallel optical fiber core wires 1 . The thickness of the covering member 2A is determined so that the dimension T2 of the tape core wire 10A in the direction orthogonal to the parallel direction and the longitudinal direction of the plurality of optical fiber core wires 1 is 0.29 mm.

In this condition, the transmission loss and the contractile force were measured by the method described above, and the following numerical values were obtained. It was found that compared with the tape core wire 10 according to the first embodiment, the contracting force of the covering member is further reduced, and the transmission loss is further suppressed.

Transmission loss: 0.18-0.19 dB/km

Shrinkage stress: 0.33N

Therefore, according to the structure of this embodiment, the transmission loss of the tape core wire 10A in which the marking 1e was given to the optical fiber core wire 1 can be suppressed further.

The inventor considered that appropriate selection of the shape of the covering member in addition to the appropriate selection of the thickness of the covering member contributed to suppression of the increase in microbend loss. Then, the shrinkage stress of the covering member and the transmission loss of the tape core wire were measured while changing the shape of the covering member. As a result of repeated examination, since the shape of the covering member in which suppression of an increase in transmission loss can be found was found, it describes below.

5 : has shown the cross section of the tape core wire 10B which concerns on 3rd Embodiment. About the same or equivalent element as the element with which the tape core wire 10 which concerns on 1st Embodiment is equipped, the same reference number is attached|subjected, and repeated description is abbreviate|omitted.

The tape core wire 10B is provided with the covering member 2B. The covering member 2B covers a plurality of parallel optical fiber core wires 1 at once. The thickness of the covering member 2B is determined so that the dimension T3 of the tape core wire 10B in the direction orthogonal to the parallel direction and the longitudinal direction of the plurality of optical fiber core wires 1 is 0.28 mm. Further, a part of the covering member 2B positioned between the plurality of adjacent optical fiber core wires 1 is recessed along the outer peripheral surface of each optical fiber core wire 1 .

In this condition, the transmission loss and the contractile force were measured by the method described above, and the following numerical values were obtained. It was found that the shrinkage stress of the covering member was further reduced as compared with the tape core wire 10A according to the second embodiment.

Transmission loss: 0.18-0.19 dB/km

Shrinkage stress: 0.15N

According to this configuration, since the cross-sectional area of the covering member 2B can be made as small as possible, it is possible to suppress an increase in the microbend loss of the optical fiber core wire 1 due to the shrinkage stress. Moreover, the flexibility of the whole tape core wire 10B can be improved. Thereby, the bending stress which arises when winding the tape core wire 10B around a bobbin, etc. can be reduced, and the increase in the transmission loss of the tape core wire 10B can be suppressed.

Fig. 6 shows a tape core wire 10C according to the fourth embodiment. Fig. 6(A) shows the external appearance as viewed from the direction orthogonal to the longitudinal direction of a part of the tape core wire 10C. Fig. 6B is a cross section taken along the line VIB-VIB in Fig. 6A. About the same or equivalent element as the element with which the tape core wire 10B which concerns on 3rd Embodiment is equipped, the same reference number is attached|subjected, and repeated description is abbreviate|omitted.

In the present embodiment, the plurality of optical fiber core wires 1 collectively covered by the covering member 2B are intermittently spaced apart in the longitudinal direction thereof. That is, a part of each optical fiber core wire 1 can be displaced relative to another optical fiber core wire 1 .

According to such a configuration, bending stress generated when the tape core wire 10C is wound on a bobbin, etc. can be dispersed when a part of each optical fiber core wire 1 is displaced. Therefore, an increase in the transmission loss of the tape core wire 10C can be suppressed.

In each of the above embodiments, the thickness of the marking 1e is 5 µm or less.

According to this configuration, the lateral pressure applied to the optical fiber 1a with the marking 1e interposed therebetween can be reduced as much as possible. Accordingly, it is possible to suppress an increase in the microbend loss of the optical fiber core wire 1 due to the shrinkage stress of the covering members 2 (2A, 2B). Therefore, an increase in the transmission loss of the tape core wires 10 (10A, 10B, 10C) can be suppressed.

In performing the marking 1e in each of the above embodiments, first, as shown in FIG. 7A , a plurality of optical fiber core wires 1 are arranged in parallel. Then, as shown in Fig. 7B, the marking 1e is collectively applied to the plurality of optical fiber core wires 1 in parallel. The positions at which the marking 1e is applied coincide with the longitudinal direction of each optical fiber core wire 1 . Thereafter, the plurality of optical fiber core wires 1 subjected to the marking 1e are collectively covered with the covering members 2 (2A, 2B). According to this method, application of the marking 1e can be performed efficiently.

As shown in FIG.7(C), the position where the marking 1e is performed may be different from each other in the longitudinal direction of each optical fiber core wire 1 .

According to such a configuration, the shrinkage stress applied from the covering members 2 (2A, 2B) covering the plurality of optical fiber core wires 1 at once is applied to the optical fiber 1a with the marking 1e interposed therebetween. The applied position may be different from each other in the longitudinal direction of the tape core wire 10 (10A, 10B, 10C). Thereby, the lateral pressure applied to the optical fiber 1a with the marking 1e interposed therebetween can be dispersed in the longitudinal direction of the tape core wires 10 (10A, 10B, 10C), and the local concentration of the stress can be reduced. can be avoided Therefore, an increase in the transmission loss of the tape core wires 10 (10A, 10B, 10C) can be suppressed.

As in the example shown in Fig. 7C, the positions of the markings 1e do not have to be different for all the optical fiber core wires 1 included in the tape core wires 10 (10A, 10B, 10C). At least one set of a plurality of optical fiber core wires 1 having different positions of the marking 1e in the longitudinal direction may be included in the tape core 10 (10A, 10B, 10C).

In each of the above embodiments, the Young's modulus of the primary coating 1b is 0.8 MPa or less.

According to this configuration, it is possible to effectively reduce the lateral pressure applied to the optical fiber 1a with the marking 1e interposed therebetween. Therefore, it is possible to suppress an increase in the transmission loss of the tape core 10 (10A, 10B, 10C) due to the micro-bend loss of the optical fiber core wire 1 .

In addition, as an index regarding the inner pressure, the bending loss that increases each time the tape core 10 ( 10A, 10B, 10C) according to each of the above embodiments is wound around a bobbin having a diameter of 15 mm is 0.01 dB. to be below. In addition, after immersing the tape core wires 10 (10A, 10B, and 10C) according to the above embodiments in water at 60° C. for 30 days, the change in the transmission loss value of light having a wavelength of 1550 nm is from the value before immersion in water. It should be less than 0.1 dB/km.

8 : has shown the cross section of the optical cable 20 provided with the tape core wire 10 which concerns on 1st Embodiment. The optical cable 20 has a tube 21 and a sheath 22 .

The tube 21 extends along the longitudinal direction of the optical cable 20 and accommodates the tape core 10 . The tube 21 is made of polyethylene or polybutyl terephthalate, for example. In the illustrated example, five tape core wires 10 are accommodated in the tube 21 , but the number of the tape core wires 10 may be arbitrarily determined according to the specifications of the optical cable 20 . Instead of the tape core wire 10 , one of the tape core wires 10A, 10B, and 10C described above may be accommodated in the tube 21 . The gap 23 between the tape core 10 and the tube 21 may be filled with a filler such as resin or gel.

The sheath 22 extends along the longitudinal direction of the optical cable 20 and covers the periphery of the tube 21 . The shell 22 is made of polyvinyl chloride or polyethylene, for example.

According to this structure, since the tape core wire 10 (10A, 10B, 10C) which can suppress an increase in transmission loss is provided, the increase in transmission loss of the optical cable 20 can also be suppressed.

9 : has shown the cross section of the optical cable 30 provided with the tape core wire 10 which concerns on 1st Embodiment. The optical cable 30 has a spacer 31 and a sheath 32 . The spacer 31 extends along the longitudinal direction of the optical cable 30 and has a plurality of slots 31a. The plurality of slots 31a are formed along the longitudinal direction of the optical cable 30 on the outer peripheral surface of the spacer 31 . A plurality of tape core wires 10 are accommodated in each slot 31a.

The sheath 32 extends along the longitudinal direction of the optical cable 30 and covers the periphery of the spacer 31 . The shell 32 is made of, for example, polyvinyl chloride or polyethylene.

As shown in FIG. 10A , in the first part in the longitudinal direction of each slot 31a , the plurality of tape core wires 10 are arranged in parallel and longitudinal directions of the plurality of optical fiber core wires 1 . stacked in a direction orthogonal to Here, the state "in a stacked arrangement" means a state in which both ends of the plurality of optical fiber core wires 1 in the plurality of tape core wires 10 in the parallel direction are aligned.

On the other hand, as shown in Fig. 10B, the stacking arrangement of the plurality of tape core wires 10 is not maintained in the second portion in the longitudinal direction of each slot 31a. Here, the state "in which the stacking arrangement is not maintained" means a state in which the both ends of the plurality of tape core wires 10 are not aligned.

In the case where the optical cable 30 is wound around a drum or the like, stress is continuously applied in one direction to a plurality of tape core wires arranged in a stacked arrangement. When this stress acts on the optical fiber 1a as a lateral pressure, the transmission loss of each tape core wire 10 and, by extension, the optical cable 30 may increase. However, as in this example, in a part of the longitudinal direction of the optical cable 30, by actively breaking the stacking arrangement of the plurality of tape core wires 10, the stress applied to each tape core wire 10 in the corresponding part is The direction can be uneven. Therefore, when the optical cable 30 is wound around a drum, the stress accumulation|storage in one direction is eliminated, and it can suppress the increase in the transmission loss of each tape core wire 10 and the optical cable 30 by extension.

The tape core wire 10 accommodated in each slot 31a may be replaced by any one of the tape core wires 10A, 10B, and 10C described above. Further, from the viewpoint of suppressing an increase in transmission loss of the entire optical cable 30, instead of the tape core 10, the tape core 10X according to the comparative example shown in Fig. 3 is accommodated in each slot 31a. good night.

Although not shown, in the structure shown in FIG. 9, each slot 31a extends in a spiral form along the longitudinal direction of the spacer 31, and forms a unidirectional twist. However, like the spacer 31A according to the modification shown in FIG. 11 , each slot 31a may extend along the longitudinal direction of the spacer 31 to form a so-called SZ twist.

According to this structure, it is easy to make the direction of the stress applied to the some tape core wire accommodated in each slot 31a uneven with respect to the longitudinal direction of the optical cable 30. As shown in FIG. Therefore, when the optical cable 30 is wound on a drum, the stress accumulation in one direction is more reliably eliminated, and the increase in the transmission loss of each tape core wire 10 and, by extension, the optical cable 30 can be suppressed. .

The above embodiments are intended to facilitate understanding of the present invention, and do not limit the present invention. While this invention can be changed and improved without deviating from the meaning, it is obvious that the equivalent is included in this invention.

The content of Japanese Patent Application No. 2014-102393 submitted on May 16, 2014 is used as what constitutes a part of description of this application.

Claims (14)

a plurality of optical fiber core wires in parallel;
A covering member for collectively covering the plurality of optical fiber core wires
is equipped with
Each of the plurality of optical fiber core wires,
optical fiber and
a coating covering the periphery of the optical fiber;
Marking applied to the outer circumferential surface of the coating
is equipped with
The thickness of the covering member is determined such that the dimensions of the plurality of optical fiber core wires in a direction orthogonal to a parallel direction and a longitudinal direction are 0.29 mm or less,
A part of the covering member positioned between the plurality of adjacent optical fiber core wires is recessed along the outer peripheral surface of the plurality of optical fiber core wires,
The plurality of adjacent optical fibers are intermittently spaced apart from each other in the longitudinal direction,
the plurality of optical fiber core wires includes a plurality of optical fiber core wires having different positions of the marking in the longitudinal direction of the optical fiber core wire;
The thickness of the marking is 5㎛ or less
tape core.
delete delete delete delete The method of claim 1,
The coating is
a primary coating covering the optical fiber;
Secondary coating covering the primary coating
contains,
The Young's modulus of the primary coating is 0.8 MPa or less.
tape core.
The tape core wire according to claim 1 or 6;
a tube accommodating the tape core wire;
a sheath covering the periphery of the tube
Optical cable equipped with
delete delete delete delete delete delete delete

Images