JPH08292348A - Optical fiber cable - Google Patents

Abstract

PURPOSE: To provide an optical fiber cable with which the suppression of skew is possible and the efficiency of cable laying and connection work can be im proved. CONSTITUTION: Plural pieces of plural-fiber optical fiber assemblies 1 are arrayed in a lateral direction and are arranged apart prescribed spacings. Sheaths 2 are clad on their respective outer peripheries and the fiber assembles are integrated by these sheaths 2. The sheaths 2 have a plane structure and have recessed parts 3 formed continuously in the longitudinal direction of the cable on the boundary lines of the adjacent plural-fiber optical fiber assemblies 1. Metallic or nonmetallic tensile bodies 4 are arranged in the sheaths 2 of the boundary parts of the adjacent plural-fiber optical fiber assemblies 1. Tensile fibers 5, such as aramid fibers, are arranged between the front surface parts of the sheaths 2 and the plural-fiber optical fiber assemblies 1. Line marks 6 are continuously applied on the surfaces of the sheaths 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-fiber optical fiber cable, for example, a high-speed, large-capacity interconnecting module device in an information processing device such as an ultra-high-speed computer or a large-capacity electronic exchange. It is used for the wiring system.

[0002]

2. Description of the Related Art Conventionally, a large amount of coaxial cables, which have a smaller transmission capacity than optical fibers, have been used for interconnection between a plurality of module devices constituting a large capacity electronic switch, and thus a large installation space is required. Was. Therefore, it is possible to interconnect the devices by an optical parallel transmission line composed of a plurality of core wires, for example, Ryuichi Matsuoka and three others, "80-core array flat cable", Proceedings of the 1992 Autumn Meeting of the Institute of Electronics, Information and Communication Engineers, B-634 (P.4-27), Toshiaki Ozawa et al., “Reduction of skew of 40-fiber tape fiber”, 1
Proceedings of the 993 IEICE Spring Conference, B-104
7 (P.4-185).

When performing such optical parallel transmission,
If the skew, that is, the difference in delay time between the cores, is large, the signal cannot be transmitted in parallel in the plurality of cores without error. Therefore, in the above-mentioned conventional example, a plurality of all core wires are collectively made into a tape. However, the concrete structure of the cable has not been sufficiently studied, and the efficiency of cable laying and connection work has not been examined.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and in an optical fiber cable, it is possible to suppress skew, improve cable laying and connection work efficiency, and achieve low loss branching. It is an object of the present invention to provide a structure of an optical fiber cable and a manufacturing method thereof that can be achieved.

[0005]

According to a first aspect of the present invention, in an optical fiber cable, a plurality of multi-fiber optical fiber assemblies and a jacket are provided, and the multi-fiber optical fiber assembly is provided. Is arranged in parallel at a predetermined interval, each outer periphery of a multi-core optical fiber assembly is covered with the outer cover, and is integrated by the outer cover, the outer cover is a flat structure. It is an outer shape, and is characterized in that a continuous dent portion is formed in the cable longitudinal direction on the surface on the boundary line between the adjacent multi-core optical fiber assemblies.

According to a second aspect of the invention, in the optical fiber cable according to the first aspect, the jacket is
It is characterized by being a non-combustible or flame-retardant resin.

According to a third aspect of the present invention, in the optical fiber cable according to the first aspect, a part of the outer jacket is provided in a boundary portion between the adjacent multi-fiber optical fiber assemblies. It is characterized by having a strength member.

According to a fourth aspect of the present invention, in the optical fiber cable according to the first aspect, only between one of the upper surface and the lower surface of the jacket and the multi-fiber optical fiber assembly, It is characterized by having a tensile strength fiber.

According to a fifth aspect of the invention, the optical fiber cable according to the first or fourth aspect is characterized in that a line mark is provided on one of the upper surface and the lower surface of the jacket. .

According to a sixth aspect of the present invention, in the optical fiber cable according to the first aspect, the jacket is
When the multi-core optical fiber assembly has an insertion space, the width of the multi-core optical fiber assembly is W, and the thickness of the multi-core optical fiber assembly is T, the multi-core optical fiber assembly The width of the insertion space is 1.1 W or more, and the height of the insertion space of the multi-fiber optical fiber assembly is 2T or more.
It is characterized by being 2T or less.

According to a seventh aspect of the present invention, a plurality of multi-core optical fiber assemblies having a plurality of optical fiber cores are arranged in parallel at predetermined intervals, and are arranged on each outer periphery of the multi-core optical fiber assembly. In an optical fiber cable manufacturing method of covering a jacket and integrating with the jacket to form an outer shape of a flat structure, the plurality of optical fiber core wires are drawn from the same preform, In the above, the difference in relative refractive index difference is 0.02% or less.

According to an eighth aspect of the present invention, in the optical fiber cable manufacturing method according to the seventh aspect, the tension applied to the optical fiber core wire in the manufacturing process of the multi-core optical fiber assembly is set to the optical fiber cable. Set in stages according to the position of the fiber core wire in the multi-core optical fiber assembly, the difference in length of the optical fiber core wire in the multi-core optical fiber assembly, the optical fiber core wire 5m per 1m
It is characterized in that it is set to m or less.

[0013]

According to the first aspect of the present invention, the multi-core optical fiber assembly is arranged in parallel at a predetermined interval, and the outer circumference of each of the multi-core optical fiber assemblies is covered with an outer cover, The outer cover has a flat structure and has a continuous depression in the longitudinal direction of the cable formed on the surface of the boundary line between adjacent multi-core optical fiber assemblies. Therefore, by tearing the jacket along the recess, branching can be easily performed without connecting optical fibers, and wiring can be performed in units of a multi-fiber optical fiber assembly. Therefore, the efficiency of the laying work can be improved, and a low loss branch can be realized.

According to the invention of claim 2, claim 1
In the optical fiber cable described in (1), since the jacket is made of nonflammable or flame retardant resin, it can be used indoors.

According to the invention of claim 3, claim 1
In the optical fiber cable according to the item (1), a part of the outer sheath, which has a tensile strength member in the boundary portion of the adjacent multi-core optical fiber aggregates, prevents temperature expansion and contraction of the resin of the outer sheath. can do.

According to the invention of claim 4, claim 1
In the optical fiber cable according to the item (1), among the upper surface or the lower surface of the jacket, since the tensile strength fiber is provided only between one surface and the multi-fiber optical fiber assembly, an individual multi-fiber optical fiber assembly. When wiring the cable, the tensile strength fiber functions as a tensile strength body, and when winding or bundling in a drum, the surface on the side where the tensile strength fiber is inserted is on the outside, and it is wound in a drum or rounded to form a multi-core fiber. It is possible to prevent the fiber assembly from meandering.

According to the invention of claim 5, claim 1
Alternatively, in the optical fiber cable described in the paragraph 4, since the line mark is provided on one of the upper surface and the lower surface of the jacket, it is possible to visually recognize the twist and correct the laying state, and to prevent skew and transmission loss due to the twist. The increase can be prevented. It is also possible to recognize the side where the tensile strength fiber is inserted.

According to the invention of claim 6, claim 1
In the optical fiber cable described in the item (1), when the jacket has an insertion space for the multi-fiber optical fiber assembly, the width of the multi-fiber optical fiber assembly is W, and the thickness of the multi-fiber optical fiber assembly is T. , The width of the insertion space of the multi-fiber optical fiber assembly,
Since the height of the insertion space of the multi-fiber optical fiber assembly is 1.1 W or more and the height of the insertion space of the multi-fiber optical fiber assembly is 2T or more and 3.2T or less, the bending of the optical fiber core wire in the multi-fiber optical fiber assembly and It is possible to prevent a difference in length of the multi-fiber optical fiber assembly.

According to the invention described in claim 7, optical fibers having a plurality of cores are drawn from the same preform, and the difference in relative refractive index difference between all the cores is 0.02% or less. Therefore, the skew can be reduced.

According to the invention described in claim 8, claim 7
In the method for manufacturing an optical fiber cable according to, the tension applied to the optical fiber core wire in the manufacturing process of the multi-core optical fiber assembly is stepwise according to the position of the optical fiber core wire in the multi-fiber optical fiber assembly. Since the difference between the lengths of the optical fiber cores in the multi-core optical fiber assembly is set to 5 mm or less per 1 m of the optical fiber cores, the skew can be reduced.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a sectional structural view for explaining an embodiment of the optical fiber cable of the present invention. In the figure, 1 is a multi-fiber optical fiber assembly, 2 is a jacket, 3 is a recessed portion, 4 is a tensile strength body,
Reference numeral 5 is a tensile strength fiber, 6 is a line mark, and 7 is an optical fiber insertion space.

The plurality of multi-fiber optical fiber assemblies 1 are, for example, optical fiber tapes. 1 optical fiber tape
A plurality of optical fibers having the next coating are arranged in the width direction and collectively coated, and have a smaller thickness than the width in the left-right direction in the drawing. Multiple multi-fiber optical fiber assembly 1
Are arranged in the left-right direction in the drawing and are arranged at predetermined intervals, and the outer circumference of each is covered with the jacket 2 and
Are integrated by.

As the material of the jacket 2, polytetrafluoroethylene (registered trade name "Teflon") or non-combustible or flame-retardant resin such as polyvinyl chloride is used. Considering that it is used indoors. ing. The outer cover 2 has a flat structure having a thickness smaller than the width in the left-right direction in the drawing, and the upper and lower surfaces of the outer cover 2 are adjacent to each other.
Has a recess 3 formed continuously in the cable longitudinal direction on the boundary line. Adjacent multiple-fiber optical fiber assembly 1
A metal or non-metal strength member 4 is arranged in the outer cover 2 at the boundary portion of the. When the jacket 2 is contracted, the multi-core optical fiber assembly 1 is loosened and the transmission loss is increased. Therefore, the strength member 4 prevents the jacket 2 from expanding and contracting and can withstand the cable laying tension. It retains such cable strength.

A tensile strength fiber 5 such as an aramid fiber is arranged between the upper surface portion of the jacket 2 and the multi-fiber optical fiber assembly 1. The strength of the tensile strength fiber 5 holds the individual multi-fiber optical fiber assembly 1. The tensile strength fiber 5 may be arranged between the lower surface portion of the jacket 2 and the multi-fiber optical fiber assembly 1. Further, it may be arranged both between the upper surface portion of the jacket 2 and the multi-core optical fiber assembly 1 and between the lower surface portion of the jacket 2 and the multi-core optical fiber assembly 1. However, when the tensile strength fibers 5 are arranged on both sides, the optical fiber cable of the embodiment of the present invention is made to have the surface on the side where the tensile strength fibers 5 are inserted inside, in other words, the side where the radius of curvature becomes small. The multi-fiber optical fiber assembly meanders when used in a state of being wound on a drum or bundled in a round shape. As a result, the plurality of multi-fiber optical fiber assemblies 1 have different lengths and skew occurs.

A line mark 6 is continuously formed on the surface of the jacket 2, and the twist can be visually recognized to correct the installed state to a twist-free state. As a result, it is possible to prevent an increase in skew and transmission loss due to twisting. The line mark 6 shown in the figure is located on the extension line of the center upper part of each multi-core optical fiber assembly 1 in the upper surface portion of the jacket 2, and is formed as a linear depression continuous in the longitudinal direction of the cable. ing. Achromatic or chromatic color printing may be performed at the same time as the depression, or only coloring printing may be performed without providing the depression. Indentations and / or colored printing may be applied to the lower surface portion of the jacket 2. Line mark 6
May be formed in the width direction of the cable, and may be continuously formed in the longitudinal direction of the cable at predetermined intervals. Instead of printing the line mark 6, characters may be printed. The line mark 6 can also be used to identify the side where the tensile strength fiber 5 is arranged. It is possible to prevent meandering of the multi-fiber optical fiber assembly by using it in a state of being wound in a drum or being bundled in a round shape with the surface on the side where the tensile strength fiber 5 is inserted facing outward.

FIG. 2 is an explanatory view for explaining the insertion space of the multi-fiber optical fiber assembly. In the figure, the same parts as those in FIG. The jacket 2 shown in FIGS. 1 and 2 does not simply cover the multi-fiber optical fiber assembly 1 but has an optical fiber insertion space 7 for inserting the multi-fiber optical fiber assembly 1. is there. At the same time, the tensile strength fiber 5 is also inserted in this space.

Since the multi-fiber optical fiber assembly 1 is inserted into the optical fiber insertion space 7, a clearance is provided between the multi-fiber optical fiber assembly 1 and the jacket 2. Therefore, due to the contraction of the jacket 2, the optical fibers in the multi-fiber optical fiber assembly 1 are not pushed and bent by the lateral pressure. However, if the optical fiber insertion space 7 is too large, the multi-core optical fiber assembly 1 will move freely, resulting in a difference in the length of the multi-core optical fiber assembly 1, which in turn causes skew. Let In particular,
This effect is great when the height of the insertion space of the multi-fiber optical fiber assembly is increased.

In this case, when the width of the multi-fiber optical fiber assembly is W and the height of the multi-fiber optical fiber assembly is T, the width of the insertion space of the multi-fiber optical fiber assembly is 1.1 W or more. , The height of the insertion space of the multi-fiber optical fiber assembly is 2
It must be T or more and 3.2T or less. When the width of the insertion space of the multi-core optical fiber assembly is less than 1.1 Wmm or the height of the insertion space of the multi-core optical fiber assembly is less than 2 Tmm, the lateral pressure increases the transmission loss of the multi-core optical fiber assembly. . Further, when the height of the insertion space of the multi-fiber optical fiber assembly exceeds 3.2 Tmm, the multi-fiber optical fiber assembly sags in the insertion space, and a difference in length between the multi-fiber optical fiber assemblies occurs. , Cause skew.

Wiring work, such as between the frames of the exchange, using the above-mentioned optical fiber cable will be described. Once you have installed the optical fiber cable,
By tearing along any one of the recesses 3 and the tensile strength member 4, it is possible to easily branch the multi-core optical fiber assembly as a unit and change the wiring destination, thereby improving the efficiency of the laying work. If the cable jacket 2 is made of soft PVC or the like, it can be easily torn by hand, and even if it is hard Teflon or the like, it can be torn by using a knife or the like. Since it is not necessary to connect optical fibers to each other, it is possible to branch with low loss. When wiring the multi-fiber optical fiber assembly 1 of the torn cable, the tensile strength fiber 5 inserted therein functions as a tensile strength body of the cable.

Next, a method of manufacturing the above-mentioned optical fiber cable will be described. Considering parallel transmission, it is necessary to suppress the skew to a certain value or less, but the value is defined as 200 psec / 100 m from the viewpoint of transmission time. Since the cause of the skew is the difference in the optical path length, it is necessary to define the optical fiber length in the optical fiber cable and the relative refractive index difference between the used optical fibers. The optical fiber cable has three steps: an optical fiber manufacturing step, a multi-core optical fiber assembly manufacturing step, and a cable manufacturing step. The difference in optical fiber length is due to the assembly manufacturing process and the cable manufacturing process, and the relative refractive index difference is due to the optical fiber manufacturing process. When the same optical fiber is different only in the optical fiber length, the skew generated per 1 m of the difference in the optical fiber length was 5000 psec / m.

As a control at the time of manufacturing the cable, it is necessary to make the lengths of the multi-fiber optical fiber assembly uniform. Controlling the length must manage the back tension of the multi-fiber optical fiber assembly. In the manufacturing process of the multi-core optical fiber assembly 1, the back tension of the plurality of optical fibers was uniformly set to 50 g. In this case, the optical fiber length is 2
A difference of 6.7 mm / 100 m occurred. This is converted into skew, 5000 × 26.7 = 133.5 pse
It corresponds to c / 100 m. Considering the difference in optical fiber length caused in other steps, this skew is considerably large. As a result of analyzing the cause of the difference in the optical fiber length, the friction generated in the manufacturing line was observed between the central optical fiber whose entrance angle to the optical fiber assembly die was 0 ° and the optical fiber of the outer core with the same angle. Therefore, it was concluded that the central optical fiber has a longer optical fiber length.

Therefore, the back tension of the optical fibers corresponding to both ends of the multi-core optical fiber assembly 1 is set to 50 g, and the back tension of the optical fibers is increased by 20 g each time the fibers are inwardly moved one by one. The length difference was reduced to 4.27 mm / 100 m. Converted to skew, 5000 x 4.27 = 21.35 pse
It corresponds to c / 100 m.

In the step of forming a cable into a plurality of multi-core optical fiber assemblies 1, by giving an equal back tension to the multi-core optical fiber assemblies 1, the skew between the multi-core optical fiber assemblies due to this step is caused. Is theoretically 0
Becomes However, in the structure in which the tensile strength fibers 5 such as aramid fibers are inserted into the upper and lower surfaces of each of the multi-core optical fiber assemblies 1 at the time of manufacturing the cable, in the state where the cables are bundled in a round shape, The difference in length of the assembly 1 was 50 mm / 100 m. When converted into skew, it corresponds to 5000 × 50 = 250 psec.

On the other hand, in the structure in which the tensile strength fiber 5 is inserted only on one surface side of each multi-core optical fiber assembly 1, the surface on the side where the tensile strength fiber 5 is inserted is set to the outside. With the cables bundled in a round shape, the difference in length between the plurality of multi-fiber optical fiber assemblies 1 is 15 mm / 100 m.
Decrease to. If converted into skew, 5000 × 15 = 7
This corresponds to 5 psec / 100 m. The surface of the multi-fiber optical fiber assembly on the side where the tensile strength fiber is not inserted is in contact with the surface of the multi-fiber optical fiber assembly insertion space when bundled.

Further, an optical fiber having a relative refractive index difference of 0.36% and an optical fiber having a relative refractive index difference of 0.38% have a relative refractive index difference of 0.02%. Occurs. The skew per 100 m of the optical fiber length is
It was 100 psec / 100 m.

Therefore, if the relative refractive index difference is suppressed to 0.02% or less, the skew of the optical fiber cable becomes 100.
(Optical fiber) +21.35 (Multi-fiber optical fiber aggregate) +75 (Cable) = 196.35 psec / 1
It becomes 00m and satisfies the target value.

In order to obtain an optical fiber having a relative refractive index difference of 0.02% or less, it is possible to use an optical fiber having a selected relative refractive index difference. However, when a plurality of optical fibers drawn from the same preform were measured, it was found that all satisfy the condition that the difference in relative refractive index difference is 0.02% or less.

However, when the cable is twisted, 50 ps
Since a skew of ec / twist frequency has occurred, a line mark is given on the surface of one side of the cable jacket to prevent cable twist, and to prevent twist wiring, draw the attention of the wiring worker. I have to.

[0039]

According to the present invention, there is an effect that skew can be suppressed, cable laying and connection work can be made more efficient, and a low loss branch can be realized. In information processing equipment such as ultra-high-speed computers and large-capacity electronic exchanges, it is possible to increase the speed and density of the system by using it as a wiring system that interconnects module devices using multiple cores. .

[Brief description of drawings]

FIG. 1 is a sectional structural view illustrating an embodiment of an optical fiber cable of the present invention.

FIG. 2 is an explanatory diagram illustrating an insertion space of a multi-fiber optical fiber assembly.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Multi-fiber optical fiber assembly, 2 ...
4 ... Strength member, 5 ... Strength fiber, 6 ... Line mark, 7
… Optical fiber insertion space.

Claims (8)

[Claims] 1. A plurality of multi-core optical fiber assemblies and a jacket, wherein the multi-core optical fiber assemblies are arranged in parallel at a predetermined interval, and the plurality of multi-core optical fiber assemblies are provided on each outer periphery of the multi-core optical fiber assembly. The outer cover is covered, and is integrated by the outer cover, the outer cover is a flat structure outer surface, on the surface on the boundary line of the adjacent multi-core optical fiber assembly,
An optical fiber cable having a continuous recess formed in the longitudinal direction of the cable. 2. The optical fiber cable according to claim 1, wherein the outer cover is made of non-combustible or flame-retardant resin. 3. The optical fiber cable according to claim 1, wherein a tensile strength member is provided in a boundary portion of the plurality of core optical fiber assemblies which are a part of the outer jacket and are adjacent to each other. 4. The optical fiber cable according to claim 1, wherein tensile strength fibers are provided only between one of the upper surface and the lower surface of the outer cover and the multi-fiber optical fiber assembly. 5. The optical fiber cable according to claim 1 or 4, wherein a line mark is provided on one of an upper surface and a lower surface of the jacket. 6. The outer cover has an insertion space for the multi-fiber optical fiber assembly, the width of the multi-fiber optical fiber assembly is W, and the thickness of the multi-fiber optical fiber assembly is T. At this time, the width of the insertion space of the multi-core optical fiber assembly is
The optical fiber cable according to claim 1, wherein the height is 1.1 W or more and the height of the insertion space of the multi-fiber optical fiber assembly is 2T or more and 3.2T or less. 7. A plurality of multi-core optical fiber assemblies having a plurality of optical fiber core wires are arranged in parallel at a predetermined interval, and each outer circumference of the multi-core optical fiber assembly is covered with a jacket,
In the method for manufacturing an optical fiber cable that is integrated by the jacket and forms the outer shape of a flat structure, the optical fiber core wires of the plurality of cores are drawn from the same preform, and the relative refractive index difference between all the core wires is A method for manufacturing an optical fiber cable, wherein the difference is 0.02% or less. 8. The tension applied to the optical fiber core wire in the manufacturing process of the multi-core optical fiber assembly is set stepwise according to the position of the optical fiber core wire in the multi-core optical fiber assembly. The optical fiber cable manufacturing method according to claim 7, wherein the difference in length of the optical fiber core wires in the multi-core optical fiber assembly is set to 5 mm or less per 1 m of the optical fiber core wires. Method.