JP4032218B2 - Optical closure for plastic optical fiber cable branch - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical closure (branch box) used for branching a plastic optical fiber cable.
[0002]
[Prior art]
When an optical fiber is used as a communication means for a large number of users such as in a building, a multi-core optical fiber cable in which a large number of optical fibers are housed in one cable is used. For example, when branching an optical fiber to each floor in a building, a required number of optical fibers are branched in the middle (non-terminal portion) of a multi-core optical fiber cable. Usually, an optical closure (branch box) is used for this branching part, and the branching part, especially the optical fiber connection part is protected.
[0003]
When a plastic optical fiber is used for the multi-core optical fiber cable, the branching work is easy and useful because the allowable elongation of the optical fiber is large, the fiber is easily cut, and the end face treatment after cutting is easy.
[0004]
[Problems to be solved by the invention]
When a plastic optical fiber is used for a multi-core optical fiber cable, development of a dedicated optical closure utilizing the characteristics of the plastic optical fiber has been demanded. That is, there has been a demand for the development of an optical closure for plastic optical fiber cables that is easy to branch, has a highly reliable structure that does not increase connection loss due to disturbances such as vibration and temperature change, and is small. .
[0005]
[Means for Solving the Problems]
The present invention solves the above problems, and provides an optical closure for a plastic optical fiber cable that is easy to branch, ensures high reliability of a connecting portion, and is small. That is, the present invention includes an optical fiber connecting means for connecting plastic optical fibers, an optical fiber fixing means for fixing the plastic optical fiber in the vicinity of the optical fiber connecting means, the optical fiber connecting means, and the optical fiber fixing means. An optical closure for branching a plastic optical fiber cable comprising an optical fiber connecting portion fixing means made of a material having a linear expansion coefficient substantially equal to that of the plastic optical fiber.
[0006]
By providing the optical fiber fixing means in the vicinity of the optical fiber connection means, the optical fiber connection means can be hardly affected by disturbances such as vibration and temperature change. Further, the optical fiber connecting part fixing means is provided with an optical fiber connecting means and an optical fiber fixing means, and the linear expansion coefficient of the optical fiber connecting part fixing means and the linear expansion coefficient of the plastic optical fiber are made substantially equal to each other. Thus, it is possible to suppress an increase in connection loss in the optical fiber connecting means due to the expansion and contraction of the optical fiber. Here, the linear expansion coefficient of the optical fiber connecting portion fixing means and the plastic optical fiber is substantially equal. Specifically, the linear expansion coefficient A of the optical fiber connecting portion fixing means is set to the linear expansion coefficient of the plastic optical fiber. The value A / B divided by the coefficient B is preferably 0.8 to 1.2.
[0007]
In the present invention, it is preferable that the optical fiber fixing means is configured to press and fix a rubber-like elastic body on a plastic optical fiber. As a result, an increase in loss due to fixing of the optical fiber can be suppressed, and the optical fiber can be securely held.
[0008]
In the present invention, the plastic optical fiber is preferably a fluororesin optical fiber. By combining the fluororesin-based optical fiber and the branching optical closure in the present invention, a low-loss optical fiber and a low-loss connection method for connecting the optical fiber are secured, and hundreds of buildings in buildings where low loss is required. An optical fiber communication means over a meter can be easily secured.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
The branching optical closure of the present invention includes an optical fiber connecting means for connecting plastic optical fibers, an optical fiber fixing means for fixing the plastic optical fiber in the vicinity of the optical fiber connecting means, the optical fiber connecting means, and the optical fiber. And an optical fiber connection portion fixing means made of a material having a linear expansion coefficient substantially equal to that of the plastic optical fiber.
[0010]
FIG. 1 shows a plan view of an example of the branching optical closure of the present invention. In this example, the plastic optical fibers 11 a and 11 b branched from the multi-core optical fiber cable 10 and the plastic optical fibers 21 a and 21 b of the two-core optical fiber cable 20 are connected using the optical fiber connection means 4. . Here, an example of connecting a two-core optical fiber cable is given, but the present invention can also be applied to a connection to a multi-core optical fiber cable such as a single core or four cores. The branching optical closure 1 includes an optical fiber connecting portion fixing means 2, a multi-core optical fiber cable fixing means 12, and a two-core optical fiber cable fixing means 22. The optical fiber connection portion fixing means 2 includes an optical fiber fixing means 3 and an optical fiber connection means 4. Further, the branching optical closure 1 includes a lid (not shown), and by attaching the lid, the branching optical closure is in a substantially sealed state, and the optical fiber connection portion and the like are protected from dust, impact and the like. The two-core optical fiber cable fixing means 22 fixes the tension member 23 and fixes the two-core optical fiber cable 20. The optical fiber fixing means 3 fixes the optical fibers 11a, 11b, 21a, and 21b via the rubber-like elastic body 34.
[0011]
The multi-core optical fiber cable 10 is a multi-core cable of 8 cores, 12 cores, 64 cores, etc., and has a grooved spacer 14 (grooves are not shown). The grooved spacer 14 may be an SZ type spacer (a special spacer in which the spiral direction of the groove is periodically reversed in the middle) or a spacer in which the spiral direction of the groove is unidirectional. If the protective tube 13 is used when the plastic optical fibers 11 a and 11 b are branched from the multi-core optical fiber cable 10, stress may concentrate on the plastic optical fibers 11 a and 11 b at the coated end portion of the multi-core optical fiber cable 10. This is preferable because the plastic optical fibers 11a and 11b are not easily damaged. The multi-core optical fiber cable 10 is fixed to the branching optical closure by the multi-core optical fiber cable fixing means 12. The multi-core optical fiber cable fixing means 12 may be of any method, but the multi-core optical fiber cable twist prevention unevenness (not shown) provided in the branching optical closure 1 may be used in combination with a binding band. Since construction is simple, it is preferable. The plastic optical fibers 11a and 11b may be single-core fibers or tape core wires. The plastic optical fibers 11a and 11b may be covered with bare wires.
[0012]
FIG. 2 is an enlarged view of a fixed portion of the two-core optical fiber cable 20 in FIG. The two-core optical fiber cable 20 includes plastic optical fibers 21 a and 21 b and a tension member (strength member) 23. The two-core optical fiber cable 20 is fixed to the branching optical closure by fixing the tension member 23 to the branching optical closure using the two-core optical fiber cable fixing means 22. In this example, the two-core optical fiber cable 20 is provided with two tension members 23, and the tension member distal end portion 24 is bent and hooked on the two-core optical fiber cable fixing means 22, and then fixed with a screw 25.
[0013]
FIG. 3A shows a front view of an example of the optical fiber fixing means 3, and FIG. 3B shows a top view corresponding to FIG. In this example, the optical fiber fixing means 3 includes an optical fiber receiver 31, an optical fiber fixing lid 32, and a screw 33. The plastic optical fiber 11 is fixed to the optical fiber receiver 31 via a rubber-like elastic body 34. That is, the optical fiber fixing means 3 fixes the rubber-like elastic body 34 to the plastic optical fiber 11 by pressing. Here, the size of the space formed by the optical fiber receiver 31 and the optical fiber fixing lid 32 (depth of the concave portion of the optical fiber receiver 31) is appropriately set according to the size of the rubber-like elastic body 34, and a plastic optical fiber can be easily used. And the loss is not increased due to excessive lateral pressure applied to the plastic optical fiber. The rubber-like elastic body 34 is exemplified as a cylindrical one, but a plastic optical fiber may be sandwiched between two flat-plate-type elastic bodies, and one elastic body 34 having a rectangular space in cross section is used. A plurality of plastic optical fibers may be held in the space, or one elastic body provided with a plurality of plastic optical fiber fixing holes may be employed.
[0014]
FIG. 4 shows a front view of another example of the optical fiber fixing means 3. In this example, an optical fiber receiver 31 and an optical fiber fixing lid 32 are provided. The optical fiber fixing lid 32 has an engaging claw 35, and the optical fiber receiver 31 has a corresponding engaging groove 36. By pushing the optical fiber fixing lid 32 into the optical fiber receiver 31, the optical fiber fixing lid 32 fixes the plastic optical fiber 11 to the optical fiber receiver 31 via the rubber-like elastic body 34.
[0015]
The optical fiber fixing means 3 in the present invention is not limited to the above-described one, and any optical fiber fixing means 3 may be used as long as it has a mechanism that can securely hold the plastic optical fiber without damaging the plastic optical fiber. Good.
[0016]
FIG. 5 shows an assembly diagram of an example of the optical fiber connecting means 4. In this example, the optical fiber connecting means 4 is a simple connector (mechanical splice), and has an upper member 41, a lower member 42, and a clip 43. A V-groove 44 is carved in the lower member 42, and a plastic optical fiber is joined in this groove. In this example, the plastic optical fibers are butt-joined by a mechanical splice, but a refractive index adjusting agent may be used together or may be joined by adhesion. The optical fiber connecting means 4 may employ a connector or the like, but a mechanical splice is preferable in that the connection loss is low, construction is simple, and reconnection is easy.
[0017]
The optical fiber connecting portion fixing means in the present invention comprises the above-described optical fiber fixing means and optical fiber connecting means, and is made of a material having a linear expansion coefficient substantially equal to that of the plastic optical fiber. The fact that the optical fiber connection fixing means has a linear expansion coefficient substantially equal to that of the plastic optical fiber means that the plastic optical fiber between the optical fiber fixing means and the optical fiber connection means expands and contracts due to temperature changes. This is preferable because an increase in connection loss in the fiber connecting means can be suppressed. Regarding the linear expansion coefficient, it is preferable that a value A / B obtained by dividing the linear expansion coefficient A of the optical fiber connection portion fixing means by the linear expansion coefficient B of the plastic optical fiber is 0.8 to 1.2.
[0018]
When a fluororesin optical fiber having a linear expansion coefficient of 7 × 10 ⁻⁵ ° C. ⁻¹ is used as the plastic optical fiber, acrylic resin (7 × 10 ⁻⁵ ° C. ^{− 1} ), polycarbonate resin (7 × 10 ⁻⁵ ° C. ⁻¹ ), polystyrene resin (8 × 10 ⁻⁵ ° C. ⁻¹ ), AS resin (8 × 10 ⁻⁵ ° C. ⁻¹ ) and the like are preferably employed.
[0019]
In FIG. 1, the optical fiber connection fixing means 2 is provided separately from the branching optical closure 1, but a material having a linear expansion coefficient substantially equal to that of the plastic optical fibers 11 and 21 is used as the material of the branching optical closure 1. When employed, the optical fiber connection portion fixing means 2 may be formed integrally with the branching optical closure 1. In this case, the optical fiber fixing means 3 and the optical fiber connecting means 4 are directly fixed to the branching optical closure 1.
[0020]
A specific branching method using the branching optical closure described above will be described below with reference to FIG.
[0021]
The branching optical closure 1 was made by processing an aluminum plate. The size including the lid (not shown) was 37 cm in the longitudinal direction (horizontal direction in the figure), 6 cm in width (vertical direction in the figure), and 4 cm in thickness. As the plastic optical fibers 11 and 21, a fluororesin optical fiber (Asahi Glass Co., Ltd., outer diameter 0.5 mm, trade name: Lucina) having an acrylic resin reinforcing coating layer was used. As the multi-core optical fiber cable, a 64-core cable (outer diameter 20 mm) having an SZ type spacer was used. A two-core optical fiber cable having two plastic optical fibers and two steel tension members 23 was used. The optical fiber connection portion fixing means 2 is made of an acrylic resin having substantially the same linear expansion coefficient as that of the fluororesin optical fiber (linear expansion coefficient: 7 × 10 ⁻⁵ ° C. ⁻¹ ). The plate was 16 cm, the short side was 3 cm, and the thickness was 3.5 mm. As the optical fiber connecting means 4, the mechanical splice shown in FIG. 5 was used. The mechanical splice body (upper member 41, lower member 42) is made of polycarbonate resin, and the clip 43 is made of stainless steel. The mechanical splice body has a long side (longitudinal direction of the V-groove 44) of 2 cm and a short side of 1 cm. The thickness was 6 mm.
[0022]
First, the coating of the multi-core optical fiber cable 10 was removed over 30 cm. Next, the desired plastic optical fibers 11a and 11b to be branched were selected and cut with a nipper. Thereafter, the multi-core optical fiber cable 10 was fixed to the branching optical closure using a binding band. The selected plastic optical fibers 11a and 11b were covered with a protective tube 13 made of polyethylene, and a part of the protective tube 13 was inserted into the groove of the multi-fiber optical fiber cable 10 and fixed.
[0023]
After cutting the cut ends of the plastic optical fibers 11a and 11b with a razor blade to prepare a cut end face, the cut end face is polished with a polishing sheet having a nominal particle diameter of 1 μm and held in the optical fiber fixing means 3 in advance. The plastic optical fibers 11a and 11b were inserted into the cylindrical rubber elastic body 34 made of silicone. At this time, the screw 33 is loosely tightened so that the plastic optical fibers 11 a and 11 b can be easily inserted into the rubber-like elastic body 34. The depth of the recess of the optical fiber receiver 31 of the optical fiber fixing means 3 was 1.2 mm, the outer diameter of the rubber-like elastic body was 2 mm, and the inner diameter was 1 mm.
[0024]
The coating of the two-core optical fiber cable 20 was removed, and the plastic optical fibers 21a and 21b and the tension member 23 were taken out. Next, the tension member 23 was temporarily fixed to the branching optical closure 1 by the two-fiber optical fiber cable fixing means 22. The two-fiber optical fiber cable fixing means 22 includes a screw 25 and a pressing plate, and the screw 25 can be tightened or loosened. Here, the plastic optical fibers 21a and 21b were temporarily fixed so as to be longer. Thereafter, the cut end faces of the plastic optical fibers 21a and 21b were processed in the same manner as the plastic optical fibers 11a and 11b to obtain cut end faces applicable to the butt connection.
[0025]
Next, after the plastic optical fibers 11a and 11b are inserted into the optical fiber connecting means 4 assembled in advance, the plastic optical fibers 11a and 11b between the optical fiber connecting means 4 and the optical fiber fixing means 3 are in an appropriate state. As described above, the relative positions of the plastic optical fibers 11a and 11b and the optical fiber fixing means 3 were adjusted, and the screws 33 of the optical fiber fixing means 3 were tightened to fix the plastic optical fibers 11a and 11b. Similarly, the plastic optical fibers 21a and 21b are inserted into the rubber-like elastic body 34, temporarily fixed to the optical fiber fixing means 3, inserted into the optical fiber connecting means 4, and the plastic optical fibers 11a and 21a are connected to 11b. 21b was connected respectively. Thereafter, the relative positions of the plastic optical fibers 21a and 21b in the optical fiber fixing means 3 on the two-fiber optical fiber cable 20 side were adjusted, and then the optical fiber fixing means 3 was firmly fixed. Finally, the position of the two-core optical fiber cable 20 in the two-core optical fiber cable fixing means 22 temporarily fixed was readjusted, and the screw 25 was tightened again. The branching work was completed by attaching the lid of the branching optical closure.
[0026]
It was 0.1 dB when the connection loss of the part branched by the branching method demonstrated above was measured using the LED light source.
[0027]
【The invention's effect】
By using the branching optical closure of the present invention, it is possible to easily branch from a multi-core plastic optical fiber cable while suppressing connection loss. Further, even when an optical fiber connection means having a weak bonding force is employed in the connection between plastic optical fibers, the influence of disturbance such as vibration and temperature change can be suppressed and stable connection performance can be maintained.
[Brief description of the drawings]
FIG. 1 is a plan view of an example of a branching optical closure according to the present invention.
FIG. 2 is an enlarged view of a fixed portion of the two-core optical fiber cable 20 in FIG.
3A is a front view of an example of the optical fiber fixing means 3, and FIG. 3B is a top view thereof.
4 is a front view of another example of the optical fiber fixing means 3. FIG.
FIG. 5 is an assembly diagram of an example of the optical fiber connecting means 4;
[Explanation of symbols]
1: optical closure for branching 2: optical fiber connection fixing means 3: optical fiber fixing means 4: optical fiber connection means 10: multi-fiber cables 11a, 11b, 21a, 21b: plastic optical fiber 12: multi-core optical fiber Cable fixing means 13: protective tube 14: grooved spacer 20: two-core optical fiber cable 22: two-core optical fiber cable fixing means 23: tension member 24: tension member tip 25, 33: screw 31: optical fiber receiver 32: Optical fiber fixing lid 34: rubber-like elastic body 35: engagement claw 36: engagement groove 41: upper member 42: lower member 43: clip 44: V groove

Claims (3)

Optical fiber connecting means for connecting plastic optical fibers;
An optical fiber fixing means for fixing the plastic optical fiber in the vicinity of the optical fiber connection means;
An optical fiber connection means fixing means comprising the optical fiber connection means and the optical fiber fixing means ,
A value obtained by dividing the linear expansion coefficient A of the optical fiber connection portion fixing means by the linear expansion coefficient B of the plastic optical fiber is 0.8 to 1.2 . Light closure. 2. The plastic optical fiber cable branching optical closure according to claim 1, wherein the optical fiber fixing means fixes the rubber-like elastic body by pressing the plastic optical fiber. The optical closure for branching a plastic optical fiber cable according to claim 1 or 2 , wherein the plastic optical fiber is a fluororesin optical fiber.

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