JP3752134B2 - Mechanical splice - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a mechanical splice that can easily connect optical fibers.
[0002]
[Prior art]
Currently, in the field of communications, optical fibers capable of high-speed and large-capacity transmission have become the mainstream of transmission lines, and most medium- and long-distance trunk lines have already replaced optical fiber cables from conventional metal cables. Furthermore, efforts are being made at a rapid pace to realize an optical subscriber line transmission system that is going to use optical fiber for the lines to homes several years later.
[0003]
In order to realize this optical subscriber line transmission system, it is necessary to connect multi-core optical fibers having a large number of optical fiber cores, and fusion splicing has conventionally been performed as a method of connecting these optical fibers. I came.
[0004]
Fusion splicing is a highly reliable process because the optical fiber strands exposed by removing the coating from the optical fiber core are butted together and the butted surfaces of the optical fiber strands are melted and connected. It took time to reinforce, and the problem was that the device was expensive and required a power source.
[0005]
Therefore, as shown in Japanese Patent Laid-Open No. 9-318836, a mechanical splice has been proposed and is being developed, in which an optical fiber core wire is axially aligned with a V-groove or the like to be fixed and connected easily. Yes.
[0006]
This mechanical splice is expected to reduce the cost of connection due to the simplicity of the structure and connection method.
[0007]
FIG. 8 shows a conventional mechanical splice.
[0008]
As shown in FIG. 8, a conventional mechanical splice 51 includes a V-groove substrate 55 formed with a V-groove for positioning optical fibers, and an optical fiber core from above to a V-groove. A holding substrate 56 for holding, and a clamp spring 57 for holding and fixing the V-groove substrate 55 and the holding substrate 56 from above and below are provided.
[0009]
When an optical fiber is connected using this mechanical splice 51, as shown in FIGS. 9 (a) and 9 (b), a wedge insertion groove formed between the V-groove substrate 55 and the holding substrate 56 is used. A wedge 59 is inserted into 58 to widen the gap between the V-groove substrate 55 and the holding substrate 56, and the gap between the V-groove substrate 55 and the holding substrate 56 is shown in FIGS. 10 (a) and 10 (b). As shown in FIGS. 11 (a) and 11 (b), the optical fiber 52 is inserted into the V-groove from both ends and the optical fiber strands 53 at the tip of the optical fiber 52 are butted together. 59, the optical fiber strand 53 is positioned and gripped in the V groove 54 by the restoring force of the clamp spring 57.
[0010]
The mechanical splice 51 shown in FIG. 8 is a single-core mechanical splice 51 for connecting single-core optical fibers having one optical fiber core wire. In addition to this, as shown in FIG. There is also a four-fiber mechanical splice 61 in which four V-grooves 62 are formed.
[0011]
In this four-fiber mechanical splice 61, as shown in FIG. 12B, four rows of V-grooves 62 are formed, and each core wire 63 of the optical fiber to be butt-connected is inserted into the V-groove 62, respectively. It is like that.
[0012]
[Problems to be solved by the invention]
On the other hand, in main trunk lines of recent transmission systems, cables containing 8-fiber optical fiber tapes are used due to an increase in the amount of information, and an 8-fiber mechanical splice has become necessary.
[0013]
For this reason, the inventors made a prototype of an 8-fiber mechanical splice 65 having a structure similar to that of the 4-fiber mechanical splice 61 shown in FIG. 12 and having 8 rows of V-grooves 64 as shown in FIG. did.
[0014]
However, in this 8-fiber mechanical splice 65, since the resin is used for the V-groove substrate 67 and the holding substrate 68 in order to reduce the cost, the rigidity is not high. For this reason, the distribution of the force in the width direction by the clamp spring 69 of the V-groove substrate 67 and the holding substrate 68 becomes weaker as it moves outward with the convex portion 71 of the clamp spring 69 as the center. Although the core wire 72a positioned within the width can be securely gripped, no force is applied to the outer core wire 72b, the grip becomes insufficient, and the optical fiber strands are butted when subjected to a temperature cycle. There is a problem that a gap is generated in the portion and the connection loss is increased, or the connection loss is increased due to the storage after the connection.
[0015]
As a method for preventing this, it is conceivable to increase the width of the convex portion 71. In this case, the distance between the upper and lower convex portions 71 and the total thickness of the V-groove substrate 67 and the pressing substrate 68 are completely the same. Otherwise, it is known that the convex portion 71 of the clamp spring 69 is in a single-contact state with respect to the V-groove substrate 67 and the holding substrate 68, and on the contrary, variation in the gripping force of the optical fiber occurs. For this reason, the manufacturing accuracy of the mechanical splice 65 has to be increased, leading to an increase in cost.
[0016]
Accordingly, an object of the present invention is to provide a mechanical splice that solves the above-described problems and is capable of reliably grasping the entire core wire at low cost even with a multi-core optical fiber.
[0017]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, the invention of claim 1 is characterized in that a V-groove substrate in which V-grooves that support and align and align opposing optical fibers are formed, and the V-groove is overlapped with the V-groove substrate. In a mechanical splice having a holding substrate for holding the inserted optical fiber, and a clamp spring for holding the optical fiber by sandwiching the V-groove substrate and the holding substrate, the holding substrate is formed of an elastic body, By forming a recess extending in the optical axis direction centering on the position where the optical fibers are abutted with each other on the V-groove substrate or the pressing substrate , the V-groove substrate and the pressing substrate are removed with the clamp spring removed. DOO does not abut, match-the pressing board by pinching of the clamp spring is toward the butted portion bent in the optical fiber of the optical fiber In which it was to hold the position.
[0018]
According to a second aspect of the present invention, the holding substrate is divided into an optical fiber holding part facing the position where the optical fibers are abutted with each other, and an optical fiber core holding part other than the optical fiber holding part. The recesses are formed by protrusions provided at the four corners of the optical fiber holding part, and the optical fiber holding part is connected to the optical fiber in order to maintain rigidity in a direction perpendicular to the optical axis. The contacting part is thicker.
[0019]
According to a third aspect of the present invention, the holding substrate is divided into an optical fiber holding part facing the position where the optical fibers are abutted with each other and an optical fiber core holding part other than the optical fiber holding element holding part. The recesses are formed by protrusions formed at the four corners in the vicinity of the butted portion of the V-groove substrate, and the optical fiber holding portion is in order to maintain rigidity in a direction perpendicular to the optical axis. The portion in contact with the optical fiber is thick.
[0020]
According to the above configuration, when the V-groove substrate and the pressing substrate are clamped by the clamp spring, the non-contact portion of at least one of the V-groove substrate and the pressing substrate bends in the optical axis direction and toward the optical fiber. Hold the optical fiber with. At this time, if the force of the clamp spring is approximately the center of the non-contact portion, even if there is a slight positional shift, the position where the deflection is the largest is the central portion in the optical axis direction of the non-contact portion (concave portion). And the center in the width direction, which is the butting position of the optical fiber.
[0021]
In addition, the non-contact portion of the holding substrate is bent in the optical axis direction and toward the optical fiber, whereby the rigidity in the width direction of the optical fiber gripping surface located at the center of the non-contact portion in the optical axis direction (secondary section) Moment) becomes higher. Therefore, the distribution of force by the clamp spring in the width direction at the center of the non-contact portion in the optical axis direction is substantially uniform, and even in the case where there are a large number of optical fiber cores, the optical fiber is uniformly and reliably extended to the outside in the width direction. Can be gripped. Furthermore, since the manufacturing accuracy may be the same as the conventional one, the cost increase can be suppressed.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
Next, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.
[0023]
FIG. 4 shows a perspective view of the mechanical splice according to the present invention, and FIG. 3 shows a cross-sectional view in the width direction of the optical fiber butting position of this mechanical splice.
[0024]
As shown in FIG. 4, the mechanical splice 1 is a connector for inserting and butt-connecting optical fibers from both sides facing each other, for supporting and aligning the optical fibers. A bar-shaped V-groove substrate 4 in which a V-groove 3 having a substantially V-shaped cross section is formed, and a presser formed with a flat surface for pressing the optical fiber that is superimposed on the V-groove substrate 4 and inserted into the V-groove 3 A substrate 5 and a clamp spring 6 having a U-shaped cross section for sandwiching the optical fiber by sandwiching the V-groove substrate 4 and the pressing substrate 5 are provided.
[0025]
As shown in FIG. 3, the clamp spring 6 is formed with convex portions 9 extending on the V groove substrate 4 and the holding substrate 5 side on the upper and lower sides thereof. The convex portion 9 is formed by extruding the clamp spring 6 in a circular shape at a predetermined interval in the longitudinal direction of the optical fiber.
[0026]
In addition, the V grooves 3 are formed in parallel with the same number (eight in this case) of the optical fiber cores 2 to be abutted along the longitudinal direction of the V groove substrate 4.
[0027]
The center part in the longitudinal direction of the V-groove 3 is formed to have substantially the same depth and width, and the optical fiber cores 2 inserted from both sides of the V-groove substrate 4 are aligned and abutted. ing.
[0028]
On the other hand, both ends in the longitudinal direction of the V-shaped groove 3 are formed at positions lower than the central portion, and a connecting portion with the central portion is formed in a tapered shape and connected.
[0029]
Further, a wedge insertion groove 8 for inserting a wedge (not shown) is formed at the open end of the overlapping portion of the V-groove substrate 4 and the holding substrate 5, and the wedge insertion groove 8 has a wedge. Is inserted to repel the spring force of the clamp spring 6 to open the V-groove substrate 4 and the pressing substrate 5 to form a gap.
[0030]
In addition, as shown in FIG. 2, the V-groove substrate 4 and the holding substrate 5 of the present invention, when the clamp spring is removed, when the V-groove substrate 4 and the holding substrate 5 are overlapped, The V-groove substrate 4 and the pressing substrate 5 that extend in the optical axis direction with the butting position as the center have a portion where the V-groove substrate 4 and the pressing substrate 5 do not contact each other (hereinafter referred to as a recess 13), and the non-contacting portion of the V-groove 3 When the optical fiber strand 7 is brought into contact with the optical fiber strand 7, the optical fiber strand 7 is formed in a depth shape that does not contact the holding substrate 5.
[0031]
Specifically, the holding substrate 5 is formed of an elastic resin, and a portion on which an optical fiber gripping surface 10 for pressing the exposed optical fiber 7 is formed by removing the coating of the optical fiber core wire 2. (Hereinafter, referred to as “optical fiber holding portion”) 5a and a portion (hereinafter, referred to as “optical fiber holding portion”) 5b that holds the core wire 2 that is not covered and removed. And is integrally supported by a clamp spring.
[0032]
Further, the V-groove substrate 4 is also formed of a resin having elasticity, and the longitudinal center portion 11 is lower than the longitudinal end portions 12 on the surface in contact with the optical fiber strand holding portion 5a. A recess 13 is formed by providing such a step 4a. And the length of this recessed part 13 in the optical axis direction is formed slightly shorter than the length of the optical fiber strand holding part 5a so that the both ends 5e of the optical fiber holding part 5a can be supported. Further, the steps 4a are formed substantially evenly in the width direction.
[0033]
Next, the operation will be described with reference to FIGS.
[0034]
When the optical fibers are butt-connected using the mechanical splice according to the present invention, as shown in FIG. 4, the wedge is inserted into the wedge insertion groove 8 to insert the wedge between the holding substrate 5 and the V-groove substrate 4. The optical fiber subjected to the end treatment is inserted into the formed gap from both ends of the V-groove substrate 4, and the optical fiber strand is inserted in the V-groove 3 at the substantially central portion in the longitudinal direction of the V-groove substrate 4 as shown in FIG. After matching 7 together, remove the wedge.
[0035]
At this time, the optical fiber element holding part 5a is pushed out by the convex part 9 at the center part in the longitudinal direction of the clamp spring 6, and the non-contact part (optical fiber holding surface 10) of the V-groove substrate 4 and the optical fiber element holding part 5a. ) Bends toward the butt of the optical fiber.
[0036]
Since the force of the clamp spring is approximately the center of the non-contact portion, the position where the deflection is the largest even if there is a slight displacement is the center portion in the optical axis direction of the non-contact portion and the center portion in the width direction. It is the butting position of the optical fiber.
[0037]
Therefore, the rigidity in the width direction of the optical fiber gripping surface 10 that is the center in the optical axis direction of the non-contact portion and is the butting position of the optical fiber is increased.
[0038]
As a result, the distribution of force by the clamp spring 6 in the width direction at the central portion of the non-contact portion in the optical axis direction becomes substantially uniform, and the optical fiber strand 7 is pressed in this state. 4 and the pressing substrate 5 can be held and fixed and connected uniformly.
[0039]
Therefore, even if it receives a temperature cycle, a clearance gap does not arise in the butt | matching part of an optical fiber, and the increase in connection loss can be reduced.
[0040]
Specifically, 20 mechanical splices 1 for 8 cores were manufactured, and a temperature cycle test of 10 cycles was performed with -40 to 70 ° C./6h as one cycle. The increase in the loss of the mechanical splice 65 was 0.3 dB or more, whereas in the mechanical splice 1 of the present invention, a good result that the increase in loss was 0.1 dB or less was obtained.
[0041]
Furthermore, according to the present invention, the V-groove substrate 4 and the pressing substrate 5 can be manufactured with the same inexpensive resin as the conventional one, and the manufacturing accuracy may be the same as the conventional one, so that an increase in cost can be prevented.
[0042]
Next, another embodiment of the present invention will be described.
[0043]
FIG. 5 is a perspective view of an optical fiber element holding part of a mechanical splice showing another embodiment of the present invention, and FIG. 6 is a longitudinal sectional view of the main part of the mechanical splice using the optical fiber element holding part of FIG. It is.
[0044]
As shown in FIG. 5, this optical fiber strand holding portion 22a has projections 23 formed at the four corners of a rectangular plate-shaped main body, and these projections 23 and V-groove substrates come into contact with each other at four locations. A non-contact portion (a recess 28 having an optical fiber gripping surface 27) is formed at the center of the pressing portion 22a. In addition, in order to maintain the rigidity in the direction perpendicular to the optical axis, the distance between the four positions where the protrusions 23 are formed is longer in the optical axis direction than in the width direction. The wire pressing portion 22a is formed in a taper shape from both longitudinal ends to the center portion, and the portion in contact with the optical fiber is thick.
[0045]
As shown in FIG. 6, the mechanical splice provided with the optical fiber strand holding portion 22a has a flat surface facing the optical fiber strand holding portion 22a of the V-groove substrate 24.
[0046]
Also in the mechanical splice 21, the optical fiber strand holding portion 22 a is configured such that the non-contact portion between the V-groove substrate 24 and the optical fiber strand holding portion 22 a is an optical axis by the convex portion 26 at the center in the longitudinal direction of the clamp spring 25. The rigidity in the width direction of the optical fiber gripping surface 27 located at the center in the optical axis direction of the non-contact portion is increased.
[0047]
Therefore, similarly to the mechanical splice 1 shown in FIG. 1, the distribution of the force by the clamp spring 25 in the width direction at the central portion in the optical axis direction of the non-contact portion becomes substantially uniform, and in this state, the optical fiber 7 Therefore, the optical fiber strand 7 can be uniformly held and fixed and connected by the V-groove substrate 24 and the optical fiber strand pressing portion 22a.
[0048]
Further, as a modification of the mechanical splice 21, as shown in FIG. 7, protrusions 23 formed at the four corners of the optical fiber strand holding portion 22a shown in FIG. good.
[0049]
That is, the V-groove substrate 24 is provided with projections 23 at the four corners in the vicinity of the optical fiber butting portions 28 to form the recesses 28, and the interval between the four locations where the projections 23 are provided is equal to the optical fiber strand holding portion. In order to maintain the rigidity in the direction perpendicular to the optical axis 22a, the interval in the optical axis direction is longer than the interval in the width direction.
[0050]
On the other hand, the optical fiber strand holding portion 22a is formed in a rectangular plate-like main body with a tapered groove that guides the optical fiber strand to the butting position from both longitudinal end portions to the central portion.
[0051]
Also in this mechanical splice, the same effect as the mechanical splice 1 shown in FIG. 1 can be expected.
[0052]
In the present embodiment, the cross-sectional shape of the V groove 3 that supports and aligns the optical fiber core wire 2 is formed in a V shape. However, the present invention is not limited to this, and is not limited to this. It may be.
[0053]
Furthermore, in this embodiment, eight rows of V grooves 3 are formed, but the present invention is not limited to this. That is, when connecting optical fibers having a larger number of cores, V grooves corresponding to the number of the cores may be provided.
[0054]
【The invention's effect】
In short, according to the present invention, the force distribution by the clamp spring in the width direction at the center in the optical axis direction of the non-contact portion becomes substantially uniform. Can be securely gripped, and is excellent in reliability and handling.
[0055]
Furthermore, the present invention can produce a V-groove substrate, a holding substrate, and the like with an inexpensive material, and exhibits the excellent effect of preventing an increase in cost because the manufacturing accuracy may be the same as the conventional one.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of an essential part of a mechanical splice showing an embodiment of the present invention.
FIG. 2 is a longitudinal sectional view of a mechanical splice showing an embodiment of the present invention.
FIG. 3 is a cross-sectional view in the width direction of a mechanical splice showing one embodiment of the present invention.
FIG. 4 is a perspective view of a mechanical splice showing an embodiment of the present invention.
FIG. 5 is a perspective view of an optical fiber holding portion of a mechanical splice showing another embodiment of the present invention.
FIG. 6 is a cross-sectional view of the main part in the longitudinal direction of a mechanical splice showing another embodiment of the present invention.
7 is a cross-sectional view of the main part in the longitudinal direction showing a modification of the mechanical splice of FIG. 6. FIG.
FIG. 8 is a perspective view of a conventional single-core mechanical splice.
FIG. 9 is a diagram for explaining an optical fiber connection method using a mechanical splice.
FIG. 10 is a diagram for explaining an optical fiber connection method using a mechanical splice.
FIG. 11 is a diagram for explaining an optical fiber connecting method using a mechanical splice.
FIG. 12 is a perspective view showing a structure of a four-core mechanical splice.
FIG. 13 is a cross-sectional view in the width direction of a conventional mechanical splice.
[Explanation of symbols]
2 Optical fiber core (optical fiber)
4 V-groove substrate 5a Optical fiber strand holding part (holding substrate)
5b Optical fiber core wire holding part (holding substrate)
6 Clamp spring 13 Recess

Claims (3)

A V-groove substrate formed with a V-groove that faces and supports and aligns the facing optical fibers, a holding substrate that holds the optical fiber superimposed on the V-groove substrate and inserted into the V-groove, and the V-groove in mechanical splice and a clamp spring for gripping the substrate and presser sandwiching the substrate said optical fiber, the presser substrate so as to form an elastic body, the optical fiber to each other in the V-groove substrate or the holding substrate By forming a recess extending in the optical axis direction with the abutting position as the center, the V-groove substrate and the pressing substrate are not in contact with each other in a state where the clamp spring is removed, and the clamp spring holds the above wherein the holding substrate is to hold the butt position of the optical fiber bends toward the butt portion of the optical fiber Crab callus price.   The holding substrate is divided into an optical fiber holding part facing the position where the optical fibers are abutted with each other, and an optical fiber core holding part other than the optical fiber holding part, and the recess is the optical fiber holding part. Formed by protrusions provided at the four corners of the fiber strand holding portion, and the optical fiber strand holding portion has a thickened portion in contact with the optical fiber in order to maintain rigidity in a direction perpendicular to the optical axis. The mechanical splice according to claim 1.   The holding substrate is divided into an optical fiber holding part facing the position where the optical fibers are abutted with each other, and an optical fiber core holding part other than the optical fiber holding part, and the concave part is the V Formed by protrusions formed at the four corners in the vicinity of the butted portion of the groove substrate, and the optical fiber strand holding portion is thick at the portion in contact with the optical fiber in order to maintain rigidity in a direction perpendicular to the optical axis. The mechanical splice according to claim 1.

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