JPS5938714A - Reinforcing method of juncture of optical fibers - Google Patents

Abstract

PURPOSE:To improve the strength in the juncture of optical fibers and to make the juncture withstandable substantially external bending force, etc. by providing a stage for setting the juncture and a tensile body, a stage for filling a curable resin and a stage for applying a curing initiator. CONSTITUTION:This invention relates to a method of melt sticking and connecting the covering removed parts 3A, 3B of a pair of covered optical fibers 1A, 1B having said parts 3A, 3B on the connecting end side. Said method is provided with a setting stage for setting the juncture of the optical fibers and a tensile body 11 to be placed alongside said part in molding dies 4M, 4N, a resin filling stage for filling a curable resin 13 of a radical reaction type in the molding dies, and an initiator applying stage for applying an initiator 12 for curing said resin in the molding dies. Said setting stage is accomplished in precedence to the resin filling stage, and the initiator applying stage is accomplished in synchronization with either of the setting stage or the resin filling stage or before or after the same.

Description

[Detailed description of the invention] The present invention relates to a method for reinforcing optical fiber connections.

The fusion splicing method (thermal fusion splicing method) used as a means of connecting optical fibers has progressed to the point where the transmission loss at the splice can be extremely small. Technical issues remain.

First, to explain the fusion splicing method of optical fibers with reference to Fig. 1, a pair of coated optical fibers tl)A and tllB, also called optical fiber cores, are each coated with a coating layer, a single coat, etc. layers +21A, (21B), and these have coating layers (2)A, (21B) at their ends.
2) B is removed and the coating removed part [31A, +31
B is formed, and after the tip sides of the coating removal parts (3) A and (31B are cut off, both coating removal parts (31A, +
31 B ends are butted together and fusion spliced by discharge heating, laser heating, or the like.

The optical fiber connection made in this way is reinforced by coating by molding, heat-shrinkable tube, etc., but this type of reinforcement means that the coating material covering the connection When expanding and contracting from the change number, uneven lateral pressure is generated, the connection part undulates, and the connection part is not able to cope with the protrusion phenomenon that is often said to occur. Basically, the mechanical strength is insufficient. It has many built-in causes of increased transmission loss and breakage at optical fiber connections.

1. To deal with this, there is a proposal to use a tensile strength member in combination with the above-mentioned coating, and in this case, the reinforcing effect is higher than the one mentioned above, but if the cross-sectional shape of the tensile strength body is not devised, the above It is not possible to solve the problems from various angles, and the workability becomes worse.

In addition, all of the above-mentioned methods require a heat source during reinforcement, which is not only uneconomical, but also requires batteries to be kept on hand as a power source when considering work sites without power supply equipment. This increases the size of the device, and the heat treatment required for reinforcement takes several minutes, resulting in poor workability.

In view of the above-mentioned problems, the present invention improves a method for reinforcing optical fiber connections, with the main objectives of preventing an increase in transmission loss, ensuring mechanical strength, workability, and eliminating a heat source. A specific method will be explained using illustrated examples.

Fig. 2 shows an example of a pair of upper and lower molds T4+M, (41N) which can be opened and closed, and which are used in the method of the present invention. Molding space (5) M, [5] into which resin is to be injected and filled with the fiber connection part and the tensile strength body described below in a stored state.
1N is formed, and these molding spaces i51
M, (5, IN) At both ends of N there are holding parts (6
) a, (61a', i6] b, (61
b' and the optical fiber covering part +21A, +2)B holding part (71a, L71a', L71b).

+71b' (one mold (4)N above has an injection hole (8) communicating with the molding space (5)N, and a vent hole +9+ +9). , In addition, there is a mold closing means Q using embedded magnets that can be freely attracted to each other on the mold mating surfaces of the cylindrical molds (4)M and (4)N.
O)001 is provided.

The molds (41M, (4)N) may of course be made of metal, but if the inside of the mold can be viewed from the outside, they should be made of transparent synthetic resin or transparent tempered glass.

Next, to explain the various tensile strength members Uυ shown in Fig. 3, the tensile strength member qυ shown in the figure ←) has a rectangular channel shape, and its upper end and upper surface ζ are a pair of inwardly directed pieces OD+, QDl and Both of these inward pieces 0υ, , Qll
, and a slit (Il12) between them.

Furthermore, the tensile strength member qυ in the same figure (b) has a circular cylindrical shape,
On the other hand, the tensile strength body shown in FIG.
．． , IJυ411υ4... are drilled.

Of course, such a hole (1114, Qυ4, (IL
. . . may be provided in those shown in FIGS. 3(a) and 3(b), and there is no problem even if the through hole is in the shape of a long hole.

The remaining tensile strength body (see Fig. 3) is rod-shaped.

In addition, each tensile strength body circle mentioned above is mainly made of metal such as stainless steel, and in some cases, one made of FR or P is also adopted.

Figure 4 shows that the method of the present invention is applied to the molds (4) M and (4) of Figure 2.
This example shows an example in which the process is carried out using the molding die (41M, 41M,
(Since 41N has a molding space (51M, +51N) corresponding to the tensile strength body 01+ in FIG. 3(A), that tensile strength body circle is used.

In addition, the resin used in the method of the present invention, including the example shown in FIG. 4 and other examples described later, is a radical reaction type curable resin, and specifically, it may be an acrylic resin or a polyester resin, but When flexibility and adhesiveness are desired, redox resins such as polyvinylhydroquinone, hydroquinone formaldehyde resin, and dioxyphenylalanine polymer are good, and as an initiator for the curable resin, ethyl methyl ketone peroxide (MBKP), peroxide Benzoyl (B
PO) etc. are used.

In Figure 4 (a), a pair of upper and lower molds (4) M
.

(4) N are opened to each other, and the tensile strength member 0υ shown in FIG. The above-mentioned initiator α2 is supplied by an appropriate means such as injection means using an injector, brush application means, spraying method, etc. In the case of FIG. 4(a), the initiator θ
2 is applied to the inner surface of the tensile strength member (il+).

Therefore, the optical fiber connection part is set in the mold (4)M as shown in FIG. are closed together.

In this closed mold state, if either or both of the molds (4)M and (4)N are transparent, the set state of the tensile strength member aD and the optical fiber connection part can be seen from the outside, and therefore the relevant The appropriate sound of the set condition can be confirmed from the outside.

Further, the closed state at this time is maintained via the aforementioned mold closing means QO)00 using a magnet.

After the mold is closed, the molding spaces of both molds (4)M and (4)N (
5) M and (5) N are injected with a radical reaction type curable resin Q3+ from the injection hole (8).

In this way, the curable resin 0 is injected and filled into the molds (4)M and (4)N, and when the resin 03) comes into contact with or mixes with the initiator (IZ) (rough mixing is fine), the same Resin 0
3) immediately generates free radicals and cures in a chain and instantaneously.

After curing, the optical fiber connection part reinforced by this ζ is taken out from the mold +41M, (41N)
The state shown in the figure ((E) is reached.

In the above, the initiator α2 was supplied to the tensile strength member Ql) set in the set state of FIG. In such a case, the initiator O3 can be provided into the mold (4)M together with the tensile strength member 0υ.

Of course, the initiator 03 can be applied to the surface of the tensile strength body through an injector etc. even at the time shown in FIG. 4 (B) and the time shown in FIG. The initiator α2 may be provided on the inner surface of the molds (4)M and (4)N, or on the surface of the optical fiber connection portion, or may be provided on multiple locations of the molds (4)M and (4)N.
The time can be arbitrarily selected, such as at the time shown in Figure (c) or earlier.

In addition, the resin filling step (see Fig. 4) is completed without supplying the initiator Oz, and then the initiator O is supplied through the injector.
2 into the molds (4)M and (4)N, or the initiator can be injected in synchronization with the filling process.For synchronous injection, a plurality of injection holes are provided in the mold.

Next, the embodiments shown in Figs. 5 and 6 will be explained. Fig. 5 is an embodiment that adopts the tensile strength body shown in Fig. 3 (b), and Fig. 6 shows the tensile strength of Fig. 3 (b). In both of these embodiments, the optical fiber connection portion is reinforced in the same manner as in the case of FIG. 4.

In the case of Fig. 5, which adopts the tensile strength member uD shown in Fig. 3 (b),
By providing at least one through hole or notch in the peripheral wall of the tensile strength body, the resin can also enter into the tensile strength body, and even when the tensile strength body 0υ shown in FIG. It will look like Figure 5.

In addition, when the shape structure of the tensile strength member 11) changes in the above, each holding part f6) a% t6) a', (
Glb % (61b', (71a, (71a',
The shapes of (71b, (71b') will also change as necessary.

Next, the embodiment shown in FIG. 7 will be explained. In this embodiment, both ends of the tensile strength body circle are also covered with resin, so that the mold (4) M, as shown in FIG.
(4)N has molding spaces (5)M, and small molding spaces (51M', (51N) adjacent to the ends of (5)N).
' is formed.

In the case of Fig. 7 (a), the optical fiber connection part is also reinforced by any of the means described above, and the thus reinforced connection part becomes as shown in Fig. 7 (b). , the method of the present invention is a method for reinforcing an optical fiber splicing portion in which a pair of coated optical fibers having a sheath removed portion on the splicing end side are fusion spliced with the tips of the sheath removed portions abutted against each other. A setting process in which the fiber connection part and a tensile strength member attached to the connection part are set in the mold, a resin filling process in which the mold is filled with a radical reaction type curable resin, and a start for curing the resin. The above-mentioned setting step is performed prior to the resin filling step, and the initiator providing step is performed in conjunction with either the setting step or the resin filling step. It is characterized by being performed synchronously or one after the other.

Therefore, in the optical fiber connection reinforced by the method of the present invention, the removed portion is not only covered with resin, but also the connection and the tensile strength body are integrated using the resin as a binder. The strength of the connecting portion is greatly improved depending on the tensile strength member, and even if an external force such as bending is applied to the optical fiber connecting portion, it can withstand it without causing breakage or the like.

Of course, the above-mentioned tensile strength member almost completely prevents the resin from expanding and contracting due to temperature changes, so there is no problem of undulations or uneven lateral pressure at the optical fiber connection, and therefore there is no problem of increased transmission loss. Not only that, but the problem of breakage is also solved here.

Furthermore, the above-mentioned tensile strength member suppresses the extrusion phenomenon by preventing the aforementioned expansion and contraction, so there are almost no problems with strength, ensuring long-term reliability of the optical fiber connection. can.

Moreover, in order to be able to effectively reinforce the optical fiber connection as described above, the radical reaction type curable resin is chained and instantaneously cured by its initiator, so the curing in this case is conventional: 3 What used to take ~5 minutes now takes less than 30 seconds, and the mold clamping pressure during molding is O~5K.
As q/crA can be reduced by two digits compared to the conventional example, the workability is greatly improved and can be easily implemented on site.

Of course, there is no need for a heat source for curing the resin, and there is almost no need for mold clamping, so there is no need to use expensive molds from the viewpoint of strength, and the economic effectiveness of the equipment that performs this is therefore increased. , it is also easy to carry out on-site work in that it can omit incidental equipment such as a power supply.

Since no particular strength is required, the mold can be made of transparent synthetic resin, such as acrylic, polycarbonate, silicone, etc. In such cases, it is more convenient to be able to check the set state inside the mold and the hardened state of the resin. get well.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of an optical fiber connection part, Fig. 2 (a) and (b) are longitudinal sectional front views and vertical sectional side views showing an example of a mold used in the method of the invention, and Fig. 3 is an illustration of the method of the invention. Perspective views of various tensile strength members used in the method 1 of the present invention, FIGS.
Explanatory diagrams showing examples in order of process, Figures 5, 6, and 7
Figures (a) and (b) are explanatory diagrams showing other embodiments of the method of the present invention. (1) A, (IjB...Coated optical fiber (+2)
A, +2) B...-covering part +3) A, +3
1 B...Coating removal part (4)M, +4)N・
...Molding mold (5)M, (5)M', (5)N,
(51N'...Molding space aυ...Tensile strength body αri...Initiator 0...Curing resin 18 Figure 3 Figure 4 (AI) Naka, Ibaraki Prefecture Ibaraki Telecommunications Research Institute, Nippon Telegraph and Telephone Public Corporation, 162 Shirane, Oaza, Shirakata, Tokai-mura, Gun Applicant: Nippon Telegraph and Telephone Public Corporation 65-

Claims (3)

[Claims] (1) In the method for reinforcing an optical fiber joint, in which a pair of coated optical fibers having a sheath removed portion on the splicing end side are fusion spliced with the tips of the sheath removed portions abutted against each other, the optical fiber splice is A setting step in which the connecting portion and a tensile strength member to be attached to the connecting portion are set in a mold, a resin filling step in which a radical reaction type curable resin is filled into the mold, and an initiator for curing the resin is added. The setting process is performed before the resin filling process, and the initiator feeding process is performed at the same time or before or after either the cent process or the resin filling process. 1. A method for reinforcing an optical fiber joint, characterized in that the method comprises: (2) The method for reinforcing an optical fiber connection portion according to claim 1, wherein the mold is transparent. (3) The method for reinforcing an optical fiber connection portion according to claim 1, in which the tensile strength member has a groove shape, a cylindrical shape, or a restrained shape.