JPS58152211A - Method for connecting optical fiber cores - Google Patents

Abstract

PURPOSE:To obviate the generation of local stress by removing the protective clads and reinforcing layers of optical fibers, subjecting the exposed fibers to melt-sticking and a surface chemical treatment then protecting and covering the melt-stuck parts with a reinforcing layer and a protective layer of materials of respectively the same bases. CONSTITUTION:Optical fiber cores 1 are removed of protective clads by a specified length to expose strands 3; further, glass fibers 2 are exposed. The fibers 2 are connected to each other by melt-sticking. After the surface of the juncture 5 thereof is subjected to a chemical treatment, a reinforcing layer 7 is molded thereon by using dies to the same outside diameter as the outside diameter of the strands 3. A silicone resin is generally used for molding. A plastic film having the quality similar to the quality of the protective clads is used and is thermally shrunk from both sides. The flashes 11 produced by the heat shrinkage are removed with a sharp cutting blade.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for connecting optical fibers.

Optical fiber core wire is generally made of thin glass fiber with a thin reinforcing layer such as silicone resin on the surface and a protective coating of plastic such as nylon. Conventionally, in order to connect optical fibers, as shown in FIG. 1, the protective coating 4 and reinforcing layer 3 at the tips of the optical fibers are removed to expose the glass fibers, which are then heated and connected 5. This connection portion 5 is protected by molding the same material as the protective coating, such as nylon. However, since this method uses injection molding of nylon resin etc. for reinforcement, the outer diameter and internal structure of the connection part are different from other structural parts, as shown in Figure 1, resulting in bending of the core wire. The present invention has drawbacks such as the fact that the bends are not uniform and the bends are concentrated at both ends of the reinforcing part, causing local stress and causing an optical fiber breakage accident. It is an object of the present invention to provide a good connection method in which the reinforcing portion has a structure similar to that of other core wire portions, thereby eliminating the occurrence of local stress due to bending of the core wire.

The connection method of the present invention will be explained below with reference to the drawings.

As shown in Fig. 2, a certain length of the plastic protective coating is removed from the end of the Optical 7 Eyeper wire 1 to be connected to expose the optical fiber 3, and then the tip of the Optical 7 Eyer wire 3 is exposed. The reinforcing layer is removed from the glass fiber 2 to protrude, and the optical fibers are fusion spliced. After chemically treating the surface of the glass fiber fusion splice 5,
As shown in FIG. 3, the reinforcing layer 7 is molded using a mold so that it has the same outer diameter as the optical fiber strand. The molding material is the same material as the other reinforcing layers or a material of the same type, and silicone resin is generally used. Next, as shown in Fig. 5(a) and Fig. 51g1(b), a plastic film 8 made of a material having almost the same thickness as the protective coating of the optical fiber core or a material of the same type is applied to both sides of the connection part. This is thermally compressed from both sides using a mold 9 having grooves with the same diameter as the optical fiber core, thereby forming a protective coating so as to have an outer diameter comparable to that of the optical fiber core.

Immediately after thermal compression, the force at which the joints are formed is as shown in the cross section in FIG. Nylon is usually used as the glass material. In this case, a plastic tube having an outer diameter slightly larger than the optical fiber core may be used instead of the film.

The structure of the connecting portion of the optical fibers connected in this manner is the same as that of the other end of the optical fibers.

Furthermore, when the difference between the outer diameter of the optical fiber core wire and the outer diameter of the optical fiber element wire is small, that is, when the protective coating is a thin film, it is difficult to use ordinary plastic injection molding, but with the method of the present invention, a plastic flu film can be formed. Since it is thermally compressed from both sides, it can be easily molded, and the molding equipment is also simple.

As explained above in detail, the method of the present invention is based on optical fibers. After stripping the ends of the optical fibers and fusing the optical fibers, molding the joints to have the same outer diameter as the optical fibers, and then connecting the plastic films. Since both sides of the wire are heated and compressed, the connection part has the same structure as the general core wire part, and the outer diameter is almost the same, so the bending rigidity is the same for both, so stress concentration occurs due to bending of the core wire. do not have. What if the protective covering is thin? However, it has the advantage that it can be easily processed and the molding equipment is simple.

[Brief explanation of drawings]

FIG. 1 is a partial sectional view of a connection hole of an optical fiber core wire according to the conventional method, FIGS. 2, 3, and 4 are front views showing the connection process according to the method of the present invention, and FIG. 5 ia). Figure 5(b)
, FIG. 5 is a front view and a sectional view showing the length L of forming a protective coating on the connecting portion. 1: Optical fiber core wire, 2 Niglass fiber, 3: Optical fiber wire, reinforcing layer, 4: Protective coating, 5: Fusion part,
6: Mold part, 7: Reinforcement 1 mold part, 8: Film, 9: Mold, 1O: Protective coating of connection part, 11: Burr. Representative Patent Attorney Rio Tanaka Figure 1 Figure 2 Figure 3 Figure 4 ('L) (#) (C)

Claims (1)

[Claims] 1. The protective coating at the end of the optical fiber core wire to be connected is removed to expose the optical fiber wire, and the reinforcing layer at the end of the optical fiber wire is further removed to form the glass fiber. After protruding, glass fibers are fused and the surface is chemically treated, the fused portion is molded with almost the same outer diameter as the optical fiber strand and the same or similar material as the other reinforcing layers to form a reinforcing layer, Next, apply a film made of the same or similar material as the protective coating to both sides of the connection, or pass the film or tube through a tube having an inner diameter slightly larger than the outer diameter of the protective coating, and then apply the film or tube from both sides to the optical fiber core. A method for connecting an optical 7-eyeper core wire, which is characterized by forming a protective coating by thermal compression molding into almost the same external shape as the optical fiber. 2. The method for connecting optical fiber cores according to claim 1, wherein the reinforcing layer is made of silicone resin. 3. A method for connecting optical fiber cores according to claim 1 or 2, wherein the protective coating is made of nylon resin.