JPS6157913A - Assembling method of connector for optical fiber - Google Patents

Abstract

PURPOSE:To expand and deform a hollow pipe, to press an optical fiber in two columnar styli and to fix it in the center of an outer cylinder of a ferrule by putting two columnar styli and one hollow pipe, i.e. three in the outer cylinder of the ferrule, and inserting an insertion stylus which does not deform into the hollow hole of the hollow pipe made of a material which deforms. CONSTITUTION:The optical fiber cable having the clad removed outside the base end of the core is inserted fixedly into the core. Further, the optical fiber covered with a protection film is run through the through hole 22 of the ferrule incorporated in the tip of the core 1, the protection film of the tip is peeled off to expose the internal optical fiber 5, and the optical fiber 5 having the protection film and clad coating removed is inserted among three styli 24 put in the outer cylinder 35 of the ferrule 20. Then, an insertion stylus 41 having a larger diameter than the hollow hole 24b is inserted into the hollow hole 24b of the hollow pipe 24 finally to cause the hollow pipe 24c to expand and deform. The optical fiber is clamped with the three styli 24, and consequently the optical fiber 4 is fixed in the center of the external cylinder 35.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method of assembling optical fiber connectors used for interconnecting optical fibers.

Conventional technology Optical fibers consist of a core through which light is transmitted and a cladding that covers it, but the core diameter is extremely small, less than 100 μm, so it is currently difficult to align the centers of the optical fibers and connect them. be. Particularly in the case of optical fiber connectors that are used in a removable manner, the machining accuracy of the connector directly affects the connection loss of the optical fiber. For this reason, the most important point when using a three-way optical fiber connector is to align and fix the center of the optical fiber with the center position of the connector body. To explain a conventional method of assembling an optical fiber connector to overcome this problem, for example, Fig. 1 shows a 1tli side view of a conventional optical fiber connector.
Attach the stripped outer sheath 3 of the optical fiber cable 2 covered with the protective film and outer sheath, fix the outer sheath 3 to the core 1 with the outer sheath fixing 4, and cover it with the protective film inside the outer sheath 3. The optical fiber 5 with its protective film removed is inserted into the ceramic pipe 8 placed in the through hole 7 of the ferrule 6 built into the tip of the core L, and then bonded. 9 is a frame for holding a mating connector (not shown), 10 is a coupling nut used for connection with the mating connector, and 11 is a protective film extending from the base end of the core 1 to the outside. This is a hood that is placed over the end of an optical fiber cable 2 having a cover. This assembly sequence consists of an optical fiber covered with a protective film and an outer jacket.
Insert the hood 11, jacket holder 4, and core 1 sequentially from the end of the eyebar cable 2, peel off the jacket 3, let the optical fiber covered with a protective film protrude from the core 1, and remove the protective film at the tip. Δ11 to expose the optical fiber 5, apply adhesive to it, insert it into the ceramic pipe 8, apply adhesive to the outer periphery of the ceramic pipe 8, insert the ferrule 6 therein, and insert the base of the ferrule 6. The end is inserted into the core 1.

Problems to be Solved by the Invention However, in the conventional method described above, in order to facilitate the insertion of the optical fiber 5 and to account for variations in the outer diameter of the optical fiber 5, the inner diameter of the ceramic pipe 8 is set to several tens of meters larger than the outer diameter of the optical fiber. Therefore, there is a possibility that the eccentricity of the optical fiber with respect to the ceramic pipe 8 reaches several micrometers, and there is a limit to the accuracy of alignment, and alignment with a high degree of stacking cannot be expected.

In addition, the coating layer of the optical fiber is usually fixed to the core 1 from the distal end to the proximal end by means of adhesive or caulking, but the ceramic pipe 8 and the optical fiber 5 from which the coating has been removed are fixed. If this is insufficient, a shrinkage force will be generated in the coating layer due to heat cycles, etc., and as a result, a phenomenon will occur in which the optical fibers within the coating layer will protrude.

Means for Solving the Problems The present invention uses a ferrule consisting of three mutually circumscribing needles that grip an optical fiber and an outer cylinder having an inner diameter circumscribing the three needles, and of the three needles in the ferrule, two One is a cylindrical needle that does not deform, and the other is a hollow tube made of an easily deformable material, and an insertion needle with an outer diameter larger than the inner diameter of the hollow hole is inserted into a hollow hole provided in the center of the hollow tube. By inserting the ferrule, the hollow tube expands and deforms, thereby forcing the optical fiber between the two cylindrical needles, thereby fixing the optical fiber at the center of the outer cylinder of the ferrule, thereby solving the above problem.

EXAMPLES The present invention will be described below with reference to examples shown in the drawings.

The basic structure of the ferrule installed at the tip of an optical fiber connector is shown in Figure 2. In this figure, 2
0 is a precisely finished metal ferrule, 21a
21b is a protrusion, and 21C is a housing part for housing and fixing an optical fiber covered with a protective film. A through hole 22 having an inner diameter slightly larger than the outer diameter including the protective film of the optical fiber is provided along the axis of the ferrule 20 from the end surface, and the optical fiber is inserted and fixed therein together with the protective film. Ru. The other end of the through hole 22 continues from the end surface of the fitting portion 21a to a fixing hole 23 having a roughly large diameter that is coaxially bored along the axis of the ferrule 20. Three needles 24 having the same length as the depth of the fixing hole 23 are installed in the fixing hole 23.

FIGS. 3 and 4 show an optical fiber 5 and a needle 24 according to an embodiment.
FIG. Here, two of the three needles 24 (11i+ are cylindrical needles 243 that do not deform), and these two cylindrical needles 248 are connected to the fitting part 21.
An outer cylinder 35 that forms the outer periphery of the fixing hole 23 drilled in a.
When inserted so as to be inscribed in
If the optical fiber 5 from which the protective film and outer covering have been removed is placed in the valley formed by the outer surface of each of the cylindrical needles 243,
It has a shape set so that the axis of the ferrule 20 and the center of the optical fiber 5 coincide. The other needle 24 has the same external shape as the cylindrical needle 242 before deformation, but has a slightly smaller diameter, and the inside thereof is a hollow tube 24c in the shape of a pipe with a hollow hole 24b provided therein. The material is an easily deformable and elastic material, such as rubber.

Therefore, when the hollow tube 24c is put into the outer tube 35 together with the other two cylindrical needles 24a, there is a large gap between the three needles 24, and the optical fiber 5 can be easily inserted into the gap. It becomes possible.

Describing the method for assembling the optical fiber connector here, the optical fiber cable 2 whose jacket has been peeled off on the outer side of the proximal end of the core 1 is inserted and fixed into the core 1 in the same manner as in the conventional example described above, and is further covered with a protective film. The optical fiber is passed through the through hole 22 of the ferrule 20 installed at the tip of the core 1 (installed in the same position as the ferrule 6 shown in FIG. 1).
The protective film at the tip of the optical fiber 5 is removed by machining 11 to expose the internal optical fiber 5, and the protective film and outer covering are removed.
The three needles 24 housed in the outer cylinder 35 of the ferrule 20
(Insert between two cylindrical needles 24a and one hollow tube 24C). Finally, an insertion needle 41 having a diameter larger than the diameter of the hollow hole 24b is inserted into the hollow hole 24b of the hollow tube 24c,
By inserting the insertion needle 41, the hollow tube 24C is expanded and deformed, and as shown in FIG.
The optical fiber 5 is thereby fixed at the center of the outer cylinder 35. A preferred example of the insertion needle 41 here is one that is made of the same material as the cylindrical needle 24a and does not deform, as shown in FIG. 5, has the same overall length as the needle 24, and has an insertion tip. It has a slightly smaller diameter than the diameter of the hollow hole 24b, and tapers from its tip, and the root and body have a larger diameter than the hollow hole 24b, and when the hollow tube 24C is expanded and deformed by inserting the insertion needle 41, the hollow tube The diameter of the cylindrical needle 24c is such that it is deformed to the same diameter as the diameter of the cylindrical needle 24a.

Effects of the Invention As detailed above, in the present invention, a total of three needles, two cylindrical needles and one hollow tube, are housed in the outer cylinder of the ferrule, and an optical fiber can be easily inserted between the needles. After that, an undeformable insertion needle is inserted into the hollow hole of a hollow tube made of an easily deformable material, and the hollow tube expands and deforms to press the optical fiber against the two cylindrical needles, and the optical fiber is inserted into the outer tube. By increasing the space between the three needles during insertion, it becomes easier to insert the optical fiber, and it also accommodates variations in the outer diameter of the optical fiber.
Since the fiber is sufficiently fixed, it is possible to prevent the optical fiber from protruding even when subjected to heat cycles.

Furthermore, since no adhesive is required as in the conventional example, there is no need for waiting time for curing, and there is no need for adhesive to adhere to the end face of the optical fiber, so there is no need for polishing of the end face. Therefore, the time required for assembly is significantly reduced.

[Brief explanation of drawings]

Figure 1 is a sectional view of a conventional optical fiber connector, Figure 2 is a sectional view of the basic structure of a ferrule, Figures 3 and 4.
The figures are explanatory diagrams showing the relationship between the optical fiber and the needle before and after assembly, and FIG. 5 is an illustrative diagram of the insertion needle.

Claims (1)

[Claims] (1) When fixing an optical fiber to the ferrule of an optical fiber connector, three mutually circumscribing needles are used to hold the optical fiber at the center of an outer cylinder having an inner diameter circumscribing the needles, but two needles are deformed. The other needle is made of an easily deformable and elastic material, and the needle is a hollow tube with a hollow hole inside. When inserting the removed optical fiber into the ferrule, make sure that there is enough space between the three needles in the outer tube to insert the optical fiber, and after inserting the optical fiber with the coating removed into the gap, By passing an insertion needle with a diameter larger than the diameter of the hollow tube through the hollow hole of the hollow tube, the hollow tube is expanded and deformed, thereby pressing the optical fiber against the two cylindrical needles, and inserting the optical fiber into the center of the outer cylinder of the ferrule. A method for assembling an optical fiber connector, characterized by fixing the connector.