JPS5912410A - Optical fiber cord with plug and its manufacture - Google Patents

Abstract

PURPOSE:To prevent a decrease in optical coupling efficiency by forming a recessed part in an exposed surface of an optical fiber to a larger diameter than a small diameter hole formed in a plug, and fusing and charging a tip part of the optical fiber in the recessed part and forming a large diameter part of the optical fiber. CONSTITUTION:The recessed part 11 having the larger diameter than the small hole 4 piercing the optical fiber 7 is formed in the end surface of the plug 1, and the end part of the fiber 7 is fused and charged closely in the recessed part 11 to form the large diameter part 12, whose exposed end part is abrasive finished. Consequently, even if thermal stress operates on an optical fiber cord, the end surface of the fiber never moves back from the end surface of the plug. Therefore, there is no variation in clearance to an object of coupling, so a decrease in optical coupling efficiency is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Industrial Application Field This invention relates to an optical fiber cord with a plug, and more particularly to an optical fiber cord with a plug that improves the processing of the optical fiber at the end face of the plug, and a method for manufacturing the same. be.

(B) Prior Art The connection structure between an optical fiber and a plug in a conventional plug-equipped optical fiber cord is as shown in FIG. 1 or 2. That is, in the plug 1 shown in FIG. Bare the fiber 7 and insert the fiber 7 into the small diameter hole 40 (here, insert the end of the cord 5 still covered with the jacket 6 into the large diameter hole 3,
The gap between the outer periphery of the small diameter hole 4, the step part 2, and the large diameter hole 3 is filled with adhesive 8, and a caulked part 9 is formed on the outer periphery of the large diameter part 3. The plug 1 and the optical fiber cord 5 are integrated by tightening. Note that either filling with the adhesive 8 or caulking may be omitted.

In the plug shown in FIG. 2, the plug 1 is made of plastic, and in this case, a caulking ring 10 is fitted to the caulking portion 9 to supplement the caulking force. Note that although the illustrated case does not include filling with adhesive, filling may be performed in the same manner as in the case of FIG.

09 Problems to be Solved by the Invention In both cases, when the fiber 7 or the jacket 6 is subjected to thermal stress, the end of the fiber 7 retreats into the plug 1 or due to the expansion of the jacket 6. As a result of the relative retreat of the fiber 7, its end face may retreat into the plug 1. Therefore, there is a problem that the clearance at the coupling end with other optical fiber cords, light sources, light receivers, etc. becomes large, resulting in a decrease in optical coupling efficiency.

Furthermore, in the case where the adhesive 8 is filled as shown in FIG. 1, the adhesive 8 oozes out from the end of the fiber 7 due to swelling due to heat or water absorption, staining the end of the fiber 7. This also poses a problem in that the optical coupling efficiency decreases.

B) Means for Solving the Problems In order to solve the above problems, the present invention provides a recess with a diameter larger than the diameter of the fiber insertion hole at the end of the fiber insertion hole provided in the plug, and The fiber end is melted and filled to form the large diameter part of the optical fine.

In addition, when manufacturing an optical fiber cord having such a configuration, the fiber is made to protrude from the end face of the plug by a required length, and a heating head is pressed against the protruding part to melt the fiber end and cause the fiber to protrude from the end face of the plug. This method employs a method of filling the recesses in the container.

(E) Embodiments Hereinafter, embodiments of the present invention will be described based on the drawings from FIG. 3 onwards.

FIG. 3 shows an embodiment of the optical fiber cable with a plug according to the present invention, and the configuration other than the end of the plug 1 is the same as that in FIG. Omitted.

A recess 11 having a diameter larger than the diameter of the small diameter hole 4 through which the fiber 7 is inserted is formed on the end face of the plug 1.
The large diameter portion 12 is formed by melting the end portions of the fibers 7 and densely filling the fiber 7 into the fiber 1, and the exposed end surface thereof is polished and finished. As shown in an enlarged view in FIG.
Although the diameter of the core portion 14 is increased, the configuration in which the cladding portion 13 surrounds the core portion 14 remains unchanged. 1 Also, the cladding part 13 has a recess 11
The core portion 14 is expanded and deformed so as to be in contact with the inner wall surface of the core portion 14.
does not impede the propagation of light from the

Furthermore, the light diffusion is as shown in the dashed line 2 in Fig.
Take the optical path indicated by 0.

Therefore, a light beam having the diameter d of the core portion of the fiber 7 is diffused from the end face of the plug in a conical shape at an angle θ2. In the case of this invention, as shown by the dotted line 21, the fiber 7
A light beam having a diameter d of the end face of the core part 14 from the end of the small diameter hole 4 through which the plug is inserted is diffused in a conical shape at an angle θ1 inside the large diameter part 12 and further at an angle θ2 from the end face of the plug. Therefore, it is desirable to form the four locations 11 as shallowly as possible.

Note that the present invention can also be applied to the optical fiber cord O2 in which a fiber protection layer is closely formed on the outer layer of the cladding portion 13.

The recess 11 may have a tapered shape as shown in FIG. 5, or a V-shaped groove 15 formed in the bottom corner of the recess 11 as shown in FIG.

Note that the large diameter portion 12 is formed so as to be in close contact with the inner circumferential surface of the recess 11, and the adhesive 8 is not filled therebetween.

Next, a method for manufacturing an optical fiber cord with a plug having the above-mentioned structure, particularly a method for treating the fiber end, will be described with reference to FIGS. 7 to 9.

The method of integrating the plug 1 and the optical fiber cord 5 by filling the adhesive 8, caulking the plug 1, etc. is conventional. In the case of this invention, a recess 11 is previously provided in the end surface of the plug 1 on the side of the outer diameter hole 4, and the tip of the fiber 7 is projected from the end surface of the plug 1 by a required length so that: 13<.

The fiber 7 may be made of Branutik or glass; in each case, a heating head such as a metal plate 16 heated to a temperature sufficient to melt the fiber 7 is brought into contact with the protruding end of the plug 1. When moved in this direction, the protruding portion melts and fills the inside of the recess 11, forming the aforementioned large diameter portion 12. As a heating head, in addition to the heating metal plate 16 as described above, an ultrasonic horn 17 is used as shown in FIG. good.

In order to prevent the molten fiber 7 from being fused to the fiber contact surfaces of the heating head such as the heated metal plate 16 and the ultrasonic horn 17, a release treatment layer 18 such as fluororesin treatment is applied to those surfaces. Alternatively, the surface of the heating head described in 1 above may be mirror-finished in order to finish the fused end face of the fiber 7 flat. Alternatively, as shown in FIG. 9, the end face of the fiber 7 may be melted so as to protrude a minute amount from the end face of the plug 1, and the protruding portion may be polished.

(F) Effect As described above, the optical fiber cord with a plug according to the present invention has a large diameter portion of the optical fiber formed by melting and filling the tip of the optical fiber into the recess provided at the end of the plug. Therefore, even if thermal stress is applied to the optical fiber cord, the end face of the fiber will not retreat from the end face of the plug. Therefore, since there is no change in the clearance with the coupling target, it is possible to prevent a decrease in optical coupling efficiency.

In addition, in the case of a structure in which the plug is filled with adhesive to integrate the plug and the optical fiber cord, the large diameter portion of the fiber is in close contact with the inner wall of the recess, which prevents the adhesive from seeping out. It is also possible to prevent a decrease in optical coupling efficiency.

Further, according to the manufacturing method according to the present invention, it is possible to easily manufacture an optical fiber cord with a plug that has the above-mentioned remarkable effects.

[BRIEF DESCRIPTION OF THE DRAWINGS] FIGS. 1 and 2 are sectional views of a conventional example, FIG. 3 is a sectional view of an embodiment of the present invention, and FIG. 4 is a partially enlarged sectional view of FIG.
Figures 5 and 6 are cross-sectional views of modified examples of the plug end;
The figure is a cross-sectional view of one manufacturing step, FIG. 8 is a cross-sectional view of one step of another manufacturing method, and FIG. 9 is a cross-sectional view of the end of the plug before finishing. 1...Plug, 3...Large diameter hole, 4...Small diameter hole, 5
...Optical fiber cord, 6...Jacket, 7...
・Optical fiber, 11... recess, 12... large diameter part, 1
6... Heating metal plate, 17... Ultrasonic horn

Claims (2)

[Claims] (1) A concentric small-diameter hole and a large-diameter hole are provided in the plug, and the optical fiber exposed from the tip of the optical fiber cord is inserted into the small-diameter hole of the plug, and the jacketed part of the cord is inserted into the large-diameter hole. and an optical fiber with a plug in which the tip end face of the optical fiber is exposed to the end face of the plug. - a recess with a larger diameter than the small diameter hole is formed in the exposed surface of the optical fiber, and the tip of the optical fiber is melted and filled in the recess to form a 3° large diameter portion of the optical fiber. Features an optical fiber cord with a plug. (2) A concentric small-diameter hole and a large-diameter hole are provided in the plug, and the optical fiber cord stripped from the tip of the optical fiber cord is inserted into the small-diameter hole of the plug, and the jacketed part of the cord is inserted into the large-diameter hole. In the method for manufacturing an optical fiber cord with a plug, which integrates the plug and the optical fiber cord by inserting the optical fiber into the plug and exposing the tip end surface of the optical fiber to the end surface of the plug, a hole with a diameter larger than the small diameter hole is formed on the end surface of the plug on the side where the optical fiber is exposed. A recess is formed in advance, and the tip of the optical fiber inserted into the small diameter hole is made to pass through the recess and protrude by a required amount to the outside of the plug end face, and a heating head for melting the optical fiber is brought into contact with the tip of the protruding portion. A method for manufacturing an optical fiber cord with a plug, characterized in that a part of the optical fiber is melted and filled in the recess by moving the cord in the direction of the plug.