JPS5918404Y2 - Structure of terminal assembly for multi-core optical fiber connection - Google Patents

Description

[Detailed description of the invention] The invention provides an optical fiber cable communication system.
The present invention relates to an optical fiber terminal assembly structure used in an easily detachable optical connector for optically connecting multi-core optical fibers or a multi-core optical fiber cable to other optical devices.

In general, under the condition that the end face of an optical fiber cable has a smooth butting surface to prevent incident loss of light, the optical axes of the cores of the optical fibers on the connecting side and the connected side will be misaligned. is one of the biggest factors causing optical connection loss.

For this reason, for example, in the case of a single-core optical fiber cable, the terminal parts whose outer periphery is machined into a cylinder with high precision based on the core part are inserted into a sleeve having a guide hole approximately equal to the outside diameter of the cylinder, and then mutually connected to each other. The core portions of the optical fibers are often used by matching them together.

In this way, in the case of a single-core optical fiber cable, it is relatively easy to match the core parts, but in the case of a multi-core optical fiber cable, the core parts of all optical fibers can be matched by simply butting them together. To achieve this, it is necessary to control and align their mutual positions with high precision.

Generally, an optical fiber cable includes a core portion and a cladding portion outside the core portion, and is called an optical fiber wire, and a core portion and a cladding portion outside the core portion, which are referred to as an optical fiber core wire. refers to a cable made of optical fiber.

Furthermore, a multi-core optical fiber cable is a cable made by collecting a plurality of optical fibers.

Further, the optical fiber wire has a substantially perfect circular shape, and has a structure in which the core portion is located approximately at the center of the cladding portion.

Therefore, the alignment structure of the strands at the end of a multi-core optical fiber cable often utilizes the above-mentioned outer diameter dimensional accuracy characteristics of the fiber strands. A highly accurate V-shaped groove is machined on the outer circumferential surface of a round bar, and the grooves are divided and arranged according to the number of optical fibers at highly accurate pitch intervals.

Insert the optical fiber wires one by one into this V-shaped groove and fix them with adhesive etc. to maintain the pitch accuracy between each core part. The core parts are inserted into a cylindrical guide member having a cylindrical guide member and abutted against each other, and at the same time all the core parts are brought into alignment.

However, the outer diameter of the optical fiber is 150 μm or 20 μm.
It is a thin wire of about 0 μm, and the size of the V-shaped groove into which this thin wire is inserted is extremely small. In order to connect all the cores in a consistent manner, the shape accuracy of the V-shaped groove, the pitch of the V-shaped groove, etc. must be adjusted to a μm-order processing precision. required.

Naturally, machining such a V-shaped groove with high precision requires special machining machines, machining tools, and the like.

The object of the present invention is to eliminate these drawbacks and at the same time provide a structure for a terminal assembly for connecting multi-core optical fibers that can be easily manufactured, especially using ordinary machine tools.

The present invention will be explained in detail below with reference to the drawings.

FIG. 1 is an end view showing a state in which an optical fiber wire is fitted and fixed in a conventional V-shaped groove of a cylindrical member 2.

In the figure, an optical fiber wire 1 is fitted and fixed into a V-shaped groove of a cylindrical member 2 whose outer peripheral surface is machined with a V-shaped groove.

However, in order to align the core portions of a plurality of optical fibers 1 at the same time by simply butting the V-shaped cylindrical members 2 against each other, it is necessary to Grooves are made using special machine tools and careful machining by skilled workers, and in fact, it is almost impossible to do with ordinary machine tools.

In particular, it is necessary to suppress the amount of deviation in the pitch interval of the optical fiber strands 1 to a few micrometers or less; if the deviation is more than that, the splice loss will be extremely aggravated.

FIG. 2 is an end view of one embodiment of the present invention.

The terminal structure of the present invention is such that the outer circumferential surface of the central member 3 having highly accurate roundness is in contact with the inner circumferential surface of the cylindrical member 4 whose inner hole has highly accurate circularity, and the adjacent Fiber wire 1
The outer periphery of the central member 3 and the cylindrical member 4 are in contact with each other.
The optical fiber wire 1 is arranged between the inner periphery of the fiber and the inner circumference of the fiber.

The outer periphery of the central member 3 and the inner periphery of the cylindrical member 4 described above literally need to have highly accurate roundness. Each of the above-mentioned members can be easily manufactured using common machine tools.

Note that in order to closely arrange the optical fiber 1 between the center member 3 and the cylindrical member 4, which have approximately the same distance as the outer diameter of the optical fiber 1, Dimensions and conditions must be met.

That is, when the diameter of the optical fiber of the multi-core optical fiber cable to be used is a and the number of optical fibers is n, the outer diameter D1 of the central member 3 is, and the inner diameter D2 of the cylindrical member is D2-D1+2a. Seek.

However, when this structure is used, the size of the connecting terminal assembly is determined by the optical fiber diameter a and the number n of optical fibers, and each time a and n change, the central member and the cylindrical member are must be designed.

However, by arranging a round bar 5 having approximately the same outer diameter as the optical fiber strand 1 in place of the optical fiber strand 1, it is possible to avoid changing the exterior dimensions of the terminal assembly even if only n changes. be able to.

An example thereof is shown in FIG. FIG. 3 is an end view when 14 optical fiber strands 1 and seven round bars 5 having the same dimensions as the outer diameter of the strands 1 are used in a 21-fiber terminal assembly.

Furthermore, according to this terminal structure, it is effective only when there are three or more optical fibers 1, but by using the method shown in Fig. 3, it can be applied to single-core and double-core cords. be.

FIG. 4 shows a perspective view of a connection example of an optical connector using the terminal structure of the present invention.

In the figure, the end assemblies 6 of multi-core optical fiber cables formed in the structure of the present invention are aligned with each other in a guide cylinder 7 having an inner diameter approximately equal to the outer diameter of the cylindrical member 4 using the outer peripheral surface of the cylindrical member 4 as a guide. 8 and a guide pin 9 that precisely matches this slit, the core portions of each optical fiber strand of the multi-core optical fiber cable can be easily matched by inserting from both sides of the guide cylinder 7.

As described above, the present invention enables terminal assembly for connecting multi-core optical fiber cables by utilizing the outer diameter dimensional accuracy of the optical fiber itself, without using special machine tools. Since it is possible to form a connection structure in which the parts match butt each other, the cost is lower than that of conventional terminal assemblies.

[BRIEF DESCRIPTION OF THE DRAWINGS] FIG. 1 is an end view of a terminal assembly using a conventional V-shaped groove, FIG. 2 is an end view of an embodiment of the terminal assembly of the present invention, and FIG. 2 is an end view of an application example of FIG. 2, and FIG. 4 is a perspective view of an example of connecting multi-core optical fiber cables using the terminal assembly of the present invention.

Claims (1)

[Scope of claim for utility model registration] The terminal parts of three or more optical fibers having approximately the same outer diameter,
In the structure of the terminal assembly in which pairs of multi-core optical fiber terminal assemblies aligned between the outer periphery of the central member and the inner periphery of the cylindrical member are butted and connected to each other, the multi-core optical fiber terminal assemblies are A rod having the same outer diameter as the optical fiber is included between the member and the cylindrical member, and when the sum of the numbers of the optical fiber and the rod is n and the outer diameter is a, the The outer diameter D1 of the central member and the inner diameter D of the cylindrical member
2 is selected to have a value determined by the following formula.