JPH06331517A - Method for screening mechanical strength of optical fiber connecting part - Google Patents

Abstract

PURPOSE:To objectively, uniformly, accurately and efficiently conduct strength inspection of an end of a glass core of an optical fiber over the entire exposed core length after its cover is removed. CONSTITUTION:A method for screening the mechanical strength of an optical fiber connecting part comprises the steps of fixing the end of a glass core (g) of an optical fiber (f) after its cover is removed to a jig 10, then applying a predetermined tensile force to the end of the fiber (f) to conduct a strength test, removing the end of the core (g) fixed to the jig 10, and polishing it for connecting.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for screening the mechanical strength of an optical fiber connecting terminal before connection, and the result of the inspection of the mechanical strength of the connecting terminal is objective and unified. It is possible to remarkably improve the reliability of, and to reduce the connection failure due to insufficient mechanical strength after connection of the connection portion as much as possible.

[0002]

2. Description of the Related Art An optical fiber has a cross-sectional structure shown in FIG. 3 and comprises a core glass 1 and a clad glass layer 2 surrounding it.
And the clad glass layer is covered with a coating layer 3 (UV resin, carbon, metal, etc.) called a primary coat, and each layer has a concentric structure. As a method for sequentially connecting the optical fibers, there are roughly a fusion splicing method in which the ends of the optical fibers are melted to be connected, and a connector connection method in which the ends of the optical fibers are butted against each other using a connector connected to the ends of the optical fibers. However, the coating layer 3 at the end of the optical fiber must be removed by either method. On the other hand, the optical fiber having the above-mentioned cross-sectional structure has high mechanical strength against pulling, bending, etc., but the glass core consisting of the core glass 1 and the clad glass layer 2 surrounding it has extremely fine damage (0, 1 μm) on its surface. It is a well-known characteristic that the mechanical strength thereof is extremely reduced (a fraction) and becomes unusable when subjected to the following. When the surface of the glass core is scratched when the coating layer 3 is removed to connect the end of the optical fiber, even if the scratch is extremely fine, the connection in the state of being connected due to the scratch It is unavoidable that the mechanical strength of the part is significantly reduced. After the coating layer 3 of the optical fiber f is removed in order to ensure a certain level or more of mechanical strength of the connected portion after the connection, a test (screening) of the mechanical strength of the glass core of the terminal portion is performed. In this inspection, the exposed end of the glass core g having a constant length and exposed by the optical fiber f is laterally pushed with a fingertip to bend it, and in that state, the end is rotated by 360 ° to obtain a predetermined size in the direction of 360 °. The bending force is applied (see FIG. 4). If the terminal portion of the glass core g exposed by this inspection is damaged to a certain extent or more, it breaks at the damaged portion, so that the damaged portion can be found in advance before connection and the damaged portion can be removed in advance. When the terminal does not break in this inspection, it is passed and the terminal is used for connection. Since this inspection method is performed by relying on the intuition of a skilled worker, the inspection work itself is not efficient, and the inspection method is not uniform, the objectivity of the inspection results is poor, and In reality, the required bending cannot be applied to the tip portion of the glass core g, and thus the reliability of the inspection result is poor, and therefore the occurrence of connection failure due to insufficient mechanical strength of the connection portion is sufficient. There is still the problem that it cannot be reduced.

[0003]

SUMMARY OF THE INVENTION The present invention has as its object to solve the above-mentioned problems of the prior art. Therefore, the strength inspection of the end of the glass core after removal of the coating of the optical fiber is exposed. Objective, uniform, accurate,
And the task is to be able to do it efficiently.

[0004]

[Means for Solving the Problems] The measures taken to solve the above problems are constituted by the following elements (a) and (b). (A) Fix the tip of the glass core after removing the coating of the optical fiber to the jig, and then apply a predetermined tensile force to the end part of the optical fiber to perform a strength test. After removing the fixed tip, use it for connection,

[0005]

[Operation] When a simple tensile force is applied to the optical fiber with the tip of the glass core exposed by removing the coating fixed to the jig, the glass core is evenly tensioned all around its circumference, and Since the magnitude of this simple tension can be adjusted mechanically and accurately, the inspection can be performed uniformly, objectively, quantitatively and accurately. The tip fixed to the jig is not given a predetermined tension, and it is highly possible that the surface is damaged due to contact with the jig, but this part is cut off and the cut surface is ground before connection. Therefore, the portion whose strength is not confirmed by the above inspection is never used for connection.

[0006]

Practical Example First, an example in which the above-described inspection is simultaneously performed on a plurality of optical fibers will be described with reference to FIG.
The jig 10 includes a base 11 and a holding plate 12, and the base 11
The upper surface of is coated with hard plastic,
A hard rubber layer 13 is laminated on the lower surface (pressing surface) of the pressing plate 12. The base 11 is supported by a rail L fixed to the upper surface of the work table T so as to be movable in the direction of arrow YY. A pulling device 30 provided on the work table T is attached to the base 11 of the jig 10. This pulling device may be any one as long as it has a tension adjusting function and a tension displaying function. Many optical fibers f
The coating of the end is removed to expose the glass core g by a predetermined length, and the glass core g is arranged substantially parallel to the upper surface of the base 11, and the holding plate 12 is appropriately tightened with bolts, nuts, or the like. The tip of the glass core g is fixed to the base 11 by tightening with a mechanism. The glass core g is formed by the hard plastic layer on the upper surface of the base 11 and the hard rubber layer 13 on the lower surface of the pressing plate 12.
Since the tip of the glass core is gripped, the tip of the glass core is softly and strongly gripped by the jig. After fixing the tip of the glass core g to the jig 10, the main body of the optical fiber f is fixed to the jig 1.
It is fixed to the clamp 20 near 0. The clamp 20 may be of any type as long as it can firmly fix the main body portions of all the optical fibers f in a parallel state. In this example, a support base 21 having a flat upper surface, like the jig 10, is used. A clamp device is used to tighten the holding plate 22 with an appropriate tightening mechanism such as bolts and nuts. The tension applied to the optical fiber varies depending on the use condition, the use environment, etc. of the optical fiber, but if the optical fiber f is a standard cladding diameter of 125 μm and a silica glass fiber, and the test tension is 1 kg, in this example, Since there are four optical fibers, the pulling force of the pulling device 30 is set to 4 kg. The jig 10 is pulled for a predetermined time (for example, 3 seconds) while operating the pulling device to check the pulling force F by the display mechanism. At this time, a simple pulling force is evenly applied to each optical fiber f, and a fiber having a damaged surface is broken.
With respect to the optical fiber f that has not been broken, the tip of the glass core held by the jig 10 is cut off, and the cut surface is polished for connection. When used for connector connection, jig 1
Before fixing to 0, pass the optical fiber through a ferrule coated with an adhesive in advance, make the glass core project from the ferrule, fix the tip of the glass core to a jig and apply tension, and after screening It is only necessary to cut the tip of the material that has not been broken, fix it to the ferrule as it is, and then polish the end face of the glass core. The above embodiment is an example in which the tip of the glass core is fixed to the jig by the clamp mechanism. However, a plate-shaped replacement part is detachably fixed to the upper surface of the base 11 of the jig, and the replacement part The tip of the glass core may be fixed to the upper surface by using a so-called instant adhesive. In this case, the tip fixed to the jig is cut off from the glass core g and left on the replacement part. Therefore, when there is no room to bond a new glass core to the upper surface of the replacement part, the replacement part is replaced. do it. Furthermore, in the case of screening the optical fibers one by one, as shown in FIG.
It is advisable to adhere to No. 0 with the instant adhesive agent 41 and apply a predetermined tension while confirming the tension by an appropriate tension means. In this case, a person may pull it through the tension measuring means.

[0007]

[Advantages] Since the invention which solves the above-mentioned problems of the present invention is not known, the above-mentioned problems are novel. Therefore,
It is an effect peculiar to the present invention itself that the above-mentioned new problems are solved and the problems of the above-mentioned prior art are solved. In particular, when the method of the present invention is used, the glass core can be passed through a ferrule and fixed to this, so that post-screening can be performed. Since the deterioration of the mechanical strength of the connection part due to the above is also screened, and the part accommodated in the exposed ferrule of the glass core is also screened, the reliability of the strength of the connection part is higher. This effect is applicable not only to the connector connection but also to all connection methods in which a part of the exposed glass core is housed in the housing and the strength of this part cannot be confirmed outside.

[Brief description of drawings]

FIG. 1 is a perspective view of a first embodiment of the present invention.

FIG. 2 is a perspective view of a second embodiment.

FIG. 3 is a sectional view of an optical fiber.

FIG. 4 is an explanatory diagram of a conventional screening method.

[Explanation of symbols]

 10 ... Jig 20 ... Clamping device 30 ... Tensioning device f ... Optical fiber g ... Glass core

Claims (1)

[Claims] 1. A tip of a glass core after the coating of the optical fiber is fixed to a jig, and then a predetermined tensile force is applied to the end portion of the optical fiber to perform a strength test, and the glass core is fixed to the jig. A mechanical strength screening method for an optical fiber splicing part, in which after the removed tip is removed, it is polished and used for splicing.