JP3035839B2 - Curing method of adhesive for optical connector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for curing an adhesive for fixing an optical fiber and an optical connector ferrule at the time of assembling an optical connector for connecting an optical fiber.

[0002]

2. Description of the Related Art Currently, in order to provide broadband services such as CATV and high-definition television, construction of a subscriber optical line network connecting a telephone station and a subscriber is being actively promoted. In order to construct this subscriber optical line network, an optical fiber cable and an optical fiber connection technology are important.

[0003] This optical fiber cable uses an optical fiber tape in which a plurality of optical fiber wires are collectively covered, and furthermore, the development of a multi-core optical connector for connecting these simultaneously makes it possible to connect them collectively. Work efficiency has improved dramatically.

FIG. 3 is a cross-sectional view of the coated optical fiber, and FIG. 4 is a cross-sectional view of a four-core optical fiber tape in which the four optical fibers shown in FIG.

In FIGS. 3 and 4, reference numeral 8 denotes an optical fiber;
Is an optical fiber coating, and 10 is a collective coating.

[0006] There are fusion splicing and connector splicing methods for connecting optical fibers.

[0007] The fusion splicing is a method of connecting optical fibers by electric discharge, and the connector connection is such that an optical fiber is inserted and fixed in a connector plug made with high precision, and these two plugs are connected by using fitting pins or the like. It is a method of connecting by aligning the axes.

FIG. 5 is a perspective view of a connection example of a multi-core optical connector. 5, 1 is an optical connector ferrule, 2 is a connector window, 3 is a V-groove, 4 is a fiber hole, 5 is a fitting pin hole, 7 is an optical fiber tape, 11 is a fitting pin, and 12 is a connector clip. , V-grooves are provided in accordance with the number of optical fibers in the optical fiber tape.

As shown in FIG. 5, a plurality of optical fibers can be connected collectively by abutting the optical connector ferrules 1 in the direction of the arrow via the fitting pins 11 and fastening them with the connector clips 12.

To assemble the optical connector, the optical fiber coating is removed, the optical fiber is inserted into the optical connector ferrule 1, and
There are four steps of bonding and edge polishing. In the bonding step among these, there are filling of the adhesive and curing of the adhesive, which is the most time-consuming step in assembling the optical connector. This uses a thermosetting adhesive as the adhesive, and it takes 1
This is because it takes about 0 minutes.

In the bonding step, the optical fiber 8 from which the optical fiber coating 9 and the collective coating 10 have been removed is inserted into the optical connector ferrule 1 and the adhesive is filled into the connector window 2 and the fiber hole 4 and then heated for about 10 minutes. Let it cure. Filling the adhesive into the fiber hole is performed by pushing the optical fiber filled with the adhesive into the connector window and the coating removed.
It is performed by a method of putting an adhesive into a gap between the inner wall of the fiber hole and the optical fiber.

[0012]

However, in the above-mentioned bonding step, the adhesive hardens due to heat curing.
It takes about a minute and there is a problem that workability is poor. This is because a thermosetting adhesive is used in consideration of the adhesive strength and reliability between the optical fiber and the optical connector ferrule. This is because there is no mold adhesive. That is,
For the type that cures in a short time, the adhesive strength between the optical fiber and the optical connector ferrule is weak, or the adhesive strength decreases when a long-term high-temperature and high-humidity test is performed assuming the environment where the optical connector is used. This is because there is a problem in reliability such as an increase in light loss. Therefore, even if time is sacrificed, a thermosetting adhesive having high adhesive strength and high reliability is used.

On the other hand, as an adhesive other than the thermosetting adhesive, there is an ultraviolet curing adhesive. This UV-curable adhesive is
It is cured in a short time by irradiating ultraviolet rays. However, when assembling an optical connector using the ultraviolet curing type, there is a disadvantage that the adhesive filled in the fiber hole does not cure and the optical fiber in that portion is not fixed. That is, the optical connector ferrule is made of black plastic in consideration of weather resistance and the like for use outdoors, and the optical fiber outer diameter and the fiber hole inner diameter are 1 to 2 μm.
This is because the ultraviolet light does not hit the adhesive that has entered the gap portion, and that portion is not cured. The presence of the uncured portion significantly deteriorates the transmission characteristics and reliability of the optical connector.
Therefore, no ultraviolet curable adhesive was used for the above reasons.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method of curing an adhesive, which solves the above two problems and has a fast curing time and can securely fix an optical fiber in a fiber hole of an optical connector ferrule. It is in.

[0015]

According to the present invention, an ultraviolet curing type curing by irradiation with ultraviolet rays is used as an adhesive, and the adhesive is previously applied to a portion of an optical fiber inserted into a fiber hole of an optical connector ferrule. The optical fiber is inserted into the fiber hole of the optical connector ferrule and cured before application and irradiation of ultraviolet light to start curing of the adhesive.

[0016]

According to the method for curing an adhesive for an optical connector of the present invention, an ultraviolet-curable adhesive which cures in a very short time by irradiating ultraviolet rays is used, and is inserted into a fiber hole of an optical connector ferrule of an optical fiber. The adhesive is applied to the part to be cured, and the curing is started by irradiating ultraviolet light for a short time, so if the optical fiber is inserted into the fiber hole before it is completely cured, the adhesive hardens in the fiber hole. The optical fiber can be fixed in the fiber hole.

[0017]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 is a bonding process diagram in assembling an optical connector. The operations are performed in the order of (1), (2), (3) and (4).

In FIG. 1, 1 is an optical connector ferrule, 2 is a connector window, 3 is a V-groove, 4 is a fiber hole,
Is a fitting pin hole, 6 is an adhesive, 7 is an optical fiber tape, 8
Is an optical fiber.

FIG. 2 is a sectional view taken along the line AA 'of FIG. 1 (2). There is a gap of about 1 to 2 .mu.m between the outer diameter of the optical fiber 8 and the inner diameter of the fiber hole 4. Is filled with the adhesive 6, and the optical fiber 8 is fixed.

(1) Insert the tip of the optical fiber from which the coating has been removed up to the center of the V-groove (the center of the connector window). Next, a small amount of an ultraviolet curing adhesive 6 is dropped on the connector window 2 and applied to the tip of the optical fiber. After the application, the connector window 2 is preliminarily irradiated with ultraviolet rays for several seconds (hereinafter referred to as pre-irradiation).

(2) After pre-irradiation with ultraviolet rays, the optical fiber from which the coating has been removed is pushed in to the end before the adhesive starts curing. As a result, the space between the fiber hole 4 and the optical fiber 8 is filled with the ultraviolet curable adhesive so as to be pressed by the optical fiber 8. FIG. 2 shows the state at this time, and the ultraviolet curable adhesive enters a slight gap between the outer diameter of the optical fiber and the inner diameter of the fiber hole. The ultraviolet-curable adhesive used here starts a chemical reaction even with short-time ultraviolet irradiation, and then has a characteristic that the reaction proceeds even if the ultraviolet light does not shine, so even if ultraviolet light does not directly hit the fiber hole. The chemical reaction proceeds and the adhesive cures.

(3) Next, the connector window 2 is filled with the adhesive and the coating is applied to the end face of the optical connector ferrule, and the connector window section 2 and the end face of the optical connector ferrule are again irradiated with ultraviolet rays to cure and cure. Fix it.

(4) After being completely cured, the optical fiber 8 protruding from the end face of the optical connector ferrule is cut at the boundary with the adhesive to complete the bonding step.

After the above-described bonding step, the end face of the optical connector ferrule is polished.

The results of experiments using the method of the present invention will be described. First, the experiment was conducted by using a UV-curable adhesive and performing no pre-irradiation. At that time, the adhesive in the connector window was cured and fixed in an average of 2 minutes. However, when this sample was cut along the line AA 'in FIG. 1 (2), the uncured ultraviolet curable adhesive oozed out of the fiber hole. This is because, as described above, the ultraviolet ray does not reach the gap between the optical fiber and the fiber hole, and is not cured. Further, although the connector window was irradiated with ultraviolet rays for 10 minutes, the ultraviolet curable adhesive oozed out of the fiber hole and did not cure.

On the other hand, the pre-irradiation was carried out for 5 seconds by the pre-irradiation method of the present invention, and the same experiment as above was conducted. Hardened and fixed. Also, as in the previous experiment, A
When cut between -A ', the UV-curable adhesive that entered the fiber hole was cured and no bleeding of the adhesive was observed. It was confirmed that it could be cured and fixed.

In general, the reaction speed of an ultraviolet curable adhesive is increased by heat, and therefore, when the method of the present invention is performed while heating, the curing / fixing time can be shortened.

[0029]

As described above in detail, according to the present invention, when an ultraviolet-curable adhesive is used, it is cured in an extremely short time by irradiating ultraviolet rays, and the optical fiber is connected to the fiber of the optical connector ferrule. By performing pre-irradiation before inserting into the hole, the optical fiber can be securely fixed to the fiber hole of the optical connector ferrule, so that the characteristics, reliability, and workability of the connector are significantly improved. Has a significant effect.

Further, by performing the heating step in parallel, an effect that the working time can be further reduced can be expected.

[Brief description of the drawings]

FIG. 1 is a bonding process diagram in assembling an optical connector.

FIG. 2 is a sectional view taken along the line AA ′ of FIG. 1 (2).

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

FIG. 4 is a sectional view of a four-core optical fiber tape.

FIG. 5 is a perspective view of a connection example of an optical connector.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Optical connector ferrule 2 Connector window part 3 V groove 4 Fiber hole 5 Fitting pin hole 6 Adhesive 7 Optical fiber tape 8 Optical fiber 9 Optical fiber coating 10 Batch coating 11 Fitting pin 12 Connector clip

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-63-49711 (JP, A) JP-A 57-112306 (JP, U) JP-A 1-67610 (JP, U) JP-A 61- 198906 (JP, U) Jpn. Sho 62-4770 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) G02B 6/36 C09J 5/00 JICST file (JOIS)

Claims (1)

(57) [Claims] 1. A method of curing an adhesive for adhesively fixing an optical fiber in a fiber hole of an optical connector ferrule, comprising applying an ultraviolet curing adhesive to a portion of the optical fiber to be inserted into the fiber hole. Before irradiating ultraviolet rays and the adhesive starts to be cured, the optical fiber is inserted into the fiber hole to be cured, and the optical fiber is fixed in the fiber hole of the optical connector ferrule. How to cure the adhesive for optical connectors.