JPH0690346B2 - Optical fiber connector manufacturing method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for manufacturing an optical fiber connector which is integrally attached to an end portion of an optical fiber and connects the end portions of the optical fiber to each other. .

[Conventional technology]

In recent years, in information communication systems, optical fibers have been widely used as communication cables.Since such optical fibers are laid over a long distance, they can be connected to each other or to other devices. It is also used. And to connect such an optical fiber,
A connector 1 as shown in FIG. 4 is used. That is, the connector 1 is composed of a main body 3 having a concave portion 2 provided on the upper surface and a lid portion 4 which can be fitted into the concave portion 2 of the main body 3, and an engaging protrusion 5 is provided on a side wall of the concave portion 2. A plurality of engaging claws 7 are provided on the lower surface of the lid portion 4, which can hold and fix the optical fiber 6 with the engaging protrusions 5.
Are projected. Then, the tip end side of the main body 3 is formed into a square tubular connection portion 8, and a cylindrical projection 9 is formed from the inside thereof.
Is protruding. The central hole 9a of the cylindrical protrusion 9 is composed of a core and a cladding portion (a core portion having a high refractive index of light is surrounded by a cladding portion having a low refractive index) which is a central portion of the optical fiber 6. The size is set so that the fiber core portion 6a of the fiber can be inserted, and the hole 10 (on the one end side of the body 3 on the one end side of the body 3 from which one end of the body 3 on the extension line of the center hole 9a can be inserted) The hole is hidden and invisible)
Are provided coaxially with the center hole 9a. Therefore, the coating layer 6b on one end side of the optical fiber 6 is removed, the one end side is inserted into the hole 10 of the main body 3 from the other end side, and the core and the cladding portion 6a at the tip end thereof are made into the center of the cylindrical projection 9. By fitting the lid portion 4 into the concave portion 2 of the main body 3 while being inserted into the hole 9a, the engaging claw 7 of the lid portion 4 and the engaging protrusion 5 of the main body 3 cover the coating layer 6b of the optical fiber 6. Can be clamped and fixed. As a result, in this state, by connecting the connecting portion 8 of the main body 3 to another device or the like, the core and the cladding portion 6a can be connected to the device or the like.

However, since the connector 1 is attached to the optical fiber 6 by sandwiching and fixing the covering layer 6b of the optical fiber 6 with the engaging claw 7 provided on the lid 4 and the engaging protrusion 5 of the main body 3, When a pulling force is applied and exceeds the frictional locking force between the coating layer 6b and the engaging claws 7 and the engaging protrusions 5,
There is a problem that the optical fiber 6 easily comes off. There is also a problem that the number of parts increases and the connector 1 itself becomes large. Therefore, we have
As a connector for an optical fiber which can solve the above problems, a device in which a connector is integrally formed on the end side of the optical fiber has been devised and an application has already been filed (Japanese Patent Application No. 63-20152). In other words, this optical fiber connector is
As shown in FIG. 5, the end portion side of the optical fiber 6 is arranged in the molding die 11, and in that state, the resin liquid for molding the connector is injected from the injection port 12 into the space portion 13 in the molding die 11. Then, the connector is integrally formed on the end side of the optical fiber 6.

[Problems to be solved by the invention]

However, in the above optical fiber connector, when injecting the resin liquid for molding the connector into the molding die 11,
The fluid pressure causes the core and the cladding portion 6a to bend and become eccentric. As a result, there is a problem that the optical transmission loss becomes large (as a result of the test, the optical transmission loss in this case was 9.2 dB). For this reason, as shown in FIG. 6, the injection port 12a is provided at a portion corresponding to the base side of the optical fiber 6 so that the resin liquid can be injected in a state parallel to the optical fiber 6 to mold the connector. Ivy. As a result, the optical transmission loss of the obtained connector was reduced to 4.5 dB, but further improvement is desired.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a method of manufacturing an optical fiber connector capable of preventing the occurrence of optical transmission loss due to eccentricity.

[Means for solving problems]

In order to achieve the above-mentioned object, a method for producing a connector for optical fibers according to the present invention is to prepare an optical fiber provided with a fiber core wire and a coating layer on the outer periphery thereof, and remove the coating layer at the end portion of the optical fiber. , The end portion side of the optical fiber is linearly arranged in the molding die with the tip of the end portion facing the end portion side of the molding die for forming the connector. A method for producing an optical fiber connector in which a connector molding resin material is press-fitted into the molding die from an inlet to integrally mold the connector on the end side of the optical fiber, wherein the molding die is a peripheral wall surface of a molding chamber. , An injection port is formed in the part facing each other across the optical fiber, facing the optical fiber, and at the exit part of the injection port, the molding resin material collides with itself and changes its direction. Longitudinally along connexion fluent baffle portion of Ivor adopt a configuration that is provided.

[Action]

That is, according to the method of manufacturing the connector for optical fiber of the present invention, the optical fiber is linearly arranged in the molding die, and the baffle plate portion is provided at the outlet of the injection port of the molding die. By injecting the molding resin material from the injection port provided so as to face each other so as to be in contact with each other, the molding resin material is pressed into the molding die to integrally form the connector on the outer periphery of the optical fiber. . Therefore, the molding resin material injected into the molding die collides with the baffle plate and its momentum is killed, and it penetrates into the inner side of the forming chamber in a symmetrical fluid pressure state across the optical fiber. Will come to work. As a result, the flow pressure of the molding resin material is evenly applied to the outer circumference of the optical fiber, and the optical pressure does not cause the optical fiber to be eccentric in one direction. Therefore, it is possible to prevent optical transmission loss due to eccentricity.

Next, the present invention will be described in detail based on examples.

〔Example〕

FIG. 1 shows a connector obtained according to one embodiment of the present invention. In the figure, 15 is a core and a cladding 15a
(Fiber core wire) is an optical fiber formed by coating with a coating layer 15b. A methacrylic resin core having a diameter of 980 μm is coated with a fluorinated resin cladding having a thickness of 20 μm. The cladding 15a is covered with a polyethylene coating layer 15b. In this optical fiber 15, the coating layer 15b on one end side is removed, and the core and the cladding portion 15a are exposed in the removal trace. Reference numeral 16 denotes a connector body made of polyacetal, which is integrally formed in a state of covering the boundary portion between the coating layer 15b remaining side of the optical fiber 15 and the core / clad portion 15a exposed side. This connector body 16 has a connection part 17 with a thin tip.
And a ring-shaped groove portion 18 is provided along the circumference on the inner peripheral side of the rear end portion. A concave portion 17a is provided on the tip side of the connecting portion 17, and a cylindrical projection portion 19 coaxially incorporating the core and the cladding portion 15a projects from the center of the bottom surface of the concave portion 17a. Reference numeral 20 designates a rubber boot portion for connector protection which is detachably attached to the outer periphery of the optical fiber 15 on the remaining side of the coating layer 15b from the rear end side of the connector main body 16. Recess 21 to fit
The ring-shaped protruding portion 22 provided on the bottom surface of the connector is fitted in the groove portion 18 of the connector body 16 and attached.

Such a connector can be manufactured as follows. That is, first, the coating layer on one end side of the optical fiber 15
15b is removed to expose the core and cladding portion 15a. Next, a molding die 23 as shown in FIG.
a temperature equal to or lower than the softening temperature of a (the softening temperature of the coating layer 15b is the core,
(The temperature is higher than the softening temperature of the cladding portion 15a), and the boundary portion between the remaining portion of the coating layer 15b of the optical fiber 15 and the core and the exposed portion of the cladding portion 15a is linearly extended in the mold 23. Arrange. Then, in that state, the molding die
In the molding space 23a of 23, two softening temperature +
The temperature is set to 150 ℃ or below, and the melt flow rate is 5g /
A liquid polyacetal of min or more is injected so as to be orthogonal to the optical fiber 15, and a molding space is formed on the outer periphery of the above boundary part.
A connector body 16 having the same shape as 23a is formed. Incidentally, a ring-shaped baffle plate 25 is formed on the inner peripheral surface of the molding die 23 at a portion corresponding to the root side of the optical fiber 15 in the molding die 23.
The optical fiber fixing hole 23b of the optical fiber 23 is provided so as to be flush with the optical fiber fixing hole 23b and covers the root side of the optical fiber 15.
Therefore, at the time of the above formation, the liquid polyacetal injected from the two vertically symmetrical injection ports 24 collides with the baffle plate 25 and loses its momentum, so that the molding space 23 is formed.
It is formed on the connector body 16 by advancing to the back side of a. At that time, since liquid polyacetal is injected from the two upper and lower injection ports 24, the fluid pressure is evenly applied to the upper side and the lower side of the optical fiber 15, and the linearity of the optical fiber 15 is properly maintained. It Further, when the liquid polyacetal is solidified, shrinkage (molding shrinkage ratio of 2.5 or more) occurs, so that the optical fiber 15 is firmly fixed to the connector body 16. Next, the core projecting from the cylindrical projection 19 of the connector body 16 and the cladding portion 15a are cut off, and the preformed rubber boot portion 20 is fitted to obtain a connector as shown in FIG. To be
By connecting the connecting portion 17 of this connector to another connector or equipment, the tip of the core / clad portion 15a can be connected to the core / clad of another optical fiber. During molding of the connector, the temperature of the molding die 23 rises due to the heat of the polyacetal, but this is cooled by water cooling or the like to be prepared for the next use, whereby the softening temperature of the optical fiber 15 is constantly maintained below the softening temperature. It

As a result of a test using the connector thus obtained, the optical transmission loss of the optical fiber 15 was 2.7 dB. In addition, as a result of repeatedly attaching and detaching the connector to and from the equipment, almost no output fluctuation was observed. Further, a pull-out test was performed by pulling the connector and the optical fiber 15 in opposite directions. That is, first, with a load of a little over 4kg, keep it for 1 minute, and then add a load of 7k
Increased to g and held for 1 minute. Next, when the load was increased, the optical fiber 15 started to grow at 13 kg, but the optical fiber 15 did not come off from the connector. Since the connector of the conventional example shown in FIG. 4 is detached from the optical fiber 6 by applying a load of 7.5 kg, it can be said that the connector of the present invention has sufficient pull-out strength to withstand use. If the above connector is made of nylon (molding shrinkage 0.3-0.8%), the pull-out force is 8.7k.
The pull-out force was 13.0 kg when it was composed of g and polypropylene (molding shrinkage ratio 1.0 to 1.5%).

In this way, this connector is arranged linearly in the molding die 23 in a state where the optical fiber 15 is covered at the base side with the ring-shaped baffle plate 25, and the optical fiber 15 is vertically symmetrically provided so as to sandwich the optical fiber 15. By injecting the molding resin material toward the baffle plate 25 from the two inlets 24, the optical fiber 15
Is integrally formed at the end of the. Therefore, at the time of molding the connector, the flow pressure of the molding resin material is evenly applied to the optical fiber 15, and the optical fiber 15 is prevented from being eccentric in one direction due to the flow pressure. As a result, it becomes possible to prevent optical transmission loss due to eccentricity. In addition, this connector
Temperature is set below the softening temperature of the core of the optical fiber 15 and the cladding portion 15a, and the temperature is above the softening temperature +15.
It is manufactured by injecting polyacetal having a melt flow rate of 5 g / min or more at 0 ° C or lower. Therefore, the core of the optical fiber 15, the cladding portion 15a and the coating layer 15b are melted and deformed by the heat of the molding die 23 and the polyacetal, and the optical fiber 15 is filled before the polyacetal is filled because the injection speed of the polyacetal is slow. It can be prevented from being deformed. Therefore, the molding material of the connector body 16 having a high melting temperature can be used, and the heat resistant temperature of the connector body 16 can be increased. Furthermore, since the connector body 16 is formed integrally with the optical fiber 15 by injection molding, the coupling force with the optical fiber 15 becomes strong and it becomes difficult to remove it. for that reason,
Even if the connector is repeatedly attached to and detached from other devices, the output of the optical fiber 15 hardly changes. In addition, the number of parts is small, miniaturization is possible, and manufacturing is easy.

FIG. 3 shows a connector body obtained according to another embodiment of the present invention. That is, this connector body
26 is not a mold 23 having two injection ports 24 as shown in FIG. 2, but a mold having a substantially ring-shaped injection gate composed of a plurality of wide injection ports around the optical fiber 15 (see FIG. (Not shown), so that a substantially ring-shaped protrusion 27 corresponding to the shape of the injection gate protrudes from the rear end portion toward the outer peripheral side. This connector body 26
The connecting portion 28 of FIG. 4 is constructed similarly to the connecting portion 8 of the connector 1 of FIG. The molding of the connector body 26 is performed by injecting a molding resin material toward the baffle plate from a substantially ring-shaped injection gate so as to be orthogonal to the optical fiber 15 as in the above-described embodiment. Therefore,
When the molding resin material collides with the baffle plate and loses its momentum, it is injected in a uniform state so as to cover the periphery of the optical fiber 15, and the optical fiber 15 is ejected by the flow pressure of the molding resin material. There will be no eccentricity in the direction. Other functions and effects are similar to those of the above embodiment.
When the ring-shaped projection 27 of the connector body 26 is used, it is cut off. The optical transmission loss of the optical fiber 15 using the connector body 26 was 2.8 dB.

Further, as a method of fixing the connector body to the optical fiber 15, there is a method of bonding the optical fiber 15 and the molding material in addition to utilizing the molding shrinkage of the molding material as described above. That is, there are a method of using an adhesive resin as a connector molding material, a method of using a mixture of the above molding material with an adhesive resin, and a method of using a mixture of the above molding material with a coupling agent. Of the above methods, thermoplastic urethane resin, epoxy resin, and unsaturated polyester resin can be used in the above method, and in the method, 10 parts of epoxy-based, acrylic-based, unsaturated polyester-based resin, etc. can be used per 100 parts of molding material. Mixtures of up to 50 parts can be used. In the method of molding material 10
For 0 parts, silane-based and titanium-based coupling agents
A mixture of 0.1 to 5 parts can be used. The performances and effects of the coupling force of the connector body thus obtained to the optical fiber 15 and the like are the same as those of the connector bodies 16 and 26 of the above embodiment.

The core and the cladding 15a may be made of plastic such as acrylic or polycarbonate or glass fiber, and the coating layer 15b may be made of polyethylene, polyvinyl chloride or the like. Also, the connector body 16,2
As the material of 6, in addition to the above, thermoplastic resins such as polyethylene terephthalate (molding shrinkage 1 to 2) and polypropylene, and other thermosetting resins can be used. Polyethylene, polyvinyl chloride, etc. can be used. In addition, the injection port of the mold is
It may be configured by two pieces as in the above-described embodiment, or may be formed in a substantially ring shape, and may be provided by three pieces at a constant interval, four pieces, or more pieces may be provided.

〔The invention's effect〕

As described above, according to the present invention, the connector for optical fiber is manufactured by using the special mold having the following configurations (a) and (b).

(A) In the peripheral wall surface of the molding die, injection ports are formed facing the optical fibers at the portions facing each other across the optical fiber.

(B) At the outlet of the inlet, a baffle plate is provided so that the molding resin material collides with itself and changes its direction, and flows along the longitudinal direction of the optical fiber.

Therefore, the following effects can be obtained. That is, at the time of molding, the molding resin material injected from the injection port collides with the baffle plate to reduce the momentum (the above configuration (b)) and changes its direction so that it extends along the longitudinal direction of the optical fiber. It will flow. Then, a pair of injection ports are formed in the portion of the peripheral wall of the molding chamber facing each other (the above configuration (a)).
Therefore, the molding resin material that flowed in from the inlet facing each other contacted the flow of molding resin material that flowed in from the inlet in the opposite direction, was regulated in the flow direction, and moved along the longitudinal direction of the optical fiber. It begins to flow in a laminar state.
As a result, the flow pressure of the molding resin material flowing in from the injection port is evenly applied to the optical fiber, and the eccentricity of the optical fiber is prevented. Therefore, the optical fiber connector obtained according to the present invention does not cause photoelectric transmission loss due to eccentricity of the optical fiber.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a connector obtained according to an embodiment of the present invention, FIG. 2 is a vertical sectional view for explaining a manufacturing method thereof, and FIG. 3 is a sectional view of another embodiment of the present invention. FIG. 4 is a perspective view of the obtained connector, FIG. 4 is an exploded perspective view of a conventional connector, FIG. 5 is a longitudinal sectional view showing a method of manufacturing a connector according to another conventional example, and FIG. 6 is a connector according to still another conventional example. FIG. 6 is a vertical cross-sectional view showing the manufacturing method of. 15 …… Optical fiber, 15a …… Core, cladding part, 15b…
… Covering layer, 16… Connector body, 23… Mold, 25…
... baffle

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Katsuyoshi Urano 3600 Gyokutsuyama, Komaki City, Aichi Prefecture Totsugu Rubber Industry Co., Ltd. (56) Reference JP 61-137110 (JP, A) JP Sho 60-257410 (JP, A) JP-A-56-155911 (JP, A)

Claims (1)

[Claims] 1. An optical fiber provided with a fiber core wire and a coating layer on the outer periphery thereof is prepared, a coating layer at an end portion of the optical fiber is removed, and a tip of the end portion is an end of a molding die for forming a connector. The end portion side of the optical fiber is linearly arranged in the molding die in a state of being directed toward the side, and the connector molding resin material is press-fitted into the molding die from the injection port provided in the molding die. According to the method of manufacturing an optical fiber connector in which a connector is integrally molded on the end side of the optical fiber by means of the above, as the molding die, an injection port is provided at each portion of the peripheral wall surface of the molding chamber, which sandwiches the optical fiber. The baffle plate portion is formed so as to face the optical fiber, and the molding resin material collides with itself to change its direction and flow along the longitudinal direction of the optical fiber. Manufacturing method of connector for fiber optic characterized by Rukoto.