JPH02165109A - Production of connector for optical fiber - Google Patents

Abstract

PURPOSE:To prevent the eccentricity of an optical fiber and to prevent the generation of a light transmission loss by providing a baffle plate part to the outlet side of an injection port and injecting a molding resin material toward the baffle plate part in such a fluid pressure state that the material is symmetrical with the optical fiber as a center, thereby integrally molding the connector on the outer periphery of the optical fiber. CONSTITUTION:The optical fiber 15 is linearly disposed in a forming mold 23 and the baffle plate part 25 is provided to the outlet part of the injection port 24 of the mold 23. The molding resin material is injected from the injection port 24 provided to face the baffle plate part 25 so as to come into contact therewith to press-feed the molding resin material into the mold 23, by which the connector 16 is integrally molded on the outer periphery of the optical fiber 15. The molding resin material ejected in the mold 23 collides against the baffle plate part 25 and while the energy thereof is offset, the material infiltrates into successively the deep side of the forming chamber 23a in the symmetrical fluid pressure state on both sides of the optical fiber 15. As a result, the fluid pressure of the molding resin material is exerted uniformly on the outer periphery of the optical fiber 15 and the eccentricity to one direction is obviated. The generation of the transmission loss by the eccentricity is prevented in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for manufacturing an optical fiber connector that is integrally attached to the ends of optical fibers and connects the ends of the optical fibers.

[Conventional technology]

In recent years, optical fibers have been prized as communication cables in information and communication systems, and since such optical fibers are laid over long distances, it is difficult to connect optical fibers to each other or to other devices. It is used as And for such optical fiber connections,
A connector 1 as shown in FIG. 4 is used. That is, this connector 1 is composed of a main body 3 having a recess 2 on its upper surface, and a lid 4 that can be fitted into the recess 2 of the main body 3. A plurality of engagement claws 7 are provided on the lower surface of the lid portion 4 and can clamp and fix the optical fiber 6 with the engagement protrusion 5.
There are multiple protruding pieces. The distal end side of the main body 3 is formed into a square cylindrical connecting part 8, and a cylindrical protrusion 9 is formed from the inside thereof.
stands out. The center hole 9a of the cylindrical protrusion 9 is formed by the core, which is the central part of the optical fiber 6, and the cladding part (the core part with a high refractive index of light is surrounded by the cladding part with a low refractive index). A hole 10 (the hole on one end of the main body 3 (not visible) is provided coaxially with the center hole 9a. Therefore, the outer skin part 6b on one end side of the optical fiber 6 is removed, the one end side is inserted into the hole part 10 of the main body 3 from the other end side, and the core and cladding part 6a at the tip are inserted into the center hole 9a of the cylindrical projection 9. By fitting the lid 4 into the recess 2 of the main body 3 in the inserted state, the outer skin 6b of the optical fiber 6 can be clamped and fixed between the engaging claw 7 of the lid 4 and the engaging protrusion 5 of the main body 3. . As a result, in this state, by connecting the connecting portion 8 of the main body 3 to another device, etc., the core and cladding portion 6a can be connected to the device, etc. mentioned above.

However, since the connector 1 is attached to the optical fiber 6 by clamping and fixing the outer skin part 6b of the optical fiber 6 between the engaging claw 7 provided on the lid part 4 and the engaging protrusion 5 of the main body 3, When a tensile force is applied and exceeds the frictional locking force between the outer skin portion 6b, the engaging claw 7, and the engaging protrusion 5, there is a problem that the optical fiber 6 easily comes off. Another problem is that the number of parts increases and the connector 1 itself becomes large. Therefore, the present inventors have devised an optical fiber connector in which a connector is integrally formed on the end side of an optical fiber as a connector for optical fiber that can solve the above-mentioned problems, and have already filed an application (Utility Application No. 63-20
No. 152).

That is, as shown in FIG. 5, in this optical fiber connector, the end side of the optical fiber 6 is placed in the mold 11, and in that state, the connector is inserted into the space 13 in the mold 11 through the injection port 12. A resin liquid for molding is injected, and a connector is integrally formed on the end side of the optical fiber 6.

[Problem that the invention seeks to solve]

However, in the optical fiber connector described above, when the resin liquid for connector molding is injected into the mold 11, the flow pressure causes the core and the cladding part 6a to bend and become eccentric. As a result, a problem arises in that the optical transmission loss increases (as a result of a test, the optical transmission loss in this case was 9.2 dB). Therefore, as shown in FIG. 6, an injection port 12a was provided at a portion corresponding to the root side of the optical fiber 6, so that the resin liquid could be injected in parallel to the optical fiber 6, and the connector was molded. As a result, the optical transmission loss of the obtained connector was 4.5
dB, but further improvement is desired.

The present invention was made in view of the above circumstances, and an object thereof is to provide a method for manufacturing an optical fiber connector that can prevent the occurrence of optical transmission loss due to eccentricity.

[Means for solving problems]

In order to achieve the above object, the method for manufacturing an optical fiber connector of the present invention involves preparing an optical fiber having a fiber core and a coating layer on its outer periphery, removing the coating layer at the end of the optical fiber, and removing the coating layer from the end of the optical fiber. Place the end of the optical fiber in a straight line in the mold with the tip of the optical fiber facing toward the end of the mold for forming the connector, and insert the fiber into the mold through the injection port provided in the mold. A manufacturing method for an optical fiber connector, in which a connector is integrally molded on the end side of the optical fiber by press-fitting a resin material for connector molding into the mold, and the mold is formed by pouring into opposing parts of the peripheral wall surface of the molding chamber. An inlet is formed, a baffle plate portion is formed at the outlet of the injection port, and the molding resin material is injected after coming into contact with the baffle plate.

[Effect]

That is, the method for manufacturing an optical fiber connector of the present invention involves arranging optical fibers in a straight line in a mold, providing a baffle plate portion at the outlet of the injection port of the mold, and making contact with the baffle plate portion. By injecting the molding resin material from injection ports provided oppositely to each other, the molding resin material is press-fitted into the mold and a connector is integrally formed around the outer periphery of the optical fiber. Therefore, the molding resin material injected into the mold collides with the baffle plate, loses its momentum, and enters the back of the forming chamber with symmetrical fluid pressure across the optical fiber. become. As a result, the flow pressure of the molding resin material is uniformly applied to the outer periphery of the optical fiber, and the optical fiber is prevented from being eccentric in one direction due to the flow pressure.

Therefore, it is possible to prevent optical transmission loss from occurring due to eccentricity.

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

〔Example〕

FIG. 1 shows a connector obtained according to an embodiment of the present invention. In the figure, 15 is the core, cladding 1
5a (fiber core wire) coated with an outer skin part 15b, the periphery of a methacrylic resin core with a diameter of 980 μm is covered with a fluoride resin cladding with a thickness of 20 μm, and this core, The clad 15a is surrounded by a polyethylene outer cover 15b. This optical fiber 15 has an outer skin portion 1 on one end side.
5b is removed, and the core and cladding portion 15a are left in the removal trace.
is exposed. Reference numeral 16 denotes a connector body made of polyacetal, which is integrally formed to cover the boundary between the remaining outer skin 15b of the optical fiber 15 and the exposed side of the core and cladding 15a. The connector main body 16 has a connecting portion 17 having a small diameter at the distal end, and a ring-shaped groove 18 is provided along the circumference on the inner peripheral side of the rear end. There are four parts 17 on the tip side of the connecting part 17.
a, and from the center of the bottom surface of the recess 17a is a cylindrical protrusion 19 that coaxially houses the core and cladding part 15a.
stands out. Reference numeral 20 denotes a rubber boot part for protecting the connector which is removably attached to the outer periphery of the remaining outer skin part 15b of the optical fiber 15 from the rear end side of the connector body 16, and is attached to the rear end side of the connector body 16. The connector body 16 is attached with a ring-shaped protrusion 22 provided on the bottom surface of the recess 21 fitted into the groove 18 of the connector body 16.

Such a connector can be manufactured as follows. That is, first, the outer skin portion 15b on one end side of the optical fiber 15 is removed to expose the core and cladding portion 15a. Next, a mold 23 as shown in FIG. 2 is set at a temperature lower than the softening temperature of the core and cladding portion 15a (the softening temperature of the outer skin portion 15b is higher than that of the core and cladding portion 15a), and the molding is performed. The optical fiber 15 is placed in the mold 23 with the boundary portion between the remaining portion of the outer skin portion 15b and the exposed portion of the core and cladding portion 15a extending linearly. Then, in this state, the temperature is set to the softening temperature +150° C. or lower from the injection ports 24, which are vertically symmetrically provided in the molding space 23a of the mold 23 so as to sandwich the optical fiber 15 between them, and the melt flow rate is 5 g. /min or more of liquid polyacetal is injected perpendicularly to the optical fiber 15 to form a connector body 16 having the same shape as the molding space 23a on the outer periphery of the boundary portion. In addition, a ring-shaped covering portion 25 is protruded at a portion of the mold 23 corresponding to the root side of the optical fiber 15 with its inner peripheral surface flush with the optical fiber fixing hole 23b of the mold 23. This covers the root side of the optical fiber 15. Therefore, during the above-mentioned formation, the liquid polyacetal injected from the two injection ports 24 provided vertically symmetrically collides with the covering portion 25 and advances toward the back side of the molding space 23a with its momentum being lost. Then, the connector body 16 is formed. Further, at this time, since liquid polyacetal is injected from the two upper and lower injection ports 24, fluid pressure is evenly applied to the upper and lower sides of the optical fiber 15, and the linearity of the optical fiber 15 is maintained appropriately. Furthermore, when the liquid polyacecool solidifies, shrinkage (molding shrinkage rate of 2.5 or more) occurs, so the optical fiber 15
It becomes firmly fixed to the connector body 16. Next, the core and cladding portion 15a protruding from the cylindrical protrusion 19 of the connector body 16 are cut out, and a pre-formed rubber boot portion 20 is fitted into the first
A connector as shown in the figure is obtained. By connecting the connecting portion 17 of this connector to another connector, device, etc., the tip of the core/cladding portion 15a can be connected to the core, cladding, etc. of another optical fiber. Note that during the connector molding, the temperature of the mold 23 rises due to the heat of the polyacecool, but this is cooled by water cooling etc. in preparation for the next use, thereby maintaining the temperature below the softening temperature of the optical fiber 15 at all times.

As a result of testing using the connector thus obtained, the optical transmission loss of the optical fiber 15 was 2.7 d.
It was B. Moreover, as a result of repeatedly attaching and detaching the above connector to and from equipment, almost no output fluctuation was observed. Furthermore, a pullout test was conducted in which the connector and the optical fiber 15 were pulled in opposite directions. That is,
First, apply a load of over 4 kg and maintain it for 1 minute.
The load was then increased to 7 kg and maintained for 1 minute. Next, when increasing the load, at 13 kg, 1 optical fiber
5 began to stretch, but the optical fiber 15 did not come off from the connector. The conventional connector 1 shown in FIG.
．． By adding a load of 5 kg, the optical fiber 6
Therefore, it can be said that the connector of the present invention has sufficient pull-out strength to withstand use. Note that the above connector is made of nylon (molding shrinkage rate 0.3 to 0.
8%), the pullout force was 8.7 kg, and when the molding shrinkage rate was 1.0 to 1.5%, the pullout force was 13.0 kg.

In this way, this connector is manufactured by inserting the optical fiber 15 into the mold 2 with the root side covered with the ring-shaped covering part 25.
The molded resin material is injected toward the coating part 25 from two injection ports 24 arranged vertically symmetrically so as to sandwich the optical fiber 15 in a straight line within the optical fiber 15, thereby integrally forming the molded resin material at the end of the optical fiber 15. It is formed. Therefore, during the molding of the connector, the flow pressure of the molding resin material is uniformly 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 from occurring due to eccentricity. In addition, this connector is made by setting the temperature of the mold 23 below the softening temperature of the core and cladding part 15a of the optical fiber 15, and using polyacetal whose temperature is below the above-mentioned softening temperature +150°C and whose melt flow rate is 5 g/min or above. Manufactured by injection. Therefore, the core, cladding portion 15a, and outer skin portion 15b of the optical fiber 15 may be melted and deformed by the heat of the mold 23 and polyacetal, and the optical fiber 15 may be deformed before being filled with polyacetal because the injection speed of polyacetal is slow. This can be prevented. Further, for this reason, a material with a high melting temperature can be used as the molding material for the connector body 16, and the heat resistance temperature of the connector body 16 can be increased. Furthermore, since the connector main body 16 is molded integrally with the optical fiber 15 by injection molding, the bonding force with the optical fiber 15 is strong and it becomes difficult to separate. Therefore, even if the connector is repeatedly connected to and disconnected from other devices, almost no output fluctuation occurs in the optical fiber 15. Also,
It has fewer parts, can be made smaller, and is easier to manufacture.

FIG. 3 shows a connector body obtained according to another embodiment of the invention. That is, this connector main body 26 does not have a mold 23 having two injection ports 24 as shown in FIG. It is molded by a mold (not shown), and therefore a substantially ring-shaped projection 27 corresponding to the shape of the injection gate protrudes from the rear end toward the outer periphery. The connecting portion 2 of the connector main body 26 is constructed similarly to the connecting portion 8 of the connector 1 shown in FIG. 4. This connector body 2
The molding of No. 6 is carried out by injecting the molding resin material from a substantially ring-shaped injection gate toward the coating portion orthogonally to the optical fiber 15, as in the above embodiment. Therefore, the molded resin material collides with the covering part and loses its momentum, and is ejected in a uniform manner so as to cover the periphery of the optical fiber 15, and the optical fiber 15 is unidirectionally moved by the flow pressure of the molded resin material. This eliminates the possibility of eccentricity. Other effects are the same as in the above embodiment. Note that the ring-shaped protrusion 27 of the connector body 26 is cut off when used. Further, the optical transmission loss of the optical fiber 15 using this 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 using the molding shrinkage of the molding material as described above. Namely, ■method of using an adhesive resin as a connector molding material, ■method of using a mixture of the above-mentioned molding material with adhesive resin, and ■method of using a mixture of the above-mentioned molding material with a coupling agent. It is. Among the above methods, thermoplastic urethane resin, epoxy resin, unsaturated polyester resin can be used in method (■), and in method (2), epoxy resin, acrylic resin, unsaturated polyester resin, etc. can be used for 100 parts of molding material. A mixture of 10 to 50 parts of these can be used. In method (2), it is possible to use a mixture of 0.1 to 5 parts of a silane-based or titanium-based coupling agent to 100 parts of the molding material. Optical fiber 1 of the connector body obtained in this way
The performance and effects such as the coupling force to the connector body 5 are the same as those of the connector bodies 16 and 26 of the above embodiment.

The materials constituting the core and cladding 15a are as follows:
Plastics such as acrylic and polycarbonate and glass fibers can be used, and the outer skin portion 15b can be made of polyethylene,
Polyvinyl chloride etc. can be used. In addition to the materials mentioned above, thermoplastic resins such as polyethylene terephthalate (molding shrinkage rate 1 to 2), polypropylene, and other thermosetting resins can be used as the material for the connector body 16.26. In addition to rubber, polyethylene, polyvinyl chloride, etc. can be used as the material. In addition, the injection ports of the mold may be configured with two as in the above embodiment, or may be formed approximately in a ring shape, or may be provided with three injection ports at regular intervals, or may be formed with four injection ports at regular intervals.
It may be configured by providing one or a large number of them.

[Effects of the Invention] As described above, the method for manufacturing an optical fiber connector of the present invention provides a baffle plate portion on the outlet side of an inlet, and directs the flow toward the baffle plate portion under a fluid pressure state that is symmetrical around the optical fiber. By injecting a molding resin material, the connector is integrally formed around the outer circumference of the optical fiber. Therefore, the molded resin material collides with the baffle plate portion and loses its momentum, and the fluid pressure is uniformly applied to the optical fiber, thereby preventing eccentricity of the optical fiber. As a result, the occurrence of optical transmission loss is extremely reduced.

[Brief explanation of the drawing]

FIG. 1 is a vertical cross-sectional view of a connector obtained according to one embodiment of the present invention, FIG. 2 is a vertical cross-sectional view illustrating its manufacturing method, and FIG. 3 is a longitudinal cross-sectional view of a connector obtained according to another embodiment of the present invention. FIG. 4 is an exploded perspective view of a conventional connector, FIG. 5 is a vertical cross-sectional view showing another conventional method of manufacturing a connector, and FIG. 6 shows a further method of manufacturing a connector according to another conventional example. FIG. 15... Optical fiber 15a... Core, clad part 15b... Outer skin part 16... Connector body
23...Molding mold 25...Coating portion Patent applicant Tokai Rubber Industries Co., Ltd. Agent Patent attorney Yukihiko Nishifuji Figure 3

Claims (1)

[Claims] (1) Prepare an optical fiber with a fiber core and a coating layer around its outer periphery, remove the coating layer from the end of this optical fiber, and direct the tip of the end toward the end side of the mold for forming a connector. In this state, the end side of the optical fiber is arranged in a straight line in the mold, and a resin material for connector molding is press-fitted into the mold from the injection port provided in the mold, thereby forming the end of the optical fiber. A method for manufacturing an optical fiber connector in which a connector is integrally molded on the side of the molding chamber, and the mold has an inlet formed in opposing parts of the peripheral wall of the molding chamber, and a baffle plate part at the outlet of the inlet. A method for producing an optical fiber connector, characterized in that the resin material for molding is injected after contacting the baffle plate.