JPH0627885B2 - Manufacturing method of optical fiber connector - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method of manufacturing a connector for an optical fiber, which is attached to an end of an optical fiber made of plastic to connect the end of the optical fiber.

[Conventional technology]

In recent years, optical fibers have been favored as communication cables in information communication systems, and from the viewpoint of cost and the like, optical fibers made of plastic have been used in place of the optical fibers made of glass fiber. Since such an optical fiber is laid over a long distance, it is used by connecting the optical fibers to each other or manufacturing them in other devices. A connector 1 as shown in FIG. 5 is used for connecting such an optical fiber. That is, the connector 1 is composed of a main body 4 including a fixing portion 2 and a connecting portion 3, and a lid portion 6 that can be fitted into a recess 5 provided on the upper surface of the fixing portion 2. Reference numeral 7 is an engaging projection alternately provided on both side walls along the longitudinal direction of the recess 5 at predetermined intervals, and 8 is a hole penetrating the recess 5 from one end 2a of the fixing portion 2. The optical fiber core wire 9 can be inserted into the hole portion 8, and the fixing portion 2
Even from the concave portion 5 to the connecting portion 3, a hole portion having the same diameter as the hole portion 8 (not visible because it is hidden in the figure) is bored. 10
Is a cylindrical protrusion protruding from the other end 3a of the connecting portion 3, and its center hole 10a communicates with the hole formed from the recess 5 to the connecting portion 3, and the optical fiber core wire A core and a cladding portion (a core portion having a high refractive index of light which is surrounded by a cladding portion having a low refractive index and is a fiber portion of an optical fiber) 9a which is a central portion of 9 can be inserted. ing. Reference numeral 11 denotes a plurality of protrusions provided on the back surface of the lid portion 6 so as to fit into the gaps of the engaging projections 7 along the longitudinal direction of the recess portion 5 when the lid portion 6 is fitted into the recess portion 5. It is an engaging part. Engaging claws 12 project toward the inside of the lid portion 6 on both sides of the tip of the engaging portion 11. For this reason, the outer cover 9b on one end side of the optical fiber core wire 9 is removed and inserted into the hole 8, the recess 5 and the hole of the main body 4 on the one end side thereof, and the core and the cladding 9a at the tip thereof are cylindrically projected. It is inserted in the central hole 10 a of the device 10. Then, in this state, the lid 6 is fitted into the concave portion 5 of the fixed portion 2 so that as shown in FIG.
The outer cover portion 9b of the optical fiber core wire 9 can be clamped and fixed at 2. Therefore, in this state, by connecting the connecting portion 3 of the main body 4 to another device or the like, the core and the cladding portion 9a can be connected to the device or the like.

[Problems to be Solved by the Invention]

However, since the connector is attached to the optical fiber core wire 9 by clamping and fixing the outer cover portion 9b of the optical fiber core wire 9 with the engaging claws 12 provided on the lid portion 6, the coupling force is weak. There is a problem that it is easy to come off. Further, the diameter of the central hole 10a is set to be slightly larger than the diameter of the core / clad portion 9a in order to insert the core / clad portion 9a into the central hole 10a of the cylindrical projection 10. Therefore, when the core and the cladding portion 9a are eccentrically positioned in the central hole 10a and the optical fibers are connected to each other, there is a problem that the axis shift becomes large and the optical transmission loss becomes large. Further, there is also a problem that water penetrates into the gap between the core / clad portion 9a and the cylindrical protrusion 10, which adversely affects optical transmission.

On the other hand, the end of the optical fiber is positioned in the molding die, and the optical fiber is pinched and supported by the support pins from above and below. A technique of integrally forming a connector at an end has been proposed (Japanese Patent Laid-Open No. 61-3711).
No. 10). According to this technique, since the connector is integrally provided at the end of the optical fiber,
As in the conventional example shown in the figure, the problem that the optical fiber is easily detached from the connector, the problem that the optical fiber is misaligned, and the problem that water enters through the gap between the optical fiber core wire and the covering part Will be resolved. However, there is a problem that water gradually enters through the gap between the end portion of the connector and the optical fiber, and the optical fiber easily breaks from that portion.

[Means for Solving the Problems]

In order to achieve the above object, the manufacturing method of the connector for optical fiber of the present invention is such that the tip side of the optical fiber is inserted into the molding chamber, and the pins are respectively extended from the portions of the wall surface of the molding chamber facing each other. By sandwiching the optical fiber at the tip and press-fitting the molding material into the molding chamber in that state, a solid connector with the traces of the above pins forming a pair of engagement holes is integrated on the tip side of the optical fiber. After molding, attach the tubular boot material to the outer peripheral portion of the connector, cover the base of the optical fiber extending from the connector and the outer peripheral portion of the connector, and in that state, remove the pair of protrusions formed on the inner wall surface of the tubular boot material. The tubular boot member is detachably fixed to the connector by engaging with a pair of engaging holes formed in the outer peripheral portion of the connector.

[Action]

According to the method of manufacturing the connector for optical fiber of the present invention, the tip of the optical fiber is inserted into the molding chamber and the connector is integrally molded on the outer periphery thereof. Does not cause the problems of easy detachment from the connector, the problem of misalignment of the optical fiber axis, and the drawback of water intruding between the optical fiber core wire and the coating layer covering it. In addition, at the time of molding, use a pin that holds the tip of the optical fiber, and on the outer periphery of the solid connector provided on the tip side of the optical fiber, engage the pair of pin marks on the outer periphery of the connector in the same way as when molding the connector. The cylindrical elastic boot material is formed as a hole, and a pair of protrusions on the inner wall surface of the cylindrical elastic boot material attached to the outer periphery of the connector are engaged with the engaging hole to detachably attach the cylindrical elastic boot material to the connector. As a result, at the end of the connector, moisture that gradually enters through the gap between the connector and the optical fiber is prevented, and at the same time, even if a strong shock is applied, the optical fiber may break from this part. Disappear.

Next, this description will be described in detail based on examples.

〔Example〕

FIG. 1 shows an embodiment of the present invention. In the figure, reference numeral 21 denotes an optical fiber core wire formed by coating an optical fiber with an outer skin portion 21b. A core made of a methacrylic resin having a diameter of 980 μm is covered with a cladding made of a foot margin resin having a thickness of 20 μm. The cladding 21a (optical fiber) is covered with a polyethylene outer skin 21b. The optical fiber core wire 21 has an outer skin portion 21b removed from one end thereof, and a core and a cladding portion 21a are exposed in the removal mark. Reference numeral 22 is a polyacetal connector, which is the optical fiber core wire 2 described above.
It is formed in a state in which the boundary portion between the outer side of the outer skin portion 21b of No. 1 and the exposed side of the core and the cladding portion 21a is covered. The connector 22 is formed with a connecting portion 23 having a small diameter on the front end side, and a recess 23a is coaxially provided on the front end side of the connecting portion 23. A cylindrical projection 24 for fitting the core and the cladding 21a is projected from the center of the bottom surface of the recess 23a. Reference numeral 25 denotes a pair of cylindrical hole portions provided on the outer periphery of the rear end side of the connector 22 at right angles to the axis,
Relative from the top and bottom. 26 is the outer cover 21b of the optical fiber core 21 from the rear end side of the connector 22.
A cylindrical rubber boot for connector protection attached to the outer periphery on the remaining side, and two cylindrical protrusions 27 protruding from the inner peripheral surface are fitted into the cylindrical hole 25 of the connector 22. It is attached so that it can be attached and removed freely.

Such a connector is obtained as follows.
That is, first, the outer skin portion 21b on one end side of the optical fiber core wire 21 is removed to expose the core and the cladding portion 21a. Next, a molding die 28 as shown in FIG.
Temperature below the softening temperature of the cladding portion 21a (outer skin portion 21b
Is set to a higher temperature than the softening temperatures of the core and the cladding portion 21a), and the boundary between the remaining portion of the outer skin portion 21b of the optical fiber core 21 and the exposed portion of the core and the cladding portion 21a is set in the molding die 28. Arrange the parts. Then, the remaining portion of the outer skin portion is supported and fixed so as not to be eccentric by sandwiching the pin 29 provided on the molding die 28. The columnar pin 29 has a function of releasing the heat in the molding die 28 to the outside at the same time as fixing the optical fiber core wire 21.
8 and the tip projects outside the molding die 28.
Next, in that state, the molding space 28 of the molding die 28
The liquid nopolyacetal having a melt flow rate of 5 g / min or more is injected from the injection port 30 to the softening temperature + 150 ° C., and a connector 22 having the same shape as the molding space 28a is formed on the outer periphery of the boundary portion. Form.
During the formation, when the liquid polyacetal is solidified, contraction (molding contraction rate of 2.5% or more) occurs, so that the optical fiber core wire 21 is firmly fixed to the connector 22. Next, the core protruding from the cylindrical projection 24 of the connector 22 and the cladding portion 21a are cut off, and a tubular rubber boot portion 26 is formed in advance.
The boot portion 26 as shown in FIG.
A connector protected by coating is obtained. By connecting the connecting portion 23 of this connector to another connector or device, the tip of the core / clad portion 21a can be connected to the core / clad of another optical fiber.

The output fluctuation (dB) of the optical fiber core wire 21 when repeatedly attached to and detached from a device or the like by using the connector thus covered and protected by the boot portion 26
Shown in the figure. As shown in the figure, almost no output fluctuation was observed even after the attachment / detachment was repeated 500 times. A pull-out test was conducted by pulling the connector and the optical fiber core wire 21 in opposite directions, and the results shown in FIG. 4 were obtained. That is, first, a load of slightly over 4 kg was applied and maintained for 1 minute, and then the load was increased to 7 kg and maintained for 1 minute. Next, when increasing the load,
The optical fiber core wire 21 begins to expand at 13 kg, but the optical fiber core wire 21 does not come off from the connector. Since the connector 1 of the conventional example shown in FIG. 5 is detached from the optical fiber core wire 9 by applying a load of 7.5 kg, the connector of the present invention has sufficient pull-out strength to withstand use. I can say.

〔The invention's effect〕

The manufacturing method of the optical fiber connector of the present invention is such that the tip of the optical fiber is inserted into the molding chamber and a solid connector is integrally molded on the outer periphery thereof, so that the optical fiber is easily detached from the connector. It does not suffer from the drawback of axial misalignment and the ingress of water between the optical fiber core wire and the coating layer covering it. In addition, a pin that holds the tip of the optical fiber is used to form a pair of engagement holes on the outer periphery of the solid connector at the same time as molding of the connector, and a pair of engagement holes are formed in the engagement hole. The elastic boot material is detachably attached to the connector by engaging a pair of protrusions on the inner wall surface of the boot material. Therefore, at the end of the connector, moisture that gradually penetrates through the gap between the connector and the optical fiber is prevented, and at the same time, even if a strong impact is applied, the optical fiber does not break from this part. .

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of an embodiment of the present invention, FIG. 2 is a vertical cross-sectional view for explaining the manufacturing method thereof, and FIG. FIG. 4 is a curve diagram showing the pull-out strength, FIG. 5 is an exploded perspective view of a conventional example, and FIG. 6 is a longitudinal sectional view of a main part thereof. 21 ... Optical fiber core wire, 21a ... Core, cladding part, 21b ... Outer skin part, 22 ... Connector, 29 ...
pin

Claims (1)

[Claims] 1. A tip end side of an optical fiber is inserted into a molding chamber, pins are respectively extended from portions of the wall surface of the molding chamber facing each other, and the optical fiber is sandwiched at the tip, and molding is performed in that state. By press-fitting the material for use, on the tip side of the optical fiber, a solid connector in which the traces of the pins are a pair of engagement holes is integrally molded, and the tubular boot material is attached to the outer peripheral portion of the connector, Cover the root of the optical fiber extending from the connector and the outer periphery of the connector,
In this state, the pair of protrusions formed on the inner wall surface of the tubular boot material are respectively engaged with the pair of engagement holes formed on the outer peripheral portion of the connector, so that the tubular boot material can be detachably attached to the connector. A method of manufacturing a connector for optical fiber, which is characterized by fixing.