JPH0921928A - Ferrule for single fiber optical connector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to prevent the occurrence of peeling and shaking between a specific cylindrical sleeve consisting of ceramics, metals, etc., and a plastic resin by forming the cylindrical sleeve of an insert-molded plastic resin. SOLUTION: The plastic resin 23 is packed into the ceramic cylindrical sleeve 22 constituting the outer peripheral part of a ferrule 20 and the axial center thereof is provided with an optical fiber insertion hole 21. The cylindrical sleeve 22 and the plastic resin 23 are integrally formed by insert molding. The outside surface at the front end of the cylindrical sleeve 22 is formed to a tapered shape having the diameter reducing toward the front of the ferrule 20 and the front end is embedded into the plastic resin 23. The rear end of the cylindrical sleeve 22 connected to a collar part 30 continuous with the rear part of the ferrule 20 is covered with the plastic resin 23. Further, the collar part 30 is provided with a coated optical fiber insertion hole 31 at its axial center. This insertion hole 31 is communicated to the optical fiber insertion hole 21 through the optical fiber insertion hole 24 of the ferrule 20.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ferrule for a single-fiber optical connector, which is attached to the ends of optical fibers and used for connecting optical fibers to each other.

[0002]

2. Description of the Related Art FIG. 6 shows a typical single-fiber optical connector which is attached to the ends of optical fibers and is used for connecting optical fibers to each other. The single-fiber optical connector 60 shown in FIG. 6 includes a ferrule for a single optical connector (hereinafter simply referred to as a ferrule) 61 at a tip portion and a collar portion 62 at a rear end portion. An optical fiber insertion hole 63 into which a bare optical fiber is inserted and fixed is provided at the center of the ferrule 61 at the tip end portion. An optical fiber core wire insertion hole 64 into which a portion having a coating provided on the outer periphery of the optical fiber is inserted and fixed is provided at the center of the flange portion 62 at the rear end, and the optical fiber insertion hole 63 and the optical fiber are inserted. A central axis (hereinafter, simply referred to as an axis) is aligned with the core wire insertion hole 64 and communicates with each other in the single-core optical connector 60. In the single-fiber optical connector 60 as described above, the axial center of the outer peripheral surface of the ferrule 61, which is the reference surface (hereinafter simply referred to as the outer peripheral axis), and the axial center of the optical fiber insertion hole 63 match with high accuracy without eccentricity. Is required.

For example, the ferrule 61 is ceramics,
When it is made of metal or glass, the optical fiber insertion hole 63 is ground after the outer periphery is machined, so that the optical fiber insertion hole 6 and the axial center of the outer periphery of the ferrule 61 are machined.
Although the axes of 3 can be aligned with high accuracy, they are not suitable for mass production and are expensive because they are machined. Further, a ferrule in which the entire ferrule 61 is entirely molded with a plastic resin is also proposed. The ferrule molded from only this plastic resin has the advantage of being inexpensive because it can be mass-produced, but it has poor mechanical strength and cannot withstand long-term use.

[0004]

In order to make up for these drawbacks, a composite molding type ferrule in which a cylindrical sleeve made of ceramics, metal, glass or the like is insert-molded in a plastic resin is disclosed in, for example, Japanese Patent Application Laid-Open No. 61-61.
It is disclosed in Japanese Patent No. 137109. The composite molding type ferrule in which a cylindrical sleeve made of ceramics, metal, glass or the like is insert-molded has higher strength by insert-molding the cylindrical sleeve, but the cylinder inserted by the shrinkage of the plastic resin during molding. There is a possibility that peeling may occur between the sleeve and the plastic resin, causing rattling, and the cylindrical sleeve may come off. Further, this rattling may make the positional accuracy of the optical fiber insertion hole unstable at the tip of the ferrule, which may adversely affect the connection loss.

The present invention solves the above-mentioned problems, and even if the cylindrical sleeve is insert-molded, the plastic resin shrinks during the molding, so that the cylindrical sleeve and the plastic resin are not separated from each other and rattling is not caused. An object of the present invention is to provide a ferrule for a single-fiber optical connector.

[0006]

The present invention has the following means to solve the above problems.

The ferrule for a single-fiber optical connector according to claim 1 of the present invention is a ferrule for a single-fiber optical connector having an optical fiber insertion hole, and the ferrule for a single optical connector is a cylinder made of ceramics, metal or glass. The sleeve is formed of insert-molded plastic resin, and the cylindrical sleeve is filled with the plastic resin, the front end is embedded in the plastic resin, and the rear end is at least the rear end surface of the plastic resin. It is characterized by being covered with.

The ferrule for a single-core optical connector according to a second aspect of the present invention is characterized in that the rear end portion of the cylindrical sleeve is also embedded in the plastic resin.

[0009]

According to the ferrule for a single-core optical connector of claim 1 of the present invention, the optical connector body is formed of the plastic resin obtained by insert molding the cylindrical sleeve made of ceramics, metal or glass. It has sufficient strength compared to a ferrule made entirely of plastic resin molding. Of course, since it is a molded body, it can be mass-produced and is inexpensive. Further, in this ferrule, the cylindrical sleeve is formed by filling the inside thereof with a plastic resin, the front end portion is embedded in the plastic resin, and the rear end portion is covered with the plastic resin at least at the rear end surface. It is possible to prevent the cylindrical sleeve from sticking out due to the contraction of the resin in the longitudinal direction, and also to prevent the cylindrical sleeve and the plastic resin from peeling off due to the contraction of the plastic resin in the radial direction and the rattling associated therewith. In addition, since the front end portion of the ferrule is embedded in the plastic resin, the shrinkage itself of the plastic resin in the radial direction is greatly suppressed. As a result, the concentricity between the axial center of the outer periphery of the tip of the ferrule and the axial center of the optical fiber insertion hole is secured, so that the connection loss between the optical connectors is not increased.

In the ferrule for a single-core optical connector according to claim 2 of the present invention, the rear end portion of the cylindrical sleeve is also embedded in the plastic resin in the same manner as the front end portion. Since the peeling and rattling due to the shrinkage of the plastic resin are prevented and the shrinkage of the plastic resin itself is also suppressed, the cylindrical sleeve and the plastic resin can be integrated more reliably, and the axial center of the optical fiber core wire insertion hole does not fluctuate. Can be prevented.

[0011]

The present invention will be described below in detail with reference to examples. FIG. 1 is a cross-sectional view showing an embodiment of a single-core optical connector 10 in which the ferrule of the present invention is incorporated in a collar portion. The single-fiber optical connector 10 is provided with a ferrule 20 at the front end and a flange 30 connected to the rear of the ferrule 20. The ferrule 20 at the distal end is a cylindrical sleeve 22 to be described later.
Has an optical fiber insertion hole 21 at the axial center of the outer periphery of the. Cylindrical sleeve 22 that forms the outer periphery of the ferrule 20
Is made of, for example, a cylindrical sleeve 22 made of ceramics, the inside of which is filled with a plastic resin 23, and the axial center thereof is the optical fiber insertion hole 2 as described above.
1 is provided. The cylindrical sleeve 22 and the plastic resin 23 are integrally formed by insert molding. The outer surface of the tip of the cylindrical sleeve 22 is a ferrule 2
It has a taper shape in which the diameter decreases toward the front of 0, and this tip end portion is embedded in the plastic resin 23.

Further, the cylindrical sleeve 2 connected to the collar portion 30.
In the rear end portion of 2, the rear end portion of the cylindrical sleeve 22 is covered with the plastic resin 23, and the front end portion, the rear end surface and the inside of the cylindrical sleeve 22 are covered with the plastic resin 23.
It is surrounded by. The outer periphery of the ferrule 20 and the optical fiber insertion hole 21 are concentric. In other words, their central axes are in agreement.

The flange portion 30 of the single-core optical connector 10 is provided with an optical fiber core wire insertion hole 31 into which the optical fiber core wire is inserted, and the optical fiber core wire insertion hole 31.
Is an optical fiber insertion hole 2 provided in the ferrule 20.
4 and communicates with the optical fiber insertion hole 21. this,
The collar portion 30 is formed of, for example, a plastic resin, and the rear end of the ferrule 20 is fitted and connected to the recess 32 of the collar portion 30.

The ferrule 20 is formed as follows, for example. FIG. 2 shows a mold 40 for molding the ferrule 20. The mold 40 includes a fixed mold 41 and a movable mold 4.
It can be divided into two. Optical fiber insertion hole 2 in the fixed side mold 41
1, the molding pin 43 forming the optical fiber insertion hole 24 and the optical fiber core wire insertion hole 31 is set. On the other hand, the cylindrical sleeve 22 is set in the movable side mold 42, and then both the molds 41 and 42 are closed to form the molding pin 43 and the cylindrical sleeve 22.
The ferrule 20 is molded by injecting a plastic resin into the space formed between the ferrules. In FIG. 2, 4
4 is a resin injection gate, 45 is a runner, and 46 is a nest for setting the cylindrical sleeve 22. Reference numeral 47 is a positioning fitting hole for positioning the tip position of the molding pin 43. By accurately disposing the cylindrical sleeve 22 in the nest 46, the axial center of the outer circumference of the cylindrical sleeve 22 and the axial center of the positioning fitting hole 47 at the tip of the molding pin 43 coincide with each other. The center and the axial center of the cylindrical sleeve 22 with the outer peripheral surface as the reference surface coincide with each other.

According to this embodiment, the cylindrical sleeve 22
Since the tip end portion (tapered portion) is embedded in the plastic resin, even if the plastic resin contracts, the cylindrical sleeve and the plastic resin are less likely to peel off and rattling is less likely to occur. Further, at least at the tip end of the ferrule 20 which is the connection end face with the mating optical connector and is most liable to fluctuate in the axial center, the tip end of the cylindrical sleeve (the taper shape) in which the radial shrinkage of the plastic resin itself is embedded in the plastic resin. Is suppressed), the fluctuation of the axial center is suppressed at the tip of the optical fiber insertion hole 21.

FIG. 3 shows a single-core optical connector 10A incorporating a ferrule according to another embodiment of the present invention. In this single-fiber optical connector 10A, the rear end portion of the cylindrical sleeve 22 is tapered in the diameter reducing direction like the front end portion and is embedded in the plastic resin 23A similarly to the front end portion of the cylindrical sleeve 22 shown in FIG. The state of being cut (the state of biting)
It has become. Other configurations are similar to those of the single-fiber optical connector 10 of FIG. 1, and detailed description thereof will be omitted. With this configuration, the cylindrical sleeve is securely held by the plastic resin, and as a result, the cylindrical sleeve and the plastic resin are prevented from peeling and rattling due to the shrinkage of the plastic resin. Further, since the tapered portions at both ends of the cylindrical sleeve also suppress the radial contraction of the plastic resin, it is possible to prevent the axial center of the optical fiber insertion hole or the optical fiber core wire insertion hole from changing.

FIG. 4 shows a single-core optical connector 10B incorporating a ferrule according to another embodiment of the present invention. In this single-core optical connector 10B, a V-groove 25 is provided at the tip of the cylindrical sleeve 22B, and the plastic resin 23B is formed in the V-groove 25. This example also shows an example in which the front end of the cylindrical sleeve is embedded in the plastic resin. Other configurations are similar to those of the single-fiber optical connector 10 of FIG. 1, and detailed description thereof will be omitted.

FIG. 5 shows a single-core optical connector 10C incorporating a ferrule of another embodiment of the present invention. The feature of the ferrule 20C of this single-fiber optical connector 10C is that the ferrule 20C and the collar portion 3 are made of a plastic resin 23C.
0C and 1C are integrally molded. By integrally molding the ferrule and the collar portion in this way, the processing can be performed in one step, and therefore the unit cost of the single-fiber optical connector can be significantly reduced.
Other configurations are similar to those of the single-fiber optical connector 10 of FIG. 1, and detailed description thereof will be omitted. In the above embodiment,
The cylindrical sleeve was made of ceramics,
The cylindrical sleeve is not limited to the one made of ceramics, but the same performance as that of the above-mentioned embodiment can be obtained by using other rigid members such as metal and glass.

[0019]

As described above, according to the ferrule for a single-core optical connector of claim 1 of the present invention, the ferrule is formed of a plastic resin obtained by insert molding of a cylindrical sleeve made of ceramics, metal or glass. Therefore, it has sufficient strength as compared with a product made entirely of a plastic resin molding. Of course,
Since it is a molded body, it can be mass-produced and the price can be reduced. Further, since the tip end of the cylindrical sleeve is embedded in the plastic resin and at least the rear end surface of the rear end portion is also covered with the plastic resin, the protrusion of the cylindrical sleeve due to the contraction of the plastic resin in the longitudinal direction of the ferrule is caused. This prevents the plastic resin from shrinking in the radial direction at the tip, and prevents the plastic sleeve from peeling off from the plastic resin and the rattling that accompanies this. Since the concentricity of the axial center of the holes is secured, the connection loss between the optical connectors is not increased.

In the ferrule for a single-core optical connector according to claim 2 of the present invention, since the rear end portion of the cylindrical sleeve is also embedded in the plastic resin, it is possible to suppress the shrinkage of the plastic resin in the radial direction like the front end portion. , Peeling due to shrinkage of plastic resin and rattling due to this peeling are prevented,
The cylindrical sleeve and the plastic resin can be integrated more reliably, and the fluctuation of the axis of the optical fiber core wire insertion hole can be prevented.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a single-fiber optical connector incorporating a ferrule for a single-fiber optical connector of the present invention.

2 is a cross-sectional view showing an example of a molding die for manufacturing the ferrule of the single-fiber optical connector shown in FIG.

FIG. 3 is a cross-sectional view showing a single-fiber optical connector incorporating another ferrule of the present invention.

FIG. 4 is a cross-sectional view showing a single-fiber optical connector incorporating another embodiment of the ferrule of the present invention.

FIG. 5 is a sectional view showing still another embodiment of the single-fiber optical connector of the present invention.

FIG. 6 is a sectional view showing an example of a conventional single-core optical connector.

[Explanation of symbols]

 10 Single-core optical connector 10A Single-core optical connector 10B Single-core optical connector 10C Single-core optical connector 20 Ferrule 20A Ferrule 20B Ferrule 20C Ferrule 21 Optical fiber insertion hole 22 Cylindrical sleeve 23 Plastic resin 24 Optical fiber insertion hole 30 Collar part 31 Optical fiber Core wire insertion hole

Claims (2)

[Claims] 1. A ferrule for a single optical connector having an optical fiber insertion hole, wherein the ferrule for a single optical connector is formed of a plastic resin obtained by insert molding a cylindrical sleeve made of ceramics, metal or glass. A single-fiber optical connector, wherein the cylindrical sleeve is filled with the plastic resin, the front end portion is embedded in the plastic resin, and the rear end portion is covered with the plastic resin at least on the rear end surface. For ferrule. 2. The ferrule for a single-core optical connector according to claim 1, wherein a rear end portion of the cylindrical sleeve is also embedded in the plastic resin.