JPH0564804U - Ferrule for optical fiber - Google Patents

Abstract

(57) [Summary] [Object] To provide a ferrule for an optical fiber that can easily and reliably hold an optical fiber strand and that is hard to break. [Structure] The insertion hole of the sleeve has a small diameter portion having an inner diameter substantially equal to the outer diameter thereof for positioning the most distal end portion of the element wire, and extends coaxially from the small diameter portion toward the base end side and has a small diameter. By having a large diameter part with a slightly larger inner diameter than the part, this large diameter part serves as an insertion guide, and the part with no play for positioning the wire is comparatively shortened and friction is reduced. Can be inserted. Further, even after the insertion, the stress concentrated on a part of the wire can be dispersed in the large diameter portion. Therefore, the optical fiber can be easily and surely held in the ferrule without being cut, and the assembling workability is improved and the reliability is also improved.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a ferrule used for an optical fiber connector for holding an end portion of an optical fiber, and in particular, a sleeve made of a ceramic material in which an element wire of the optical fiber is inserted and a base end side of the sleeve. And a ferrule for an optical fiber having a flange.

[0002]

[Prior Art]

 In the optical fiber connector for connecting the end of the optical fiber to each device, etc., the primary coating from the core of the optical fiber, the ceramic sleeve through which the bare wire exposed by stripping the jacket is inserted, and this sleeve The ferrule has a flange provided on the base end side of the connector and a flange that is integral with this flange and that holds the base end side core wire part of the part that is inserted into the sleeve. There is.

The sleeves include those made of a metal material such as stainless steel and those made of a ceramic material such as zirconia. For example, a sleeve made of a ceramic material has an advantage of being less affected by heat and has been conventionally used. Widely used.

In the case of the sleeve made of this ceramic material, the through hole provided in the sleeve has an inner diameter substantially equal to the outer diameter of the optical fiber element wire, and the exposed element wire of the optical fiber is It is designed to be inserted from the base end side.

However, there has been a problem that the wire is easily cracked at the insertion base end portion of the sleeve, especially during assembly, and the wire is cracked. It is considered that this is because there is almost no play between the wire and the through hole of the sleeve, so that friction between them becomes large and stress concentrates on the wire at the insertion base end.

[0006]

SUMMARY OF THE INVENTION In view of the above problems of the prior art, the main object of the present invention is to provide an optical fiber that can easily and surely hold an optical fiber wire and that is hard to break. Providing fiber ferrules.

[0007]

[Means for Solving the Problems]

 According to the present invention, the above-mentioned object has a sleeve in which an element wire of the optical fiber is inserted to hold an end portion of the optical fiber, and a flange provided on a proximal end side of the sleeve. The sleeve is a ferrule made of a ceramic material, and the insertion hole for the wire of the sleeve has a small-diameter portion having an inner diameter substantially equal to the outer diameter of the wire to support the distal end of the wire. This is achieved by providing a ferrule for an optical fiber, which is coaxially extended from the small diameter portion toward the base end side and has a large diameter portion having an inner diameter slightly larger than the small diameter portion. ..

[0008]

[Action]

 With this configuration, the large diameter portion serves as a guide for inserting the wire when the wire is inserted, and the portion having no play for positioning the wire is comparatively short and friction is reduced. Further, even after the wire is inserted, the stress concentrated on a part of the wire can be dispersed in the large diameter portion.

[0009]

【Example】

 Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a vertical cross-sectional view of an optical fiber connector 1 provided at an end of an optical fiber cable 2 to which the present invention is applied.

The optical fiber cable 2 includes a core fiber 6 formed of a thermoplastic resin jacket 5 provided on the center optical fiber element wire 3 and a primary coating 4 made of silicon resin on the outer periphery thereof. It has a reinforcing fiber 7 provided on the outer circumference of the core wire 6 and a vinyl coating 8 on the outermost circumference.

As also shown in FIG. 2, the tip of the strand 3 in the optical fiber cable 2 is held by the ferrule 10. This ferrule 10 is received inside a generally rectangular plug frame 11, and a sleeve 13 on the tip side thereof projects to the tip side of the optical fiber connector 1, that is, on the right side in FIG. A stop ring 15 is provided on the base end side of the ferrule 10 located in the inner hole 11a of the plug frame 11, and the compression coil spring 14 is received between the plug frame 11 and the flange 16 of the ferrule 10. The ferrule 10 shrinks when force is applied. Here, an outward flange 16 is provided at the base end portion of the ferrule 10, and the flange is brought into contact with the inward flange 17 of the plug frame 11 to define the protruding range of the ferrule 10. Further, an axial groove 16a is provided in a part of the outward flange 16, and the groove engages with a key portion 18 provided in the inner hole 11a of the plug frame 11, whereby the plug frame of the ferrule 10 is plugged. A rotation stop for the arm 11 is provided.

An outer cover 19 is fitted around the outer periphery of the plug frame 11 and the stop ring 15. A groove 20 is provided at an intermediate position of the outer cover 19, and the groove 20 abuts on a projecting piece 21 provided at an intermediate portion of the outer periphery of the plug frame 11, whereby the optical fiber connector 1 tip side of the outer cover 19 is provided. The moving range to is defined.

A caulking ring 23 including a small diameter portion 26 and a large diameter portion 27 is screwed and held at the base end portion of the stop ring 15. A hood 25 made of synthetic rubber is wrapped around the caulking ring 23. A reinforcing fiber 7 at the tip of the optical fiber cable 2 is held between the male screw portion of the outer periphery of the base end portion of the stop ring 15 and the female screw portion of the inner diameter of the large diameter portion 27 of the caulking ring 23.

As shown in FIG. 2, the ferrule 10 is a flange metal fitting made of stainless steel having a sleeve 13 made of zirconia as a ceramic material and the outward flange 16 having a base end portion press-fitted therein. It is composed of 12 and. The insertion hole of the sleeve 13 coaxially extends from the small diameter portion 13a toward the base end side, and a small diameter portion 13a having an inner diameter substantially equal to the outer diameter of the strand 3 for positioning the tip end portion of the wire 3. And a large diameter portion 13b having an inner diameter slightly larger than that of the small diameter portion 13a.

Here, the sleeve is made of a ceramic material, and therefore it is fired after being injection-molded, but a mold pin is used to secure an insertion hole for a wire during injection molding. Therefore, if a through hole with an inner diameter that is approximately equal to the outer diameter of the strand is provided over the entire length as in the past, a relatively long and thin pin must be used, and it is difficult to ensure its rigidity. In this embodiment, most of the insertion hole is formed of the large diameter portion 13b, so that the thin portion of the die pin can be shortened and its rigidity can be improved.

The large-diameter portion 13b is filled with a two-liquid adhesive 32 made of a relatively soft epoxy resin.

Next, a procedure for assembling the optical fiber connector 1 will be described. First, the vinyl coating 8 at the tip of the optical fiber cable 2 is cut off by a predetermined length. Then, the jacket 5 and the primary coating 4 are cut off from the intermediate portion of the portion of the core wire 6 exposed from the cable 2. Next, the caulking ring 23, the stop ring 15 and the compression coil spring 14 are fitted to the core wire 6, the core wire is inserted into the inner hole of the flange fitting 12 of the ferrule 10, and the optical fiber strand 3 is inserted into the sleeve 13. The large diameter portion 13b of the insertion hole is inserted into the small diameter portion 13a. At this time, the adhesive 32 is also filled at the same time to bond the optical fiber element wire 3 to the sleeve 13.

Here, as described above, the through hole of the sleeve 13 includes the small diameter portion 13a on the front end side and the large diameter portion 13b having an inner diameter larger than that of the small diameter portion 13a, so that the wire 3 is large. When inserting into the small diameter portion 13a via the diameter portion 13b, the large diameter portion 13b serves as an insertion guide, and there is no concern that stress concentrates on a part of the wire 3. Further, the small-diameter portion 13a is shorter than that of the conventional sleeve, and the friction is reduced, so that the strand 3 can be smoothly inserted into the through hole of the sleeve 13. In addition, since the adhesive 32 is relatively soft, the stress is not dispersed in the large diameter portion 13b even after the insertion, and the stress is not concentrated on a part of the wire.

In order to assemble the ferrule assembly thus processed into the optical fiber connector 1, first, the ferrule 10 is inserted from the base end of the inner hole 11a of the plug frame 11, and the sleeve 13 is projected. Next, the compression coil spring 14 and the stop ring 15 are inserted into and engaged with the inner hole 11a. Then, the reinforcing fiber 7 around the outer circumference of the core wire 6 is cut into a proper length and is also sandwiched between the stop ring 15 and the large diameter portion 27 of the caulking ring 23. Here, by sandwiching the reinforcing fiber 7 between the ring 31 and the base end of the plug frame 11, there is no concern that the strand 3 will be affected even if the optical fiber cable 2 is pulled in the axial direction.

Finally, the hood 25 is wrapped, the outer cover 19 is fitted onto the frame 11 from the front end side of the plug frame 11, and they are engaged with each other to complete the optical fiber connector 1.

[0022]

[Effect of the device]

 As is clear from the above description, according to the optical fiber ferrule of the present invention, the insertion hole of the sleeve has a small-diameter portion having an inner diameter substantially equal to the outer diameter of the element wire in order to position the distal end portion of the element wire. By extending coaxially from the small diameter part toward the base end side and having a large diameter part with an inner diameter slightly larger than the small diameter part, this large diameter part serves as an insertion guide and also a play for positioning the wire. The part without a wire is comparatively short and friction is reduced, so that the wire can be inserted smoothly. Also, even after the insertion, the stress concentrated in a part of the wire can be dispersed in the large diameter part. Therefore, the optical fiber can be easily and surely held in the ferrule without being cut, and the assembling workability is improved and the reliability is also improved.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of an optical fiber connector to which the present invention is applied.

FIG. 2 is an enlarged sectional view showing only a main part of FIG.

[Explanation of symbols]

 1 Optical fiber connector 2 Optical fiber cable 3 Optical fiber wire 4 Primary coating 5 Jacket 6 Core wire 7 Reinforcing fiber 8 Vinyl coating 10 Ferrule 11 Plug frame 11a Inner hole 12 Flange metal fitting 13 Sleeve 13a Small diameter part 13b Large diameter part 14 Compression Coil spring 15 Stop ring 16 Outward flange 16a Axial groove 17 Inward flange 18 Key portion 19 Outer cover 20 Groove 21 Projection piece 23 Caulking ring 25 Hood 26 Small diameter portion 27 Large diameter portion 32 Adhesive

Claims (3)

[Scope of utility model registration request] 1. A sleeve having a strand through which the optical fiber is inserted to hold the end of the optical fiber, and a flange provided at the base end side of the sleeve, the sleeve being made of a ceramic material. A ferrule, wherein an insertion hole for the strand of wire of the sleeve has a small diameter portion having an inner diameter substantially equal to the outer diameter of the strand to support the distal end portion of the strand, and coaxial with the small diameter portion toward the base end side. And a large diameter part having an inner diameter slightly larger than the small diameter part. 2. The ferrule for an optical fiber according to claim 1, wherein the element wire is bonded with an adhesive at the large diameter portion. 3. The ferrule for an optical fiber according to claim 1, wherein the sleeve and the flange are integrally formed of the ceramic material.