JP2001108867A - Ferrule for numerous fiber optical connector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To secure the dimensional precision and to suppress the eccentricity of a fiber hole. SOLUTION: Recessed parts 21 are formed on the upper and lower surfaces of the middle part in the width direction of the ferrule main body part 12 of a ferrule 11 to make the wall of this part thin. Also, corners of the outside part of a guide pin hole forming part 23 (the peripheral part of a guide pin hole 16) are cut off to form the guide pin hole forming part 23 into an octagonal shape. The whole uneven wall parts of the ferrule 11 are reduced by forming a recessed part 22 and notches 13b in a flange part 13 or the like. The thick or uneven wall part is reduced as the whole shapes of the ferrule 11. Thus, ununiformity of heat shrinkage of molten resin is restrained and distortion is reduced in plastic molding.

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 multi-fiber optical connector of a fitting pin alignment type, wherein guide pins are formed on both right and left sides of a plurality of optical fiber holes arranged side by side.

[0002]

2. Description of the Related Art A multi-fiber optical connector of a mating pin alignment method is commonly called an MT optical connector, and a ferrule used for this connector is defined in JIS C 5981 as an F12 type optical fiber connector. FIG. 4 shows a ferrule 1 of this type of conventional optical connector (MT optical connector). This ferrule 1 is a slightly thin square ferrule body 2
Has a contour shape with a square flange 3 on the base end side of
It has a structure in which guide pin holes 6 are provided on the left and right sides of four optical fiber holes 5 in a horizontal row opened to the connection end face 4. Reference numeral 7 denotes an opening for injecting an adhesive. This kind of ferrule 1
In general, for example, epoxy resin or the like is used as a molding material, and is molded by injection molding, transfer molding, or the like.

[0003]

By the way, in the MT optical connector, in order to enable connection with a small connection loss,
The shape and dimensions of the ferrule 1 require high accuracy and shape stability. In particular, high accuracy for the position of each optical fiber hole with reference to the diameter of the optical fiber hole, the diameter of the guide pin hole, the distance between the center of the left and right guide pin holes, and the midpoint of the line connecting the centers of the left and right guide pin holes. Is required. If the required precision is not satisfied in plastic molding of ferrules, the ferrules must be discarded as defective products, and the production yield decreases. However, there has been a problem that as the number of fiber holes increases, the ferrule warps and the position of the fiber hole becomes eccentric. The cause of the defective shape and shape in plastic molding includes unevenness in heat shrinkage when the molding material injected into the mold at about 200 ° C. is cooled to room temperature. The conventional ferrule 1 shown in FIG. In the molding of, it was not always possible to stably obtain high-precision shapes and dimensions, and the production yield was not sufficiently high.

[0004]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention is directed to a plastic multi-core optical connector having guide pin holes formed on both left and right sides of a plurality of optical fiber holes arranged side by side. The ferrule is characterized in that an intermediate portion between the left and right guide pin holes is vertically symmetrically thin.

According to a second aspect of the present invention, in the ferrule for a multi-core optical connector according to the first aspect, the outer portions of the left and right guide pin hole forming portions each have a polygonal or circular cross-sectional shape.

[0006]

FIG. 1 is a block diagram showing an embodiment of the present invention.
This will be described with reference to FIG. FIG. 1 is a perspective view of a ferrule 11 of an optical connector according to an embodiment of the present invention, and FIG. 2 is a sectional view. This ferrule 11 is used as a multi-fiber optical connector of a fitting pin alignment method. The ferrule 11 has a flange portion 13 on the base end side of a slightly thin ferrule main body portion 12, and a plurality of side-by-side ferrules opening on a connection end surface 14. Optical fiber hole 15
Are provided with guide pin holes 16 on both left and right sides. The inside of the ferrule 11 is as shown in FIG. 2, in which an optical fiber core wire insertion opening 17, an optical fiber guide groove 18, and an adhesive injection window 19 are formed. Reference numeral 20 denotes a rubber boot for protecting the insertion opening of the inserted optical fiber. The illustrated example is a ferrule for a four-core optical fiber ribbon, and is provided with four optical fiber holes 15 in a horizontal row.

In the present invention, the widthwise intermediate portion of the ferrule 11 (particularly, the connection end surface side) is made thin. In this embodiment, the recesses 21 are formed symmetrically on the upper and lower surfaces of the ferrule main body 12 in the vicinity of the connection end surface 14 between the left and right guide pin holes 16 so as to be thin. Also, recesses 22 are formed on the upper and lower surfaces of the flange portion 13 to make it slightly thinner. In addition, the outer portions of the left and right guide pin hole forming portions 23 (that is, the peripheral portions of the guide pin holes 16) 23 of the ferrule main body portion 12 are substantially octagonal in the illustrated example. The guide pin hole forming portion 23 is formed in the above-mentioned substantially octagonal shape by tapering both side portions of the recess 21 and chamfering ridges at both left and right ends of the ferrule main body 2 of the conventional ferrule 1 of FIG. are doing.

[0008] The collar portion 13 is provided with the ferrule main body portion 12.
Only the shoulder portion 13a adjacent to and has a predetermined width, and the other portion is notched (the notch portion is indicated by 13b) to reduce the width.

As a molding material of the ferrule 11, for example, epoxy resin or PPS (polyphenylene sulfide) is used, and as a molding method, transfer molding, injection molding, or the like is employed. FIG. 3 shows an example of a mold 30 for molding the ferrule 11. In the figure,
31 is an upper mold, 32 is a lower mold, and 33 is a middle mold. In the illustrated example, the lower mold 32 is fixed, and the upper mold 31 is vertically movable. The middle mold 33 is slidable in a horizontal direction indicated by an arrow at a height position at which the middle mold 33 is fitted to the lower mold 32. The middle mold 33 includes a core part 33a forming the optical fiber core wire insertion opening 17, the optical fiber guide groove 18, the adhesive injection window 19, etc. of the ferrule 11, a pin 33b forming the optical fiber hole 15, and a guide pin hole 16. The pins 33c to be formed are integrally provided. Adhesive injection window 19
Are not shown in the figure, but the core part 3
There is a protrusion on the lower surface side of 3a. The upper mold 31 and the lower mold 32 have concave portions 31a and 32a (31a not shown) that form a cavity between the upper mold 31 and the middle mold 33. Lower mold 3
In the second recess 32a, a protrusion 32f forming the recess 21 of the ferrule 11, a protrusion 32g forming the recess 22,
It has an inclined portion 32h and the like forming the guide pin hole forming portion 23. The lower mold 32 has a pin 33b for an optical fiber hole.
V-groove 32d for positioning and accommodating the distal end of the V-groove 3 for positioning and accommodating the distal end of the pin 33c for the guide pin hole.
2e is formed. In the illustrated mold 30, the upper mold 31
Is provided with a gate 35 for injecting a resin. Note that FIG.
When the molded article formed by the mold 30 is turned upside down, the state shown in FIG. 1 is obtained.

When a molten resin is injected from the gate 35 into the mold 30 and cured, the upper mold 31 is opened, the middle mold 33 is retracted, the molded product is taken out, and the gate of the molded product is cut by a gate cutter. , FIG. 1 and FIG. 2 are obtained.

In general, one of the causes of defective shape and dimensions in plastic molding is that 200
There is uneven heat shrinkage when the molding material of about ° C is cooled to room temperature. That is, the cooling rate of the molten resin is slower and the heat shrinkage is slower in the thick or uneven portion (refers to a portion where the volume is more unevenly distributed than the surrounding portion) than in the thin portion. As a result, distortion (including warpage) occurs in the molded product. However, in the case of the ferrule 1, the ferrule body 12 and the flange 13 are partially thin (the recess 2).
1 and 22), and the thickness or uneven thickness portion is reduced as a whole.
In comparison with the molding of the above, the unevenness of the cooling rate of the molten resin and the unevenness of the heat shrinkage associated therewith are small, and the occurrence of distortion is small. Further, since a small amount of the resin used is a good condition for uniform molding, this point is also advantageous for suppressing distortion. Further, in this embodiment, since the outer surface of the guide pin hole forming portion 23 is not a rectangular shape but an octagonal shape, the uneven thickness of this portion is eliminated or the angular portion is eliminated, so that the heat shrinkage is prevented. Non-uniformity is suppressed and distortion is reduced. In the case of a conventional rectangular shape, stress concentration due to injection pressure (or pressure of resin injection) is likely to occur at a right angle portion, and distortion is likely to occur. However, since the angle is obtuse, distortion also occurs at this point. Can be suppressed. In addition, the collar 13
Also at the point where the notch 13b is formed, unevenness in heat shrinkage is suppressed, and distortion is reduced.

The outer portion of the guide pin hole forming portion 23 is not limited to an octagonal shape, but may be a hexagonal shape, a more polygonal shape,
Alternatively, the shape may be circular. The molding material to be used is not particularly limited, and a thermosetting resin and a thermoplastic resin that can be used as a ferrule of an optical connector can be used.

Although the above embodiment is an example of a 4-core optical connector, the number of cores is not limited as long as it is a 2-core, 8-core, 16-core, 24-core or other multi-core optical connector. In addition, although the optical fiber holes are usually arranged in a horizontal row, a two-dimensional array in which the optical fiber holes are arranged in two or three stages is also conceivable.

[0014]

According to the present invention, the thickness of the ferrule in the width direction is reduced at the middle portion in the width direction, so that the ferrule has a reduced thickness or uneven thickness as a whole shape. Uniformity was suppressed and distortion could be reduced. As a result, the dimensional accuracy was secured, and the eccentricity of the fiber hole could be suppressed.

According to the second aspect of the present invention, the right and left guide pin hole forming portions of the ferrule have no right-angled portions at the outer portions and become obtuse or curved surfaces, so that uneven thickness portions are reduced and distortion is reduced. Also, the occurrence of strain is suppressed at the point where stress concentration is eliminated. As a result, the dimensional accuracy was secured, and the eccentricity of the multi-core optical fiber hole could be suppressed.
Furthermore, according to the present invention, the amount of resin of the ferrule (particularly, the amount of resin on the connection end surface side which affects the positional accuracy of the fiber hole)
As a result, the occurrence of distortion generated during resin curing can be reduced as much as possible, and the eccentricity of the fiber hole can be suppressed.

[Brief description of the drawings]

FIG. 1 is a perspective view of a ferrule for a multi-core optical connector according to an embodiment of the present invention.

FIG. 2 is a longitudinal sectional view of FIG.

FIG. 3 is an exploded perspective view of a mold for molding the ferrule for a multi-core optical connector.

FIG. 4 is a perspective view of a conventional ferrule for a multi-core optical connector.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Ferrule (ferrule for multi-core optical connectors) 12 Ferrule main body part 13 Collar part 13a Shoulder part 13b Notch part 14 Connection end face 15 Optical fiber hole 16 Guide pin hole 17 Optical fiber core wire insertion opening 21 Concave part (thin part) 22 recess (thin part) 23 guide pin hole forming part 30 die 31 upper die 32 lower die 33 middle die

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H036 JA02 QA12 QA18 QA20 QA49 4F202 AA34 AA39 AH34 CA11 CB01 CK54 4F206 AA34 AA39 AH34 JA07 JQ81

Claims (2)

[Claims] 1. A ferrule for a multi-fiber optical connector of a fitting pin alignment type, wherein guide pin holes are formed on both left and right sides of a plurality of optical fiber holes arranged side by side, wherein an intermediate portion between the left and right guide pin holes is provided. For ferrules for multi-core optical connectors, characterized in that the part is made thin vertically and symmetrically. 2. The ferrule for a multi-fiber optical connector according to claim 1, wherein the outer portions of the left and right guide pin hole forming portions each have a polygonal or circular cross-sectional shape.