Optical waveguides – With disengagable mechanical connector – Structure surrounding optical fiber-to-fiber connection
Reexamination Certificate
2000-04-19
2001-09-11
Lee, John D. (Department: 2874)
Optical waveguides
With disengagable mechanical connector
Structure surrounding optical fiber-to-fiber connection
C249S064000, C425S117000
Reexamination Certificate
active
06287017
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an optical connector ferrule used to connect end faces of optical fibers, a method of manufacturing the connector ferrule, and an optical connector using the connector ferrule.
2. Related Background Art
As a connector used for a connection of a plurality of optical fibers, an optical connector of the type standardized by JIS C 5981 is generally known. An optical connector of this type is manufactured by using a mold like the one disclosed in Japanese Patent Laid-Open No. 8-179161. As shown in
FIGS. 17 and 18
, an optical connector C is of a type designed to position and fix optical fibers with a connector ferrule
1
. As shown in
FIG. 17
, this connector ferrule
1
is mounted on the end portion of a fiber optic ribbon cable
2
. A pair of guide-pin holes
11
are formed in a mating end face
10
to be connected with another optical connector C. Guide pins
3
for positioning and fixing the mating end faces of the two connectors are inserted in the guide-pin holes
11
. These guide-pin holes
11
extend through the connector ferrule I from the mating end face
10
to the reverse end. The end portions of fiber positioning holes
13
for positioning the optical fibers in the fiber optic ribbon cable
2
are also formed in the mating end face
10
. The optical connectors C described above are mutually positioned by inserting the common guide pins
3
into the guide-pin holes
11
and coupled to each other, as shown in FIG.
18
. The coupled state of the two connectors is held by a clamp spring
5
.
SUMMARY OF THE INVENTION
Optical connectors of this type are used for optical connection in a place where an optical communication line needs to be branched or switched. To switch connection, optical connectors must be detached/attached. It is required for such optical connectors that connection loss variations be small even if the connectors are repeatedly detached/attached.
It is, therefore, an object of the present invention to provide an optical connector which causes little connection loss variations even with repetitive detachment/attachment, a connector ferrule for the optical connector, and a method of manufacturing the optical connector ferrule.
In order to achieve the above object, an optical connector ferrule according to the present invention comprises: a ferrule body made from a resin by molding and having a mating end face, at least one fiber receiving hole and a pair of guide-pin holes, each of them extending from the mating end face toward the other end of the ferrule body, wherein the diameter of the guide-pin holes gradually increases toward the mating end face at a predetermined portion near the mating end face.
According to the optical connector using this connector ferrule, when a guide pin is to be inserted into the guide-pin hole from the mating end side, since the diameter of the guide-pin hole gradually increases toward the mating end, the guide pin can be easily and smoothly inserted into the guide-pin hole. This can suppress damage to the connector ferrule or wear thereof by the guide pin, and hence can realize an optical connector which can maintain good transmission characteristics even if the connector is repeatedly detached/attached.
Preferably, each guide-pin hole has a cylindrical region between the enlarged region and the mating end face. A cylindrical region causes a desired enlarged region to be reliably formed in a resin molding process. Each extending length of the cylindrical region is preferably from 2 &mgr;m to 50 &mgr;m.
The enlarged region of each guide-pin hole may have a truncated cone shape, as defined by its wall, having an apical angle from 30° to 70°. The wall surface of the enlarged region of each guide-pin hole may be formed by a curved surface toward an inside of the guide-pin hole. The enlarged region of each guide-pin hole is preferably located within a range of 0.1 mm to 1.0 mm from the mating end.
When an enlarged region is formed in this manner, the formation of the enlarged region itself is facilitated, and a guide pin can be easily and reliably inserted into a guide-pin hole. This can reliably suppress damage to the connector ferrule or wear thereof by the guide pins, and easily realize an optical connector which can always maintain good transmission characteristics even with repetitive detachment/attachment.
An optical connector according to the present invention is an optical connector using these optical connector ferrules. This optical connector is comprised of a pair of optical fiber sets each including at least one optical fiber in equal numbers; a pair of optical connector ferrules each defined above, positioning and fixing the respective optical fiber set; and a pair of guide pins which are inserted into the guide-pin holes in the optical connector ferrules to butt-joint the mating end faces of the optical connector ferrules to each other.
According to this optical connector, since the guide pins can be easily and smoothly inserted, damage to the connector ferrules or wear thereof by the guide pins can be suppressed, and good transmission characteristics can always be maintained even with repetitive detachment/attachment.
A method of manufacturing an optical connector ferrule according to the present invention comprises the steps of (1) opposing an mating end-side core and a fiber-side core to each other in a mold and fastening them together so as to form a mold, the mating end-side core having a pair of guide-pin hole molding pins and a predetermined number of needle-like fiber receiving hole molding pins, each of the guide-pin hole molding pins having a base portion where the diameter increases toward the core body and said fiber-side core having a protruding portion for forming an opening of a ferrule; (2) filling the mold cavity with a resin; (3) forming a ferrule body having a pair of guide-pin holes and a predetermined number of fiber positioning holes by setting the resin; (4) sliding the mating end-side core and the fiber-side core in a direction in which the cores are to be separated from each other; and (5) taking out the ferrule body from the mold.
Alternatively, instead of step (
1
), the method of manufacturing the optical connector ferrule according to the present invention may have the step of (la) opposing an mating end-side core and a fiber-side core to each other in a mold and fastening them together so as to form a mold, the mating end-side core having a pair of guide-pin hole molding pins each having a base portion where the diameter increases toward the core body and said fiber-side core having a protruding portion for forming an opening of a ferrule.
According to these manufacturing methods, when guide-pin holes are formed in an optical ferrule body, enlarged regions can be easily and reliably formed on the mating end.
In addition, if the fiber-side core is further comprised of at least one pipe-like molding portion each for inserting the guide-pin hole molding pin or the fiber positioning hole pin on the mating end-side core then the mating end-side core and fiber-side core can be reliably fastened to each other. This improves operability in a connector ferrule molding process.
The present invention will be more fully understood from the detailed description given hereinbelow and the accompanying drawings, which are given by way of illustration only and are not to be considered as limiting the present invention.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will be apparent to those skilled in the art from this detailed description.
REFERENCES:
patent: 5778126 (1998-07-01), Saitoh
patent: 5780079 (1998-07-01), Lee
patent: 5786002 (1998-07-01), Dean et al.
patent: 581
Kakii Toshiaki
Katsura Hiroshi
Sakurai Wataru
Shibata Masahiro
Lee John D.
McDermott & Will & Emery
Song Sarah N
Sumitomo Electric Industries Ltd.
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