Fiber optic connector and an associated pin retainer

Details Fiber optic connector and an associated pin retainer Fiber optic connector and an associated pin retainer

2001-06-11

2003-12-30

Lee, John D. (Department: 2874)

Optical waveguides

With disengagable mechanical connector

Optical fiber/optical fiber cable termination structure

C385S053000, C385S055000, C385S076000, C385S071000, C385S072000

Reexamination Certificate

active

06669377

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates generally to fiber optic connectors and associated guide pin retention mechanisms and, more particularly, to a fiber optic connector having a ferrule that is compatible with conventional connectors and a variety of ferrules, as well as an improved guide pin retention mechanism that permits guide pins to be inserted into the fiber optic connector following assembly of the fiber optic connector and the polishing of the front face of the ferrule.
BACKGROUND OF THE INVENTION
Multi-fiber cables or ribbons are being increasingly employed in a wide variety of applications. As such, several standard multi-fiber connectors have been developed and are commonly utilized. Perhaps the most common multi-fiber connector is the MT-RJ connector having a rectangularly-shaped mini-MT ferrule that was developed by Nippon Telegraph & Telephone Corporation of Tokyo, Japan. An MT-RJ connector is commonly assembled utilizing a heat cure epoxy process. In this regard, epoxy is introduced via a window defined by the mini MT ferrule into the bores defined by the MT ferrule through which the end portions of the optical fibers extend. The epoxy is heat cured to secure the end portions of the optical fibers within the mini MT ferrule. The front face of the ferrule is then polished, and the remainder of the components of the MT-RJ connector are assembled about the ferrule.
With respect to the assembly of the other components of the MT-RJ connector, the mini-MT ferrule is mounted within a connector housing such that the front face of the ferrule is exposed. In this regard, the mini-MT ferrule includes a lengthwise extending shank and an enlarged shoulder portion proximate the rearward end of the shank. The shoulder portion is larger in lateral cross-section than the shank, thereby defining a shoulder. Upon insertion of the mini-MT ferrule into the connector housing during the assembly of an MT-RJ connector, the shoulder of the mini-MT ferrule is engaged by an inwardly projecting ledge within the connector housing such that the front face of the ferrule extends outwardly beyond the connector housing while the enlarged shoulder portion of the ferrule is retained within the connector housing. Thus, a mini-MT ferrule must include an enlarged shoulder portion to define a shoulder for engaging the connector housing.
Another common multi-fiber connector is the MT-RJ UniCam® connector having a modified MT ferrule referred to as the E-ferrule. The UniCam® connector can be mounted upon one or more optical fibers by means of a mechanical splice that permits the UniCam® connector to be field installable. In this regard, fiber stubs are typically mounted within respective bores defined by the E-ferrule. The fiber stubs are secured within the ferrule by means of an epoxy, and the front face of the ferrule is then polished. While the mounting of the E-ferrule upon one or more fiber stubs and the polishing of the front face of the ferrule are typically performed at the factory, the UniCam® connector can be spliced onto one or more field fibers in the field. In this regard, the UniCam® connector also includes a splice component holder that engages the rearward end of the ferrule. The splice component holder defines a lengthwise extending passageway that is sized and shaped to receive a pair of splice components. The splice components define lengthwise extending grooves for receiving end portions of the optical fiber stubs and the field fibers. In particular, the fiber stubs upon which the ferrule is mounted extend into the grooves defined by the splice components from one end, while the field fibers are inserted into the grooves defined by the splice components from the other end. By rotating a cam member relative to the splice component holder, the splice components are forced together, thereby mechanically splicing the field fibers and the fiber stubs. See, for example, U.S. Pat. No. 6,173,097 by Rodney A. Throckmorton, et al. entitled Field Installable Multifiber Connector, the contents of which are incorporated herein by reference.
Since the E-ferrule must be engaged by the splice component holder in order to ensure alignment of the fiber stubs and the field fibers, the E-ferrule generally has a different design than the MT ferrule utilized by MT-RJ connectors. Rather than an enlarged shoulder, the E-ferrule has a reduced shoulder portion. As such, the portion of the passageway defined by the splice component holder proximate its forward end is sized and shaped to snugly receive the rearward end of the E-ferrule such that the ferrule and the splice component holder are maintained in an aligned relationship.
It would be desirable to provide a common ferrule that is compatible with and capable of replacing both the mini-MT ferrule and the E-ferrule. By providing a common ferrule, the number of different ferrules that would have to be manufactured would be substantially reduced, thereby streamlining manufacturing operations. In addition, the number of different ferrules that would have to be maintained in inventory and carried by field technicians would also be advantageously reduced. Due to the substantial differences in functionality and design of the various ferrules, however, the design of a universal ferrule has been heretofore unsuccessful.
In addition to the MT-RJ connector and the MT-RJ Unicam® connector, another common multi-fiber connector is the MTP or MPO connector (hereinafter referenced as the MTP connector). The MTP connector has a larger version of the MT ferrule than the MT-RJ connector and can therefore be mounted upon the end portions of a larger number of optical fibers than the MT-RJ connector. As with the MT-RJ connector, however, an MTP connector is commonly assembled by a heat cure epoxy process. In this regard, epoxy is introduced via a window defined by the MT ferrule into the bores defined by the MT ferrule through which the end portions of the optical fibers extend. The epoxy is heat cured to secure the end portions of the optical fibers within the MT ferrule. The front face of the ferrule is then polished, and the remainder of the components of the MTP connector are assembled about the ferrule.
Regardless of the type of multi-fiber connector, the multi-fiber connector should be capable of receiving guide pins in order to facilitate the alignment of the multi-fiber connector with another connector or with an interface device. The alignment of the connector, in turn, permits alignment of the optical fibers upon which the connector is mounted. Depending upon the type of multi-fiber connector, different guide pin retention mechanisms have been developed.
With respect to the MT-RJ and MTP connectors, for example, two different configurations have been developed, namely, a male configuration that includes a pair of guide pins extending outwardly beyond the front face of the MT ferrule and a female configuration that does not include guide pins but that defines a pair of guide pin holes. A pair of these connectors are therefore mated by inserting the guide pins of a male connector into the guide pin holes of a female connector.
In order to retain the guide pins in the male configuration of the MT-RJ or MTP connector, each connector generally includes a pin keeper. During the assembly process, the guide pins are engaged by the pin keeper prior to the insertion of the guide pins into a ferrule. The pin keeper is then positioned immediately rearward of the MT ferrule such that the guide pins inserted through the guide pin holes defined by the MT ferrule from the rear of the MT ferrule so as to protrude outwardly beyond the front face of the MT ferrule. Thus, the guide pins of the male configuration of an MT-RJ or MTP connector must be inserted during the factory assembly process and cannot be inserted in the field once the remainder of the connector has been assembled. As a result, the female configuration of an MT-RJ or MTP connector cannot be converted to a male configuration in the field by merely inserting guide pins through the guide pins holes de

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