Abstract:
The present invention provides a fiber optic connector and a method for installing a fiber optic connector including a barrel assembly disposed within a housing. The barrel assembly includes a barrel being formed of deformable material and having a barrel body and a barrel extension extending from an end of the barrel body. An opposing end of the barrel body supports a ferrule having a pre-polished fiber stub disposed therein. An insert is disposed within the barrel, the insert being deformable and is arranged and configured to receive at least one fiber. An extender cap engages a portion of the housing fixing the barrel assembly within the housing. The housing includes at least one aperture disposed in a side portion for accessing the barrel assembly. 
     In one aspect of the invention a method for installing a fiber optic connector is provided including the steps of, first, forming a barrel assembly. The barrel assembly is then placed in the housing and an extender cap disposed on a protruding portion of the barrel to fix the barrel assembly in the housing. Finally, a fiber is inserted into the barrel until the fiber contacts the fiber stub and the fiber is crimped into the insert.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates generally to a connector for fiber optic cable, and, more particularly, to a fiber optic connector that can be readily installed in the field without the need for epoxy or anaerobic adhesives. 
     Optical fiber connectors and splices are an essential part of optical fiber communications systems. Connectors may be used to join lengths of optical fiber into longer lengths, or to connect optical fiber to active devices such as radiation sources, detectors, repeaters, or to passive devices such as switches or attenuators. 
     Many prior art connectors use adhesives or epoxies in securing connector components. For example, a typical connector includes a ferrule piece rigidly attached to a connector body. Adhesive is injected into a longitudinal bore of the ferrule. A cable is received into the connector body with the stripped fiber projecting along the longitudinal bore of the ferrule and is cemented therein by the adhesive. This adhesive typically must be heat cured. As such, heat curing ovens are needed in the field where the connectors are being installed and a source of power for the ovens must be available. The adhesive wicks and adheres to the fiber, the ferrule, the connector body, and other connector parts to permanently secure the connector components to one another. 
     Other known connectors include quick-connect type designs having a fiber stub disposed within the connector and a grooved insert for splicing fiber ends. One known design includes a split cylinder with an expanded metal split sleeve which is spread open by a pair of wires. Removal of the wires collapses the sleeve over two non-compliant inserts to capture the fibers. Another approach uses a cam ring to compress two non-compliant inserts. While these approaches seem to work well with larger connectors, such as the ST and SC, due to the physical size of the internal components, the design does not appear to be compatible with smaller connectors, such as the LC. 
     There is a growing demand for a fiber optic connector of smaller size that is simple to install or assemble in a field setting. In particular, where single connectors are installed such as at a wall outlet, there is a growing resistance to the use of epoxies that require special heat-curing ovens to facilitate solidification, and, in general, to the use of chemicals such as anaerobic adhesives. 
     Accordingly, what is sought is a fiber optic connector that can be easily installed or assembled without the use of epoxies, adhesives, or polishing. Thereby, eliminating the time and tools needed to heat cure adhesives and polish fibers in the field. 
     SUMMARY OF THE INVENTION 
     Certain advantages and novel features of the invention will be set forth in the description that follows and will become apparent to those skilled in the art upon examination of the following or may be learned with the practice of the invention. 
     The present invention is generally directed to a fiber optic connector that can be installed in the field without the use of any adhesive or epoxy, or the need to polish the fiber in the field. The connector includes a housing with a barrel, having a malleable portion, disposed therein. The barrel is formed as a unitary piece having two portions, a barrel body and a barrel extension, axially aligned with one another. A ferrule supporting a fiber stub is disposed on an end of the barrel body opposing the barrel extension such that the fiber stub extends into the barrel body. A two-part insert, comprising a compliant portion and a support portion, is arranged and configured within the barrel body to receive the fiber stub supported by the ferrule and a field inserted fiber. The support portion of the insert includes a groove to position and align the fibers. The compliant portion of the insert acts as a load transfer member when the barrel is compressed. The housing includes an aperture through which the barrel is accessible. 
     The invention can be viewed as providing a method for installing a fiber optic connector without using adhesives or requiring polishing in the field. In this regard, the method can be broadly summarized by the following steps. A preferred two part insert having a compliant portion and a support portion is inserted into a deformable barrel. A ferrule containing a pre-polished fiber stub is press-fitted to the barrel with the fiber stub extending partially into the insert. The barrel, including the insert and fiber stub ferrule, is disposed in a housing. The housing includes at least one aperture disposed therein such that the barrel is accessible through the aperture. A fiber is inserted into the insert via the barrel until the fiber contacts the fiber stub. Finally, the barrel can be contacted by any suitable member that can access the barrel through the aperture disposed in the housing. The barrel is preferably supported adjacent the support portion while a portion of the barrel adjacent the compliant portion is deformed. Pressure is applied to the barrel and the barrel deformed until the compliant portion deforms to trap the field inserted fiber and the fiber stub in the groove of the rigid insert. Preferably, but not necessarily simultaneously, a portion of the barrel extension extending beyond the housing is contacted by another portion of the tool and deformed to grip the buffered fiber therein. 
     Advantageously, a technician can join and secure the optical fibers in the insert and the barrel to the fiber buffer. Thereby, the optical fiber can be connected to a pre-polished fiber stub fixed within the barrel insert. Thus, the connector can be installed on an optical fiber in the field without the use of adhesive or epoxy or field polishing. 
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
     The invention can be better understood with reference to the following drawings. The components in the drawings are not necessarily to scale, emphasis instead being placed upon clearly illustrating the principles of the present invention. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views. 
     FIG. 1 is a perspective view of a fiber optic connector, embodying the principles of the invention; 
     FIG. 2 is an exploded perspective view of the fiber optic connector of FIG. 1; 
     FIG. 3 is an exploded perspective view of a barrel assembly of the fiber optic connector shown in FIG. 1; 
     FIG. 4 is a perspective view of a compliant portion of the insert of FIG. 3; 
     FIG. 5 is a perspective view of a support portion of the insert of FIG. 3; 
     FIG. 6 is a cross sectional view of a barrel assembly of the fiber optic connector FIG. 1; 
     FIG. 6 a  is an alternative embodiment of the barrel assembly of the fiber optic connector of FIG. 1; and 
     FIG. 7 is a cross sectional view of a barrel assembly of the fiber optic connector of FIG. 1 in the compressed position, as installed. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     While the invention is susceptible to various modifications and alternative forms, a specific embodiment thereof is shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that there is no intent to limit the invention to the particular form disclosed, but on the contrary, the invention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the claims. 
     The quick-connect fiber optic connector  10  of the present invention can be easily installed in a field setting without using epoxies or adhesives, or requiring field polishing is shown in FIGS. 1 and 2. The connector  10  according to the present invention is embodied in an LC-type connector. It should be appreciated that the principles of the invention disclosed herein can be applied to other known optical connectors, such as, for example, ST, SC, and FC varieties, and that the choice of an LC-type connector for the preferred embodiment is for illustrative purposes only. Although this version of the connector is intended for attachment to buffered fiber, the design can be readily extended to jacketed-type fiber. The connector  10  includes a housing  12  having disposed therein a barrel assembly  31  and an extender cap  20  extending from one end of the housing  12 . The exterior of the housing  12  preferably includes a latch arm  15  to facilitate mating of connector  10  with a complimentary connector or receptacle. As shown in FIG. 2, the housing  12  further includes a pair of apertures  14 — 14  disposed in each side thereof to provide access to the interior of the connector  10  and the barrel assembly  31  when disposed therein. Additionally, a pair of apertures  16 — 16  are also formed in the sides of the housing  12  which are arranged and configured to engage a pair snap flanges  21 — 21  (only one of which is shown) formed on the sides of the extender cap  20 , thereby holding the extender cap  20  in position and the barrel assembly  31  securely within the housing  12 . 
     FIG. 3 provides a prospective view of the components of the barrel assembly  31 . The barrel assembly  31  comprises a barrel  18  preferably of one unitary piece having two portions, a barrel body  23  and a barrel extension  24 . The barrel body  23  and the barrel extension  24  are preferably formed of differing diameters (the barrel body  23  having a larger diameter than the barrel extension  24 ) and are axially aligned to each other. The barrel body  23  is configured to support a fiber stub ferrule  26  at one end, which is press-fitted thereto, and has the barrel extension  24  extending from the opposite end of the barrel body  23 . Formed at the end of the barrel body  23  and configured to support the fiber stub ferrule  26 , are a pair of orientation recesses  19 — 19  (only one of which is shown) for orienting the insert  30  therein. The opposing end of the barrel body  23  includes an orientation flat  17  for orientation of the barrel assembly  31  within the housing  12 . Interior to the barrel  18 , the barrel body  23  is arranged and configured to receive the insert  30  (described hereinafter in more detail) and the barrel extension  24  includes a threaded portion  22  for gripping the buffer of a fiber inserted therein through the open end  25  of the barrel extension  24 , which is configured to receive a fiber inserted in the field. The barrel  18  can comprise a soft fully-annealed aluminum or any suitable material that allows for deformation upon a force being applied directly thereto. 
     The fiber stub ferrule  26  includes a fiber stub  28  supported therein. The fiber stub  28  is polished prior to positioning within the ferrule  26 . The ferrule  26  includes a hex coupling  27  configured to engage a comparable hex coupling (not shown) formed on the interior of the housing  12 , thereby aligning and orienting the barrel assembly  31  within the housing  12 . Therefore, an inserted fiber can be centered within the connector  10  and the barrel  18  will not rotate within the housing  12 . Further, the orientation of the barrel assembly  31  within the housing  12  is essential to ensure that the support portion  32  as seen in FIG. 6, for example, of the insert is adjacent one of the apertures  14  of the housing  12 , and that the compliant portion  34  is adjacent the other of the apertures  14  of the housing  12 . 
     FIGS. 4 and 5 illustrate the two preferred portions of the insert  30 . Specifically, FIG. 4 illustrates the compliant portion  34  of the insert  30  and FIG. 5 illustrates the support portion  32  of the insert. Looking first at FIG. 4, the compliant portion  34  includes a pair of flanges  38 — 38  and a contact rail  40  therebetween. At both ends, the compliant portion  34  includes angled or tapered access portions  41 — 41 . The compliant portion  34  is preferably injection molded and formed of a material having properties that provide for a readily deformable insert having low flow properties. The compliant portion  34  must also be resilient such that the compliant portion  34  substantially corresponds to the barrel  18  during compression of the barrel  18  and after the force is removed. 
     Turning now to FIG. 5, the support portion  32  of the insert  30  includes a pair of orientation flanges  33 — 33  to be engaged by the pair of orientation recesses  19 — 19  (FIG. 3) disposed at one end of the barrel body  23  for orienting the insert  30  within the barrel assembly  31 . The support portion  32  further includes a capillary or groove  36  disposed longitudinally and preferably centered on the portion  32  and extending the full length of the portion  32 . The groove  36  is arranged and configured to receive both the fiber stub  28  and a field inserted fiber. Although a groove  36  in the shape of “V” having a 90 degree angle and having a depth such that the top of the fiber stub  28  and the inserted fiber are substantially flush with the plane of the surfaces on either side of the groove  36 , provides a preferable arrangement, it should be understood that any capillary or groove capable of supporting fibers is suitable. Both ends of the support portion  32  also include an angled access portion  35 — 35 . These access portions  35 — 35 , however, are preferably at an angle (for example 30 degrees) that is relatively greater than the angle of the access portions  41 — 41  (for example 20 degrees) of the compliant insert  34  (FIG.  4 ). When the insert  30  is assembled, the angled access portions  35 — 35  of the support portion  32  together with the angled access portions  41 — 41  of the compliant portion  34  provide for a fully enclosed entry cone for the field inserted fiber thereby cutting down on fiber misplacement during insertion of a fiber into the connector  10 . The offsetting of the angled portions  35 — 35  of the support portion  32  from the angled portions  41 — 41  of the compliant portion  34  provides a tolerance for deformation of the entry cone without damaging the field inserted fiber when the compliant portion  34  is deformed to fix the fibers in the groove  36 . The support portion  32  is preferably injection molded and formed of a substantially rigid plastic material that resists deformation when a force is applied to the barrel  18  within which the insert  30  is contained. 
     A cross-section of the barrel assembly  31  is illustrated in FIG.  6 . The insert  30  comprising the support portion  32  and the compliant portion  34  is disposed within the barrel  18 , more specifically, the barrel body  23  portion of the barrel  18 . The insert  30  is arranged within the barrel  18  such that the orientation flanges  33 — 33  of the support portion  32  engage the orientation recesses  19 — 19  of the barrel  18 , the groove  36  is substantially centered within the barrel  18 , and a portion of the support portion  32  opposing the groove  36  is flush with an interior surface of the barrel  18 . The compliant portion  34  of the insert  30  is arranged and configured such that the flanges  38 — 38  initially provide clearance between the contact rail  40  and the groove  36  to provide for easy insertion of a fiber in the groove  36 . It is further preferable that the portion of the compliant insert  34  opposing the contact rail  40  is flush with an interior surface of the barrel  18 . 
     Referring now to FIG. 7, illustrated is a cross section of the barrel assembly  31  after a fiber has been inserted in the field to contact the fiber stub  28  and pressure has been applied to the barrel  18 . The support portion  32  remains undeformed while the barrel  18  adjacent the compliant portion  34  is deformed thereby deforming the compliant portion  34 . The compliant portion  34  is compressed and deformed toward the groove  36  and the flanges  38  are displaced outward, away from the groove  36  and toward the barrel  18 . Once the connector  10  is assembled and a fiber is inserted into the connector  10 , the groove  36  supports both the fiber stub  28  and a portion of the fiber inserted in the field. Upon the deformation of the insert  30 , the contact rail  40  acts to crimp both the fiber stub  28  and an inserted fiber into the groove  36  and in contact with each other. 
     FIG. 6 a  illustrates an alternative embodiment of the insert  30  as disposed within a barrel  18 . This alternative embodiment of the insert  30  includes a similar two-part configuration having a support portion  32  and a compliant portion  34  which are oriented in a similar fashion to that described regarding FIG.  6 . The compliant portion  34 , however, includes a substantially rigid strip  42  bonded thereto. The rigid strip  42  is aligned with the groove  36  of the rigid portion  32  for transferring the load from the compliant portion  34  to the field installed fiber and the fiber stub  28  in the groove  36 . 
     In use, a portion of the connector  10  is assembled in a factory or pre-manufactured. The fiber stub  28  is pre-polished and inserted into the fiber stub ferrule  26 . The insert  30  is positioned within the barrel  18  and the fiber stub ferrule  26  is disposed on the barrel  18  such that the fiber stub  28  extends into the groove  36  of the insert  30  to form the barrel assembly  31 . The barrel assembly  31  is inserted and oriented in the housing  12  using the barrel orientation flat  17 . The extender cap  20  is disposed on the barrel extension  24  and “snapped” into place, using the snap flanges  21 — 21  on the extender cap  20  and the apertures  14 — 14  on the housing  12 , to hold the barrel assembly  31  in the housing  12 . During manufacturing a drop of index matching gel can be inserted in the connector to minimize loss at the splicing point between the field inserted fiber and the fiber stub  28 . Dust caps (not shown) can be press-fitted on both ends of the connector  10  to keep the interior of the connector  10 , including the index matching gel, clean during shipping. In the field, a buffered fiber can be stripped, cleaved, and inserted into the open end  25  of the barrel  18 . The entry cone formed by the angled portions  41 — 41  of the compliant portion  34  and the angled portions  35 — 35  of the rigid portion  32  guides the field inserted fiber into the insert  30 . The groove  36  of the support portion  32  of the insert  30  aligns the field inserted fiber with the fiber stub  28 . A tool can then be used to, preferably simultaneously, engage the barrel  18  through the aperture  14  disposed in the side of the housing  12  and to engage a portion of the barrel extension  24  extending beyond the extender cap  20 . The tool preferably includes a shaped portion to support, without deforming, the barrel  18  adjacent the support portion  32  of the insert  30  and a flat portion for engaging the barrel  18  adjacent the compliant portion  34  of the insert  30 . The tool is then operated to apply pressure to the barrel  18  and the barrel extension  24 . Upon the application of such pressure, the barrel  18  deforms and engages the compliant portion  34  of the insert  30  causing the clearance flanges  38 — 38  to deform and spread away from the groove  36  until the contact portion  40  contacts the fibers thereby crimping the field inserted fiber and the fiber stub  38  into the groove  36  (as shown in FIG.  7 ). The threaded portion  22  interior to the barrel extension grips the field inserted buffered fiber extending therethrough upon deformation. Although a tool is referenced herein for crimping the fiber stub and fiber into position, it will be understood by those with ordinary skill in the art that any means of accessing the necessary portions of the connector to achieve crimping will be suitable. 
     The principles in the present invention can also be applied to connectors used with jumper cables that typically use an internal spring to provide an axial bias force for the ferrule and barrel components. 
     Although a preferred embodiment of the invention has been disclosed in detail herein, it will be obvious to those skilled in the art that variations and modifications of the disclosed embodiment can be made without departing from the spirit and scope of the invention as set forth in the claims.