Abstract:
A ruggedized fiber optic connector assembly includes a substantially hollow plug housing; and a glue body disposed within the substantially hollow plug housing; wherein the glue body includes a first portion that is configured to engage and retain an optical cable comprising an optical fiber and one or more strength members; wherein the glue body includes a second portion that is configured to engage and retain a connector sub-assembly comprising an optical ferrule; wherein the second portion of the glue body includes a pair of opposed snap hooks that are configured to engage a corresponding pair of opposed recesses of the connector sub-assembly; and wherein the optical fiber and the optical ferrule are optically coupled.

Description:
RELATED APPLICATIONS 
       [0001]    The present application is a Divisional of U.S. Ser. No. 11/504,349 filed on Aug. 15, 2006, the disclosure of which is incorporated by reference herein in its entirety. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates generally to a ruggedized fiber optic connector assembly, also referred to as a fiber optic “plug.” More specifically, the present invention relates to a ruggedized fiber optic connector assembly that incorporates a retention body, or glue body, that is configured to both retain a fiber optic cable, preferably having one or more strength members, and engage a fiber optic receptacle or, alternatively, another fiber optic connector assembly. 
         [0004]    2. Technical Background of the Invention 
         [0005]    Optical fiber is increasingly being used for a variety of broadband applications, including voice, video, and data transmission. As a result, fiber optic communications networks include a number of interconnection points at which multiple optical fibers are interconnected. Fiber optic communications networks also include a number of connection terminals, examples of which include, but are not limited to, network access point (NAP) enclosures, aerial closures, below grade closures, pedestals, optical network terminals (ONTs), network interface devices (NIDs), and multi-port devices. In certain instances, the connection terminals include connector ports, typically opening through an external wall of the connection terminals, that are used to establish optical connections between optical fibers that are terminated from a distribution cable and respective optical fibers of one or more pre-connectorized drop cables, extended distribution cables, tether cables, or branch cables, collectively referred to as “drop cables.” The connection terminals are used to readily extend fiber optic communications services to a subscriber. In this regard, fiber optic communications networks are being developed that deliver “fiber-to-the-curb” (FTTC), “fiber-to-the-business” (FTTB), “fiber-to-the-home” (FTTH), and “fiber-to-the-premises” (FTTP), generically referred to as “FTTx.” 
         [0006]    A conventional connector port opening through an external wall of a connection terminal typically includes a receptacle that is configured to receive a connectorized optical fiber on the inside of the terminal, and a connectorized drop cable on the outside of the terminal. One of the mating ferrules is mounted on the end of an optical fiber that is optically interconnected to at least one optical fiber of the distribution cable within the connection terminal. The other mating ferrule is mounted on the end of an optical fiber of a drop cable that is inserted into the receptacle from the outside of the connection terminal. An alignment sleeve of the receptacle typically assists in the alignment of the ferrules, and ferrule guide pins or other alignment means may further assist in the precise alignment of multifiber ferrules. 
         [0007]    In particular, a plug mounted on the end of the drop cable engages one side of a corresponding receptacle. Typically, the plug includes a substantially cylindrical plug body, and a fiber optic connector including a plug ferrule disposed within the plug body. The end of the plug body is open, or is provided with one or more openings, such that the ferrule is accessible within the plug body, for example to be cleaned. The ferrule is mounted on the end of one or more optical fibers of the drop cable such that mating the plug with the receptacle aligns the optical fibers of the drop cable with the respective optical fibers terminated from the distribution cable within the connection terminal. In the process of mating the plug with the receptacle, the ferrule is inserted into one end of the alignment sleeve housed within the receptacle. As a result of the construction of a conventional plug, the alignment sleeve is minimally received within the open end of the plug body as the ferrule is inserted into the alignment sleeve. As an alternative to the above, the plug mounted on the end of the drop cable engages a plug mounted on the end of another drop cable or another receptacle not associated with a connection terminal, such as that associated with a business, home, premises, etc. 
         [0008]    Several different types of conventional connectors have been developed, examples of which include, but are not limited to, SC, ST, LC, MTP, MT-RJ, and SC-DC. The size and shape of the ferrule of each of these connectors is somewhat different. Correspondingly, the size and shape of the plug body and alignment sleeve are somewhat different. As a result, in conventional practice, different plugs and receptacles are used in conjunction with different ferrules. In this regard, the receptacles generally define different sized internal cavities and features corresponding to different sized alignment sleeves and plug bodies, and, in turn, different ferrules disposed within the plug bodies and alignment sleeves. 
         [0009]    Referring to prior art  FIG. 1 , a conventional connector  10  includes a plug housing  12  in which a crimp body  14  including two halves  14   a , 14   b  and a crimp band  16  are axially disposed during assembly. A heat shrink  18  is also utilized, as described in greater detail below. Collectively, the crimp body  14  and crimp band  16  retain both a drop cable  20  and a connector sub-assembly  22  (i.e., a pre-assembled ferrule holder module), the connector sub-assembly  22  holding a ferrule  24 . Specifically, a shaft  25  of the connector sub-assembly  22  is secured between the two halves  14   a , 14   b  of the crimp body  14 . As a result, an optical fiber of the drop cable  20  and the ferrule  24  are optically connected. The heat shrink  18  is disposed about an end portion of the plug housing  12  and an end portion of the drop cable  20 , thereby providing some retention force and stress relief, and a flexible environmental seal. As illustrated, the drop cable  20  is a single-fiber drop cable and the ferrule  24  is a single-termination ferrule, although other types of drop cables, optical fibers, and ferrules could be used with other types of connectors. This inner assembly is partially housed within a coupling nut  26  that is externally threaded such that the connector  10  is configured to engage the internal threading of an alignment sleeve of a receptacle (not shown), thereby aligning and optically mating the ferrule  24  of the connector  10  and a ferrule of the receptacle. As described above, guide pins or other alignment means may assist in more precise alignment of multi-fiber ferrules. For example, the end of the plug housing  12  and the alignment sleeve and/or receptacle may be keyed. The connector  10  also includes one or more silicone O-rings  28  that environmentally seal the connector  10  and receptacle, when joined, and a boot  30  that further relieves stress in the drop cable  20 . Finally, the connector  10  incorporates one or more dust caps  32 , 34  that are used to selectively protect the ferrule  24  and the exposed end of the plug housing  12 . Preferably, the larger of the dust caps  34 , also referred to as the “pulling cap,” is internally threaded such that it is configured to engage the external threading of the coupling nut  26 . Finally, the pulling cap  34  is secured to the boot  20  via a plastic lanyard  36  or other retention means, such that the pulling cap  34  is not easily lost. The connector  10  provides a hardened connector for outside plant deployment and incorporates an integral pulling eye  38  designed for pulling tension. 
         [0010]    As of yet, however, there is an unresolved need for an alternative (or additional) retention method for dealing with otherwise incompatible drop cable strength members, such as glass-reinforced plastic (GRP) strength members and the like. The handling and mating of the two halves  14   a , 14   b  of the crimp body  14  described above often applies excessive stress and jeopardizes the optical fiber (which typically has a diameter of about 250 μm) during termination. Further, this crimp design alone is typically not strong enough to meet pulling tension requirements, necessitating the use of an adhesive. This adhesive rigidly fixes the connector sub-assembly, eliminating the ability to compensate for radial offset due to manufacturing tolerances. This radial offset can be compensated for by “floating” the adapter, however, in a plug-to-plug arrangement, there is no such floating element. Thus, manufacturing tolerances become much more stringent. Still further, this crimp design, incorporating the heat shrink  18 , relies on a hard stop of the plug housing  12  against the coupling nut  26  and, ultimately, the heat shrink  18  itself to keep the drop cable  20  and the connector sub-assembly  22  in the same position during process and use. In a high temperature environment, and due to improper fixturing during the application of the heat shrink  18 , the plug housing  12  is allowed to move axially and piston in and out of position. As of yet, there is also an unresolved need for an alternative retention method that does not allow multiple ways (i.e., two 180-degree opposing ways) to assemble the connector components, thereby requiring fixturing and verification by an operator in order to make sure that the connector sub-assembly  22  is oriented properly. On occasion, this requires the cutting off of a good connector as the orientation of the endface angle is incompatible, resulting in wasteful scrap. 
       SUMMARY OF THE INVENTION 
       [0011]    In one embodiment of the present invention, a ruggedized fiber optic connector assembly includes a substantially hollow plug housing; and a retention body disposed within the substantially hollow plug housing; wherein the retention body includes a first portion that is configured to engage and retain an optical cable comprising an optical fiber and one or more strength members; wherein the retention body includes a second portion that is configured to engage and retain a connector sub-assembly comprising an optical ferrule; and wherein the optical fiber and the optical ferrule are optically coupled. 
         [0012]    In another embodiment of the present invention, a ruggedized fiber optic connector assembly includes a substantially hollow plug housing; and a retention body disposed within the substantially hollow plug housing; wherein the retention body includes a first portion that is configured to engage and retain an optical cable comprising an optical fiber and one or more strength members; wherein the retention body includes a second portion that is configured to engage and retain a connector sub-assembly comprising an optical ferrule; wherein the second portion of the retention body includes a pair of opposed snap hooks that are configured to engage a corresponding pair of opposed recesses of the connector sub-assembly; and wherein the optical fiber and the optical ferrule are optically coupled. 
         [0013]    In a further embodiment of the present invention, a ruggedized fiber optic connector assembly includes a substantially hollow plug housing; and a glue body disposed within the substantially hollow plug housing; wherein the glue body includes a first portion that is configured to engage and retain an optical cable comprising an optical fiber and one or more strength members; wherein the glue body includes a second portion that is configured to engage and retain a connector sub-assembly comprising an optical ferrule; wherein the second portion of the glue body includes a pair of opposed snap hooks that are configured to engage a corresponding pair of opposed recesses of the connector sub-assembly; and wherein the optical fiber and the optical ferrule are optically coupled. 
         [0014]    Additional features and advantages of the present invention will be set forth in the detailed description which follows, explaining the principles and operations thereof, and will also be readily apparent to those of ordinary skill in the art from the description and/or recognized by practicing the invention as described. It is to be understood that the general description above and the detailed description which follows present exemplary embodiments of the invention, which are intended to provide an overview and framework for understanding the nature and character of the invention as it is claimed. The accompanying drawings are incorporated into and constitute a part of this specification, illustrating and further highlighting the exemplary embodiments of the present invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0015]      FIG. 1  is a perspective and exploded perspective view of a conventional connector. 
           [0016]      FIG. 2  is a perspective view of one embodiment of the connector assembly of the present invention. 
           [0017]      FIG. 3  is a cut-away perspective view of the connector assembly of  FIG. 2 , highlighting the use of a glue body that is configured to retain both a drop cable having one or more strength members and a connector sub-assembly. 
           [0018]      FIG. 4  is another cut-away perspective view of the connector assembly of  FIG. 2 , highlighting the use of a glue body that is configured to retain both a drop cable having one or more strength members and a connector sub-assembly. 
           [0019]      FIG. 5  is an isolated perspective view of the assembled glue body and connector sub-assembly of  FIGS. 3 and 4 . 
           [0020]      FIG. 6  is an isolated perspective view of the glue body of  FIGS. 3-5 . 
           [0021]      FIG. 7  is another isolated perspective view of the glue body of  FIGS. 3-5 , highlighting the joining of a substantially flat drop cable incorporating an optical fiber and a pair of GRP strength members with the glue body. 
           [0022]      FIG. 8  is an isolated perspective view of an end cap used in conjunction with the connector assembly of  FIG. 2 . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0023]    Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Whenever possible, like reference numbers will be used to refer to like components or parts. 
         [0024]    Referring to  FIG. 2 , the connector assembly  40 , also referred to herein as a “plug”, of the present invention includes a plug housing  42  that contains a connector sub-assembly  44  (i.e., a pre-assembled ferrule holder module), the connector sub-assembly  44  holding a ferrule  46 . The connector sub-assembly  44  and ferrule  46  are accessible through one open end of the plug housing  42 , such that the ferrule can be optically connected to the ferrule of a receptacle or another connector assembly, or plug. The shrouding fingers  48  of the connector assembly  40  are reduced in length as compared to the conventional connector  10  ( FIG. 1 ) in order to allow two connector assemblies to better mate with one another, among other things. Any reduced protection that results is compensated for by increased flexibility in situations requiring a more protruding ferrule  46 . The more protruding ferrule  46  also allows for more efficient pre-assembly and termination, including polishing, etc. The keyed configurations of the inner assembly and plug housing  42  of the connector assembly  40  require that the connector assembly  40  be assembled in one specific orientation, as described in greater detail below. This addresses the unresolved need for an alternative retention method that does not allow multiple ways (i.e., two 180-degree opposing ways) to assemble the connector components, thereby eliminating the requirement for fixturing and verification by an operator in order to make sure that the connector sub-assembly  44  is oriented properly. The other end of the plug housing  42  is more open as compared to the conventional connector  10 . This fact, and the configuration of the end cap  50  used, described in greater detail below, allow for relatively free flexural movement of the plug housing  42  relative to a substantially flat drop cable  52  that incorporates one or more GRP strength members  54  ( FIGS. 3 ,  4 , and  7 ) or the like, for example. The one or more silicone O-rings  28  ( FIG. 1 ) of the conventional Optitap connector  10  may be replaced with a single integrally formed and overmolded O-ring  56  that is disposed within a recessed channel  58  that is manufactured into the exterior surface of the plug housing  42 . Optionally, the exterior surface of the plug housing  42  includes a number of convenient gripping surfaces. 
         [0025]    Referring to  FIG. 3 , internally, the connector assembly  40  includes a retention body  60 , or glue body, having a pair of snap hooks  62  configured to engage a pair of snap hook recesses  64  manufactured into opposing sides of the connector sub-assembly  44 , the snap hooks  62  retaining the connector sub-assembly  44  against the glue body  60  once it is “snapped” into place. These snap hooks  62  each comprise a protruding “finger” member having a “hooked” end. Because the finger members have a degree of flexibility, they are deflected out of place or bent as the connector sub assembly  44  is pressed between them and “snap” back into place when the hooked ends of the finger members engage the snap hook recesses  64 . Once the plug housing  42  is secured over the retention body and snap hooks, an interior surface of the plug housing  42  may contact the exterior surface of the snap hooks  62 , maintaining the snap hooks  62  within the snap hook recesses  64 . Advantageously, the snap hooks  62  or another sub-assembly retention feature allow the connector sub-assembly  44  to rotate slightly (+/−about 5 degrees maximum) about the axis of the glue body  60  and connector assembly  40 , as the snap hook recesses  64  are somewhat oversized with respect to the snap hooks  62 . The connector parts will self-align below about 45 degrees if the proper chamfer and lead-in detail exists, thus the sub-assembly retention feature allows the connector sub-assembly  44  to rotate less than about 45 degrees. This inherent radial float reduces the stringency of the manufacturing tolerances involved. This is especially important in an in-line application, where two connector assemblies are relatively rigidly aligned with respect to one another in order to meet mechanical performance requirements. In such applications, an alignment sleeve disposed between the connector assemblies is often not capable of adequately adjusting to both connector assemblies, which can have contrary orientations. The shaft  25  ( FIG. 1 ) of the connector sub-assembly  44  is preferably disposed and held within a bore  66  ( FIG. 6 ) manufactured into the end of the glue body  60  having the snap hooks  62 . This end also includes a pair of alignment blocks  68  that are designed to ensure the proper positioning of the connector sub-assembly  44  on the face of the glue body  60 . 
         [0026]    Referring to  FIGS. 4 and 5 , the glue body  60  engages the plug housing  42  ( FIG. 4 ) by means of one or more recesses  70  manufactured into the exterior surface of the glue body  60  and one or more corresponding protrusions  72  ( FIG. 4 ) manufactured into the interior surface of the plug housing  42 . Accordingly, the glue body  60  is “snapped” into place within the interior of the plug housing  42 . Again, the materials chosen facilitate this and either or both of the recesses  70  or protrusions  72  can have complimentary angled surfaces. Advantageously, this mechanical retention of the glue body  60  within the interior of the plug housing  42  alleviates the problem of endface position variance due to heat shrink pistoning. Importantly, the exterior surface of the glue body  60  and the interior surface of the plug housing  42  also include corresponding flattened and raised surfaces. Thus, the keyed configurations of the glue body  60  and plug housing  42  of the connector assembly  40  ( FIG. 4 ) require that the connector assembly  40  be assembled in one specific orientation. Again, this addresses the unresolved need for an alternative retention method that does not allow multiple ways (i.e., two 180-degree opposing ways) to assemble the connector components, thereby eliminating the requirement for fixturing and verification by an operator in order to make sure that the connector sub-assembly  44  is oriented properly. The geometries involved rely on material flexibility and utilize minor localized interferences between the semi-rigid bodies involved to determine molding tolerances, while maintaining mechanical integrity. 
         [0027]    Referring to  FIG. 6 , the glue body  60  includes a relatively larger diameter portion  74  and a relatively smaller diameter portion  76 , the larger diameter portion  74  located proximal to the end of the glue body  60  having the snap hooks  62  and the smaller diameter portion  76  located distal to the end of the glue body  60  having the snap hooks  62 . When the glue body  60  is inserted into the plug housing  42 , this larger diameter portion  74  acts as a natural stop as it contacts a shelf  78  manufactured into the interior surface of the plug housing  42  (see  FIG. 4 ). As described above, the shaft  25  ( FIG. 1 ) of the connector sub-assembly  44  ( FIGS. 2-5 ) is preferably disposed and held within the bore  66  manufactured into the end of the glue body  60  having the snap hooks  62 . This end also includes the pair of alignment blocks  68  that are designed to ensure the proper positioning of the connector sub-assembly  44  on the face of the glue body  60  in conjunction with the snap hooks  62 . 
         [0028]    In an alternative embodiment, the shaft  25  of the connector sub-assembly  44  is disposed and held between the two halves  14   a , 14   b  ( FIG. 1 ) of the former crimp body  14  ( FIG. 1 ), which is now eliminated. These are, in turn, disposed within the bore  66  manufactured into the end of the glue body  60  having the snap hooks  62 . As above, this keeps the connector sub-assembly  44  centered with respect to the glue body  60  and the plug housing  42 . In another alternative embodiment, the two halves  14   a , 14   b  of the former crimp body  14  are combined into a single crimp retainer (not shown) which is disposed within the bore  66  manufactured into the end of the glue body  60  having the snap hooks  62 . Again, this keeps the connector sub-assembly  44  centered with respect to the glue body  60  and the plug housing  42 . 
         [0029]    Referring to  FIG. 7 , the glue body  60  also includes a central channel  80  positioned to receive at least one optical fiber  82  of the drop cable  52  and a pair of edge channels  84  positioned to receive GRP strength members  54  or other strength members of the drop cable  52 . The optical fiber  82  (which typically has a diameter of about 250 μm) and the pair of GRP strength members  54  are encased within a drop cable sheath  86 , as is well known to those of ordinary skill in the art. Although GRP strength members  54  are illustrated and described herein, the drop cable  52  can include other kinds of strength members as well, or as an alternative. Any such strength members can be accommodated by one or more channels manufactured into the glue body  60 . Preferably, the pair of GRP strength members  54  protrude between about 10 mm and about 20 mm (and more preferably, about 17 mm) into the pair of edge channels  84  and the edge channels  84  are filled with an adhesive that serves to bond the drop cable  52  to the glue body  60 . The adhesive can be a visible light curable epoxy, or an ultraviolet (UV) light or heat curable glue. All material choices depend upon the pull strength, temperature exposure range, and chemical resistance desired. In the case that a visible light curable epoxy is used, the glue body  60  is preferably substantially transparent such that visible light can reach and cure the epoxy. For example, a natural poly ether imide can be used, also providing a relatively high temperature resistance. This substantially transparent material allows for visual feedback during the adhesive filling and optical fiber routing processes. Advantageously, the pair of edge channels  84  separate the adhesive from the central channel  80  and the optical fiber  82 . Because the edge channels  84  are sealed, material is prevented from flowing into the connector assembly  40  ( FIGS. 2-4 ) internals during assembly. The connector assembly  40  of the present invention readily meets about the 100 lbf pull strength requirement desired, due to the use of the glue body  60  and the adhesive. During assembly, preferably, the drop cable  52  is secured to the glue body  60  first, and then the connector sub-assembly  44  ( FIGS. 2-5 ) is attached to the glue body  60 . 
         [0030]    In an alternative embodiment, the pair of edge channels  84  are configured to accept a pair of wedge-type clamps which are held in place by a pair of uncrimped bands. These wedge-type clamps and uncrimped bands are subsequently fixed onto the GRP strength members  54  by crimping, thereby securing the drop cable  52  to the glue body  60 . This represents a non-adhesive solution. 
         [0031]    Referring to  FIG. 8 , the end cap  50  described above includes an insertion end  88  that is configured to be inserted snugly into the “back” end of the plug housing  42  ( FIGS. 2 and 3 ). The end cap  50  also includes a tapering end  90  that is manufactured with a slot opening  92  that is configured to receive the substantially flat drop cable  52  ( FIG. 7 ), which passes through the end cap  50  and into the plug housing  42 . 
         [0032]    As described above, the retention body  60  of the present invention is coupled to the connector sub-assembly  44  by one or more coupling features, such as the retention snap hooks  62 . In conventional connector assemblies, optical fibers and/or strength member movement over time may cause the connector assembly, including the ferrule, to protrude or push forward relative to the connector outer housing or plug shroud, thus resulting in a defective drop cable incapable of proper interconnection. Stops positioned about protrusion  72  may prevent the retention body  60 , once snapped into place, from being removed through the front, or connective, end of the plug assembly. Thus, as the fibers or strength members push forward into the retention body  60 , the retention body may be stopped from moving internally within the plug housing  42  beyond a predetermined point. By coupling the connector sub-assembly  44  to the retention body  60 , the connector sub-assembly is then also prevented from protruding beyond a predetermined point, providing a drop cable capable of proper interconnection over time. In one embodiment, the plug housing  42 , retention body  60  and their contact points are capable of withstanding forces up to about 50 lbs. 
         [0033]    Although the present invention has been illustrated and described herein with reference to preferred embodiments and specific examples thereof, it will be readily apparent to those of ordinary skill in the art that other embodiments and examples can perform similar functions and/or achieve like results. For example, the mating of two connector assemblies could be achieved by providing a “female” version of the connector assembly (i.e., an outlet). The mating order would be plug-outlet-plug. All such equivalent embodiments and examples are within the spirit and scope of the present invention and are intended to be covered by the following claims.