Abstract:
A two-piece spring push includes a main body portion and a cap. The cap is attached to the main body portion through frictional or interference fits of projections and openings in the two-piece spring push. The two-piece spring push allows for the use of the spring push on larger diameter optical cables as the spring push is assembled on the optical fibers after the optical fibers are terminated in an optical ferrule.

Description:
REFERENCE TO RELATED CASE 
     This application claims priority under 35 U.S.C. §119 (e) to provisional application Ser. No. 61/445,391, filed on Feb. 22, 2011, which is hereby incorporated by reference in its entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The use of large outer diameter fiber optic cables with MT ferrules poses a problem with the standard components used to terminate those ferrules. One of those components is the spring push. In some fiber optic connectors, including those that use the MT ferrules, a spring push is used to bias a spring against the back end of the ferrule or a pin clamp. The back end of the spring push is typically cylindrical in shape and is used in conjunction with a crimp band to secure the strength member of the fiber optic cable (typically aramid fibers) to the fiber optic connectors. The spring push is usually disposed over the end of the fiber optic cable prior to terminating the end of the optical fibers in the ferrule. This requires that the spring push be large enough to pass over the outer diameter of the fiber optic cable so that it will be out of the way during assembly. In its final position, however, the spring push need not be so large. Thus, the spring push could be attached after the optical fibers are attached to the optical ferrule, but that requires a two-piece component. A two-piece component must be able to be secured to the fiber optic connectors in a relatively quick manner and at the same time be robust enough to withstand the forces placed on the fiber optic connectors in the field. 
     A two-piece spring push, which meets all applicable standards, including FOCIS 5 and IEC-61754-7, includes projections and corresponding openings that frictionally engage one another, and in conjunction with the use of a crimp band, may be used with the larger optical fiber cables and may be applied in the field. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to a two-piece spring push for use with a fiber optic connector that includes a main body, the main body having a front end, a back end, and a middle portion disposed therebetween, the front end comprising two generally parallel extensions extending from the middle portion, the back end forming at least a portion of a cylinder, and a cap configured to mate with the main body, the cap engaging at least a portion of the middle portion of the main body and at least a portion of the back end, the cap and the main body forming an opening through at least a portion of the spring push. 
     In some embodiments, the cap has at least two alignment features to align the cap with the main body. 
     In some embodiments, the cap has five projections, the five projections corresponding to five openings on the main body, each of the five projections to be frictionally disposed within a corresponding one of the five openings on the main body to hold the cap to the main body. 
     In another aspect, the invention is directed to a pring push for a fiber optic connector that includes a main body and a cap, the main body and cap secured to one another only by friction caused by mating the main body and cap, an opening formed by the mated main body and cap extending through at least a portion of the spring piece, and a crimp body formed by the mating of the main body and cap at a back end thereof. 
     In yet another aspect, the invention is directed to method of assembling a spring push on terminated optical fibers that includes the steps of providing a plurality of optical fibers terminated on an optical ferrule, providing a two-piece spring push, the two-piece spring push having a main body with a groove therein and a cap portion configured to mate with the main body and having a groove therein that corresponds to the groove in the main portion, the two grooves forming an opening therein when the main body and cap are mated with one another to allow the spring push to be moved along the plurality of optical fibers, disposing the plurality of optical fibers in the groove of the main body rearwardly of the optical fiber, aligning the cap over the plurality of optical fibers disposed in the groove of the main body, inserting at least one first projection on the cap into a corresponding first opening in the main body, and pressing the cap onto the main body such that at least one second projection engages a at least one second opening, the at least one second projection frictionally engaging the at least one second opening to retain the cap on the main body. 
     Additional features and advantages of the invention will be set forth in the detailed description which follows, and in part will be readily apparent to those skilled in the art from that description or recognized by practicing the invention as described herein, including the detailed description which follows, the claims, as well as the appended drawings. 
     It is to be understood that both the foregoing general description and the following detailed description of the present embodiments of the invention, and are intended to provide an overview or framework for understanding the nature and character of the invention as it is claimed. The accompanying drawings are included to provide a further understanding of the invention, and are incorporated into and constitute a part of this specification. The drawings illustrate various embodiments of the invention and, together with the description, serve to explain the principles and operations of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side perspective view of one embodiment of a two-piece spring push according to the present invention with portions of optical fibers disposed therein; 
         FIG. 2  is a top perspective view of a main body portion of two-piece spring push of  FIG. 1 ; 
         FIG. 3  is a front perspective view of a cap portion of the two-piece spring push of  FIG. 1 ; 
         FIG. 4  is a perspective view of the two-piece spring push of  FIG. 1  assembled and the crimp band and strain-relief boot to be used on an associated fiber optic connector; 
         FIG. 5  is a cross section view of the two-piece spring push of  FIG. 4  along the lines  5 - 5 ; and 
         FIG. 6  is a perspective view of another embodiment of a two-piece spring push according to the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Reference will now be made in detail to the present preferred embodiment(s) of the invention, examples of which are illustrated in the accompanying drawings. Whenever possible, the same reference numerals will be used throughout the drawings to refer to the same or like parts. 
     Referring to  FIG. 1 , a two-piece spring push  100  for use with a fiber optic connector is illustrated. The two-piece spring push  100  has a main body  102  and a cap  104  that frictionally connects to the main body  102 . The main body  102  has a front end  106 , a back end  108 , and a middle portion  110 . The front end  106  has two extensions  112  that, as is known in the art, engage the connector body in a fiber optic connector, particularly in the MT type connectors. The two extensions  112  keep a spring centrally located, the spring being used to bias the ferrule forward in the connector. The size and shape of the extensions  112  are not critical to the invention and may be shorter, longer, thicker, etc., and still fall within the scope of the present invention. 
     As best illustrated in  FIGS. 1 and 2 , the back end  108  of the main body  112  is illustrated as a half cylinder  114 . The half cylinder  114  has a flat upper surface  116 , which, as described in more detail below, will mate with a corresponding surface on the cap  104 . The half cylinder  114  also has two openings  118  extending downward and from the flat upper surface  116 . The openings  118  are in communication with the outer surface  120  of the half cylinder, but they could be wholly contained within the half cylinder  114 . The outer surface  120  of the back end  108  preferably has ridges or ribs  122  to assist in capturing the strength members (not shown) in the fiber optical cable used with the two-piece spring push  100 . While the back end  108  is illustrated as being cylindrical, it could be of any shape and/or configuration and still fall within the scope of the present invention. 
     The back end  108  of the two-piece spring push  100  also has a groove  130  that extends through the back end  108  and, as noted below in more detail, preferably through the middle portion  110  as an opening  132 . As can be seen in  FIG. 1 , the optical fibers  300  are to be disposed within the groove  130 /opening  132  of the main body  102 . 
     The middle portion  110  of main body  102  is preferably a shoulder that connects the back end  108  and the extensions  112  on the front end  106 . The middle portion also functions as a stop for the two-piece spring push  100  when inserted into the fiber optic connector (not shown). The middle portion  110  has two openings  140  that extend into the middle portion  110  from the back end  108  to accept projections in the cap  104 . The middle portion  110  also has an opening  142  that is in communication with the opening  132 . As described in more detail below, the opening  142  functions as a locator for the cap  104  and also to assist in maintaining the structural integrity of the two-piece spring push  100 . 
     It should be noted that there is a transitional area  150  between the back end  108  and the middle portion  110 . The transitional area  150  is preferably a rounded area that transitions from the flat upper surface  116  to the rear facing surface  152  of the middle portion  110 . The transitional area  150  assists in the mating of the cap  104  to the main body  102  as described below. 
     The cap  104  of two-piece spring push  100  is best illustrated in  FIGS. 1 &amp; 3 . The cap  104  has a front end  160  and a back end  162 . The back end  162  has a half cylinder  164 . The half cylinder  164  has a flat lower surface  166  that mates with the flat upper surface  116  of the main body  102 . The cap  104  also has a groove  168  that extends from the front end  160  to the back end  162 . As noted above, the groove  168  aligns with the groove  130  to form the opening  132 . See  FIG. 5 . The back end  162  also has two projections  170  extending downward and from the flat lower surface  166 . The projections  170  are adjacent to the outer surface  172  of the half cylinder  164  and are aligned with the two openings  118 . Thus, the projections  170  should be located on the cap  104  to correspond with the location of the two openings  118 . The projections  170  have a chamfered portion  174 , so that when the cap  104  is mated to the main body, the projections  170  can be inserted into the openings  118 . The projections  170  could also have rounded surfaces rather than the flat, chamfered surfaces as illustrated. 
     The outer surface  172  of the back end  162  preferably has ridges or ribs  176  as did the back end  108  above. 
     The front end  160  of cap  104  terminates, as illustrated in  FIG. 1 , at the middle portion  110  of the main body  102 . The front end  160  has a center projection  180  that extends downward from the front end  160  and aligns with the opening  142  and is in communication with the opening  132 . The center projection  180  assists the user in aligning the cap  104  with the main body  102  during assembly. 
     The front end  160  of cap  104  also has two projections  182 , which are to mate with the openings  140  in the middle portion  110  of the main body  102 . It is preferable to have larger projections  182  and corresponding openings  140 , illustrated as being larger than the projections  170  at the back ends  108 , 162 , to prevent separation of the main body  102  from the cap  102  during side loads on the strain relief boot  304 , particularly in the middle portion area. The direction of the projections  182  and corresponding openings  140  also helps in this regard. The cap  104  also has a transitional area  190 , which corresponds to the transitional area  150  of the main body  102 . 
     As a user assembles the two-piece spring push  100 , see  FIG. 1 , the main body  102  has the optical fibers  300  in the groove  130  with the optical ferrule secured to the optical fibers to the right in  FIG. 1 . The cap  104  is then aligned with the center projection  180  in the opening  142  and the projections  182  are inserted into the openings  140 . The back end  162  of the cap  104  is then rotated downward thereby further inserting the projections  182  into the openings  140 . At this point the transitional areas  150 , 190  allow the smooth rotation of the cap  104  relative to the main body  102 . The projections  170  are then aligned with the openings  118 , but as the back end  162  is rotated relative to the main body, the back portion of the projections  170  make contact with the edge of the openings  118 . The user then snaps the back end  162  down and the chamfered portion  174  allows the projections to snap into the openings  118 . The cap  104  is then held to the main body  102  through the frictional interactions of the projections and the openings. As illustrated in  FIG. 4 , a crimp band  302  and a strain relief boot  304  are then applied over the back end of the two-piece spring push  100 , further securing the cap  104  to the main body  102 . 
     Another embodiment of a two-piece spring push  400  is illustrated in  FIG. 6 . In this embodiment, the two-piece spring push  400  has a main body  402  and a cap  404  that frictionally connects to the main body  402 . The main body  402  and a cap  404  in this embodiment have two of the projections and two of the openings in opposing structures. The projections and openings at the front end  406  of the cap  404  are reversed. That is, the projections  408  are on the middle portion  410  of the main body  402  and the openings  412  are at the front end  406  of the cap  404 . Similarly the projections and openings at the back end of the two-piece spring push  400  could also be reversed, although given the similarity in the back ends of the pieces of the two-piece spring push  400 , the reversal is relatively simple. 
     It will be apparent to those skilled in the art that various modifications and variations can be made to the present invention without departing from the spirit and scope of the invention. Thus it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.