Patent Publication Number: US-9891387-B2

Title: Fiber optic adapter with enhanced alignment

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to U.S. patent application Ser. No. 12/546,311, filed Aug. 24, 2009, which will issue as U.S. Pat. No. 9,720,183 on Aug. 1, 2017, the subject matter of which is hereby incorporated by reference in its entirety. 
     FIELD OF THE INVENTION 
     The present invention relates generally to adapters for fiber optic connectors and specifically to adapters with enhanced alignment for multi-fiber push on (MPO) type connectors. 
     BACKGROUND OF THE INVENTION 
       FIG. 1  shows an example of the prior art, a typical MPO adapter  100 . The construction of the adapter  100  uses latches  102  that are integral to an inner shell  101 . The inner shell  101  is typically constrained within an outer shell  103  via ultrasonic welding. The assembly tolerances in such a design become critical in order to maintain proper connector mating alignment. This construction can impart a side load on an MPO connector if the tolerance stack-up is not tightly controlled. A side load can be caused by an out-of-tolerance part geometry, assembly tolerances, or ultrasonic welding variances. 
     Traditional MPO adapters do not allow mated connectors to adjust relative to the housing. They also utilize latches that are sectioned across the mid-line of the adapter. To create an opposing connector engagement, two such components must be assembled together, increasing the tolerance stack-up even more, and making it more cumbersome to control the alignment of mated connectors. 
     SUMMARY OF THE INVENTION 
     This application describes a fiber-optic adapter with enhanced alignment. The adapter has two opposing housing halves and two opposing floating connector latches. Each housing half has a channel for the mating connectors. The channels are configured to align when the two housing halves are secured together. The channels of the housing halves have pockets configured with a clearance fit, allowing the connector latches to float when the housing halves are secured together. 
    
    
     
       BRIEF DESCRIPTION OF FIGURES 
         FIG. 1  is a perspective view of a prior art MPO adapter; 
         FIGS. 2 and 3  are exploded perspective views of a first embodiment of an MPO adapter with enhanced alignment; 
         FIG. 4  is a perspective view of a floating connector latch to be used with the MPO adapter of  FIGS. 2 and 3 ; 
         FIG. 5  is an exploded perspective view of a second embodiment of an MPO adapter with enhanced alignment; and 
         FIGS. 6A and 6B  are perspective views showing an MPO connector being inserted into an MPO adapter with enhanced alignment. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       FIGS. 2 and 3  show a first embodiment of an MPO adapter  200  with enhanced alignment. The adapter comprises a pair of opposing housing halves  201 ,  202  and a pair of opposing floating connector latches  400 . 
     The opposing housing halves  201 ,  202  contain a channel  203  that is sized to accommodate an MPO connector (in one embodiment, the adapter dimensions can conform to TIA-604-5-B, Fiber Optic Intermateability Standard—Type MPO). The channels  203  are configured to align and form a longer channel when the opposing housing halves  201 ,  202  are secured together. The housing halves  201 ,  202  also have latch pockets  204  formed in opposite sides of the channel  203 . The latch pockets  204  are configured with a clearance fit, allowing the connector latches  400  to float within the channel  203  when the opposing housing halves  201 ,  202  are secured together. The channels  203  can also incorporate polarity keyways  205  (best shown in  FIG. 3 ). The opposing housing halves  201 ,  202  can be configured wherein the mating features have a rotational symmetry of 180 degrees along a longitudinal axis in order to allow the polarity keyways  205  to be aligned for either a straight through or a key up/key down orientation. 
     The opposing housing halves  201 ,  202  can have assembly pins  207  and assembly holes  208  to facilitate the mating of the housing halves  201 ,  202 . In the embodiment shown in  FIGS. 2 and 3 , the assembly holes  208  are located on diagonally opposite corners (on the same face) from each other and the assembly pins  207  are also located on diagonally opposite corners from each other. 
     The housing halves  201 ,  202  can also utilize flanges  206  to aid in seating an adapter into a panel or cassette opening and to also facilitate mating the housing halves  201 ,  202  together. 
     In the embodiment shown in  FIGS. 2 and 3 , the opposing housing halves  201 ,  202  can constitute a male housing half  202  and a female housing half  201 . The female housing half  201  has a pair of snap receiving areas  209  located on a top and bottom face of the housing half  201 . Each receiving area  209  can contain a lever-arm catch  210 . The lever-arm catch  210  can have a back-rake angle in order to allow an interference snap-fit to create a positive loading between the two housing halves  201 ,  202 . 
     The male housing half  202  has a pair of lever-arms  211  projecting from and perpendicular to a mating face  220  of the male housing half  202  along a top and bottom edge. The lever-arms have catch-slots  212  formed in them in order to engage the lever-arm catches  210  located in the receiving areas  209  of the female housing half  201 . This embodiment can also incorporate mating features on the flanges  206  such as interlocking fingers or dovetail joints in order to distribute the assembly load and decrease mating stresses on the lever-arm catch  210 . Locating the receiving areas  209  on opposite faces such as the top and bottom face as well as having the lever-arms  211  extend from opposite edges of the mating face gives the housing halves  201 ,  202  a rotational symmetry of 180 degrees, which allows for either a straight-through orientation or a key up/key down orientation. 
       FIG. 4  shows a floating connector latch  400 . The floating connector latch  400  has engagement features  401  formed at both ends. The engagement features  401  on the floating connector latch  400  span the distance between the corresponding retention notches  601  on the connector (see  FIG. 6A  for the connector retention notches  601 ). Incorporating the two opposing connector engagement features  401  into a single component (the floating connector latch  400 ) allows for tighter tolerances and control over the distance between the mated connectors&#39; mechanical reference planes, which results in more consistent contact mating pressure and performance. 
     The floating connector latch  400  also allows for the part material to be tailored to the mechanical strength required for optimum operation of the connector assembly. The floating connector latch  400  can be manufactured of a different material, polymeric or metallic, without impacting the assembly tolerances. The floating connector latch  400  design facilitates control of the material flow while molding to ensure mechanical strength and durability. The floating connector latch  400  can also have a long beam length to minimize strain on the latch during insertion and retraction of the connector which increases the adapter&#39;s overall strength and durability. 
     The floating connector latch  400  can also have a pair of stabilizing tabs  402  extending from a top and bottom edge of the latch  400  proximate to the center of the floating connector latch  400 . The tabs  402  engage pocket slots  213  (see  FIGS. 2 and 3  for the pocket slots  213 ) incorporated in the latch pockets  204  utilizing a clearance fit. This arrangement prevents the connector latches  400  from being rigidly attached to the housing halves  201 ,  202  and helps to control the mating distance of the connectors by allowing the connectors to move and adjust, in unison, relative to the housing due to strain (such as cable loading) without adversely affecting the optical alignment of the connectors. This arrangement also minimizes insertion loss by allowing some freedom in the movement of the connectors and reduces ferrule pin-to-pocket binding for better overall ferrule mating and improved side loading performance. 
       FIG. 5  shows an alternative embodiment for an adapter  500 . In the embodiment of  FIG. 5 , the housing halves  501  are identical in order to simplify manufacturing. Each housing half  501  has a receiving area  509 , with one or more lever arm catches  510 , a clip recess  517 , a lever-arm  511  with one or more arm-slots  512 , flanges  506  with assembly pins  507  located on diagonally opposite corners, assembly holes  508  also located on diagonally opposite corners, and flange tabs  516  and flange notches  515  incorporated into each of the flanges  506 . The housing halves  501  are arranged such that the two housing halves  501  can be assembled by “flipping over” (rotating 180 degrees about a latitudinal axis) one of the housing halves  501  and snapping the two housing halves  501  together. The lever-arm  511  and arm-slots  512  of each housing half will engage the receiving area  509  and lever-arm catch  510  of the other housing half  501 . The assembly pins  507  of each housing half  501  will engage the assembly holes  508  of the opposing housing half  501  and the flange tabs  516  of each housing half  501  will engage the flange notches  515  of the opposing housing half  501 . 
       FIG. 5  also shows an MPO metal adapter clip  600  for fastening the adapter  500  to a panel or cassette. The clip  600  can be a tool-formed spring steel component. The clip  600  generally forms a “staple” shape in which the “staple” shape defines a base  601  and a pair of legs  602 . Two panel retention latches  603  are formed on the legs of the clip for securing the adapter  500  to a panel or cassette. The retention latches  603  are arranged such that they deflect as the adapter  500  is passed through a panel opening and then spring back to lock the adapter  500  in place. The clip  600  can engage a clip recess  512  located on one or both of the housing halves  501  ( FIGS. 2 and 3  show an embodiment where the clip  600  is secured to the male housing half  202  of the adapter  200 ). 
       FIGS. 6A and 6B  show a standard MPO connector  600  being inserted into an assembled adapter  200 ,  500 . The engagement features  401  of opposing floating latches  400  engage the retention notches  601  of the connector in order to secure the connector in the adapter  200 ,  500 . As previously mentioned, the floating latches  400  span the length of the adapter  200 ,  500  and the distance between retention notches  601  of opposing connectors  600  when the connectors are inserted into both sides of the adapter. 
     The walls of the adapter  200 ,  500  parallel to the longitudinal axis can be flat in order to allow the adapters to be stackable. The adapters  200 ,  500  can also be sized to retrofit existing panel and cassette installs that utilize SC style connectors or LC duplex connectors in order to provide an upgrade path to 40/100 gig fiber installations. 
     Unlike single-piece MPO adapter designs, the latch and housing materials of the present invention can be different so that the design can be optimized from a performance, cost, and process perspective with greater flexibility. For example, the housing can be made of metal for shielding or improved strength characteristics while the latches could be plastic for flexibility. The latches can be made from a high performance engineering resin while the housing could be made of a lower performance, low cost resin to control costs. The two-piece design also avoids mold processing issues associated with single piece design. In particular, latch performance and reliability may be affected because of knit lines, voids, short shots, molded-in residual stress, and voids resulting from material flow restrictions due to part geometry in the latch area. The undesirable part alterations can impact mechanical performance, such as shortening the latch geometry, in order to process the part. The two-piece design allows the latch to be molded separately which greatly improves processing and eliminates these issues. 
     While particular embodiments and applications of the present invention have been illustrated and described, it is to be understood that the invention is not limited to the precise construction and compositions disclosed herein and that various modifications, changes, and variations may be apparent from the foregoing without departing from the spirit and scope of the invention as described.