Patent Publication Number: US-6988834-B2

Title: Fiber optic connector module

Description:
This application is a continuation of application Ser. No. 10/279,675 filed Oct. 24, 2002, now U.S. Pat. No. 6,811,322. 

   FIELD OF THE INVENTION 
   This invention generally relates to the art of fiber optic transmission and, particularly, to a fiber optic connector module. 
   BACKGROUND OF THE INVENTION 
   Fiber optic connectors of a wide variety of designs have been employed to terminate optical fiber cables and to facilitate connection of the cables to other cables or other optical fiber transmission devices. A typical fiber optic connector includes a ferrule which mounts and centers an optical fiber or fibers within the connector. The ferrule may be fabricated of such material as ceramic. A ferrule holder or other housing component of the connector embraces the ferrule and may be fabricated of such material as molded plastic. A spring may be disposed within the housing or ferrule holder such that the ferrule is yieldably biased forwardly for engaging another fiber-mounting ferrule of a mating connector device. 
   A pair of fiber optic connectors or a connector and another optical fiber transmission device often are mated in an adapter which centers the fibers to provide low insertion losses. The adapter couples the connectors together so that their encapsulated fibers connector end-to-end. The adapter may be an in-line component, or the adapter can be designed for mounting in an opening in a panel, backplane, circuit board or the like. 
   Various problems continue to be encountered in designing fiber optic connector assemblies or other connector assemblies, including applications involving backplanes, motherboards, daughterboards and the like. U.S. Pat. No. 6,361,218, dated Mar. 26, 2002, which is assigned to the assignee of the present invention and which is incorporated herein by reference, shows a fiber optic connector module which is a very simple design and solves some of the problems of the prior art. However, problems still exist in aligning the ferrules of mating fiber optic connectors in adapters or other fiber optic connector devices. Specifically, if a fiber optic connector module is tilted or skewed within its fiber optic connector, even to a small extent, the ferrule which is fixed within the module will tilt or skew therewith. Therefore, the flat mating face at the front end of the ferrule will be at an angle to the flat mating face of the ferrule of the mating connector, and transmission losses may occur. The present invention is directed to solving these problems by allowing the ferrule to tilt relative to the module housing and, thereby, maintain a flush front face abutment of the ferrule with the ferrule of the mating connector. 
   SUMMARY OF THE INVENTION 
   An object, therefore, of the invention is to provide a new and improved fiber optic connector module of the character described. 
   In the exemplary embodiment of the invention, the fiber optic connector module includes a ferrule terminated to at least one optical fiber. The ferrule includes a forwardly facing latch surface and a rearwardly facing abutment surface. The ferrule is mounted in a manually manipulatable housing which includes a front portion encapsulating the ferrule and a rear portion extending rearwardly of the front portion for manual grasping by an operator. The front portion has an open front end through which the mating end of the ferrule projects, and an open rear end through which the optical fiber extends. Latch means are provided on the front portion of the housing engageable with the forwardly facing latch surface on the ferrule for holding the ferrule encapsulated in the housing. A forwardly facing abutment surface engages the rearwardly facing abutment surface on the ferrule. The forwardly facing abutment surface on the housing is convexly rounded so that the ferrule can tilt relative to the housing. 
   According to one aspect of the invention, the ferrule includes an outwardly projecting peripheral flange, and the forwardly facing latch surface is defined by a front edge of the flange. The latch means is provided by a pair of latch arms engageable with the front edge at opposite sides of the ferrule. The rearwardly facing abutment surface is defined by a rear edge of the flange. In the preferred embodiment, a pair of the convexly rounded, forwardly facing abutment surfaces are provided at opposite sides of the housing engageable with the rear edge of the peripheral flange. 
   Other features of the invention include the convexly rounded abutment surface being provided on a flexible arm past which the ferrule is inserted into the housing through the open rear end thereof. In addition, the housing defines a front-to-rear axis extending between the front and rear portions thereof. The rearwardly facing abutment surface on the ferrule is a generally flat surface extending transversely of the axis. 
   Other objects, features and advantages of the invention will be apparent from the following detailed description taken in connection with the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The features of this invention which are believed to be novel are set forth with particularity in the appended claims. The invention, together with its objects and the advantages thereof, may be best understood by reference to the following description taken in conjunction with the accompanying drawings, in which like reference numerals identify like elements in the figures and in which: 
       FIG. 1  is a perspective view of a mating connector assembly, with at least one of the connectors embodying the fiber optic connector modules of the invention; 
       FIG. 2  is a perspective view of the mating connector assembly in  FIG. 1 , in mated condition; 
       FIG. 3  is a perspective view of one of the fiber optic connector modules of the backplane connector assembly; 
       FIG. 4  is a perspective view of the housing of the connector module of  FIG. 3 ; 
       FIG. 5  is a perspective view showing the assembly procedure of the module of  FIG. 3 ; 
       FIG. 6  is a side elevational view of the connector module in assembled condition; 
       FIG. 7  is a view similar to that of  FIG. 6 , showing the ferrule tilted in one direction relative to the module housing; and 
       FIG. 8  is a view similar to that of  FIG. 7 , with the ferrule tilted in the opposite direction. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Referring to the drawings in greater detail, and first to  FIGS. 1 and 2 , the invention is embodied in a mating connector assembly, generally designated  10 , which includes a backplane connector assembly, generally designated  12 , mateable with a daughterboard connector assembly, generally designated  14 . The backplane connector assembly is mounted in an aperture  16  in a substrate, panel or backplane which, in the illustrated embodiment, is a printed circuit board. Specifically, backplane  18  can be considered the “motherboard” herein. The daughterboard connector assembly is mounted on a top surface of a second printed circuit board  20  which is considered the “daughterboard” herein. 
   Backplane connector assembly  12  includes an adapter, generally designated  22 , which is mounted in aperture  16  in motherboard  18 . Four fiber optic connector modules, generally designated  24 , are inserted into adapter  22 , through aperture  16 , from the front of backplane  18 . Each fiber optic connector is terminated to a multi-fiber cable  26 . Each cable is a flat or “ribbon” cable having a plurality of optical fibers. The invention herein is incorporated in connector modules  24 , as will be described in detail hereinafter. 
   After daughterboard connector assembly  14  is mounted on daughterboard  20 , four fiber optic connector modules, generally designated  28 , are inserted into the back of the connector housing. Each module  28  is terminated to a flat, multi-fiber cable  30  similar to fiber optic cables  26 . Backplane connector assembly  12  and daughterboard connector assembly  14  are mateable in the direction of arrows “A” ( FIG. 1 ) to a mated condition shown in  FIG. 2 , wherein the fibers of cables  26  and  30  are functionally connected. Latches  32  on opposite sides of adapter  22  engage latches  34  on opposite sides of the daughterboard connector assembly to hold the connector assemblies in mated condition as shown in  FIG. 2 . 
     FIG. 3  shows one of the fiber optic connector modules  24  which are inserted into adapter  22  as described above. Specifically, each module  24  includes a ferrule  36  terminated to one of the multi-fiber cables  26  with ends  26   a  of the fibers exposed at a mating face  36   a  of the ferrule. The ferrule includes a pair of alignment holes  36   b  opening at mating face  36   a . The ferrule is captured by a manually manipulatable housing, generally designated  48  ( FIG. 4 ), which includes a front portion  38   a  which actually captures the ferrule, and a rear portion defined by a pair of laterally spaced arms  38   b  that are graspable between an operator&#39;s finger. Ferrule  36  has a peripheral flange  36   c . Front portion  38   a  of housing  38  includes a pair of forward latch hooks  38   c  on two opposite sides of the housing and a pair of flexible latch arms  38   d  on the other two opposite sides of the housing. A chamfered latch boss  38   e  is formed on the outside of each laterally spaced arm  38   b  for latching the ferrule within adapter  22  by means of latch means within the ferrule but not visible in the drawings. The manually graspable arms include serrations  40  on the outsides thereof to facilitate manual grasping thereof. 
     FIG. 5  shows that ferrule  36  is insertable into housing  38  of connector module  24  in the direction of arrow “B”. The ferrule moves within channels  38   f  inside arms  38   b  and through an open rear end  38   g  of front portion  38   a  of the housing. The ferrule becomes latched in a position projecting out of an open front end  38   h  ( FIG. 4 ) of the housing and is locked in the position shown in  FIG. 3  by forward latch hooks  38   c  and flexible latch arms  38   b  engaging opposite sides of flange  36   c  of the ferrule. 
   Specifically, housing  38  of module  24  is hollow or open-ended as defined by open front end  38   h  ( FIG. 4 ) and open rear end  38   g  ( FIG. 5 ). The housing, thereby, defines a front-to-rear axis  44  through the center of the housing. When ferrule  36  is assembled in the housing, flange  36   c  of the ferrule defines a forwardly facing edge  46  which forms a forwardly facing latch surface for engagement by forward latch hooks  38   c  of the housing. The flange has a rear edge  48  which forms a rearwardly facing abutment surface engageable by the fronts ends of flexible latch arms  38   d  of the housing. Peripheral latch surface  46  and peripheral abutment surface  48  extend generally transversely of axis  44 . 
   The invention contemplates that housing  38 , and particularly the front ends of flexible latch arms  38   d , be provided with a unique forwardly facing abutment surface  50  for engaging the rearwardly facing abutment surface  48  on the ferrule. Specifically, referring to  FIG. 6  in conjunction with  FIGS. 3–5 , it can be seen that forwardly facing abutment surface  50  is convexly rounded as it faces the straight or transverse abutment surface  48  of ferrule  36 . This allows the ferrule to tilt relative to housing  38  in the event that the housing somehow is angled or skewed when presenting front mating face  36   a  of the ferrule to the front mating face of a ferrule of a complementary mating connector. 
   The tilting movement of ferrule  36  relative to housing  38  is shown in  FIGS. 7 and 8 . In  FIG. 7 , it can be seen that the ferrule has tilted or rotated about convex surface  50  in the direction of arrow “C”. In  FIG. 8 , ferrule  36  has been tiled in the opposite direction relative to housing  38  in the direction of arrow “D”. These depictions of  FIGS. 7 and 8  clearly show how the ferrule can tilt or rock back and forth as its abutment surface  48  rolls back and forth over convexly rounded abutment surface  50  at the front ends of flexible latch arms  38   d . In other words, there is a sort of tilting floating movement of the ferrule relative to the housing to accommodate misalignments when the connector module is mated with a complementary mating connecting device. 
   Finally, while the invention has been shown and described herein in relation to fiber optic connector modules  24  used in adapter  22  ( FIGS. 1 and 2 ) of backplane connector assembly  26  of mating connector assembly  10 , the connector modules can be used in a wide variety of applications other than the assembly shown in  FIGS. 1 and 2 . 
   It will be understood that the invention may be embodied in other specific forms without departing from the spirit or central characteristics thereof. The present examples and embodiments, therefore, are to be considered in all respects as illustrative and not restrictive, and the invention is not to be limited to the details given herein.