Abstract:
The present invention relates to an opto-electronic system including an opto-electronic module and a cage assembly for electrically connecting and securing the electronic module to a host computer device. Corresponding mechanical features are provided on the module and the cage assembly to prevent modules from being plugged into incompatible cage assemblies.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     The present invention claims priority from U.S. Patent Application No. 60/602,064 filed Aug. 17, 2004, which is incorporated herein by reference. 
     
    
     TECHNICAL FIELD  
       [0002]     The present invention relates to an optical module/cage system for ensuring that only the proper optical module is inserted into a corresponding cage assembly, and in particular to mechanical features on the cage assembly and/or the optical module that prevent the wrong optical module from being inserted into the system&#39;s cage assemblies.  
       BACKGROUND OF THE INVENTION  
       [0003]     A conventional opto-electronic system, illustrated in  FIG. 1 , includes an opto-electronic module  1 , e.g. a transceiver, and a cage/guide rail assembly  2 . The module  1  includes an optical connector  3  at a front end thereof, and an electrical connector  4  at a rear end thereof. Typically, the optical connector  3  includes a pair of ports for receiving a first optical fiber to be optically coupled to a receiver optical sub-assembly (ROSA), and a second optical fiber to be optically coupled to a transmitter optical sub-assembly (TOSA). The TOSA and the ROSA are disposed adjacent one another on a module printed circuit board within a module housing  6 . For convenience, the electrical connector  4  is formed on an edge of the module printed circuit board.  
         [0004]     The cage/guide rail assembly is for mounting in a host computer device, and includes a faceplate  7  mounted on an edge of a host printed circuit board  8 , and a cage or guide rail  9  mounted on the host circuit board  8  extending from the faceplate  7 . An access hole  10  is provided in the faceplate  7  enabling the module  1  to pass therethrough into the cage  9 . An electrical connector  11  is mounted within the cage  9  for receiving the electrical connector  4 , and for transmitting electrical signals between the host computer device and the opto-electronic module  1 .  
         [0005]     Conventionally, as new multi-source agreement (MSA) transceiver systems were developed, the cage or rail assemblies for securing the optical module to a host computer system changed significantly, so there was no confusion over which transceiver fit into which cage/rail assembly. However, currently there is a desire to maintain some of the existing module and cage sizes or dimensions to enable some parts to be used in multiple product lines. Unfortunately, problems can arise when new transceiver modules are plugged into systems with existing non-compatible electrical connectors, and vice versa, when old transceiver modules are plugged into new cages with new non-compatible electrical connectors.  
         [0006]     An object of the present invention is to overcome the shortcomings of the prior art by providing a transceiver module/cage system that ensures transceiver modules can not be plugged into non-compatible cages.  
       SUMMARY OF THE INVENTION  
       [0007]     Accordingly, the present invention relates to an opto-electronic system comprising:  
         [0008]     an opto-electronic module including a housing and a first electrical connector, the housing including a groove therein; and  
         [0009]     a cage assembly for mounting on a host printed circuit board, the cage assembly including a faceplate, a cage, and a second electrical connector for mating with the first electrical connector, the cage assembly including a stop extending therefrom for preventing opto-electronic modules without the groove from becoming fully inserted into said cage assembly.  
         [0010]     Another aspect of the present invention relates to an opto-electronic system comprising:  
         [0011]     an opto-electronic module including a housing and a first electrical connector, the housing including a first camming surface; and  
         [0012]     a cage assembly for mounting on a host printed circuit board, the cage assembly including a faceplate, a cage, and a second electrical connector for mating with the first electrical connector, the cage assembly including a second camming surface extending therefrom for engaging the first camming surface, thereby preventing opto-electronic modules without the first camming surface from becoming fully inserted into said cage assembly. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]     The invention will be described in greater detail with reference to the accompanying drawings which represent preferred embodiments thereof, wherein:  
         [0014]      FIG. 1  is an isometric view of a conventional opto-electronic system;  
         [0015]      FIGS. 2   a  and  2   b  are isometric views of opto-electronic modules according to the present invention;  
         [0016]      FIG. 3  is a front view of a faceplate including various embodiments of the present invention;  
         [0017]      FIGS. 4   a  and  4   b  are isometric views of cages according to other embodiments of the present invention;  
         [0018]      FIG. 5  is an isometric view of a cage according to another embodiment of the present invention;  
         [0019]      FIG. 6   a  is an isometric view of an electrical connector according to another embodiment of the present invention;  
         [0020]      FIG. 6   b  is an isometric view of a opto-electronic module connected to the electrical connector of  FIG. 6   b;    
         [0021]      FIG. 7  is an isometric view of an opto-electronic module according to another embodiment of the present invention;  
         [0022]      FIG. 8  is an isometric view of an opto-electronic module according to another embodiment of the present invention;  
         [0023]      FIG. 9  is a front view of a faceplate according to another embodiment of the present invention;  
         [0024]      FIG. 10  is an isometric view of an opto-electronic module according to another embodiment of the present invention; and  
         [0025]      FIG. 11  is an isometric view of a cage according to another embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION  
       [0026]     With reference to  FIGS. 2   a  and  2   b , an opto-electronic module  21  according to the present invention includes the same basic elements as opto-electronic module  1 , i.e. an optical connector  23 , and electrical connector  24 , a ROSA, a TOSA, and a module printed circuit board. However, the module housing  26  includes a first mechanical feature, such as a groove  27   a  or  27   b  ( FIG. 2   b ). Preferably, the groove  27   a  (or  27   b ) is triangular in cross-section and extends longitudinally along the top of the housing  26  from the front end to the rear end of the module  21 ; however, other configurations are possible, e.g. along the sides or bottom, extending only a partial distance between the front and rear of the module, having other shaped cross sections, and having multiple grooves. Positioning the groove  27   b  along the corner of the module housing  26 , i.e. at the intersection of two perpendicular surfaces, e.g. the top and side walls, as in  FIG. 2   b , has manufacturing and structural advantages.  
         [0027]     FIGS.  3  to  5  illustrate various embodiments of the present invention in which different parts of a cage assembly include a second mechanical feature, e.g. a stop, for preventing an opto-electronic module (which otherwise has similar cross-sectional dimensions) without the first mechanical feature from becoming fully inserted into the cage assembly. With reference to  FIG. 3 , a faceplate  36 , with opening  37   a ,  37   b ,  37   c  and  37   d , includes the second mechanical feature in the form of projections or stops  38   a ,  38   b ,  38   c  and  38   d  extending into the openings  37   a ,  37   b ,  37   c  and  37   d , respectively. The projections  38   a ,  38   b ,  38   c  and  38   d  are designed to match the shape of the groove  27   a  (or  27   b ) provided in opt-electronic modules that are compatible with the cage assembly. As with the above groove  27   a  (or  27   b ), the projections can take any form, including a “w”  38   a , a “v”  38   b , a rectangle  38   c , and an angled corner  38   d  as long as the groove  27   a  (or  27   b ) is sized correctly to receive the projection and enable the module to pass unobstructed. Again the projections  38   a ,  38   b ,  38   c  and  38   d  can extend from any side of the openings  37   a ,  37   b ,  37   c  and  37   d.    
         [0028]      FIGS. 4   a  and  4   b  illustrate embodiments in which stop projections  48   a  and  48   b , respectively, extends from a cage  49 , which is mounted on host printed circuit board  50 . Preferably, the projections  48   a  and  48   b  extend from a front edge of the cage  49  into the opening  51  formed by the cage  49 , but can also be provided any where along the length of the cage  49  extending into the cavity created by the cage  49 . Again, the stop projections  48   a  and  48   b  are sized to be received in the groove  27   a  and  27   b , respectively, to enable the opto-electronic module  21  to pass into the cage  49  unobstructed, while preventing other opto-electronic modules with similar cross-sectional dimensions, but without the groove  27   a  or  27   b , from entering or becoming fully engaged therein.  
         [0029]     In an alternate embodiment illustrated in  FIG. 5 , the second mechanical feature is a stop projection or ridge  68  extending from the host printed circuit board  70  into the cavity defined by cage  69 . The ridge  68  prevents opto-electronic modules without a groove  27  in the bottom thereof from entering the cage  69 . As above, the ridge  69  can take any shape or form corresponding with the shape of the groove  27   a  or  27   b.    
         [0030]     With reference to  FIGS. 6   a  and  6   b,  a stop projection or ridge  78  can also be provided on an electrical connector  79  inside a cage (not shown). In this case a groove  87  is found in a rear end of the module housing  88 , in the underside of tail  89 . In this case the module housing  88  will be able to be partially inserted into the cage (not shown), but the electrical connectors will be prevented from becoming electrically coupled.  
         [0031]     As a further or alternate means for preventing the insertion of opto-electronic modules into incompatible cage assemblies a spring finger  90  is spring biased outwardly from opto-electronic module  91  into an abutment position for abutting a portion of the cage assembly and preventing insertion thereinto. The spring finger  90  can be a leaf spring normally biased outwardly at an acute angle from the housing  96 ; however, any rotatable finger having resilience or simply biased outwardly would suffice. An abutting surface  92  is formed in the outer free end of the spring finger  90  for abutting a cage assembly unless the spring finger  92  is manually or mechanically rotated into contact with the module housing  96 . The abutting surface  92  can be a portion of the outer free end of the spring finger  92  bent substantially perpendicular to the remainder thereof; however, a more complicated assembly is possible including a separate abutting surface fixed to the outer free end of the spring finger  92 . As above, the opto-electronic module  91  includes an optical connector  93 , a TOSA, a ROSA, a printed circuit board, and an electrical connector  94 . In the illustrated embodiment of  FIG. 7 , a recess  98  is provided in the module housing  96  for receiving the abutting surface  92  when the spring finger  90  is rotated into contact with the module housing  96 . With this arrangement, the opto-electronic module  91  can not be inserted into a regular cage assembly, i.e. without a second mechanical feature, without the additional step of rotating the spring finger  90  into an insertion position. The opto-electronic module  91  can also, but not necessarily, include a groove  97 , as hereinbefore described, to enable the module  91  to be inserted into cage assemblies with the second mechanical feature, e.g. the projection  38 ,  48 ,  68  or  78 .  
         [0032]     With reference to  FIGS. 8 and 9 , an alternative embodiment of an opto-electronic module  101  is illustrated including an optical connector  103 , an electronic connector  104 , and a TOSA, a ROSA and a module printed circuit board mounted within a housing  106 . A first mechanical feature, e.g. a groove  107 , can be provided to enable insertion of the module  101  into a compatible cage assembly, which would include a second mechanical feature, e.g. projection  38 ,  48 ,  68  or  78 . A spring finger  110  extends from opto-electronic module  101 , and includes an abutting portion  112  with an abutment surface  113 , and a camming portion  114  with a first camming surface  115 . The abutting portion  112  and the abutment surface  113  are similar to spring finger  90  and abutment surface  92 , respectively. The camming portion  114  and the camming surface  115  are connected to the abutting portion  112 , ideally formed out of the same spring finger  110 . The first camming surface  115  comprises a ramp positioned adjacent and parallel to the abutting portion  112 .  
         [0033]      FIG. 9  illustrates a faceplate  117  including second mechanical features, i.e. projections  118 , and second camming surfaces, i.e. tabs  119 , extending into openings  120   a ,  120   b  and  120   c . During insertion of a compatible opto-electronic module  101  into faceplate  117 , the second camming surface  119  will contact the first camming surface  115  and slide along the ramp formed thereby, gradually depressing the camming portion  114 , and consequently the abutment portion  112  until the spring finger  110  is rotated parallel and into contact with the surface of the housing  106  with the abutment surface  113  inserted into a recess  116 .  
         [0034]     For opto-electronic systems already including the first and second mechanical features, e.g. groove  107  and projection  118 , the tab  119  can be very small, i.e. less than the clearance between the housing  106  and the cage, and need not block entry of non compatible electro-optical modules; however, for systems without the first and second mechanical features, a tab  129  can be made somewhat larger to fulfill both functions, if the camming portion  114  with camming surface  115  are disposed within a groove  127  (see  FIG. 10 ). In this case, the cage assembly, e.g. the faceplate or the cage, only needs a single tab  129 , as in opening  120   c  of  FIG. 9 . The remaining elements of the opto-electrical module disclosed in  FIG. 10  are identical to those in  FIG. 8 .  
         [0035]     For opto-electronic systems without the first and second mechanical features, spring fingers  90  or spring fingers  110  and small tabs  119 , i.e. first and second camming surfaces, can be used to prevent or at least warn users of incompatible modules and cages. Opening  120   b  of  FIG. 9  illustrates a cage assembly, e.g. a faceplate, with a second camming surface alone. As with the projections  38 ,  48 ,  68  and  78 , the second camming surface can be provided on the faceplate (as illustrated) in  FIG. 9  or on any other part of the cage assembly, e.g. the cage ( FIG. 11 ), the host printed circuit board under the cage, or the electrical connector within the cage.  FIG. 11  illustrates a cage  129  mounted on a host printed circuit board  130  with a tab  139 , i.e. a second camming surface, extending from the cage  129  into cage area. The relative position of the spring fingers  90  and  110  and the tabs, i.e. the first and second camming surfaces, can be reversed, e.g. the spring fingers  90  and  110  extending from the faceplate  117  or the cage, while the tab or some other camming surface for rotating the spring finger  90  or  110  is found on the module  91  or  101 .