Abstract:
A cable connector is provided that has a connector housing that is thin and takes the form of a wafer. Terminals are held within the housing and termination portions extend lengthwise from the terminals. The termination portions extend out from the housing for terminating bare conductors of signal wires to them. A grounding shield is provided that extends over the signal terminals from their contact portions at the front end of the connector to their rear termination portions. The grounding shield thereby provided a ground extent over the termination area that increases the electrical affinity of the signal wires to the grounding shield so as to reduce crosstalk and noise during operation at high frequencies. In one embodiment, the grounding shield includes a separate extension that is connected to the base grounding shield. In another embodiment, the grounding shield has a length sufficient to extend over the termination area.

Description:
REFERENCE TO RELATED APPLICATIONS  
       [0001]    This application claims priority of U.S. Provisional Patent Application No. 60/437,044, filed Dec. 30, 2002.  
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    The present invention relates generally to connectors used in high-speed and high-density cable connector assemblies, and more particularly to a cable connector that has an improved grounding shield.  
           [0003]    In the field of telecommunications and in other electronic fields, cable assemblies are used to connect one electronic device to another. In many instances, the cable assemblies have at one or more of their ends, a plurality of connector modules, each of which serves to connect a plurality of individual wires to an opposing connector, such as a pin connector. It is desirable to provide very high density pin counts while maintaining superior cross-talk performance. Proper selective grounding of certain terminals is required to provide increased data transfer.  
           [0004]    Structures for attaining these aims are known in the art, but tend to be bulky and require additional, valuable, empty unused area. Such a structure is shown in U.S. Pat. No. 5,176,538, issued Jan. 5, 1993, and is shown to include a connector having a plurality of slots and cavities with signal contacts being received within the cavities of the connector. A grounding shield is provided having a plurality of contacts in the form of spring fingers which are positioned to protrude into the unoccupied slots. These spring fingers serve as contact portions that contact selected terminal pins. In this construction, each connector has to be custom configured for each installation.  
           [0005]    In the connector shown in U.S. Pat. No. 4,826,443, issued May 2, 1989, the individual termination ends of the signal contacts of the connector extend rearwardly past a body of the connector to define a termination area. No grounding shield is shown or described as being used to cover the termination area in order to provide shielding throughout the termination portion of the connector. At higher frequencies that are used for data transmission, the potential for signal-disrupting crosstalk increases greatly and unless the entire signal contacts are shielded, the possibility of occurrence of crosstalk increases.  
           [0006]    The present invention is therefore directed to a novel and unique grounding shield for use with cable connector wafers, or modules, which overcomes the aforementioned disadvantages and which provides improved shielding throughout the length of the connector and in the termination area of the signal contacts.  
         SUMMARY OF THE INVENTION  
         [0007]    Accordingly, it is a general object of the present invention to provide an improved grounding shield for use with wafer connector modules which has a simple standard construction, and permits ease of assembly.  
           [0008]    Another object of the present invention is to provide a grounding shield for use with wafer connectors which does not increase the connector size or result in a decrease of pin density in an opposing, mating connector.  
           [0009]    Yet another object of the present invention is to provide a grounding shield of singular configuration that may be easily varied, as in its width, to accommodate as many grounding paths as desired.  
           [0010]    A still further object of the present invention is to provide a grounding shield that extends over the signal termination area of the cable connector from between the rear edge of a grounding shield of the connector and the grounding shield of the cables terminmated tot he connector, and an insulator that is interposed between the shield and the signal contact termination areas, the insulator having a thickness and a dielectric constant that may be varied so as to adjust the impedance of the cable connector in the termination area and without modifying the configuration of the connector.  
           [0011]    Yet one more object of the present invention is to provide a high-density cable connector with a grounding shield having a length sufficient to extend over a termination area of the signal contacts of the connector, the shield having a plurality of openings formed therein aligned with the signal contacts which define windows opening through the shield which facilitate the termination of the signal contacts of the connector, without altering the configuration of the connector.  
           [0012]    The present invention accomplishes these and other objects by way of its unique structure. In accordance with one principal aspect of the present invention, a connector is provided with an insulative housing with a defined body portion, the body portion including a receptacle defined therein that accommodates a plurality of conductive terminals, each of which has a contact assembly for contacting a conductive pin of an opposing connector. A conductive grounding shield that fits on the connector housing body portion partially encloses the terminals in the receptacle portion of the connector housing. The grounding shield may have a center tab that extends rearwardly between the signal contact termination portions. An insulative insert is provided that extends over the termination portions of the signal contacts and it preferably has a thickness that matches that of the housing grounding shield. A second grounding shield is applied over the insert and has a center tab that extends through an opening of the insert to make contact with the center tab of the connector housing center tab. The insert separates the signal contact terminations portions from the grounding shields.  
           [0013]    In another principal aspect of the present invention, the insert is preferably formed from a dielectric material and the material is chosen to have a dielectric constant that will form a desired impedance among the terminals and the grounding shield of the cable connector so that the impedance of the connector may be tuned through the termination area thereof.  
           [0014]    In yet another principal aspect, the present invention includes an electrical connector module having an insulative body portion with a series of conductive terminals disposed within the body portion. The connector has a grounding shield which lies upon the outer surface of the body portion and which includes a cover portion that extends in a first plane. The grounding shield has at least one depression formed therein that extends away from the cover portion thereof and into opposition with a selected one of the connector terminals. This depression includes a contact portion spaced away from the grounding shield cover portion that is supported in its extent by a portion of the grounding shield that is also drawn during the forming process.  
           [0015]    In the preferred embodiment, the depression contact portion or a tip thereof, extends within a second plane, different from and generally parallel to the first plane so that the grounding shield contact portion may easily abut one of the connector terminals. A dielectric insert is provided having one or more apertures formed therein that provide passages through which the depressions extent in their path of ground contact to selected terminals. The contact portions of the grounding shield are preferably joined to their corresponding opposing terminals, such as by resistance welding or the like.  
           [0016]    These and other objects, features and advantages of the present invention will be clearly understood through consideration of the following detailed description.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0017]    In the course of the following detailed description, reference will be made to the accompanying drawings in which:  
         [0018]    [0018]FIG. 1 is an exploded perspective view of one embodiment of a wafer connector with an extended grounding shield constructed in accordance with the principles of the present invention;  
         [0019]    [0019]FIG. 1A is a perspective view of the connector housing and cables, taken from a different orientation to show the termination area of the connector;  
         [0020]    [0020]FIG. 2 is the same view as FIG. 1, but illustrating the insert and grounding shield extension assembled to the connector housing;  
         [0021]    [0021]FIG. 3 is a top plan view of the connector of FIG. 2;  
         [0022]    [0022]FIG. 4 is a right side elevational view of the connector of FIG. 2;  
         [0023]    [0023]FIG. 5 is a perspective view of the connector of FIG. 2, with the outer insulative body molded thereto;  
         [0024]    [0024]FIG. 6 is a partially exploded view of an alternative embodiment of a connector housing constructed in accordance with the principles of the present invention and utilizing an integrated grounding shield;  
         [0025]    [0025]FIG. 6A is a perspective view of a terminal used in the connector of FIG. 6;  
         [0026]    [0026]FIG. 7 is a perspective view of the connector of FIG. 6, shown in an assembled condition;  
         [0027]    [0027]FIG. 7A is a side elevational view of the connector of FIG. 7 taken along lines  7 A- 7 A thereof.  
         [0028]    [0028]FIG. 8 is the same view as FIG. 7, but taken from the underside thereof;  
         [0029]    [0029]FIG. 9 is a top plan view of the connector of FIG. 8;  
         [0030]    [0030]FIG. 10 is a bottom plan view of the connector of FIG. 9;  
         [0031]    [0031]FIG. 11 is a perspective view of the grounding shield of FIG. 6; and  
         [0032]    [0032]FIG. 12 is a front end view of the connector of FIG. 7.  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0033]    [0033]FIGS. 1 and 1A illustrate an electrical connector element, or module  20 , which has a relatively thin profile and such a connector is commonly termed a “wafer” connector in the art. The connector module  20 , as is known in the art, has a primary housing  22  formed from an electrically insulative material which houses a plurality of conductive terminals  24 . These terminals  24  extend through the connector primary housing  22  in order to provide conductive paths between individual wires  26 , that are arranged near along a rear end of the primary housing  22 . The wires  26  are held within a  19  that may have (not shown) an inner braided wire shield that encompasses the two signal wires  26 . Typically, one such cable  19  will contain two individual signal wires  26 . The front end  32  of the primary housing  22  (and the module  20 ) that is adapted for insertion into an opposing backplane-style connector, such as a pin header (not shown) that includes a plurality of conductive pins arranged in rows between two sidewalls.  
         [0034]    The front end  32  of the connector  20  includes a plurality of pin-receiving passages  78 , which are best illustrated in FIG. 6 that are aligned with each internal terminal  24  of the connector and which permit the entrance of the pins of the opposing backplane connector to enter during engagement of the connector  20  and the backplane connector. The wires  26  that are terminated to connectors of the present invention typically include coaxial wires or pairs of wires that have a center conductor  29  (FIG. 1A) which are held in an outer jacket  52  and they may be surrounded by a grounding shield in the form of a braided wire shield, metallic film wrapper or the like and which may further include a drain wire  51  of the cable  19 . In either situation, both signal conductors and ground conductors enter the secondary connector housing  80  for termination (FIG. 5). In order to maintain the ground paths associated with these wires, the connectors  20 , and particularly their primary housings  22 , are provided with a grounding shield  31  that extends from near the front end  32  of the connector and which covers a portion of the connector housing  22  as shown in FIGS. 1-3.  
         [0035]    The grounding shield  31 , in order to maintain appropriate grounding paths should preferably make contact with selected terminals  24 . This grounding shield is illustrated best in FIG. 1A and it can be seen in include a planar body that extends between a shield front portion  62  that extends over the contacts of the terminals  24  and a rear portion  63  that is attached to the connector body portion  34  and which extends into the termination area  50 . In the prior art, this grounding shield did not extend over or into the termination area  50  which is the area where the conductors  29  and the drain wires  51  of the cables  19  are terminated to the termination portions, or tails  27  of the conductive terminals  24 . (FIG. 6A.) FIG. 1 illustrates the termination gap “G” that includes the termination area  50  and the area of attachment of the grounding shield  31  to the primary connector housing  22 .  
         [0036]    As illustrated best in FIG. 6, the primary connector housing  22  includes a body portion  34  and two sidewall portions  36 ,  38  that extend away from the housing body portion  34  toward the forward end  32  of the connector  20  for a preselected extent. These sidewalls  36 ,  38  and the body portion  34 , cooperatively define a hollow, or recessed, receptacle area  40  (FIG. 6) in the connector housing  22 . This receptacle area  40  houses a plurality of conductive terminals  24 , and particularly the contact portions  25  thereof as best illustrated in FIGS. 7 &amp; 10.  
         [0037]    Returning to FIG. 1, it can be seen that the grounding shield  31  extends over a portion of the primary housing  22  and may include a series of slotted openings  60  that receive raised bosses  61  of the primary housing  22 . The bosses  61  and openings  60  are sized so as to provide an interference fit. The remaining body of the grounding shield  31  that interconnects the shield front portion  62  to the shield rear portion  63  is not shown in FIG. 1 because it is embedded in the rear portion of the primary housing  22 . This embedding may be accomplished in ways well known in the art, such as by insert molding, overmolding or the like. The grounding shield  31  in the final connector as shown in FIG. 5 is substantially embedded, or encased in an insulative material that makes up the secondary housing  80 . The secondary housing  80  is molded over the termination gap G (FIG. 1) to fill that space and to also connect the primary housing  22  to the wire clamp  69  and thereby form an integrated connector module  20 .  
         [0038]    As illustrated best in FIG. 1A, the grounding shield  31  has two sets of grounding tabs  64 ,  65 . The smaller of the two grounding tabs  64  are used to provide a termination surface to the drain wires  51  of the cables, while the larger of the two grounding tabs  65  is preferably located in the center of the array of wires (FIG. 1A) and it extends rearwardly. The open termination area shown in the drawings typically ranges from between about 0.1 to about 0.25 inches. At this small dimension, and with the close spacing of the free wire ends, the center grounding tab  65  is usually provided to prevent unintended crosstalk between the signal wires within each of the connectors, or “wafers” as well as between adjoining connectors/wafers. However, it has been found by us that providing more shielding over the termination area reduces the likelihood of crosstalk. The additional ground increases the electrical affinity between the signal wires and the ground.  
         [0039]    In order to provide the desired additional ground for affinity with the signal wires, a second ground plate  70  is provided that covers the termination area  50  of the termination gap G and the second ground plate preferably extends, as best illustrated in FIG. 2, from the rear edge  67  of the grounding shield  31  to the forward edge  68  of the wire carrier, or clamp  69 . Although the drain wires  51  of the cables  19  are attached to the grounding tabs  64  of the first grounding shield  31 , which in turn is connected to the second grounding shield  70  to provide complete ground continuity, such continuity may be established by other means. For example, the rear edge of the second grounding shield  70  may be attached to the inner braided shields or whatever shielding is used with the cables  19 , such as by soldering or clamping, while the front end of the second grounding plate makes contact with the rear portion  63  of the connector housing grounding shield  31 .  
         [0040]    A separate bridging member  73 , formed from an insulative material, is also preferably provided in order to prevent unintended shorting contact from occurring with the termination portions of the signal terminals. In this regard, the insulative bridging member  73  has a length that is less than that of the second grounding plate  70  so that the front edge of the second ground plate  70  may make contact with the rear portion  63  of the connector grounding shield  31 .  
         [0041]    The bridging member preferably has an opening, or window  74  as shown that permits the passage of a contact tab  72  formed within a slot  71  of the second grounding shield. This contact tab  72  extends down through the opening and into contact with the grounding shield  31 , and preferably the center grounding tab  65  thereof, and most preferably along the flat portion of the grounding tab  65  that extends between the two sets of cables. This contact is made within the plane of the termination of the signal and drain wires and is desirable to provide a complete ground circuit extending from the over the terminal contact portions  25  to over the termination area  50  and even a bit further rearward of that, to over the encased portion of the cables that project just forwardly of the wire clamp  69 . In other words, the second grounding shield  70  bridges the termination area  50  between the connector grounding shield  31  and the shielding of the cable  19  within the confines of the termination gap G.  
         [0042]    [0042]FIG. 5 illustrates the connector after it has been subjected to overmolding and illustrates a secondary housing  80  molded over the wire clamp  69 , the free ends of the cables  19  and the rear part of the primary housing  22 . This secondary housing  80  is insert molded or overmolded the connector  20  shown in FIG. 2. Portions of it will engage the raised bosses  61  to which the grounding shield  31  is attached. The secondary housing also serves to encase the grounding shield  31  and the second grounding shield  70 . The bridging member  73  may be formed of an engineered dielectric, that is, one that has a specific dielectric constant in order to increase the electrical affinity between the second grounding shield  70  and the signal wires. Suitable dielectrics for use as the bridging member  73  may include LCP (liquid crystal polymer) and PTFE (teflon). Although the bridging member is shown in the drawings as having a significant thickness as if it were a molded member, it will be understood that the bridging member  73  may be formed from a thin film so long as it provides the necessary insulating function. In this manner, the impedance of the connector  22  may even be tuned throughout the termination area  50  by way of the thickness and dielectric material from which the bridging member is formed.  
         [0043]    [0043]FIG. 6 illustrates another embodiment of an improved connector  100  with an integrated grounding shield that is constructed in accordance with the principles of the present invention. In this embodiment, the terminals  24  may be initially formed with a positioning block  102  so that the contact portions  24  of the terminal project from one side of the positioning block  102 , and their termination tails  27  project from another, opposite side of the positioning block  102 . The terminal contact portions  25  are received within the receptacle area  40  of a nose portion  104  of the connector. (FIG. 7.) A single, extended length grounding shield  110  is provided which has front, middle and rear portions  111 ,  112 ,  113 . The front portion  111  of the shield  110  extends over a portion of the receptacle area  40  and is partially received within a slot  105  of the housing nose portion  104  so that its front edge, particularly tabs  115  thereof extend forwardly to cover the full extent of the terminal contact portions  25 . (FIG. 9.)  
         [0044]    The extended shield  110  also preferably includes slotted openings  60  that engage bosses  61  formed on one surface of the positioning block  102 . The shield  110  also preferably includes other engagement openings  117  that engage, typically in an interference fit, raised bosses  120  that are formed as part of the nose portion  104 . Another opening  116  is also preferably provided to fit over the polarizing key  200  formed on the connector body. (FIG. 8.)  
         [0045]    The rear portion  113  of the grounding shield  110  has a pair of U-shaped slots  125  that define grounding tabs  126 . The drain wires of the cables are attached to these grounding tabs  126 , and the tabs  126  preferably extend within the plane of the grounding shield  110  and a clearance is provided for access to them for terminating the drain wires to them. The drain wire grounding tabs  126  are spaced apart from and preferably lie in a different plane that the terminal termination tails  27  as shown best in FIG. 7A. In this regard, the rear portion  113  of the grounding shield  110  may be formed in a step-like configuration, which is best illustrated in FIGS. 6, 7A and  11 . Not only does the step  130  facilitate access and termination, but it also permits the rear edge  131  of the shield  110  to engage a rear portion of the connector assembly, such as a wire clamp, or carrier (not shown) of the style shown at  69  in FIGS. 1-5, or to engage the inner braided shield of the cables  19  as shown in phantom in FIG. 7A. In this regard, this embodiment of the invention differs from the earlier embodiment discussed above in that the tab member at the rear edge of the shield  110  extends completely widthwise between opposite sides of the shield  110  in contrast to the earlier embodiment where the tab member  72  has a lesser width and extends only between two sets of the cables.  
         [0046]    While the particular preferred embodiments of the present invention have been shown and described, it will be obvious to those skilled in the art that changes and modifications may be made without departing from the teachings of the invention.