Abstract:
A connector provides mechanical strength and impedance-conforming coupling between conductors in a cable and conductors on a circuit board. The conductors in the cable and the circuit board carry differential signals. The connector is comprised of a dielectric plug that has conductive terminals installed in it which comprise an electrical triad. A dielectric inner body has at least one triplet of three conductive terminals that extend into corresponding slots of the dielectric plug. The dielectric inner body has latching arm slots that receiving a latching arm of a mechanical coupling link member. A protective cover extends over a wire management support member and the dielectric inner body portion and at least partially over the dielectric plug member. The protective cover has retention openings that engage an actuator leg of a latching member. The protective cover also has at least one bias leg recess, for receiving a bias leg of the latching member. A latching member has bias legs that extend into the bias leg passages of the dielectric plug member. The latching member locks the dielectric plug member, the dielectric inner body and the protective cover together.

Description:
REFERENCE TO RELATED APPLICATIONS  
       [0001]    This application claims priority from U.S. Provisional Patent Application Serial No. 60/367,953, filed Mar. 27, 2002. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    The present invention relates generally to connectors used to connect together differential signal circuits, and more preferably to a connector assembly for connecting together differential signal circuits that incorporates a latching signal circuits that incorporates a latching assembly to provide increased retention forces to maintain the connector assembly together in a metal state.  
           [0003]    Connectors used in differential signal applications are known in the art. Some of these connectors arrange their terminals in a signal-signal-ground pattern. However, patterns such as these have problems with controlling the impedance of the connector through the mating and termination regions of the connectors. The impedance of the terminals can be controlled by using a triangular pattern, referred to as a “triad” in U.S. Pat. No. 6,280,209, issued Aug. 28, 2001 to the assignee of the present invention. In these triads, two differential signal terminals and an associated ground terminal and arranged are arranged in a triangular pattern so that the terminals are positioned at the apexes of the triangular pattern. Using a number of these triads and inverting them so that some triangular patterns are upright and the intervening triangular patterns are turned upside down, or inverted is one way of increasing density of the terminals in connectors. This arrangement is disclosed in copending International Patent Application No. PCT/US02/18372, filed Jun. 11, 2001 and also owned by the assignee of the present invention.  
           [0004]    However, in the connectors described in these patent or applications, the manner of engagement utilized is either housing-to-housing or shield-to-shield frictional contact. Although this sufficient to retain the connectors together in normal connections, it is not sufficient to retain the connectors together under rough connection and disconnection cycles, or bear the weight of heavier cables that contain multiple sets, such as six or more, of differential signal cables, each with their own associated ground. Retention of the connectors is important to maintain the connectors and their terminals together.  
           [0005]    Accordingly, the present invention is directed to a differential signal connector assembly that uses “triad” terminal arrangements and which has increased retention capabilities over the prior art.  
         SUMMARY OF THE INVENTION  
         [0006]    It is a general object of the present invention to provide an improved differential signal connector that uses a plurality of “triads” of terminals for connecting with a mating connector, and which utilizes a latching system to retain the connectors in a mater condition after engagement.  
           [0007]    Another object of the present invention is to provide a connector assembly for connecting a cable to a circuit board in which the connector assembly includes first and second connectors, the first connector being terminated to a plurality of differential signal wires (and grounds) in the cable and the second connector being terminated to a differential signal circuits on a circuit board, the two connectors of the assembly having a plurality of conductive terminals arranged in at least two rows that extend widthwise of the connectors, the terminals being arranged in distinct “triads” or triplets with two differential signal terminals and one associated ground terminal arranged at apexes of imaginary triangles, the imaginary triangles of which may be arranged in an alternating, or inverted sequence within the connectors and the first connector including at least two latching members disposed therein and extending lengthwise along the first connector housing body, the latching members being engageable with stop surfaces on the second connector.  
           [0008]    Yet another object of the present invention is to provide the latching members in the form of two elongated latching arms, each of the latching arms having a retention end that engages one or more housing, or body, portions of the second connector and a latching end disposed along a latching arm that projects forwardly of the retention end, the latching end including, in one embodiment, a hook-shaped latch that is received within a slot formed in the first connector, the latching arms extending alongside the first connector body portion into the terminal mating area thereof, but fully enclosed with an exterior shell or shield so as to prevent damage thereto.  
           [0009]    A still further object of the present invention is to provide a latching member having a cantilevered latching arm that extends forwardly alongside its connector body portion, the latching arm terminating in a latching hook and further having a withdrawal stop member formed thereon intermediate between the latching hook and the retention end of the latching member.  
           [0010]    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  
       [0011]    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:  
         [0012]    [0012]FIG. 1 is a top plan view of three connector assemblies constructed in accordance with the principles of the present invention;  
         [0013]    [0013]FIG. 2 is a perspective view of the connector assembly of FIG. 1 with the cable connectors removed from the circuit board connectors;  
         [0014]    [0014]FIG. 3 is an exploded view of one of the circuit board (receptacle) connectors of the connector assembly of FIG. 1;  
         [0015]    [0015]FIG. 4 is an exploded view of the leaf housing of the circuit board connector of claim  3 ;  
         [0016]    [0016]FIG. 5A is a diagrammatic view of the terminal arrangement of the receptacle connector in a surface mount configuration;  
         [0017]    [0017]FIG. 5B is a diagrammatic view of the terminal arrangement of the receptacle connector in a through-hole configuration;  
         [0018]    [0018]FIG. 6 is a perspective view of a plug (cable) connector used in the connector assembly of FIG. 1;  
         [0019]    [0019]FIG. 7 is an exploded perspective view of the components of the plug connector of FIG. 6;  
         [0020]    [0020]FIG. 8 is a perspective view of the plug connector housing body portion with its terminals in place and with the latching members in place therein;  
         [0021]    [0021]FIG. 9 is a front elevational view of a plug connector of FIG. 6;  
         [0022]    [0022]FIG. 10 is a sectional view of the plug connector illustrating the positioning of the latching member within the plug connector body portions and enclosed by the plug connector shield;  
         [0023]    [0023]FIG. 11 is a perspective sectional view of the plug connector mated together with an opposing receptacle connector; and,  
         [0024]    [0024]FIG. 12 is a top plan detail view of the plug and receptacle connectors of the connector assembly mated together. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0025]    The present invention is directed to a differential signal connector, particularly useful in SCSI applications with improved impedance characteristics and with improved connector retention characteristics. As shown in FIG. 1, a circuit board  50  has a plurality of circuit board connectors  51 , shown as receptacle connectors with the convention “receptacle” meaning that the connector has a plurality of terminals supported thereon in an opening, or cavity, that mate with a plurality of opposing terminals that are supported on a housing that is insertable into and removable from the receptacle connector.  
         [0026]    Three such receptacle connectors  51  are shown mounted to an edge  52  thereof. The edge  52  of the circuit board  50  may be positioned in an electronic device such as a computer or other similar electronic device. Opposing connectors  53  are provided which are mateable with the receptacle connectors  51  and these connectors  53  are terminated to cables  54  and the termination area  55  of which are enclosed within a protective flexible sheath, or cover  56 , that protects the termination area in a manner that is known in the art. The receptacle connectors  51  typically extend past an edge of the circuit board  50  and the mating portions thereof typically project through a wall, or panel of a housing  130  (shown in phantom) that encloses the circuit board  50  and its components.  
         [0027]    [0027]FIG. 2 illustrates the mating connectors  53  disengaged from their opposing receptacle connectors  51 . This figure illustrates the plug nature of the cable connectors  53  having a central plug, or other portion that supports conductive terminals thereon on which is insertable into the receptacle, or cavity of the circuit board connectors  51 . FIG. 3 is an exploded view of the circuit board, or receptacle connector  51 , and it illustrates the main components thereof, namely: an inner housing member or terminal support structure  60 , a shield member  61  that fits over and at least partially encircles a portion of the inner housing  60  and a rear or outer housing member  62 . This shield member  61  is preferably attached to appropriate ground circuits on the circuit board  50  by ground tabs  75 .  
         [0028]    The inner housing member  60  is preferably formed of two parts  63 ,  64  that are preferably molded from an insulative material, such as a dielectric plastic. Each of these parts  63 ,  64  may include a respective leaf portion  65 ,  66  that projects forwardly from a rear wall portion  67 ,  68 . These two leaf portions  65 ,  66  each support a plurality of conductive terminals  69  thereon in a particular fashion. These two housing parts  63 ,  64  each support, by way of their respective leaf portions,  65 ,  64  a single row of conductive terminals. The housing parts  63 ,  64  may be engaged with each other in a suitable fashion, such as by welding (plastics or ultrasonic) the two parts together, or providing them with interengaging holes  131  that receive corresponding opposing posts  132 .  
         [0029]    In order to deliver high speed performance at controlled impedance values, the terminals  69  are generally arranged in set of three, or as triads or triplets, which each terminal triplet or triad being connected to differential signal circuitry on the circuit board  50 . The structural essence of these triads/triplets are explained in U.S. Pat. No. 6,280,209, issued Aug. 28, 2001, to the assignee of this invention and the disclosure of which patent is hereby incorporated by reference herein. As stated therein and as shown diagrammatically in FIG. 9, these triads each preferably include a single ground terminal  70  and a pair of signal terminals  71 . The signal terminals  71  of each triad are dedicated to differential signals, e.g., signals having the same magnitude, but opposite polarities (+0.5v &amp; −0.5v) and the differential signal terminals are spaced apart from each other and supported on one of the leafs  66  while the associated ground terminal  70  is supported on the other leaf  65  and spaced apart from the signal terminals  71 . Likewise, the ground terminal of one triad is inverted with respect to the ground terminal of an adjoining terminal triad. In this manner, the ground terminal of the one terminal triad will be supported on the one leaf portion, while the ground terminal of an adjoining terminal triad will be supported by the opposite leaf portion  66 . This separation between the ground and the signal terminals occurs along two of the three extents of the terminals and is illustrated schematically in FIGS. 5 a  and  5 B. Each terminal of the circuit board connector  51  may be considered as having a flat contact portion “C” preferably in the form of a wide blade, a thin mounting portion “M” (shown in FIGS.  1 - 4  and  5 A as surface mounting feet) that extends horizontally in a plane that is spaced apart from the plane(s) in which the contact portions “C” lie, and a body portion “B” that interconnects the contact and mounting portions together. In the surface mount arrangement of FIG. 5A, the tails, or mounting portions M lie along the surface of the circuit board  50 , whereas in the through hole arrangement of FIG. 5B, the terminal tails M which are supported on different leaf portions  64 ,  65  are spaced apart from each other so that they may project through holes formed in the circuit board  50 .  
         [0030]    Returning to FIG. 3, the receptacle connector  51  includes an inner housing  60  that may be formed from two interfitting body portions  63 ,  64  that may snap, press fit or otherwise mate together to form the inner housing or body  60  of the connector  51 . As shown in FIG. 4, the contact portions “C” of the terminals are supported on the leaves, or blades  65 ,  66  of the body portions  63 ,  64  and the engagement between the two preferably occurs between or along the rear wall portions  67 ,  68  thereof. Once the body portions  63 ,  64  are assembled together, the rear or outer housing portion  62  (FIGS. 2 &amp; 3) may be molded to or over portions of the inner housing  60  so as to secure the body portions  63 ,  64  together and surround and/or isolate the terminals of the receptacle connector at least insofar as the body portions “B” thereof are concerned.  
         [0031]    In order to provide good engagement between the inner housing  60  and the rear, outer housing  62 , the body  134  of the rear outer housing  62  may be provided with openings  135  that may be considered as windows, or passage, which receive complementary-shaped lugs, or projections  136 , that are preferably formed as part of the inner housing  60 , and which are shown in FIG. 3 as being formed as part of the upper second part  63 . These lugs  136  are supported by intervening slots  137 . The rear outer housing  62  may be snap fit, or pressed, onto the inner housing  60 , or it may be molded together over the inner housing  60 .  
         [0032]    The side edges  75  of one of the housing blades  65  are preferably provided with notches, or recesses  76 , the purpose of which is explained in greater detail below. As stated above in the Summary section, the terminals  70 ,  71  are arranged along the housing blades  65 ,  66  in groups of three with the associated ground terminal  70  of each triad being supported on one of the housing blades while the two differential signal terminals  71  of the triad are supported on the other of the two housing blades. This sequence is alternated, or inverted, widthwise along the inner housing  60 .  
         [0033]    Turning now to FIGS. 6 and 9, this terminal arrangement sequence is repeated for the plug connector where two signal terminals are supported on alternating surfaces of the plug member  80  so that a series of imaginary triangles “T” are formed in an inverted fashion. Eight such terminal triads T 1 -T 8  are shown in FIG. 6 and the alternating sequence is clearly shown. The two center triads T 4 , T 5  need not be traditional triads of signal and ground, but may be other types of terminals, such as ones dedicated to power in and return or status information. The benefits and other structural details about such an inverted terminal triad arrangement are set forth in International Patent Application No. PCT/US02/18372, the disclosure of which is hereby incorporated herein by reference.  
         [0034]    As best seen in FIG. 7, the plug connector  53  includes an insulative inner body portion  81  that is preferably formed as two pieces  82 ,  83  and which support a plurality of elongated, conductive terminals  84  thereon. The terminals  84  have contact portions  85  on one end and termination portions  86  on the other end to which a plurality of differential signal cables  87  are terminated. These cables  87  may be held in place with an insulative wire management support member  88  that is in turn, received within an outer protective cover  56 . (FIG. 2.) The inner body portion  81  preferably has a plurality of slots  90  that receive single terminals  84  therein. Although this plug member  80  provides some retention force to the connector assembly, in certain applications, more retention force is desired, especially in situations as shown in the drawings where multiple differential signal cables are held within an exterior cable  54 , the diameter of which will typically equal or exceed 11 mm. This large size exerts a strain or pull out force on the plug connector when mated to the receptacle connector, due to its weight. In order to resist part of that force, the rear outer housing  62  may be provided with attachment legs  94  that extend out from, in a rearward fashion, the body of the rear housing  52 . These legs  94  may be hollow as illustrated in FIGS. 2 &amp; 3 to receive mounting screws, or bolts  95 , therein which extend through the circuit board  50  and which hold the two components together using nuts  96 .  
         [0035]    The inner plug member  81  engages an outer plug end  80  that has a mating portion  89  that projects from (forwardly) a rear portion  91  that engages the inner plug member  81 . The projecting mating portion is received within a corresponding opposing mating slot or receptacle of the circuit board connector  51 . Raised shoulders  92  are received within slots  93  disposed at opposing ends of the inner plug member  81 . Slots  90  are formed in the mating portion  80  and these slots receive the terminal  81  lengthwise, with one terminal being received within a single slot. The terminals  84 , as shown in the drawings, have a bent profile such that their contact portions  85  extend upwardly through the plug member mating portion slots  90 , as is known in the art. These raised profiles  85  will deflect slightly as they contact the opposing terminals of the receptacle connector.  
         [0036]    In an important aspect of the present invention, and as illustrated in FIGS. 7 and 8 and  10  and  11 , one of the two connectors, preferably the plug connector  53 , is provided with one or more latching members  100 , two of which are shown. These latching members  100  are secured to the inner housing  81  of the plug connector by way of retention or body portions  101  that have barbed retainer legs  102  or the like that extend therefrom. Two such legs  102  are shown extending from the retention portion  101  in opposite directions and are received within corresponding opposing passages  105 ,  106  that are formed in the plug member  80  (FIG. 10) and in the wire management member  88  (FIGS. 7 &amp; 11).  
         [0037]    Each latching member  100  is shown as having an elongated latching arm  110  that extends, in a cantilevered fashion forwardly of the retention portion  101  and forwardly along the inner body portions  81  and above the blade member  80 . The latching arms  110  extend through slots, or grooves  139 , formed along the ends of the plug mating member  80 , as best shown in FIG. 8. An upwardly protruding latch, in the form of a hook  112  is disposed at the forward, latching end of the latching member  100 . This hook  112  has rearward facing engagement face  113  that abuts in a confronting fashion, a stop or engagement surface  114  formed in a latching slot  116  formed in the outer shield  61 . (FIG. 11.) This slot  116  is aligned with the notches  76  of the inner housing  60  so that the latching member  100  may be inserted therein without fear of impinging or stuffing on an interval surface of the receptacle connector. The latching hook  112 , as shown in FIG. 8, extends alongside the projecting mating blade of member  80  and is preferably spaced rearwardly from the front face  80   a  (FIG. 8) thereof so that the latching will occur within the enclosed mating area of the connector and so the latch hook  112  will not be exposed and open to stubbing.  
         [0038]    An actuator lug  120  is preferably also formed on the latching arm  110  and extends outwardly and upwardly therefrom through an opening  125  formed in the outer conductive shell  126  of the plug connector  53 . This provides a means by which to release the latch hook  112  from its engagement with the opposing stop surface  114  of the connector slot  116  by which the user can depress the actuator lug and disengage the latch hook  112 . The outer conductive shell  126  is itself housed within the exterior, insulative sheath  56 , as shown in FIG. 6, and the sheath may be provided with an interior shoulder or projection  156  that is positioned so that it abuts against the actuator lug  120 . By pressing on these shoulder areas  156 , the user can depress the latching hook  112  out of engagement with the opposing mating connector  51 .  
         [0039]    The latching members  100  are preferably maintained above or below the level of the plug member  80  so as to better resist the disengagement forces that are likely to result from the dead weight of the cable or checking the connections for integrity. The use of the latching member  100  increases the positive retention force required to disengage the two connectors to resist approximately 30 lb. shock load and possibly higher.  
         [0040]    The latching members  100  are positioned and enclosed inside of the plug shield and/or housing as mentioned above so that they are protected and will not be susceptible to damage. The latching members  100  have their latching arms  110  preferably positioned above the horizontal insertion axis H of the connector mating portion to resist the typical pulling force that is exerted downwardly and outwardly. The latching members  100  serve to maintain the engagement between the two connectors and hence maintain the contact between the terminals of each triad. The latching members  100  and the windows or slots  116  are preferably either aligned with the longitudinal axis of the attachment legs  94  (FIGS. 11 and 112) of the receptacle connector  51 , or are offset therefrom a distance “D” that is preferably about 1 mm and no more than 3 to 4 mm. In this manner, the engagement of the terminals are reliably maintained within each triad.  
         [0041]    It will be understood that the invention may be embodied in other specific forms without departing from the spirit 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.