Abstract:
A cable connector having improved strain relief and cable retention qualities disclosed. A separate strain relief member includes a ferrule or anvil. This member is placed on a cable. The connector is then assembled and the shields are then attached to the connector parts, including the strain relief member. Latches are provided on a connector that mates with the cable connector. The latches engage the strain relief directly. In one embodiment, the latches engage lugs formed on the strain relief member. In another embodiment, the latches have a plurality of protrusions that engage openings in a facing side wall of the cable connector to aid in maintaining the connectors in mated condition, under forces imparted by the cable. The latches can be removed by inserting latch parts or tools into removal openings in side walls or at the top of the connector on which the latch is mounted. Alternatively, latches are mounted to the cable connector to engage latching elements on the mating connector. A mating connector housing is arranged to accommodate latches mounted thereon on the cable connector.

Description:
RELATED APPLICATIONS 
     This application is a continuation-in-part of application Ser. No. 08/941 824, filed Oct. 1, 1997 now abandoned. This application is based on provisional application Ser. No.60/076,064 filed Feb. 26, 1998 and entitled Cable Interconnection. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to electrical connectors and more specifically to cable connectors and cable interconnections, and especially to such cable connectors that are shielded. 
     2. Brief Description of Prior Developments 
     Cable connectors have been developed that employ shielding to maintain signal integrity during passage of high speed electrical signals. Such developments characteristically include strain relief mechanisms for providing strong attachment to the cable so that individual conductors remain secured to the terminals within the connector. 
     In addition, latching systems have been proposed for securing cable connectors to mating connectors, especially connectors that are mounted on the circuit boards or equipment with which the cable is to be associated. One such shielded cable connector with an associated latching arrangement is shown in International Application Serial No. PCT/US97/10063, the disclosure which is hereby incorporated by reference. That application is owned by the assignee of this present application. While the shielded connectors and latching systems disclosed in the above noted application provide improved shielding and latching characteristics, there is a desire to improve these connectors and make them more space efficient. 
     SUMMARY OF THE INVENTION 
     In order to improve the attachment of a shielded connector onto a cable, an improved means and method for providing strain relief was developed. A strain relief member is placed on the cable prior to attachment of other parts of the connector to the cable. A terminal block is secured on the conductors of the cable, the shielding sheath of the cable is associated with a ferrule of the strain relief member, and the shielding member is placed around the terminal block and in mounting relationship with the strain relief member. Parts of the shield member may be associated with the strain relief member. Thereafter a clamp is applied to clamp the shielding sheath and preferably an outer insulating cover of the cable on the strain relief ferrule. 
     A latch member is provided on a connector with which the cable connector is to be mated. The latch may engage portions of the strain relief member or other portions of the cable connector. Structure is provided for removably mounting latching members on a connector housing using simple tools or latch parts for demounting the latch. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an exploded isometric view of a shielded cable connector according to the invention; 
     FIG. 1 a  is an isometric view of the cable connector shown in FIG. 1, in assembled condition; 
     FIG. 2 is a side cross section of a preferred form of a strain relief member; 
     FIG. 3 is a fragmentary cross sectional view of a preferred form of attachment of a cable to the strain relief member shown in FIG. 2; 
     FIG. 4 illustrates a method of assembling the cable connector shown in FIG. 1; 
     FIG. 5 is a partial cross sectional view showing a cable connector latched into a mating header connector according to one embodiment of the invention; 
     FIGS. 6 a  and  6   b  show, respectively, side and frontal elevations of the latch member shown in FIG. 5; 
     FIG. 7 shows another embodiment of cable to header interconnection; 
     FIGS. 8 a  and  8   b  show respectively a side cross sectional view and a front elevational view of the latch used in the FIG. 7 embodiment. 
     FIG. 9 illustrates another embodiment of latch for latching a cable connector to a header; 
     FIG. 10 shows a cable interconnection utilizing the latch shown in FIG. 9; 
     FIG. 10 a  is a fragmentary cross-sectional view showing the latch member of FIG. 9 in operative position; 
     FIG. 11 is a front isometric view of a modification of the latch member of FIG. 9; 
     FIG. 12 is a front elevational view of the latch member shown in FIG. 11; 
     FIG. 13 is a rear elevational view of the latch member of FIG. 11; 
     FIG. 14 is a side elevational view of the latch member shown in FIG. 11; 
     FIG. 15 illustrates another embodiment of latch member wherein the latch is mounted on the cable connector instead of the header; 
     FIG. 16 is an exploded isometric view of a cable connector utilizing the latch shown in FIG. 15; 
     FIG. 17 is an isometric view of a cable interconnection using the latching arrangement illustrated in FIGS. 15 and 16. 
     FIG. 18 is an exploded isometric view of a cable connector utilizing another latch embodiment; 
     FIG. 19 is an isometric view of the cable connector of FIG. 18 in partially assembled condition, without a latch; 
     FIG. 20 is an isometric front view of a latch used with the cable connectors shown in FIGS. 15-19; 
     FIG. 21 is an exploded isometric view of another embodiment of shielded cable connector using a shrinkable tube as a clamp ring; and 
     FIG. 22 is an exploded isometric view of another embodiment of cable connector. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1 shows generally the principal components of a cable connector  10  in accordance with the invention. The connector  10  includes mating shields  11  and  11 ′ that intermate with each other and are held together by tabs  11   a  and  11   a ′, that interfit and lock with locking portions  11   b  and  11   b ′. In addition, the shields  11  and  11 ′ can include openings  11   c  and  11   c ′ that are adapted to receive the latching protrusions  17   d  disposed on opposed outer surfaces of the terminal block  17 . Each of the shields  11  and  11 ′ includes a cable engaging portion  12  and a pair of opposed openings  13  disposed along an upper edge. 
     Each connector  10  includes a strain relief member  15  that comprises a plate or wall member  18  having a central opening surrounded by a ferrule  14 . The plate  18  includes a plurality of mounting lugs  16  that are adapted to be received in the openings  13  of the shields. 
     The connector  10  also includes a terminal mounting block  17  that preferably is formed by a plurality of like modules  17   a ,  17   b  and  17   c  that are snapped or otherwise held together to form the block  17 . The modules  17   a, b, c  are is formed of a suitable dielectric material and each receives a plurality of contact terminals, for example, receptacle terminals, to which individual conductors of a cable are associated. 
     Referring to FIG. 1 a , when the shields  11 ,  11 ′ are secured about the terminal block  17 , the strain relief member  15  is held in place by the shields, by reason of the interfit of tabs  11   a ,  11   a ′ with locking portions  11   b ,  11   b ′ and lugs  16  extending through the openings  13 . In addition, the cable engaging members  12 , preferably in the form of semi-circular members, encircle the ferrule  14 . As shown in FIG. 1 a , the terminal block  17  forms a plurality of openings  17   e , for receiving terminals, such as pins, from a mating header. 
     FIG. 2 illustrates in greater detail a preferred form of strain relief member  15 . The member  15  includes a plate or wall member  18  having an opening for receiving a cable. Disposed about the generally centrally positioned opening is a ferrule  14  that includes a first section  14   a  and a reduced diameter section  14   b . The plate  18  includes lugs  16  at each corner. The lugs  16  are preferably canted upwardly. 
     FIG. 3 shows a cable  20  mounted on the strain relief member  15 . For drawing simplicity, the group of mutually insulated conductors or wires within the cable is not shown. As shown, the outer insulative layer  22  of the cable has been stripped back to reveal the conductive shielding sheath  24 , usually in the form of a wire braid. The strain relief member has been applied to the cable in a manner such that the ferrule  14  receives the braided sheath in an encircling relationship to sections  14   a  and  14   b . In addition, a portion of the insulative cover  22  is received over the reduced diameter section  14   b . Cable engaging portions  12  of the shields are disposed over the ferrule  14  and serve as a stop against insulative cover  22 . A clamping member in the form of a crimp ring  26  is disposed over the assembly of the ferrule, the cable and the shield parts  12 . When the crimp ring  26  is compressed, the clamping force exerted by the ring clamps the shielding sheath  24 , the shield parts  12 , and the outer insulative cover  22  against the ferrule  14 , which acts as an anvil. As can be seen in FIG. 3, the reduced diameter portion  14   b  is provided to allow for the presence of the portion of the insulative cover  22  that is captured beneath the crimp ring  26 . 
     FIG. 4 illustrates in sequential steps the process for attaching a connector onto a cable  20 . In a first step, the cable is prepared by stripping a portion of the outer insulative cover or sheath  22  to reveal the braided sheath  24 . Thereafter, the crimp ring  26  is slid over the stripped portion of the cable. Thereafter, the braid is cut back to an appropriate length and the strain relief member  15  is slid onto the cable, with the ferrule  14  disposed beneath the braid and preferably a portion of the outer cover  20 . Then each of the individual modules  17   a ,  17   b  and  17   c  is associated with the appropriate conductors of the cable. After the conductors are fixed to the terminals, the modules  17   a ,  17   b  and  17   c  are snapped or otherwise secured together to form a terminal block. When the modules are secured together, the two halves of the shields  11  and  11 ′ are snapped in place over the terminal block  17 . In a final step, the crimp ring  26  is slid over the ferrule  14  of the strain relief member  15  and is then subjected to a crimping operation. The crimp ring  26  exerts an inward force to clamp the conductive sheath of the cable, the outer insulative layer of the cover and the cable engaging portions of each shield part against the ferrule  14 , thereby securing the connector onto the cable. 
     Referring to FIG. 5, a cable connector  10  is shown attached to cable  20  in the manner previously described. The cable connector  10  is received in a mating header connector  30 . The header connector  30  includes an associated pin field formed of an array of pins (not shown) that mate with terminals in the terminal blocks  17 . FIG. 5 further illustrates a latch for latching the cable connector  10  to the header  30 . One side wall  32  of the header  30  includes an opening or passageway  34  for receiving the mounting legs  38  of a latch  36 , shown further in FIGS. 6 a  and  6   b . The leg  38  includes a locking latch  40  that resiliently engages with the latching surface or detent  42  formed in side wall  38  of the header. The upper end of the latch  36  includes two opposed openings  44  for receiving the canted lugs  16  of the strain relief member  15 . To provide additional locking capabilities, a latch hook  46  is carried on the side of the latch  36  adjacent the connector  10 . The latch member  46  is shaped and positioned to interact with the base  18  of the strain relief member  15 , to provide additional latching. Canting the lugs  16  as shown enhances retention of the lugs in openings  44  and overcomes the effects of tolerance build-up between the latch and cable connector. 
     The side wall  32  of header  30  also includes two rows of lateral apertures  96  and  96 a spaced vertically from each other (FIGS. 5,  7  and  17 ). The aperture  96   a  forms along its top edge the previously mentioned latching surface  42 . The apertures  96  and  96   a  are arranged along a vertical line and extend to opening  34 . The apertures  96   a  are shaped and sized form release spaces to receive the distal ends of the mounting legs  38  when inserted in the direction of arrow R (FIG.  7 ). In this manner, a spare latch member  36 ,  50  or  60  can be used to push the locking latch  40  away from latch surface  42 , to release the latch member and allow its removal from the header  30 , for example, if the latch is broken. Thus, no special tool is needed for latch removal. 
     Alternatively, latch removal may be effected from the top of header  30  by inserting an elongate tool (not shown) through slots  112  (FIGS. 5,  7  and  10 ), that are axially aligned with the distal ends of openings  34  in the top or an upper surface of side wall  32 . The tool is pushed a sufficient distance into opening  34  along a release space formed between side walls of opening  34  and legs  38  to move the locking latch  40  away from the latch surface  42  to release the latch member. 
     As is later explained, the upper row of openings  96  can receive the projection  78  of the connector mounted latch  70  illustrated in FIGS. 15-20. Thus, the header  30  with the provision of a plurality of apertures  96  and  96   a , can be simultaneously used in systems having either header mounted latching or connector mounted latching. This reduces tooling costs by providing these alternative capabilities in the same header part. 
     It should be noted that in this embodiment, the crimp ring  26  is spaced from the base plate  18  to provide clearance for the latch hook  46 . 
     The housing of the header  30  may be formed of a dielectric material or of a suitable conductive material, depending upon shielding requirements. 
     Referring to FIGS. 6 a  and  6   b , the latch member  36  includes a plurality of mounting legs  38 , each of which has a locking latch  40 , as previously described. At the opposite end, the latch  36  includes the openings  44  for receiving lugs  16  and the latching hook  46 . The latch  36  is preferably formed by molding a suitable polymeric material. 
     In operation, as the cable connector  10  is inserted into header  30 , the latching hook  46  engages the exterior shields  11  of the connector, thereby deflecting the latch generally to the left, as viewed in FIG.  5 . As the connector  10  is near its fully mated position, the latch hook passes beyond the back edge of the shield member, thereby allowing the latch to resile toward the right, and thereby allowing the lugs  16  to enter into the openings  44 , to retain connector  10  on header  30 . To remove the connector  10  from the header, the upper end of the latch is moved to the left so that the latch hook  46  is clear of the shield member and the lugs  16  are no longer positioned in the openings  44 . 
     FIG. 7 illustrates a somewhat modified form of the strain relief and latching arrangement illustrated in FIG.  5 . In this embodiment, the crimp ring  26  is made longer so that its bottom edge can engage the plate  18  whereby the base plate  18  functions as a positioning stop for the crimp ring. In this embodiment, latch  50  is secured in a side wall  32  of the header  30  in the same manner as discussed with respect to latch  36 . The abutment of the longer crimp ring against base plate  18  leaves less space for placement of the hook  46  shown in FIG.  5 . Consequently, the upper end of the latch  50  does not carry any latching hook. Rather, retention of the connector  10  on the housing  30  is effected only by the lugs  16  entering the openings  44  of the latch member (see FIGS. 8 a  and  8   b ). 
     Referring to FIG. 9, another embodiment of latch member is shown. In this embodiment, the latch member  60  includes a plurality of latch fingers  62  and a plurality of latching projections  64 . Referring to FIGS. 10,  10   a  and  11 - 14 , the latch member  60  is secured onto wall  32  of the header  30  in the same manner as previously described with respect to the latches shown in FIGS. 5 and 7. In the embodiment of FIGS. 9,  10  and  10   a , the latch fingers  62  latch behind the back edge of the shield members of the connector  10 . The embodiment of FIGS. 11-14 differs from that of FIGS. 9-10 a  by the elimination of latch fingers  62 . This arrangement allows overall size reduction of the cable connector and is used when the cable and associated strain relief structure extend to the side surfaces of the shields leaving little or no space for fingers  62 . Alternatively, centrally located latch fingers may be deleted, leaving only fingers adjacent the edges of latch members  60 . In these embodiments, the projections  64  comprise the primary means for securing the cable connection  10  to header  30 . The projections  64  enter matching openings  63  in the adjacent surface of the shield  11  for additionally securing the cable connector  10  into the header  30 . Thus, in this version, there are no openings for receiving lugs from the strain relief member as in previous embodiments. This arrangement provides for improved fixing of the connector  10  in the header  30  under the influence of the force of the cable acting on the connector. Usually, the cable exerts a lateral force in either direction of arrow F (FIG.  10 ), tending to rotate or pull the cable connector away from the header. In the embodiments of FIGS. 5 and 7, the openings  44  and lugs  16  must be sized and located under very close tolerances to effectively counter such rotation. However, in the FIGS. 9-14 embodiments, the generally cylindrical projections  64  do not require such high tolerance placement to resist such rotation of the connector. A factor that influences the improved retention of this embodiment is explained in FIG. 10 a . Preferably, the longitudinal axis A of each projection  64  is canted with respect to a line H, which line H is orthogonal to the direction V of the plane of the side surfaces of shield  11  in which opening  63  is formed. By canting the projections  64 , the projections reliably enter the openings  63  without the need to tightly tolerance the locations of the projections  64  and openings  63 . The canting essentially absorbs the effects of any tolerance build-ups. This is so because the canted upper and lower surfaces of the projections can engage edges of openings  63  at varying positions over a relatively wide tolerance range. 
     As shown in FIG. 12, the spacing P between projections  64  is preferably equal to the grid pitch of the connector module. Hence the latch members can straddle adjacent header modules. As shown in FIGS. 13 and 14, the outside surface of each mounting leg  38  is provided with a longitudinally extending groove  114  aligned with slots  112  formed at the distal end of the latch member  60 . The grooves  114  provide additional clearance and guidance for a removal tool (not shown), as previously mentioned, that is inserted from the top of the header  30 , into openings  34  (FIGS. 5 and 7) as a means for removing the latch member  60  from a header. 
     Also, as shown the crimp ring  26 ′ is of a hexagonal form rather than a cylindrical form of previous embodiments (FIG.  10 ). The hexagonal ferrule centers in the assembly tooling more readily and provides more space at the back edge of the shield for latches. 
     FIG. 15 illustrates a latch  70  that is mounted on the cable connector, rather than on the header. In this embodiment, the latch  70  includes a body member  72  that includes at one end a finger engaging portion  74 . At the other end there is disposed a plurality of latching fingers  76 , each of which carries a latching projection  78 . Intermediate the ends of the body  72  is a reduced thickness region  80 , that is designed to facilitate bending of the body  78  along its longitudinal axis. On a reverse side, the body  72  carries a mounting plate  82  having securing lugs  84  positioned thereon. The mounting plate  82  is secured onto body  72  through “living hinge” section  86 . The latch member  72  also includes a fulcrum member  88  carrying stepped surfaces  90 . 
     Referring to FIG. 16, a latch member  70  is secured onto a cable connector  10  by means of key ways  92  formed in one of the shields  11 . By inserting the securing lugs  84  into the key ways  92 , the latch  70  is retained on the cable connector. 
     Referring to FIG. 17, as the cable connector  10  is inserted into header  30 , the fingers  76  enter into longitudinally extending openings  34  in the top of the side wall  32 . The latch protrusions  78  enter into openings  96  in the side wall, and latch against the side walls of the openings  96 , thereby securing the cable connector onto the header. In order to separate the cable connector from the header, a force is applied to the finger engaging portion  74  of the latch. The step  90  (FIG. 11) acts as a fulcrum against the back edge  98  of the shield  11 . As a result, the latch body  72  flexes outwardly in the region of the bendable area  80 . Outward flexure of the bendable area  80  results in rotation of the bottom portion of the latch member  72  about the hinge  86 , thereby causing the fingers  76  to be moved inwardly, retracting the latch projections  78  from the openings  96 . In this condition, the cable connector  10  is free to be withdrawn from the header  30 . 
     FIG. 18 shows another embodiment of a cable connector generally along the lines of that previously described with respect to FIGS. 15 through 17. However, in this embodiment, the latch  100  is mounted on the cable connector in a different fashion. In this embodiment, as in previous embodiments, the shields  11 ,  11 ′ are placed about the terminal block  17 , that can be comprised of individual modules  17   a ,  17   b  and  17   c as previously described. The modules carry structure that extends through one of the shield halves, for example, shield  11 ′, for mounting the latch  100  onto the connector. In the illustrated embodiment, this structure comprises generally T-shaped or dovetail mounting members  104 . As illustrated in FIG. 19, the members  104  extend through openings  110  in the shield  11 ′. 
     As shown in FIG. 20, the latch member  100  includes a finger engaging portion  74 ′, a reduced thickness, bendable portion  80 ′ and latch fingers  76  carrying latching elements  78 , as previously described with reference to the FIG. 13 embodiment. The latch also includes a mounting plate  102  secured onto the latch body by a “living hinge” portion  108 , also as previously described. A laterally extending dovetail groove  106  is formed on the mounting plate  102 . The groove  106  is sized and shaped to be fitted over the dovetail shaped mounting members  104  by a transverse sliding movement of the plate  102  over the mounting members  104 . The groove  106  and mounting members  104  are configured and sized so that there is a substantial friction fit between the members  104  and the groove  106  to retain the latch  100  in place. The latch also includes, as in previous embodiments, the fulcrum member  108  with step  90 . The step  90  co-acts with the back edge of the shield  98 , as previously described with respect to the embodiment of FIG.  13 . The latch  100  and the latch  70  are preferably formed as a one piece molding of a thermo-plastic material. The latch  100  operates in essentially the same fashion as the latch  70 , to retract the latching elements  78  of the latch fingers  76  from engagement with latching surfaces in a mating header. That is, applying a force directed toward the shield to portion  74  causes outward flexure of bendable portion  80 , thereby causing the latch fingers  76  to be retracted in the direction of the shield. 
     FIG. 21 shows a modified form of cable connector that comprises a plurality of terminal block modules  117   a, b  and  c , that are joined together as in previous embodiments. In order to provide for proper assembly of the terminal modules within the shields  11  and  11 ′, the modules have keying members  126  formed on opposite side surfaces. The keying members  126  are differently shaped on opposite sides of the terminal module to allow the terminal modules to be properly oriented in the shield halves. For example, the keying members  126  on the right hand side of the terminal modules in FIG. 21 are circular and are shaped and sized to fit closely within like shaped openings  124  in shield part  11 ′. Corresponding keying members (now shown) on the opposite edge of the terminal modules are another shape, for example, a rectangular shape that matches with a rectangular opening  122  in the shield part  11 . In order to lessen EMI radiation from the connector, all of the elements that extend through openings in the shields, such as guidance members  130  and keying members  126  fit closely within associated openings  124 , such as openings  124 ,  131  and  130 , respectively, in the shield. 
     To further enhance EMI shielding, the shield parts  11 ,  11 ′ shown in FIG. 21 include side shielding members  120  that form part of the strain relief structure. The members  120  are preferably formed integrally with the shields and extend upwardly to provide additional shielding at the top end of the connector. The shielding members  120  also contribute to the mechanical strength at the interface between the cable and the connector. 
     In this embodiment, the clamping member  26 ′ comprises a shrinkable tubular element, for example, formed of a heat shrinkable polymer. In this arrangement, the strain relief member  15  is similar to that previously described and is associated with the shield parts  11  and  11 ′ in the same manner. However, in this embodiment, the clamping member  26 ′ is placed over the members  12  and  120  and then shrunk to create an inwardly directed compressive force against the strain relief member  15 , thereby clamping the shield and sheath layers of the cable against the strain relief member. 
     In the embodiment of cable connector illustrated in FIG. 22, the basic parts of this connector system are similar to that previously described in connection with FIG.  21 . This construction is especially useful with connection with the embodiments illustrated in FIGS. 9-14, wherein openings  63  are formed in one of the shield parts  11 ′. In this embodiment, the base plate  18  of the strain relief member  15  includes additional shielding structure for creating an electrical shield beneath the openings  63 , to further enhance EMI shielding properties. As shown, the additional shielding structure comprise a downwardly extending wall  19  with a lip  21  formed along an edge thereof. The lip is positioned to bear against the inner surface of shield  11 ′ below the row of holes  63 . This structure provides a relief space adjacent the opening  63  to allow entrance of the projections  64 , yet provides a shield around the openings  63 . Preferably, the base member  18 , depending shield  19  and lip  21  are formed integrally, for example, by casting. 
     It should be noted that the width of the latch member illustrated in all of the embodiments discussed above can be made to match the overall width of the cable connector  10 . Thus, if the cable connector comprises only one of the terminal block modules the width of the latch member is made to accommodate the narrower cable connector. 
     The foregoing embodiments provide many product advantages. Coaxial cables tend to be somewhat stiff, especially in larger sizes. In addition, in many applications, there is very limited space for the cable to bend. These factors place strong demands on the strain relief between the connector and the cable. By providing a separate strain relief or anvil member, that can be associated with the cable prior to crimping, improved cable retention results. 
     Further, by providing latching that engages the strain relief structure, more secure latching results. By configuring the strain relief member to receive a portion of the insulative cover of the cable, additional improvements in the strain relief are realized. In addition, space required for the latching mechanism is minimized. 
     While the present invention has been described in connection with the preferred embodiments of the various figures, it is to be understood that other similar embodiments may be used or modifications and additions may be made to the described embodiment for performing the same function of the present invention without deviating therefrom. Therefore, the present invention should not be limited to any single embodiment, but rather construed in breadth and scope in accordance with the recitation of the appended claims.