Abstract:
A connector for a data communications system has a housing containing a printed circuit board. The printed circuit board has insulation displacement contacts for connecting with wires in a cable. The insulation displacement contacts are connected to nose contacts which are also mounted on the printed circuit board. The nose contacts form a channel between the nose contacts and the printed circuit board. A strain relief member is located in the channel. The strain relief member absorbs mating forces generated during connection and disconnection of the connector.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates to an electrical connector that meets high performance standards, particularly in high speed data transmissions. More specifically, the present invention relates to an electrical connector receivable in another mating connector that includes a housing, a strain relief member, a printed circuit board, nose contacts, and insulation displacement contacts that reduces near end crosstalk, thereby increasing performance to meet high performance standards, such as in category 6 applications.  
       BACKGROUND OF THE INVENTION  
       [0002]     Due to advancements in telecommunications and data transmission speeds over unshielded twisted wire pair cables, the connectors (such as jacks and plugs) have become critical impediments to high performance data transmission at high frequencies. Some performance characteristics, particularly near end crosstalk, degrade at higher frequencies in environments such as the Category 5e and Category 6 environments specified in the TIA/EIA-568-B series of commercial building cabling standards.  
         [0003]     When electrical signals are carried on a signal line or wire which is in close proximity to another signal line or other signal lines, energy from one signal can be coupled into adjacent signal lines by the electrical field generated by the potential between the two signal lines and the magnetic field generated as a result of the changing electrical fields. This coupling, whether capacitive or inductive, is called crosstalk when the coupling occurs between two or more signal lines. Crosstalk is a noise signal and degrades the signal-to-noise (S/N) margin of a system. In communication systems, reduced S/N margin results in greater error rates in the information conveyed on the signal lines. Crosstalk generated at the connection between cables and connectors has become a significant problem.  
         [0004]     Another significant problem with connectors is mechanical breakage of the connectors during installation and maintenance. A common type of connection in telecommunications and data networking is a connection between a cable and a  110  connection block. This connection comprises of a cable with a connector with female contacts and a connection block with male contacts. The connector is installed by pressing it onto the connection block. Friction forces between the pairs of mating contacts hold the connector in place.  
         [0005]     This press-fit installation of the connectors to the connection block generates mating forces in the contacts in the connector. The mating forces can be substantial and can result in unacceptable loosening or breakage of joints (such as solder joints) in the connector. Removal of the connector generates similar forces in an opposite direction, and can result in the same unacceptable loosening or breakage. During the expected lifetime of a connector, it may be installed and removed numerous times, further compounding the potential damage caused by mating forces.  
         [0006]     Damage can also be caused by improper usage of connectors. When removing a cable connector from a connection block, the user should grasp the housing of the connector and apply the removal force directly to the housing. In practice, however, connectors are often removed by pulling on the cable rather than the housing. This generates axial forces along the cable and causes strain in the connections between the cable and connector. This strain can result in undesirable breakage of the connection between the cable and the connector.  
       SUMMARY OF THE INVENTION  
       [0007]     An object of the present invention is to provide an electrical connector or cable for a communications systems which will reduce or not induce crosstalk in the system.  
         [0008]     Another object of the present invention is to provide an electrical connector or a cable which will reduce potential breakage due to mating forces generated during connection or disconnection.  
         [0009]     A further object of the present invention is to provide an electrical connector or cable which will reduce potential breakage due to axial loading forces on the cable.  
         [0010]     Yet another object of the present invention is to provide an electrical connector which is simple and inexpensive to manufacture and use.  
         [0011]     These objects are basically obtained by an electrical connector comprising a housing and a printed circuit board. The printed circuit board is contained within the housing. A plurality of insulation displacement contacts are mounted on the printed circuit board for connection to a cable. A plurality of nose contacts are also mounted on the printed circuit board. The nose contacts are configured to form a channel between the nose contacts and the printed circuit board, and a strain relief device is mounted within the channel. The strain relief device accepts mating forces and alleviates the strain on solder connections during connection and disconnection.  
         [0012]     Other objects, advantages, and salient features of the present invention will become apparent from the following detailed description, which, taken in conjunction with the annexed drawings, discloses preferred embodiments of the invention. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]     Referring to the drawings which form a part of this disclosure:  
         [0014]      FIG. 1  is a perspective view of an electrical connector according to the present invention;  
         [0015]      FIG. 2  is a perspective view of the printed circuit board of  FIG. 1  without the strain relief member for clarity;  
         [0016]      FIG. 3  is a side elevational view in cross-section taken along line A-A of  FIG. 2 ;  
         [0017]      FIG. 4  is a perspective view of the printed circuit board of  FIG. 1  with the strain relief member;  
         [0018]      FIG. 5  is a side elevational view in cross-section taken along line B-B of  FIG. 4 ;  
         [0019]      FIG. 6  is a bottom view of the printed circuit board of  FIG. 1 ;  
         [0020]      FIG. 7  is a perspective view of a nose contact according to a second embodiment of the present invention;  
         [0021]      FIG. 8  is a top view of the connector of  FIG. 1  assembled with a cable;  
         [0022]      FIG. 9  is a perspective view of a variation of the electrical connector of  FIG. 1 ; and  
         [0023]      FIG. 10  is a perspective view of a variation of the electrical connector of  FIG. 1 . 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0024]     Referring initially to  FIG. 1 , an electrical connector  20  according to the present invention comprises a housing  22  having a cable connection end  24  and a contact end  26  at the opposite longitudinal ends of the housing. A printed circuit board  28  is contained within the housing  22 . A plurality of insulation displacement contacts  30  and nose contacts  32  are mounted on the printed circuit board and are electrically connected by circuit traces on the printed circuit board  28 . A strain relief member  60  is mounted in a channel  58  defined by the nose contacts and circuit board.  
         [0025]     Housing  22  comprises a housing top  34  and a housing bottom  36 . In the illustrated embodiment, the housing top  34  and housing bottom  36  are connected by a living hinge  38 . The living hinge allows the housing top and bottom to move from an open position illustrated in  FIG. 1  to a closed position (not illustrated). The halves may be held closed by mechanical engagement, sonic welding, or any other method known to those in the art. On the cable connection end  24 , the housing top  34  has a recess  40  and the housing bottom  36  has a corresponding recess  42 . When the housing is closed, the recesses  40 ,  42  form a cable pathway  44  to allow a cable to enter the housing. The configuration of housing  22 , including the position of the nose contacts  32  at the contact end  26 , conforms to standard connector geometry and pin out definitions for communications systems. Housing  22  is particularly suitable for use with 110 termination blocks used in the wiring industry.  
         [0026]     The recesses  40 ,  42  provide strain relief for a cable passing through the cable pathway  44  by absorbing axial loading forces applied to a cable located within the recess. This strain relief may be accomplished by sizing the recesses  40 ,  42  to provide a friction fit between the recesses and a cable jacket. Alternatively, as illustrated in  FIG. 9 , the strain relief may be accomplished by applying an adhesive  82  to the recesses  40 ,  42  to form an adhesive connection between the recesses and a cable jacket, or as illustrated in  FIG. 10 , by providing piercing members  84  in the recesses to pierce a cable jacket. In this manner, when axial forces are applied to the cable, the forces are transferred to the housing  22  rather than to the connection between the insulation displacement contacts  30  and the individual wires connected thereto.  
         [0027]     Adjacent the contact end  26 , the housing  22  contains printed circuit board  28 . As known to those skilled in the art, the insulation displacement contacts  30  are typically contained within a separate plastic housing, which is not shown here for the sake of clarity. The printed circuit board  28  may be fastened to the housing permanently or may be detachable. A detachable board allows replacing the printed circuit board to upgrade the connector to meet different performance requirements.  
         [0028]     Referring now to  FIG. 3 , each nose contact  32  is generally U-shaped, with a solder tail  46 , a connector portion  48 , and a contact portion  50 . Each solder tail  46  extends through an opening  51  in the printed circuit board  28  and is soldered to the printed circuit board by solder  52 . The contact portions  50  extend past the edge  54  of the printed circuit board  28  so that the contact portions may interface with a connection block, which is not illustrated here. Each of the nose contacts  32  forms an opening  56  located between each nose contact and the printed circuit board. Together, these openings  56  form a channel  58  that is sized to receive a strain relief member  60 . For clarity, the strain relief member is illustrated in  FIGS. 4-5 , but is not illustrated in  FIGS. 2-3 .  
         [0029]      FIGS. 4-5  show the printed circuit board  28  with the strain relief member  60  in place. The strain relief member  60  is a generally rectilinear bar and is formed from any suitable dielectric material, such as plastic. The strain relief member abuts the nose contacts  32  or the nose contacts may be partially embedded in the strain relief member. The strain relief member may be fastened to the printed circuit board  28 , fastened to the housing  22 , or may float free. When the electrical connector  20  is pushed onto a connecting block, the mating forces produced on the nose contacts  32  are transferred to the strain relief member  60 . This alleviates strain on the solder connections between the solder tails  46  of the nose contacts  32  and the printed circuit board  28 .  
         [0030]     Referring now to  FIG. 6 , the solder tails  46  of the nose contacts  32  and the solder tails  62  of the insulation displacement contacts  30  extend through the printed circuit board  28  and are soldered to the printed circuit board. Each nose contact  32  is connected to a corresponding insulation displacement contact by a circuit trace  64 . The circuit traces  64  are configured on the printed circuit board  28  in a pattern that minimizes and/or reduces return loss and near end crosstalk noise. The pattern of the circuit traces (e.g. length, separation, thickness, and width) can be determined by software simulation, trial and error, or a combination of the two methods. U.S. Pat. No. 6,057,743, which is hereby incorporated by reference in its entirety, discloses an example of a noise reduction circuit formed on a printed circuit board.  
         [0031]     A nose contact  66  according to a second embodiment of the present invention is illustrated in  FIG. 7 . The nose contact comprises a contact portion  68 , a connector portion  70 , and a solder tail  72 , which are located in the same general plane. A tab  74  extends from joint between the contact and connector portions and extends perpendicular to the plane formed by the contact portion  68 , connector portion  70 , and solder tail  72 . When placed in the housing  22 , the tab  74  abuts the strain relief member  60  and assists in the transmission of forces from the nose contact  66  to the strain relief member  60 .  
         [0032]      FIG. 8  shows the connector of the present invention fastened to an unshielded twisted wire pair cable  74 . The cable  74  has four twisted wire pairs  76  that extend along a generally longitudinal axis  78 . The twisted wire pairs  76  are surrounded by a flexible insulation sheath  80 . The cable  74  passes through the cable pathway  44  in the housing  22 . Each wire within the cable  74  is connected to a corresponding insulation displacement contact  30  in a conventional manner.  
         [0033]     While various embodiments have been chosen to illustrate the invention, it will be understood by those skilled in the art that various changes and modifications can be made therein without departing from the scope of the invention as defined in the appended claims.