Abstract:
The connector of the present invention is terminated to an end of a cable, and comprises the following components, which are arranged coaxially: support mandrel, a swaging barrel surrounding the support mandrel, and a swaging cap outside the swaging barrel. The swaging cap has a variable internal diameter which decreases toward the end facing the cable to form a hump-like inner protrusion, and when moved axially, swages the swaging barrel to secure the outer jacket of the electrical cable.

Description:
[0001]    This Application claims priority to provisional application No. 60/430,343 filed on Dec. 3, 2003. 
     
    
     
       FIELD OF INVENTION  
         [0002]    The present invention is directed to a connector of the type conventionally known as a BNC connector. Such connectors are known for use in several areas, including, the connection of video and radio-frequency (RF) cables. More particularly, the present invention is directed to a single-piece, RFI-tight, compression BNC connector which has optimized RF performance. The connector according to the present invention can be used in cable television head-end applications and elsewhere in the broadcast industry, e.g., control room and studio environments. Of course, its utility is not limited to the broadcast industry.  
         BACKGROUND OF THE INVENTION  
         [0003]    BNC connectors are used in a wide range of instruments and for a variety of purposes, ranging from connecting probes on equipment to general input and output of signals. Their popularity stems from their easy availability and relatively low cost. The basic BNC connector is a male type connector mounted at an end of an RF cable. The connector has a center pin connected to the center cable conductor and a metal tube connected to the outer cable shield. A rotating ring outside the tube locks the cable to a corresponding female connector.  
           [0004]    One method of terminating the connector is to insert an electrical cable into a rear barrel, and using a tool, crimp the barrel around the electrical cable&#39;s jacket to secure it thereto. However, that method requires the use of a tool (please confirm) that encircles the barrel and crimps it down onto the cable jacket. That process is unwieldy and inconvenient, and often yields an inconsistent crimping force resulting in a crimp that is too loose or too tight.  
           [0005]    Therefore, it would be advantageous to provide a BNC connector that simplifies the termination of the BNC connector, and yields a consistent crimping force. Furthermore, because BNC connectors are produced in large numbers, relatively minor manufacturing cost savings can have a significant impact on the profitability of the connectors. Therefore, it would be advantageous to provide a BNC connector which is terminated more quickly and efficiently, to reduce the manufacturing cost of assembling the connector to an electrical cable.  
         SUMMARY AND OBJECTS OF THE INVENTION  
         [0006]    The present invention is directed to a connector, preferably a BNC type, for terminating the end of a cable. A rear end of the connector, which is connected to the cable, comprises the following components, which are arranged coaxially: support mandrel, a swaging barrel surrounding the support mandrel, and a swaging cap outside the swaging barrel. The support mandrel has holding spurs or barbs. The swaging barrel is made of a material which can be swaged under sufficient pressure. The swaging cap has a variable internal diameter which decreases toward the end facing the cable to form a hump-like inner protrusion.  
           [0007]    The cable is inserted such that the outer conductor is disposed between the support mandrel and the swaging barrel. Then, the swaging cap is pushed with an appropriate tool so that its inner protrusion swages the swaging barrel against the cable outer conductor. Thus, the cable outer conductor is compressed against the holding barbs of the support mandrel.  
           [0008]    The connector of the present invention further comprises a center contact which forms the pin of the BNC connector. The center contact is hollow so as to receive the inner conductor of the cable. The center contact has inwardly extending tangs which contact the inner conductor.  
           [0009]    The connector still further comprises an outer connecting barrel which provides an RFI-tight connection with improved stress resistance. The slots are lengthened, and a dimple functioning as a secondary stress relief area is provided.  
           [0010]    Modifications of the connector are possible. For example, the swaging barrel can be solid or slotted. Other features of the present invention will be understood from the specification sheet and the drawings. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]    [0011]FIG. 1 shows a connector of the present invention in an open position;  
         [0012]    [0012]FIG. 2 shows the connector of the present invention in the open position coupled to an electrical cable;  
         [0013]    [0013]FIG. 3 shows the connector of the present invention coupled to an electrical cable in a closed position;  
         [0014]    [0014]FIG. 4 shows an electrical cable;  
         [0015]    [0015]FIG. 5 shows the electrical cable prior to coupling with the connector of the present invention;  
         [0016]    [0016]FIG. 6 shows two alternative embodiments of a swaging barrel;  
         [0017]    [0017]FIG. 7 shows a contact for the front portion of the connector of the present invention;  
         [0018]    [0018]FIG. 8 shows a sectional view of line  8 - 8  of FIG. 7;  
         [0019]    [0019]FIG. 9A shows a finger of a front barrel of the connector;  
         [0020]    [0020]FIG. 9B shows a prior art front barrel finger;  
         [0021]    [0021]FIG. 10A shows the finger of the front barrel mated to a corresponding barrel; and  
         [0022]    [0022]FIG. 10B shows a prior art front barrel finger mated to a corresponding barrel.  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0023]    Referring now to the several drawing figures in which identical elements are numbered identically throughout, a description of the preferred embodiment of the present invention will be provided.  
         [0024]    [0024]FIG. 1 shows the BNC connector  2  of the present invention in an open position prior to attachment to an electrical cable  10 . FIGS. 2 and 3 show the steps for attaching the BNC connector  2  to the electrical cable  10 .  
         [0025]    Referring to FIG. 1, a rear portion of the BNC connector  2  is terminated onto an electrical cable  10 , and includes a support mandrel  4 , a swaging cap  6  and a swaging barrel  8 . The support mandrel  4  includes a plurality of spurs  12  that engage a cable jacket, as explained below. A front portion of the BNC connector  2  includes a contact  14 , into which the conductor of the electrical cable  10  is inserted. The contact  14  is surrounded by a front barrel  40  that mates with the corresponding female receptacle (not shown). The front barrel  40  includes six resilient spring fingers  42  that engage a corresponding barrel in the female receptacle.  
         [0026]    [0026]FIGS. 4 and 5 show the electrical cable  10 . FIG. 4 shows the various layers of the electrical cable, which include, starting from the center and going outward, its center conductor  20 , an inner dielectric  22 , a inner foil  24 , a weaved shielding braid  26 , an outer foil  28 , and an outer cable jacket  30 . Prior to inserting the electrical cable  10  into the BNC connector  2 , the electrical cable  10  is partially stripped, as shown in FIG. 5. The outer foil  28  is removed and the shielding braid  26  is pulled back so that the inner dielectric  22  and the inner foil  24  are partially exposed. Furthermore, the inner dielectric  22  and the inner foil  24  are removed along a portion of the cable so that the center conductor  20  is exposed. It should be understood that the electrical cable  30  described herein is provided for exemplary purposes, and that cables having additional layers, or cables having layers removed, may be used with the present invention without departing from the spirit or scope of the invention.  
         [0027]    The electrical cable  10  is inserted into the rear portion of the BNC connector  2 , through the support mandrel  4 , so that the conductor  20  protrudes into the front barrel  40  of the connector, and into the interior of the contact  14 . The inner dielectric  22  and inner foil  24  are inserted into the support mandrel  4  and abut a retainer wall  32  adjacent thereto. However, the edge of the support mandrel  4  slides underneath the shielding braid  26  and outer cable jacket  30 , so that they are inserted over and around the support mandrel  4 . That is best shown in FIG. 2, which illustrates the shielding braid  26  and cable jacket  30  located between the support mandrel  4  and the swaging barrel  8 , and in particular, shows a protracted portion of the shielding braid  26  curling against an interior wall of the swaging barrel  8 .  
         [0028]    After the electrical cable is inserted, the swaging cap  6  is moved along the length of the swaging barrel  8 , by hand or tool, into a closed position, shown in FIG. 3. The swaging cap  6  includes a protrusion  7  on its end, which upon being moved, deforms an arm  9  of the swaging barrel  8  into contact with the cable jacket  30 . The cable jacket  30  and shielding braid  26  are then secured between the deformed arm  9  and the spurs  12  on the support mandrel  4 . FIG. 6 shows two alternative embodiments of the swaging barrel  8 , one solid and the other slotted. Either type of swaging barrel  8  may be used depending on the application.  
         [0029]    [0029]FIGS. 7 and 8 show the front contact  14  in greater detail. The contact  14  has a hollowed interior with at least two spring tangs  15  inclined inwardly into the hollowed interior. The tangs  15  resiliently engage the conductor  20  upon insertion of the electrical cable  30 , and provide a continuous electrical connection between the conductor  20  and the contact  14 .  
         [0030]    [0030]FIGS. 9A and 10A show a further improvement of the present invention directed towards the fingers  42  of the front barrel  40 . It should be noted that in FIG. 1, the fingers  42  extend to the left, so that a corresponding female receptacle is inserted from the left to the right. In FIGS. 9A and 10A, the finger  42  extends to the right, and the female receptacle is inserted from the right to the left. Furthermore, the finger  42  shown in FIG. 9A and 10A is formed from a top portion of the barrel  40 , so that a hollowed out portion or dimple  44  faces outwardly. Upon mating the front barrel  40  with a barrel  46  of a corresponding female receptacle, the fingers  42  of the front barrel  40  are deflected inwardly to provide a frictional engagement between the two barrels. The dimple  44  provides a stress relief region that reduces the stress in the finger  42  by making it easier for the finger  42  to deflect. Additionally, the slot length of the finger  42  is lengthened so that it is better able to bend. The increased slot length and dimple  44  make it easy for the finger  42  to adjust to the inclined plane of the barrel  46  of the female receptacle so that they contact each other over a larger surface area. The increased contact area provides better shielding for the connector.  
         [0031]    That construction is in contrast to the prior art fingers  50  shown in FIGS. 9B and 10B. The prior art fingers  50  do not have a dimple  44  and typically include a protuberance  52  on an end thereof. When mated with a barrel of a corresponding female receptacle, as shown in FIG. 10B, the protuberance  52  abuts the finger  46  of the female receptacle so that only its tip contacts the finger  46 . Furthermore, because the finger  50  does not include a dimple, the finger  50  does not have a suitable position that deflects with the finger  46 . That creates stress in the finger  50 .  
         [0032]    It should be appreciated that many other modifications and variations of the present invention are possible in light of the above teachings, without departing from the spirit or scope of the invention. For example, the preferred materials described above may be modified or changed so long as they individually, and in combination, perform their intended function.