Abstract:
A cable connector assembly and method for making, wherein the assembly connects to a flat ribbon cable having a plurality of conductors and electrical insulation about the conductors. The cable connector assembly includes a plurality of electrical contacts, each including a terminal configured to connect to at least one of the conductors of the flat ribbon cable directly through the electrical insulation to form an electrical junction. Each contact is configured to electrically connect to an external member. The cable connector assembly has a housing for holding the contacts arranged in a first row and as second row where the contacts in the rows form a grid and are connected in an offset manner to minimize cross talk.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a multiconductor electrical cable connector and, more particularly, to IDC (insulation displacement crimp) connector assemblies for a flat ribbon-like multiconductor electrical cable. 
     Since individual manual connection of each conductor in a multiconductor electrical cable, which usually has more than three conductors and as many as eighty or more conductors therein, would be a difficult and tedious task. Therefore, a number of specialized connectors have been developed for simultaneously connecting each of the plural conductors to those of another multiconductor electrical cable via another connector, for example, to a plural signal input terminal of a computer or the like, to conductive paths on a printed circuit board or the like, etc. Typically, these specialized connectors include multiple housing parts between which the cable is clamped, and usually before or during that clamping the multiple contacts of the connector puncture the electrical insulation of the cable to connect with respective conductors therein. The housing parts are mechanically secured in clamping engagement with the cable, and strain relief is usually provided by the clamping strength and/or by the terminal parts of the contacts pierced through the cable insulation. 
     From the U.S. Pat. No. 4,824,394 an IDC connector with rotated conductor pairs and strain relief base molded onto cable is known. The IDC connector is formed by a cable termination assembly that comprises a generally flat electrical insulation. The cable has got a longitudinal extent and a planar extent. At least one pair of said conductors include connecting portions rotated relative to each other about an axis generally parallel to the longitudinal extent of the cable and aligned with respect to one another in a direction generally perpendicular to the planar extent of the cable. The conductors of said pair include an area of rotation where said conductors are so rotated. At least two electrical contacts each include terminal means for connecting with the connecting portion of a respective one of said pair of conductors and connecting means for connecting with an external electrically conductive member and a strain relief body is molded directly to said cable including the area of rotation of said pair of conductors. 
     The U.S. Pat. No. 4,030,799 shows a multiconductor electrical cable termination. The multiconductor electrical cable termination is formed as an integral structural combination of the multiconductor electrical cable, the plurality of electrical contacts, and a housing part that is molded about at least a portion of each of the contacts and a portion of the cable. Each contact forms a junction with a respective conductor of the cable, and the integral housing part is molded under elevated temperature and pressure conditions so that each of the junctions is substantially fully encapsulated by at least one of the cable insulation and the molded body part and, thus, maintained relatively free of moisture and oxygen. The terminal portion of each electrical contact preferably extends fully through the cable insulation, and openings provided in the molded housing part offer access to the ends of those terminal portions for test probing thereof. Furthermore, the terminal portion of each electrical contact is in the same plane and is offset with respect to the contacting portion thereof. The electrical contacts are arranged in a forward row and a rearward row. In the forward row they have their terminal portions offset to the left with respect to their contacting portions, and in the rearward row they have their terminal portions offset to the right with respect to the contacting portions. This offset configuration of the electrical contacts allows them to be of reasonable size and strength while the contacting portion of each electrical contact in one row is directly aligned with the contacting portion of an opposite electrical contact in the other row and with each of the relatively closely positioned parallel conductors being connected to only a single respective electrical contact. 
     In computer systems there is an increasing need for cables and connectors providing a high bandwidth and a high count of signal lines. Flat ribbon cables provide a high count of signal lines having a suitable high frequency behavior. Therefore, more and more flat ribbon cables are employed in such high frequency environments, e.g., as a connection for system-level interfacing between a computer and devices including hard disks, floppy disks, CD-ROM, printers and scanners, such as the high density 50 pin SCSI (Small Computer System Interface) 2 cable/connector. In order to improve the high frequency behavior of the cable, shieldings are provided to protect the electrical signals being transmitted through the cable from electromagnetic interference. 
     The noise caused in a cable can further be reduced by only using every other conductor in a flat ribbon cable to transmit a signal. The remaining conductors are functioning as ground lines in order to further shield the signal lines from each other. Hence, two adjacent conductors never carry signal lines, instead, signal lines and ground lines alternate, e.g., ground-signal-ground-signal and so on. However, reaching the connector most of the effort spend to improve the high frequency behavior is lost, since the cross talk of the available connectors are too high for a use in a high frequency environment. 
     SUMMARY OF THE INVENTION 
     Starting from this, the object of the present invention is to provide a cable connector assembly having an improved high frequency behavior, i.e., a cable connector assembly having a low noise characteristic. 
     According to the present invention a cable connector assembly for being connected to a flat ribbon cable containing a plurality of conductors is provided. The cable connector assembly comprises a plurality of electrical contacts arranged in a first row and a second row, whereby the arrangement of the electrical contacts forms an orthogonal grid. Assuming said plurality of conductors being consecutively numbered 1 to N, said electrical contacts being arranged in a way that an electrical contact associated to an odd numbered conductor has got adjacent electrical contacts in the same row and an electrical contact at the same position in the other row that each are associated to even numbered conductors. 
     In other words, the electrical contacts are being arranged in a way that the electrical contact associated to one conductor is spaced further apart to the electrical contact associated to the respective next but one neighboring conductor, so that cross talk is reduced when having every other conductor assigned to a signal line and the remaining conductors to ground lines. 
     Hence, according to the present invention a cable connector assembly for being connected to a flat ribbon cable including a plurality of conductors and electrical insulation about said conductors maintaining the latter electrically insulated from each other. The cable connector assembly comprises a plurality of electrical contacts, each including terminal means being configured to connect at least one of said conductors directly through said electrical insulation to form an electrical junction, and contacting means on each of said electrical contacts being configured to electrically connect each of said electrical contacts to an external member. It further comprises a housing for holding said contacting means arranged in a first row and a second row forming an orthogonal grid. Assuming the plurality of conductors being consecutively numbered 1 to N, said electrical contacts being formed so that such terminal means being associated with odd-numbered conductors being respectively connected with every other contacting means of said first row and every other contacting means of the second row, being offset by one, whereby such arrangement causes each conductor being space further apart to its next but one neighboring conductor so that cross talk is reduced when having every other conductor assigned to a signal line and the remaining conductors to ground lines. 
     The advantage is that a good high frequency behavior is provided by just providing in average one ground line per signal line and having maximum separation of signal lines from each other in the connector itself. 
     Furthermore, the present invention allows to use flat ribbon cables in areas in which up to know only more expensive cables could be used, such as coax cable, but the invention may not be a substitute for coax cables in general. The costs may be significantly reduced for a respective connection. 
     Advantageously, a connector in accordance with the present invention still meets the form requirements set by the International Electromechanical Commission (IEC), i.e., it is still form fit compatible, while providing a significantly improved crosstalk behavior between adjacent signal lines. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     These and other objects will be apparent to one skilled in the art from the following detailed description of the invention taken in conjunction with the accompanying drawings in which: 
     FIG. 1 shows a bottom view on the pin face of a low noise IDC terminal arrangement in accordance with the present invention; 
     FIG. 2 shows a perspective view of a set of electrical contacts connected to conductors of a flat ribbon cable in an arrangement according to a first embodiment of the present invention; 
     FIG. 3 shows a perspective view of the set of electrical contacts as shown in FIG. 2 without showing the flat ribbon cable; and 
     FIG. 4 shows a perspective view of a set of electrical contacts connected to conductors of a flat ribbon cable according to a second embodiment of the present invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Now with reference to FIG. 1, there is depicted a bottom view on the pin face of a low noise IDC (insulation displacement crimp) terminal arrangement  100  in accordance with the present invention. The terminal arrangement  100  is connected to a flat ribbon cable (not shown) containing a plurality of conductors (not shown) and comprises a plurality of electrical contacts numbered 1 to 20. A housing  101  is provided for holding the electrical contacts arranged in a first row as indicated by arrow  102  and a second row as indicated by arrow  104 , whereby the arrangement of the electrical contacts are forming an orthogonal grid. 
     Assuming that the plurality of conductors are consecutively numbered 1 to N, the electrical contacts 1 to 20 being arranged in a way that each of the electrical contacts 1 to 20 are configured to establish an electrical connection the particular conductor having the same number associated. That is, in the drawing of FIG. 1, the first conductor of the flat ribbon cable connects to the left most electrical contact in the first row (arrow  102 ) also marked by number 1. Whereas the second conductor of the flat ribbon cable connects to the left most electrical contact in the second row (arrow  104 ) also marked by number 2. Now, in order to arrange the electrical contacts in a way that each conductor is spaced further apart to its next but one neighboring conductor so that cross talk is reduced when having every other conductor assigned to a signal line and the remaining conductors to ground lines, the third conductor of the flat ribbon cable connects to the second electrical contact from the left in the second row (arrow  104 ) also marked by number 3. Whereas the fourth conductor of the flat ribbon cable connects to the second electrical contact from the left in the first row (arrow  102 ) also marked by number 4 and so on. Thus, the increasing numbers of the respective conductors are meandering from left to right alternating between the first and the second row. 
     With reference now to FIG. 2, there is depicted a perspective view of a set of electrical contacts  201  to  216  in an arrangement according to a first embodiment of the present invention. The electrical contacts  201  to  216  are part of a multiconductor electrical cable connector. The cable connector include a multiple conductor electrical cable  220 , a plurality of electrical contacts  201  to  216  for connection at terminal portions  221  to  236  to the respective conductors  241  to  256  of the cable, and a housing (not shown), whereby the terminal portions  221  to  236  belong to the electrical contacts  201  to  216  and are electrically connected to the conductors  241  to  256 , respectively. 
     The terminal portions  221  to  236  of each electrical contact  201  to  216  preferably include a pair of elongate prong-like arms  260  commonly supported from a base portion  262  and defining a relatively narrow slot there between. The ends of the arms  260  remote from the base portion  262  preferably are tapered or chamfered to define an entranceway into the narrow slot and to form generally pointed tips to pierce easily through the cable insulation  264 . The width of the narrow slot is preferably narrower than the normal diameter of one of the conductors  241  to  256 . Therefore, as a typical electrical contact  201  is joined with the cable  220  by urging the two toward each other, the pointed tips pierce through the insulation  264  while the wide chamfered entranceway guides the conductor  241  into the narrow slot. As the conductor  241  enters the slot, it is somewhat flattened squeezed to provide a relatively enlarged surface area of a gas tight engagement or connection with the two arms  260 . 
     The terminal portions  260  of each the electrical contacts  201 ,  205 ,  209  and  213  are in the same plane. The same applies to the terminal portions of electrical contacts  202 ,  206 ,  210  and  214 , as well as to electrical contacts  203 ,  207 ,  211  and  215  as well as to electrical contacts  204 ,  208 ,  212  and  216 . Preferably, the conductors  242 ,  244 ,  246 ,  248 ,  250 ,  252 ,  254  and  256  being connected to electrical contacts  202 ,  204 ,  206 ,  208 ,  210 ,  212 ,  214  and  216 , respectively, are tight to ground. Hence, the arrangement of the terminal portions of such electrical contacts form a shielding separating the terminal portions of electrical contacts  201 ,  205 ,  209  and  213  from the terminal portions of electrical contacts  203 ,  207 ,  211  and  215 , which reduces the cross talk and allows to use the cable connector for higher frequencies. 
     From the illustration of FIG. 2 it can be seen that the electrical contacts  201  to  216  are arranged in a way that an electrical contact associated to an odd numbered conductor  241  to  256  has got adjacent electrical contacts in the same row and an electrical contact at the same position in the other row that each are associated to even numbered conductors. For example, electrical contact  203  is associated to odd numbered conductor  243 . It has got adjacent electrical contacts  202  and  206  in the same row and an electrical contact  204  at the same position in the other row that each are associated to even numbered conductors. In other words, the electrical contact  203  associated to conductor  243  is arranged to be spaced further apart to the electrical contact  201  (or  205 ) associated to the respective next but one neighboring conductor  241  (or  245 ). Therefore, cross talk is reduced in the cable connector according to the present invention, when every other conductor is assigned to a signal line and the remaining conductors to ground lines. 
     To abstract, the electrical contacts are arranged in a first row (arrow  271 ) and a second row (arrow  272 ). Furthermore, they are formed so that such terminal portions  260  being associated with odd-numbered conductors  241 ,  243 ,  245 , . . . ,  255  being respectively connected with every other electrical contact of said first row (cf.  201 ,  205 ,  209  and  213 ) and every other contacting means of the second row (cf.  203 ,  207 ,  211  and  215 ), being offset by one. 
     Moreover, while the invention is illustrated and described above with reference to multiconductor electrical cable connector located at an end of the multiconductor electrical conductor, it will be apparent that such a connector also may be provided in accordance with the invention at a location on a multiconductor electrical cable intermediate the ends thereof. 
     Now with reference to FIG. 3, there is shown a perspective view of the set of electrical contacts  301  to  316  as shown in FIG. 2 without depicting the flat ribbon cable, whereby the electrical contacts  301  to  316  of FIG. 3 correspond to the electrical contacts  201  to  216  of FIG.  2 . 
     Each electrical contact  301  to  316  is provided with a terminal portions  320 . The terminal portion  320  of each electrical contact  301  to  316  preferably include a pair of elongate prong-like arms  322 ,  324  commonly supported from a base portion  326  and defining a relatively narrow slot  328  there between. The ends of the arms  322 ,  324  remote from the base portion  326  preferably are tapered or chamfered to define an entranceway into the narrow slot  328  and to form generally pointed tips  330 ,  332  to pierce easily through a cable insulation. 
     The electrical contacts  301  to  316  are arranged in a first row (arrow  341 ) and a second row (arrow  342 ). As it can be seen in particularly in FIG. 3, the electrical contacts  301 ,  305 ,  309  and  313  in the first row (arrow  341 ) have their terminal portions offset away from the second row (arrow  342 ) with respect to their contacting portions, i.e., the portion aligned in the two rows. Whereas the electrical contacts  304 ,  308 ,  312  and  316  in the first row (arrow  341 ) have their terminal portions offset towards the second row (arrow  342 ) with respect to their contacting portions. Correspondingly, the electrical contacts  303 ,  307 ,  311  and  315  in the second row (arrow  342 ) have their terminal portions offset away from the first row (arrow  341 ) with respect to their contacting portions, whereas the electrical contacts  302 ,  306 ,  310  and  314  in the second row (arrow  342 ) have their terminal portions offset towards the first row (arrow  341 ) with respect to their contacting portions. 
     Each of the contact terminal arms  322 ,  324  is preferably sufficiently long to extend fully through the cable (cf. FIG. 2) with a portion, for example, including the pointed ends  330 ,  332 , being exposed beyond the plane of the cable (cf. FIG.  2 ). 
     Finally, with reference to FIG. 4, there is depicted a perspective view of a set of electrical contacts connected to conductors of a flat ribbon cable according to a second embodiment of the present invention. The electrical contacts  401  to  416  are part of a multiconductor electrical cable connector. As in the previous embodiment, the electrical contacts  401  to  416  are arranged in a first row (arrow  471 ) and a second row (arrow  472 ). The cable connector include a multiple conductor electrical cable  420 , a plurality of electrical contacts  401  to  416  for connection at terminal portions  421  to  436  to the respective conductors  441  to  456  of the cable, and a housing (not shown), whereby the terminal portions  421  to  436  belong to the electrical contacts  401  to  416  and are electrically connected to the conductors  441  to  456 , respectively. 
     The terminal portions  421  to  436  of each electrical contact  401  to  416  preferably include a pair of elongate prong-like arms as known from the first embodiment described above. 
     The terminal portions  421  to  436  of each the electrical contacts  401 ,  405 ,  409  and  413  are in the same plane approaching the flat ribbon cable  420  from the top. The same applies to the terminal portions of electrical contacts  404 ,  408 ,  412  and  416 . In contrary, the electrical contacts  402 ,  406 ,  410  and  414  as well as the electrical contacts  403 ,  407 ,  411  and  415  approach the flat ribbon cable from below, whereby each set of electrical contacts are again arranged that the respective terminal portions are placed in the same plane. Thus, the electrical contacts shown in FIG. 4 differ only in such a way from the electrical contacts according to the first embodiment that the depicted arrangement is suitable for a connector having the electrical contacts pointing in the same direction as the conductors of the flat ribbon cable. 
     However, from the illustration of FIG. 4 it can be seen that the electrical contacts  401  to  416  itself are arranged in a the same way as explained for the first embodiment with regard to FIGS. 2 and 3. Thus, electrical contact  403  associated to odd numbered conductor  443  has got adjacent electrical contacts  402  and  406  in the same row and an electrical contact  404  at the same position in the other row that each are associated to even numbered conductors. In other words, the electrical contact  403  associated to conductor  443  is arranged to be spaced further apart to the electrical contact  401  (or  405 ) associated to the respective next but one neighboring conductor  441  (or  445 ). Therefore, cross talk is reduced in the cable connector according to the present invention, when every other conductor is assigned to a signal line and the remaining conductors to ground lines. 
     While the preferred embodiment of the invention has been illustrated and described herein, it is to be understood that the invention is not limited to the precise construction herein disclosed, and the right is reserved to all changes and modifications coming within the scope of the invention as defined in the appended claims.