Abstract:
A cable connector comprises a circuit board and a cable. The circuit board comprises a plurality of parallel and separated first and second conductive paths with a ground area alternatively arranged between on either surface. The cable comprises a plurality of transmission channels electrically connecting to the first and second conductive paths. The intervals of the transmission channels of the cable are respectively equal to the intervals of the conductive paths, thus providing better matching impedance and efficiency.

Description:
REARGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a cable connector, more particularly, it relates to a cable connector with high transmission efficiency. 
   2. Description of the Related Art 
   As technology improves, the storage products such as hard disks and Universal Serial Bus (USB) flash memory storage devices must provide smaller profile and larger capacity. The interface transmission rate must be correspondingly enhanced as the capacity of the storage devices is increased. Impedance matching and electromagnetic interference problems, however, are getting worse and need to be solved when the interface transmission rate has been raised. Generally, the Serial ATA (SATA) transmission interface has the highest bandwidth among other computer interior transmission interface. Two conductive lines forming a transmission channel and transmitting differential Non-Return to Zero (NRZ) encoding signals are utilized in the Serial ATA. Furthermore, the lengths of the conductive line in each transmission channel must be equal, or the synchronous output signals cannot be received simultaneously, thus causing data errors. 
     FIG. 1  is a schematic view of a connecting end of a conventional cable connector  1 . In  FIG. 1 , the cable connector  1  includes two line units  11  with a plurality of wires  12  and a housing  13  with conductive terminals  14  therein. During manufacturing, the wires  12  must be manually spread and sequentially soldered on the conductive terminals  11 . The lengths of the wires are different and require accurate design to eliminate data errors caused by impedance mismatching and signal asynchronous. Furthermore, while the size and specification of the cable connector  1  are changed, it requires to design again, thus increasing cost and manufacturing yield thereof. 
   SUMMARY OF THE INVENTION 
   According to one aspect of the present invention, the present invention provides a cable connector, which is capable of high transmission rate and can be manufactured more effectively. 
   Another aspect of the present invention is to provide a cable connector, which has high competitiveness and high reliability. 
   In order to achieve the aforementioned objects, the cable connector comprises a circuit board having a plurality of parallel first signal paths and second signal paths symmetrically positioned on both sides thereof and a cable having a plurality of parallel transmission channels. The gaps between the transmission channels are corresponding to the gaps between the first signal paths and the gaps between second signal paths. Each transmission channel is electrically coupled to the first signal paths and second signal paths, respectively. 
   Each transmission channel comprises a pair of independent signal lines with a conductive layer covered thereon respectively coupled to one of the first and second signal paths to transfer differential NRZ signals. The circuit board of the embodiment comprises a grounding area with a plurality of grounding paths extended to the portions between each two signal paths. The cable connector further comprises a ground shielding unit covered outside the transmission channels and electrically coupled to the grounding area of the circuit board. 
   The cable connector comprises a plurality of conductive terminal pairs and grounding terminals. The conductive terminal pairs are electrically coupled to the first signal paths and second signal paths. Each grounding terminal comprises a second clipping portion clamping the printed circuit board and electrically coupled to the grounding area of the circuit board. 
   The cable connector further comprises a terminal positioning portion with a plurality of first terminal holes and second terminal holes, and the conductive terminal pairs are respectively inserted into the first and second terminal holes and electrically coupled to the first signal paths and second signal paths. The terminal positioning portion has a plurality of third terminal holes disposed at both sides of the first terminal holes and second terminal holes, and the grounding terminals are inserted into the third terminal holes and electrically coupled to the grounding area. 
   In a preferred embodiment, the gaps between the first signal paths are equal. The gaps between the second signal paths are equal. the vertical offset errors corresponding to the first signal paths and second signal paths are less than 20% 

   
     BRIEF DESCRIPTION OF THE DRAWING PORTIONS 
       FIG. 1  shows a schematic view of a connecting end of a conventional cable connector. 
       FIG. 2  shows a partial exploded view of the cable connector according to one embodiment of the present invention. 
       FIG. 3  shows a perspective view of the cable connector being connected with a cable according to one embodiment of the present invention. 
       FIG. 4  shows a sectional view of the cable being connected with a cable connector according to one embodiment of the present invention. 
       FIG. 5  shows a sectional view of the cable connector being assembled according to one embodiment of the present invention. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Referring to  FIGS. 2˜3 , which show a partial exploded view of the cable connector and a perspective view of the cable connector being connected with a cable according to one embodiment of the present invention. The cable connector of the present invention comprises: a circuit board  2  with symmetrical traces layout on both sides, a cable  3 , a plurality of conductive terminal pairs  5  and grounding terminals  6 , and a terminal positioning portion  4 . The cable connector as shown is connected to a matching connector  7  to transmit signals. 
   The circuit board  2  comprises a plurality of separated conductive copper traces including a plurality of parallel first signal paths  21  and a plurality of parallel second signal paths  22  symmetrically formed on another side of the circuit board  2  (please refer to  FIG. 4 , which shows an embodiment with two layers). The circuit board  2  further comprises a grounding area  23  with a plurality of grounding paths extended to the portions between each two signal paths and formed separately at both sides of each signal path. The vertical offset errors corresponding to the first signal paths  21  and second signal paths  22  are less than 20% so as to maintain better matching impedance. The cable  3  has a plurality of parallel transmission channels  31 . Each transmission channel  31  is formed by vertically symmetrical signal lines  32 ,  33 . Each signal line  32 ,  33  comprises a conductive core  35  with an insulating medium  34  and a conductive layer sequentially covered outside. The signal lines  32 ,  33  of each transmission channels  31  are individually connected to the first signal paths  21  and second signal paths  22  of the circuit board  2 . The cable connector further comprises a ground shielding unit  36  at the end of the cable, enclosing outside the transmission channels  31 . The ground shielding unit  36  further comprises a first clipping portion  37  symmetrically disposed at both sides of the transmission channels  31 , coupling and positioning to the grounding area  23  of the circuit board  2 . Thus, the transmission channels  31  can be coupled to the first signal paths  21  and second signal paths  22  firmly. 
   The terminal positioning portion  4  has an inserting end portion  41  corresponding to the matching connector  7 . The inserting end portion  41  further comprises accepting grooves  42  disposed with the same intervals to accept the conductive terminals  5  and grounding terminals  6 , which can be electrically coupled to the terminals  71  of the matching connector  7  when the cable connectors are inserted therein. The terminal positioning portion  4  comprises a plurality of first terminal holes  43  and second terminal holes  44  another side of the accepting grooves  42 . The conductive terminals  5  are electrically coupled to the first signal paths  21  and second signal paths of the circuit board  2  through the first terminal holes  43  and second terminal holes  44 . The terminal positioning portion  4  further comprises a plurality of third terminal holes  45  disposed at both sides of the first terminal holes  43  and second terminal holes  44 , and the grounding terminals  6  further comprise a second clipping portion  61 . The grounding terminals  6  can be fixed on the circuit board  2  by the second clipping portion  61  and electrically coupled to the grounding area thereof after passing through the third terminal holes  45 . Furthermore, the circuit board  2  comprises a wedge portion  24 , and the terminal positioning portion  4  comprises a buckling groove  46  corresponding to the wedge portion  24 . Thus, each conductive terminal  5  and grounding terminal  6  could be positioned to the first signal paths  21 , second signal paths  22  and grounding area  23  on the circuit board  2  through the terminal positioning portion  4 , sequentially. 
   Referring to  FIG. 5 , which shows a sectional view of the cable connector being assembled according to one embodiment of the present invention. In  FIG. 5 , each conductive core  35  of the transmission channel  31  formed by vertically symmetrical signal line  32 , 33  is straight connected to the first signal paths  21  and second signal paths  22  of the circuit board  2  while assembling. The ground shielding unit  36  of cable  3  is then positioned and connected to the grounding area  23  on the circuit board  2  by the first clipping portion  37 . Next, the conductive terminals  5  are straight connected to the first signal paths  21  and the second signal paths  22  on another side of the circuit board  2 . The grounding terminals  6  are also positioned and connected to the grounding area  23  on the circuit board  2  by the second clipping portion  61  thereof. Thus, the cable  3  and the matching connector  7  are formed straight pitch to pitch conducting so as to get better matching impedance and best transmission efficiency. 
   Therefore, the present invention relates to a cable connector with better matching impedance and high transmission efficiency so as to overcome the drawbacks of the prior art electrical connector. 
   Although a particular embodiment of the invention has been described in detail for purposes of illustration, various modifications and enhancements may be made without departing from the spirit and scope of the invention. Accordingly, the invention is not to be limited except as by the appended claims.