Abstract:
A plug for a universal serial bus connector in the USB 3.0 standard to which a cable is connected to form a connector assembly, the cable including a signal line for the USB 2.0 standard and a ground line and being fixed by a cable fixing section of a connector shell, the plug includes an electrode which approximately abuts a distal end of the cable fixing section in the connector assembly, and to which at least one of the signal line for the USB 2.0 standard and the ground line is connected.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation application based on a PCT Patent Application No. PCT/JP2009/006477, filed Nov. 30, 2009, whose priority is claimed on Japanese Patent Application No. 2008-321099 filed Dec. 17, 2008, the entire content of which are hereby incorporated by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to plug for a universal serial bus (hereinafter abbreviated as “USB”) connector (hereinafter abbreviated as “plug”), and a connector assembly using the plug, and in particular relates to the structure of a Standard-A plug or a Standard-B plug in the USB 3.0 standard. 
     2. Description of the Related Art 
     A USB connector is a type of connector that is used for the connection of electronic devices including personal computers and peripheral devices, and is widely used due to having the advantages of easy connection to a device, plug-and-play or hot plugging capability, and capability of being used as a terminal for power supply (refer to Japanese Unexamined Patent Application, First Publication No. 2001-217026, Published Japanese Translation No. 2008-508694 of the PCT International Publication, Japanese Utility Model (Registered) Publication No. 3059768, and http://www.hirose.co.jp/catalogj_hp/j24000019). The specification of the plug that constitutes a USB connector and the receptacle into which the plug is inserted are defined by standards. 
     On the other hand, in connecting a plug and cable to form a USB connector assembly, the structure of the connection portion is not particularly specified. For example, as shown in  FIG. 7 , a structure is employed in which a plug  1  is housed in a metal connector shell  2 , a jacket  3   a  of a cable  3  is fixed in a grasping manner in a clamp portion  2   a  that is provided at the base end portion of the connector shell  2 , and a plurality of electrical wires  3   b  that extend from the distal end of the jacket  3   a  to the distal end side are connected to a plurality of electrodes  1   a  arranged at the base end portion of the plug  1 . Also, in the case of the cable  3  used for the USB 3.0 standard, the aforementioned plurality of wires  3   b  consist of two pairs of signal lines for the USB 3.0 standard that are shielded, one pair of wires for the USB 2.0 standard that are not shielded, a power line and a ground line, for a total of eight wires (only five are shown in the figure). Note that in the following disclosure, unless otherwise noted, the left side in the figures (the side to be inserted into a receptacle) shall be defined as the distal end side, and the right side (the side connected to the cable) as the base end side. 
     In the aforementioned cable  3 , the plurality of wires  3   b  are covered from the outer side by a jacket  3   a  and a braid  3   c . Accordingly, during the connection described above, work called “leading” is required to remove the jacket  3   a  and the braid  3   c  to enable connection of the wires  3   b  to the electrode  1   a  of the plug  1 . In the aforementioned conventional connector assembly, the distance between the location where the jacket  3   a  and the braid  3   c  of the cable  3 , that is fixed to the clamp portion  2   a , are removed by leading, and each electrode  1   a  of the USB plug  1  (the distance shown by the letter D in  FIG. 7 ) is substantially equivalent. Accordingly, the lengths of the plurality of (exposed) wires  3   b  that extend from the distal end of the jacket  3   a  and the braid  3   c  to the distal end side by leading are substantially equivalent. 
     However, when the lengths of the plurality of wires  3   b  in the aforementioned exposed portion are equivalent, in the signal wires for the USB 2.0 standard in which the periphery is not particularly shielded, since the surrounding shield by the braid  3   c  is eliminated, they become more susceptible to external noise. In addition, since the braid  3   c  is eliminated, there is also the problem of the region in which impedance mismatching between the paired signal wires for the USB 2.0 standard occurs expanding. Note that  FIG. 7  shows the example of a Standard-A plug in the USB 3.0 standard, but even in the Standard-B plug in the USB 3.0 standard, a similar problem occurs. 
     The present invention was achieved in view of the aforementioned circumstances, and the object thereof is to provide a plug for a universal serial bus connector and a connector assembly that, in a plug for a USB connector and a connector assembly using the plug, can reduce the effects of external noise that the signal wires for the USB 2.0 standard receive and impedance mismatching between the paired signal wires for the USB 2.0 standard. 
     SUMMARY 
     The first aspect of the present invention is a plug for a universal serial bus connector in the USB 3.0 standard to which a cable is connected to form a connector assembly, the cable including a signal line for the USB 2.0 standard and a ground line and being fixed by a cable fixing section of a connector shell, the plug including an electrode which approximately abuts a distal end of the cable fixing section in the connector assembly, and to which at least one of the signal line for the USB 2.0 standard and the ground line is connected. 
     The second aspect of the present invention is a connector assembly including: the plug for a universal serial bus connector according to claim  1 ; and the cable that includes the signal line for the USB 2.0 standard, a signal line for the USB 3.0 standard, a power line, and the ground line, wherein the length from a distal end of a jacket of the cable to a distal end of the signal line for the USB 2.0 standard is shorter than the length from the distal end of the jacket to a distal end of the signal line for the USB 3.0 standard. 
     It may be arranged such that the lengths to the distal end of the signal line for the USB 2.0 standard, the power line, and the ground line with respect to the distal end of the jacket of the cable differ from each other. 
     The plug for a universal serial bus connector may be a Standard-A plug in the USB 3.0 standard. 
     The plug for a universal serial bus connector may be a Standard-B plug in the USB 3.0 standard. 
     According to the present invention, since the signal lines for the USB 2.0 standard that are not shielded can be connected to the electrodes at positions closer to the base end side compared to a conventional plug, it is possible to shorten the overall length of the signal lines for the USB 2.0 standard, which are susceptible to external noise. As a result, the range of being susceptible to external noise of the signal lines for the USB 2.0 standard shortens, and the effect of external noise on the signal lines decreases. Also, since the region where impedance mismatching between the paired signal lines for the USB 2.0 standard occurs (non-shielded region) narrows, the aforementioned impedance mismatching decreases. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is perspective view that shows an upper side of an example of the structure of the plug for the USB connector according to the first embodiment of the present invention. 
         FIG. 2  is perspective view that shows a lower side of an example of the structure of the plug for the USB connector according to the first embodiment of the present invention. 
         FIG. 3  is a partial cross-sectional view that shows an example of the structure of the connector assembly according to the first embodiment of the present invention. 
         FIG. 4  is perspective view that shows an upper side of an example of the structure of the plug for the USB connector according to the second embodiment of the present invention. 
         FIG. 5  is perspective view that shows a lower side of an example of the structure of the plug for the USB connector according to the second embodiment of the present invention. 
         FIG. 6  is a partial cross-sectional view that shows an example of the structure of the connector assembly according to the second embodiment of the present invention. 
         FIG. 7  is perspective view that shows an upper side of an example of the structure of a conventional connector assembly. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     [Embodiment 1] 
     Hereinafter, embodiments of the present invention shall be described with reference to the drawings. 
       FIG. 1  and  FIG. 2  show schematic configurations of a plug  11  for a USB connector according to the first embodiment (Embodiment 1) of the present invention.  FIG. 1  is an upper side perspective view that shows the obverse side of the plug  11 , and  FIG. 2  is a lower side perspective view that shows the reverse side of the plug  11 . This plug  11  corresponds to the aforementioned conventional plug  1 , and in terms of standards, corresponds to the Standard-A plug in the USB 3.0 standard. 
     The plug  11  is constituted by a main body  12  that is made of resin, and electrodes  13   a  to  13   d  that are arranged in the main body. The main body  12  is provided with a center portion  12   a  that is supported by a connector shell (refer to reference numeral  2  in  FIG. 3  described below) during forming of the connector assembly, a distal end portion  12   b  that extends from the center portion  12   a  to the distal end side and that is inserted into a receptacle (not shown), and a base end portion  12   c  that extends from the center portion  12   a  to the base end side and that is used for connection with a cable described below. Also, the shapes of the center portion  12   a  and the distal end portion  12   b  as well as the arrangement of the electrodes  13   a  to  13   d  in the main body  12  conform to the USB 3.0 standard. 
     In this plug  11 , the constitution of the base end portion  12   c  differs from that of the conventional plug  1 . That is, in the plug  11 , the base end portion  12   c  extends to a position closer to the base end side compared to the aforementioned conventional plug  1 . Specifically, the base end portion  12   c  extends with the same width and same thickness as the conventional plug  1  to a position that approximately abuts the distal end of the clamp portion of the connector shell (refer to reference numeral  2   a  of  FIG. 3  described below) during formation of the connector assembly. Here, the “position that approximately abuts the distal end of the clamp portion” means a position at which a base end edge  12   d  of the base end portion  12   c  abuts the distal end face of the clamp portion, or faces it with a slight clearance. 
     Moreover, the electrodes  13   d  that are positioned on the reverse surface of the base end portion  12   c  (for electrical wire connections in accordance with the USB 2.0 standard) extend to the base end edge  12   d , along the extension direction of the base end portion  12   c , in the state of four being arranged at a predetermined interval in the width direction, in contrast to the conventional plug  1 . Note that the arrangement of the electrodes  13   a  that are positioned on the obverse base end portion of the distal end portion  12   b  (for receptacle connection in accordance with the USB 3.0 standard) and the electrodes  13   b  positioned on the obverse distal end portion of the distal end portion  12   b  (for receptacle connection in accordance with the USB 2.0 standard), and the electrodes  13   c  positioned on the obverse surface of the base end portion  12   c  (for electrical wire connections in accordance with the USB 3.0 standard) are the same as for the conventional plug  1 . 
     Then, for example as shown in  FIG. 3 , the plug  11  is housed in the metal connector shell  2 , and the jacket  30   a  of the cable  30  that has been led is fixed in a grasping manner in the clamp portion  2   a  (cable fixing section) that is provided at the base end portion of the connector shell  2 . Moreover, the electrodes  13   c  and  13   d  of the plug  11  and the plurality of wires that extend from the distal end of the jacket  30   a  to the distal end side (refer to reference numerals  30   b  to  30   e  described below) are connected. In this way, a connector assembly  40  is formed. 
     In this case, in the plug  11  of the present embodiment, as stated above, the base end portion  12   c  of the main body  12  extends to a position that approximately abuts the distal end of the clamp portion  2   a  of the connector shell  2  during formation of the connector assembly  40 . Also, the electrodes  13   d  that are positioned on the reverse surface of the base end portion  12   c  extend to the base end edge  12   d  along the extension direction of the base end portion  12   c.    
     Accordingly, when forming the connector assembly  40 , it becomes possible for the paired signal lines  30   c  for the USB 2.0 standard that are not shielded, the power line  30   d , and the ground line  30   e  to be connected to the electrodes  13   d  at different positions from one another with respect to the extension direction of the base end portion  12   c . As a result, the length of the two paired signal lines  30   b  for the USB 3.0 standard to be connected to the electrodes  13   c  positioned at the distal end side of the base end portion  12   c , the length of the electrical wires to be connected to the electrodes  13   d  (the signal lines  30   c , the power line  30   d  and the ground line  30   e ), as well as the lengths among the electrical wires to be connected to the electrodes  13   d  (the signal lines  30   c , the power line  30   d  and the ground line  30   e ) can be made to differ with respect to one another. 
     In particular, since the pair of signal lines  30   c  that are not shielded can be connected to the electrodes  13   d  at positions closer to the base end side compared to the conventional plug  1 , it is possible to shorten the overall length of the signal lines  30   c , which are susceptible to external noise. As a result, the range of being susceptible to external noise of the signal lines  30   c  shortens, and the effect of external noise on the signal lines  30   c  decreases. Also, since the region where impedance mismatching between the paired signal lines  30   c  occurs narrows, the aforementioned impedance mismatching decreases. As a result, reflection of signals between the paired signal lines  30   c , signal attenuation arising from that, and crosstalk decrease. 
     [Embodiment 2] 
       FIG. 4  and  FIG. 5  show schematic configurations of a plug  51  for a USB connector according to the second embodiment (Embodiment 2) of the present invention.  FIG. 4  is an upper side perspective view that shows the obverse side of the plug  51 , and  FIG. 5  is a lower side perspective view that shows the reverse side of the plug  51 . This plug  51  in terms of standards corresponds to the Standard-B plug in the USB 3.0 standard. 
     The plug  51  is constituted by a main body  52  that is made of resin, and electrodes  53   a  to  53   d  that are arranged in the main body, similarly to the plug  11  of the aforementioned first embodiment. The main body  52  is provided with a center portion  52   a  that is supported by a connector shell during forming of the connector assembly, a distal end portion  52   b  that extends from the center portion  52   a  to the distal end side and that is inserted into a receptacle (not shown), and a base end portion  52   c  that extends from the center portion  52   a  to the base end side and that is used for connection with a cable. Additionally, the base end portion  52   c  is constituted from a thick base portion  52   d  that is positioned on the distal end side, and a thin end portion  52   e  that extends from the base portion  52   d  to the base end side. The shapes of the center portion  52   a , the distal end portion  52   b , and the base portion  52   d  of the base end portion  52   c  as well as the arrangement of the electrodes  53   a  to  53   d  in the main body  52  conform to the USB 3.0 standard. 
     In this plug  51 , the configuration of the end portion  52   e  of the base end portion  52   c  differs from that of the conventional Standard-B plug in the USB 3.0 standard (hereinbelow abbreviated as “conventional plug”). That is, in this plug  51 , the end portion  52   e  extends to a position closer to the base end side compared to the conventional plug. Specifically, the end portion  52   e  extends with the same width and same thickness as the end portion of the aforementioned conventional plug to a position that approximately abuts the distal end of the clamp portion of the connector shell (refer to reference numeral  2   a  of  FIG. 6  described below) during formation of the connector assembly. Note that the “position that approximately abuts the distal end of the clamp portion” is defined in the same manner as in the plug  11  of the first embodiment described above. 
     The electrodes shown by the reference numerals  53   c  and  53   d  (for electrical wire connections in accordance with the USB 2.0 standard) extend to the base end edge  52   f , along the extension direction of the end portion  52   e , in the state of two each being arranged at a predetermined interval in the width direction on both the obverse and reverse surfaces of the end portion  52   e  of the base end portion  52   c , in contrast to the conventional plug  1 . Note that the arrangement of the electrodes  53   a  that are positioned on the obverse surface of the distal end portion  52   b  (for receptacle connection in accordance with the USB 3.0 standard) and the electrodes positioned on the end surface of the distal end portion  52   b  (for receptacle connection in accordance with the USB 2.0 standard, not illustrated), as well as the electrodes  53   b  positioned on the obverse surface of the base portion  52   d  of the base end portion  52   c  (for electrical wire connections in accordance with the USB 3.0 standard) are the same as for the conventional plug. 
     Then, for example as shown in  FIG. 6 , the plug  51  is housed in the metal connector shell  21 , and the jacket  30   a  of the cable  30  that has been led is fixed in a grasping manner in the clamp portion  21   a  (cable fixing means) that is provided at the base end portion of the connector shell  21 . Moreover, the electrodes  53   b  to  53   d  of the plug  51  and the plurality of wires that extend from the distal end of the jacket  30   a  to the distal end side (refer to reference numerals  30   b  to  30   e  described below) are connected. In this way, a connector assembly  60  is formed. 
     In this case, in the plug  51  of the present embodiment, as stated above, among the base end portion  52   c  of the main body  52 , the end portion  52   e  that is positioned at the base end side extends to a position that approximately abuts the distal end of the clamp portion  21   a  of the connector shell  21  during formation of the connector assembly  60 . Also, the electrodes  53   c  and  53   d  that are positioned on the obverse and reverse surfaces of the end portion  52   e  extend to the base end edge  52   f  along the extension direction of the end portion  52   e.    
     Accordingly, when forming the connector assembly  60 , it becomes possible for the paired signal lines  30   c  for the USB 2.0 standard that are not shielded, the power line  30   d , and the ground line  30   e  to be connected to the electrodes  53   c  and  53   d  at different positions from one another with respect to the extension direction of the end portion  52   e . As a result, the length of the two paired signal lines  30   b  for the USB 3.0 standard to be connected to the electrodes  53   b  positioned at the base portion  52   d  of the base end portion  52   c , the length of the electrical wires to be connected to the electrodes  53   c  and  53   d  (the signal lines  30   c , the power line  30   d  and the ground line  30   e ), as well as the lengths among the electrical wires to be connected to the electrodes  53   c  and  53   d  (the signal lines  30   c , the power line  30   d  and the ground line  30   e ) can be made to differ with respect to one another. 
     In particular, since the pair of signal lines  30   c  that are not shielded can be connected to the electrodes  53   c ,  53   d  at positions closer to the base end side compared to the conventional plug, it is possible to shorten the overall length of the signal lines  30   c , which are susceptible to external noise. As a result, the range of being susceptible to external noise of the signal lines  30   c  shortens, and the effect of external noise on the signal lines  30   c  decreases. Also, since the region where impedance mismatching between the paired signal lines  30   c  occurs (non-shielded region) narrows, the aforementioned impedance mismatching decreases. As a result, reflection of signals between the paired signal lines  30   c , signal attenuation arising from that, and crosstalk decrease. 
     Note that the technical scope of the present invention is not limited to the foregoing embodiments, and various modifications can be made within a range that does not depart from the scope of the present invention. 
     For example, in the plugs  11  and  51  of the foregoing embodiments, the electrodes  13   d ,  53   c ,  53   d  for electrical connections in accordance with the USB 2.0 standard all extend to the base end edge  12   d ,  52   f  of the base end portion  12   c ,  52   c . However, if the object is to shorten the total length of the pair of signal lines  30   c  for the USB 2.0 standard that are not shielded, among the electrodes  13   d ,  53   c ,  53   d , at least only the electrodes to which the paired signal lines  30   c  for the USB 2.0 standard are connected may be extend to the base end edge  12   d ,  52   f  of the base end portion  12   c ,  52   c.