Patent Publication Number: US-7223121-B2

Title: Cable connector for balanced transmission

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention generally relates to a cable connector for balanced transmission in which a number of pairs of wires are used. 
   2. Description of the Related Art 
   As data transmission systems, there are systems such as a normal transmission system that uses a wire for each data signal, and a balanced transmission system that uses a pair of wires for each data signal and transmits a + signal and a − signal, whose size is the same as that of the + signal with the opposite direction from the + signal, at the same time. The balanced transmission system has an advantage of being relatively immune to noise compared with the normal transmission system. Therefore, the balanced transmission system has been widely used. In order to establish a transmission line that executes balanced transmission of data between apparatuses, a cable connector for balanced transmission is used. The cable connector for balanced transmission is shielded at the end of the cable for balanced transmission. 
     FIG. 1  is an exploded perspective view of a conventional cable connector for balanced transmission  10 .  FIG. 2  is a cross-sectional view of the conventional cable connector for balanced transmission  10  shown in  FIG. 1 . In drawings, a line X 1 –X 2  shows the width direction, a line Y 1 –Y 2  shows the length direction, and a line Z 1 –Z 2  shows the height direction. 
     FIG. 3  is a cross-sectional view of a cable for balanced transmission  20  shown in  FIG. 1 . As shown in  FIG. 3 , the cable for balanced transmission  20  has a structure in which a number of pairs of wires  21  are disposed in a tube of a double-cover tube composed of an outer cover  27  and a shielding mesh wire  28 , where each of the wires  21  has a pair of first and second covered signal wires  22 - 1  and  22 - 2  for balanced signal transmission and a drain wire  25  banded by a spirally-wrapped metal tape. As shown in  FIG. 6 , from the end of the pair of wires  21 , the first and second covered signal wires  22 - 1  and  22 - 2  and the drain wire  25  are extended, and the covers at the tips of the first and second covered signal wires  22 - 1  and  22 - 2  are removed and first and second signal wires  23 - 1  and  23 - 2 , respectively, (tips of the first and second covered signal wires  22 - 1  and  22 - 2 ) are naked and exposed. The first signal wire  23 - 1  pairs up with the second signal wire  23 - 2 . 
   As shown in  FIGS. 1 and 2 , in the cable connector for balanced transmission  10 , a relay board  12  is provided at the Y 1  side of a contact assembly body  11 , and the first and second signal wires  23 - 1  and  23 - 2  and the drain wire  25  further extending from the pairs of wires  21  extended from the end of the cable for balanced transmission  20  are soldered to terminals of the Y 1  side of-the relay board  12 . In addition, shielding covers  31  and  32  cover the contact assembly body  11 , the relay board  12 , and the end part of the cable for balanced transmission  20 . In the cable connector for balanced transmission  10 , the contact assembly body  11 , the relay board  12 , and the ends of the cable for balanced transmission  20  form data transmission paths (refer to Patent Document 1). 
   [Patent Document 1] Japanese Laid-Open Patent Application No. 2003-059593 
   In the cable connector for balanced transmission  10 , when the shield between the adjacent two data transmission paths is studied, there is a problem in the part of the relay board  12 . That is, the relay board  12  has a structure in which wiring patterns extending in the Y 1 –Y 2  direction are formed on the upper face and the lower face of the relay board  12  in a manner so that the wiring patterns are arrayed in the X 1 –X 2  direction, and the wiring pattern on the upper face pairs up with the wiring pattern on the lower face at the same position. Consequently, it is difficult to provide excellent shielding at the place between adjacent wiring patterns in the X 1 –X 2  direction comparable to the shielding degree at the contact assembly body  11 . 
   Recently, the signal speeds in clients and servers have become high; therefore, a bad influence on transmission characteristics caused by poor shielding at the relay board  12  cannot be ignored. 
   In addition, a cable connector for balanced transmission is required for which low cost manufacturing and highly efficient assembly can be achieved. 
   SUMMARY OF THE INVENTION 
   Accordingly, the present invention may provide a cable connector for balanced transmission in which transmission characteristics of high speed signals are improved. 
   According to a preferred embodiment of the present invention, there is provided a cable connector for balanced transmission. The cable connector for balanced transmission includes a contact assembly body having a block body made of an electrically insulating material in which a pair including first and second signal contact members and a ground contact member are alternately arrayed. A first signal wire connecting part being a part of the first signal contact member sticks out from the back face of the block body, a second signal wire connecting part being a part of the second signal contact member sticks out from the back face of the block body, and a plate part and a drain wire connecting part at the end of the plate part being parts of the ground contact member stick out from the back face of the block body. The cable connector for balanced transmission further includes a cable for balanced transmission having plural pairs of wires in which the first and second signal wires and the drain wire are disposed. A tip of the first signal wire is connected to the first signal wire connecting part, a tip of the second signal wire is connected to the second signal wire connecting part, and a tip of the drain wire is connected to the drain wire connecting part. The cable connector for balanced transmission further includes a spacer member being a plate-shaped member made of an electrically insulating material that has first grooves having a shape corresponding to the first signal wire connecting part, second grooves having a shape corresponding to the second signal wire connecting part, and slits having a shape corresponding to the plate part of the ground contact member. The spacer member is attached to the back face of the block body, and the first signal wire connecting part is inserted into the first groove, the second signal wire connecting part is inserted into the second groove, and the plate part is inserted into the slit; with these connections, the positions of the first and second signal contact members and the ground contact members in relation to the tips of the cable for balanced transmission are decided. 
   According to embodiments of the present invention, the positions of the first and second signal wire connecting parts and the drain wire connecting part can be easily decided by the spacer member. 
   In addition, according to the embodiments of the present invention, the first and second signal wires of the cable for balanced transmission are respectively connected to the first and second signal wire connecting parts whose positions are decided, and the drain wire of the cable for balanced transmission is connected to the drain wire connecting part whose position is decided. Therefore, connecting wires can be executed in a stable manner without deforming the first and second signal wire connecting parts and the drain wire connecting part. Consequently, the manufacturing efficiency becomes high. 
   In addition, the first and second signal wires are directly connected to the first and second signal contact members, respectively, without being connected via a relay board. Therefore, the crosstalk characteristic of the cable connector for balanced transmission of an embodiment of the present invention is improved. 
   In addition, the ground contact members sandwich the first and second signal contact members therebetween and shield them. Consequently, the shielding effect for the first and second signal wires is improved. 
   Other objects and further features of the present invention will be apparent from the following detailed description when read in conjunction with the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is an exploded perspective view of a conventional cable connector for balanced transmission; 
       FIG. 2  is a cross-sectional view of the conventional cable connector for balanced transmission shown in  FIG. 1 ; 
       FIG. 3  is a cross-sectional view of a cable for balanced transmission shown in  FIG. 1 ; 
       FIG. 4  is an exploded perspective view of a cable connector for balanced transmission according to a first embodiment of the present invention; 
       FIG. 5A  is a perspective view showing tips of a cable for balanced transmission that are connected to a contact assembly body in the cable connector for balanced transmission; 
       FIG. 5B  is a diagram showing details of the connection shown in  FIG. 5A ; 
       FIG. 6  is an exploded perspective view in which the tips of the cable for balanced transmission and the contact assembly body are shown; 
       FIG. 7  is a cross-sectional view of the cable connector for balanced transmission at a position of first and second signal contact members; 
       FIG. 8  is a cross-sectional view of the cable connector for balanced transmission at a position of a ground contact member; 
       FIG. 9  is a cross-sectional view of the cable connector for balanced transmission at a position of a locking arm member; 
       FIG. 10  is a transverse sectional-view of the cable connector for balanced transmission at a position of the contact assembly body; 
       FIG. 11  is a diagram showing a first signal contact member; 
       FIG. 12  is a diagram showing a second signal contact member; 
       FIG. 13  is a diagram showing a ground contact member; 
       FIG. 14  is a perspective view showing the contact assembly body and the spacer member; 
       FIG. 15  is a perspective view showing a block body and the spacer member; 
       FIG. 16  is a perspective view showing a tip part of the cable connector for balanced transmission; 
       FIG. 17  is a perspective view showing the cable connector for balanced transmission to which a hood and an outer cover are attached; 
       FIG. 18  is a diagram showing the locking arm member; 
       FIG. 19  is a perspective view of a cable connector for balanced transmission according to a second embodiment of the present invention; 
       FIG. 20  is a perspective view of a cable connector for balanced transmission according to a third embodiment of the present invention; 
       FIG. 21  is a cross-sectional view of a part of the cable connector for balanced transmission shown in  FIG. 20 ; 
       FIG. 22  is an exploded perspective view of a cable connector for balanced transmission according to a fourth embodiment of the present invention; 
       FIG. 23  is a perspective view of the cable connector for balanced transmission shown in  FIG. 22 ; 
       FIG. 24  is a perspective view of the cable connector for balanced transmission shown in  FIG. 23  where a shielding cover assembly body is removed; 
       FIG. 25  is a perspective view of an inner cap shown in  FIG. 22 ; 
       FIG. 26  is an exploded perspective view of the inner cap and the shielding cover assembly body; 
       FIG. 27  is a perspective view showing the inner cap and a first shielding cover; 
       FIG. 28  is a schematic diagram where gaps between the X 1  and X 2  sides of the inner cap and the shielding cover assembly body are closed; 
       FIG. 29  is a perspective view of a cable connector main body in which a relay board is used; 
       FIG. 30  is a diagram showing a part of a cable connector for balanced transmission according to a fifth embodiment of the present invention; 
       FIG. 31  is a perspective view of a connector for a printed circuit board according to a sixth embodiment of the present invention; 
       FIG. 32  is a perspective view of the Y 2  side of a connector main body with a metal gasket according to the sixth embodiment of the present invention; and 
       FIG. 33  is a diagram showing the connector for the printed circuit board that is mounted on a printed circuit board according to the sixth embodiment of the present invention. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Referring to the drawings, embodiments of the present invention are explained. 
   First Embodiment 
     FIG. 4  is an exploded perspective view of a cable connector for balanced transmission  50  according to a first embodiment of the present invention.  FIG. 5A  is a perspective view showing tips of a cable for balanced transmission  20  that are connected to a contact assembly body  51  in the cable connector for balanced transmission  50 .  FIG. 5B  is a diagram showing details of the connection shown in  FIG. 5A .  FIG. 6  is an exploded perspective view in which the tips of the cable for balanced transmission  20  and the contact assembly body  51  are shown.  FIG. 7  is a cross-sectional view of the cable connector for balanced transmission  50  at a position of first and second signal contact members  53  and  54 .  FIG. 8  is a cross-sectional view of the cable connector for balanced transmission  50  at a position of a ground contact member  55 .  FIG. 9  is a cross-sectional view of the cable connector for balanced transmission  50  at a position of a locking arm member  56 .  FIG. 10  is a transverse sectional-view of the cable connector for balanced transmission  50  at a position of the contact assembly body  51 . In the drawings, a line X 1 -X 2  shows the width direction, a line Y 1 -Y 2  shows the length direction, and a line Z 1 -Z 2  shows the height direction in the cable connector for balanced transmission  50 . Further, the Y 1  side is the back side of the cable connector for balanced transmission  50  and the Y 2  side is the front side of the cable connector for balanced transmission  50 . 
   As shown in  FIG. 4 , the cable connector for balanced transmission  50  includes the contact assembly body  51 , a spacer member  60  that decides the contact position, a shielding cover assembly body  80  that surrounds the contact assembly body  51  and the spacer member  60 , the cable for balanced transmission  20 , a hood  100 , and an outer cover  110 . 
   [Contact Assembly body  51 ] 
   The contact assembly body  51  has a structure in which pairs of the first and second signal contact members  53  and  54  and the ground contact members  55  are alternately assembled in the X direction in a block body  52 , and further, a locking arm member  56  is assembled at the X 1  side of the contact assembly body  51  and a locking arm member  57  is assembled at the X 2  side of the contact assembly body  51 . The first signal contact member  53  is positioned at the Z 1  side and the second signal contact member  54  is positioned at the Z 2  side at the same position in the X direction. 
   As shown in  FIGS. 4 through 6 , the block body  52  is made of an electrically insulating resin and is an approximate flat rectangular parallelepiped. The block body  52  includes an approximately rectangular parallelepiped section  52   a  with many regularly formed holes into which the first and second signal contact members  53  and  54  and the ground contact members  55  are inserted, and arms  52   b  and  52   c  extending in the Y 2  direction from corresponding sides of the X direction of the approximate rectangular parallelepiped section  52   a . A space  52   d  is formed between the arms  52   b  and  52   c . Guide grooves  52   e  and  52   f  are formed at facing insides of the arms  52   b  and  52   c . The length L 1  of the guide groove  52   e  and the length L 2  of the guide groove  52   f  are different, and L 1 &gt;L 2 . The length L 1   a  is of a guide groove  52   e   1  is formed from the Y 2  side face  52   k  inside the block body  52 , and the length L 2   a  of a guide groove  52   f   1  is formed from the Y 2  side face  52   k  inside the block body  52 , where L 1   a &gt;L 2   a  (refer to  FIG. 10 ). In addition, in the X 1  and X 2  sides of the block body  52 , grooves  52   g  and  52   h , and holes  52   i  and  52   j , respectively, are formed (refer to  FIG. 6 ). 
     FIG. 11  is a diagram showing the first signal contact member  53 . In  FIG. 11 , (a) shows a plan view, (b) shows a side view, (c) shows a view looking from the Y 2  direction, and (d) shows a view looking from the Y 1  direction. As shown in  FIG. 11 , the first signal contact member  53  includes a center part  53   a  having a bulge part, a contact part  53   b  of the Y 1  side, and a first signal wire connecting part  53   c  of the Y 2  side. The first signal wire connecting part  53   c  has an L shape in its cross section, and includes a horizontal plate part  53   c   1  and a vertical side plate part  53   c   2 . In addition, a bent crank part  53   d  is formed between the first signal wire connecting part  53   c  and the center part  53   a , and the first signal wire connecting part  53   c  is slightly offset in the horizontal direction from the center part  53   a.    
     FIG. 12  is a diagram showing the second signal contact member  54 . In  FIG. 12 , (a) shows a side view, (b) shows a plan view, (c) shows a view looking from the Y 2  direction, and (d) shows a view looking from the Y 1  direction. As shown in  FIG. 12 , the second signal contact member  54  includes a center part  54   a  having a bulge part, a contact part  54   b  of the Y 1  side, and a second signal wire connecting part  54   c  of the Y 2  side. In addition, the second signal wire connecting part  54   c  has an L shape in its cross section, and includes a horizontal plate part  54   c l and a vertical side plate part  54   c   2 . In addition, a bent crank part  54   d  is formed between the second signal wire connecting part  54   c  and the center part  54   a , and the second signal wire connecting part  54   c  is slightly offset in the horizontal direction from the center part  54   a.    
   As shown in  FIG. 7 , the first signal contact member  53  and the second signal contact member  54  are respectively fitted into holes  52   p  and  52   q  of the block body  52  by being pressed from the Y 2  side. 
     FIG. 13  is a diagram showing the-ground contact member  55 . In  FIG. 13 , (a) shows a plan view, (b) shows a side view, (c) shows a bottom view, (d) shows a view looking from the Y 2  direction, and (e) shows a view looking from the Y 1  direction. As shown in  FIG. 13 , the ground contact member  55  has a plate shape. The ground contact members  55  sandwich the first and second signal contact members  53  and  54  therebetween and shield them. The ground contact member  55  includes a center part  55   a  having a bulge part, a contact part  55   b  having a fork shape of the Y 1  side, a plate part  55   c  of the Y 2  side, a drain wire connecting part  55   d , and a notch  55   e  at the Y 2  side end. The drain wire connecting part  55   d  includes three lugs  55   d   1 ,  55   d   2 , and  55   d   3  at the Z 1  and Y 2  side ends of the ground contact member  55 , and the three lugs  55   d   1 ,  55   d   2 , and  55   d   3  are alternately bent in the X 1  and X 2  directions, and as shown in  FIG. 13(   d ), form a U-letter. 
   As shown in  FIG. 8 , the ground contact member  55  is fitted into a hole  52   s  of the block body  52  by being pressed from the Y 2  side. 
   In a state where the first signal contact members  53 , the second signal contact members  54 , and the ground contact members  55  are assembled in the block body  52 , the first signal wire connecting parts  53   c , the second signal wire connecting parts  54   c , the plate parts  55   c , and the drain wire connecting parts  55   d  are arrayed in the space  52   d  (refer to  FIG. 4 ). 
     FIG. 18  is a diagram showing the locking arm member  56 . In  FIG. 18 , (a) shows a perspective view of the locking arm member  56 , (b) shows a hook  56   c  of the locking arm member  56 , (c) shows a hook  56   c A of the locking arm member  56 , and (d) shows a hook  56   c B of the locking arm member  56 . The locking arm member  57  has a structure similar to that shown in  FIG. 18 . 
   As shown in  FIGS. 4 ,  9 , and  18 , the locking arm member  56  includes a U-shaped part  56   a  at the Y 2  side, an arm  56   b  being an upper part of the U-shaped part  56   a  elongated in the Y 1  direction, a hook  56   c  at the end of the arm  56   b , and a protrusion  56   d  at the Y 2  side part of the arm  56   b . The locking arm member  56  is secured to the block body  52  by inserting an end of the U-shaped part  56   a  into a hole  52   i  and by inserting the arm  56   b  into a groove  52   g . The locking arm member  57  has the same shape as that of the locking arm member  56  and is similarly secured to the block body  52 . 
   The hooks  56   c A and  56   c B are described below. 
   [Spacer Member  60 ] 
     FIG. 14  is a perspective view showing the contact assembly body  51  and the spacer member  60 .  FIG. 15  is a perspective view showing the block body  52  and the spacer member  60 . The spacer member  60  decides positions of the first and second signal wire connecting parts  53   c  and  54   c  and the drain wire connecting parts  55   d  (refer to  FIGS. 11 ,  12 , and  13 ) without being moved in the X 1 -X 2  direction. As shown in  FIGS. 14 and 15 , the spacer member  60  is a plate-shaped member made of an electrically insulating resin and includes first grooves  61 , second grooves  62 , slits  63 , and protrusion arms  67  and  68 . 
   The first groove  61  has a shape corresponding to the shape of the first signal wire connecting part  53   c  (refer to  FIG. 11 ), and is formed in a Z 1  side face of the spacer member  60  elongated in the Y direction in the entire face thereof. 
   The second groove  62  has a shape corresponding to the shape of the second signal wire connecting part  54   c  (refer to  FIG. 12 ), and is formed in a Z 2  side face of the spacer member  60  elongated in the Y direction in the entire face thereof. 
   The first signal wire connecting part  53   c  and the second signal wire connecting part  54   c  have the same dimensions and are at the same positions in the X direction. 
   The slit  63  has a shape corresponding to the shape of the plate part  55   c  of the ground contact member  55  (refer to  FIG. 13 ), and is formed by biting into places between the adjacent two first grooves  61  and between the adjacent two second grooves  62  from the Y 1  side. A non-slit part  64  has a size corresponding to the size of the notch  55   e  of the ground contact member  55 , and is formed between the end of the slit  63  and a Y 2  side face  65  of the spacer member  60 . 
   The protrusion arm  67  protrudes by a length L 1   b  in the Y 1  direction from the X 1  side of the spacer member  60 . The protrusion arm  68  protrudes by a length L 2   b  in the Y 1  direction from the X 2  side of the spacer member  60 . The length L 1   b  of the protrusion arm  67  is different-from the length L 2   b  of the protrusion arm  68 , and L 1   b &gt;L 2   b.    
   As shown in  FIGS. 14 and 15 , the spacer member  60  is attached to the block body  52  in a manner so that the first signal contact-members  53 , the second signal contact members  54 , and the ground contact members  55  are first assembled in the block body  52 , and the protrusion arms  67  and  68  of the spacer member  60  are inserted into the end positions of the guide grooves  52   e  and  52   f , respectively, in a state where the first signal wire connecting part  53   c , the second signal wire connecting part  54   c , the plate part  55   c , and the drain wire connecting part  55   d  protrude in the space  52   d  by being arrayed. The spacer member  60  is more strongly attached to the block body  52  by inserting the protrusion arms  67  and  68  into the guide grooves  52   e  and  52   f  formed in the block body  52 , compared with a case in which the spacer member  60  is attached to the block body  52  by engaging corresponding sides of the spacer member  60  with the arms  52   b  and  52   c  of the block body  52 . 
   In  FIG. 6 , the spacer member  60  is attached to the block body  52 . As shown in  FIG. 6 , the first signal wire connecting part  53   c  is inserted into the first groove  61  and is controlled not to move in the X 1 -X 2  direction and the Z 2  direction, and the second signal wire connecting part  54   c  is inserted into the second groove  61  and is controlled not to move in the X 1 -X 2  direction and the Z 1  direction. As shown in  FIG. 10 , in parts protruding to the space  52   d  of the ground contact member  55 , the plate part  55   c  is inserted into the slit  63 , and as shown in  FIG. 8 , the notch  55   e  is engaged in the non-slit part  64 ; therefore, the drain wire connecting part  55   d  is controlled not to move in the X 1 -X 2  direction and the Z 1 -Z 2  direction. Consequently, the plate part  55   c  and the drain wire connecting part  55   d  of the ground contact member  55  do not contact the first and second wire connecting parts  53   c  and  54   c.    
   In addition, as shown in  FIG. 10 , the lengths L 1   a  and L 2   a  of the guide grooves  52   e   1  and  52   f   1  formed inside the block body  52  have a relation L 1   a &gt;L 2   a , and the lengths L 1   b  and L 2   b  of the protrusion arms  67  and  68  have the relation L 1   b &gt;L 2   b . Therefore, when it is attempted to insert the spacer member  60  in an inverted direction of its right and left sides, the spacer member  60  is prevented from being inserted. That is, by utilizing a structure in which the spacer member  60  is strongly attached to the block body  52 , the spacer member  60  is prevented from being attached in the wrong direction. 
   [Connection of Pair of Wires  21 ] 
   As shown in  FIG. 6 , from the end of the pair of wires  21 , the first and second covered signal wires  22 - 1  and  22 - 2  and the drain wire  25  are extended, and the covers at the tips of the first and second covered signal wires  22 - 1  and  22 - 2  are removed and first and second signal wires  23 - 1  and  23 - 2  being core wires are naked and exposed. The first signal wire  23 - 1  pairs up with the second signal wire  23 - 2 . 
   As shown in  FIGS. 5A and 6 , the first signal wire  23 - 1  is connected by soldering to the first signal wire connecting part  53   c  whose position is controlled by the first groove  61 , and the second signal wire  23 - 2  is connected by soldering to the second signal wire connecting part  54   c  whose position is controlled by the second groove  62 . The drain wire  25  is connected by soldering to the drain wire connecting part  55   d  whose position is controlled by the slit  63 . In  FIGS. 5A and 5B , the reference number  70  is solder. As shown in  FIG. 5B , since the first and second signal wire connecting parts  53   c  and  54   c  are L-shaped and have a corner, the first and second signal wires  23 - 1  and  23 - 2  are soldered to the first and second signal wire connecting parts  53   c  and  54   c , respectively, in a manner so that positions inside the corners to which the first and second signal wires  23 - 1  and  23 - 2  are pushed are uniquely decided. In addition, since the drain wire connecting part  55   d  is U-shaped, the drain wire  25  is soldered to the drain wire connecting part  55   d  in a manner so that a position where the drain wire  25  is pushed is uniquely decided. 
   As described above, the first and second signal wires  23 - 1  and  23 - 2  are directly connected to the first and second signal contact members  53  and  54 , respectively, without being connected via a relay board. Therefore, the crosstalk characteristic of the cable connector for balanced transmission  50  of the present invention is improved, compared with the conventional cable connector for balanced transmission. 
   The connecting method is not limited to soldering, and other connecting methods such as welding can be used. 
   In addition, in  FIG. 5B , looking from the Y 2  side, the respective positional relationships between the soldered first and second signal wires  23 - 1  and  23 - 2  and the contact parts  53   b  and  54   b  are shown; further, the positional relationship between the drain wire  25  and the contact part  55   b  is shown. In addition, as described above in  FIG. 11 , since the first signal wire connecting part  53   c  is slightly offset in the horizontal direction for the center part  53   a  by the bent crank part  53   d , as shown in  FIG. 5B , the soldered first signal wire  23 - 1  is arrayed with the contact part  53   b  in the Y 1 -Y 2  direction. That is, the center line of the soldered first signal wire  23 - 1  coincides with the center line of the contact part  53   b . Similarly, as described above in  FIG. 12 , since the second signal wire connecting part  54   c  is slightly offset in the horizontal direction for the center part  54   a  by the bent crank part  54   d , as shown in  FIG. 5B , the soldered second signal wire  23 - 2  is arrayed with the contact part  54   b  in the Y 1 -Y 2  direction. That is, the center line of the soldered second signal wire  23 - 2  coincides with the center line of the contact part  54   b . As shown in  FIG. 5B , since the drain wire connecting part  55   d  is U-shaped, the drain wire  25  is arrayed with the contact part  55   b  in the Y 1 -Y 2  direction. 
   In  FIGS. 7 and 8 , the reference number  71  is a sealing resin part, and the part of the space  52   d  remaining after connecting the cable for balanced transmission  20  to the contact assembly body  51  is filled with the sealing resin part  71 , so that the sealing resin part  71  covers the first and second signal wires  23 - 1  and  23 - 2 , the drain wire  25 , the first and second signal wire connecting parts  53   c  and  54   c , and the drain wire connecting part  55   d . The spacer member  60  is secured to the block body  52  by the sealing resin part  71 . Further, the first and second signal wires  23 - 1  and  23 - 2 , the drain wire  25 , the first and second signal wire connecting parts  53   c  and  54   c , and the drain wire connecting part  55   d  are secured to the block body  52  by the sealing resin part  71 . By the sealing resin part  71 , the connections of the first and second signal wires  23 - 1  and  23 - 2  to the first and second signal wire connecting parts  53   c  and  54   c  are strengthened, and the connection of the drain wire  25  to the drain wire connecting part  55   d  is also strengthened. 
   [Shielding Cover Assembly Body  80 ] 
   As shown in  FIGS. 4 and 7  through  9 , the shielding cover assembly body  80  is composed of a first shielding cover  81  of the Z 1  side and a second shielding cover  90  of the Z 2  side. The first and second shielding covers  81  and  90  are formed by a metal plate by pressing. The contact assembly body  51  and the spacer member  60  are surrounded by the first and second shielding covers  81  and  90  when assembled. 
   As shown in  FIG. 9 , the hook  56   c  and the protrusion  56   d  of the locking arm member  56  and the hook  57   c  and the protrusion  57   d  of the locking arm member  57  protrude in the Z 1  direction from openings of the first shielding cover  81 . 
   As shown in  FIG. 4 , in the first shielding cover  81 , protrusions  82  and  83  protruding in the Z 1  direction are formed. 
   The end of the cable for balanced transmission  20  is clamped by a ring part  85  at the Y 2  side of the first shielding cover  81 . 
   [Hood  100  and Outer Cover  110 ] 
   As shown in  FIG. 4 , the hood  100  reinforcing the end of the cable connector for balanced transmission  50  is a soft component made of a resin and includes stretching parts  101  and  102  stretched like wings in the X 1  and X 2  directions at the Y 1  end. 
   Further, as shown in  FIG. 4 , the outer cover  110  is a single soft component made of resin, has an approximate box shape whose Y 1  and Y 2  sides are openings, and includes an operating section  111  like a flap shape in the Z 1  side face and notches  112  and  113  at the Y 1  side of the operating section  111 . 
   Next, an inserting method of the cable for balanced transmission  20  is explained. 
   First, the cable for balanced transmission  20  is inserted into the hood  100  and the outer cover  110 , and tips of the cable for balanced transmission  20  are soldered to the first and second signal wire connecting parts  53   c  and  54   c  and the drain wire connecting parts  55   d  whose positions are decided by the spacer member  60  and the block body  52 . Next, the hood  100  is positioned near the ring part  85  of the first shielding cover  81  by being moved along the cable for balanced transmission  20 . Then, the outer cover  110  is moved along the cable for balanced transmission  20 , and the cable for balanced transmission  20  is engaged in the shielding cover assembly body  80  via the ring part  85  from the Y 2  side. 
     FIG. 16  is a perspective view showing a tip part of the cable connector for balanced transmission  50 . As shown in  FIGS. 4 ,  7 , and  16 , the protrusions  82  and  83  of the first shielding cover  81  are respectively inserted into the notches  112  and  113  of the outer cover  110  and the shielding cover assembly body  80  is prevented from being moved in the Y 2  direction.  FIG. 17  is a perspective view showing the cable connector for balanced transmission  50  to which the hood  100  and the outer cover  110  are attached. As shown in  FIG. 17 , the stretching parts  101  and  102  of the hood  100  are stopped by the outer cover  110  and the hood  100  is prevented from being moved in the Y 2  direction. 
   As shown in  FIG. 9 , the operating section  111  of the outer cover  110  is positioned right above the protrusions  56   d  and  57   d  of the locking arm members  56  and  57 . Therefore, when the operating section  111  is pushed, the protrusions  56   d  and  57   d  are pushed, the arms  56   b  and  57   d  are bent, and the hooks  56   c  and  57   c  are pushed down. With this, the cable connector for balanced transmission  50  can be unlocked from a connector of an apparatus by unlocking the locking arm members  56  and  57 . 
   In this, the first signal contact member  53  can dispose its contact part at the Y 2  side, the second signal contact member  54  can dispose its contact part at the Y 2  side, and the ground contact member  55  can dispose its fork-shaped contact part at the Y 2  side; further, a relay board can be used instead of using the spacer member  60  and the relay board is engaged by the guide grooves  52   e  and  52   f . This structure is possible. 
   [Hook  56   c  of Locking Arm Member  56 ] 
   Referring to  FIG. 18 , the hook  56   c  of the locking arm member  56  is explained in detail. As shown in  FIG. 18(   b ), the hook  56   c  has a shape in which an edge  56   e  of the hook  56   c  at the Y 2  side has an angle a being an acute angle between the Y axis and the edge  56   e . In other words, the edge  56   e  is slanted in the Y 2  direction. 
   The cable connector for balanced transmission  50  is connected to a connector of an apparatus and is locked by inserting the hook  56   c  into a slit of the connector of the apparatus. The sustaining strength of the locking state is high when the cable connector for balanced transmission  50  is connected to a connector on a circuit board of an apparatus with the angle a being an acute angle (refer to  FIG. 32 ). 
   As described above, in  FIG. 18(   c ), the hook  56   c A is shown, and in  FIG. 18(   d ), the hook  56   c B is shown. The hook  56   c A has a thicker shape in the Y 1  direction than the hook  56   c  shown by a broken line. The hook  56   c B has a thicker shape in the Z 2  direction than the hook  56   c  shown by the broken line. The strength of the hooks  56   c A and  56   c B is greater than that of the hook  56   c.    
   Second Embodiment 
     FIG. 19  is a perspective view of a cable connector for balanced transmission  50 A according to a second embodiment of the present invention. The cable connector for balanced transmission  50 A includes an outer cover  110 A and a hood  100 A which are formed by potting a resin and an operating section  111 A reinforced by a reinforcing plate member  200 . 
   The cable connector for balanced transmission  50 A is manufactured by the following processes. In  FIG. 19 , (a), (b), and (c) show the processes. 
   First, a cable connector main body  190 A is assembled by surrounding the contact assembly body  51  (not shown) and the spacer member  60  (not shown) with the use of the shielding cover assembly body  80  and further by clamping the end of the cable for balanced transmission  20  with the ring part  85 . These processes are the same as those in the first embodiment. 
   Next, as shown in  FIG. 19(   a ), a reinforcing plate member  200  covers the protrusions  56   d  and  57   d  of the locking arm member  56  and  57  (refer to  FIG. 9) , and a component  210  for forming a U-shaped slit runs along three sides of the reinforcing plate member  200 , and further, a partitioning component  215  runs along the fourth side of the plate member  200 . 
   Then, as shown in  FIG. 19(   b ), the outer cover  110 A and the hood  100 A are formed in an integrated manner by applying potting of a resin so that the shielding cover assembly body  80  is covered. In this, the outer cover  110 A covers the cable connector main body  190 A and the hood  100 A covers the ring part  85 . 
   Further, as shown in  FIG. 19(   c ), the component  210  is removed. With this, a U-shaped slit  220  is formed around the operating section  111 A, and the operating section  111 A is formed by being reinforced by the reinforcing plate member  200 . 
   Third Embodiment 
     FIG. 20  is a perspective view of a cable connector for balanced transmission  50 B according to a third embodiment of the present invention. The cable connector for balanced transmission  50 B includes an outer cover  110 B and a hood  100 B which are formed by outsert molding and an operating section  301  formed by an operating section member  300 .  FIG. 21  is a cross-sectional view of a part of the cable connector for balanced transmission  50 B shown in  FIG. 20 . 
   The cable connector for balanced transmission  50 B is manufacture by the following processes. In  FIG. 20 , (a), (b), and (c) show the processes. 
   As shown in  FIG. 20(   a ), the operating section member  300  is a plate-shaped member and includes the operating section  301  at the Y 1  side and two openings  302  and  303  at the Y 2  side. In addition, a shielding cover assembly body  80 B includes two protrusions  312  and  313  in the upper face. The height “a” of the protrusions  312  and  313  is less than the thickness “t” of the operating section member  300  (refer to  FIG. 21) . 
   As shown in  FIG. 20(   b ), first, a cable connector main body  190 B is assembled by surrounding the contact assembly body  51  (not shown) and the spacer member  60  (not shown) with a shielding cover assembly body  80 B and further by clamping the end of the cable for balanced transmission  20  with the ring part  85 . These processes are the same as those in the first embodiment. The shielding cover assembly body  80 B is composed of a first shielding cover  81 B and a second shielding cover  90 B. 
   As shown in  FIG. 20(   b ), the operating section member  300  is attached on the shielding cover assembly body  80 B by engaging the openings  302  and  303  with the protrusions  312  and  313 , respectively, in a manner so that the operating section member  300  covers the protrusions  56   d  and  57   d  of the locking arm members  56  and  57  (refer to  FIG. 9) . 
   Next, the above semi-assembled item is placed in a forming die and outsert molding is applied. As shown in  FIG. 20(   c ), the outer cover  110 B and the hood  100 B are formed in an integrated manner by the outsert molding. In this, the outer cover  110 B covers the cable connector main body  190 B and the hood  100 B covers the ring part  85 . 
   When taking out the above outsert molding item from the forming die, the cable connector for balanced transmission  50 B is completed. 
   In the outsert molding, a resin does not cover the upper face and edge parts of the operating section  301  of the operating section member  300 . As shown in  FIG. 21 , a resin part  110 B a  of the outer cover  110 B covers the Y 2  side part of the operating section member  300  and a resin part  110 B b  of the outer cover  110 B fills the openings  302  and  303 . The operating section member  300  is secured on the shielding cover assembly body  80 B by the resin parts  110 B a  and  110 B b.    
   Fourth Embodiment 
     FIG. 22  is an exploded perspective view of a cable connector for balanced transmission  50 C according to a fourth embodiment of the present invention.  FIG. 23  is a perspective view of the cable connector for balanced transmission  50 C. In  FIG. 23 , (a) shows a view looking from the Z 2  and Y 2  sides and (b) shows a view looking from the Z 1  and Y 1  sides.  FIG. 24  is a perspective view of the cable connector for balanced transmission  50 C with the shielding cover assembly body  80 B removed. In  FIG. 24 , (a) shows a view looking from the Z 2  and Y 2  sides and (b) shows a view looking from the Z 1  and Y 1  sides. 
   In the cable connector for balanced transmission  50 C according to the fourth embodiment, in addition to the cable connector for balanced transmission  50 B according to the third embodiment, an inner cap  400  is newly added. The inner cap  400  prevents resin from flowing into the shielding caver assembly body  80 B when the outer cover  110 B and the hood  100 B are formed by the outsert molding. 
   The shielding cover assembly body  80 B has an opening into which the cable for balanced transmission  20  is inserted at the Y 2  side. Therefore, it is likely that resin flows into the shielding cover assembly body  80 B from the Y 2  side at the time of the outsert molding. In order to avoid this, the inner cap  400  is disposed at the Y 2  side of the shielding cover assembly body  80 B. 
     FIG. 25  is a perspective view of the inner cap  400 .  FIG. 26  is an exploded perspective view of the inner cap  400  and the shielding cover assembly body  80 B. As shown in  FIG. 26 , the inner cap  400  has a structure in which a first inner cap half  401  of the Z 1  side and a second inner cap half  402  of the Z 2  side are combined and both halves are made of molded resin. The inner cap  400  is disposed at the Y 2  end in the shielding cover assembly body  80 B, that is, at the part through which the cable for balanced transmission  20  is inserted in the shielding cover assembly body  80 B, and the inner cap  400  closes a gap at the Y 2  end between the shielding cover assembly body  80 B and the cable for balanced transmission  20 . 
   As shown in  FIG. 26 , the second inner cap half  410  is an approximate U-shaped member and includes a base part  411 , and rising parts  412  and  413  rising from the X 1  and X 2  sides, respectively, of the base part  411  in the Z 1  direction. A space  414  is formed between the rising parts  412  and  413 . Protrusions  415  are formed at both end faces of the X 1  and X 2  sides of the base part  411 . Concave parts  416  and  417  engaging the spacer member  60  (refer to  FIG. 22 ) are formed at the Y 1  sides of the rising parts  412  and  413 , respectively. 
   As shown in  FIG. 25 , the first inner cap half  401  includes an upper plate part  402 , side plate parts  403  and  404  of the X 1  and X 2  sides, respectively, and a back plate part  405  of the Y 2  side(refer to  FIG. 26 ). The side plate part  403  includes a step part  403   a  in the middle, a notch  403   b  at the Z 2  end, and ribs  403   c  and  403   d  on the outer face; the side plate part  404  includes a step part  404   a  in the middle, a notch  404   b  at the Z 2  end, and ribs  404   c  and  404   d  on the outer face. A window  405   b  having an approximate semicircular shape is formed in the back plate part  405  (refer to  FIG. 26 ). 
   The protrusions  415  of the second inner cap half  410  are inserted into the notches  403   b  and  404   b  by being pressed. The ribs  403   c  and  403   d  and the ribs  404   c  and  404   d  are elongated as straight lines in the Z 1 -Z 2  direction formed for the approximate entire lengths on the side plates  403  and  404 , respectively. The ribs  403   c  and  404   c  are formed so that the ribs  403   c  and  404   c  press the inside walls of the second shielding cover  90 B. The ribs  403   d  and  404   d  are formed so that the ribs  403   d  and  404   d  press the inside walls of the first shielding cover  81 B. 
   A cable connector main body  190 C is assembled by surrounding the contact assembly body  51  and the spacer member  60  with the shielding cover assembly body  80 B, in which the inner cap  400  is formed and by further clamping the end of the cable for balanced transmission  20  with the ring part  85 . 
   The cable connector for balanced transmission  50 C is formed by forming the outer cover  110 B and the hood  100 B on the cable connector main body  190 C by outsert molding. 
     FIG. 27  is a perspective view showing the inner cap  400  and the first shielding cover  81 B. In  FIG. 27 , (a) shows a first process of assembling the inner cap  400  and the first shielding cover  81 B, and (b) shows a second process of assembling the inner cap  400  and the first shielding cover  81 B. 
   As shown in  FIGS. 22 through 27 , the first inner cap half  401  is pushed into the first shielding cover  81 B, the contact assembly body  51  to which the tips of the cable for balanced transmission  20  are connected is assembled in the first inner cap half  401 , and the inner cap  400  is assembled by combining the second inner cap half  410  with the first inner cap half  401 . Further, the second shielding cover  90 B is engaged with the first shielding cover  81 B by covering the second inner cap half  410 . In addition, the end of the cable for balanced transmission  20  is clamped by the ring part  85 . With the above processes, the cable connector main body  190 C is assembled. 
   In the middle of the assembly of the cable connector main body  190 C, the protrusions  415  of the second inner cap half  410  are inserted into the notches  403   b  and  404   b  of the first inner cap half  401 . Since the cable for balanced transmission  20  before being clamped is tentatively secured to the inner cap  400 , the cable connector main body  190 C can be easily assembled. 
     FIG. 28  is a schematic diagram showing where gaps between the X 1  and X 2  sides of the inner cap  400  and the shielding cover assembly body  80 B are closed. In  FIG. 28 , (a) shows a diagram in which the cable connector main body  190 C is viewed from the Y 2  side, (b) shows a cross-sectional view of the cable connector main body  190 C shown in  FIG. 28(   a ) along line B—B of  FIG. 28(   a ), and ( c ) shows a cross-sectional view of the cable connector main body  190 C shown in  FIG. 28(   a ) along line C—C of  FIG. 28(   a ). 
   As shown in (a) and (c) of  FIG. 28 , gaps  440  between the X 1  and X 2  sides of the inner cap  400  ( 401 ) and both side plates  96  of the second shielding cover  90 B are closed by pressing the ribs  403   c  and  404   c  against the inside walls of the side plates  96  of the second shielding cover  90 B. As shown in (a) and (b) of  FIG. 28 , gaps  430  between the X 1  and X 2  sides of the inner cap  400  ( 401 ) and both side plates  86  of the first shielding cover  81 B are closed by pressing the ribs  403   d  and  404   d  against the inside walls of the side plates  86  of the first shielding cover  81 B. The space  414  is filled with plural pairs of wires  21 . 
   Therefore, resin is prevented from flowing into the inside of the shielding cover assembly body  80 B from the Y 2  side at the time of outsert molding by the existence of the inner cap  400 . 
   As shown in  FIGS. 25 and 28(   a ), spaces  421  and  422  are formed inside the inner cap  400  at the X 1  and X 2  sides. As shown in  FIG. 24(   b ), the U-shaped parts  56   a  and  57   a  of the locking arm members  56  and  57  are fitted into the spaces  421  and  422 . 
     FIG. 29  is a perspective view of a cable connector main body  190 D in which the relay board  12  is used. The relay board  12  is shown in  FIG. 1 . Edges of the relay board  12  are inserted to the concave parts  416  and  417  of the rising parts  412  and  413  (refer to  FIG. 26 ) of the second inner cap half  410 . With this, the relay board  12  is supported. 
   Fifth Embodiment 
     FIG. 30  is a diagram showing a part of a cable connector for balanced transmission  50 D according to a fifth embodiment of the present invention. In  FIG. 30 , (a) shows a perspective view of the part of the cable connector for balanced transmission  50 D, and (b) shows a state in which the first signal contact member  53 , the second signal contact member  54 , the ground contact member  55 , and a ground contact member  55 D are arrayed. 
   As shown in  FIG. 30 , in a contact assembly body  51 D, the ground contact member  55  is disposed at one side of the first signal contact member  53  and the second signal contact member  54 , and the ground contact member  55 D is disposed at the other side of the first signal contact member  53  and the second signal contact member  54  in the block body  52 . The ground contact member  55 D has the same shape as that of the ground contact member  55 , exceptionally that the ground contact member  55 D is disposed upside down. 
   As shown in  FIG. 30 , the ground contact members  55  and  55 D are alternately arrayed. The ground contact member  55  has the drain wire connecting part  55   d  at the Z 1  side, and the ground contact member  55 D has a drain wire connecting part  55 Dd at the Z 2  side. 
   As shown in  FIG. 30(   b ), the drain wire connecting parts  55   d  and  55 Dd are alternately arrayed up and down. Therefore, the interval LX between the drain wire connecting parts  55   d  ( 55 Dd) becomes twice as long as the interval of the case in which only the drain wire connecting parts  55   d  are arrayed. Consequently, it becomes easy to solder the tips of the pair of wires  21  to the drain wire connecting parts  55   d  ( 55 Dd). 
   Sixth Embodiment 
     FIG. 31  is a perspective view of a connector for printed circuit board  500  according to a sixth embodiment of the present invention. In  FIG. 31 , a connector main body  501 , a metal gasket  530 , and a shielding member  540  are shown.  FIG. 32  is a perspective view of the Y 2  side of the connector main body  501  with the metal gasket  530 .  FIG. 33  is a diagram showing a state in which the connector for printed circuit board  500  is mounted on a printed circuit board  550 . 
   As shown in  FIGS. 31 through 33 , the connector for printed circuit board  500  has a structure in which the metal gasket  530  and the shielding member  540  are attached to the connector main body  501 . The connector for printed circuit board  500  is mounted on an edge part of the printed circuit board  550  of an electronic apparatus (not shown) and is connected to the connector for balanced transmission  50  ( 50 A through  50 D). 
   The connector main body  501  has a structure in which a contact assembly body  502  is assembled in the shielding body  510 . The connector main body  501  is a right angle type. 
   The contact assembly body  502  has a structure in which first and second signal contact members  504  and  505  and grand contact members  506  are arrayed in a block  503  made of an electrically insulating material. 
   The shielding body  510  is made of a metal plate having a shape surrounding the contact assembly body  502  and has legs inserting to holes of the printed circuit board  550 . 
   The shielding body  510  has plate springs  512  and slits  513  in relation with the cable connector for balanced transmission  50  ( 50 A to  50 D). The plate springs  512  contact the shielding cover assembly body  80  ( 80 B) of the cable connector for balanced transmission  50  ( 50 A to  50 D) when the cable connector for balanced transmission  50  ( 50 A to  50 D) is connected to the connector for printed circuit board  500 . Further, when the cable connector for balanced transmission  50  ( 50 A to  50 D) is connected to the connector for printed circuit board  500 , the hooks  56   c  and  57   c  of the locking arm members  56  and  57  are engaged in the slits  513 , then moving of the cable connector for balanced transmission  50  ( 50 A to  50 D) is stopped. 
   The shielding body  510  has flanges  514 ,  515 ,  516 , and  517  which protrude in the up and down and right and left directions from the ends of the opening of the Y 2  side in relation with the metal gasket  530 . The flanges  514  and  515  have slits  518  in their right and left sides. 
   The shielding body  510  has slits  519  in the right and left side plates in relation with the shielding member  540 . 
   The metal gasket  530  is composed of a rectangular frame  531  made of a metal plate. Plural contacting parts  534  being plate springs are formed in an upper side part  532  and a lower side part  533  of the rectangular frame  531 . In addition, lugs  535  are formed in the upper side part  532  and the lower side part  533  so that the lugs  535  protrude in the Y 1  direction. The lug  535  has a rising part  536 . 
   The lugs  535  of the metal gasket  530  are inserted into the slits  518  of the shielding body  510 . As shown in an enlarged part of  FIG. 33 , the metal gasket  530  is secured to the front of the flanges  514  through  517  so that the rising parts  536  of the lugs  535  passing through the slits  518  stop against the back faces of the flanges  514  and  515 . 
   As shown in  FIG. 31 , the shielding member  540  is an approximate box-shaped member made of a metal having a size corresponding to the connector main body  501 , and has an upper plate part  541 , a right side plate part  542 , a left side plate part  543 , and a back plate part  544  at the Y 1  side. A protrusion  545  is formed inside the right side plate part  542  and the left side plate part  543 . The shielding member  540  is attached to the connector main body  501  mounted on the printed circuit board  550 , and covers the upper side, the right and left sides, and the back side of the connector main body  501 . 
   The connector main body  501  having the metal gasket  530  is mounted on the printed circuit board  550  and the shielding member  540  is attached to the connector main body  501 . Further, the printed circuit board  550  is attached inside an electronic apparatus, as shown in  FIG. 33 . The connector for printed circuit board  500  is disposed at an opening  561  of a panel of the electronic apparatus. The contacting parts  534  contact the back face of the panel  560  by being pressed. 
   When the connector for printed circuit board  500  is in use, since the shielding member  540  is electrically connected to the panel  560  of the electronic apparatus via the shielding body  510  and the metal gasket  530 , the electric potential of the shielding member  540  is ground electric potential. The shielding member  540  covers the upper side, the right and left sides, and the back side of the connector main body  501 ; therefore, the contact assembly body  502  is well shielded. Consequently, the connector for printed circuit board  500  has an excellent EMI (electro-magnetic interference) characteristic; therefore, emission of noise is prevented, and may not be influenced by outside noise. 
   Further, the present invention is not limited to these embodiments, but various variations and modifications may be made without departing from the scope of the present invention. 
   The present application is based on Japanese Priority Application No. 2005-160285 filed on May 31, 2005, and Japanese Priority Application No. 2005-375813 filed on Dec. 27, 2005, with the Japanese Patent Office, the entire contents of which are hereby incorporated by reference.