Abstract:
An electrical connector comprises a plurality of conductive contacts arranged in a matrix pattern with a space left from one another and a conductive ground member disposed in the space. The ground member comprises a plurality of first ground plates and a plurality of second ground plates combined with the first ground plates. Each of the first ground plates has a plurality of first slit portions. Each of the second ground plates has a plurality of second slit portions. The contacts are received in one-to-one correspondence in a plurality of contact receiving portions defined by combining the first and the second ground plates in a lattice fashion in the state that the second and the first ground plates are inserted in the first and the second slit portions, respectively. Each of the first slit portions has at least one contacting portion contacted with the second ground plate inserted therein.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     This invention relates to an electrical connector for use in transmitting a signal and, in particular, to an electrical connector for use in transmitting a high-speed signal.  
         [0002]     For example, an electrical connector of the type is disclosed in Japanese PatentApplication Publication (JP-A) No. 2002-117938 (Reference 1). The electrical connector comprises a plurality of pin contacts, a housing holding the contacts, and a plurality of ground plates.  
         [0003]     The ground plates includes first and second ground plates. One of the first and the second ground plates has a first contacting portion connected to at least one of the contacts and a second contacting portion connecting the first and the second ground plates to each other. The first ground plate is placed between adjacent ones of the contacts. The second ground plate extends in a direction intersecting with the first ground plate and is placed between adjacent ones of the contacts.  
         [0004]     Another electrical connector disclosed in Japanese Patent Application Publication (JP-A) No. H09-330770 (Reference 2) comprises a plurality of ground terminals and a plurality of signal terminals disposed in a staggered arrangement. Each of the ground terminals has a cross-shaped section. Each of cross protrusions of the ground terminal extend between adjacent ones of the signal terminals. With this structure, each signal terminal is surrounded by four ground terminals around the signal terminal so that a pseudo coaxial line is formed.  
         [0005]     In the electric connector disclosed in Reference 1, the ground plates are used to prevent occurrence of crosstalk between the contacts. However, it is difficult to completely surround and shield the contacts.  
         [0006]     In the electrical connector disclosed in Reference 2, the pseudo coaxial line is formed so as to completely shield the signal terminal. In order to form such a coaxial structure, however, the electrical connector inevitably has a complicated configuration and requires an increased number of parts.  
       SUMMARY OF THE INVENTION  
       [0007]     It is an object of this invention to provide an electrical connector which is capable of forming a pseudo coaxial line in a simple structure so as to reduce occurrence of crosstalk between contacts and to prevent degradation of transmission characteristics and which requires a reduced number of parts.  
         [0008]     According to this invention, there is provided an electrical connector comprising a plurality of conductive contacts arranged in a matrix pattern with a space left from one another, a conductive ground member disposed in the space, and an insulator holding the contacts and the ground member, wherein: 
        the ground member comprises a plurality of first ground plates and a plurality of second ground plates combined with the first ground plates;     each of the first ground plates having a first side and a first opposite side opposite to the first side and a plurality of first slit portions extending from the first side towards the first opposite side;     each of the second ground plates having a second side and a second opposite side opposite to the second side and a plurality of second slit portions extending from the second side towards the second opposite side;     the contacts being received in one-to-one correspondence in a plurality of contact receiving portions defined by combining the first and the second ground plates in a lattice fashion in the state that the second ground plates are inserted in the first slit portions while the first ground plates are inserted in the second slit portions;     each of the first slit portions having at least one contacting portion contacted with the second ground plate inserted therein.       
 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0014]      FIG. 1  is a perspective view of a connector according to a first embodiment of this invention, together with a mating connector to be coupled and connected thereto;  
         [0015]      FIG. 2  is a perspective view of an assembly of first and second ground plates of the connector illustrated in  FIG. 1 ;  
         [0016]      FIG. 3  is an enlarged plan view of the first ground plate illustrated in  FIGS. 1 and 2 ;  
         [0017]      FIG. 4  is an enlarged plan view of a first slit portion of the first ground plate illustrated in  FIG. 3 ;  
         [0018]      FIG. 5  is an enlarged plan view of the second ground plate illustrated in  FIGS. 1 and 2 ;  
         [0019]      FIG. 6  is an enlarged plan view of a second slit portion of the second ground plate illustrated in  FIG. 5 ; and  
         [0020]      FIG. 7  is an enlarged plan view of a first slit portion of a first ground plate of a connector according to a second embodiment of this invention. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0021]     Now, description will be made of an electrical connector according to this invention with reference to the drawing.  
         [0022]     Referring to  FIGS. 1 and 2 , a connector  1  according to a first embodiment of this invention comprises a plurality of conductive contacts (signal contacts)  11  arranged in a matrix fashion, i.e., in a vertical direction and in a horizontal direction, with a predetermined space left from one another, a ground member  12  arranged between adjacent ones of the contacts with a preselected space left from each contact, and an insulator  17  holding the contacts  11  and the ground member  12 .  
         [0023]     Each of the contacts  11  in this embodiment is a pin contact for signal transmission and reception. The ground member  12  comprises a plurality of first ground plates  13  and a plurality of second ground plates  15 . Each of the first ground plates  13  is formed as an elongate plate by punching a thin conductive plate using a punch press. Likewise, each of the second ground plate  15  is formed by the similar process as an elongate plate.  
         [0024]     In this embodiment, the first ground plates  13 , eight in number, are arranged in parallel to one another with the predetermined space left from one another in the vertical direction, as illustrated in  FIGS. 1 and 2 . Likewise, the second ground plates  15 , eight in number, are arranged in parallel to one another with the predetermined space left from one another in the horizontal direction. The first and the second ground plates  13  and  15  are combined and coupled to be perpendicular to each other to form an assembly as the ground member  12 .  
         [0025]     When the first and the second ground plates  13  and  15  are combined as illustrated in  FIGS. 1 and 2 , a plurality of contact accommodating portions  21 , forty-nine in number, are formed in a lattice fashion to be adjacent to one another in the vertical and the horizontal directions. The contact accommodating portions  21  are shielded from one another by the first and the second ground plates  13  and  15 . Each of the contact accommodating portions  21  has a generally rectangular shape if the connector  1  in  FIG. 1  is seen from a front side.  
         [0026]     Each of the contact accommodating portions  21  extends from the front side of the connector  1  towards a rear side as an elongate cylinder. In each contact accommodating portions  21 , each single contact  11  is disposed.  
         [0027]     Referring to  FIG. 3 , each of the first ground plates  13  illustrated in  FIGS. 1 and 2  has opposite surfaces as first plate surfaces  13   f  (only one being illustrated in the figure) and a first side  13   a  as one side parallel to a longitudinal direction of the first ground plate  13  and a first opposite side  13   b  as the other side opposite to the first side  13   a.    
         [0028]     The first ground plate  13  is provided with a plurality of first slit portions  13   s  each of which is formed as a groove cut between the first plate surfaces  13   f . Each of the first slit portions  13   s  extends from the first side  13   a  towards the first opposite side  13   b  of the first ground plate  13 . The first slit portions  13  are arranged at predetermined intervals in the longitudinal direction of the first ground plate  13 .  
         [0029]     On the first opposite side  13   b , a plurality of first ground terminal portions  13   u  are formed and extend from the first opposite side  13   b  outward of the first plate surfaces  13   f.    
         [0030]     Referring to  FIG. 4 , each of the first slit portions  13   s  will be described in detail.  
         [0031]     The first slit portion  13   s  has a pair of first slit edges  13   y  linearly extending in a direction perpendicular to the first side  13   a  and a plurality of first contacting portions  13   z  arcuately protruding from the first slit edges  13   y  inward of the first slit portion  13   s.    
         [0032]     The first slit edges  13   y  are faced to each other in a direction parallel to the first side  13   a  (i.e., in the longitudinal direction of the first ground plate  13 ) and are spaced from each other to leave a predetermined gap. The gap between the first slit edges  13   y  is substantially equal to the thickness of the second ground plate  15 . The first contacting portions  13   z  are formed alternately on the first slit edges  13   y.    
         [0033]     The first slit portion  13   s  has a pair of first slant edges  13   p  formed on the first slit edges  13   y  at portions adjacent to the first side  13   a  so that the first slit  13   s  is widened from the first slit edges  13   y  towards the first side  13   a . When the first and the second ground plates  13  and  15  are combined with each other, the first contacting portions  13   z  are brought into contact with second plate surfaces  15   f  of the second ground plate  15 .  
         [0034]     Referring to  FIG. 5 , each of the second ground plates  15  illustrated in  FIGS. 1 and 2  has opposite surfaces as the second plate surfaces  15   f  (only one being illustrated in the figure) and a second side  15   a  as one side parallel to a longitudinal direction of the second ground plate  15  and a second opposite side  15   b  as the other side opposite to the second side  15   a . The second ground plate  15  is provided with a plurality of second slit portions  15   s  each of which is formed as a groove cut between the second plate surfaces  15   f . Each of the second slit portions  15   s  extends from the second side  15   a  towards the second opposite side  15   b  of the second ground plate  13 . The second slit portions  15  are arranged at predetermined intervals in the longitudinal direction of the second ground plate  15 .  
         [0035]     On the second opposite side  15   b , a plurality of second ground terminal portions  15   u  are formed and extend from the second opposite side  15   b  outward of the second plate surfaces  15   f.    
         [0036]     Referring to  FIG. 6 , each of the second slit portions  15   s  will be described in detail.  
         [0037]     The second slit portion  15   s  has a pair of second slit edges  15   y  linearly extending in a direction perpendicular to the second side  15   a  and a plurality of second contacting portions  15   z  arcuately protruding from the second slit edges  15   y  inward of the second slit portion  15   s.    
         [0038]     The second slit edges  15   y  are faced to each other in a direction parallel to the second side  15   a  (i.e., in the longitudinal direction of the second ground plate  15 ) and are spaced from each other to leave a predetermined gap. The gap between the second slit edges  15   y  is substantially equal to the thickness of the first ground plate  13 . The second contacting portions  15   z  are formed alternately on the second slit edges  15   y.    
         [0039]     The second slit portion  15   s  has a pair of second slant edges  15   p  formed on the second slit edges  15   y  at portions adjacent to the second side  15   a  so that the second slit  15   s  is widened from the second slit edges  15   y  towards the second side  15   a.    
         [0040]     When the first and the second ground plates  13  and  15  are combined with each other, the second contacting portions  15   z  are brought into contact with the first plate surfaces  13   f  of the first ground plate  13 .  
         [0041]     Turning back to  FIG. 1 , the insulator  17  has a pair of frame portions  17   a  faced to each other and a base plate portion  17   b  connecting the frame portions  17   a . The frame portions  17   a  extends from two parallel sides of the base plate portion  17   b  above one surface of the base plate portion  17   b . When the connector  1  is mounted to a substrate  31 , such as a printed circuit board, the other surface of the base plate portion  17   b  is faced to the substrate  31 .  
         [0042]     Hereinafter, description will be made of an operation of manufacturing the connector  1  in this embodiment and mounting the connector  1  to the substrate  31 .  
         [0043]     Referring to  FIG. 1 , the contacts  11  are held on the base plate portion  17   b  of the insulator  17  with the predetermined space left from one another in the vertical and the horizontal directions. The first ground plates  13  arranged parallel to one another are positioned to be perpendicular to the second ground plates  15  arranged parallel to one another in the manner such that the first slits  13   s  are faced to the second slits  15   s . The first and the second ground plates  13  and  15  are press-fitted to each other in directions intersecting with each other by engaging the first and the second slits  13   s  and  15   s  to obtain the assembly in which the first and the second ground plates  13  and  15  are combined in the lattice fashion.  
         [0044]     When the first and the second slits  13   s  and  15   s  are combined with each other, the first and the second ground plates  13  and  15  are easily guided into the second and the first slits  15   s  and  13   s , respectively, by the first slant edges  13   p  formed on the first slit  13   s  at the portions adjacent to the first side  13   a  and the second slant edges  15   p  formed on the second slit  15   s  at the portions adjacent to the second side  15   a.    
         [0045]     When the first and the second ground plates  13  and  15  are combined with each other, the first contacting portions  13   z  are brought into press contact with the second plate surfaces  15   f . On the other hand, the second contacting portions  15   z  are brought into press contact with the first plate surfaces  13   f.    
         [0046]     Thereafter, the assembly is held on the insulator  17 . The insulator  17  is mounted to the substrate  31  and terminal portions (not shown) of the contacts  11  are connected to a signal circuit of the substrate  31 . At this time, the first ground terminal portions  13   u  illustrated in  FIG. 2  are connected to a ground circuit (not shown) formed on the substrate  31  ( FIG. 1 ) on which the connector  1  is mounted. The second ground terminal portions  15   u  are connected to the ground circuit formed on the substrate  31  ( FIG. 1 ) on which the connector  1  is mounted. Thus, the electrical connector is given a structure with a pseudo coaxial line.  
         [0047]     The first and the second slit portions  13   s  and  15   s  may be designed so that bottom surfaces  13   r  and  15   f  of the first and the second slit portions  13   s  and  15   s  are butted to each other when the first and the second ground plates  13  and  15  are combined. In this event, when the connector  1  is mounted to the substrate  31 , the first and the second ground terminal portions  13   u  and  15   u  can be press-fitted to through holes (not shown) of the substrate  31  by simply pressing the second ground plates  15  against the substrate  31 .  
         [0048]     Continuously referring to  FIG. 1 , a mating connector  51  to be coupled and connected to the connector  1  comprises a plurality of mating contacts (not shown), a mating insulator  55  holding the mating contacts, and a mating ground member (not shown) to be contacted with the ground member  12  comprising the first and the second ground plates  13  and  15 . The mating connector  51  is mounted to a mating substrate  61 , such as a printed circuit board.  
         [0049]     The contacts  11  are individually placed in the contact accommodating portions  21 , respectively. Therefore, by the first and the second ground plates  13  and  15  contacted with each other through the first and the second contacting portions  13   z  and  15   z , the contacts  11  are completely shielded from one another. With this structure, it is possible to prevent occurrence of crosstalk between the contacts  11  and deterioration in transmission characteristics.  
         [0050]     Referring to  FIG. 7 , a connector according to a second embodiment is similar to the connector in the first embodiment except that the first ground plate  13  has a first slit portion  13   s ′ different in structure from the first slit portion  13   s . Similar parts are designated by like reference numerals and description thereof will be omitted.  
         [0051]     As illustrated in  FIG. 7 , the first slit edges  13   y  of the first slit portion  13   s ′ are provided with a plurality of first additional slit portions  13   g  each of which is formed as a cut groove connected to the first slit  13   s ′. The first additional slit portions  13   g  extend from the first slit edges  13   y  along the first contacting portions  13   z  inward of the first contacting portions  13   z.    
         [0052]     Thus, the first contacting portions  13   z  in this embodiment form first contacting portions  14  of an arm-like curved shape by the presence of the first additional slit portions  13   g . When the first and the second ground plates  13  and  15  are combined with each other, the first contacting portions  14  are brought into elastic contact with the second plate surfaces  15   f  of the second ground plate  15 .  
         [0053]     In the second embodiment, the first additional slit portions  13   g  are formed in the first ground plate  13  to form the first contacting portions  14 . Alternatively or additionally, the second ground plate  15  may be provided with a plurality of additional slit portions similar to the first additional slit portions to form second contacting portions similar in shape to the first contacting portions  14 .  
         [0054]     In the first and the second embodiments, description has been directed to the case where the first and the second ground plates  13  and  15  have the first and the second contacting portions  13   z  and  15   z , respectively. Alternatively, only one of the first and the second ground plates  13  and  15  may be provided with the contacting portions.  
         [0055]     In the foregoing embodiments, a plurality of the first and the second contacting portions  13   z  and  15   z  are formed. Alternatively, each of the first and the second contacting portions  13   z  and  15   z  may be formed at only one position of each of the first and the second slit edges  13   y  and  15   y.    
         [0056]     The gap between the first slit edges  13   y  and the gap between the second slit edges  15   y  may be slightly greater than the thickness of the second ground plate  15  and the thickness of the first ground plate  13 , respectively.  
         [0057]     The first and the second ground plates  13  and  15  may be chamfered on a coupling side to be coupled to the mating connector  51 . In this event, the connector  1  is easily coupled to the mating connector  51 .  
         [0058]     As described above, in the above-mentioned electrical connector, the first and the second ground plates having the first and the second slit portions are combined into a lattice-like assembly in which the first and the second ground plates are contacted with each other. Therefore, the contacts are completely shielded from one another.  
         [0059]     The contacting portions are contacted with at least one plate surface of the first and the second ground plates. Therefore, it is possible to reduce occurrence of crosstalk between the contacts and to avoid deterioration in transmission characteristics.  
         [0060]     Since the first and the second plate surfaces are contacted through the contacting portions, the first and the second ground plates exhibits a stable shielding effect.  
         [0061]     In addition, the first and the second ground plates have a simple structure which can be formed by punching using a punch press without requiring a bending process. Thus, production is easy and the number of parts is reduced.  
         [0062]     The assembly of the first and the second ground plates can easily be assembled if the gap between the first slit edges and the gap between the second slit edges are greater than the thickness of the second ground plate and the thickness of the first ground plate, respectively.  
         [0063]     After the assembly is formed, the first or the second plate surface is pressed and contacted by the contacting portions so that no play or wobbling occurs.  
         [0064]     If the additional slit portions are formed so that the contacting portions have elasticity, the contacting portions are brought into elastic contact with the first or the second plate surfaces so that a stable contacting condition is achieved. This prevents the first and the second ground plates as thin metal plates from being deformed.  
         [0065]     When the connector is mounted to the substrate after the first and the second ground plates are combined with each other, the ground terminal portions can be press-fitted into the through holes formed in the substrate by merely pressing the first or the second ground plates. Therefore, a press-fit tool can be simplified.  
         [0066]     Although the present invention has been shown and described in conjunction with a few preferred embodiments thereof, it should be understood by those skilled in the art that the present invention is not limited to the foregoing description but may be changed and modified in various other manners without departing from the spirit and scope of the present invention as set forth in the appended claims.