Abstract:
An electrical connector includes a pin connector and a socket connector. The pin connector has a plurality of pin contacts, a required number of grand contacts and a block for holding the pin and ground contacts. The socket connector has a plurality of socket contacts, a required number of ground contacts and a housing for holding the socket and ground contacts. The block and housing are each formed from an insulating plastic material and formed with contact insertion apertures into which the contacts are inserted and fixed. Further, the block and housing each have metallized surfaces around the contact insertion apertures in a manner to electrically insulate these contact insertion apertures for pin and socket contacts independently from one another. The electrical connector thus constructed is easily and economically manufactured while being capable of achieving sufficient shielding effect leading to sufficiently high speed transmission.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to an electrical connector for use in electric or electronic appliances, and more particularly to an electrical connector with signal contacts and ground contacts improved in arrangement and construction for use in high speed transmission. 
     There is disclosed in Japanese Patent Application Opened No. 2000-507,740 an electrical connector assembly including an insulating housing, a plurality of terminal modules incorporated therein and conductive shields therebetween. Each of the terminal modules includes a plurality of contacts each of which consists of a fitting contact portion, a conductor connection portion and an intermediate portion therebetween, the intermediate portion being completely or partly enclosed and held in an insulating web. Each of the modules has a conductive shield attached thereto. 
     With this connector assembly, each shield at least includes a first elastic arm adapted to be brought into electrical contact with one contact selected from contacts in the terminal module to which the shield is secured, and a second elastic arm outwardly extending from the adjacent terminal module and adapted to be brought into electrical contact with one contact selected from contacts in the adjacent terminal module. 
     For the purpose of providing an electrical connector with ground contacts to be easily manufactured, disclosed in Japanese Patent Application Opened No. 2002-50,436 is a connector having a plurality of signal contacts arranged in a predetermined plane and ground contacts arranged between the signal contacts, these contacts being held in an insulator. The insulator is provided on its specific surface with a ground plate secured thereto and is formed with windows through which parts of the ground contacts and parts of the signalcontacts adjacent thereto are exposed, the ground plate having contact portions adapted to contact the ground contacts through the windows. 
     These known connectors disclosed in the two patent literatures are intended to adapt to the high speed transmission and have an object to reduce the cross talk between signals passing through a plurality of signal contacts. 
     Moreover, a prior art proposal has attempted to reduce the cross talk by arranging contacts in a particular arrangement as shown in FIG.  5 . In more detail, signal contacts (+S 1 , +S 2 , +S 3  . . . ), phase inversion signal contacts (−S 1 , −S 2 , −S 3  . . . ), and ground contacts (G) are arranged in a manner that ground contacts (G) surround a pair of contacts +S 1  and −S 1 , a pair of contacts +S 2  and −S 2 , a pair of contacts +S 3  and −S 3 , . . . As can be seen from  FIG. 5 , it may be recognized in this arrangement that the ground contacts are arranged between pairs of contacts, each pair consisting of a signal contact and a phase inversion signal contact. 
     The connectors disclosed in the above patent literatures and the prior art proposal are beneficial to some extent for obtaining high shielding effect and high speed transmission. 
     With the case of arranging ground contacts between pairs of signal contact and phase inversion signal contact, if a pitch between the contacts is very narrow, clearances between the ground contacts would unavoidably become large. In the connectors disclosed in the Japanese Patent Application Opened Nos. 2000-507,740 and 2002-50,436, it is also unavoidable to enlarge clearances between the shielded signal contacts to some extent, so that sufficient shielding effect could not be obtained. As a result, the transmission speed would be limited to the order of several hundreds Mbps, which would not fully comply with imposed requirement of even higher speed transmission in future. Whereas efforts to date have been beneficial, technical problems remain to be solved. 
     With the connectors disclosed in the patent literatures described above, the number of parts inevitably increases so that the cost would go up concerning their management and fabrication. 
     SUMMARY OF THE INVENTION 
     In view of the above problems with the prior art, it is an object of the invention to provide an electrical connector which is easily and economically manufactured and capable of achieving sufficient shielding effect to fulfill the requirement of higher speed transmission. 
     In order to accomplish the above object, in an electrical connector comprising a pin connector and a socket connector, the pin connector including a plurality of pin contacts, a required number of grand contacts and a block for holding the pin and ground contacts, and the socket connector including a plurality of socket contacts, a required number of ground contacts and a housing for holding the socket and ground contacts, according to the invention the block and housing are each formed from an insulating plastic material and formed with contact insertion apertures into which the contacts are inserted, and the block and housing each have metallized surfaces around the contact insertion apertures in a manner to electrically insulate these insertion apertures for pin and socket contacts independently from one another. 
     By metallizing the surfaces around the contact insertion apertures, clearances between the shield layers can be reduced. 
     In a preferred embodiment, the block of the pin connector is formed with grooves on either, or both, of the fitting side of the block and the connecting side to a board to make independent the pin contacts from one another, while the block is provided with at least one groove around the ground contacts and with at least one further groove to communicate the at least one groove with the contact insertion apertures for the ground contacts. Moreover, the housing of the socket connector is formed with grooves on the fitting side of the housing to make independent the socket contacts from one another, while the housing is provided with at least one groove around the ground contacts. 
     Preferably, the block of the pin connector is metallized on its surfaces around the contact insertion apertures for the pin contacts, while the ground contacts are each arranged between the pin contacts in columns or rows. Further, the housing of the socket connector is metallized on its surfaces around the contact insertion apertures for the socket contacts, while the ground contacts of the socket connector are arranged in positions corresponding to those of the ground contacts of the pin connector. 
     In another embodiment, the pin contacts of the pin connector form respective pairs of pin contacts, each consisting of the two pin contacts, and the block of the pin connector is formed with grooves on either, or both, of the fitting side of the block and the connecting side of a board to make independent the pairs of pin contacts from one another, while the block is provided with at least one groove around the ground contacts and with at least one further groove to communicate the at least one groove with the contact insertion apertures for the ground contacts. Moreover, the socket contacts of the socket connector form respective pairs of socket contacts, each consisting of the two socket contacts, and the housing of the socket connector is formed with grooves on the fitting side of the housing to make independent the pairs of socket contacts from one another, while the housing is provided with at least one groove around the ground contacts. 
     Preferably, the block of the pin connector is metallized on its surfaces around pairs of the contact insertion apertures for the pin contacts, while the ground contacts are each arranged between two pairs of pin contacts in columns and rows. Moreover, the housing of the socket connector is metallized on its surfaces around pairs of the contact insertion apertures for the socket contacts, while the ground contacts of the socket connector are arranged in positions corresponding to those of the ground contacts of the pin connector. 
     In a further embodiment, the pin contacts of the pin connector form respective sets of pin contacts, each consisting of a plurality of the pin contacts, and the block of the pin connector is formed with grooves on either, or both, of the fitting side of the block and the connecting side to a board to make independent the sets of the pin contacts from one another, while the block is provided with at least one groove around the ground contacts and with at least one further groove to communicate the at least one groove with the contact insertion apertures for the ground contacts. Further, the socket contacts of the socket connector form respective sets of the socket contacts, each consisting of a plurality of the socket contacts, and the housing of the socket connector is formed with grooves on the fitting side of the housing to make independent the sets of the socket contacts from one another, while the housing is provided with at least one groove around the ground contacts. 
     Preferably, the block of the pin connector is metallized on its surfaces around sets of the contact insertion apertures for the pairs of pin contacts, while the ground contacts are each arranged between two sets of the pin contacts in columns and rows. Moreover, the housing of the socket connector is metallized on its surfaces around sets of the contact insertion apertures for the sets of socket contacts, while the ground contacts of the socket connector are arranged in positions corresponding to those of the ground contacts of the pin connector. 
     According to the invention, the housing of the socket connector comprises a main portion in the form of a substantially flat plate, and a plurality of projections extending from the main portion, the contact insertion apertures passing through the main portion and the projections, and the main portion and the projections are metallized on their substantially entire surfaces so as to allow the contact insertion apertures for the socket contacts to be electrically insulated independently from one another. 
     In an embodiment of the invention, the contact insertion apertures for the ground contacts only are metallized. 
     The metallization is here understood as signifying the condition of an insulator coated on its surface with a metal film so as to be electrically conductive. 
     The electrical connector thus constructed according to the invention can bring about the following significant effects.
     (1) The metallization around the contact insertion apertures for the pin, socket and ground contacts according to the invention ensures the shielding effect to reduce the cross talk, thereby enabling the high speed transmission.   (2) According to the invention the pin contacts of the pin connector and the socket contacts of the socket connector form pairs of contacts, respectively, each pair consisting of a signal contact and a phase inversion signal contact, and the surfaces of the insulators around the contact insertion apertures for the pin and socket contacts are metallized. With such a construction, the shielding is securely effected to achieve higher speed transmission of more than several thousands Mbps.   (3) According to the invention, the block of the pin connector is formed with grooves on either, or both, of the fitting side of the block and the connecting side to a board to make the pin contacts independent from one another, while the block is provided with at least one groove around the ground contacts and with at least one further groove to communicate the at least one groove with the contact insertion apertures for the ground contacts. Further, the housing of the socket connector is formed with grooves on the fitting side of the housing to make the contact insertion apertures for the socket contacts independent from one another, while the housing is provided with at least one groove around the contact insertion apertures for the ground contacts. With this construction, the surfaces around the contact insertion apertures for the pin, socket and ground contacts are metallized to achieve the shielding effect with great certainty, thereby reducing the cross talk and realizing the higher speed transmission.   (4) According to the invention, the block of the pin connector is formed with the at least one further groove communicating the at least one groove with the contact insertion apertures for the ground contacts, thereby easily permitting the earthing of the ground contacts.   (5) According to the invention, by mere insertion of the ground contacts into the contact insertion apertures of the pin and socket connectors, the ground contacts can be readily earthed.   (6) The electrical connector according to the invention can be easily used as a signal transmission electrical connector having signal contacts and ground contacts in pairs by earthing the ground contacts in accordance with specifications of connectors.   

     The invention will be more fully understood by referring to the following detailed specification and claims taken in connection with the appended drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view illustrating a pin connector and a socket connector of an electrical connector according to the invention; 
         FIG. 2  is a perspective view illustrating the block and housing of the pin and socket connectors shown in  FIG. 1 ; 
         FIG. 3A  is a sectional view of the block shown in  FIG. 2  taken along a plane including the contact insertion apertures in a column; 
         FIG. 3B  is a sectional view of the block shown in  FIG. 2  taken along a plane including the contact insertion apertures in a row; 
         FIG. 4A  is a sectional view of the housing shown in  FIG. 2  taken along a plane including the contact insertion apertures in a column; 
         FIG. 4B  is a sectional view of the housing shown in  FIG. 2  taken along a plane including the contact insertion apertures in a row; and 
         FIG. 5  illustrates one exemplary arrangement of signal contacts and ground contacts of the prior art. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     An electrical connector  1  according to the present invention comprises a pin connector  10  and a socket connector  30  as shown in FIG.  1 . The pin connector  10  comprises an insulator or block  12  made of an insulating plastic material and pin contacts  14  and ground contacts  18  made of a metal. In a similar manner, the socket connector  30  comprises an insulator or housing  32  made of an insulating plastic material and socket contacts  34  and ground contacts  38  made of a metal. 
     These insulators are injection molded from an insulating plastic material. Preferred plastics from which to form these insulators include, but not limited to, polybutylene terephthalate (PBT), liquid crystal polymer (LCP), polyphenylene sulfide (PPS), polyamide (46PA or 66PA) and the like in view of the requirements imposed on the block and housing with respect to workability, dimensional stability and the like. The contacts are formed of a metal by the press-working in the conventional manner. Preferred metals for the contacts may include but not limited to brass, phosphor bronze, beryllium copper and the like with a view to obtaining the conductivity and springiness. 
       FIG. 1  illustrates in a perspective view the electrical connector  1  comprising the pin connector  10  and the socket connector  30  whose respective block  12  and housing  32  are shown in FIG.  2 .  FIGS. 3A and 3B  are cross-sectional views of the block  12  taken along planes passing through centers of contact insertion apertures in column and row, respectively.  FIGS. 4A and 4B  are cross-sectional views of the housing  32  taken along planes passing through centers of contact insertion apertures in column and row, respectively. 
     Respective components of the pin connector  10  and the socket connector  30  will be explained, particularly with their constructions, herebelow. 
     The pin connector  10  comprises a block  12  and pin contacts  14  and ground contacts  18 . The block  12  is substantially U-shaped as shown in FIG.  3 A and is formed with a plurality of contact insertion apertures  16  for holding and fixing the respective pin and ground contacts  14  and  18 . The surfaces of the block  12  are metallized around the bottom portion provided with the contact insertion apertures  16 . The metalized surfaces layers are denoted by reference numeral  20 . The layers  20  of metallization are shown in  FIGS. 3A ,  3 B,  4 A and  4 B, whose thickness is on an exaggerated scale. The block  12  is formed with slit shape grooves  22  on either one, or both, of the fitting side of the block  12  and the connecting side to a board to make the pin contacts independent from one another. 
     The “fitting side of the block” used herein means that side of the block  12  on which the housing  32  of the socket connector  30  is fitted in the space  26  defined by the U-shaped block  12  of the pin connector  10 . On the other hand, the “connecting side to a board” used herein means the opposite side of the “fitting side of the block”, that is, the side on which the pin contacts are connected to a board. 
     The block  12  is further formed about the ground contacts with at least one groove  22  and with at least one further groove portion  24  for communicating the slit shape groove  22  around the ground contacts with the contact insertion aperture  16  for the ground contacts  18 . Whereas the grooves  22  may be provided on both the sides of the ground contacts  18  as shown in  FIG. 1 , the grooves  22  may be provided in column and rows to surround the respective ground contacts  18 . Employing such grooves  22  and groove portion  24  can allow metallization on these portions, by means of which shielding effect is provided to reduce the cross talk and to realize the high speed transmission. 
     Further, the groove portions  24  are beneficial for earthing of the ground contacts  18 . The groove portion  24  may be only one and may extend parallel with or vertically to the two grooves  22  on both the sides of the ground contacts  18  or may be “cross-shaped” or X-shaped. The more the number of the groove portions  24 , the better is the result of earthing of the ground contacts  18 . 
     The depths of the grooves  22  and groove portions  24  may be suitably determined in consideration of the strength of the block  12  and the purposes of these grooves. The cross-sectional shape of the contact insertion aperture  16  may be rectangular as shown, but may be circular if it is for a single contact. The cross-sectional shape may be elliptical for more than one contact. 
     Aside from the procedure of the metallization which will be explained later, the contact insertion apertures  16  for respectively inserting the pin contacts  14  are electrically insulated independently from one another. In other words, the block  12  including grooves  22  and groove portions  24  is metallized in its entirety with exception of the fitting surfaces of the contact insertion apertures  16  to contact the pin contacts  14  and the surface on the side of tail portions or connection portions of the pin contacts  14 . 
     The pin contacts  14  and the ground contacts  18  are fixed in the contact insertion apertures  16  by press-fitting, hooking or lancing or the like. The pin contact  14  consists mainly of a contact portion to contact a mating contact, a fixed portion to be fixed to the block  12  and a connection portion to be connected to a board or substrate. The connection portion extending from the block  12  may be of the straight dip type, surface mounting type (SMT), or L-shaped dip type. 
     In the shown embodiment, two pin contacts  14  arranged in one column form a pair of contacts (consisting of one signal contact and one phase inversion signal contact) and each ground contact  18  is arranged between two pairs of pin contacts  14 . In other words, there are five contact insertion apertures  16  in each one column, and the contacts are arranged therein, in that order, two pin contacts  14 , one ground contact  18 , and two pin contacts  14  in the shown embodiment. Three pin contacts  14  may from one set of contacts and one ground contact  18  may be arranged between two sets of pin contacts  14 , or one ground contact  18  may be two pin contacts  14  in accordance with a specification of the relevant connector. Although the five rows of the contacts are shown in  FIGS. 1 and 2 , it is to be understood that eight rows of the contacts may be used. 
     While each ground contact  18  is arranged between two pairs of pin contacts  14  in columns in the shown embodiment, it will be apparent that such an arrangement of the pin and ground contacts may be employed in rows. Similarly to the column, each the ground contact may be arranged between two pairs of pin contacts in the row or between two sets of pin contacts, each set consisting of three pin contacts in the row. 
     The socket connector  30  comprises a housing  32 , and socket contacts  34  and ground contacts  38 . The housing  32  is substantially in the form of a square block having two ridges each one side of its one end as shown in  FIGS. 2 and 4A . The housing  32  is formed with contact insertion apertures  36  for inserting and fixing therein socket contacts  34  and ground contacts  38 . The housing  32  is further formed on its fitting side with groove portions  42  to make independent the contact insertion apertures  36  for the socket contacts  34  from one another and is further formed with at least one slit shape groove portion  42  around the contact insertion apertures  36  for the ground contacts  38 . A plurality of groove portions  42  may be provided on both the sides of the ground contacts  38  as shown in  FIG. 1  or may be provide so as to surround the respective ground contacts  38 . 
     After providing these groove portions  42 , the groove portions  42  are metallized around the contact insertion apertures  36  as shown by numerals  40  to provide shielding effect, thereby reducing the cross talk and achieving the high speed transmission. The depth of the groove portions  42  is suitably determined in consideration of the strength of the housing  32  and the purpose of the groove portions  42 . The housing  32  of the socket connector  30  comprises a main portion  48  in the form of a substantially flat plate and a plurality of projections  50  divided by the groove portions  42  and extending from the main portion  48 . The contact insertion apertures  36  pass through the projections  50  and the main portion  48 . 
     With the shown embodiment, the housing  32  is metallized on its main portion  48  and the projections  50  shown by reference numerals  40  with exception of the fitting surfaces of the contact insertion apertures  36  to contact the socket contacts  34  and the surface on the side of tail portions or connection portions of the socket contacts, thereby electrically insulating the respective contacts independently from one another. In this embodiment, as shown in  FIGS. 1 and 2  there are five contact insertion apertures in one column, and two contact insertion apertures  36  for the socket contacts  34  form one pair of apertures for the socket contacts  34  and one contact insertion aperture  36  for one ground contact  38  is arranged between two pairs of apertures  36  for the socket contacts  34 . 
     The cross-sectional shape of the contact insertion aperture  36  may be rectangular as shown, but may be circular if it is for a single contact. The cross-sectional shape may be elliptical for more than one contact. Preferably, the contact insertion aperture  36  is provided at its insertion end with a frustoconical guide  52  for the contact to be inserted thereinto as shown in FIG.  4 A. The end of the frustoconical guide  52  contiguous to the contact insertion aperture  36  preferably has a diameter just as large as or slightly smaller than that of the contact insertion aperture  36  for its purpose. 
     The socket contacts  34  and the ground contacts  38  are fixed in the contact insertion apertures  36  in the housing  32  by press-fitting, hooking or lancing or the like. The socket contact  34  consists mainly of a contact portion to contact a mating contact, a fixed portion to be fixed to the housing  32  and a connection portion to be connected to a board or substrate. The connection portion extends from the housing  32  and may be of the straight dip type, surface mounting type (SMT), or L-shaped dip type. Required numbers of the socket contacts  34  and the ground contacts  38  are embedded in an insulator by integrally molding them to form an integral contact assembly  56  as shown in  FIG. 1  which is adapted to be fitted and fixed in an engaging bore  58  formed in the housing  32  as shown in FIG.  4 A. 
     In the shown embodiment, two socket contacts  34  arranged in one column form a pair of contacts (signal contact and phase inversion signal contact) and each ground contact  38  is arranged between two pairs of socket contacts  34 . In other words, there are five contact insertion apertures  36  in each one column, and the contacts are arranged therein, in that order, two socket contacts  34 , one grand contact  38  and two socket contacts  34  as shown in  FIGS. 1 and 2 . As an alternative, three socket contacts  34  may form one set of contacts and one ground contact  38  may be arranged between two sets of socket contacts  34 , or one ground contact  38  may be arranged between two socket contacts  34  in accordance with a specification of the relevant connector. Other than the case of the five rows of the contacts shown in  FIG. 1 , eight rows of the contacts may also be employed. 
     In the illustrated embodiment, each ground contact  38  is arranged between two pairs of the socket contacts  34  in columns as described above. However, such an arrangement of the socket and ground contacts may be employed in rows. Namely, each the ground contact may be arranged between two socket contacts  34  in one row or between two sets of socket contacts  34  in one row. One set of socket contacts  34  may consist of more than two socket contacts  34 . 
     Among the contact insertion apertures of the pin and socket connectors  10  and  30 , the contact insertion apertures  16  and  36  for the ground contacts  18  and  38  only may be metallized on their inner surfaces. As described above, the surfaces of the block and housing are metallized “around” the contact insertion apertures. Namely, the block  12  of the pin connector  10  and the housing  32  of the socket connector  30  are metallized on their surfaces with exception of the fitting surfaces of the contact insertion apertures  16  and  36  for the pin and socket contacts  14  and  34  and the surfaces of the block  12  and housing  32  on the side of the tail portions or connection portions of the contacts. The metallization in this manner not only contributes to the electric conductivity of the block  12  and the housing  32  but also permits the contact insertion apertures  16  and  36  for the pin and socket contacts  14  and  34  to be electrically insulated independently from one another. 
     The procedure for metallizing the block  12  and the housing  32  will be explained hereinafter. As described above, the metallization is understood as signifying the condition of an insulator coated on its surface with a metal film so as to be electrically conductive. In order to carry out the metallizing, the insulator may be surface treated to make electrically conductive as by electroless plating or vapor deposition (vacuum evaporation). Preferred metals for the metallization include copper, nickel and the like in consideration of the shield effect and conductivity. 
     In order to electrically insulate the contact insertion apertures  16  and  36  for the pin and socket contacts  14  and  34  independently from one another, after the whole insulators (block  12  and housing  32 ) have been metallized, the metallized surfaces of fitting portions of the contact insertion apertures and of the insulators on the side of tail ends or connection portions of the contacts are treated to remove their metallized layers by working by means of end mills or grinder or treating by means of blasting or chemical etching. As an alternative, preparatory to the metallization, masking is used on such surface portions which are undesirable to be metallized. In the illustrated embodiment, the masking is employed for reasons of economy and performance. 
     While the invention has been particularly shown and described with reference to the preferred embodiments thereof, it will be understood by those skilled in the art that the foregoing and other changes in form and details can be made therein without departing from the spirit and scope of the invention.