Abstract:
An electrical connector includes an insulator and a plurality of contacts supported by the insulator. The insulator formed of an insulating plastic material is formed with a plurality of contact insertion apertures for inserting the contacts. Surfaces of the insulator around the contact insertion apertures are metallized, while the contact insertion apertures are independently electrically insulated. With this arrangement, substantially high shielding effect and sufficiently high speed information transmission are effectively accomplished.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    This invention relates to an electrical connector for use in electric and electronic appliances and more particularly to an electrical connector improved in shielding to deal with high-speed information transmission.  
           [0002]    [0002]FIG. 6 partly illustrates a hitherto used electrical connector viewed from a mating connector. Such an electrical connector of the prior art has a substantially rectangular parallelepiped configuration and includes mainly an insulator and contacts fixed thereto. These contacts may be divided into signal contacts (+S 1 ), phase inversion signal contacts (−S 1 ) with an inverted phase, and ground contacts (G). These contacts are arranged in a manner such that the signal contacts and the phase inversion signal contacts are in pairs and these pairs are surrounded by the ground contacts as shown in FIG. 6.  
           [0003]    The signal, phase inversion signal and ground contacts are arranged in the insulator in the manner described above in order to improve the shielding effect to deal with high-speed transmission. Even with fine or narrow pitches of contacts, however, gaps between the ground contacts become rather wider so that shielding effect could not be sufficiently obtained and hence information transmission speed would be objectionably limited to values of the order of several hundreds mega bits per second.  
         SUMMARY OF THE INVENTION  
         [0004]    It is an object of the invention to provide an improved electrical connector which eliminates all the disadvantages of the prior art and improves its shielding effect to deal with higher speed information transmission sufficiently.  
           [0005]    In order to accomplish the object of the invention, in an electrical connector including a plurality of contacts and an insulator holding the contacts, according to the first aspect of the invention the insulator formed of an insulating plastic material is formed with contact insertion apertures for inserting the contacts, surfaces of the insulator around the contact insertion apertures being metallized and the contact insertion apertures being independently electrically insulated. With the metallized surfaces around the contact insertion apertures in this manner, gaps between shielding layers become narrower.  
           [0006]    In another aspect of the invention, the insulator formed of an insulating plastic material is formed with pairs of contact insertion apertures for inserting the contacts, surfaces of the insulator around the pairs of contact insertion apertures being metallized and the pairs of contact insertion apertures being independently electrically insulated.  
           [0007]    In a preferred embodiment of the invention, the contact insertion apertures are metallized apertures.  
           [0008]    In a further aspect of the invention, the insulator formed of an insulating plastic material is formed with a plurality of contact insertion apertures for inserting the contacts, surfaces of the insulator around the contact insertion apertures and some of the contact insertion apertures being metallized and required number of the contact insertion apertures being independently electrically insulated.  
           [0009]    Preferably, the insulator comprises a main body substantially in the form of a flat plate and a plurality of projections extending from the main body, and the projections and the main body are formed with a plurality of contact insertion apertures passing therethrough, the main body being entirely metallized and a required number of the contact insertion apertures being independently electrically insulated.  
           [0010]    The term “metallizing” used herein means a treatment for coating an insulator with a metallic film to make electrically conductive the surface of the insulator.  
           [0011]    The electrical connector having the subject features of the invention can bring about the following significant effects.  
           [0012]    (1) According to the invention, since the surfaces around the contact insertion apertures for inserting the contacts are metallized, the effective shielding is obtained with great certainty to make possible higher information transmission speed.  
           [0013]    (2) According to the invention, since the surfaces around a pair of contact insertion apertures for inserting the signal contact and the phase inversion signal contact are metallized, the effective shielding is obtained very reliably to deal with high-speed information transmission higher than several thousands mega bits per second.  
           [0014]    (3) According to the invention, ground contacts can be easily grounded or earthed by merely inserting the ground contacts into the contact insertion apertures.  
           [0015]    (4) According to the invention, when the contacts are pairs of signal contacts and ground contacts, the grand contacts are inserted into the contact insertion apertures so as to be grounded according to designated specifications of the connector to meet the requirements of the specifications with ease.  
           [0016]    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  
       [0017]    [0017]FIG. 1A is a perspective view of an electrical connector according to one aspect of the invention;  
         [0018]    [0018]FIG. 1B is a sectional view of the electrical connector taken along a plane A-A in FIG. 1A;  
         [0019]    [0019]FIG. 2 is a sectional view of an electrical connector according to another aspect of the invention including metallized projections each having a pair of contact insertion apertures;  
         [0020]    [0020]FIG. 3 is a sectional view of an electrical connector according to an embodiment of the invention illustrating metallized inner surfaces of contact insertion apertures;  
         [0021]    [0021]FIG. 4 is a sectional view of an electrical connector according to a further aspect of the invention including metallized projections each having three contact insertion apertures;  
         [0022]    [0022]FIG. 5 is a sectional view of an electrical connector according to another embodiment of the invention whose main body of an insulator is metallized as a whole; and  
         [0023]    [0023]FIG. 6 illustrates an electrical connector of the prior art viewed from the side of a mating connector.  
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0024]    [0024]FIG. 1A illustrates in a perspective view an electrical connector according to the first aspect of the invention whose cross-section is shown in FIG. 1B taken along a plane A-A in FIG. 1A. FIG. 2 illustrates, in a sectional view, metallized projections of the electrical connector each having a pair of contact insertion apertures. FIG. 3 shows contact insertion apertures with metallized inner surfaces. FIG. 4 illustrates metallized projections each having three contact insertion apertures. FIG. 5 shows a cross-section of an electrical connector illustrating a main body and a plurality of metallized projections extending therefrom.  
         [0025]    The electrical connector  10  according to the invention shown in FIG. 1A comprises a plurality of contacts and an insulator  12 . The contacts are divided into signal contacts  14  and phase inversion signal contacts  16 .  
         [0026]    The insulator  12  is injection molded from an electrically insulating plastic material in the conventional manner. Preferred materials from which to form the insulator  12  include polybutylene terephthalate (PBT), liquid crystal polymer (LCP), polyphenylene sulfide (PPS), polyamide (46PA or 66PA) and the like in view of the requirements imposed on such an insulator with respect to moldability and dimensional stability.  
         [0027]    The contacts are made of a metal and formed by the press-working in the conventional manner. Preferred metals for the contacts are brass, phosphor bronze, beryllium copper and the like in consideration of good electrical conductivity, springiness and the like.  
         [0028]    As shown in FIG. 1A, the electrical connector of the first aspect of the invention corresponding to claim 1 comprises the insulator  12  and a plurality of contacts fixed to the insulator by press-fitting, hooking or any other anchoring means. Each of the contacts mainly consists of a contact portion  24  adapted to contact a mating contact, a fixed portion  26  to be fixed to the insulator  12 , and a connection portion  28  to be connected to a circuit board or substrate and extending from the insulator  12  when assembled therein. While the contacts of straight dip type are shown in the illustrated embodiment, it will be apparent that contacts of other types such as surface mounting type (SMT) and L-shaped dip type may be used.  
         [0029]    The insulator  12  comprises a main body  34  and projections  36  having contact insertion apertures  22  passing therethrough, and surfaces of the insulator around the contact insertion apertures  22  are metallized as shown by reference numerals  20 . The term of “surfaces around the contact insertion apertures” used herein includes the upper surface  30  of the main body  34  and all side surfaces  31  of the projections  36 . In this manner, the insulator  12  is partially metallized as shown by numerals  20 , while the contact insertion apertures  22  themselves are independently or separately electrically insulated from the metallized portions and the contacts.  
         [0030]    Such an arrangement of the metallized portions according to the invention makes it possible to be compatible two opposed states, that is, the conductivity by metallizing the insulator  12  and the independent insulation of the contact insertion apertures  22 . In the illustrated embodiment, there are provided on the main body  34  of the insulator  12  a plurality of the externally metallized projections  36  in each of which one contact is arranged.  
         [0031]    The contact insertion apertures  22  may be straight apertures extending through the insulator  12 . Preferably, however, the contact insertion aperture includes an guide portion  38  with inclined faces on the side of a mating contact for assisting its fitting and a guiding aperture  40  with a smaller diameter than that of the contact insertion aperture  22  for guiding the mating contact.  
         [0032]    A method for metallizing the insulator  12  will be explained hereinafter. The metallized surfaces  20  of the insulator  12  are surfaces coated with metallic films making the surfaces electrically conductive as described above. As the insulator  12  is made of an insulating material, its surfaces are metallized by treating with electroless plating, vapor deposition or the like to make the surfaces electrically conductive. Preferred materials to be used for the metallization include copper (Cu), nickel (Ni) and the like in consideration of the shielding effect, electrical conductivity and the like.  
         [0033]    In order to independently electrically insulate the contact insertion apertures  22  from the metallized portions of the insulator, first the insulator  12  may be metallized as a whole with the exception of the contact insertion apertures. Thereafter, removed are the metallized surfaces on the side to be fitted with mating contacts and the metallized surfaces of the insulator which are peripheries of the contact insertion apertures from which the connection portions of the contacts extend outwardly, by the use of a removing method such as mechanical working by an end mill or grinding, blasting treatment, chemical etching or the like. As an alternative, such surfaces of the insulator not requiring the metallization are previously covered by masking before metallization in order to prevent from being metallized.  
         [0034]    [0034]FIG. 2 illustrates an electrical connector  10  according to another aspect of the invention corresponding to claim 2. Only features of the connector shown in FIG. 2 different from those shown in FIGS. 1A and 1B will be explained. The electrical connector  10  shown in FIG. 2 comprises an insulator  12  including projections  36  each having a pair or two of contacts, one being a signal contact  14  and the other a phase inversion signal contact  16  which are fixed to the insulator  12 . Each of the projections  36  includes a pair of contact insertion apertures into which the signal contact  14  and phase inversion signal contact  16  are inserted, respectively.  
         [0035]    The metallization is also performed on the surfaces around pairs of the contact insertion apertures  22 . The exact meaning of “surfaces of the insulator around . . . ” is as defined above. Therefore, the insulator  12  is partly metallized, or metallized surfaces are partly removed to obtain independently electrically insulated contact insertion apertures in pairs. In this embodiment a plurality of the metallized projections  36  are also arranged on the main body  34  of the insulator  12 . The procedure for metallizing the insulator and obtaining the independently insulated contact insertion apertures is substantially similar to that in the first aspect of the invention shown in FIG. 1A.  
         [0036]    [0036]FIG. 3 illustrates an electrical connector  10  according to one embodiment of the invention corresponding to claim 3. In this embodiment, when the insulator  12  is metallized as a whole, the inner surfaces of the contact insertion apertures  22  or pairs of the apertures  22  are metallized at a time as shown in FIG. 3 and then the metallized inner surfaces of the apertures  22  may be removed together with other needless metallized surface portions. As a result, the contact insertion apertures  22  or pairs of contact insertion apertures  22  are independently electrically insulated. In other words, the inner surfaces of the contact insertion apertures  22  or pairs of the apertures  22  are once metallized besides the surfaces around the contact insertion apertures  22  or pairs of contact insertion apertures  22 , and then the metallized inner surfaces of the contact insertion apertures  22  or pairs of apertures  22  are removed. The procedure for metallizing the insulator and obtaining the independently insulated contact insertion apertures is substantially similar to that described above.  
         [0037]    [0037]FIG. 4 illustrates an electrical connector  10  according to a further aspect of the invention corresponding to claim 4. The electrical connector  10  comprises an insulator  12  and projections  36  each having three contacts therein. The three contacts are divided into two signal contacts  14  and a ground contact  18 , all the contacts being fixed to the insulator  12 . The insulator  12  includes the projections  36  each having three contact insertion apertures  22  for inserting three contacts.  
         [0038]    In this case, surfaces around the three contact insertion apertures  22  of each of the projections  36  and their inner surfaces of the contact insertion apertures  22  at each of the projections  36  are once metallized. The metallized surfaces  20  are surfaces around the three contact insertion apertures  22  (the same as in the first aspect of the invention corresponding to claim 1) and the inner surfaces of the three contact insertion apertures  22  at each of the projections. All the three contact insertion apertures  22  are once metallized, but among them the two contact insertion apertures  22  for the signal contacts are independently electrically insulated.  
         [0039]    In more detail, the two contact insertion apertures  22  for the signal contacts  14  are independently electrically insulated, while the remaining one contact insertion aperture  22  for the ground contact remains metallized so as to be electrically connected through the metallization to the frame ground thereabout. Although the three contacts in one projection are shown in the embodiment, it is to be understood that any numbers of contacts in one projection may be arranged according to designated specifications and cables. The numbers of contact insertion apertures to be independently electrically insulated may also be suitably determined according to specifications designated for connectors. The procedure for metallizing the insulator and obtaining the independently insulated contact insertion apertures is substantially similar to that described above.  
         [0040]    [0040]FIG. 5 illustrates an electrical connector  10  according to a further embodiment of the invention substantially similar to the connector shown in FIG. 2 with respect to the arrangement of the insulator  12  and the contacts. In the illustrated embodiment, in addition to the metallized surfaces  20  of the electrical connector  10  shown in FIG. 2, the substantially flat surface of the main body  34  of the insulator  12  is entirely metallized as shown in FIG. 5. Depending upon designated specifications, the metallized surfaces are partly removed to make the contact insertion apertures independently electrically insulated. The procedure for metallizing the insulator and obtaining the independently insulated contact insertion apertures is substantially similar to that described above.  
         [0041]    In accordance with designated specifications, the main body  34  of an insulator  12  is formed with apertures which are metallized and then into which pins are simply inserted, whereby desired grounding or earthing is accomplished with ease.  
         [0042]    While the invention has been particularly shown and described with reference to 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.