Abstract:
A multi-coaxial connector comprises a metallic die-cast block having a plurality of through-holes, a plurality of L-shaped contacts each having foot and leg portions, and a plurality of insulator sleeves. The through-holes hold the foot portions of the L-shaped contacts on the inside circumferences thereof, via the insulator sleeves, respectively. The L-shaped contacts serve as inner coaxial conductors, while the metallic block serves as a common outer coaxial conductor for the inner coaxial conductors. The connector further comprises an insulator housing which has an open rear end and additional through-holes corresponding to the through-holes. Such insulator housing accommodates the front end of the metallic block inserted thereinto through the open end, so as to serve as a cap of the metallic block.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to a multi-coaxial connector for electrically connecting a plurality of coaxial cables to a connecting object such as a printed circuit board, and, in particular, to such a multi-coaxial connector which is fixed on and connected to the connecting object and which is removably coupled with a mating connector fixedly connected to a plurality of coaxial cables. 
     A coaxial cable is known in the prior art and is advantageously used for transmitting a high frequency signal. The coaxial cable comprises an inner conductor, an outer conductor surrounding the inner conductor through an insulator layer, and an outer jacket on the outer conductor. The inner conductor is used for transmitting electrical signal and the outer conductor serves for electromagnetically shielding the inner conductor. Thus, the use of the coaxial cable can avoid electromagnetic interference such as invading noise into the inner conductor from the outside and undesired radiation from the inner conductor due to the high-frequency signal flowing therethrough. 
     A coaxial connector is also known in the prior art for electrically connecting a coaxial cable with another coaxial cable. The coaxial connector comprises a plug unit and a receptacle unit which mutually mate. Each of the plug unit and the receptacle unit includes an inner contact element and an outer contact element connected to the inner conductor and the outer conductor, respectively, of the corresponding one of the both coaxial cables. 
     In order to connecting a plurality of coaxial cables with a connecting object such as a printed circuit board, a multi-coaxial connector is known in the prior art. The conventional connector includes a plurality of inner and outer contact pairs. Each of the inner and outer contact pairs comprises an inner contact element and an outer contact element surrounding, and insulated from, the inner contact element. Each of the inner and outer contact elements has a terminal portion which is fixed and connected, or soldered to a corresponding conductor, for example, a pad on the printed circuit board. A mating connector to be coupled with this multi-coaxial connector also includes a plurality of inner and outer contact pairs which are fixedly and electrically connected with inner and outer conductor pairs of the plurality of coaxial cables, respectively. 
     The conventional connector is mounted on the printed circuit board and the mating connector is connected and fixed to the plurality of coaxial cables. Then, the mating connector is coupled to the conventional connector, so that the plurality of coaxial cables are electrically connected to the printed circuit board. 
     As example of such conventional multi-coaxial connector is disclosed in U.S. Pat. No. Re. 36,065. 
     However, the conventional connector is composed of many parts, and requires a complicate manufacturing process, owing to the structure and the number of the parts. 
     SUMMARY OF THE INVENTION 
     This invention therefore provides the multi-coaxial connector which consists of less parts and can be readily manufactured, in comparison with the conventional connector. 
     According to one aspect of the present invention, a multi-coaxial connector comprises a metallic block, a plurality of contact elements, and a plurality of insulator sleeves. 
     The metallic block has a front end surface and a rear end surface, and is formed with a plurality of first through-holes extending in parallel with each other between the front end and the rear end of the metallic block. Such metallic block may be a die-cast metallic block. 
     The contact elements are disposed in the first through-holes, respectively. Each of the contact elements comprises a support portion having opposite front and rear ends, a contact portion extending from the front end of the support portion, and a terminal portion extending from the rear end of the support portion. 
     Each of the insulator sleeves is fitted on the support portion of each of the contact elements, while being fitted in each of the first through-holes. And thereby, the contact elements are stationarily supported in the first through-holes, respectively, in a state that the contact elements are electrically insulated from the metallic block. Thus, the contact elements and the metallic block function as coaxial inner conductors and a coaxial common outer conductor, respectively. 
     With this structure, the number of parts comprising the multi-coaxial connector decreases, because the metallic block is common to all of the contact elements and functions as a coaxial common outer conductor. Beside that, such connector is manufactured, by fitting the insulator sleeve on the support portion of each contact element and then inserting the contact element together with each sleeve into each first through hole of the metallic block. That is, manufacturing process becomes easy, according to one aspect of the present invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a conventional connector, a part of which is shown broken away; 
     FIG. 2 is a cross-sectional view of a conventional connector illustrated in FIG. 1; 
     FIG. 3 is a perspective and enlarged view for use illustrating L-shaped casings as outer conductors in FIGS. 1 and 2; 
     FIG. 4 is a rear perspective view illustrating a multi-coaxial connector according to a preferred embodiment of this invention, being mounted onto a circuit board; 
     FIG. 5 is a disassembled perspective view of the connector illustrated in FIG. 6; 
     FIG. 6 is a cross-sectional view of a mating connector of the connector illustrated in FIG. 4; 
     FIG. 7 is a front view of the connector illustrated in FIG. 4; 
     FIG. 8 is a partially exploded plane view of the connector illustrated in FIG. 4; 
     FIG. 9 is a cross-sectional view of the connector illustrated in FIG. 4; 
     FIG. 10 is a cross-sectional view of an insulator housing of the connector illustrated in FIG. 4; and 
     FIG. 11 is a partially enlarged cross-sectional view for use in describing of manufacturing process of the connector illustrated in FIG.  4 . 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Prior to description of embodiments of this invention, brief description of a conventional one of multi-coaxial connectors will at first be made for a better understanding of this invention. 
     Referring to FIGS. 1 through 3, the conventional connector  1  is mounted on a printed circuit board  2  and comprises a housing  11 , a portion of which is shown broken away. In the illustrated connector  1 , the housing  11  carries two rows of three coaxial contact elements  12 . Herein, the connector  1  is to be removably coupled with a mating connector, which also has two rows of three inner and outer coaxial conductor, although not shown. 
     Each of coaxial contact elements  12  comprises a tubular inner contact part  14  shown in broken lines, a cylindrical outer contact part  13  surrounding the tubular inner contact part  14 . The cylindrical outer contact parts  13  has radially projecting lips  28  for locking the coaxial contact elements  12  to the housing  11 , and are connected to L-shaped casings  22 ,  23 . The tubular inner contact parts  14  are connected to L-shaped contact elements  26 . 
     The L-shaped casings  22  and  23  are manufactured from sheet metal and are connected to the outer contact part  13  by means of spot welds which are diagrammatically indicated by open circles  29  in FIGS. 1 and 2. The L-shaped casings  22  and  23  are each provided with two pin-type connecting ends  24  for connecting to the printed circuit board  2 . One end of the L-shaped contact element  26  is also connected to the printed circuit board  2 . Thus, the conventional connector  1  can establish the connection a plurality of the coaxial cables and the printed circuit board  2 , by being mounted on the board  2  and by being connected to the mating connector. 
     However, the conventional connector requires a pair of inner and outer contact parts  14 ,  15  of the coaxial contact elements  12  at every coaxial cable. 
     Now, explanation of a preferred embodiment of this invention will be made with reference to drawings, applying this invention to a multi-coaxial connector. 
     Referring to FIGS. 4 and 5, a multi-coaxial connector  3  is mounted on a circuit board  4 , and is coupled, at its front side, with a mating connector  100  shown in FIG. 6, which accommodates six coaxial cables  120  in this embodiment. Such multi-coaxial connector  3  comprises an insulator housing  5  with an open rear end  53 , a metallic block  6  with a front end surface fitted into the housing  5  through the open rear end  53 , as shown in FIG.  5 . For example, the insulator housing  5  is made of plastic material. 
     The metallic block  6  further has a rear end surface and six through-holes  61  which are formed in the metallic block  6  to extend in parallel with each other between the front and rear ends of the metallic block  6 . In this embodiment, the through-holes  61  are arranged two rows and three columns of a matrix as viewed from the rear end of the metallic block  6 , as shown in FIG.  5 . 
     The illustrated multi-coaxial connector  3  further has contact elements  71 ,  72  and insulator sleeves  8 , both six in number. 
     Each of the contact elements  71 ,  72  has a support portion, a contact portion  75 , and a terminal portion  77 . The support portion has opposite front and rear ends. Especially, in order for the connector  3  to be mounted on the circuit board  4  perpendicular to the connection face of the connector  3  and the mating connector, the support portion is bent at an intermediate portion thereof. Therefore, each of the contact elements  71 ,  72  forms an L-shape having a foot portion  73  ( 74 ) and a leg portion, that will be referred to as an L-shaped contact element  71  ( 72 ). The contact portion  75  extends from the front end of the support portion, to form a tip of the foot portion  73  ( 74 ). The terminal portion  77  extends from the rear end of the support portion, to form a tip of the leg portion. 
     Each of the insulator sleeves  8  is fitted on the foot portion  73  ( 74 ) of each of the L-shaped contact elements  71  ( 72 ) and is fitted in each of the through-holes  61 . Thus, the L-shaped contact elements  71 ,  72  are stationarily supported in the through-holes  61 , in a state that the L-shaped contact elements  71 ,  72  are electrically insulated from the metallic block  6 . Herein, the L-shaped contact elements  71 ,  72  function as coaxial inner conductors, while the metallic block  6  functions as a coaxial common outer conductor. 
     Now, further explanation, more in detail, will be made about the connector of this embodiment, together with FIGS. 7 through 11, too. 
     Referring to FIGS. 5,  7  and  10 , the insulator housing  5  is in a box-shaped form further having a front end wall opposite to the open rear end, and an upper wall. The front end wall is formed with six through-holes  57  which extend in a front-to-rear direction and correspond to the through-holes  61  of the metallic block  6 , as shown in FIGS. 5 and 7 through  10 . The upper wall is formed with an elastic finger  51  having stoppers  54  projecting downwards, as shown in FIGS. 5 and 10, while depressed portions  62  are formed on an upper outer surface of the metallic block  6 , as shown in FIG.  5 . The depressed portions  62  receive the stoppers  54 , respectively, when the insulator housing  5  is mounted on the metallic block  6  with the front end wall being disposed adjacent the front end surface of the metallic block  6 . Thus, the stoppers  54  and the depressed portions  62  are fixedly engage the insulator housing  5  to the metallic block  6 . 
     The illustrated insulator housing  5  further has two guide rims  52 , two hook-type projections  55 , and a connector positioning projection  56 . On the other hand, the mating connector  100  has two guide grooves  112  and two slots  111  both shown in FIG. 6, and the circuit board  4  has a connector positioning hole  41  shown in FIG.  9 . The guide rims  52  are formed on the upper wall of the insulator housing  5  to guide the mating connector  100 , by interacting with the guide grooves  112 . The hook-type projections  55  are formed at bottom of the insulator housing  5  to lock the connecting condition between the multi-coaxial connector  3  and the mating connector  100 , by being engaged with the slots  111 . The connector positioning projection  56  is engaged with the connector positioning hole  41  and, thereby, positions the multi-coaxial connector  3  on the circuit board  4 . 
     In this embodiment, the metallic block  6  is a die-cast metallic block and is in a rectangular form having a bottom surface perpendicular to the rear end surface. Such metallic block  6  is provided with three grooves  66  formed in the rear end surface thereof. Each of the grooves  66  corresponds to each of the columns of the through-holes  61  and is connected to the through-holes  61  and, extends to the bottom surface of the metallic block  6 . The leg portions of the respective contact  71 ,  72  are received in the groove  66 , while the terminal portion  77  projects outward from the bottom surface of the metallic block  6 . 
     The illustrated L-shaped contact elements  71 ,  72  are grouped into two types: large type and small type, that will be also referred to as large and small type contact elements, respectively. Specifically, the large type contact elements  71  are three and are disposed in through-holes  61  of upper row, while the small type contact elements  72  are three, too, and are disposed in through-holes  61  of lower row. To accommodate pairs of the large and the small type contact elements  71  and  72 , the grooves  66  comprise three stairlike grooves, each of which varies in a groove depth and extends in and along the three column of the through-holes  61 . In FIG. 5, a direction of the groove depth is shown as Y direction, while another direction of the column is shown as Z direction. Furthermore, the each stairlike groove  66  has a stairlike bottom of two steps corresponding to two rows of the through-holes  61 , to be more in the groove depth at a position corresponding to a lower one of the two rows. 
     The leg portions of the pair of L-shaped contact elements  71  and  72  are received, in common, in the corresponding one of the stairlike grooves  66  but are separated from each other to leave a space therebetween in a direction of the groove depth, namely Y direction in FIG.  5 . 
     The number of the stairlike grooves  66  may increase in accordance with the increasing of the number of columns, while the number of the steps of each stairlike groove  66  may increase in accordance with the increasing of the number of rows. Both of the increased stairlike grooves  66  and their steps can be formed in the same manner mentioned above. Furthermore, such variation of the stairlike grooves  66  allows the number of the L-shaped contact elements  71 ,  72  to increase. 
     The illustrated multi-coaxial connector  3  further comprises six insulator pieces  82 ,  84  which are classified into small and large types, that will be also called small and large insulator pieces hereinafter. The small insulator pieces  82  are mounted on the leg portions of the small contact elements  72 , while the large insulator pieces  84  are mounted on the leg portions of the large contact elements  71 . All of the insulator pieces  82 ,  84  are fitted in the stairlike grooves  66  at the steps thereof, respectively, so as to electrically insulate the leg portions of the contact elements  71 ,  72  from the metallic block  6 . In detail, the small insulator pieces  82  are located in deep portion of the stairlike grooves  66 , depending on the deep insertion of the small contact elements  72  into the metallic block  6 . 
     Also, the illustrated multi-coaxial connector  3  further comprises a partitioning plate  91  disposed in the space between the leg portions of the pair of L-shaped contact elements  71 ,  72 . In this embodiment, the partitioning plate  91  is sandwiched by the pairs of the small and large insulator pieces  82 ,  84 , as shown in FIGS. 8 and 9. The partitioning plate  91  is made of, for example, metal material and has three protruding portions  92  protruding upwards, six pins  93  projecting downwards and two lateral projections  94  projecting to opposite side. The number of the partitioning plate  91  may increase, corresponding to the number of rows. 
     Each of the grooves  66  has opposite side walls  67  and opposite slits  68  in the side walls  67  to extend in a direction of the groove  66  extending, respectively. And also, the metallic block  6  further has bottom slits  63  in the bottom surface thereof to extend in a direction of the rows and to cross the grooves  66 . The protruding portions  92  of the partitioning plate  91  are fitted into the opposite slits  68  and the lateral projections  94  are fitted into the bottom slits  63 . Thus, the partitioning plate  91  is fixedly accommodated in the metallic block  6  with the pins  93  projecting from the bottom surface of the metallic block  6 . 
     Moreover, the illustrated multi-coaxial connector  3  comprises a rear end plate  95  mounted on the rear end of the metallic block  6 . The rear end plate  95  is made of, for example, metal material and has an engaging projection  96 , four positioning holes  97  and six projecting pins  98 . Herein, the metallic block  6  further has a cut-away portion  65  which is formed on an edge of the rear end surface. 
     The rear end plate  95  covers an entire rear end surface of the metallic block  6  with the engaging projection  96  engaged with the cut-away portion  65 . Furthermore, the metallic block  6  has four positioning projections  64  which are formed on the rear end surface of the metallic block  6  and are fitted into the positioning holes  97  of the rear end plate  95 , respectively. When the rear end plate  95  covers the rear end surface of the metallic block  6 , such positioning projections  64  are deformed to thereby fix the rear end plate  95  to the metallic block  6 . 
     With this structure, the number of parts comprising the multi-coaxial connector decreases, because the metallic block  6  is common to all of the contact elements  71 ,  72  and functions as a coaxial common outer conductor. 
     Beside that, such structure of the connector  3  is easy to manufacture. In detail, manufacturing process of the embodiment comprises the following six steps: 
     1) fitting the insulator sleeve  8  on the support portion of the respective contact element  71 ,  72 , 
     2) capping the front end surface of the metallic block  6  with the insulator housing  5 , 
     3) inserting the small contact elements  72  together with the insulator sleeves  8  into the lower through holes  61  of the metallic block  6 , respectively, 
     4) partitioning the stairlike grooves  66  with the partitioning plate  91 , 
     5) inserting the large contact elements  71  together with the insulator sleeves  8  into the upper through-holes  61  of the metallic block  6 , respectively, and 
     6) covering the rear end surface of the metallic block  6 , by engaging the positioning projections  64  with the positioning holes  97 , and then, by deforming the positioning projections  64 , as shown in FIG.  11 . That is, manufacturing process becomes easy, in accordance with the one aspect of the present invention.