Abstract:
A connector has a board with a plurality of contact pads electrically connected to a plurality of signal lines on one side. The connector also has a modularized structural unit on the other side. The structural unit includes a plurality of spring contacts as the mate to which the contact pads are electrically connected. The connector further has a shaft provided near the central part of the board and perpendicular to the board and a roller provided on the structural unit. To combine the contact pads and the contacts, the shaft is rotated to cause the rollers to engage with a projecting part provided at the tip of the shaft. The roller is provided higher in position than the circuit board on which the connector is to be mounted.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]    This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2002-188407, filed Jun. 27, 2002, the entire contents of which are incorporated herein by reference. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    1. Field of the Invention  
           [0003]    This invention relates to a connector usable in, for example, medical instruments, such as ultrasonic diagnostic equipment, semiconductor testing equipment, computers, and industrial equipment with a multicore electric input/output section, such as communications equipment.  
           [0004]    2. Description of the Related Art  
           [0005]    More particularly, this invention relates to a multicore connector with a plug and a receptacle used for an electrical connection between electronic apparatuses utilizing a multi-core cable or the like.  
           [0006]    Sophisticated electronic apparatuses, including medical instruments, semiconductor testing equipment, computers, and communications equipment, have been getting smaller in size and more sophisticated. In addition, the signals they have to transmit and receive have become more diversified and complex. Thus, the input/output and transmission/reception cables of a plurality of electronic apparatuses connected to one another tend to have more cores, which thus requires multicore connectors smaller in size, higher in density, and of higher reliability.  
           [0007]    Multicore connectors involve connection of many contact parts. When a plug and a receptacle are connected to each other, and when the plug is pulled out of the receptacle, it is desirable that the insertion force and the pulling force be very small. Furthermore, there have been demands for long-service-life connectors with less wear of the contact parts.  
           [0008]    [0008]FIG. 11 shows an example of a conventional multicore connector  100 . The multicore connector  100  is composed of a plug  101 , connected to one (not shown) electronic apparatus, and a receptacle  102 , connected to another (not shown) apparatus. When they are connected to each other, after the plug  101  is inserted into the receptacle  102  (with zero insertion force) and joined with each other, a handle  103  is turned, thereby rotating a cam shaft  104  provided on the plug central part.  
           [0009]    By this process, the action of a cam  105  provided in the lower part of the cam shaft  104  slides an actuator  106  in the lateral direction, thereby moving a contact  108  formed at the tip of a contact pin  107  to a contact  109  of the receptacle  102  in such a manner that the contact  108  comes into contact with the contact  109 . Each contact pin is displaced elastically, causing the contact  108  of the plug  101  to press against the corresponding contact  109  of the receptacle  102 , which connects the plug and receptacle to each other electrically. The rotation of the cam shaft  104  sets a lock between the plug  101  and the receptacle  102 , which secures the plug  101  to the receptacle  102  reliably.  
           [0010]    For instance, in an ultrasonic apparatus, when this type of connector is used to connect the signal cable of the ultrasonic sensor to the apparatus body, the following approach is used: the receptacle  102  is fixed to the circuit board (not shown) in the ultrasonic apparatus and each contact terminal  110  is soldered to the corresponding wire on the circuit board, and the plug  101  is engaged with the receptacle  102 , thereby making an electrical connection. To wire the plug with a multicore cable, the cores of the multicore cable (not shown) are contact-bonded or soldered to contact terminals  111 . Alternatively, the contact terminals are mounted on a specific circuit board. Then, a cable is drawn out of the wiring of the circuit board. However, in the conventional multicore connector of FIG. 11, the contacts  108  and  109  are long, which permits crosstalk or a similar problem to occur between the contacts, depending on usage.  
           [0011]    [0011]FIG. 12 shows a conventional example of a multicore connector  200  developed to solve the crosstalk problem or the like. The multicore connector  200  is also composed of a plug  201  and a receptacle  202  as the connector of FIG. 11. FIG. 12 shows a state where the plug  201  and the receptacle  202  are connected to each other electrically in the conventional example.  
           [0012]    The plug  201  has a plug housing  203 . In the lower part of the housing  203 , there is provided a plug board  204  composed of a multilayer wiring insulating board. On the top surface of the plug board  204 , a plurality of electrode pads  205  are formed which are to be connected to the individual cores (not shown) of the multicore cable extending from one electronic apparatus to be connected. A plurality of contact pads  206  corresponding to the electrode pads  205  are formed on the bottom surface of the plug substrate  204 , which connects the contact pads  206  corresponding to the electrode pads  205  to the electrode pads  205  electrically inside the plug board  204 . The plug  201  further has a cam shaft  207  provided rotatably in the central part of the plug. At the top of the cam shaft, there is provided a handle  208  for pressing the plug  201  against the inside of the receptacle  202  and at the same time, rotating the cam shaft  207 .  
           [0013]    Moreover, the housing  203  is provided with a spring support section  209  for actuating the cam shaft  207  upward, and a spring  220 . The cam shaft  207  has a ringed brim projecting from its side which presses against the spring  220 .  
           [0014]    The receptacle  202  has a receptacle housing  209 . In the lower part of the housing  209 , a receptacle board  210  is provided. On the top surface of the receptacle board  210 , a plurality of contact pads  211  (or contact strips) to be pressed against the contact pads  206  of the plug are formed. On the bottom surface of the receptacle board  210 , a plurality of electrode sections  213  are formed which are internally connected to the contact pads  211  and electrically connected to the printed wiring board  212  of the other electronic apparatus.  
           [0015]    The receptacle  202  further has a stiffener  214  serving as a support member in its lower part. The printed wiring board  212  of the other electronic apparatus is inserted between the stiffener  214  and the bottom surface  215  of the receptacle housing  209  and then screwed there (not shown), thereby fixing the receptacle  202  to the circuit board  212 . The receptacle  202  is provided with a set of folding doors  222  on both sides. When the plug  201  is not inserted, the doors  222  are turned horizontally to close the receptacle  202 .  
           [0016]    To connect the plug  201  and the receptacle  202 , the plug  201  is inserted into the receptacle  202  in such a manner that the doors  222  are forced open left and right and the cam shaft  207  is further pressed downward, opposing the actuation of the spring  220 . Then, the cam shaft  208  is rotated with the handle  208 , thereby pulling a projecting part  216  sticking out of the cam shaft  207  under the locking surface  218  of the central concave part  217  of the bottom surface of the stiffener  214 . As a result, the elastic force of the spring  220  makes an electrical connection between the individual contact pads  206 ,  211  of the plug and receptacle. To remove the plug  201 , the cam shaft  207  is pressed downward, opposing the actuating force of the spring  220 , and then is rotated in the opposite direction, thereby unlocking the projecting part  216 .  
           [0017]    In the conventional multicore connector  100  of FIG. 11, turning the handle causes the contacts to move in the lateral direction by means of the cam mechanism near the center, which assures the operation capability with a ZIF (zero insertion force) structure. Since the contact pins  107 ,  109  are deformed elastically to make contact with one another, as the number of cores increases, the rotational torque of the cam shaft  104  becomes larger at the time of engagement, which is a problem. Furthermore, since spring actions are needed, this lengthens the signal line, making interference, such as crosstalk, liable to take place in the transmission characteristic of the electric signals, which tends to have an adverse effect on the transmission of high-speed signals.  
           [0018]    Furthermore, in a conventional multicore connector  200  of FIG. 12, since no contact pin is used, the signal lines in the longitudinal direction become shorter, enabling the height of the connectors in the longitudinal direction to be reduced. However, to increase the rigidity of the connector  200  and connect the connector  200  to the circuit board  212  on which the connector  200  is to be mounted, a stiffener  214  to fix the connector  200  to the board  212  has to be provided on the back of the board  212 . Furthermore, an opening  223  has to be made in the board. As a result, the connector  200  is made larger on the whole and the parts mounting area is made smaller, which is a problem. In addition, there is another problem: even if the plug housing  203  and receptacle housing  209  are made of a metal, it is difficult to make electrical connection to cause them to be grounded completely.  
           [0019]    An object of the present invention is to provide a multicore connector which makes the rotational torque of the cam shaft smaller and shortens the signal lines to improve the EMI characteristic, or the transmission characteristic of electric signals, and prevent interference, such as crosstalk, and which is suitable for the transmission of high-speed signals. Another object of the present invention is to provide a multicore connector which reduces the number of parts to be mounted on an electronic apparatus, makes the parts mounting area smaller by downsizing the whole connector, and enables the plug housing and receptacle housing to be grounded completely.  
         BRIEF SUMMARY OF THE INVENTION  
         [0020]    As explained in embodiments of the present invention shown in FIGS.  1  to  10 , such contact pads  17  as contact the electrical contact sections  34  of a receptacle  2  directly to make an electrical connection are formed on one side of the plug board  5  of a plug  1 . On the mating receptacle  2 , a plurality of spring contactors, or receptacle contacts  34 , are formed. By doing this, the signal lines on the whole connector can be shortened.  
           [0021]    The contacts  34  on the receptacle  2  side can be modularized in units of a specific number of contacts as shown in FIG. 6. Although the present invention is not limited to the modularization of contacts, use of a structure with a plurality of contact modules enables a great many contact sections to be formed. Use of a plurality of contact modules conforming to the same standard according to the number of contacts needed makes it possible to form various types of multicore connectors easily according to the number of cores needed. Consequently, it is possible to give flexibility to the design.  
           [0022]    Furthermore, a plurality of spring contacts bringing the shell section of the plug frame  3  and the receptacle housing  11  into contact with each other, or grounding plate springs  25  can be provided on the inner periphery of the receptacle housing  11 . This structure makes a reliable electrical connection between the plug frame  3  and the grounded receptacle housing  11 , which provides a structure capable of improving the EMI characteristic of the multicore connector related to the present invention.  
           [0023]    In addition, a grounding conductive pattern  30  is provided on the periphery of the plug board  5 , which provides a structure where the shell section of the plug frame  3  connected to the grounding pattern makes contact with a number of grounding springs provided around the module connector.  
           [0024]    A connector according to the present invention has a structure where an engaging section including rollers  15  for engaging the plug frame with the receptacle housing and a shaft  6  is provided inside the connector. For instance, as compared with a conventional multicore connector shown in FIG. 12, the plug pulling-in action can be completed only within the multicore connector. This makes it unnecessary to use the support member  214  provided under the conventional circuit board  212 .  
           [0025]    According to the present invention, there is provided a connector for connecting a plurality of signal lines to a specific electronic apparatus that uses the signal lines. The connector comprises: a first structural unit which includes a board having a plurality of contact pads to be electrically connected to the plurality of signal lines and a substantially hollow cylindrical shaft to rotate, the shaft passing through the board, extending perpendicular to the board and having a projecting part protruding from one side; and a second structural unit which includes a bottom, a plurality of spring contact sections provided on the bottom and a rotatable roller provided on the bottom, each of the spring contact sections facing, at one end, the corresponding one of the contact pads and being connectable, at the other end, to the specific electronic apparatus. The first structural unit can be inserted, in part, into the second structural unit. The roller comes close to the shaft when the shaft and a part of the first structural unit are inserted into the second structural unit. When the first structural unit is inserted, in part, into the second structural unit and the shaft is rotated through a specific angle, the projecting part comes to a position beneath to push the board against the contact sections. The contact pads therefore contact the contact sections, respectively.  
       
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING  
       [0026]    [0026]FIG. 1 is a perspective view, from diagonally above, of a plug and a receptacle constituting a multicore connector according to an embodiment of the present invention;  
         [0027]    [0027]FIG. 2 is a perspective view, from diagonally below, of the plug and receptacle constituting the multicore connector according to the embodiment;  
         [0028]    [0028]FIG. 3 is a detailed perspective view, from diagonally above, of the receptacle  2  of the multicore connector according to the embodiment;  
         [0029]    [0029]FIG. 4 shows a state where a plug board is assembled into a plug frame;  
         [0030]    [0030]FIG. 5 shows the bottom surface of the plug board with a plurality of contact pads;  
         [0031]    [0031]FIG. 6 is a perspective view of a contact module;  
         [0032]    [0032]FIG. 7 is a sectional view of the plug and receptacle which are combined completely;  
         [0033]    [0033]FIGS. 8A to  8 C are partly sectional views to help explain the operation of the multicore connector according to the embodiment;  
         [0034]    [0034]FIGS. 9A and 9B are partial sectional views to help explain the operation of the multicore connector according to the embodiment;  
         [0035]    [0035]FIGS. 10A and 10B are diagrams to help explain another embodiment of the present invention;  
         [0036]    [0036]FIG. 11 shows an example of a conventional multicore connector; and  
         [0037]    [0037]FIG. 12 shows another example of a conventional multicore connector. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0038]    Referring to the accompanying drawings, embodiments of the present invention will be explained. FIGS.  1  to  10  show multicore connectors according to embodiments of the present invention. In the detailed explanation below and the description of the drawings, like elements are indicated by like reference numerals.  
         [0039]    [0039]FIG. 1 is a perspective view, from diagonally above, of a plug  1  and a receptacle  2  constituting a multicore connector according to the present invention. The terms representing directions, including up, down, longitudinal, and lateral directions, used in this specification are used on the basis of examples shown in the accompanying drawings. Actually, the multicore connectors may be placed diagonally or upside down on the accompanying drawings.  
         [0040]    In FIG. 1, a plug  1  includes a plug frame  3  made of, for example, a metal member, so that at least its surface is conductive, a plug board  5  attached to the lower part of the plug frame  3  with, for example, screws  4  (see FIG. 2), and a cam shaft  6  composed of a substantially cylindrical shaft provided rotatably on a cylindrical section  9  formed in almost the central part of the plug board  5  with respect to the plug frame  3 .  
         [0041]    The cam shaft  6  is provided in the vertical direction with respect to the board  5 . As shown in FIG. 2, the cam shaft  6  passes through a through hole  28  made in the board  5 , with its lower part penetrating the board  5 . In the upper part of the cam shaft  6 , a handle  7  is fixed to the shaft  6  with a screw  8 . The handle  7  makes it easy to insert and remove the plug  1  into and from the receptacle  2  and enables the cam shaft  6  to rotate on its axis to fix the plug  1  to the receptacle  2 .  
         [0042]    A ring-shaped frame cover  10  is fixed to the upper part of the cylindrical section  9  with screws. Although it is desirable that the cam shaft  6  be formed in the central part of the plug frame  3  as shown in FIG. 1, it is not necessarily formed in the center.  
         [0043]    The receptacle  2  includes a receptacle housing  11  made of, for example, a metal member, so that at least its surface is conductive, a plurality of grounding plate springs  25  composed of, for example, elastic metal plates provided along the inner wall of the receptacle housing  11 , and a plurality of metal contact strips or contacts  34  provided in lines in the lower part of the receptacle housing  11 . The contacts  34  may be composed of a contact module formed by arranging a plurality of contact strips beforehand. As shown in FIG. 1, the contact module may be divided into groups, which may be used as contact modules  12 . It is desirable to divide the contact module in this way. The springs  25 , which are conductive, enable an electrical connection between the plug frame  3  and the receptacle housing  11 . The springs  25  are not limited to a plate-like shape bent convexly in the middle as shown in FIG. 1, and may have a coil-like shape.  
         [0044]    In the central part of the receptacle housing  11 , there is provided a substantially cylindrical bushing  13  with an opening  50  into which the lower part of the cam shaft  6  is inserted. While in the embodiment, the bushing  13  is formed separately from the receptacle housing  11  and then mounted on the receptacle housing  11 , the bushing  13  and the receptacle housing  11  may be formed integral.  
         [0045]    [0045]FIG. 2 is a perspective view of the plug  1  and receptacle  2 , both obliquely seen from below. The plug  1  and the receptacle  2  constitute a multi-core connector according to the invention. A pair of rod-like projecting parts  14  protrude from the lower part of the cam shaft  6 . The projecting parts  14  have an almost oval cross section and horizontally extend from the side of the cam shaft  6 . The projecting parts  14  are used in association with a pair of rollers  15  that are provided in the bushing  13  of the receptacle  2 . Thus, they work as a cam for pressing the lower part of the plug  1  against the upper part of the receptacle  2 . The cross section of the projecting parts  14  is not limited to an oval one. It may have any other appropriate shape, as long as the parts  14  can come to positions beneath he rollers  15  to push the rollers  15  upwards when they are rotated in a horizontal plane. For example, each part  14  may have a circular cross section or a rectangular cross section. Moreover, the number of projecting parts is not limited to two.  
         [0046]    As shown in FIG. 2, on the bottom surface  16  of the plug substrate  5 , a plurality of contact pads  17  are formed. In the lower part of the plug frame  3 , to protect the contact pads  17 , a protective cover  18  with a plurality of circular or almost rectangular openings  29  is provided in the lower part of the plug board  5  and fixed to the plug frame  3  with screws  4 . The lower part of the cam shaft  17  passes through the circular opening. In the rectangular openings, the corresponding contact pads  17  can be exposed.  
         [0047]    In the bottom  20  of the receptacle housing  11 , a plurality of almost rectangular holes  21  are made. Contact modules  12 , which will be explained by reference to FIG. 6, are pressed into the rectangular holes  21  from above. The way of mounting the contact modules  12  in the receptacle housing  11  is not limited to pressing the modules into the holes. In the lower part of the contact modules  12 , a plurality of connecting terminals  22  are so formed that they project downward. The connecting terminals  22  are for making an electrical connection with the electric wiring (not shown) or the circuit board (not shown) of such an electronic apparatus as a medical instrument, semiconductor testing equipment, a computer, and communication equipment.  
         [0048]    Furthermore, to make it possible to mount multicore connectors of the present invention in lines on the printed wiring board (not shown) of an electronic apparatus, for example, an alignment pin  23  and/or a mounting hole  24  may be provided on the bottom  20  of the receptacle housing  11 .  
         [0049]    [0049]FIG. 3 is a detailed perspective view, looked diagonally down from above, of the receptacle  2  of the multicore connector according to the present invention. Shown at left are four contact modules  12  pressed into holes  21  made in the bottom of the receptacle housing  11 . The way of mounting the modules  12  in the receptacle housing is not limited to pressing the modules into the holes, and may be, for example, fixing the modules with screws. Shown at right are four contact modules  12  before being pressed into the holes. The number of contact modules  12  used in the connector can be determined suitably according to the number of contacts.  
         [0050]    In FIG. 3, a projecting part or a shoulder  26  is formed on the side of each substantially rectangular hole  21  in the bottom  20  of the receptacle housing  11 . The projecting part or shoulder  26  is combined with a projecting brim  27  formed on the side of the contact module  12 , which determines the longitudinal position of the pressed-into contact module  12  with respect to the receptacle housing  11 .  
         [0051]    [0051]FIG. 4 shows a state where the plug board  5  with the through hole  28  through which the lower part of the cam shaft  6  is passed is assembled into the plug frame  3  on which the cam shaft  6  has been installed. A grounding conductive pattern  30  is formed on the periphery of the top surface  29  of the plug board  5 . The conductive pattern  30  contacts the shoulder  31  of the plug frame  3  which can be grounded as shown in FIG. 7, thereby grounding the plug board  5  reliably.  
         [0052]    The plug board  5  mounted on the plug frame  3  can be formed by, for example, using either a circuit board with the top-surface wiring and the bottom-surface wiring connected to each other in specified parts or a multilayer wiring circuit board. On the top surface  29  of the plug board, a plurality of electrical connecting parts (not shown) corresponding to the contact pads  17  are formed on the bottom surface. The individual core lines of the multicore cable, such as signal lines from the specified electronic apparatuses connected to a multicore connector of the present invention, are connected to the electrically connecting sections. The present invention is not restricted to the method of making an electrical connection. For instance, an electrical connection may be made by soldering the connections.  
         [0053]    [0053]FIG. 5 shows the bottom surface  16  of the plug board  5  with a plurality of contact pads  17 . The contact pads  17  are connected electrically to the corresponding electrically connecting parts on the top surface of the plug board via the internal wiring (not shown) of the plug board. The contact pads  17  may be formed by partly gold-plating the wiring section of the plug board  5  to assure a good contact state. Alternatively, the contact pads  17  may be made by using metal contact strips provided suitably on the plug board  5 . In the plug board  5 , a through hole  28  is made which enables the lower part of the cam shaft  6  to pass through.  
         [0054]    [0054]FIG. 6 is a perspective view of a contact module usable in the present invention. A plurality of grooves  33  passing through in an up and down direction are made in a frame section  32  made of an insulating material. In each groove  33 , a spring metal contact strip  34  is inserted, positioned by a suitable method, and fixed there. When the plug  1  is combined with the receptacle  2  completely, the top  35  of the metal contact strip  34  comes into contact with the contact pad  17  on the bottom surface  16  of the plug board  5 . The lower part of the metal contact strip  34  forms a connector terminal  22 . The connector terminal  22  is connected to the circuit board of an electronic apparatus with a multicore connector, or to a multicore cable.  
         [0055]    [0055]FIG. 7 is a sectional view of the plug  1  and receptacle  2  which are combined together completely. A ringed bearing plate  37  on which force acting in the direction of the axis of the cam shaft  6  during engagement is exerted is provided on a step part  36  looking to the upper part of the inner wall of the cylindrical section  9  of the plug  1 . With the plug  1  inserted in the receptacle  2 , the bearing plate  37  facilitates the rotation of the cam shaft  6 . The bearing plate  37  is so provided that it faces, in a up and down direction, a ringed projecting part  38  formed on the side of the cam shaft  6 , thereby limiting the downward movement of the cam shaft  6 .  
         [0056]    Inside the sidewall of the substantially cylindrical bushing  13  provided in the central part of the receptacle housing  11 , a pair of roller axes  44  is provided in such a manner the axes project horizontally with respect to the axis of the cam shaft  6 . A cylindrical roller  15  provided with a clearance so as to be close to the cylindrical side of the cam shaft  6  is mounted rotatably on the roller axes  44 .  
         [0057]    Further on the side of the cam shaft  6 , a rod-like projection  39  projecting laterally in the lower part of the frame cover  9  is preferably formed. When the plug  1  and the receptacle  2  are combined completely, the rod-like projection  39  fits in a specific position of the concave portion of the lower part of the frame cover  9 , thereby limiting the rotation of the cam shaft  6 .  
         [0058]    Furthermore, to clarify the on and off positions of the cam shaft  6 , a pair of plate-like return springs  41  are provided on the side of the cam shaft  6 . When the combination of the projecting parts  14  of the cam shaft  6  and the rollers  15  is unlocked to remove the plug  1 , the cam shaft  6  is actuated so that it may rotate back to the initial position.  
         [0059]    Furthermore, as shown in FIG. 7, the lower part  42  of the sidewall of the plug frame  3  can come into electrical contact with the top surface of the bottom of the receptacle housing  11  via the plate springs  25 . Therefore, after the plug  1  and the receptacle are combined, a reliable electrical continuity for grounding the plug  1  and receptacle  2  can be obtained.  
         [0060]    The operation of a multicore connector according to the present invention will be explained briefly by reference to FIGS. 8A to  8 C and FIGS. 9A and 9B. FIG. 8A is a sectional view of the plug  1  in the course of being inserted into the receptacle  2 . FIG. 8B is a sectional view of the plug  1  almost inserted in the receptacle  2 . FIG. 8C is a sectional view of the completed combination after the cam shaft  6  is rotated.  
         [0061]    [0061]FIG. 9A is a perspective view, from diagonally below, of the plug  1  almost inserted into the receptacle  2  before the rotation of the cam shaft, which corresponds to FIG. 8B. In FIG. 9A, the circuit board  46  of FIGS. 8A to  8 C is not shown. FIG. 9B is a perspective view of the completed combination after the cam shaft  6  is rotated, which corresponds to FIG. 8C. In FIGS. 8A to  8 C, the connecting terminals  22  actually used are connected to the wiring section (not shown) of the circuit board  46  of the electric apparatus with, for example, solder. The parts indicated by numeral  47  in FIGS. 8A to  8 C are a part of the bottom  20  of the receptacle housing  11 .  
         [0062]    The combination in the connector is carried out as follows: the plug  1  is inserted and pressed into the receptacle  2  (FIG. 8A) until the lower end  43  of the cam shaft  6  has reached a position deeper than the rollers  15  (FIG. 8B), then the shaft  6  is rotated, for example, clockwise about  100  degrees (FIG. 8C).  
         [0063]    Rotating the cam shaft  6  clockwise about 100 degrees with the handle  7  causes the pair of projecting parts  14  (see FIG. 8C) provided in the lower part of the cam shaft  6  to get into under the rollers  15  incorporated into the bushing  13  of the receptacle  2 , pushing up the lower part of the rotating surface of the rollers  15 . The rotation of the rollers  15  makes it easy for the projecting parts  14  to move to positions beneath the rollers  15 . Since the roller axes  44  are fixed, the projecting parts  14  are actually actuated downward by the rollers  15 . This enables the receptacle  2  to be pulled downwards into the body of the plug  1 .  
         [0064]    This makes it possible to bring the upper parts  35  of the spring contacts in the contact module  12  incorporated in the bottom  20  of the receptacle  2  into reliable electrical contact with the contact pads  17  provided on the bottom surface  16  of the board  5  of the plug  1 .  
         [0065]    At the same time, the grounding plate springs  25  mounted on the receptacle  2  are pressed by the lower part  42  of the peripheral part of the plug frame  3 . As a result, the lower part  42  of the sidewall of the plug frame  3  comes into electrical contact with the top surface of the bottom of the receptacle housing  11  via the springs  25 , thereby making a reliable electrical connection between the plug frame  3  and the receptacle housing  11 . As a result, grounding one of the plug  1  and the housing of the receptacle  2  by a suitable method makes it possible to ground the other at the same time. In addition, it is possible to ground the plug board  5  to which the conductive pattern  30  on the periphery contacting the shoulder  31  of the plug frame  3  contacts.  
         [0066]    To remove the plug  1  from the receptacle  2 , the cam shaft  6  is rotated counterclockwise about 100 degrees with the handle  7 , which is the reversal of insertion. Rotating the cam shaft  6  of the plug  1  counterclockwise causes the projecting parts  14  of the cam shaft  6  to come off the rollers  15  of the receptacle  2 , which enables the plug  1  to move upward. Therefore, pulling up the plug  1  enables the plug  1  to be unplugged from the receptacle  2 . At this time, the contact top  35  of the contact module  12  and the grounding plate springs  25  are separated from the corresponding contact parts, which breaks the individual electrical connections.  
         [0067]    [0067]FIGS. 10A and 10B show another embodiment of the present invention. FIGS. 10A and 10B are a plan view and a sectional view of the embodiment. A multicore connector of FIG. 10 further comprises a lid member  49  with a multicore cable insert section  48  in addition to the multicore connector of FIG. 1. The number of contact modules  12  is  6 , smaller than in FIGS.  1  to  9 .  
         [0068]    According to the present invention, the rotational torque of the cam shaft can be made smaller than the conventional multicore connectors. In addition, the signal lines in the contact section are made shorter, thereby improving the signal transmission characteristic and preventing interference, such as crosstalk, which makes it possible to provide a multicore connector suitable for the transmission of high-speed signals.  
         [0069]    Furthermore, it is possible to provide a multicore connector which reduces the number of parts to be mounted in an electronic apparatus, makes the parts mounting area smaller by downsizing the whole connector, and enables the plug housing and receptacle housing to be completely grounded.  
         [0070]    The present invention is not limited to the above embodiments and may be practiced or embodied in still other ways without departing from the spirit or essential character thereof.