FIELD OF THE INVENTION 
       [0001]    The present invention relates to a connector including a socket and a header which are coupled together and electrically connected to each other. 
       BACKGROUND OF THE INVENTION 
       [0002]    As shown in  FIG. 9 , there is conventionally available a connector including a socket  81  and a header  82  for electrically interconnecting printed wiring boards (not shown) (e.g., flexible printed circuit boards or rigid boards) to which they are respectively mounted (see, e.g., Japanese Patent Application Publication No. 2007-165195). In the following description, up-down and left-right directions will be defined on the basis of  FIG. 9  and the direction perpendicular to the up-down and left-right directions in  FIG. 9  will be referred to as “front-rear direction”. 
         [0003]    The socket  81  includes a substantially rectangular columnar socket body  811  made of an insulating material and a plurality of socket contact members  812 , made by bending a strip-shaped metal plate, held in the socket body  811 . 
         [0004]    The socket body  811  has a connection recess portion  811   a  formed on the upper surface thereof. The socket contact members  812  are arranged side by side within the connection recess portion  811   a  along the longitudinal direction (or the front-rear direction) of the socket body  811 . Furthermore, the socket body  811  has lead-out pathways  811   b  formed in the left and right side walls to communicate with the connection recess portion  811   a.  One-end portions of the socket contact members  812  extend through the lead-out pathways  811   b  and protrude outwards beyond the outer surfaces of the left and right side walls of the socket body  811 , respectively. 
         [0005]    The header  82  includes a header body  821  made of an insulating material and a plurality of header contact members  822 , made by being a strip-shaped metal plate, held in the header body  821 . 
         [0006]    If the header  82  is inserted into the connection recess portion  811   a,  the header contact members  822  make conductive contact with the socket contact members  812 , allowing the socket  81  and the header  82  to be electrically connected to each other. 
         [0007]    The tip end portions of the socket contact members  812  protruding from the outer surfaces of the respective side walls of the socket body  811  are arranged side by side along the front-rear direction and soldered to the corresponding wiring patterns of the printed wiring boards. In this regard, if the positions of the tip end portions of the socket contact members  812  are highly non-uniform in the up-down direction, it is likely that the connection state between the socket  81  and the printed wiring boards becomes unstable. 
         [0008]    For that reason, before soldering the socket  81  and the printed wiring boards together, it is necessary to measure the planarity of the tip end portions of the socket contact members  812  and to inspect whether the deviations of the tip end portions fall within a prescribed range. In this connection, as shown in  FIGS. 10A to 11 , the inspection is a gauge inspection conducted by use of a rail  91  on which the socket  81  is placed and a pair of inspection jigs  92  provided on one surface of the rail  91  in a spaced-apart opposing relationship with each other. The socket  81  is conveyed along the rail  91  by an air blown toward the socket  81 . 
         [0009]    The inspection jigs  92  are provided to oppose to each other in the direction perpendicular to the conveying direction of the socket  81  (namely, in the direction indicated by an arrow in  FIG. 10B ). The socket  81  conveyed passes through between the inspection jigs  92 . At this time, if the tip end portions of the socket contact members  812  pass through the gaps G between the rail  91  and the inspection jigs  92  without making contact with the inspection jigs  92 , it is determined that the socket  81  has a good quality (the deviation of the tip end portions is small). In contrast, if the socket contact members  812  make contact with the inspection jigs  92 , it is determined that the socket  81  has a poor quality (the deviation of the tip end portions is great). 
         [0010]    In this regard, the left-right dimension, i.e., width dimension, of the socket  81  in  FIG. 11  is assumed to be “L”. The protrusion length of the socket contact members  812  protruding beyond the socket body  811  is assumed to be “P”. The overlapping amount between the socket contact members  812  and the inspection jigs  92  is assumed to be “Q”. 
         [0011]    In the conventional connector mentioned above, a demand has existed for reduction in size. This requires the width L to be set small. In order to make the width L small, there is a need to reduce the protrusion length P of the socket contact members  812 . 
         [0012]    If the protrusion length P is set small as shown in  FIG. 12 , however, it becomes impossible to make the overlapping amount Q great enough (the overlapping amount Q is zero in  FIG. 12 ) although it is possible to reduce the width L. This poses a problem in that the inspection cannot be conducted in an accurate manner. Alternatively, an image inspection may be used as another inspection method. However, the image inspection is less accurate than the gauge inspection set forth above. 
       SUMMARY OF THE INVENTION 
       [0013]    In view of the above, the present invention provides a socket capable of enjoying reduction in size and allowing the planarity of socket contact members to be inspected with increased accuracy. 
         [0014]    In accordance with a first embodiment of the invention, there is provided a socket, including: a substantially rectangular columnar socket body made of an insulating material, the socket body including a connection recess portion defined on one surface thereof, side walls opposed to each other in a transverse direction and lead-out pathways formed in the side walls; and a plurality of socket contact members arranged side by side within the connection recess portion along a longitudinal direction, one-end portions of the socket contact members extending through the lead-out pathways and protruding outwards beyond an outer surface of at least one of the side walls of the socket body, wherein the socket body includes a depression portion formed on the side wall through which the socket contact members, protrude, the depression portion being formed at least around the socket contact members. 
         [0015]    The depression portion may be formed to continuously extend from one longitudinal end of the socket body to the other longitudinal end. The socket contact members may be protruding through the bottom surface of the depression portion. 
         [0016]    The depression portion may be formed around each of the socket contact members in a one-to-one relationship. 
         [0017]    The depression portion may include an inner wall surface being inclined to make an obtuse angle with respect to the bottom surface thereof. 
         [0018]    In accordance with a second embodiment of the invention, there is provided a connector, including: the socket described above and a header including a header body made of an insulating material and a plurality of, header contact members held in the header body, the header contact members arranged to make conductive contact with the socket contact members when the header is inserted into the connection recess portion of the socket. 
         [0019]    As summarized above, the present invention can provide a socket capable of enjoying reduction in size and allowing the planarity of socket contact members to be inspected with increased accuracy. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0020]    The objects and features of the present invention will become apparent from the following description of embodiments, given in conjunction with the accompanying drawings, in which: 
           [0021]      FIG. 1  is a section view showing a connector in accordance with a first embodiment of the present invention; 
           [0022]      FIG. 2  is a perspective view showing a header employed in the first embodiment; 
           [0023]      FIG. 3  is a perspective view showing a socket employed in the first embodiment; 
           [0024]      FIGS. 4A and 4B  are perspective views showing socket contact members employed in the first embodiment; 
           [0025]      FIG. 5  is a section view illustrating the socket of the first embodiment under inspection; 
           [0026]      FIG. 6  is another section view illustrating the socket of the first embodiment under inspection; 
           [0027]      FIG. 7  is a perspective view showing a socket in accordance with a second embodiment of the present invention; 
           [0028]      FIGS. 8A through 8C  are perspective views illustrating the socket of the second embodiment under inspection; 
           [0029]      FIG. 9  is a section view showing a conventional connector; 
           [0030]      FIGS. 10A ,  10 B and  10 C are perspective views illustrating the socket of the second embodiment under inspection; 
           [0031]      FIG. 11  is a section view illustrating the socket of the second embodiment under inspection; and 
           [0032]      FIG. 12  is a section view illustrating a socket with short socket contact members under inspection. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0033]    Embodiments of the present invention will now be described with reference to the accompanying drawings which form a part hereof. 
       First Embodiment 
       [0034]    A connector in accordance with the first embodiment will be described with reference to  FIGS. 1 through 6 . 
         [0035]    As shown in  FIG. 1 , the connector of the present embodiment includes a header  1  mounted to a first printed wiring board (not shown) and a socket  2  mounted to a second printed wiring board (not shown). The socket  2  includes a connection recess portion  21   a  into which the header  1  is removably inserted. If the header  1  is inserted into the connection recess portion  21   a  with the first and second printed wiring boards kept in an opposing relationship with each other, the first and second printed wiring boards are electrically connected to each other through the header  1  and the socket  2 . 
         [0036]    In the following description, the up-down direction and the left-right direction will be defined on the basis of  FIG. 1 . More specifically, the direction in which the header  1  is inserted into the connection recess portion  21   a  will be referred to as “downward direction”. The direction in which the header  1  is removed from the connection recess portion  21   a  will be referred to as “upward direction”. In other words, the term “up-down direction” used in the following description corresponds to the “insertion-removal direction” defined in the claims. The direction perpendicular to the paper surface in  FIG. 1  will be referred to as “front-rear direction”. 
         [0037]    As shown in  FIGS. 1 and 2 , the header  1  includes a header body  11 , header contact members  12  arranged and held in groups at the left and right sides of the header body  11  and ground contact members  13  electrically connected to the ground patterns of the first printed wiring board. 
         [0038]    The header body  11  is made of an insulating material such as a synthetic resin and formed into a substantially rectangular columnar shape. An internal recess portion  11   a  extending in the front-rear direction is defined on the lower surface of the header body  11 . 
         [0039]    Each of the header contact members  12  includes a first contact portion  121  exposed in the left or right outer surface of the header body  11 , a second contact portion  122  cooperating with the first contact portion  121  to form a U-shape to interpose the left or right wall of the internal recess portion  11   a  between the first and second contact portions  121  and  122 , the second contact portion  122  exposed inwards in the internal recess portion  11   a , and a mounting-purpose terminal portion  123  extending outwards from the upper end of the second contact portion  122  in the left or right direction, passing through the bottom surface of the internal recess portion  11   a  and protruding along the upper end surface of the header body  11  in the left or right direction. The respective header contact members  12  are held in the header body  11  by, e.g., insert-molding. By soldering the terminal portions  123  to the conductive patterns provided in the first printed wiring board, the header contact members  12  are electrically connected to the first printed wiring board. 
         [0040]    Each of the ground contact members  13  includes a substantially U-shaped body-held portion  131  held within the header body  11  and a terminal portion  132  soldered to the ground pattern, the terminal portion  132  protruding from the upper end of the body-held portion  131  and extending along the upper end surface of the header body  11  in the left or right direction. 
         [0041]    As shown in  FIGS. 1 and 3 , the socket  2  includes a socket body  21  having a connection recess portion  21   a  formed on the upper surface thereof, and socket contact members  22  held within the connection recess portion  21   a.    
         [0042]    The socket body  21  is made of an insulating material such as a synthetic resin and formed into a substantially rectangular columnar shape. An internal raised portion  21   c  extending in the front-rear direction protrudes from the substantially central area of the connection recess portion  21   a.  On the left and right inner walls of the connection recess portion  21   a,  first contact member receiving grooves  21   b  for partially receiving the socket contact members  22  are formed side by side along the front-rear direction. On the left and right side surfaces of the internal raised portion  21   c,  second contact member receiving grooves  21   d  for partially receiving the socket contact members  22  are formed side by side along the front-rear direction. 
         [0043]    On the bottom surface of the connection recess portion  21   a  of the socket body  21 , guide grooves  21   e  communicating with the first contact member receiving grooves  21   b  and the second contact member receiving grooves  21   d  are formed in the positions corresponding to the respective socket contact members  22 . The guide grooves  21   e  are formed to extend in the left-right direction from the left and right ends of the bottom surface of the socket body  21  toward the center of the bottom surface. 
         [0044]    The lower end portions of the left and right side walls of the socket body  21  are continuously cut away along the front-rear direction to form depression portions  21   f  depressed more inwardly than the upper end portions of the left and right side walls. The depression portions  21   f  have a substantially rectangular cross section. 
         [0045]    The socket contact members  22  are held in the socket body  21  so that, when the header  1  is inserted into the connection recess portion  21   a,  the socket contact members  22  can make conductive contact with the header contact members  12  in a one-to-one relationship. 
         [0046]    In the present embodiment, the header contact members  12  and the socket contact members  22  are respectively formed by bending elongated metal plates having elasticity and conductivity. The header contact members  12  and the socket contact members  22  are arranged back and forth in two left and right rows and provided in plural sets, the width of the header contact members  12  and the socket contact members  22  extending in the same direction as the front-rear direction. 
         [0047]    As shown in  FIGS. 4A and 48 , each of the socket contact members  22  includes a mounting-purpose terminal portion  221  protruding more outwardly than the socket body  21  in the left-right direction, the thickness of the terminal portion  221  extending in the same direction as the up-down direction, a body-held portion  222  held in the socket body  21 , the body-held portion  222  extending upwards from one left or right inner end of the terminal portion  221 , a first connection portion  223  extending from the upper end of the body-held portion  222  to become distant from the terminal portion  221 , a first contact portion  224  extending downwards from the tip end of the first connection portion  223  to make contact with the first contact portion  121  of each of the header contact members  12 , a second connection portion  225  extending from the lower end of the first contact portion  224  to become distant from the body-held portion  222 , and a second contact portion  226  extending upwards from the tip end of the second connection portion  225  to make elastic contact with the second contact portion  122  of each of the header contact members  12  in such a fashion that each of the header contact members  12  is interposed between the first contact portion  224  and the second contact portion  226 . The left-right direction is defined as a terminal direction in the claims. 
         [0048]    A raised engaged portion  224   a  of curved surface shape protruding away from the body-held portion  222  more distantly in the left-right direction than the remaining portions of the first contact portion  224  is provided in the upper end extension of the first contact portion  224 . When the header  1  is completely engaged with the socket  2 , only the raised engaged portion  224   a  of the first contact portion  224  makes contact with the corresponding one of the header contact members  12 . 
         [0049]    The second connection portion  225  is inclined upwards as it extends away from the first contact portion  224 . Thus, the second connection portion  225  is elastically deformable so that the end portion thereof adjoining to the second contact portion  226  can be displaced downwards with respect to the end portion thereof adjoining to the first contact portion  224 . 
         [0050]    The tip end of the second contact portion  226  is bent toward the second connection portion  225  so that the second contact portion  226  can have a J-shape. This bending work creates a convex surface  226   a  making elastic contact with the corresponding one of the header contact members  12 . Each of the socket contact members  22  is attached to the socket body  21  from below the socket body  21  by causing those portions from the body-held portion  222  to the second contact portion  226  to pass through each of the guide grooves  21   e.  At this time, the terminal portion  221  of each of the socket contact members  22  is received within the corresponding one of the guide grooves  21   e.  The tip end of the terminal portion  221  protrudes outwards from the lower end of the left or right wall of the socket body  21  through each of the guide grooves  21   e.  In other words, the socket contact members  22  protrude from the lower ends of the depression portions  21   f.    
         [0051]    The body-held portion  222  and the first connection portion  223  of each of the socket contact members  22  are received within each of the first contact member receiving grooves  21   b.  The raised engaged portion  224   a  elastically protrudes from each of the first contact member receiving grooves  21   b.  Moreover, the second contact portion  226  of each of the socket contact members  22  is received within each of the second contact member receiving grooves  21   d . The upper end extension of the second contact portion  226  elastically protrudes from each of the second contact member receiving grooves  21   d.    
         [0052]    In this regard, press-fit bulge portions  222   a  and  224   b  are formed in the vertically middle extensions of the body-held portion  222  and the first contact portion  224  of each of the socket contact members  22  to protrude from the transverse opposite edges thereof in the transverse direction, i.e., in the front-rear direction. Each of the socket contact members  22  is held in the socket body  21  by press-fitting the press-fit bulge portions  222   a  and  224   b  between the inner surfaces of each of the first contact member receiving grooves  21   b  opposing in the front-rear direction. In this connection, the upper and lower end surfaces of the press-fit bulge portions  222   a  and  224   b  are inclined in the front-rear direction so that the protrusion dimension thereof is reduced toward the upper end lower ends. These inclined surfaces are guided by the inner surfaces of each of the first contact member receiving grooves  21   b , whereby each of the socket contact members  22  can be moved into a specified position with ease. 
         [0053]    A raised engaging portion  121   a,  which can override the raised engaged portion  224   a  of each of the socket contact members  22  when the header  1  is inserted into the connection recess portion  21   a,  is formed in the first contact portion  121  of each of the header contact members  12  to protrude outwards in the left-right direction. With this configuration, a worker can feel a clicking sense when the raised engaging portion  121   a  overrides the raised engaged portion  224   a.  The raised engaged portion  224   a  is positioned above the raised engaging portion  121   a  when the header  1  and the socket  2  are engaged with each other. Thus, a holding force is generated between the header  1  and the socket  2 . An inclined surface with a protrusion dimension gradually increasing upwards is formed in the lower end portion of the raised engaging portion  121   a.  When the header  1  is inserted into the connection recess portion  21   a,  the raised engaged portion  224   a  is slid on the inclined surface, thereby reducing the force required in inserting the header  1 . This makes it easy to connect the header  1  and the socket  2  together. 
         [0054]    In the second contact portion  122  of each of the header contact members  12 , a vertically elongated shelter recess portion  122   a  having a substantially V-like shape is formed on the surface of the second contact portion  122  opposing to the inner wall surface of the internal recess portion  11   a  of the header body  11 . In this regard, the outer surface of the second contact portion  226  of each of the socket contact members  22  has a curved surface shape with the transverse middle portion thereof protruding more outwardly than the lateral end portions thereof. As a result, when the header  1  and the socket  2  are connected together, the second contact portion  226  of each of the socket contact members  22  makes elastic contact with the open edge of the shelter recess portion  122   a.  Therefore, even if a foreign material adheres to the second contact portion  122  or  226  of each of the header contact members  12  or the socket contact members  22 , the foreign material is shoved into the shelter recess portion  122   a  by the second contact portion  226  as the header  1  is inserted into the connection recess portion  21   a.  This eliminates the possibility that the foreign material is caught between the header contact members  12  and the socket contact members  22 . The reliability in, connection is enhanced by the shelter recess portion  122   a.    
         [0055]    In this connection, the planarity inspection for the socket contact members  22  is performed in the same manner as in the prior art example. As shown in  FIGS. 10 through 12 , the socket  2  is conveyed on and along a rail  91  by an air blown toward the socket  2 . Then, the socket  2  is moved between a pair of inspection jigs  93  so that the socket contact members  22  can pass through the gaps G between the rail  91  and the inspection jigs  93 . Referring to  FIG. 5 , the inspection jigs  93  include insertion protrusions  931  formed in the lower end areas of the mutually opposing surfaces thereof. A slant surface  931   a  is formed in the upper end portion of each of the insertion protrusions  931 , the slant surface  931   a  being inclined outwards as it goes upwards. 
         [0056]    With the connector of the present embodiment configured as above, the depression portions  21   f  are formed in the lower end extensions of the left and right side walls of the socket body  21 . The terminal portions  221  of the socket contact members  22  protrude outwards from below the depression portions  21   f.  Therefore, if the socket  2  is conveyed between the inspection jigs  93  during the planarity inspection as shown in  FIG. 5 , the insertion protrusions  931  of the inspection jigs  93  are inserted into the depression portions  21   f  of the socket body  21 . Thus, the insertion protrusions  931  and the terminal portions  221  are overlapped with each other within the depression portions  21   f.  In other words, it becomes possible to obtain an overlapping amount Q of the terminal portions  221  of the socket contact members  22  and the insertion protrusions  931  of the inspection jigs  93  in the up-down direction, in the spaces between the bottom surfaces of the depression portions  21   f  and the tip ends of the socket contact members  22 . Accordingly, even if the protrusion length P of the socket contact members  22  from the socket body  21  is reduced, it is possible to sufficiently increase the overlapping amount Q of the terminal portions  221  of the socket contact members  22  and the inspection jigs  93 . This assists in reducing the width L of the socket  2 . In a nutshell, the socket of the present embodiment is capable of enjoying reduction in size and allowing the planarity of the socket contact members  22  to be inspected with increased accuracy. 
         [0057]    Since the depression portions  21   f  are continuously formed in the arrangement direction of the socket contact members  22  (namely, in the front-rear direction), the insertion protrusions  931  of the inspection jigs  93  can move through the depression portions  21   f  in the front-rear direction. Accordingly, the planarity inspection can be conducted with ease by merely inserting the insertion protrusions  931  of the inspection jigs  93  into the depression portions  21   f  and displacing the socket  2  in the front-rear direction. This makes it possible to shorten the inspection time and to reduce the number of inspection steps. 
         [0058]    Referring to  FIG. 6 , the upper end portion of each of the depression portions  21   f  may be a slant surface inclined upwards and outwards along the slant surface  931   a  of each of the insertion protrusions  931 . In other words, the bottom surface of each of the depression portions  21   f  makes an obtuse angle with respect to the upper inner surface thereof. In this modification, the quantity of the material cut away from the socket body  21  to form the depression portions  21   f  can be reduced as compared with the socket body  21  shown in  FIG. 5 . It is also possible to increase the strength of the socket body  21 . 
       Second Embodiment 
       [0059]    A socket in accordance with the second embodiment of the present invention will be described with reference to  FIG. 7 . In the following description, the up-down direction and the left-right direction will be defined on the basis of  FIG. 7 . The direction perpendicular to the up-down direction and the left-right direction will be referred to as “front-rear direction”. 
         [0060]    The connector of the present embodiment differs from the connector of the first embodiment in that the socket body  21  includes a plurality of depression portions  21   g  independently formed on the left and right side walls thereof in a one-to-one relationship with the socket contact members  22 . Other configurations remain the same as those of the first embodiment. The same components will be designated by like reference numerals and will be omitted from description. 
         [0061]    In the present embodiment, as shown in  FIG. 7 , depression portions  21   g  are formed in the lower end areas of the left and right side walls of the socket body  21  and are arranged at a substantially equal interval along the front-rear direction with partition walls  21   h  left between the depression portions  21   g.  In this regard, the lower ends of the depression portions  21   g  are in communication with the guide grooves  21   e.  The socket contact members  22  protrude from below the respective depression portions  21   g.    
         [0062]    When the planarity inspection is conducted with respect to the socket  2  configured as above, the socket  2  placed on a rail  91  is conveyed along the rail  91  by an air and is stopped between a pair of inspection jigs  94  as illustrated in  FIG. 8 . In this regard, the inspection jigs  94  are kept spaced apart from the rail  91  in the direction perpendicular to the conveying direction of the rail  91  until the socket  2  is conveyed to between the inspection jigs  94 . If the socket  2  arrives between the inspection jigs  94  as illustrated in  FIG. 8A , the inspection jigs  94  are moved toward the socket  2 . 
         [0063]    The inspection jigs  94  include insertion protrusions  932  formed in the lower end areas of the mutually opposing surfaces thereof and arranged side by side along the conveying direction of the rail  91 . The interval of the insertion protrusions  932  is equal to the interval of the socket contact members  22 . Therefore, if the inspection jigs  94  are moved toward the socket  2 , the insertion protrusions  932  are inserted into the respective depression portions  21   g  as illustrated in  FIG. 8B . The socket  2  is determined to have a good quality if the inspection jigs  94  do not make contact with the socket contact members  22 . Otherwise, the socket  2  is determined to have a poor quality. If the inspection comes to an end, the inspection jigs  94  are moved away from the socket  2  as illustrated in  FIG. 8C . Thereafter, the socket  2  is conveyed along the rail  91 . 
         [0064]    With the socket of the present embodiment configured as above, the depression portions  21   g  are formed only in the minimum areas of the socket body  21  required in conducting the planarity inspection of the socket contact members  22 . Accordingly, the socket of the present embodiment is capable of allowing the planarity inspection to be conducted with increased accuracy and reducing the quantity of the material cut away from the socket body  21 , in proportion to the quantity of the partition walls  21   h  remaining in the socket body  21 . Consequently, it is possible to increase the strength of the socket body  21 . 
         [0065]    While the invention has been shown and described with respect to the embodiments, it will be understood by those skilled in the art that various changes and modification may be made without departing from the scope of the invention as defined in the following claims.
A socket includes a substantially rectangular columnar socket body made of an insulating material and the socket body including a connection recess portion defined on one surface thereof. Side walls opposed to each other in a transverse direction and lead-out pathways formed in the side walls. The socket further includes a plurality of socket contact members arranged side by side within the connection recess portion along a longitudinal direction. One-end portions of the socket contact members extend through the lead-out pathways and protruding outwards beyond an outer surface of at least one of the side walls of the socket body. The socket body includes a depression portion formed on the side wall through which the socket contact members protrude and the depression portion being formed at least around the socket contact members.