BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a board connector for electrically connecting together circuit boards which are incorporated in, for example, a mobile telephone. 
   2. Description of the Prior Art 
   A plurality of circuit boards (PCBs, hereinafter referred to merely as “boards”) are incorporated in a mobile telephone. A conventional board connector for electrically connecting the boards to each other has the following configuration. One-end sides of plural socket contacts which are fixed in parallel to a socket are fixed to one of the boards by soldering, and the socket is mounted on the board. By contrast, one-end sides of plural socket contacts which are fixed in parallel to another socket are fixed to the other board by soldering, and the other socket is mounted on the other board. A plug in which one-end sides of plug contacts configured by plural thin conductors are fixed in parallel is fitted to the socket, and one-end sides of the plug contacts are contacted with and held by the socket contacts. Another plug to which the other-end sides of the plug contacts are fixed in parallel is fitted to the other socket, and the other-end sides of the plug contacts are contacted with and held by the other socket contacts. As a result, the boards are electrically connected to each other. 
   In the case where plural thin conductors are used as plug contacts in a board connector for electrically connecting together boards, an insulation plate which holds the plug contacts at regular intervals is disposed so as prevent the plug contacts from contacting with each other (Japanese Patent No. 2,959,094) 
   SUMMARY OF THE INVENTION 
   Problems to be solved by the invention are that, in a board connector, a narrow pitch of contacts of a plug and socket easily causes a trouble such as a contact failure between the contacts of the plug and socket due to dust or the like, and that multiplication of the number of pins by which the number of contacts is increased disables easy insertion and extraction of a plug. 
   In order to solve the problems, the board connector of the invention comprises: a plug in which one-end sides of plug contacts configured by plural thin conductors are fixed in parallel to a plug body made of an insulating material; a socket in which a plug fitting recess is disposed in a socket body made of an insulating material, socket contacts configured by plural thin conductors are fixed in parallel to the socket body, and movable contact pieces that are disposed in one-end sides of the socket contacts, and that are elastically displaceable are projected in the plug fitting recess; and a cover member which is attached to the plug to cover the plug and the socket that are in a fitting state. Contact portions of the plug and socket in the fitting state are covered by the cover member to cause dust and the like to hardly enter therein, thereby suppressing occurrence of a contact failure between the contacts of the plug and socket because of a narrowed pitch. 
   In the invention, preferably, the cover member is swingably attached to the plug via a fulcrum shaft. 
   Preferably, in one of the plug and the cover member, a protrusion which causes an end portion to continuously butt against another one of the plug and the cover member from one end to another end is disposed. According to the configuration, when the plug is inserted, the force of inserting the plug can be evenly transmitted from the cover member to the whole plug. Even when the number of contacts is increased as a result of multiplication of the number of pins, therefore, insertion of the plug can be easily performed. 
   Preferably, the board connector further comprises engaging means for, when the plug and the socket are fitted to each other, fixing the cover member to the socket. 
   Preferably, joining portions which, when the plug and the socket are fitted to each other, are joined to each other in a front side with respect to the fulcrum shaft are disposed in the socket and the cover member, and the plug is pulled up by swinging the cover member with setting the joining portion with the socket as a fulcrum. According to the configuration, the plug can be pulled up by a small force with using the cover member as a lever. Even when the number of contacts is increased as a result of multiplication of the number of pins, therefore, extraction of the plug can be easily performed. 
   Preferably, in addition to the plug, the socket, and the cover member constituting the board connector, the board connector further comprises another plug, another socket, and another cover member constituting another board connector having a same structure as the board connector, other-end sides of the plug contacts are fixed in parallel to a plug body of the other plug, the socket is mounted on a board, the other socket is mounted on another board, and the boards are electrically connected to each other by the board connector and the other board connector. 
   Preferably, the board connector further comprises an insulating member made of an insulating material, plural thin contact grooves through which plug contacts between the plug and the other plug are to be passed are alternately disposed in one and other faces of the insulating member, and the insulating member is pressingly held in a movable manner by the plug contacts passed through the contact grooves disposed in the one face of the insulating member, and the plug contacts passed through the contact grooves disposed in the other face of the insulating member. According to the configuration, a predetermined gap is ensured between the plug contacts by the insulating member which is not fixed to the plug contacts, so that the plug contacts are prevented from contacting with each other. Therefore, the attachment position and number of the insulating member can be easily changed, and can readily cope with the connecting configuration such as the connecting distance between the boards and the connecting direction thereof. 
   As described above, according to invention, it is possible to provide a connector in which, even when the pitch of contacts of a plug and socket is narrowed and the number of pins is increased, a contact failure between the contacts of the plug and socket due to dust or the like can be suppressed, and insertion and extraction of the plug can be easily performed. 


   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a plan view of a board connector of an embodiment of the invention; 
       FIG. 2  is a side view of the board connector; 
       FIG. 3  is a section view of the board connector taken along the line A—A in  FIG. 1 ; 
       FIG. 4  is a section view of the board connector taken along the line B—B in  FIG. 1 ; 
       FIG. 5(A)  is a side view of a plug contact in which a linear portion has a high-level intermediate portion, and  FIG. 5(B)  is a side view of a plug contact in which a linear portion has a low-level intermediate portion; 
       FIG. 6(A)  is an external view of an inner face side of a cover member, and  FIG. 6(B)  is an external view of an outer face side of the cover member; 
       FIG. 7  is a section view of the board connector showing a plug insertion starting state in fitting of a plug and a socket; 
       FIG. 8  is a section view of the board connector showing a plug insertion intermediate state in fitting of the plug and the socket; 
       FIG. 9  is a section view of the board connector showing a fitting state of the plug and the socket (plug insertion completed state); 
       FIG. 10  is a side view of the board connector showing the fitting state of the plug and the socket; and 
       FIG. 11  is a section view of the board connector showing a state where the plug is pulled up in a plug fitting recess of the socket with using the cover member as a lever in extraction of the plug. 
   


   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Hereinafter, a board connector of an embodiment of the invention will be described with reference to the accompanying drawings. As shown in  FIGS. 1 to 4 , the board connector  1  is used for electrically connecting a board (PCB)  2 A and another board (PCB)  2 B which are juxtaposed, and configured by: a board connector  6 A which is configured by adding a cover member  5 A to a pair of a plug  3 A and a socket  4 A; another board connector  6 B which is configured by adding another cover member  5 B to a pair of a plug  3 B and a socket  4 B; and an insulating member  7 . 
   In the plug  3 A, plural thin contact grooves  31  are disposed in parallel at predetermined intervals (regular intervals) in the right and left or lateral direction in a plug body  30  which is made of an insulating material (synthetic resin), and which has an approximately rectangular parallelepiped shape that is laterally elongated. One-end sides  11 A of plug contacts  10  which are configured by plural thin plate-like conductors, and which are easily bent or bendable are fitted into the contact grooves  31  from the side of the lower end (insertion side end) of the plug body  30 . The one-end sides  11 A are bent into a substantially U-like shape along the longitudinal direction of the plug contacts. In the plug contacts  10 , outer-side pieces elongating from lower-end bent portions of the one-end sides  11 A are pressingly inserted into and fixed to the respective contact grooves  31  so as to be substantially flush with the rear side face of the plug body  30 , and inner-side pieces elongating from lower-end bent portions of the one-end sides  11 A are fitted into the contact grooves  31  in an elastically deformable manner in the front side of the plug body  30 , so that the one-end sides  11 A of the plug contacts  10  are fixed in an insulated state in parallel at predetermined intervals (regular intervals) in the right and left or lateral direction. On the rear side face of the plug  3 A, therefore, the outer-side pieces elongating from the lower-end bent portions of the one-end sides  11 A are exposed in a substantially flush manner, and, from an upper portion of the front side face of the plug  3 A, the plug contacts  10  are drawn out. In order to attach the cover member  5 A to the plug  3 A, a horizontal laterally-directed fulcrum shaft  32  which is perpendicularly projected from upper portions of the right and left side faces of the plug body  30  is integrally disposed. 
   In the socket  4 A, a plug fitting recess  41  into which the plug  3 A is inserted from the upper face side and fitted is disposed in a front portion of a socket body  40  which is made of an insulating material (synthetic resin), and which has an approximately rectangular parallelepiped shape that is laterally elongated. Plural thin contact grooves  42  in which the lower ends are opened in the bottom face of the socket body  40 , and which communicate with the plug fitting recess  41  with breaking a partition wall with respect to the plug fitting recess  41  are disposed in parallel at predetermined intervals (regular intervals) in the right and left or lateral direction in a rear portion of the socket body  40 . Plural legged socket contacts  20  which are configured by plural thin plate-like conductors, and which are bent into a substantially inverted U-like shape along the longitudinal direction are fitted into the contact grooves  42  from the bottom face side of the socket body  40 . In the socket contacts  20 , rear side pieces elongating from upper-end bent portions are pressingly inserted into and fixed to the respective contact grooves  42  so as to elongate along the rear wall faces of the contact grooves  42 , and front side pieces elongating from the upper-bent portions, i.e., movable contact pieces  21  which are disposed in one-end sides of the socket contacts  20 , and which are elastically displaceable are fitted into the contact grooves  42  in an elastically deformable manner. Tip end portions (free-end portions) of the movable contact pieces  21  are projected in the plug fitting recess  41 . In a state where leg portions which are horizontally rearward extended from lower ends of the rear side pieces with respect to the upper-end bent portions of the socket contacts  20 , i.e., soldering portions  22  which are disposed in the other-end sides of the socket contacts  20  are projected in the rear outer side of the socket body  40  so as to be substantially flush with the bottom face of the socket body  40 , the socket contacts  20  are fixed in an insulated state in parallel at predetermined intervals (regular intervals) in the right and left or lateral direction. Thin groove holes  43  are disposed in a front portion of the socket body  40  and in right and left outer sides of the plug fitting recess  41 . One piece of a reinforcing terminal  44  which is an L-like metal part is pressingly inserted into and fixed to each of the groove holes  43  from the side of the bottom face of the socket body  40 , and the other piece of the reinforcing terminal  44 , i.e., a soldering portion (leg portion) is projected to each of the right and left outer sides of the socket body  40  so as to be substantially flush with the bottom face of the socket body  40 . Therefore, a plug insertion port (the open end of the plug fitting recess  41 ) is opened in a front portion of the upper face of the socket  4 A, and the soldering portions  22  of the socket contacts  20  and the soldering portions of the reinforcing terminals  44  are exposed on the bottom face of the socket  4 A so as to be substantially flush with each other. The soldering portions  22  of the socket contacts  20  are projected to the rear outer side of the socket  4 A, and the soldering portions of the reinforcing terminals  44  are projected to the right and left outer sides of the socket  4 A. In order to fix the cover member  5 A when the plug  3 A and the socket  4 A are fitted to each other, engagement claws  45  are integrally disposed in right and left or two places of the rear side face of the socket body  40 . 
   The socket  4 A is surface-mounted on the board  2 A, whereby the soldering portions  22  of the socket contacts  20  and the soldering portions of the reinforcing terminals  44  are fixed by soldering to the board  2 A, and the socket contacts  20  are electrically connected to the board  2 A. In the socket  4 A, positioning protrusions  47  are integrally disposed in two places of the bottom face of the socket body  40  in order to fit the socket to positioning holes  60  disposed in the board  2 A and position the socket with respect to the board  2 A. 
   The cover member  5 A is a molded piece made of an insulating material (synthetic resin), and covers the plug  3 A and the socket  4 A in the fitting state from the upper and rear sides. As shown in  FIG. 6  also, in the cover member  5 A, the following components are integrally disposed: a rectangular plate-like cover top plate portion  50  which covers the plug  3 A and the socket  4 A in the fitting state from the upper side; a rectangular plate-like cover rear side plate portion  51  which is perpendicularly continuous to the rear edge of the cover top plate portion  50 , which covers the plug  3 A and the socket  4 A in the fitting state from the rear side, and which covers the soldering portions  22  of the socket contacts  20  from the upper side; and cover right and left side plate portions  52  which are perpendicularly bent so as to extend along the right and left side edges of the cover top plate portion  50  and those of the cover rear side plate portion  51 , which are projected from a front portion of the upper side face of the socket  4 A into which the plug  3 A is fitted, and which laterally integrally cover rear portions of the right and left side faces of the socket  4 A from upper portions of the right and left side faces of the plug  3 A. In the cover member  5 A, front portions of the right and left side plate portions  52  are pivotally supported via mounting holes  53  by the fulcrum shaft  32  which is disposed on the plug  3 A. The cover member  5 A is swingably attached to the plug  3 A via the fulcrum shaft  32 . The plug  3 A is set by the cover member  5 A to a state where the upper, rear, and right and left sides are covered, and the front side in the direction of drawing out the plug contacts  10 , and the lower side in the direction of inserting the contacts into the socket  4 A are opened. In the cover member  5 A, a protrusion  54  in which the tip end continuously butts against the upper end face of the plug  3 A in a range from the left end to the right end at a swing position where the cover top plate portion  50  is perpendicular to the plug  3 A is integrally disposed on the inner face of the cover top plate portion  50 , and engagement claws  55  which, when the plug  3 A and the socket  4 A are fitted to each other, are engaged in the plug extraction direction with the engagement claws  45  disposed on the socket body  40  to fix the cover member  5 A to the socket  4 A are integrally disposed in right and left or two places of the inner face of the cover rear side plate portion  51 . Furthermore, joining portions  46 ,  56  which, when the plug  3 A and the socket  4 A are fitted to each other, are joined to each other in a front side with respect to the fulcrum shaft  32  are disposed in the socket  4 A and the cover member  5 A. When the plug  3 A and the socket  4 A are fitted to each other, front-end portions of the lower end faces of the cover right and left side plate portions  52  are joined to right and left end portions of the upper end face of the front sidewall of the socket body  40 . The right and left end portions of the upper end face of the front sidewall of the socket body  40  are set as the joining portions  46  on the side of the socket  4 A, and the front end portions of the lower end faces of the cover right and left side plate portions  52  are set as the joining portions  56  on the side of the cover member  5 A. 
   In the cover member  5 A, U-like cutaways  57  which are upward opened are formed in right and left or two places of an upper portion of the cover rear side plate portion  51 , right and left side portions of the cutaways  57  are elongated from a rear portion of the cover top plate portion  50 , and movable plate portions  58  which are surrounded by the cutaways  57 , which are configured by parts of the cover rear side plate portion  51  and a part of the cover top plate portion  50 , and which are perpendicularly bent are integrally disposed. In the movable plate portions  58 , operation levers  59  which are projected from and flushly with parts of the cover top plate portion  50  more rearward than parts of the cover rear side plate portion  51  are integrally disposed, and the engagement claws  55  on the side of the cover member  5 A are integrally disposed on the inner faces of lower end portions of parts of the cover rear side plate portion  51  which are free-end portions of the movable plate portions  58 . In order to facilitate elastic deformation, parts of the cover rear side plate portion  51  in the movable plate portions  58  are thinned. 
   As described above, the board connector  6 A is configured as a board connector with a dust-proof cover in which the cover member  5 A is added to the pair of the plug  3 A and the socket  4 A. 
   Next, the other pair of plug  3 B and socket  4 B of the other board connector  6 B, and the cover member  5 B to be added to the plug and the socket have the same structure as the pair of plug  3 A and socket  4 A of the board connector  6 A and the cover member  5 A to be added to the plug and the socket, and the other board connector  6 B is configured as the same board connector with a dust-proof cover as the board connector  6 A. Therefore, the identical components are denoted by the same reference numerals, and there detailed description is omitted. As shown in  FIG. 3 , however, the other plug  3 B of the other board connector  6 B is configured so that other one-end sides  11 B which are bent into a substantially U-like shape along the longitudinal direction of the plug contacts  10  are fixed to the plug body  30  in an insulated state in parallel at predetermined intervals (regular intervals) in the right and left or lateral direction. Furthermore, the other socket  4 B of the other board connector  6 B is surface-mounted on the other board  2 B, whereby the soldering portions  22  of the socket contacts  20  and the soldering portions of the reinforcing terminals  44  are fixed by soldering to the board  2 B, and the socket contacts  20  are electrically connected to the board  2 B. 
   Next, a plug insertion method in which, in order to fit the plug  3 A and socket  4 A of the board connector  6 A to each other, the plug  3 A is inserted into the plug fitting recess  41  of the socket  4 A will be described with reference to  FIGS. 7 to 10 . 
   As shown in  FIG. 7 , first, the cover member  5 A which is swingably attached via the fulcrum shaft  32  to the plug  3 A is swung about the fulcrum shaft  32 , and held to a swing position where the cover top plate portion  50  is perpendicular to the plug  3 A and the tip end of the protrusion  54  butts against the upper end face of the plug  3 A. By butting (surface contact) between the tip end of the protrusion  54  and the upper end face of the plug  3 A, the plug  3 A is held to a posture perpendicular to the cover top plate portion  50 . In this state, the cover member  5 A is positioned directly above the socket  4 A mounted on the board  2 A, and the cover member  5 A is lowered to approach the board  2 A, whereby the rear lower end side of the cover member  5 A is fitted from the upper side into the tall rear outer side of the socket  4 A. As result of this fitting, the cover member  5 A and the plug  3 A are positioned with respect to the socket  4 A, and the plug  3 A is positioned directly above the plug fitting recess  41  of the socket  4 A. In this state, the cover member  5 A is further lowered to approach the board  2 A, whereby, while the rear portion of the cover member  5 A is further fitted into the rear outer side of the socket  4 A, the lower end portion of the plug  3 A is fitted into the plug insertion port opened in the low-height front upper face side of the socket  4 A (start of plug insertion). In this state, the cover member  5 A is further lowered to approach the board  2 A, whereby, while the rear portion of the cover member  5 A is further fitted into the rear outer side of the socket  4 A as shown in  FIG. 8 , the plug  3 A is inserted into the plug fitting recess  41  of the socket  4 A until the lower-end bent portions of the one-end sides  11 A of the plug contacts  10  hit the tip end portions of the movable contact pieces  21  of the socket contacts  20  which are projected in the plug fitting recess  41  of the socket  4 A. In the subsequent insertion, the movable contact pieces  21  of the socket contacts  20  produce an insertion resistance against the plug  3 A. When the cover member  5 A is pressed down to cause the protrusion  54  of the cover top plate portion  50  to press down the plug  3 A, therefore, the rear portion of the cover member  5 A presses the movable contact pieces  21  of the socket contacts  20  to cause the contacts to be elastically deformed, while the rear portion of the cover member  5 A is further fitted into the rear outer side of the socket  4 A, and the tip end portions of the movable contact pieces  21  are pressed back from the plug fitting recess  41  into the contact grooves  42 . When the plug  3 A passes beyond the tip end portions of the movable contact pieces  21  to be further inserted into the plug fitting recess  41  of the socket  4 A, the tip end portions of the movable contact pieces  21  of the socket contacts  20  are pressed against and contacted with the outer-side pieces elongating from the lower-end bent portions of the one-end sides  11 A of the plug contacts  10  which are exposed on the rear side face of the plug  3 A so as to be substantially flush with each other. In this state, the cover member  5 A is further pressed down, and the plug  3 A is pressed down by the protrusion  54  of the cover top plate portion  50 . As a result, as shown in  FIGS. 9 and 10 , while the rear portion of the cover member  5 A is further fitted into the rear outer side of the socket  4 A, the plug  3 A is completely inserted into the plug fitting recess  41  of the socket  4 A until the lower end of the plug  3 A bumps against the bottom face of the plug fitting recess  41  of the socket  4 A, whereby the plug  3 A and the socket  4 A are fitted together (completion of the plug insertion). 
   During fitting of the plug  3 A and the socket  4 A (when the plug  3 A and the socket  4 A are to be fitted to each other), the plug  3 A is hidden by the cover member  5 A. Since the positioning of the plug  3 A with respect to the socket  4 A can be performed by the cover member  5 A, however, it is not difficult to insert the plug  3 A. 
   As the number of contacts of the plug contacts  10  and socket contacts  20  is more increased because of multiplication of the number of pins of the board connector  6 A, the insertion resistance on the plug  3 A in fitting of the plug  3 A and the socket  4 A becomes higher. The protrusion  54  disposed on the cover top plate portion  50  of the cover member  5 A continuously butts against the upper end face of the plug  3 A in the range from the left end to the right end to press the plug  3 A in the insertion direction, and hence the force of inserting the plug can be evenly transmitted by the cover member  5 A to the whole plug  3 A. Even when the number of contacts is increased as a result of multiplication of the number of pins, therefore, insertion of the plug  3 A can be easily performed. In the embodiment, the protrusion  54  is disposed on the side of the cover member  5 A. Alternatively, the protrusion may be disposed on the side of the plug  3 A. 
   As shown in  FIGS. 1 to 3 ,  9 , and  10 , from the timing just before the fitting of the plug  3 A and the socket  4 A, the engagement claws  55  disposed on the movable plate portions  58  of the cover member  5 A ride on the engagement claws  45  disposed on the socket  4 A while producing elastic deformation of the movable plate portions  58 , the engagement claws  55  disposed on the movable plate portions  58  of the cover member  5 A pass beyond the engagement claws  45  disposed on the socket  4 A to enter below the claws when the plug  3 A and the socket  4 A are fitted together, and at the same time the engagement claws  55  disposed on the movable plate portions  58  of the cover member  5 A are engaged with the engagement claws  45  disposed on the socket  4 A in the plug extraction direction by an elastic return of the movable plate portions  58 . Therefore, the cover member  5 A is fixed (locked) to the socket  4 A, the plug  3 A is fixed (locked) to the socket  4 A by the fixed cover member  5 A, and the fitting states of the plug  3 A and the socket  4 A, and the cover member  5 A and the socket  4 A are held. As a result, in the plug fitting recess  41  of the socket  4 A, the contact between the outer-side pieces elongating from the lower-end bent portions of the one-end sides  11 A of the plug contacts  10 , and the tip end portions of the movable contact pieces  21  of the socket contacts  20  is held, and the one-end sides  11 A of the plug contacts  10  are electrically connected to the board  2 A. 
   When the plug  3 A and the socket  4 A are fitted together, the plug  3 A and the socket  4 A in the fitting state are covered from the upper and rear sides by the cover member  5 A fixed to the socket  4 A, and contact portions of the plug  3 A and socket  4 A in the fitting state, i.e., the plug fitting recess  41  of the socket  4 A is covered to cause dust and the like to hardly enter the plug fitting recess  41 . Therefore, occurrence of a contact failure between the contacts  10 ,  20  of the plug  3 A and socket  4 A because of a narrowed pitch of the contacts  10 ,  20  can be suppressed. Furthermore, the soldering portions  22  of the socket contacts  20  are covered from the upper side by the cover member  5 A, so that dust and the like hardly fall and deposit on the surfaces of the soldering portions  22  and gaps therebetween. Therefore, an insulation failure in the soldering portions  22  of the socket contacts  20  because of a narrowed pitch of the contacts  10 ,  20  of the plug  3 A and socket  4 A can be suppressed. 
   When the plug  3 A and the socket  4 A are fitted together, the joining portions  46  on the side of the socket  4 A, and joining portions  56  on the side of the cover member  5 A which are disposed in the front side with respect to the fulcrum shaft  32  are joined to each other. Namely, the right and left end portions of the upper end face of the front sidewall of the socket body  40  are joined to the front-end portions of the lower end faces of the cover right and left side plate portions  52 . 
   A plug insertion method in which, in order to fit the plug  3 B and socket  4 B of the other board connector  6 B to each other, the plug  3 B is inserted into the plug fitting recess  41  of the socket  4 B, and a fitting state of the plug  3 B and the socket  4 B are identical with the plug insertion method of the board connector  6 A and the fitting state of the plug  3 A and the socket  4 A shown in  FIGS. 7 to 10 . Therefore, their detailed description and corresponding drawings are omitted. 
   As shown in  FIGS. 1 to 3 , in the board connector  6 A, the plug  3 A is inserted and fitted into the plug fitting recess  41  of the socket  4 A, and, in the plug fitting recess  41  of the socket  4 A, and the outer-side pieces elongating from the lower-end bent portions of the one-end sides  11 A of the plug contacts  10 , and the tip end portions of the movable contact pieces  21  of the socket contacts  20  are contacted and held to each other, thereby electrically connecting the one-end sides  11 A of the plug contacts  10  to the board  2 A. By contrast, in the other board connector  6 B, the other plug  3 B is inserted and fitted into the plug fitting recess  41  of the other socket  4 B, and, in the plug fitting recess  41  of the socket  4 B, and the outer-side pieces elongating from the lower-end bent portions of the other-end sides  11 B of the plug contacts  10 , and the tip end portions of the movable contact pieces  21  of the socket contacts  20  are contacted and held to each other, thereby electrically connecting the other-end sides  11 B of the plug contacts  10  to the board  2 B. Therefore, the board  2 A and the other board  2 B can be electrically connected together via the plug contacts  10 , the socket contacts  20  of the socket  4 A, and the socket contacts  20  of the other socket  4 B. 
   Next, a plug extraction method in which, in order to separate from each other the plug  3 A and socket  4 A of the board connector  6 A in the fitting state shown in  FIGS. 1 to 3 ,  9 , and  10 , the plug  3 A is extracted from the plug fitting recess  41  of the socket  4 A will be described with reference to  FIG. 11 . 
   First, in the board connector  6 A in the fitting state shown in  FIGS. 1 to 3 ,  9 , and  10 , an operation of lifting up a rear portion of the cover member  5 A is performed by engaging the fingers with the operation levers  59  disposed on the movable plate portions  58  of the cover member  5 A. When the rear portion of the cover member  5 A is lifted up in this way, the engagement claws  55  disposed on the movable plate portions  58  of the cover member  5 A separate from the rear side face of the socket body  40  while producing elastic deformation of the movable plate portions  58 , and the engagement with the engagement claws  45  disposed on the socket  4 A is canceled. In this state, as shown in  FIG. 11 , the cover member  5 A is swung with setting as a lever fulcrum the joining portions  46 ,  56  joined to each other in the front side with respect to the fulcrum shaft  32  by which the cover member  5 A is swingably attached to the plug  3 A. In accordance with the swinging operation of the cover member  5 A, the plug  3 A is pulled up in the plug fitting recess  41  of the socket  4 A via the fulcrum shaft  32  (with setting the fulcrum shaft  32  as a point of action). Namely, the plug  3 A can be pulled up in the plug fitting recess  41  of the socket  4 A with using the cover member  5 A as a lever. By the operation of pulling up the plug  3 A, the plug  3 A is pulled up in the plug fitting recess  41  of the socket  4 A by the degree at which the lower end portion of the plug  3 A is lifted up to the vicinity of the tip end portions of the movable contact pieces  21  of the socket contacts  20 . Then, the cover member  5 A is lifted up substantially directly above the socket  4 A, whereby the plug  3 A is extracted away from the plug fitting recess  41  of the socket  4 A. 
   In the process of pulling up the plug  3 A in the plug fitting recess  41  of the socket  4 A, in an initial stage of the extraction in which the tip end portions of the movable contact pieces  21  of the socket contacts  20  are in contact with the outer-side pieces elongating from the lower-end bent portions of the one-end sides  11 A of the plug contacts  10 , the contact pressure functions as a large pulling resistance on the plug  3 A. When the lower end portion of the plug  3 A is lifted up to the vicinity of the tip end portions of the movable contact pieces  21  of the socket contacts  20 , the tip end portions of the movable contact pieces  21  of the socket contacts  20  are contacted with the lower-end bent portions of the one-end sides  11 A of the plug contacts  10 . At this timing, the contact pressure (the pulling resistance on the plug  3 A) is reduced. As the contact pressure is further reduced when the lower end portion of the plug  3 A passes beyond the tip end portions of the movable contact pieces  21  of the socket contacts  20  and the one-end sides  11 A of the plug contacts  10  separate from the tip end portions of the movable contact pieces  21  of the socket contacts  20 , the pulling resistance on the plug  3 A is further substantially eliminated. When, as described above, the plug  3 A is pulled up with using the cover member  5 A as a lever in the plug fitting recess  41  of the socket  4 A by the degree at which the lower end portion of the plug  3 A is lifted up to the vicinity of the tip end portions of the movable contact pieces  21  of the socket contacts  20 , the pulling and extraction of the plug  3 A in the plug fitting recess  41  of the socket  4 A can be easily performed with applying a small force. 
   As the number of contacts of the plug contacts  10  and socket contacts  20  is increased as a result of multiplication of the number of pins of the board connector  6 A, the pulling resistance on the plug  3 A is larger in extraction of the plug  3 A fitted to the socket  4 A. Since the plug  3 A can be pulled up by a small force with using the cover member  5 A as a lever in the plug fitting recess  41  of the socket  4 A, however, extraction of the plug  3 A can be easily performed even when the number of contacts is increased as a result of multiplication of the number of pins. 
   A plug extraction method in which, in order to separate the plug  3 B and socket  4 B of the other board connector  6 B in the fitting state shown in  FIGS. 1 to 3  from each other, the plug  3 B is extracted from the plug fitting recess  41  of the socket  4 B is identical with the plug extraction method of the board connector  6 A shown in  FIG. 11 . Therefore, its detailed description and corresponding drawings are omitted. 
   The socket contacts  20  which are configured by plural thin plate-like conductors are formed in parallel into a state where end portions of the soldering portions  22  are continuous to a carrier (not shown) with forming predetermined intervals at predetermined pitches therebetween, by punching and bending a thin conductive metal plate. In this state, the socket contacts  20  are fitted into the contact grooves  42  of the socket body  40 , and fixed to the socket body  40  in parallel in an insulated state with forming predetermined intervals (regular intervals) in the right and left or lateral direction, and then the carrier is separated from the socket contacts  20 , thereby configuring the sockets  4 A,  4 B. The plug contacts  10  which are configured by plural thin plate-like conductors, and which are easily bent or bendable are formed in parallel into a state where end portions of the one-end sides  11 A are continuous to a carrier (not shown), and end portions of the other-end sides  11 B are continuous to another carrier (not shown), by punching and bending a thin conductive metal plate with disposing predetermined intervals at predetermined pitches between the carrier and the other carrier. In this state, the one-end sides  11 A of the plug contacts  10  are fitted into the contact grooves  31  of the plug body  30 , the one-end sides  11 A of the plug contacts  10  are fixed to the plug body  30  in an insulated state in parallel at predetermined intervals (regular intervals) in the right and left or lateral direction, and then the carrier is separated from the one-end sides  11 A of the plug contacts  10 , thereby configuring the plug  3 A. By contrast, the other-end sides  11 B of the plug contacts  10  are fitted into the contact grooves  31  of the plug body  30 , the other-end sides  11 B of the plug contacts  10  are fixed to the plug body  30  in an insulated state in parallel at predetermined intervals (regular intervals) in the right and left or lateral direction, and then the carrier is separated from the other-end sides  11 B of the plug contacts  10 , thereby configuring the other plug  3 B. 
   As shown in  FIGS. 1 to 3 , and  5 , in the plug contacts  10  through which the plug  3 A is linked with the other plug  3 B, intermediate portions  12 ,  13  (between the one-end sides  11 A and the other-end sides  11 B) between the plug  3 A and the other plug  3 B are formed into a linear shape so as to elongate in parallel to the boards  2 A,  2 B, except their both end portions. The both end portions are formed into an inclined state which is upward inclined toward the respective end portions. The lengths of the linear portions of the intermediate portions  12 ,  13  are set on the basis of the distance between the board  2 A and other board  2 B which are placed in parallel to each other, i.e., the connecting distance. One-end side inclined upper ends of the intermediate portions  12 ,  13 , and upper end portions of the inner-side pieces elongating from the lower-end bent portions of the one-end sides  11 A are continuously integrally linked with each other, and other-end side inclined upper ends of the intermediate portions  12 ,  13 , and upper end portions of the inner-side pieces elongating from the lower-end bent portions of the other-end sides  11 B are continuously integrally linked with each other. The plug contacts  10  are formed so as to be symmetrical about a point where the length of the linear portion of the intermediate portion  12  or  13  is bisected. 
   As shown in  FIGS. 2 ,  3 , and  7  to  10 , the inclined portions of the both end portions of the intermediate portions  12 ,  13  of the plug contacts  10  are drawn out obliquely downward from the front side faces of the plugs  3 A,  3 B. As shown in  FIG. 11 , therefore, the front portions of the cover members  5 A,  5 B which are lowered by the swing of the cover members  5 A,  5 B in pulling of the plugs  3 A,  3 B in the plug fitting recesses  41  of the sockets  4 A,  4 B with setting the cover members  5 A,  5 B as a fulcrum do not interfere with the plug contacts  10  drawn out from the front side faces of the plugs  3 A,  3 B, and hence it is possible to prevent the plug contacts  10  from being bent and damaged. 
   As shown in  FIGS. 1 to 5 , the plug contacts  10  are formed into two kinds in which only the level positions of the linear portions are differentiated by changing the lengths of the inclined portions of the both end portions in the intermediate portions  12 ,  13 . The plug contacts  10  having the intermediate portion  12  in which the level of the linear portion is high, those having the intermediate portion  13  in which the level of the linear portion is low are alternately arranged. Therefore, the linear portions of the intermediate portions  12 ,  13  of the plug contacts  10  are positionally shifted from each other in the thickness direction (the vertical direction) of the contacts, so that predetermined gaps  14  in a side view are ensured in the linear portions of the intermediate portions  12 ,  13  of the plug contacts  10 . The both ends of the gaps  14  are closed by the inclined portions of the both end portions of the intermediate portions  13  in which the level of the linear portion is low. 
   As shown in  FIGS. 1 to 4 , an insulating member  7  is disposed in the intermediate portions  12 ,  13  of the plug contacts  10  between the plug  3 A and the other plug  3 B. A predetermined gap is ensured between the adjacent plug contacts  10  by the insulating member  7 , so that the plug contacts are prevented from contacting with each other. The insulating member  7  is made of an insulating material (synthetic resin), and has an approximately rectangular parallelepiped shape that is laterally elongated. Plural thin contact grooves  70  through which the intermediate portions  12 ,  13  of the plug contacts  10  are to be passed at a predetermined pitch with forming predetermined intervals are alternately distributively disposed in the upper and lower faces of the insulating member  7 . The linear portions of the intermediate portions  12  of the plug contacts  10  having the intermediate portion  12  in which the level of the linear portion is high are fitted from the upper face side into and passed in the anteroposterior direction through the contact grooves  70  disposed in the upper face of the insulating member  7 , and those of the intermediate portions  13  of the plug contacts  10  having the intermediate portion  13  in which the level of the linear portion is low are fitted from the lower face side into and passed in the anteroposterior direction through the contact grooves  70  disposed in the lower face of the insulating member  7 . A plate-like core part  71  that is the insulating member  7  the thickness of which is reduced by the contact grooves  70  is interposed in the thickness direction (the vertical direction) of the core part between the linear portions of the intermediate portions  12  of the plug contacts  10  having the intermediate portion  12  in which the level of the linear portion is high, and those of the intermediate portions  13  of the plug contacts  10  having the intermediate portion  13  in which the level of the linear portion is low, and the insulating member  7  is interposed between the intermediate portions  12 ,  13  of the plug contacts  10  so as to be movable in the contact length direction, whereby a predetermined gap is ensured between the adjacent plug contacts  10  by partition walls  72  which are the insulating member  7  between the contact grooves  70 , so that the plug contacts are prevented from contacting with each other. 
   The adjacent plug contacts  10  are prevented: from contacting with each other by the insulating member  7  which is simply interposed between the intermediate portions  12 ,  13  of the plug contacts  10  so as to be movable in the contact length direction, and which is not fixed. Therefore, the attachment position and number of the insulating member  7  can be easily changed, and can readily cope with the connecting configuration such as the connecting distance between the boards  2 A,  2 B and the connecting direction thereof. The predetermined gaps  14  in a side view are ensured from the beginning between the linear portions of the intermediate portions  12  of the plug contacts  10  which are passed through the contact grooves  70  disposed in the upper face of the insulating member  7 , and those of the intermediate portions  13  of the plug contacts  10  which are passed through the contact grooves  70  disposed in the lower face of the insulating member  7 . Therefore, interposing of the insulating member  7  can be easily performed. When the attachment position or number of the insulating member  7  is changed, furthermore, a deforming force is not applied to the plug contacts  10 , and hence plastic deformation can be prevented from occurring. 
   In the embodiment, the board connector  1  used for electrically connecting the board  2 A and other board  2 B which are placed in parallel has been described. Alternatively, the plug contacts  10  may be bent in the linear portions of the intermediate portions  12 ,  13 , thereby enabling also stepped or angled boards to be connected to each other. The sockets  4 A,  4 B of the surface-mount type have been described. Alternatively, sockets of the pin-mount type may be used.
The present invention relates to a board connector for electrically connecting together circuit boards which are incorporated in, for example, a mobile telephone. A dust-proof measure is carried out by swingably attaching a cover member to a plug via a fulcrum shaft, and covering contact portions of the plug and socket in a fitting state with the cover member. In one of the plug and the cover member, a protrusion which causes an end portion to continuously butt against another one of the plug and the cover member from one end to another end is disposed, whereby, when the plug is inserted, the force of inserting the plug is evenly transmitted from the cover member to the whole plug. Joining portions which, when the plug and the socket are fitted to each other, are joined to each other in a front side with respect to the fulcrum shaft are disposed in the socket and the cover member. The plug is pulled up with using the cover member as a lever by swinging the cover member with setting the joining portions as a lever fulcrum.