Abstract:
A board connector for fixing a printed circuit board on which a conductor circuit is formed includes a first connector housing, a second connector housing, an operating lever and an auxiliary lever. The first connector housing, accommodating a plurality of first terminals therein. The second connector housing, accommodating a plurality of second terminals therein, and provided above the first connector housing. The operating lever, pivotably coupled to the first connector housing and the second housing for moving the first connector housing and the second connector to closer each other between a first position and a second position. The auxiliary lever, pivotably coupled to the operating lever and the first connector housing for restricting the pivotal range of the operating lever. The first connector housing and the second connector housing have a space for inserting end portions of the printed circuit board therebetween when the operation lever is located in the first position. The printed circuit board is secured between the first connector housing and the second connector housing when the operation lever is located in the second position.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    The present invention relates to a board connector contained in an electric connection box and fixed to a wiring board forming an internal circuit of the electric connection box with zero insertion force.  
           [0002]    Heretofore, junction boxes and electric connection boxes are employed for supplying power to electric equipment, exchange signals among electronic parts and make internal circuits branch off intensively around automotive engine rooms and instrument panels.  
           [0003]    In some electric connection box, there are installed a printed circuit board mounted with a fuse, a relay, a connector or the like and a wiring board with a conductor circuit forming an internal circuit formed thereon, whereas the junction box is equipped with the wiring board and a board connector connected to the wiring board. However, as the term ‘junction box’ may be used to collectively mean a junction box inclusive of an electric connection box sometime, the term ‘electric connection box’ is used to collectively mean such an electric connection box in this specification.  
           [0004]    The electric connection box contains one sheet of wiring board or a plurality of laminated wiring boards formed with conductor circuits, the number of which depends on the kind or specification of the vehicle. A board connector is connected to the edge portion or onto the surface of the wiring board so as to supply power to electric equipment or exchange signals between electronic parts.  
           [0005]    [0005]FIG. 7 shows the art related to a board connector of the sort stated in JP-A 9-82427. A board connector  80  includes a connector housing  81 , first and second terminals  85  and  86  contained in the connector housing  81 , and a lever  87 . The connector housing  81  includes a board portion  82  and a side wall portion  84  provided on both sides of the board portion  82  with the upper portion of the board portion  82  open. Further, a number of slits  83   a  and  83   b  respectively cut out from both the front and back are formed in the board portion  82 .  
           [0006]    The first and second terminals  85  and  86  are long enough not to more or less overlap each other in the width direction of the connector housing  81  with the terminals  85  and  86  incorporated therein, whereby the positions of the adjoining first and second terminals  85  and  86  are arranged alternately in the longitudinal and width directions of the connector housing  81 .  
           [0007]    The lever  87  is pivotably supported above the connector housing  81  and by pivoting the lever  87  in the horizontal direction, a wiring board  88  can be press-fixed to the wiring board  88 . More specifically, mating portions (not shown) curved toward the pivotal center of the lever are provided and the mating portions are mated with the front ends of the elastic support pieces (not shown) of the second terminals whereby to support the lever  87  pivotably on the front ends of the elastic support pieces.  
           [0008]    Further, protrusions  87   a  are provided on the front-end side faces of the lever  87  and when the lever is pivoted in the horizontal direction, the protrusions  87   a  are fitted in the respective depressions  84   a  of the side wall portions  84  of the connector housing  81 , so that the lever  87  is prevented from being easily released.  
           [0009]    Many terminal portions (not shown) electrically contacting the board connector  80  are provided in longitudinally two rows on the back of the wiring board  88  and when the terminal portions in the front row are brought into contact with the contacts  86   a  of the second terminals  86 , the terminal portions in the back row are brought into contact with the contacts  85   a  of the first terminals.  
           [0010]    With the arrangement above, as the high-density arrangement of the terminals  85  and  86  is possible, the pitch of the adjoining terminals  85  and  86  is narrowed, so that the size of the connector becomes reducible.  
           [0011]    However, there are following problems to be solved in the case of the related board connector.  
           [0012]    Recently, with an increase in the number of electric devices and electronic parts to be loaded in automobiles, spaces available for installation of these electric and electronic components around engine rooms and instrument panels tend to become smaller, whereupon it is requested to make electric connection boxes smaller in size. On the other hand, the number of signal lines for exchanging signals among electronic parts is on the increase and there develops a demand for high-density conductor circuits and multi-pole board connectors.  
           [0013]    The related board connector  80  described above is intended to narrow the pitch of the terminals  85  and  86  by arranging the adjoining terminals  85  and  86  in longitudinally two planar rows. However, the board connector  80  is applicable to only the single-sided wiring board but not so structured as to be applicable to a wiring board having a terminal portion formed on both sides of the board.  
           [0014]    Further, the board connector  80  is not applicable to the wiring board  88  having the terminal portion formed on both sides of the board because it is to be fixed to one end edge portion of the wiring board  88 . More specifically, the wiring conductors forming the conductor circuit are also not applicable to the wiring board for forming the terminal portions by drawing out the wiring conductors to both the adjoining portions of the wiring board.  
           [0015]    Moreover, though the wiring board  88  is press-fixed to the board connector  80  by pivoting the lever  87  of the board connector  80 , there is the possibility of letting the wiring board  88  slip out of the board connector  80  in case where tensile force inadvertently acts on the wiring board  88 .  
         SUMMARY OF THE INVENTION  
         [0016]    It is therefore an object of the present invention to provide a board connector which is applicable to a wiring board formed with a conductor circuit formed on both sides of the wiring board to ensure that terminals are multi-polarized with their highly reliable electrical connections to the wiring board and is joined to the wiring board with zero insertion force.  
           [0017]    In order to achieve the above object, according to the present invention, there is provided a board connector for fixing a printed circuit board on which a conductor circuit is formed, comprising:  
           [0018]    a first connector housing, accommodating a plurality of first terminals therein;  
           [0019]    a second connector housing, accommodating a plurality of second terminals therein, and provided above the first connector housing;  
           [0020]    an operating lever, pivotably coupled to the first connector housing and the second housing for moving the first connector housing and the second connector to closer each other between a first position and a second position; and  
           [0021]    an auxiliary lever, pivotably coupled to the operating lever and the first connector housing for restricting the pivotal range of the operating lever;  
           [0022]    wherein the first connector housing and the second connector housing have a space for inserting end portions of the printed circuit board therebetween when the operation lever is located in the first position; and  
           [0023]    wherein the printed circuit board is secured between the first connector housing and the second connector housing when the operation lever is located in the second position.  
           [0024]    In the above configuration, the connector housing is divided into first housing and the second housing and both the housings are coupled to the operating lever. Thus, the print circuit board is fitted in between both the housing with zero insertion force without rubbing against both the housings and held between both the housing by pivoting the operating lever. As the first housing is provided with the auxiliary lever, the operating lever is supported by the auxiliary lever and the pivotal angle of the operating lever is controllable. Therefore, the printed circuit board can be fitted in the board connector with zero insertion force, so that the terminal portions and the like can be prevented from being deformed and damaged. Moreover, the operability of the operating lever is improved, whereby the printed circuit board and the board connector can easily be combined together.  
           [0025]    Preferably, the operating lever includes an operating portion and a pair of arms extended from both ends of the operating portion, and each arm has coupling portions pivotably coupling to the first connector housing and the second connector housing respectively, and the operating portion has a plug-in portion slidably coupled to the auxiliary lever.  
           [0026]    In the above configuration, the operating portion is provided with the plug-in portion slidably coupled to the auxiliary lever and the arms are provided with the coupling portions coupled to the connector housing, whereby the operating lever and the auxiliary lever are smoothly operated and the pivoting of the operating lever is controllable. Moreover, both the housings are moved in a manner interlocking with the pivoting of the arms so as to move both the housing closer to each other. Therefore, the operability of the operating lever is improved and the printed circuit board can be fitted in the board connector with zero insertion force.  
           [0027]    Preferably, the plug-in portion has a notch and a slide pin provided on an inner face of the notch, and the auxiliary lever has a slot engaged with the slide pin.  
           [0028]    In the above configuration, as the plug-in portion has the notch and the slide pin and the auxiliary lever has the slot mating with the slide pin, the operating lever and the auxiliary lever are slidably coupled and the slide pin is reciprocated in the slot in a manner interlocking with the pivoting of the operating lever. Therefore, the operating lever is pivotably supported by the auxiliary lever and this results in improving the stability of the operation of the operating lever.  
           [0029]    Preferably, a portion near the first connector housing and the second connector housing side of the auxiliary lever is a L shaped portion, and portions near the first connector housing and the second connector housing side of the arms are L shaped portions.  
           [0030]    In the above configurations, the auxiliary lever and the arms are folded and lie on top of another when the operating lever is pushed down so as to fix the board connector to the wiring board. Consequently, the auxiliary lever and the arms are prevented from sticking out and interfering with the outside.  
           [0031]    Preferably, a pair of guiding walls are provided on the second connector housing to restrict a pivotal direction of the auxiliary lever, and the auxiliary lever is positioned between the guiding walls.  
           [0032]    In the above configuration, as the guiding walls for holding the auxiliary lever are provided in the second housing, the second housing and the auxiliary lever are positioned properly as the former and the latter are restricted mutually. Consequently, the positional deviation of the board connector is prevented with respect to the terminals of the printed circuit board, so that the reliability of the electrical connections is improved.  
           [0033]    Preferably, the first terminals are accommodated in a first terminal chambers provided in the first connector housing, and the second terminals are accommodated in a second terminal chambers provided in the second connector housing. The first terminals and second terminals are arranged so as to connected to terminal portions of the conductor circuit, the terminal portions formed on both sides of the printed circuit board when the operation lever is located in the second position.  
           [0034]    In the above configuration, the terminals contained in the terminal chambers are positioned in vertical two rows and electrically connected to the terminal portions formed on both sides of the printed circuit board. It is therefore possible to have the terminals multi-polarized and provide a high-density internal circuit as the multi-polarized terminals are brought into contact with the terminal portions of the printed circuit board with the conductor circuit formed on both sides of the printed circuit board.  
           [0035]    Preferably, latch portions, respectively engaged with engagement portions which are provided on the printed circuit board, are provided on the second connector housing.  
           [0036]    In the above configuration, the engagement portions of the printed circuit board are joined to the latch portions of the housing before being fixed to the insulating board after the wiring board is held by the board connector to ensure that the wiring board is prevented from slipping out. Thus, the reliability of the electrical connections is improved. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0037]    The above objects and advantages of the present invention will become more apparent by describing in detail preferred exemplary embodiments thereof with reference to the accompanying drawings, wherein:  
         [0038]    [0038]FIG. 1 shows a perspective view of a board connector embodying the invention;  
         [0039]    [0039]FIG. 2 shows a perspective view of a condition in which a wiring board is fitted in the board connector shown in FIG. 1;  
         [0040]    [0040]FIG. 3 shows a perspective view of a condition in which the wiring board is removed from the board connector;  
         [0041]    [0041]FIG. 4 shows a sectional view of the vicinity of the central portion when the operating lever of the board connector is raised;  
         [0042]    [0042]FIG. 5 shows a sectional view of the vicinity of the central portion when the operating lever of the board connector is pushed down;  
         [0043]    [0043]FIGS. 6A and 6B shows sectional views of the board connectors: FIG. 6A shows the board connector in a condition before the board connector makes contact with the wiring board and FIG. 6B shows after the board connector makes contact therewith; and  
         [0044]    [0044]FIG. 7 shows a perspective view of an example of a related board connector. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0045]    A detailed description will now be given of an embodiment of the invention with reference to the drawings. FIGS.  1  to  6  show a board connector embodying the invention.  
         [0046]    A board connector  10  shown in FIG. 1 is applied to a printed circuit board (wiring board)  60  with a conductor circuit formed on both the front and back of the printed circuit board and used for exchanging signals between electronic parts.  
         [0047]    The board connector  10  includes a connector housing  11 , a plurality of terminal fittings (terminals)  55  housed in the terminal holding chambers  19  and  31  of the connector housing  11 , an operating lever  35  coupled to the outer walls (wall portions)  16  and  26  of the connector housing  11 , and an auxiliary lever  45  slidably coupled to the operating lever  35 . The connector housing  11 , the operating lever  35  and the auxiliary lever  45  are formed of synthetic resin or the like by injection molding. The terminal fittings  55  (see FIG. 6) are formed of conductive metal and made by punching terminal fittings from a sheet of metal and bending the punched ones.  
         [0048]    The connector housing  11  essentially consists of two vertically divided housings including a fixed-side housing  15  and a movable-side housing  25 . Both housings  15  and  25  are L-shaped in top plan view and formed in well-balanced bilateral symmetry with respect to a dividing line CL 1  passing a corner portion  32 .  
         [0049]    A mating space  13  for receiving the printed circuit board  60  is formed between the fixed-side housing  15  and the movable-side housing  25 . The mating space  13  has an opening greater in dimension than the thickness of the printed circuit board  60  so that the printed circuit board  60  can be fitted in the connector housing  11  with zero insertion force. After the printed circuit board  60  is fitted in the printed circuit board  60 , both housings  15  and  25  are set closer to each other by tilting the operating lever  35  downward as will be described later, whereby the printed circuit board  60  is held therebetween.  
         [0050]    For convenience of explanation, the front and back, the top and bottom of the connector housing  11  are distinguished from one another as follows. The front is the side where the printed circuit board  60  is fitted in and the back is the side where electric wires  78  are drawn out. The operating lever  35  and the auxiliary lever  45  are placed on the upper side, whereas the lower side is opposite thereto. Further, though the lateral direction is the direction in which the operating lever  35  is coupled to the outer walls  16  and  26 , the left side is not to be distinguished from the right side as the connector housing  11  is in lateral symmetry.  
         [0051]    The outer walls  16  and  26  of both housings  15  and  25  have upper and lower walls  16   a ,  16   b ,  26   a  and  26   b , front walls  16   c  and  26   c  joined to the printed circuit board  60 , rear walls  16   d  and  26   d  from which the electric wires  78  connected to the terminal fittings  55  are drawn out and side walls  16   e ,  16   f  (not shown),  26   e  and  26   f  on both sides. The terminal holding chambers  19  and  31  are arranged so as to pass longitudinally through the terminal holding chambers  19  and  31  in both the fixed-side housing  15  and the movable-side housing  25 . A pair of upright walls  28  are formed on the upper wall  26   a  of the movable-side housing  25  and latching walls  30  bent in a direction perpendicular to a extending direction of the upright walls are coupled to the adjoining end portions of the respective upright walls  28 .  
         [0052]    A projected portion (latching portion)  27  (see FIG. 4) mating with each cut portion (mating portion)  69  (see FIG. 3) of the printed circuit board  60  is provided on both sides of the lower wall  26   b  of the movable-side housing  25 . The cut portion  69  is provided in a pair of opposed corner portions  68   c  and  68   d  of the printed circuit board  60 . In this case, the projected portions may be provided on the printed circuit board  60 , whereas the cut portions may be provided in the movable-side housing  25 .  
         [0053]    As the terminal holding chambers  19  and  31  are provided in the respective housings  15  and  25 , the connector housing  11  as a whole is arranged over the terminal holding chambers  19  and  31  in a double deck form. The terminal holding chambers  19  and  31  are separated from each other by a partition wall (not shown) so that the adjoining terminal fittings  55  are prevented from shorting.  
         [0054]    The terminal fittings  55  equal in number to the terminal portions  76  (see FIG. 3) of the printed circuit board  60  are housed in the plurality of terminal holding chambers  19  and  31 . The upper and lower terminal holding chambers  19  and  31  are arranged alternately so as to correspond to the terminal portions  76  of the printed circuit board  60 , whereby the terminal fittings  55  are connected to the terminal portions  76  on a one-to-one footing.  
         [0055]    As shown in FIG. 1, the terminal holding chambers  19  and  31  positioned in bilateral symmetry with the dividing line CL 1  held therebetween are directionally matched. In other words, the terminal holding chambers  19  and  31  are arranged in the same direction. The direction in which the terminal holding chambers  19  and  31  are depend on the dividing line CL 1 , that is, in a 45° direction according to this embodiment of the invention. This is because the board connector  10  according to this embodiment of the invention is applied to the square printed circuit board  60  shown in FIG. 2 or  3  and because the direction of the diagonal line CL 2  of the printed circuit board  60  is equal to the 45° direction. Consequently, the direction in which the terminal holding chambers  19  and  31  are led also changes as the shape of the printed circuit board  60  changes. In case where the printed circuit board  60  is rectangular or parallelogrammic, because the diagonal line CL 2  thereof is not led in the 45° direction, the direction of the terminal holding chambers  19  and  31  may be led in a direction smaller or greater than the 45° direction.  
         [0056]    The pair of upright walls  28  are provided along the dividing line CL 1  in the corner portion  32  of the movable-side housing  25 . The inner wall surface  28   a  of the upright wall  28  is formed on the same plane as the groove wall surface  29  of a slot  29  provided in a depressed condition. In other words, the provision of the pair of upright walls  28  serves to increase the length of the slot  29  in the vertical direction to ensure that the auxiliary lever  45  is restrained by both the walls as will be described later.  
         [0057]    The latching walls  30  are linked with the front end portions of the upright walls  28  and uprightly formed with respect to the dividing line CL 1  and also formed in parallel to the operating portion  36  of the operating lever  35  as will be described later. A pawl portion  30   a  mating with the tapered portion  37  of the operating portion  36  is formed on each latching wall  30  and along the upper end portion of the latching wall  30 , so that the latched condition of the operating lever  35  is prevented from being released by making the pawl portion  30   a  mate with the tapered portion  37  of the operating lever  35 .  
         [0058]    The operating lever  35  essentially consists of a pair of arms  40  extended from both sides of the operating portion  36 , which is a flat plate member extending in a direction perpendicular to the dividing line CL 1 . A plug-in portion  38  for the auxiliary lever  45  is provided in the central portion of the operating portion  36 .  
         [0059]    The plug-in portion  38  has a notch  38   b  and a slide pin  39  projected from the inner walls  38   a  of the notch  38   b  (see FIGS. 4 and 5). A framelike slot  46  formed at the other end of the auxiliary lever  45  is slidably coupled to the slide pin  39 . As the slot  46  of the auxiliary lever  45  is coupled to the slide pin  39 , the operating lever  35  is pivotably supported and the pivotal direction of the operating lever  35  is restricted so that the operability of the operating lever  45  is improved.  
         [0060]    The arms  40  are pivotably coupled to the outer walls  16  and  26  of the connector housing  11  in a diagonal slidable condition via mating holes  40   a  and  40   b . More specifically, the arms  40  are coupled to pins  17  and  33  formed on the side walls  16   e ,  16   f ,  26   e  and  26   f  on both sides of the fixed-side housing  15  and the movable-side housing  25  via the pair of mating holes  40   a  and  40   b . The first pins  17  (only one side is shown) are formed on the side walls  16   e  and  16   f  on both sides of the fixed-side housing  15  and the second pins  33  (only one side is shown) are formed on the side walls  26   e  and  26   f  on both sides of the movable-side housing  25 . The front end side of each arm  40  is curved in L shape so that when the arm  40  is pushed down, the operating portion  36  is put on the top surface of the movable-side housing  25  in parallel.  
         [0061]    [0061]FIG. 4 shows the raised condition of the operating portion  36 , whereas FIG. 5 shows the pushed-down condition of the operating portion  36 . When the arms  40  are pivoted with the first pins  17  as fulcrums, the second pins  33  draw an arcuate pivotal locus with the first pins  17  as reference points and the movable-side housing  25  is moved close to or away from the fixed-side housing  15 . In other words, the arms  40  are made to lie down when the operating portion  36  is pushed down (see FIG. 5) and the movable-side housing  25  is moved closer to the fixed-side housing  15 , so that the mating space  13  between both housings  15  and  25  is narrowed. When the operating portion  36  is raised (see FIG. 4), on the other hand, the arms  40  are also raised and the movable-side housing  25  is moved away from the fixed-side housing  15 , so that the mating space  13  between both housings  15  and  25  is widened.  
         [0062]    As shown in FIG. 4, the auxiliary lever  45  has a mating hole  47  on its one end side, the mating hole  47  being coupled to the third pin  18  of the fixed-side housing  15  in a diagonal slidable condition and the slot  46  slidably coupled to the operating lever  35  on the other end side. The slot  46  of the auxiliary lever  45  is in the form of a frame and the slide pin  39  of the operating portion  36  is fitted and reciprocated in the frame in a manner interlocking with the pivoting of the operating lever  35 . Moreover, a portion of the auxiliary lever  45  on the board coupling side is convexly curved and when the operating lever  35  is pushed down, the auxiliary lever  45  is put on the top surface of the movable-side housing  25  in parallel.  
         [0063]    When the operating lever  35  is raised, the slide pin  39  is brought into contact with one side of the slot  46  and as the operating lever  35  becomes unable to be raised further, the pivoting range of the operating lever  35  is thus restricted. In this condition, the printed circuit board  60  can be fitted in or removed. When the operating lever  35  is pushed down, on the other hand, the slide pin  39  is caused to slide toward the opposite side of the slot  46  whereby to put the auxiliary lever  45  and the operating lever  35  on top of each other. In this condition, the printed circuit board  60  is held between both housings  15  and  25 . The dimensions of the slot  46  are optional and by changing the dimensions thereof, the pivotal angle β (pivotable range) of the operating lever  35  can be varied.  
         [0064]    [0064]FIG. 2 shows a condition in which the printed circuit board  60  has been fitted in the board connector  10 . The printed circuit board  60  is fitted in the mating space  13  (see FIG. 1) between both housings  15  and  25  with zero insertion force and brought into contact with the back wall so that the positioning of the direction of insertion is determined. Then the projected portions  27  are mated with the cut portions  69  of the printed circuit board  60  by pushing down the operating lever  35  and the printed circuit board  60  is vertically held between both housings  15  and  25 . The operating lever  35  is latched onto the pawl portions  30   a  of the latching walls  30  so as to prevent the operating lever  35  from being inadvertently raised. In the fitted condition above, the terminal fittings  55  and the terminal portions  76  remain mutually connected.  
         [0065]    [0065]FIG. 3 shows the board connector  10  in such a condition that the printed circuit board  60  has been removed. When the printed circuit board  60  is removed, it is only needed to reverse the components assembly operation above. More specifically, while the latching walls  30  are being warped so as to release the latched condition of the operating lever  35 , the operating lever  35  is raised so as to release the projected portions  27  from latching the cut portions  69  and the printed circuit board  60  is pulled out, whereupon the removing operation is easily performed.  
         [0066]    As shown in FIG. 6, the terminal fittings  55  with the electric wires  78  are extending in the mating space  13  (see FIG. 3, etc.) between both housings  15  and  25 . The terminal fittings  55  are arranged vertically in the upper and lower terminal holding chambers  19  and  31  so that convexly curved elastic contact portions  57  are opposite to one another. Although the gap between the facing elastic contact portions  57  is set wider than the thickness of the printed circuit board  60  as shown in FIG. 6A, the gap therebetween is narrowed when the operating lever  35  (see FIG. 1, etc.) is pushed down as shown in FIG. 6B and the terminal portions  76  (FIG. 3) on both sides of the printed circuit board  60  rub against the respective upper and lower elastic contact portions  57  and contact one another.  
         [0067]    The terminal fittings  55  are formed by punching terminal fittings from a conductive board and bending the punched ones. An electric-wire connecting portion  56  is formed on one side of each of the terminal fittings  55 , whereas a tab-like front end portion  58  is formed on the other side thereof, the curved elastic contact portion  57  being formed integrally therewith between the electric-wire connecting portion  56  and the tab-like front end portion  58 .  
         [0068]    The electric-wire connecting portion  56  has a conductor caulking portion for caulking a conductor and a covered-wire caulking portion for caulking a covered wire and is formed with a pair of pressure-welding pieces. The elastic contact portion  57  is a contact portion for causing the internal circuit to conduct by contacting the terminal portion  76 , so that suitable contact pressure is maintained by making use of its curved configuration so as to resiliently contact the terminal portion  76 .  
         [0069]    The tab-like front end portions  58  are inserted into the holes (not shown) of the terminal holding chambers  19  and  31  and fixed lest the tab-like front end portions  58  are moved. Mating holes (not shown) are provided in the terminal fittings  55  and by mating with the mating projections (not shown) of the terminal holding chambers  19  and  31 , prevented from rearwardly slipping out. Incidentally, the terminal fittings  55  may be provided with the mating projections and the terminal holding chambers  19  and  31  may be provided with the mating holes.  
         [0070]    The printed circuit board  60  shown in FIGS. 2 and 3 will be provided briefly hereinbelow. The printed circuit board  60  is in the form of a flat rectangular board and formed by printing wiring conductors  75  integrally on an insulating board  65  made of organic material such as epoxy resin or the like. Although the printed circuit board  60  will be described according to this embodiment of the invention, such a circuit board may be formed by insert-molding or bonding thin wiring conductors  75  on the insulating board  65 . Moreover, conductive resin material may be applicable to the wiring conductors  75 .  
         [0071]    The printed circuit board  60  is a so-called double sided printed circuit board having a conductor circuit on both sides. In comparison with a single-sided printed circuit board, not only is the number of wiring conductors on the double sided printed circuit board doubled but also complicated wiring that needs cross wiring is easily formable.  
         [0072]    The printed conductor circuit is formed with the parallel wiring conductors  75  arranged regularly with a predetermined pitch. Due to the fact that a very small current for a signal of a several-millimeter ampere flows through the wiring conductors  75 , it is unlikely that the wiring conductors  75  are broken by fusion.  
         [0073]    The conductor circuit is printed on both sides of the printed circuit board so that the two circuits are made solidly alternate with each other. The conductor circuit on the surface side forms a conductor circuit in the line direction, whereas the conductor circuit on the undersurface side forms a conductor circuit in the column direction. In other words, the wiring conductors  75  forming both the conductor circuits are subjected to solidly cross wiring.  
         [0074]    The lattice points P of the wiring conductors  75  thus subjected to the cross wiring are lined up regularly in the form of a matrix. A through-hole passing through the printed circuit board is formed at each lattice point P. As the through-hole itself is not conductive, the wiring conductors  75  on both sides are not directly and electrically connected together. There are various methods of electrically connecting the wiring conductors  75  and one of them is to form conducting paths for signals by selectively forming a pass-through conductor in each through-hole as the lattice point P. The pass-through conductor may be a hollow pass-through conductor plated with conductive metal or a solid pass-through conductor such a rivet pin or a wire.  
         [0075]    The wiring conductors  75  on both sides of the printed circuit board are mutually connected together via the pass-through conductors, whereby an exchange of signals can freely be carried out between electric devices or electronic parts. In other words, it is possible to form a flexible internal circuit because connection ports on input and output signal sides can freely be selected and because an exchange of input and output signals can also be carried out without being restricted by conducting paths.  
         [0076]    The terminal portions  76  connected to the terminal fittings  55  housed in the L-shaped board connector  10  are formed in the edge portions  66   a  and  66   b  (see FIG. 3) of the printed circuit board  60 . The terminal portions  76  are equivalent to terminal portions of the respective wiring conductors  75  constituting the conductor circuits and drawn out to the adjoining edge portions  66   a  and  66   b  of the printed circuit board  60 . The number of poles of the input and output signals is increased by drawing out the terminal portions  76  from the edge portions  66   a  and  66   b  on the two sides, so that many of electric devices can be controlled simultaneously and electronically. In this case, these positions on the input and output sides are not restricted in particular and can selectively be assigned in either edge portion  66   a  or  66   b  on the two sides.  
         [0077]    The terminal portions  76  are formed on both sides of the printed circuit board so that they are made to solidly alternate with each other. The pitch of  20  the terminal portions  76  thus alternately arranged is set at ½time the pitch of the wiring conductors  75 . In other words, it is made possible to provide multiconductor (multi-pole) terminal portions  76  by arranging the terminal portions  76  drawn out to the edge portions  66   a  and  66   b  of the printed circuit board  60  alternately in the vertical two of upper and lower rows.  
         [0078]    The terminal portions  76  are unidirectionally drawn out at a tilted angle α (see FIG. 3) of 45° with respect to the ridgelines  67   a  and  67   b  of the edge portions  66   a  and  66   b . The reason for drawing out the terminal portions  76  unidirectionally is that the adjoining edge portions  66   a  and  66   b  of the printed circuit board  60  are simultaneously incorporated into the L-shaped board connector  10 .  
         [0079]    Although it is possible to incorporate the edge portions  66   a  and  66   b  of the printed circuit board  60  separately by dividing out the L-shaped board connector  10 , the terminal portions  76  need not be tilted in the 45° direction but the terminal portions  76  may be drawn out in a direction perpendicular to the ridgelines  67   a  and  67   b  of the edge portions  66   a  and  66   b . In the case of using the L-shaped board connector  10 , the advantage is that assembly workability is made improvable by simultaneously mating both the edge portions  66   a  and  66   b  of the printed circuit board  60  together.  
         [0080]    The reason for setting the tilted angle α of the terminal portions  76  is that the printed circuit board  60  according to this embodiment of the invention is square in shape and that the diagonal line CL 2  connecting the opposed corner portions  68   a  and  68   d  is in the 45° direction.  
         [0081]    Not only the board connector  10  according to this embodiment of the invention but also what has been applied for patent separately is applicable to the printed circuit board  60  thus having the conductor circuit on both sides of the board.