Abstract:
A flexible first circuit member ( 10 ) includes conductors ( 11 ) wired thereto. The conductors ( 11 ) include a first conductor group ( 12 ). The first circuit member defines an opening ( 14 ) having a first edge part ( 14   d ). The first conductor group ( 12 ) terminates at the first edge part ( 14   d ). A flexible second circuit member ( 13 ) is electrically connected to first conductor group ( 12 ) at the first edge part ( 14   d ).

Description:
BACKGROUND OF THE INVENTION  
         [0001]    The present invention relates to a connect structure of a flexible circuit board where a plurality of conductors wired to a flexible print circuit board are divided, being connected to a flexible circuit member.  
           [0002]    For example, a door of an automobile is provided with various electric equipment such as a power window driving mechanism, a door mirror driving mechanism, a door lock mechanism, a speaker or the like. In order to perform electrical connection for the electric equipment, many harnesses are wired. In this case, as a method for simplifying the wiring of the harnesses, collective wiring is conducted using a flexible print circuit board (FPC) on which a plurality of conductors have been printed. The plurality of conductors on the flexible print circuit board are respectively divided at a portion of the board reaching each electric equipment. Each of the divided conductor groups is connected to a flexible circuit member for branching, and each flexible circuit member connected/branched is connected to target electric equipment. In this case, as the flexible circuit member to be connected to the flexible print circuit board, a flexible and flat lead wire is used.  
         SUMMARY OF THE INVENTION  
         [0003]    An object of the invention is to provide a connect structure of a flexible circuit member where a plurality of flexible circuit members are easily drawn out from a flexible circuit board and where small-sizing of the flexible circuit board and overlapping arrangement of a plurality of flexible circuit members are allowed so that the simplification of fixing work of the flexible circuit members is achieved.  
           [0004]    In view of a first aspect, the invention is directed to a flexible circuit board. The board includes a flexible base member having an enclosed opening with a first edge part. The circuit board includes a circuit wired to the base member. The circuit includes the first circuit part terminating at the first edge part for electrical connection.  
           [0005]    Preferably, the base member has a second edge part away from the opening. The circuit includes a second circuit part terminating at the second edge part for electrical connection.  
           [0006]    Preferably, the second circuit part extends alongside the first circuit part.  
           [0007]    Preferably, the opening is configured in a rectangular shape.  
           [0008]    Preferably, the opening has a recess from the first edge part, extending alongside the first circuit part.  
           [0009]    In view of a second aspect of the invention, the invention is directed to a connect structure. The connect structure includes a flexible first circuit member including conductors wired thereto. The conductors include a first conductor group. The first circuit member defines an opening having a first edge part. The first conductor group terminates at the first edge part. The connect structure includes a flexible second circuit member electrically connected to first conductor group at the first edge part.  
           [0010]    Preferably, the first circuit member has a second edge part. The conductors include a second conductor group terminating at the second edge. The connect structure includes a flexible third circuit member electrically connected to the second conductor group at the second edge part.  
           [0011]    Preferably, the second and third circuit members are overlapped each other in a direction.  
           [0012]    Preferably, the opening includes recesses from both ends of the first edge part, extending alongside the first conductor group. 
       
    
    
     BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS  
       [0013]    These and other features, aspects, and advantage of the present invention will become better under stood with reference to the following description, appended claims, and accompanying drawings where:  
         [0014]    [0014]FIG. 1 is a perspective view showing a state before a flexible print circuit board and a flexible circuit member are accommodated in an electronic control unit, to which an interconnect structure of a flexible circuit member of a first embodiment of the present invention is applied;  
         [0015]    [0015]FIG. 2 is a perspective view of a connection fixture for the connection of a circuit member to the board according to the first embodiment of the present invention;  
         [0016]    [0016]FIG. 3 is a sectional view of a state where the circuit member is connected to the board according to the first embodiment of the present invention;  
         [0017]    [0017]FIG. 4 is a perspective view showing a state before the board and the circuit member are connected to each other according to the first embodiment of the present invention;  
         [0018]    [0018]FIG. 5 is a perspective view of a state showing a midway where the flexible circuit member connected to the board is wired from a back surface of the board to a surface thereof according to the first embodiment;  
         [0019]    [0019]FIG. 6 is a perspective view showing a modified embodiment of the board according to the first embodiment of the present invention; and  
         [0020]    [0020]FIG. 7 is a perspective view showing a state before a board and a circuit member are connected to each other according to a second embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0021]    Embodiment of the present invention will be explained below with reference to the drawings.  
         [0022]    As shown in FIG. 1, in a interconnect structure of a flexible circuit member according to this embodiment, as one example, a flexible print circuit board (FPC)  10 A for a control board is connected with flat and flexible first and second lead wires  20  and  30  each serving as a flexible circuit member. This flexible print circuit board  10 A is formed by bringing a conductive foil such as a copper foil in close contact with a surface of a base film, as known in general. The surface of the base film is covered with a cover film in an insulating manner. Using the conductive foil, a wiring pattern is printed in a desired shape by an etching process, a plating process or the like. On the other hand, the first and second lead wires  20  and  30  are respectively formed as flexible flat cables, where a conductive foil such as a copper foil is sandwiched in a base film using adhesive.  
         [0023]    As shown in FIG. 4, the board  10 A is wholly formed in a rectangular shape having a width W 0 . The first and second lead wires  20  and  30  are respectively formed in strip shapes having widths W 1  and W 2  (W 1 &gt;W 2 ).  
         [0024]    Also, a plurality of copper foils  11   a  to  11   h  serving as conductors are wired to the entire board  10 A. Four copper foils  11   a  to  11   d  of these copper foils are arranged on a central portion. Two copper foils  11   e  and  11   f  and two copper foils  11   g  and  11   h  are respectively arranged on both side edge portions. Then, the copper foils  11   a  to  11   d  on the central portion are defined as a first conductor group (one of conductor groups), and the first lead wire (one of flexible circuit members)  12  is connected to the first conductor group  12 . The copper foils  11   e  to  11   h  on both the side edge portions are defined as a second conductor group (the other of conductor groups)  13 , and the second lead wire (the other of flexible circuit bodies)  30  is connected to the second conductor group  13 .  
         [0025]    As shown in FIG. 4, four copper foils  21   a  to  21   d  are arranged in first lead wire  20  so as to correspond to the copper foils  11   a  to  11   d  of the first conductor group  12 . Four copper foils  31   a  to  31   d  are arranged in the second lead wire  30  so as to correspond to the copper foils  11   e  to  11   h  of the second conductor group  13 .  
         [0026]    Furthermore, as shown in FIG. 4, U-shaped cut-out in plan view is formed at a portion of the board  10 A which is close to one end thereof. A terminal end  12   a  of the first conductor group  12  is defined at a formation part  14   d,  as a first edge part, of the U-shaped cut-out  14  in plan view. The first lead wire  20 , as a second circuit member, is connected to the terminal end  12   a.  Also, a tongue (end)  15 , as a second edge part, is formed integrally at a central portion of one end of the flexible print circuit board  10 A. The second conductor group  13  is collected to this tongue  15  to define a terminal end  13   a.  The second lead wire  30 , as a third circuit member, is connected to the terminal end  13   a.    
         [0027]    As shown in FIG. 1, when the copper foils  11   a  to  11   d  on the board  10 A and the copper foils  21   a  to  21   d  of the first lead wire  20  corresponding thereto are mutually connected to each other, connection fixtures, each of which is so-called “piercing terminal”  40  shown in FIG. 2, are used. This piercing terminal  40  comprises a rectangular primary part  41  formed of such a conductor as a copper plate and a plurality of piercing claws  42  provided on both sides of the primary part perpendicularly thereto. Then, insulating films of connection ends on the copper foils  11   a  to  11   d  and the copper foils  21   a  to  21   d  are cut and removed (shown with oblique lines in Figure), and the copper foils of the connection ends are exposed in advance. Then, the piercing terminals  4  are arranged to extend over ends of one copper foils  11   a  to  11   d  and the other copper foils  21   a  to  21   d  to be connected. The piercing claws  42  are pierced into both side portions of the copper foils and the respective piercing claws  42  are caulked in opposing directions to each other. At this time, a case that the terminals  40  are fitted to the connection ends from back surfaces (back surface in Figure) thereof has been illustrated, but the present invention is not limited to this case. The terminals  40  may be fitted from a surface (surface in Figure) of the connection ends.  
         [0028]    Also, the copper foils  11   e  to  11   h  on the flexible print board  10 A and the copper foils  31   a  to  31   d  of the second wire  30  are mutually connected to each other. In this case, after insulating films of one copper foils  11   e  to  11   h  and the other copper foils  31   a  to  31   d  are cut and removed (shown with oblique lines in Figure) like the first lead wire, the terminals  40  are attached to extend over respective connection ends.  
         [0029]    As shown in FIG. 4, the cut-out  14  is wholly formed in a U-shape in plan view. The cut-out  14  has a primary opening  14   a  formed so as to extend in a width (W 0 ) of the flexible print board  10 A. This cut-out  14  has recess openings  14   b  and  14   c  which are formed so as to be continuous from both ends of the primary opening  14   a  and which extend towards a side where the first conductor group  12  has been arranged perpendicularly to the primary opening. As shown in FIG. 4, the primary opening  14   a  is formed so as to have a relatively large gap or width (S 1 ). Also, the recess opening  14   b  is formed so as to have a gap or width (S 2 ) smaller than that of the primary opening  14   a.    
         [0030]    Then, in order to the first and second lead wires  20  and  30  to the flexible print board  10 A, first, as shown in FIG. 4, in a state where the first lead wire  20  is disposed below the flexible print board  10 A, the connection end of the first lead wire  20  is connected to the terminal end  12   a  of the first conductor group  12 , using the terminals  40 . Next, in a state where the connection end of the second conductor group  13  is caused to match with the tongue  15 , the second lead wire  30  is connected to the terminal end  13   a  of the second conductor group  13 , using the terminals  40 . Thereby, as shown in FIG. 1, the first lead wire  20  and the second lead wire  30  are connected to the flexible print circuit board  10 A such the former is positioned on an upper side and the later is positioned on a lower side. These first and second lead wires  20  and  30  are overlapped up and down in the same direction to be drawn out.  
         [0031]    Thus, as shown in FIG. 1, the board  10 A connected with the first and second lead wires  20  and  30  together with the connection ends of the first and second lead wires  20  and  30  is accommodated in an electronic control unit  50 . This control unit  50  is provided with an upper casing  50   a  made of synthetic resin and a lower casing  50   b  made of synthetic resin. This unit  50  is wholly formed to conform to the board  10 A, and it is formed at its one end with a drawing-out opening  51  for drawing out the first and second lead wires  20  and  30 .  
         [0032]    As shown in FIG. 3, the upper casing  50   a  is put on the outer periphery of the lower casing  50   b.  An accommodating part  52  for accommodating the flexible print board  10 A is formed between both the casings. When the upper casing  50   a  and the lower casing  50   b  are mated with each other, protrusions  53  protruded from the lower casing  50   b  are fitted into a fitting holes  53   a  of the upper casing  50   a  to be positioned. Furthermore, lock claws (engagement part)  54 , protruded from side faces of the lower casing  50   b,  are engaged with lock holes (engagement part)  54   a  of the upper casing  50   a  so that the lower casing is prevented from falling off. At this time, the protrusions  53  are positioned at corners C 1  and C 2  on both sides of the end of the flexible print circuit board  10 A. The protrusion  53  are inserted into insertion holes  16  formed in the corners C 1  and C 2  so that the board  10 A is prevented from falling off against pulling force acting on the first and second lead wires  20  and  30 .  
         [0033]    Also, a receiving groove  55  for receiving the terminals  40  which have connected the first and second lead wires  20  and  30  to the board  10 A is formed in the lower casing  50   b.  A front groove  55   b  and a rear groove  55   c  are formed in the this receiving groove  55  so as to sandwich a shallow shelf which has the same depth as the thickness of one of the first and second lead wires  20  and  30  and which is positioned at a central portion of the receiving groove  55 . As shown in FIG. 1, in a case that the first lead wire  20  is arranged below the second lead wire  30 , the piercing terminals  40  connecting this first lead  20  is received in the rear groove  55   c.  As described below, the front groove  55   b  receives the piercing terminals  40  connecting the second lead wire  30  when the second lead wire  30  is wired below the first lead wire  20 .  
         [0034]    As explained above, in the connection structure of a flexible circuit member according to the present embodiment, such a structure is employed that the first lead wire  20  is connected to the board  10 A and the second lead wire  30  is connected to the board  10 A. That is, the cut-out  14  formed in an intermediate portion to the board  10 A serves as the terminal end  12   a  of the first conductor group  12 , so that this terminal end  12   a  is connected with the first lead wire  20 . Accordingly, the first lead wire  20  connected to the first conductor group  12  is drawn out as if it is branched from the intermediate portion of the board  10 A in a direction of the thickness thereof. Furthermore, the second lead wire  30  connected to the second conductor group  13  is drawn out as if it is branched from one end of the board  10 A in a direction of extension of the board. Accordingly, it becomes possible to draw out the first lead wire  20  and the second lead wire  30  in such a manner as overlapping up and down in the same direction. These lead wires  20  and  30  can be prevented from being positioned side by side in a conventional manner.  
         [0035]    Accordingly, even in a case that the width (W 1 +W 2 ) of the first lead wire  20  plus the second lead wire  30  is larger than the width W 0  of the board  10 A, the total width of the first and second lead wires  20  and  30  to be drawn out from the flexible print board  10 A is not the summed width of the respective widths W 1  and W 2  of the first and second lead wires  20  and  30 , but it becomes a wider one of the first and second lead wires. Namely the width W 1  of the first lead wire  20  becomes the width for drawing-out in this embodiment. For this reason, a down-sizing is achieved by reducing the width W 0  of the board  10 A. Restriction on the widths of the first and second lead wires  20  and  30  is relaxed largely, and the degree of freedom for wiring or circuit design is expanded.  
         [0036]    Also, the first and second lead wires  20  and  30  are drawn out in a manner overlapping up and down in the same direction, so that the lead wires  20  and  30  protruding from the control unit  50 , respectively, can be collectively fixed by fixing means  60  such as a tape, a clip or the like, thereby facilitating a fixing work at that time.  
         [0037]    Furthermore, since the cut-out  14  is wholly formed in a U shape in plan view by the primary opening  14   a  and the recess openings  14   b,  the terminal end  12   a  of the first conductor group  12  can be bent freely in the direction of the thickness of the board  10 A through the recess openings  14   b.  Therefore, when the first lead wire  20  is connected to the first conductor group  12 , the terminal end  12   a  can be pulled out from the board  10 A in the connection direction, in the back surface direction in this embodiment, to be connected, so that the connecting work is easily and accurately performed.  
         [0038]    In addition, the case that the first and second lead wires  20  and  30  connected to the board  10 A are wired such that the first lead wire  20  is positioned below the second lead wire  30  has been illustrated. In the wired state, the lead wire  20  may be arranged on an upper side of the second lead wire  30  according to mounting position of electric equipment to be respectively connected. In this case, as shown in FIG. 5, while the first lead wire  20  is further being bent in a curved state, the tip end thereof is caused to pass through the generally U-shaped cut-out  14 . Accordingly, when the first lead wire  20  is caused to pass through the board  10 A from the back surface to the surface thereof (or from the surface to the back surface), the opening area of the cut-out  14  is enlarged through the recess openings  14   b,  so that wiring changing work is performed smoothly.  
         [0039]    Incidentally, in the first embodiment, the case that one lead wire is connected to the cut-out side of the board has been shown. The present invention is not limited to this embodiment, but such a structure can be employed that a plurality of lead wires are connected to the cut-out side of the board. Also, as a modified embodiment of the first embodiment shown in FIG. 6, such a structure can be employed that a central connection part (the terminal end  13 a of the second conductor group  13 ) of one end of a flexible print board  10 B does not project.  
         [0040]    [0040]FIG. 7 is a perspective view showing a state before a flexible print board  10 C and the flexible circuit member  20  are connected to each other according to a second embodiment of the present invention.  
         [0041]    This second embodiment is different from the first embodiment in that the terminal end (connection part)  13   a  of the second conductor group  13  is not provided at the central portion of one end of the board  10 C and the second conductor group  13  extends continuously from a central portion of one end of the board  10 C so that a flexible circuit member part  17  with a narrow width (W 2 ) is formed integrally in a projecting manner.  
         [0042]    Then, a cut-out  14  is formed at a predetermined portion of the board  10 C. This embodiment is similar to the first embodiment regarding a point that a terminal end  12   a  of a first conductor group  12  is defined at the formation part  14   d  of the cut-out  14  and a flat and flexible first lead wire (flexible circuit member)  20  is connectable to this terminal end  12   a.  The first lead wire  20  is drawn out from the board  10 C with a small width in such a manner that the flexible circuit member part  17  and the first lead wire  20  overlap each other. Thereby, the down-sizing of the board  10 C can be achieved unlike the conventional art where a plurality of circuit members are arranged side by side at one end of the board  10 C. The limitations on the first lead wire  20  and the circuit member part  17  is relaxed largely to expand the degree of freedom for wiring or circuit design.  
         [0043]    As explained above, since it is unnecessary to arrange a plurality of flexible circuit members at an end of a flexible print board side by side in the conventional manner, a down-sizing of the board is achieved. The limitations on the widths of the circuit member and the circuit member part of the end side of the board are largely relaxed and the degree of freedom for wiring or circuit design is expanded.  
         [0044]    A plurality of circuit members are drawn out from a board with a small width such that they overlap one anther. Thereby, it is unnecessary to arrange a plurality of circuit members at an end of a board side by side so that the down-sizing of the board can be achieved. By relaxing limitations on widths of respective circuit members, the degree of freedom for wiring or circuit design is expanded.  
         [0045]    It becomes possible to fix a plurality of flexible circuit members collectively so that fixing work for them is easily and securely performed.  
         [0046]    A terminal end of one of the conductor groups provided within the U-shaped cut-out is bent freely in a direction of the thickness of a board through an recess openings. Thereby, connection of one of the conductive groups and one of the circuit members is easily and accurately performed. Also, one of circuit members connected to one of conductor groups of a board is replaced to a surface side or a back surface side of the board up and down through the cut-out, so that wiring workability of circuit members is further improved.  
         [0047]    The entire contents of Japanese Patent Applications P2000-333448 (filed Oct. 31, 2000) are incorporated herein by reference.  
         [0048]    Although the invention has been described above by reference to certain embodiments of the invention, the invention is not limited to the embodiments described above. Modifications and variations of the embodiments described above will occur to those skilled in the art, in light of the above teachings. The scope of the invention is defined with reference to the following claims.