Abstract:
A wire connector for connecting wires to each other having a small wire collection space and which transmits a small shock load to the wires connected therein is formed by bending a metal plate at both sides of a central portion to form a closed ring having open ends at both ends thereof. Depressions that protrude toward the interior of the closed ring so that they approach each other are formed at the central portions of both side walls of the closed ring. A vertically extending slot is formed in each of the side walls. Wires are inserted through each of the open ends and the slots, then pressure is applied so that the portion where the ends of the bent metal plate are coupled and the central portion approach each other. The pressure compressively deforms the connector, and the wires are electrical connected to each other.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention relates to a wire connector for connecting wires to each other.  
         RELATED APPLICATION  
         [0002]    Priority is claimed based on Japanese Patent Application No. 2002-3150 filed on Jan. 10, 2002 and Japanese Patent No. 2002-280742 filed on Sep. 26, 2002, which are hereby incorporated by reference.  
         DESCRIPTION OF THE RELATED ART  
         [0003]    There are various existing methods for connecting wires to each other. Among known methods are the use of press contact terminals that tear the outer covering of a wire to electrically connect the wire core to a terminal, and the use of crimp terminals that fix the core to a terminal by plastic deformation of the terminal when establishing an electrical connection therebetween. For example, a connection structure for connecting wires to each other by use of a press contact terminal is disclosed in Japanese Unexamined Patent Publication No. 11(1999)-26038. The press contact terminal disclosed therein comprises a base portion bent into a square enclosure, and press contact plate portions provided integrally with the base portion, protruding from the upper and lower surfaces of the four sides thereof. Press contact blades are formed by cutting away the press contact plate portions from the distal ends thereof. When a plurality of wires is pressed into these press contact blades, the outer coverings are torn, and the cores of the wires contact the press contact plate portion. That is, a plurality of wires is connected by press contacting the press contact terminal, and electrical connections are established among the wires via the press contact terminal.  
           [0004]    In the case of the crimp connection, wires are inserted through, for example, both open ends of an annular electrical terminal. Then, the terminal is crushed, that is, crimped, by an external force to hold the wires fixed to each other and to establish electrical connections therebetween. This connection method is well known as a parallel splice method.  
           [0005]    In recent years, thin liquid crystal displays have been used for compact electronic equipment such as lap top computers. These displays contain elongated fluorescent tubes (backlights) for illuminating the liquid crystal display panel from behind. Dumet wires protrude from the ends of the fluorescent tubes, and wires that extend from the main body of the electronic equipment are connected to these Dumet wires via terminals. Compact terminals are required, as the space around the liquid crystal display panel is extremely narrow. The conventional press contact terminals are difficult to arrange therein, as their size is large. In the case that the press contact terminals are miniaturized, the press contact plates become narrow. Therefore, problems arise in that sufficient strength cannot be obtained to tear the outer coverings of the wires and effect press contact, and thus it becomes difficult to hold the press contact connected wires stably for a long period of time.  
           [0006]    With regard to the crimp terminal, although sufficient strength can be obtained, the crimping requires a large load. As a result, shock is generated during the crimping of the terminal. The shock is transmitted through the wires (Dumet wires) to the fluorescent tubes, resulting in cases in which the fluorescent tubes are damaged.  
         SUMMARY OF THE INVENTION  
         [0007]    The present invention has been developed in view of the points described above. It is a primary objective of the present invention to provide a wire connector that has a small wire collection space, capable of obtaining sufficient strength even when miniaturized, and imparts a small shock load to the wires connected during the connection process. Further, it is another objective of the present invention to provide a wire connector that provides highly reliable electrical connections.  
           [0008]    The wire connector of the present invention comprises:  
           [0009]    a closed ring formed by bending a metal plate to bring both ends thereof together to form a cylinder;  
           [0010]    open ends for wires to pass through provided at both ends of the closed ring;  
           [0011]    depressions which are recessed towards the interior of the closed ring along an axis thereof that passes through the open ends, at both sides of the coupling portion of the metal plates, so that the depressions face each other; wherein  
           [0012]    electrical connections are established among a plurality of wires that are inserted through the open ends of the closed ring, brought into contact with each other due to deformation of the depressions from pressure applied to the closed ring in a direction that causes the coupling portion of the metal plates and a wall of the closed ring opposite thereto to approach each other.  
           [0013]    In addition, a construction may be adopted wherein:  
           [0014]    slots that extend between the coupling portion of the metal plates and the wall opposite thereto are formed in the closed ring, wherein electrical connections are established between a first set of wires that are inserted through at least one of the two open ends and a second set of wires inserted through the slots so as to intersect with the first set of wires, wherein connection is made due to deformation of the depressions from pressure applied to the closed ring in a direction that causes the coupling portion of the metal plates and a wall of the closed ring opposite thereto to approach each other.  
           [0015]    Further, a construction may be adopted wherein:  
           [0016]    the slots are formed so as to face each other, at opposing positions of the closed ring; and  
           [0017]    the slots comprise wide portions through which the second set of wires are inserted, narrow portions at which the second set of wires are positioned when the depressions are deformed, and intermediate portions that gradually vary in width between the wide portions and the narrow portions, along which the second set of wires pass during deformation of the depressions.  
           [0018]    In addition, it is preferable that:  
           [0019]    the coupling portion of the metal plates is formed by overlapping the two ends of the metal plate; and  
           [0020]    the overlapped portion and the wall opposite thereto are formed as flat surfaces parallel to each other.  
           [0021]    According to a first embodiment of the present invention, a construction may be adopted wherein:  
           [0022]    at least one pair of beads is formed on the surface of the wall of the closed ring opposite the coupling portion of the metal plates, the beads extending towards the coupling portion of the metal plates, while being separated from each other.  
           [0023]    According to a second embodiment of the present invention, a construction may be adopted wherein:  
           [0024]    the wall of the closed ring opposite the coupling portion of the metal plates is extended, to have an extended portion that protrudes from the opening of the closed ring. It is preferable that the extended portion is of a width corresponding to the wall opposite the coupling portion of the metal plates, and further have arcuate portions along each side wall of the closed ring.  
           [0025]    Here, the referents of the term “wires” include flexible single wires, twisted wires comprising a plurality of flexible wires twisted together, and a single or a plurality of comparatively stiff wires such as Dumet wires.  
           [0026]    The wire connector of the present invention comprises a closed ring formed by bending a metal plate to bring both ends thereof together to form an enclosure; and depressions that are recessed towards the interior of the closed ring along an axis thereof that passes through the open ends at both sides of the coupling portion of the metal plates so that the depressions face each other; wherein electrical connections are established among a plurality of wires that are inserted through the open ends of the closed ring by being brought into contact with each other due to deformation of the depressions from pressure applied to the closed ring in a direction that causes the coupling portion of the metal plates and a wall of the closed ring opposite thereto to approach each other. Therefore, it exhibits the following effects.  
           [0027]    That is, because the wires are fixed to each other by crimping the closed ring, a compact wire connector having a small wire collection space and sufficient connection strength is obtained. In addition, by the depressions being formed in the closed ring, the wires can be crimped together with a comparatively small force employing pliers or a manual press. Therefore, the shock load imparted on the wires to be connected during the connection of the wires is small, and the risk of damaging a member to which the shock is transmitted via the wires is small. Further, wires of a broader range of diameters can be connected to each other than with a conventional press contact connection.  
           [0028]    In addition, in the case that a construction is adopted wherein slots that extend between the coupling portion of the metal plates and the wall opposite thereto are formed in the closed ring, and electrical connections are established between a first set of wires which are inserted through at least one of the two open ends and a second set of wires inserted through the slots, which are brought into contact with each other due to deformation of the depressions from pressure applied to the closed ring in a direction that causes the coupling portion of the metal plates and a wall of the closed ring opposite thereto to approach each other, cruciform connections can be established as well as parallel splicing, in addition to the effects listed above. An additional effect of enabling a larger contact surface than a conventional press contact connection is also obtained.  
           [0029]    Further, in the case that a construction is adopted wherein the slots comprise wide portions (through which the second set of wires are inserted), narrow portions, and intermediate portions that gradually vary in width between the wide portions and the narrow portions, positive connections are enabled by the wires that are inserted through the slots being guided to the narrow portions.  
           [0030]    In the case that a construction is adopted wherein the coupling portion of the metal plates is formed by overlapping the two ends of the metal plate, and the overlapped portion and the wall opposite thereto are formed as flat surfaces parallel to each other, positive connections among wires are enabled by accurate crushing of the depressions even with simple hand tools.  
           [0031]    In addition, the mechanical strength of the connector after compression is high, and not likely to deform. In the case that at least one pair of beads is formed on the surface of the wall of the closed ring opposite the coupling portion of the metal plates, the beads extending towards the coupling portion of the metal plates while being separated from each other, when a plurality of wires is to be connected, the cores thereof are controlled by the pair of beads so as to not spread outwardly. That is, the beads gather the cores towards the center of the wire connector, thereby improving the close contact property of the cores during connection of the wires, and consequently the reliability of the electrical connection. Further, the beads are capable of directly pressing on a portion of the cores during the connection of the wires, improving the reliability of the electrical connection.  
           [0032]    In the case that the wall of the closed ring, opposite the coupling portion of the metal plates, is extended to have an extended portion that protrudes from the opening of the closed ring, the cores of the wires can be temporarily placed on the extended portion, then inserted into the open end. Therefore, the workability of the insertion of the cores to the closed ring is improved during the operation of connecting the wires. Also at this time, the outer coverings of the covered wires may be placed to abut the edge of the extended portion to perform positioning of the covered wires, further improving the workability. Further, if during the connection of the wires, covered portions of the wires are erroneously inserted within the open ends, this defect can be easily discriminated by visual inspection of the extended portion. In other words, a correct connection state can be confirmed easily by visual inspection of the wires on the extended portion. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0033]    [0033]FIG. 1 is a plan view that shows the connector along with a portion of a carrier strip.  
         [0034]    [0034]FIG. 2 is a front view of the connector of FIG. 1.  
         [0035]    [0035]FIG. 3 is a side view that shows the connector of FIG. 1 along with a portion of the carrier strip.  
         [0036]    [0036]FIG. 4 is a view of the connector of FIG. 1 in an expanded state.  
         [0037]    [0037]FIG. 5 is a plan view that shows the state of the connector of the present invention when a cruciform connection is made between two wires.  
         [0038]    [0038]FIG. 6A shows a front view of the connector of FIG. 5 along with the wires in the state in which a cruciform connection is made.  
         [0039]    [0039]FIG. 6B shows a cross sectional view taken along a line  6 B- 6 B in FIG. 6A.  
         [0040]    [0040]FIG. 7A is a plan view of a connector according to another embodiment of the present invention.  
         [0041]    [0041]FIG. 7B is a side view of the connector of FIG. 7A.  
         [0042]    [0042]FIG. 8A is a front view of the connector of FIG. 7A.  
         [0043]    [0043]FIG. 8B is a bottom view of the connector of FIG. 7A.  
         [0044]    [0044]FIG. 9A is a front view similar to FIG. 6A that shows the state of the connector of FIG. 7A when wires are connected thereby.  
         [0045]    [0045]FIG. 9B is a cross sectional view taken from the same direction as that of FIG. 9A. 
     
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0046]    Hereinafter, the preferred embodiments of the wire connector of the present invention (hereinafter simply referred to as “connector”) will be described in detail with reference to the attached drawings. FIG. 1 is a plan view that shows the connector  1  along with a portion of a carrier strip  2 . FIG. 2 is a front view of the connector  1 . FIG. 3 is a side view that shows the connector  1  along with a portion of the carrier strip  2 . FIG. 4 is a view of the connector  1  in an expanded state. Hereinafter, a description will be given with reference to FIG. 1 through FIG. 4.  
         [0047]    First, a description will be given with reference to FIG. 4. The connector  1  is constructed by a substantially rectangular plate member  4 , punched out of a metal plate capable of plastic deformation, such as a phosphor bronze plate. The dimensions of the plate member  4  are extremely small, for example, approximately 7 mm×1.8 mm. A rectangular protrusion piece  8  is provided integrally with the plate member  4 , at an edge  6  thereof on one end of a central line X which extends in the longitudinal direction of the plate member  4 . A cutout  12  wider than the protrusion piece  8  is formed at the edge  10  on the other end of the central line X. In addition, a pair of slots  14  that extends along the central line X is formed by being punched out of the plate member  4 . These slots are symmetrically formed on either side of another central line Y which is perpendicular to the central line X.  
         [0048]    The inner portions of the slots  14 , that is, the portions closer to the central line Y, are formed as narrow portions  14   a , and the outer portions of the slots, that is, the portions closer to the edges  6  and  10 , are formed as wide portions  14   b . The intermediate portions that link the narrow portions  14   a  and the wide portions  14   b  are formed as tilted intermediate portions  14   c . The dimensions of the slots are set so that the widths of the wide portions  14   b  and the narrow portions  14   a  in the direction of the central line Y are, for example, 0.6 mm and 0.3 mm, respectively. Wires W 4 , which are Dumet wires (see FIG. 5), are inserted into the slots  14 . The connection state of the wires W 4  will be described later.  
         [0049]    Continuing with reference to FIG. 4, a closed ring is formed by bending the plate member  4 , which has been punched out in this manner, around its central portion  20  so that the edge  10  overlaps with the edge  6 . At this time, the protrusion piece  8  enters the wide portion  14   b  in the vicinity of the cutout  12 . The protrusion piece  8  that enters the wide portion  14   b  is slightly curved upward, and engages with the slot  14  so that it is not dislodged therefrom, as most clearly shown in FIG. 2.  
         [0050]    Open ends  5  and  7  (see FIG. 1, FIG. 2, and FIG. 3) are formed at both sides of the closed ring. The end  16  of the plate member  4  at which the protrusion piece  8  is formed, and the end  18  at which the cutout  12  is formed, are overlapped, and form a planar coupling portion  17  (upper wall) (see FIG. 2 and FIG. 3). As most clearly shown in FIG. 2, the central portion  20 , which becomes the wall opposite the coupling portion  17 , is formed as a planar surface parallel to the coupling portion  17 .  
         [0051]    As most clearly shown in FIG. 3, the slots  14  are formed in each of the side walls  21  of the closed ring to extend between the central portion  20  and the coupling portion  17 .  
         [0052]    Depressions  21   a  are formed in each of the side walls  21  so that their central portions  22  approach each other. By the formation of these depressions  21   a , the connector  1  assumes a shape similar to that of a “Σ” and a “3” facing each other and integrally formed, when viewed from the front. The connector  1  formed in this manner is indicated in FIG. 1 through FIG. 3. Note that it is conceivable to form the depressions  21   a  to protrude towards the exterior. However, in this case, the projected area of the connector will increase after compression thereof. For this reason, it is advantageous to form the depressions  21   a  so that they protrude toward the interior, from the viewpoint of miniaturzation of the connector  1  after compression thereof.  
         [0053]    The central portions  22 , in which the depressions  21   a  have been formed, are capable of being deformed with a comparatively low amount of force. Therefore, they can be easily deformed with hand tools such as pliers or a manual press (not shown). In addition, the shock force during deformation is small, therefore the shock force transmitted through the wires being connected is also small. Accordingly, the connector  1  may be utilized even in the case that the members to be connected, such as fluorescent tubes, are fragile. Note that a notch  26  (see FIG. 3) is formed in a link portion  23  (see FIG. 1 and FIG. 3) between the connector  1  and the carrier  2  along the broken line  24  of FIG. 1. The connector  1  is separated from the carrier  2  by being cut at the notch  26 .  
         [0054]    The connector  1  formed in the manner described above is extremely compact. Each of the dimensions of height, width, and depth may be less than or equal to 2 mm. The connection of wires to each other using the connector  1  can be performed by a plurality of bare wires being inserted through the open ends  5  and  7  in the direction of an axial line C of the closed ring, then the connector  1  being deformed. For example, wires W 1  and W 2 , which are to be connected, are inserted so that they pass through regions  28  and  30  above and below the central portions  22 , as indicated by the broken lines in FIG. 2. Then a force F is applied from above and below the connector  1 , that is, to the coupling portion  17  and to the central portion  20  (bottom surface), by a tool (not shown), such as pliers, to deform the depressions  21   a  of the central portions  22 . Because the coupling portion  17  and the central portion  20  are parallel planes, the connector  1  can be crimped easily and accurately, even with simple tools. By the crimping, the wires W 1  and W 2  are fixed together and brought into contact with each other, thereby establishing an electrical connection. Conventional crimp terminals have a narrow range of wire diameters to which they can be applied, due to restrictions in the shapes thereof after crimping. However, the connector  1  of the present invention is applicable to wires of a greater range of diameters than a conventional crimp terminal.  
         [0055]    The wires W 1  and W 2  shown in FIG. 2 may be inserted from opposite directions, into the open ends  5  and  7  respectively, or they may be inserted from the same side, in the same direction. In addition, the wires W 1  and W 2  may both be inserted into either the upper region  28  or the lower region  30 , depending on their sizes. That is, if the wires are of a comparatively small diameter, they can be bundled and inserted into either the upper region  28  or the lower region  30 . Furthermore, the wires W 1  and W 2  may be bare wires, or covered wires having their insulative coverings removed only at the portions which are crimped.  
         [0056]    Next, a case will be described in which a cruciform connection is made by a plurality of wires that intersect each other. In order to make this connection, a first wire is inserted through the lower region  30 , and a second wire is inserted through the slots  14  and a connection is established forming a cross. The cruciform connection will be described with reference to FIG. 5 and FIG. 6. FIG. 5 is a plan view that shows the state of the connector  1  when a cruciform connection is made between two wires. FIG. 6A shows a front view of the connector  1  along with the wires in the state in which a cruciform connection is made. FIG. 6B shows a cross sectional view taken along a line  6 B- 6 B in FIG. 6A.  
         [0057]    In the case of a cruciform connection, a first wire W 3 , comprising a plurality of thin wires  32  twisted together, is inserted through the lower region  30  from the open end  5 , as shown in FIG. 5. Then, a second wire W 4 , for example, the wire W 4  of a fluorescent tube  34 , is inserted through the wide portions  14   b  of the slots  14 . The wire W 4 , which is a Dumet wire, is a comparatively rigid single uncovered wire. It has substantially the same thermal expansion coefficient as hard glass and ceramics, and has characteristics that it has good concordance with glass, as well as good workability.  
         [0058]    Then in the same manner as in the previous case, pressure is applied from above and below the connector  1  by a tool such as pliers. As a result, the coupling portion  17 , at the overlapped ends  16  and  18 , and the central portion  20  push the wire W 3  and the wire W 4  toward each other. When the pressure is continuously applied, the depressions  21   a  in the central portions  22  are crushed by deformation, and the wire W 4  is press fit into the narrow portions  14   a  (see FIG. 3) by pressure from the upper wall  17 . At this time, the edges of the narrow portions  14   a  of the slots  14  dig into the wire W 4 . Then, pressure continues to be applied until the wire W 3  and the wire W 4  are solidly fixed to each other in a state of close contact. The pressure is ceased when an electrical connection is established between the wires W 3  and W 4 .  
         [0059]    The state at this time is shown in FIG. 6A. Note that FIG. 6 is a model drawing for illustrative purposes, and that dimensions of the parts therein are not necessarily proportional to those in FIG. 5. The connector  1  is plastically deformed to a state in which the wire W 4  is strongly pressed against the wire W 3 , and maintains this shape. The wire W 3  and the wire W 4 , in a state of direct contact with each other, are crimped between the upper wall  17  and the central portion  20 . In addition, the wire W 4  contacts the upper wall  17  over a wide area, as shown in FIG. 6A, while contacting the slots  14  as described previously. The contact region between the wire W 4  and the slots  14  are wide regions that extend from the depressions  21   a  to the outer ends of the central portions  22  (the overlapped side walls  21 ) as shown in FIG. 6A. Accordingly, the contact region can be made larger than that of a conventional press contact connection.  
         [0060]    As described above, the connector  1  comprises elements of both a crimp connector and a press contact connector. In addition, the wire W 3  contacts the connector  1  over a wide range, across the central portion  20  and the central portions  22 , as shown in FIG. 6B. Accordingly, the wires W 3  and W 4  are electrically connected via the connector  1  in addition to their direct contact with each other, further increasing the reliability of the connection. In addition, because bare wires directly contact each other, positive electrical connections are capable of being obtained, regardless of the degree of conductivity of the connector.  
         [0061]    Note that the wires W 1 , W 2 , W 3 , and W 4  may be either bare wires, or covered wires having their insulative coverings removed only at the portions thereof which are crimped or press contacted. In addition, the wires W 3  and W 4  may be either single wires, or a twisted wire comprising a plurality of thin wires twisted together.  
         [0062]    In the present embodiment, the coupling portion  17  was formed by overlapping the ends  16  and  18 . In this case, the rigidity of the coupling portion  17  formed by the overlapped ends  16  and  18  is high, therefore it provides an advantage that the connector  1  is not likely to deform after compression thereof. However, the coupling portion  17  may alternatively be formed by the ends  16  and  18  abutting each other.  
         [0063]    Next, a second embodiment of the present invention will be described. FIG. 7 and FIG. 8 show a connector  51  according to the second embodiment. FIG. 7A is a plan view of the connector  51 . FIG. 7B is a side view of the connector  51 . FIG. 8A is a front view of the connector  51 . FIG. 8B is a bottom view of the connector  51 . Hereinafter, a description will be given with reference to FIG. 7 and FIG. 8. Note that regarding the description, the same parts will be denoted by the same reference numerals.  
         [0064]    The connector  51  of the second embodiment differs from the connector  1  of the first embodiment in that a pair of beads  86  is provided on the bottom wall  70  (central portion) thereof. The beads  86  extend along the direction of an axial line C (see FIG. 7A and FIG. 8B) of the connector  51 , and are separated from each other in a direction perpendicular to the axial line C, at substantially equal distances from the axial line C. The details of the beads  86  will be described later. Further, another difference between the connector  51  and the connector  1  of the first embodiment is that an extended portion is provided on the bottom wall  70 . The other structures of the second embodiment are similar to those of the first embodiment. Therefore, redundant descriptions will be omitted, and the description will focus mainly on only the points which are different.  
         [0065]    As most clearly shown in FIG. 7A and FIG. 7B, the bottom wall  70  is provided with an extended portion  88  that extends outward on the side of an open end  55 . The extended portion  88  is provided on the opposite side from the notch  26  formed between the connector  51  and the carrier strip  2 . The extended portion  88  protrudes from the bottom wall  70  for approximately ¼ the distance between the open end  55  and an open end  57 . The width of the extended portion  88 , that is, the dimension thereof in the direction of arrow  92  of FIG. 7A is substantially equal to the width of the bottom wall  70 . However, the lateral edges of the extended portion  88  are formed as arcuate portions  90 , which rise slightly along side walls  71 . The arcuate portions  90  prevent sudden bends in a plurality of wire cores, that is, wire W 3  (see FIG. 9), which are inserted through the open end  55 , at the portion thereof which is crimped, in the width direction of the extended portion  88  indicated by the arrow  92  (FIG. 7A).  
         [0066]    The terminal edge  88   a  (see FIG. 7A and FIG. 7B) of the extended portion  88  is substantially parallel to the terminal edge of the open end  55 . In the case that wire W 3  is a covered wire, the outer covering  94  thereof is removed to expose the cores, that is, wire W 3 . When the wire W 3  is inserted into the open end  55 , the cut edge  94   a  (see FIG. 7A) of the outer covering  94  is made to abut the terminal edge  88   a  This abutment prevents erroneous entry of the outer covering  94  within the open end  55  of the connector  51 , which would cause a connection failure. Further, the provision of the extended portion  88  facilitates the insertion operation of the wire W 3 , as the wire W 3  can be placed on the extended portion  88  from above, then inserted into the open end  55 . In other words, because the need to aim the wire W 3  toward the open end  55  is obviated, the burden on an operator is reduced.  
         [0067]    A pair of serrations  93  (see FIG. 7B), extending in the vertical direction on both sides of slots  64  and protruding toward the interior of the connector  51 , is formed on the inner surfaces of the side walls  71  at the lower portions thereof. The serrations  93  dig into the wire W 3  inserted from the open end  55  and/or the open end  57  and prevent the wire W 3  from being pulled out.  
         [0068]    As most clearly shown in FIG. 8, a pair of beads  86  extending in the direction of the axial line C and separated from each other is formed on the bottom wall  70  so that the beads  86  protrude toward the interior of the connector  51 . In the present embodiment, a single pair of beads  86  is formed. However, a construction may alternatively be adopted wherein the beads are divided, and a plurality of pairs thereof is formed. During connection of the wires, the wire W 3  is inserted between the beads  86 ,  86  and crimp connected. The connection established in this manner will be described with reference to FIG. 9.  
         [0069]    [0069]FIG. 9 a  is a view similar to FIG. 6A that shows the state of the connector  51  when the wire W 3  and the wire W 4  are connected thereby. FIG. 9B is a cross sectional view taken from the same direction as that of FIG. 9A. The wire W 3  is inserted between an upper wall  67  and the bottom wall  70 , while at the same time being arranged between the two beads  86 ,  86 . Thereafter, the connector  51  is compressed so that the upper wall  67  and the bottom wall  70 , which is the wall opposite the upper wall  67 , approach each other. By this compression, the wire W 4  and the wire W 3  come into close contact with each other as shown in FIG. 9A and FIG. 9B, and an electrical connection is established therebetween. The wire W 3  is positioned between the beads  86 ,  86 , so that it is crimped in a state in which it is gathered at the central portion of the connector  51  without spreading laterally, as shown in FIG. 9A. In other words, the beads  86 ,  86  serve a centering function with respect to the wire W 3 .  
         [0070]    As a result, the close contact properties of the core wires that make up the wire W 3  with each other are improved, as well as the close contact property between the wire W 3  and the wire W 4 . Thereby, the reliability of the electrical connection therebetween is also improved. In addition, even in a case in which the wire W 3  spreads laterally, as shown in FIG. 9, the right side bead  86  digs into the wire W 3  while pressing the wire W 3  against the wire W 4 , to more positively connect the two with each other.  
         [0071]    In the connector  51  which has established a connection in the manner described above, the wire W 3  is positioned on the extended portion  88 , while the outer covering  94  is positioned outside of the extended portion  88 . Therefore, the state of the electrical connection alter the wires are in place can be easily recognized by visual inspection. That is, a risk of a faulty connection can be easily recognized in the case that the outer covering  94  of the wire W 3  has entered beyond the extended portion  88 .