Abstract:
An insulation-piercing connector includes a connector body made of an insulating material, and a plurality of contacts made of a resilient conductive metal. Each of the contacts consists of a contact element to be connected to a contact of a mating connector, a fixing element carried by the connector body and a U-shaped piercing terminal element extending from a surface of the connector body and embracing a wire between legs of the U-shaped element. The contacts are arranged staggered in at least two rows. A cover is maade of an insulating material and formed with terminal element receiving grooves for receiving the U-shaped elements of the contacts. When the cover is covered onto the connector body, the cover forces wire into the U-shaped elements and embraces the wires between the cover and the connector body. Surfaces of the connector body for embracing the wires in conjunction with the cover are raising inclination surfaces from a side of the U-shaped piercing elements in one row toward above the U-shaped piercing elements in the othe row to form alternately reversely inclined surfaces, and surfaces of the cover for embracing the wires are inclination surfaces auxiliary with said alternately inclined surfaces of the connector body.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to an insulation-piercing connector capable of connecting wires in high density. 
     Owing to the development of integrated circuit elements and other semiconductor parts, miniaturization of various kinds of electronic appliances has progressed. With such a progression, requirements have been also raised for miniaturization of connectors for use in connection between the electronic appliances. 
     Therefore, with insulation-piercing connectors, the following modifications have been effected. As shown in FIG. 1a, in an insulating support block 1 of a connector body A are embedded a plurality of contacts, each formed with a pressing slit 2a at a center of its tail 2, and oblique blades 2b on both sides thereof. A plurality of connection wires 3 are pressed into the pressing slits 2a of the tails of contacts by a cover B, so that the blades 2b of each of the contacts 2b are caused to penetrate into a coating 3a of the wire 3 so as to arrive into a core 3b of the wire 3. Thereafter, the connection wires 3 are further pressed into the pressing slits 2a of the tails 2 of the contacts, thereby connecting the wire 3 to the contacts of the connector. 
     As shown in FIG. 2a, the contact tails 2 are arranged in two rows and the contact tails 2 of each of the rows are arranged with minimum distances so that the connection wires 3 are able to be inserted into the pressing slits 2a without difficulty. Moreover, the pressing slit 2a of each contact tail 2B in the second row is arranged at a center between the pressing slits 2a of adjacent two contact tails 2A in the first row so that the contact tails 2A and 2B are arranged in a so-called &#34;staggered arrangement&#34; as shown in FIGS. 2a and 2b. It has been actually effected to make the length of the support block 1 as short as possible by making diameters D of the connection wires 3 and widths R of the contact tails 2 as small as possible. 
     However, there is a limitation for the reduction in diameter of wires and width of contact tails because of problems caused from electric current to be supplied and mechanical strength of the contact tails. For example, the contact tail is required to have mechanical strength to a certain extent for preventing any faulty connection of wires resulting from deformations of the oblique blades 2b in pressing the wires into the pressing slits 2a of the contact tails. It is actually difficult to make the diameter D of wires less than 0.3 mm and the width W of the contact tails less than 0.75 mm. Therefore, any particular idea is required for accomplishing further miniaturization of connectors. 
     SUMMARY OF THE INVENTION 
     It is a primary object of the invention to provide an improved small type connector which is more miniaturized in comparison with existing miniaturized connectors. 
     The subject matters of this invention lies in the following features. With a connector having contacts arranged staggered in two rows, a connection wire 3A to be connected to a contact tail 2A in a first row and a connection wire 3B to be connected to a contact tail 2B in a second row are arranged in directions reverse relative to each other downwardly toward contact tails to connected, respectively, as shown in FIG. 3a. Moreover, the connector body and the cover are provided with connection wire holding inclined surfaces whose inclinations are so determined that the connection wire 3B to be connected to the contact tail 2B in the second row is arranged above the uppermost end of the contact tail 2A in the first row and the connection wire 3A to be connected to the contact tail 2A in first row is arrange above the uppermost end of the contact tail 2B in the second row. 
     With this arrangement, connection wires 3A and 3B can be connected to contact tails without passing between contact tails 2B and 2A in the other row, thereby reducing distances 1 between the contact tails to a minimum possible distance without detrimentally affecting the insulation between wires as shown in FIGS. 3b and 3c. In this manner, a further miniaturization of connector is accomplished. 
     The invention will be more fully understood by referring to the following detailed specification and claims taken in connection with the appended drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIGS. 1a and 1b are explanatory views of a connector of the prior art; 
     FIGS. 2a and 2b are explanatory views of a connector of the prior art which was intended to be miniaturized; 
     FIGS. 3a, 3b and 3c are views for explaining the connector according to the invention; 
     FIGS. 4a, 4b and 4c are views illustrating a first embodiment of the connector according to the invention; 
     FIGS. 5 and 6 are explanatory views of a flat cable and a connector according to the invention using the flat cable; 
     FIGS. 7, 8a, 8b, 9a, 9b, 10a, 10b and 10c are views illustrating other embodiments of the connectors according to the invention; 
     FIG. 11 illustrates a comparative example of the support bases and push bases; 
     FIGS. 12 and 13a, 13b, 13c and 13d are views of a further embodiment of the connector according to the invention; and 
     FIGS. 14a and 14b are perspective views illustrating the connector shown in FIG. 12. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIGS. 4a and 4b illustrating one embodiment of the invention are a perspective view of a non-pierced condition and a sectional side view of pierced condition. FIG. 4a illustrates a connector body A made of an insulating contact support block 1, contact tails 2A and 2B in first and second rows, and first and second support bases 4A and 4B for obliquely arranging connection wires. The first and second support bases 4A and 4B are alternately arranged. The first support base 4A has an inclination directing downwardly toward the contact tails 2A in the first row, while the second support base 4B has an inclination directing downwardly toward the contact tails 2B in the second row. Moreover, the inclinations of the first and second support bases 4A and 4B are so selected that surfaces of the first and second support bases 4A and 4B corresponding to uppermost ends of the contact tails 2A and 2B in the first and second rows are located above the uppermost ends of the contact tails 2A and 2B. Reference numeral 5 denotes locking protrusions&#34; 
     In FIG. 4a, a cover B comprises an insulating block 6 having positioning walls 6a for positioning the cover B relative to the connector body A, and U-shaped locking members 7 adapted to be engaged with the locking protrusions 5 of the connector body A. First and second push bases 8A and 8B for obliquely arranging the connection wires are alternately arranged and have inclinations which are in parallel with and reversely inclined to that of the inclinations of the connector body A so that the connection wires are embraced between the inclinations of the connector body A and the cover B when the cover B is connected to the connector body A by means of the locking protrusions 5 and the U-shaped locking members 7. The cover B is formed with contact tail receiving grooves 9A and 9B for receiving the contact tails 2A and 2B when the cover B is connected to the connector body as shown in FIG. 4c. 
     The operation of the connector above described will be explained by referring to FIGS. 4a, 4b and 4c. 
     After the connection wires 3A and 3B have been arrange on the first and second support bases 4A and 4B of the connector body A as shown in FIG. 4b, the cover B is arranged and locked onto the connector body A such that surfaces of the inclinations of the first and second push bases 8A and 8B of the cover B are aligned with surfaces of the inclinations of the first and second support bases 4A and 4B of the connector body B and the contact tails 2A and 2B are brought into the contact tail receiving grooves 9A and 9B. As a result, the connection wires 3A are pressed into pressing slits 2a of the contact tails 2A in the first row so as to be connected to the contact tails 2A, while the connection wires 3B are pressed into pressing slits 2a of the contact tails 2B in the second row so as to be connected to the contact tails 2B as shown in FIG. 4c. Moreover, the connection wires 3A are positioned above the uppermost ends of the contact tails 2B in the second row and the connection wires 3B are positioned above the uppermost ends of the contact tails 2A in the first row, while these connection wires 3A and 3B are embraced and held between the support bases 4A and 4B and push bases 8A and 8B. 
     Therefore, the connection wires do not extend between the contact trails, so that distances between the contact tails can be shortened to accomplish the miniaturization of the connector. 
     Although the embodiment of the invention has been explained with the piercing connection of the multiplicity of single wires, the connector according to the invention can be applicable to a flat cable which, for example, comprises a number of bare wires 10 arranged in parallel with predetermined intervals and coated with a resin insulating material 11 to form a flat cable 12 as shown in FIG. 5. In this case, after the flat cable 12 has been arranged on the connector body A such that the bare wires 10 of the flat cable 12 are positioned on the support bases 4a and 4B, the cover B is forced onto the connector body A. As a result, the coating 11 between the bare wires 10 is pierced with the contact tails 2A and 2B so that the bare wires enter bottoms between the support bases 4A and 4B to be settled onto the inclinations of the connector body A and the cover B, whereby connection of the flat cable is established. 
     Another embodiment of the invention shown in FIG. 7 is quite different from the embodiment above described. In FIG. 7, a cover B is divided into two parts B 1  and B 2 , of which one B 1  is provided with first and second support bases 4A and 4B having contact tail passing-through apertures 13A and 13B and the other B 2  is provided with first and second push bases 8A and 8B having contact tail receiving grooves 9A and 9B. With this arrangement, after the cover parts B 1  and B 2  have been arranged one upon the other to fix connection wires, the cover parts B 1  and B 2  are covered on a connector body A such that contact tails 2A and 2B embedded in the connector body A are inserted into the contact tail passing-through apertures 13A and 13B, whereby a piercing connection is established. 
     In this case, moreover, the connector body A and the cover part B 1  of insulating blocks may be previously connected together as a unitary body to form the connector body A in the first embodiment so that this embodiment becomes substantially the same as the first embodiment. 
     In the above embodiments, the surfaces of the support bases 4A and 4B and push bases 8A and 8B for arranging the connection wires are substantially flat so that there is a risk for the connection wires to fall from the surfaces of the support bases 4A and 4B into the bottoms between the support bases when the connection wires are pushed by the push bases 8A and 8B. Therefore, the proper connection cannot be often accomplished. 
     Embodiments shown in FIGS. 8a and 8b serve to overcome such a problem. In FIG. 8a, connection wire positioning recesses 4A 1 , 4B 1 , 8A 1  and 8B 1  are provided in the proximities of the uppermost portions of the inclined surfaces of the support bases 4A and 4B and/or the push bases 8A and 8B. In FIG. 8b, elongated supporting grooves 4A 1 , 4B 1 , 8A 1  and 8B 1  are provided along the inclinations of the support bases 4A and 4B and/or the push bases 8A and 8B. 
     In the connection wire positioning recesses or the elongated supporting grooves, uppermost ends of the inclination surfaces may be chamfered to prevent wires from being damaged by sharp edges of the uppermost ends of the inclination surfaces. 
     In case of flat cables, moreover, the support bases 4A and 4B and the push bases 8A and 8B are provided at their highest portions with triangular or semicircular piercing assisting projections 4A 2 , 4B 2  and 8A 2 , 8B 2  so that torn lengths of the coating 11 of the flat cable 12 are made much longer in order to make easy the piercing by contact tails as shown in FIGS. 9a and 9b. 
     Although the above embodiments have been explained with the contacts having the U-shaped contact tails, the invention is applicable to other conventional contacts, for example, a contact having a tubular tail formed with a pressing slit 2a as shown in FIGS. 10a, 10b and 10c. 
     Moreover, the inclination surfaces of the support bases 4A and 4B and push bases 8A and 8B may be like steps as shown in FIG. 11 although they are not preferable. When the inclination surfaces are in the form of steps, connection wires 3 are folded along the steps so that the wires are pulled by folded lengths of the wires. Therefore, there are risks for contact tails to be subjected to tensile forces or deformed or for connection wires to be damaged. 
     FIG. 12 illustrates a further embodiment. In the above embodiments, contact tails have been explained arranged in two rows. With the embodiment shown in FIG. 12, there are provided contact tails in four rows to form two groups respectively consisting of contact tails 2A 1  and 2A 2 , and 2B 1  ; and 2B 2 , so that the contact tails 2A 1  are arranged between centers of the contact tails 2A 2  in one group, and the contact tails 2B 1  are arranged between centers of the contact tails 2B 2  in the other group in staggered arrangement, respectively. 
     As shown in FIGS. 13a, 13b, 13c and 13d, alternately inclined support bases 3C and 3D are alternately arranged and the contact tails 2A 1  and 2A 2  are so fixed that centers of the contact tails are at the support bases 3D inclined in the same direction and the contact tails 2B 1  and 2B 2  are fixed so as to be shifted by a width of one of the support bases relative to the contact tails so that within the width of one contact tail are included the two support bases 3D inclined in the same direction and one support base 3C therebetween. 
     As shown in FIGS. 13a-13d, the inclinations and angles thereof of the support bases 3C and 3D are so determined that with respect to one connection wire, one contact tail to be connected to the wire is extended over one support base, but the other contact tails do not extend over the two support bases 3C and 3D. 
     A further modification is illustrated in FIGS. 14a and 14b, among which FIG. 14a is a perspective view of a connector body A and FIG. 14b is a perspective view of a cover B thereof. 
     In FIG. 14a, a contact support block 1 comprises locking protrusions 14A, support bases 3C and support bases 3D having inclinations inclined in reverse directions to those of the support bases 3C. Reference numeral 2 denotes contact tails. The tails 2A 1  and 2A 2  are fixed in the support block 1 in two rows and staggered such that one tail in one row is located between two adjacent tails in the other row and the tails 2B 1  and 2B 2  are also fixed in the support block 1 in two rows and staggered such that one tail in one row is located between two adjacent tails in the other row. Moreover, the tails 2A 1  and 2A 2  are shifted by the width of the support base relative to the tails 2B 1  and 2B 2 . Within a width of one of the contact tails 2A 1  an 2A 2  there are two support bases 3C inclined in the same direction and one support base 3D therebetween, while within a width of one of the contact tails 2B 1  and 2B 2  there are two support base 3D inclined in the same direction and one support base 3C therebetween. The inclinations and angles thereof of the support bases 3C and 3D are so determined that with respect to one connection wire, one pressing slit 2a of one contact tail to be connected to the wire is extended over one support base, but the other contact tails do not extend over two support bases. 
     In FIG. 14b, a cover B has U-shaped locking member 14B and push bases 3E and 3F inclined in directions reverse to those of the support bases 3C and 3D. The push bases 3E and 3F are formed with contact tail receiving grooves 5 for receiving the contact tails. After connection wires 3A and 3B have been arranged on the inclined surfaces of the support bases 3C and 3D of the connector body A, the cover B is covered and connected onto the connector body A by means of the locking protrusions 14A and the U-shaped locking member 14B such that the contact tails enter the contact tail receiving grooves 5. As a result, connection wires 3A and 3B are forced into the contact tail pressing slits 2a so as to be connected to the contacts and embraced between the support bases 3C, 3E, 3D and 3F to prevent the connection wires from removing therefrom. 
     With these arrangements, it is clear in comparison of FIG. 12 with FIGS. 3b and 3c that the longitudinal length of the connector is considerably reduced in case of the same width of connection wires. With connection wires used at present, the length of the connector is reduced to about one half. Moreover, the embodiment as shown in FIG. 12 is superior to that shown in FIGS. 4a and 4b without making thin the wall thickness of the support and push bases so that the embodiment shown in FIG. 12 can remove the difficulty in manufacturing such as drop of mold accuracy with the result that the practically useful small type insulation-piercing connector can be provided. 
     As can be seen from the above explanation, with the insulation-piercing connector having contact tails staggered in two rows capable of leading out connection wires arranged above contact tails arranged in opposition to contact tails to which the wires are connected, so that distances between the adjacent contact tails can be shortened in comparison with those of the prior art. As a result, the miniaturization of the connector can be accomplished which can eliminate the risk of the connection wires to be damaged caused by contacting of the wires with contact tails. 
     While the invention has been particularly shown and described with reference to preferred embodiments thereof, it will be understood by those skilled in the art that the foregoing and other changes inform and details can be made therein without departing from the spirit and scope of the invention.