DAISY CHAIN CONNECTOR

Abstract: Daisy chain connector comprises a dielectric housing (10) in which an electrical contact assembly (40) is secured. Contact assembly (40) comprises identical contact sub-assemblies (40a,40b), each contact sub-assembly including electrical contacts (30) having contact sections (31) in alignment with apertures (11a) in a front surface of the housing and terminating legs (32,33) for electrical connection with signal conductors (51b) and ground conductors (51a) of electrical cables (50). Contacts (30) include contact plates (30a,30b) in engagement between contact sections (31) and legs (32,33) defining bifurcated pairs of legs for each contact (30) so that the signal conductors (51b) of one of cables (50) are respectively connected to one of legs (32,33) and the signal conductors (51b) of the other of the cables (50) are respectively connected to the other of legs (32,33) and at least one of legs (32,33) is part of ground bars (35) to which ground conductors (51a) are connected.

Description: This invention is related to an electrical connector for a cable assembly which is used for data transmission in an apparatus for information processing, such as a computer, and more precisely, a connector which can be used for a daisy chain cable assembly in which a plurality of connectors are connected in series by electrical cables. In an apparatus for information processing, such as a computer, the data being processed in this apparatus must be transmitted between individual parts, and various connection schemes have been used for this purpose. For example, as shown in Figure 13, connectors 2 are arranged on a mother board 1, and a daughter board 3 having various components arranged thereon is connected to each connector 2, thus, the transmission of data between each daughter board 3 is conducted through the mother board 1. However, a tremendous increase in the volume of data processing has occurred recently because of the higher density of the various components on the daughter boards 3, and this increased volume of data processing cannot be transmitted by the mother board 1 alone. For the above-mentioned reason, as shown in Figure 12, a cable assembly 4 is made by mounting connectors 6 onto both ends of a flat cable 5 having a plurality of conductors 5a, and this cable assembly 4 is electrically connected to connectors 3a,3b which are mounted at the ends of each of the daughter boards 3, as shown in Figure 13 thereby enabling data to be transmitted by the cable assemblies 4. In this case, when each daughter board 3 is successively connected by the cable assemblies 4, two connectors 3a,3b must be mounted on each daughter board respectively, as illustrated, and the problem arises of a decrease in the space on a daughter board for mounting the various components, which is caused by the increase in the number of connectors. Another example of a conventional connector for terminating flat multiconductor electrical cable is disclosed in document EP-A-0 023 936. In consideration of the above-mentioned problems, the object of this invention is to provide a connector for a cable assembly which is capable of forming a daisy chain connection by mounting only a single connector on each daughter board. According to one aspect thereof the present invention consists in an electrical connector for electrical connection to signal conductors and ground conductors of flat electrical cables, the connector comprising a dielectric housing in which rows of electrical contacts are secured, the contacts including receptacles in alignment with apertures in a front surface of the housing and terminating legs for electrical connection with the signal conductors and the ground conductors, characterized in that each of said contacts includes two contact plates, said plates defining by means of an overlying engagement, a pair of bifurcated legs at one side of each contact so that the signal conductors of one of the cables can be respectively connected to one of legs and the signal conductors of the other of the cables can be respectively connected to the other of legs; and in that at least one of legs is part of a ground bar to which a ground conductor is connected. In use of the connector each receptacle may be connected to an external terminal of a first external electric circuit board, for example, the legs being connected to ends of two different cables connected to second and third external electric circuit boards, for example. One of the legs of each contact may be connected to a first cable of the two different cables which is connected to the second external circuit board, and the other of the legs being connected to the second of the two cables which is connected to the third external circuit board, thus forming a daisy chain connection. Furthermore, the legs on one side of selected contacts among the plurality of contacts may be connected to the second external electric circuit board through the first cable, and the legs on the other side of the remaining contacts among the plurality of contacts being connected to the third external electrical circuit board through the second cable. Thus, the connection between the boards forming electric circuits can be made by mounting a single connector on each board. According to another aspect thereof the present invention consists in a method of making an electrical contact assembly, as defined in claim 6. For a better understanding of the present invention reference will now be made by way of example to the accompanying drawings, in which: FIGURE 1 is a perspective view of an example of the daisy chain connector of this invention. FIGURE 2 is a cross-sectional view of the above-mentioned connector in Figure 1 shown along the line II-II of Figure 1. FIGURE 3 is a front elevational view of a single contact as shown in Figure 2. FIGURE 4 is a cross-sectional view of the above-mentioned connector in Figure 2, shown along the line IV-IV of Figure 2. FIGURES 5 to 7 are perspective views showing the order of assembly forming the contact assembly. FIGURE 8 is a perspective view of the flat cable formed in a daisy chain cable assembly by use of the connector of this invention. FIGURE 9 is a front elevational view of an example of using the daisy chain cable assembly of Figure 8 to connect the daughter boards to form a daisy chain connection therebetween. FIGURE 10 is a perspective view of an alternative embodiment of the invention. FIGURE 11 is a cross-sectional view of the connector of Figure 10. FIGURE 12 is a perspective view of an example of connecting conventional connectors with flat cable forming a cable assembly. FIGURE 13 is a front elevational view of an example where the cable assembly of Figure 12 is used to form a daisy chain connection to connect daughter boards. Figures 1 and 2 show the daisy chain connector according to this invention. The connector 70 comprises a housing 10 made of a suitable insulating material and includes a pair of upper and lower matable housing sections 12,13, a pair of upper and lower cover sections 14,15, and an electrical contact assembly 40 described later which includes a plurality of contacts 30 and which is retained in the housing 10. Housing sections 12,13 are latchable together whereas cover sections 14,15 are latchable together onto housing sections 12,13. Cover sections 14,15 also provide strain relief for the flat electrical cables. Each contact 30 of the contact assembly has at one end a receptacle 31 to be connected directly with a terminal of an external electric circuit, and the receptacles are arranged in the housing 10 such that they face apertures 11a formed at the front wall 11 of the housing 10, the apertures being arranged in two rows in the lateral direction and with equal distances therebetween. The other end of the contact 30 is formed as a pair of bifurcated legs 32,33, as best seen in Figure 2 and as will be described later, and the ends of conductors 51 of two different flat cables 50 extending from other external electric circuits (not shown) are connected to respective legs 32,33. Among the conductors 51 shown in Figure 1, conductors 51a are the ground conductors which are connected to the legs of the contacts engaged with the ground terminals of the external circuits, and the conductors 51b are the signal conductors which are connected with the legs of the contacts engaged with the signal terminals of the external circuits. As can be seen from Figures 2 and 3, the contact 30 includes a contact plate 30a having the receptacle 31 at one end and a leg 33 at the other end, and a short tab plate 30b having a leg 32 only, and is formed by welding the tab plate 30b to the contact plate 30a at the middle portion of the contact plate 30a. The contact assembly is obtained by insert-molding a dielectric member 16 to a plurality of contacts which are arranged in an equally spaced relationship and in series. As indicated in Figure 2, the receptacles 31 of the contacts 30 are arranged in housings 12,13 in alignment with the two rows of the apertures 11a and the bifurcated legs 32,33 of each contact 30 extend upward within housings 12,13. Conductors 51 of the different flat cables 50 are connected to the bifurcated legs 32,33 and cable portions close to the conductors are fixed by being clamped between housings 12,13 and the covers 14,15. Since the two legs 32,33 and the receptacle 31 of each contact 30 are formed integrally as mentioned above, each conductor 51 of the different flat cables 50 connected with legs 32,33 is electrically connected to the terminal 61 of a circuit board 60 when board 60 is engaged with the connector 70. Thus a daisy chain connection with a pair of different flat cables 50 is formed by the single connector 70. Next, the process of manufacturing the contact assembly will be described with reference to Figure 5 to 7. First, as shown in Figure 5, a contact strip having the contact plates 30a, which include the receptacles 31 at one end and the legs 33 at the other end, and the tab plate 30b having the legs 32 only, arranged alternatively, is formed from a sheet of metal by stamping and forming. It should be noted that the receptacle 31 of each contact plate 30a is formed at this stamping stage so that, as can be seen from Figure 4, the receptacle 31 extends through the center line between the adjacent pair of legs 32 and 33. Next, dielectric member 16 shown with the double dotted line in Figure 5 is insert molded to the contact strip and subsequently the signal contact plates and the signal tab plates are detached from the ground bar 35 whereby a contact sub-assembly 40a is formed. In Figure 5, the left end contact plate and right end tab plate are used for the ground terminals, therefore, only the legs of the left end contract plate and the right end plate are connected with the ground bar 35, which is extended in the lateral direction at the rear end of the legs. The contact sub-assembly will be further described with reference to Figure 4. In Figure 4, in order to simplify the description, each receptacle is denoted as 31a,31b,31c..., and each leg as 32a,32b,32c..., and 33a,33b,33c..., commencing from the right. The contact plates 30a and the tab plates 30b formed by stamping which are of the same shape, respectively, are arranged alternatively and held in position in the dielectric member 16. It should be noted that legs 32a,33b,32b,33c,32c are arranged to correspond to the conductors 51b of the cable 50 and that the receptacles 31a,31b,31c..., extending from the legs 33a,33b,33c..., are displaced at the middle portion of the contact plates such that the receptacles extend through a center line between each pair of legs 32a and 33a, 32b and 33b, 32c and 33c..., respectively, toward the apertures 11a of the housing 12. Next, as shown in Figure 6 (the dielectric member 16 is not shown), the two contact sub-assemblies 40a,40b formed as described in Figure 5 are arranged back-to-back so as to face in opposite directions, and as shown in Figure 7 (the dielectric member 16 is not shown), the contact assembly is formed by welding both sub-assemblies at the middle portions of the contact and tab plates 30a,30b. In welding the sub-assemblies 40a,40b, they are arranged such that the contact plate 30a and the tab plate 30b of one sub-assembly correspond to the tab plate 30b and the contact plate 30a of the other contact sub-assembly and that the receptacles 31 of both sub-assemblies be in parallel and equidistant from each other so that the receptacles 31 face the respective apertures 11a of the housing 10 when the sub-assemblies are mounted in the housing. The engaged contact plates 30a with the respective tab plates 30b are then welded together. Then the signal conductors 51b of the flat cable 50 are connected to the legs of the signal contact plates 30a and the signal tab plates of the contact assembly 40, except for the leg 33a which is part of the ground plate 35 and the ground conductors 51a of the flat cable are connected to the ground bar 35. These connections are preferably done by welding. After the connection of the conductors 51a,51b of cables 50 to the contact assembly 40, the contact assembly is positioned in the housing 10 and thus the connector shown in Figure 1 is assembled. In the above mentioned embodiment, the welding for forming the contact assembly is made subsequent to the arrangement of the two contact sub-assemblies and before the connection of the flat cables, as shown in Figure 7. However, the welding need not be conducted at this stage. Namely, the welding for the two contact sub-assemblies may be conducted through the apertures 12a,13a of the housings 12,13 after the two connector assemblies connected to the flat cables 50 are assembled as shown in Figure 2. Thus, to formulate contact assembly 40 as shown in Figure 7, identical stamped and formed contact sub-assemblies 40a,40b have dielectric members 16 insert molded onto contacts 30 and legs 32 along legs 32,33 so that legs 32,33 to which signal conductors 51b are to be connected are separated from ground bars 35 except in the case of leg 33 remaining as part of ground bars 35. Dielectric members 16 maintain contacts 30 in position. Sub-assemblies 40a,40b are positioned back-to-back as shown in Figure 6 with dielectric members 16 in engagement as shown in Figure 3 so that tab plates 30a of legs 33 are positioned in overlying engagement with respective tab plates 30b of legs 32, whereafter the engaged tab plates 30a,30b are secured together as by welding. Figure 9 shows an example of the daisy chain connection in which a plurality of printed circuit boards are mutually connected by using the connector constructed according to the invention. A plurality of daughter boards 3 are connected to the mother board 1 through connectors 2 and the daughter boards 3 are connected to the connectors 70 through connectors 3C. The connectors 70 have flat cables 50 extending from and to the other connectors 70. Therefore, data signals transmitted through the flat cable 50 seen at the right end in Figure 9 are sent to the daughter board 3 located at the right end of the mother board, and at the same time, to the other daughter boards 3 successively by the connectors 70 connecting the flat cables 50 together in a daisy chain. In the above-mentioned embodiment, one of the bifurcated legs 32,33 of each contact 30 is connected to the conductor 51 of the flat cable 50 which is connected to the terminal of the second external electric circuit board and the other of the bifurcated legs 32,33 is connected to the conductor 51b of the flat cable connected to the terminal of the third external electric circuit boards, and, when the receptacles 31 are mated with the terminals 61 of board 60 of the first external electric circuit board, the first, second and third external circuit boards are electrically connected with each other through the contacts 30, whereby a daisy chain connection is established. However, in the arrangement shown in Figure 9, where the cables 50 can be arranged such that the signal conductors connecting the daughter board 3 at the left end with the daughter board 3 at the center portion on the mother board, are not connected to the signal conductors connecting the daughter board 3 at the center portion with the daughter board 3 at the right end thereon. Such an arrangement according to the invention will be described with reference to Figures 10 and 11. As shown in Figure 10, the contact assembly is the same as that described in regard to the embodiment of Figures 1-7. In Figure 10, in order to simplify the description, each receptacle of the upper row is denoted as 31a,31b, ---31k, in successive order from the right, and each leg of the upper row of the bifurcated legs is denoted as 32a,32b, ---32k (which are the legs of the tab plates 30b) and 33a,33b, ---33k (which are the legs of the contact plates 30a), also in successive order from the right. The connection between the upper row legs and conductors 51a,51b of the flat cable 50 of the upper side, will now be described with reference to Figure 10. The ground conductors 51a are connected to the ground bar 35, which extends in the lateral direction, and the signal conductors 51b are connected to the respective legs 33a,33b, ---33k of the contact plates 30a, in successive order from the right. In this embodiment, the ground bar 35 is arranged to connect with legs 33a and 33k of the contact plates 30a, and thus the receptacles 31a and 31k are mated with the ground terminals 61 of the board 60, and the remaining receptacles 31b,31c, ---31j are connected to the signal terminals 61 of board 60 as shown in Figure 11. In this arrangement, the first external electric circuit may be comprised of two different circuits. In such a case, the upper row receptacles are connected to one of the circuits and the lower row receptacles to the other of the circuits. Also, the signal conductors 51b of the lower side flat cable 50 are connected to the legs 33 of the contact plates 30a having the signal receptacles at the lower row and the ground conductors 51a are connected to the ground bar at the lower side of the contact. Namely, the flat cable 50 located at the upper side in Figure 10 is connected to the terminals 61a on the board 60 through the upper-row receptacles 31, and the flat cable 50 located at the lower side is connected to the terminals 61b on the board 60 through the lower row receptacles 31. By the above-mentioned arrangement, the two cables 50 can be connected independently to the board 3 through the single connector 70 so that the daisy connection between the flat cables is not provided. As explained above, according to the invention, as claimed the construction is such that a plurality of contacts are retained in the housing in two rows, each contact having at one end a first terminal which is engageable with the first external terminal of, for example, the first external circuit, and at the other end, a second terminal comprising bifurcated legs which are connected to the first and second cables which are connected to the second and third external circuits, respectively, and, thus, when the first terminal is connected to the first external terminal of the first external circuit, the first, second, and third external circuits are mutually and electrically connect so that a daisy chain connection is obtained. Also, by connecting the first cable to the bifurcated legs on one side of selected contacts among the plurality of contacts and the second cable to the bifurcated legs on the other side of the remaining contacts among the plurality of contacts, the first cable and the second cable can be connected independently to the third external circuit or two independent external circuits. Therefore, in the connection between the board defining the first external circuit, and two boards defining the second and third external circuits, for example, only a single connector need to be mounted on the board for the first external circuit, and thus a very small space for the connector on the board is needed. Therefore, a high density arrangement of various components on the board can be realized.

Claims: An electrical connector for electrical connection to signal conductors (51b) and ground conductors (51a) of flat electrical cables (50), the connector comprising a dielectric housing (10) in which rows of electrical contacts (30) are secured, the contacts including receptacles (31) in alignment with apertures (11a) in a front surface of the housing and terminating legs (32,33) for electrical connection with the signal conductors and the ground conductors, characterized in that each of said contacts (30) includes two contact plates (30a,30b), said plates (30a,30b) defining by means of an overlying engagement, a pair of bifurcated legs (32,33) at one side of each contact (30) so that the signal conductors (51b) of one of the cables (50) can be respectively connected to one of legs (32,33) and the signal conductors (51b) of the other of the cables (50) can be respectively connected to the other of legs (32,33); and in that at least one of legs (32,33) is part of a ground bar (35) to which a ground conductor (51) is connected. An electrical connector as claimed in claim 1, characterized in that said contact plates (30a,30b) correspond to different contact sub-assemblies (40a,40b). An electrical connector as claimed in claim 1, characterized in that dielectric members (16) are secured to said legs (32,33) maintaining said contacts (30) in alignment. An electrical connector as claimed in claim 1, characterized in that said housing (10) includes matable housing sections (12,13) and cover sections (14,15). An electrical connector as claimed in claim 4, characterized in that said housing sections have openings (12a,13a) in alignment with said engaged contact plates (30a,30b) so that the contact plates can be welded together through the openings (12a,13a). A method of making an electrical contact assembly (40) from identical stamped and formed contact sub-assemblies (40a,40b) each comprising a row of alternate contact elements and first legs (32), each contact element including a receptacle (31), a first contact plate (30a) and a second leg (33), the first legs (32) including second contact plates (30b), all the legs (32,33) in each contact sub-assembly (40a,40b) being attached to a ground bar (35); characterized by the steps of: inserting the legs (32,33) of each contact sub-assembly (40a,40b) into a dielectric member (16) moulding so as to hold the contact plates (30a,30b) and the first legs (32) thereof uniformly spaced with respect to each other; detaching the first and second legs (32,33) of each contact sub-assembly from the ground bar (35) leaving at least one of the legs (32,33) as part of the ground bar (35); and placing the contact sub-assemblies (40a,40b) in back-to-back relationship with the second contact plates (30b) of one of the sub-assemblies (40a,40b) in engagement with respective first contact plates (30a) of the other sub-assembly (40a,40b), to provide contacts (30) having bifurcated legs (32,33). A method as claimed in claim 6, characterized by the further step of welding together the engaged contact plates (30a,30b) of the sub-assemblies. A method as claimed in claims 6 or 7 characterized in that: in the step of placing said subcontact assemblies (40a,50b) in back-to-back relationship, said subcontact assemblies (40a,50b) are so placed that the receptacles (31) thereof are parallel to each other with said first and second legs (32,33) extending in parallel rows and being spaced at equal distances from said receptacles (31). A method as claimed in claim 6, 7 or 8, characterized by the step of: disponing said subcontact assemblies (40c,40b) when provided with said contacts (30) having bifurcated legs (32,33), in a dielectric housing (10) having a front wall formed with apertures (11a), with serial receptacles (31) in alignment with respective ones of said apertures (11a). A method as claimed in claim 9 characterized by the steps of: connecting electrical cables (50) to said signal contact plates (30a,30b), and mounting cover sections (15) on said housing (10) providing strain relief for said cables (50).

Inventors: KAMONO, TAKASHI, OHTSU, AKIHIKO
Applicants: THE WHITAKER CORPORATION
Application year: 1987
Main classification: H01R23
IPC codes: H01R12