Termination Means For Flat Cable

Abstract

Flat conductor cable has connecting means on one end comprising contact terminals disposed against one side of the cable with their forward ends in alignment with the end of the cable and with their axes parallel to the conductors. Each terminal is crimped, at its rearward end, through the cable and into electrical engagement with a conductor so that the surface of the cable supports the terminals. Cable end is contained in U-shaped housing having openings in its web to permit entry of complementary terminals. Where cable is shielded on one side, terminals are positioned on the unshielded side and shielding is removed on shielded side from the zone containing the crimped connections.

Description

BACKGROUND OF THE INVENTION

This invention relates to multi-contact connectors for flat cable such as the type of cable commonly referred to as flexible flat conductor cable the type referred to as ribbon cable, and similar types of cables. The phrase "flexible flat conductor cable" is generally understood to mean a cable having a plurality of flat ribbon-like conductors encased in an insulating film of polyester or other insulating material and ribbon cable comprises a plurality of round wires encased in insulation. In both types of cable, the axes of the wires are parallel and lie in a single plane. In the description and claims which follow, the term "flat cable" is employed in a generic sense and is intended to include the two types of cable referred to above as well as other types such as flexible etched circuits. The invention and its background are described below with particular reference to flexible flat conductor cable as a preferred embodiment.

Conventional flexible flat conductor cable comprises a plurality of parallel spaced apart conductors, which are ribbon-like as noted above, encased in an insulating film of Mylar (polyethylene terephthalate) or other polymeric material. Cables of this type are being used to an increasing extent because of their compactness, their superior electrical characteristics for certain applications, and because of the ease with which they can be placed in complex equipment.

The termination of flexible flat conductor cables and other flat cables has proved to be an obstacle to their more widespread usage because of the fact that conventional electrical connectors and terminals cannot be used on such cables and the specialized terminating devices which have been developed have been relatively expensive and can be applied only after extensive preparation of the cable end. For example, the removal of the insulating film from the end of a flexible flat conductor cable is a difficult and time consuming operation and the exposed conductors cannot be crimped or soldered in the conventional manner because of the fact that they are ribbons rather than round wires. Cables of this type are sometimes provided with a layer of shielding material on one side and the presence of this layer complicates the termination problem because of the fact that the shielding layer may not be electrically connected to the conductors. An additional problem related to the termination of shielded cables is that many of the previously available terminating techniques for flexible flat conductor cable do not permit maintenance of the shielding up to the end of the cable thereby resulting in an impedance discontinuity and a partial frustration of the purpose of the shielding.

The present invention is directed to an improved terminating means for flat cable, an improved terminal for such cable, and to an improved method of terminating flat cable. It is accordingly an object of the invention to provide an improved terminal for flat cable. A further object is to provide a termination for a shielded flat cable which permits maintenance of the shielding layer up to the terminated end of the cable. A still further object is the achievement of a low cost connector housing for flat cable. A further object is to provide an improved method for applying terminals and a connector housing to an end of a flat cable.

These and other objects of the invention are achieved in a preferred embodiment thereof which is briefly described in the foregoing abstract, which is described in detail below and which is shown in the accompanying drawings in which:

FIG. 1 is a perspective view of the end portion of a typical flexible flat conductor cable.

FIG. 2 is a view taken along the lines 2--2 of FIG. 1 showing a cross section of the cable.

FIG. 3 is a perspective view similar to FIG. 1 but illustrating the manner in which shielding material is selectively removed from the upper side of the cable to permit crimping of contact terminals onto the conductors of the cable.

FIG. 4 is a view taken along the line 4--4 of FIG. 3.

FIG. 5 is a perspective view of the end portion of a cable having a terminal crimped onto one of the conductors of the cable.

FIG. 6 is a sectional side view of a connector housing in accordance with the invention showing a cable end in alignment with the housing preparatory to insertion.

FIG. 7 is a sectional side view of a connector housing having the cable end received therein.

FIG. 8 is a view taken along the lines 8--8 of FIG. 6 and showing the transverse cross section of a crimped connection between a terminal and a conductor of the cable.

FIG. 9 is a perspective view of a terminated cable end having a housing thereon and illustrating the manner in which the socket terminals on the cable are coupled with complementary pin terminals.

FIG. 10 is a view similar to FIG. 5 illustrating the manner in which electrical contact is established with the shielding coating on cable.

FIG. 11 is a perspective view of the end portions of a cable having terminals thereon in accordance with an alternative embodiment of the invention.

FIG. 12 is a sectional side view of an alternative housing in accordance with the invention which is adapted to receive the cable of FIG. 11.

FIG. 13 is a sectional side view of a further alternative housing in accordance with the invention.

FIG. 14 is a perspective view of a terminated cable end having pin contacts thereon.

A typical flexible flat conductor cable 2 comprises a plurality of spaced-apart ribbon-like conductors 4 encased in a film 6 of suitable insulating material such as Mylar (polyethylene terephthalate). It will be understood that cables of this type are provided in varying sizes and with varying numbers of conductors, up to 30 conductors being provided in some cables for maximum density. The cable shown in FIG. 1 is provided with a layer 8 of metallic shielding material on its upper side which confers predetermined impedance characteristics on the conductors. The shielding material is usually covered by a thin film of insulation as indicated at 9. As will be explained more fully below, the principles of the instant invention are applicable to both shielded and unshielded cables but the invention is described with reference to termination of a shielded cable inasmuch as the problem is slightly more complex than the termination of an unshielded cable.

A terminal 10 in accordance with the invention has an elongated web 12 having a forward end 14, a rearward end 16, and an intermediate neck 17, the width of this web being substantially the same as that of the conductors 4 of the cable so that one terminal can be provided on one side of the cable for each conductor without having the terminals contact each other.

Opposed lances 18 are struck up from the rearward end 16 of the web and sidewall 20 extend upwardly from the longitudinal edges of this end of the web. These lances and sidewalls constitute a crimping means for establishing electrical contact with a conductor 4 of the cable as shown in FIG. 8 and as fully explained in the U.S. patent to Huffnagle 3,395,381. Specifically, the upper edges of the sidewalls 20 are forced through the film 6 on each side of a conductor and the sidewalls are then formed inwardly and downwardly until they capture the conductor between their edges and the upper edges of the lances 18. Electrical contact is established by virtue of these edges and the proximity of the sides of the conductor to the internal surfaces of the sidewalls as shown in FIG. 8. Crimped connections of this type may be formed with a suitable hand tool or with the aid of an automatic crimping machine of the general type shown in application Ser. No. 826,645, filed May 21, 1969, by Harold E. Cootes for Method and Apparatus for Terminating Cable.

The forward end 14 of the web has downwardly extending sidewalls 22 as viewed in the drawing from which arms 24 extend forwardly, these arms being directed inwardly then outwardly as shown at 26 so that they are adapted to receive a contact pin or blade between their opposed surfaces. A tongue extends centrally from the forward end or edge of the web 14 and functions to position the terminal in a connector housing of a type which will be described below.

When it is desired to terminate the end portion of the cable 2, the shielding material and the thin film of insulation 9 removed from a localized zone 30 extending transversely of the cable axis and spaced from the end of the cable by a distance substantially equal to the length of the forward end portion of the terminal. A terminal 10 can then be crimped onto each of the conductors 4 by positioning the terminal in alignment with a conductor, forcing the sidewalls 20 through the film 6 on each side of the conductor and finally forming the sidewalls inwardly and downwardly to produce the crimped connection shown in FIGS. 6 and 8 in accordance with the above-identified Huffnagle patent.

After application of the terminals to the conductors, the ends of the terminals will be in substantial alignment with the end of the cable and the tongues 28 will project for a slight distance beyond the cable end. The cable can then be inserted into a housing 32 comprising a relatively thick base or web 34 and parallel spaced-apart sidewalls 36, 38. A rib 40 is provided on the lower sidewall 38 and defines a leftwardly facing shoulder 42 which is adapted to lodge behind the rightwardly facing edges 43 of the sidewalls 22 of the terminals. Spaced-apart openings 44 are provided in the web 34 at locations corresponding to the locations of the terminals on the cable so that after insertion of the cable end, a terminal will be in alignment with each of the openings. Notches 46 are provided on the upper sides of the openings and are adapted to receive the tongues 28 of the terminals thereby to capture the terminated cable end and to prevent movement laterally of its axis within the housing, rearward movement of the cable being prevented by the previously described shoulder 42 of the rib 40.

FIG. 14 shows a terminated cable in accordance with the invention in which the terminals comprise contact pins 48 rather than sockets. Such pins can be formed by elongating and forming the side portions 24 of the terminal shown in FIG. 3.

It should be mentioned that the housing 32 can be manufactured either by molding or as a continuous extrusion, in which case the openings 44 would be formed by a simple punching operation. The sidewalls 36, 38 should be flexible outwardly and away from each other but should return to their normal positions after flexure to retain the inserted cable end. This housing may be of any desired insulating material such as nylon or polycarbonate so long as the material permits flexure of the sidewalls.

Where the cable is not shielded, that is, where it does not have the shielding layer 8 on its upper side, the terminals are simply crimped onto the conductors of the cable in the manner described above so that their ends are in alignment with the cable end.

A general advantage of the invention is that after application of the terminals to the conductors, the ends of the terminals are protected by the cable which supports the intermediate and forward portions of the web 12 as shown in FIG. 6. It is virtually impossible, unless gross mishandling and abuse are resorted to, to bend the terminals to the extent that they will be damaged because of the supporting effect of the cable end. A terminated cable in accordance with the invention does not have terminals extending beyond the cable and which can, by contrast, be easily damaged by even slight mishandling.

A further advantage of the invention, which is applicable to both shielded and unshielded cables, is the extremely low cost with which termination can be achieved. The housing 32 is of extremely simple shape and can be produced by low cost molding or extruding processes and the terminals can be applied to the cable end at extremely low cost by an automatic applicator of the type shown in the above-identified Cootes application.

In the case of a shielded conductor, it is a significant advantage that the shielding effect is maintained to the very end of the cable by virtue of the presence of the shielding material 8A on the lefthand side or the forward side of the area 30 from which shielding has been removed. By virtue of this fact, the characteristics of a cable having a predetermined impedance are virtually undisturbed at the end of the cable when it is terminated.

A completed termination in accordance with the invention as shown in FIG. 9 can be mated with complementary contact terminals 48 which may be mounted on the end of another cable or the end of a conventional round wire cable.

Under some circumstances, as where one cable is being electrically connected to another cable, it is desirable to electrically connect the ground plane 8 of the cable to the ground plane of the mating cable. As shown in FIG. 10, this can be done by simply leaving the shielding material on the upper side of the cable above one of the conductors 4 and crimping a terminal 20A onto this conductor and onto the shielding material. The same thing is done on the other cable; that is, a terminal is crimped onto one conductor and the shielding layer. When the connector 32 is then mated with the other connector, continuity of the shielding layer will be achieved through these and conductors in the two cables. In the event that a ground conductor is not provided in the cable, the terminals are simply crimped onto the shielding so that the shielding material on the two cables is electrically connected.

FIGS. 11 and 12 show an alternative embodiment of the invention in which alternate terminals 12 are positioned against the lower side of an unshielded cable 50 and the remaining terminals are positioned against the upper side of the cable. This arrangement will prove advantageous where the forward ends of the terminals are relatively wider than the terminals shown and would be too close to each other if they were all positioned against the same side of the cable. The housing 32' for the cable of FIG. 11 is similar in many respects to the housing 32 but has two rows of openings 44' which are staggered so that they will be in alignment with the terminals. Also a rib 40' must be provided on both of the sidewalls of the housing to retain the terminals on the upper and lower sides of the cable as shown in FIG. 12.

FIG. 13 shows a housing 32" in accordance with the invention having an internal wall 54 which is parallel to, and equidistant from, the sidewalls 36", 38" to define two recesses, each of which is adapted to receive a terminated cable as indicated. The housing of FIG. 13 can be produced as an extrusion or molding and can also be made by bonding two of the housings 32 to each other. A connector having more than two recesses is also within the scope of the invention.

Changes in construction will occur to those skilled in the art and various apparently different modifications and embodiments may be made without departing from the scope of the invention. The matter set forth in the foregoing description and accompanying drawings is offered by way of illustration only.

Claims

What is claimed is:

1. A shielded flat conductor cable having connector means on one end thereof, said cable comprising a plurality of spaced-apart parallel conductors lying in a single plane, said conductors being encased in a film of insulating material, one side of said film having a coating of metallic shielding material thereon, said connecting means comprising:

a terminal for each of said conductors, each of said terminals being disposed against the other side of said cable in alignment with its respective conductor and with its leading end in substantial alignment with said one end of said cable,

said cable being devoid of said coating in a zone spaced from said one end of said cable by a distance substantially equal to the length of one of said terminals, said zone extending transversely across said cable,

said terminals having trailing ends located on said other side of said cable opposite to said zone, said trailing ends having crimped means thereon extending through said cable and crimped onto said conductors,

channel shaped housing means having a web and sidewalls, said web having openings therein at spaced-apart intervals corresponding to the spacing between said conductors,

said end of said cable being between said sidewalls with said terminals in alignment with said openings and,

retaining means effective between said cable and at least one of said sidewalls for retaining said cable in said housing whereby,

said shielding means extends to the end of said cable and the ends of said terminals.

2. A method of applying terminals to the ends of conductors in a shielded flat conductor cable of the type comprising a plurality of parallel spaced-apart conductors encased in an insulating film, said film having a layer of metallic shielding material on one side thereof, said method comprising the steps of:

removing said metallic shielding material from a localized zone on said one side thereby to form a discontinuity extending transversely across said cable adjacent to one end thereof,

positioning a terminal member of the type having crimping means at its rearward end against the opposite side of said cable with said terminal extending parallel on one of said conductors, with the leading end of said terminal in substantial alignment with said one end of said cable, and with said crimping means opposite to said discontinuity,

forcing said crimping means through said film and crimping said crimping means onto said one conductor, and

similarly crimping a terminal member onto the remaining conductors in said cable.

3. A multi-conductor flat cable having connecting means on one end thereof, said cable comprising a plurality of spaced-apart conductors which are parallel to each other at said one end, said conductors lying in a single plane and being contained in insulating material, said connecting means comprising:

a terminal for each of said conductors, each of said terminals being disposed against said cable and extending parallel to its respective conductor, each terminal having a forward end located at said one end of said cable and each terminal having a rearward end which is mechanically and electrically joined to its respective conductor,

a generally channel-shaped housing comprising a web and sidewalls, said housing having aligned openings in said web at spaced-apart intervals corresponding to the spacing between said conductors,

said one end of said cable being between said sidewalls and against said web with said terminals in alignment with said openings, and

interengaging means effective between at least one of said sidewalls of said housing and said terminals for retaining said one end of said cable and said terminals in said housing whereby,

said housing contains said one end of said cable and said terminals, said terminals being engageable with complementary terminals thereby to electrically connect said conductors to said complementary terminals.

4. A terminated cable as set forth in claim 3 wherein all of said terminals are mounted on one side of said cable in side-by-side relationship.

5. A terminated cable as set forth in claim 4 wherein said cable has a layer of metallic shielding material on the side opposite to said one side, a transversely extending zone adjacent to said one end being devoid of said shielding material, said zone extending only partially across said cable, said rearward end of at least all but one of said terminals being crimped through said zone whereby at least all but one of said terminals are electrically isolated from said shielding material and said shielding material extends to said one end of said cable.

6. A terminated cable as set forth in claim 5 wherein one of said terminals is crimped onto said shielding layer.

7. A terminated cable as set forth in claim 5 wherein one of said conductors is a ground conductor, said shielding layer extending opposite to said one conductor, one of said terminals being crimped onto both said shielding layer and onto said one conductor.

8. A terminated cable as set forth in claim 4 wherein said interengaging means comprises an internal rib on one of said sidewalls, said rib defining a shoulder opposed to said web, said shoulder being in engagement with said terminals.

9. A terminated cable as set forth in claim 3 wherein said terminals comprise contact sockets.

10. A terminated cable as set forth in claim 3 wherein each of said terminals comprises an elongated flat terminal web portion disposed against said cable, each of said terminals being joined to its respective conductor by a crimped connection comprising a first pair of sidewalls extending laterally from said terminal web through said cable and being reversely bent into embracing relationship with the associated one of said conductors.

11. A terminated cable as set forth in claim 10 wherein said terminal webs of said terminals have contact means at their forward ends, each of said contact means comprising a second pair of sidewalls extending laterally from the edges of said terminal web away from said cable, said second sidewalls having formed portions for engagement with a complementary terminal.

12. A terminated cable as set forth in claim 11 wherein said formed portions comprise inwardly directed intermediate and outwardly directed end portions of said sidewalls whereby opposed surfaces of said sidewalls are adapted to receive said complementary terminal members therebetween.

13. A terminated cable as set forth in claim 10 wherein the said terminal web portion of each terminal has a forwardly extending central tongue integral with its leading end, each of said openings in said web being shaped to receive said tongue thereby to retain said cable against lateral movement with respect to said housing.

14. A terminated cable as set forth in claim 3 wherein said terminals are mounted on both sides of said cable.

15. A terminated cable as set forth in claim 14 wherein alternate ones of said terminals are on one side of said cable and the remaining ones of said terminals are on the other side of said cable.

16. A plurality of multi-conductor flat cables, said cables having connecting means on corresponding ends thereof, each cable comprising a plurality of spaced-apart conductors which are parallel to each other at one end, the conductors of each cable lying in a single plane and being contained in insulating material, said connecting means comprising:

a terminal for each of said conductors of each of said cables, each of said terminals being disposed against its respective cable and extending parallel to its respective conductor, each of said terminals having a forward end located at said one end of its respective cable and each terminal having a rearward end which is mechanically and electrically joined to its respective conductor,

an insulating housing comprising a web and a plurality of parallel sidewalls extending in a common direction from said web, a plurality of rows of aligned openings in said web, at least one of said rows of openings extending between each pair of adjacent sidewalls, the spacing between adjacent openings of said rows being the same as the spacing between said terminals on said cables,

each of said cables extending between an adjacent pair of said sidewalls with said one end of each cable substantially against said web and with said terminals in alignment with said openings, and interengaging means effective between said at least some of said sidewalls and said terminals of each of said cables for retaining said terminals and said cables in said housing.