Flat Cable Connectors Having Two Rows Of Contacts

Abstract

A connector for a flat cable has two opposed rows of contacts. The flat cable has signal conductors and a flat shield member which is terminated further from the end of the cable than the signal conductors. A row of signal contacts are crimped onto the signal conductors. The shield contacts extend beyond the signal contacts. The signal contacts can be crimped onto the signal conductors without making contact with the shield member. The shield contacts carry a shield connection through the connector for each signal conductor. In this way the impedance mismatch at the termination of the cable is reduced and impedance continuity through the conductor is improved.

Description

BACKGROUND OF THE INVENTION

This invention relates to connectors for flat cables and more particularly to a connector having two opposed rows of contacts for the signal conductors and the shield conductors.

Flexible flat conductor cables include cables having a plurality of flat ribbonlike conductors encased in an insulating film of polyester or other insulating material and ribbon cable which includes a plurality of round wires encased in insulation. In both types of cables, the axes of the wires are parallel and lie in a single plane.

U.S. Pat. Nos. 3,462,542 -- Richter and 3,459,879 -- Gerpheide show flat cables including a plurality of conductors and a plurality of flat shield strips. The flat strips of conductive material may be formed from a single piece of conductive material which has been stamped or etched so that only thin strips of material remain. This is shown in U.S. Pat. No. 2,370,846 -- Deakin.

Instead of using a plurality of flat shield members as shown in the aforementioned Richter patent and in FIG. 2 of the aforementioned Gerpheide patent it is common to use a single flat shield member. Such a flat shield member lying parallel to and spaced from all of the signal conductors is shown in FIG. 3 of the Gerpheide patent.

In flat cables having a continuous flat ground shield the termination of the cable sometimes presents a problem. In copending application, Ser. No. 57,244 filed July 22, 1970, Termination Means For Flat Cable, Homer Ernst Henschen, there is described and claimed a terminating connector which is inserted through the insulation to contact each signal conductor. A transverse zone on the shield member is devoid of electrically conductive material so that the terminal may be inserted through this zone to contact the signal conductor without contacting the shield member. A terminal can be crimped adjacent to this zone to provide contact with the shield.

The termination of cables presents problems because it often gives rise to discontinuities in the otherwise continuous impedance of the flat cable. These discontinuities at the terminating ends sometimes produce mismatch or signal reflections.

In our copending application, Ser. No. 099,194 filed Dec. 17, 1970, entitled FLAT SHIELDED CABLE, there is described a slit ground shield. By slitting the ground shield the capacitance between the signal conductors and the shield member is reduced thereby increasing the impedance of the cable. The characteristics are further improved by providing bridging strips across the transverse zone at the terminating end of the shield. These bridging strips improve the conductive characteristics of the shield member at the terminating end, thereby reducing the impedance mismatch at the termination end. While this has reduced the impedance mismatch to levels which are satisfactory for many applications, there are other applications in which the impedance mismatch at the termination of the cable must be improved still further.

SUMMARY OF THE INVENTION

In accordance with this invention a connector for a flat cable has contacts which carry a shield connection through the connector, one shield connection for each signal conductor in the flat cable. This greatly improves the impedance match at the termination of the cable. Impedance continuity is important in order to reduce crosstalk and prevent high standing wave reflections in high speed systems.

In accordance with the invention the connector has two opposed rows of contacts. The row of signal contacts enters one side of the flat cable and each contact is crimped to one signal conductor. The flat cable has a shield member which is terminated further from the end of the cable than the signal conductors. The shield contacts extend further from the end of the flat cable than the signal contacts. The shield contacts enter the other side of the flat cable and are crimped to the shield member.

The foregoing and other objects, features and advantages of the invention will be better understood from the following more detailed description and appended claims.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view of the flat cable, connector and mating plugs;

FIG. 2 shows the contacts and cable;

FIG. 3 is a top view of the cable partly cut away;

FIG. 4 shows a cross section of the cable and connector; and

FIG. 5 shows an enlarged cross section of the cable.

DESCRIPTION OF THE PREFERRED EMBODIMENT

This invention is a connector for a flat cable 10. The flat cable includes a plurality of signal conductors 12 and a shield member 14. As explained in our copending application the shield member is slit for impedance control. A dielectric 16 separates the signal conductors from the shield. Insulation 17 encases the cable. The shield member terminates at 18 which is further from the end of the cable than the signal conductor pads 20. Each of the signal conductors has an arcuate portion 22. The opposed arcuate portions of a pair of signal conductors provide room for the contacts to be crimped to the shield member without contacting the signal conductors.

The connector includes a nylon housing 24 having an open side 26 for receiving the flat cable.

The generally closed side 28, opposite the open side 26, has holes through which male plugs 30 are inserted.

The connector includes a row of signal contacts 32 and an opposed row of shield contacts 34. The row of contacts 32 extends transversely across the cable 10 and parallel to the open side 26 of the housing. The row of shield contacts 34 also extends transversely across the cable in a line parallel to the line of signal contacts. However, the shield contacts 34 extend further from the end of the cable than the signal contacts 32.

Each of the signal contacts 32 has an elongated flat web 36 which is positioned against the flat side of the cable. A pair of sidewalls 38 and 40 extend outwardly from the flat web. These side walls extend through the insulation 42 and are crimped over the signal conductor pad 20.

Similarly, each of the signal contacts 34 has a flat web portion 43 which is disposed against the other flat side of the cable. A pair of sidewalls, including sidewall 46, extend from the flat web and are crimped to the shield member 14 in the region 50. In this region 50 the signal conductors have arcuate sections 22 which provide room for the crimp to be made without contacting the signal conductors.

The signal contacts 32 are formed into a female receptacle 52 at the forward end of the connector. These female receptacles 52 are aligned with the holes in the generally closed side 28 of the nylon housing 24. Tabs 54 extend into the holes for alignment of the contacts with the connector housing.

Each of the shield contacts 34 is formed into a female receptacle which accommodates two male plugs. Tabs 56 at the forward end of the connector are used for alignment. Each of the shield contacts 34 provides two shield connections.

Various modifications will be suggested. In FIG. 3 the shield member is not terminated completely at the point 18. Rather, the shield member has a window 56 at the terminating end in a manner similar to that shown in our copending application to which reference was previously made. The shield contacts provide connections across the window 58 so the shield member is effectively terminated at the window. As shown, the shield member is terminated further from the end of the cable than the signal conductors. However, the reverse could be provided; that is, the signal conductors could be terminated further from the end of the cable than the shield member. It is only necessary that the signal conductors be terminated at a different distance from the end of the cable than the shield, or common, member.

Other modifications will be apparent and the appended claims are intended to cover all such modifications within the true spirit and scope of the invention.

Claims

What is claimed is:

1. A flat cable comprising:

a plurality of parallel spaced apart signal conductors lying in a single plane,

insulating material encasing said signal conductors to form a generally flat cable having two terminating ends, and

a common conductor lying in a plane parallel to the single plane of said spaced apart signal conductors, said common conductor being terminated at a different distance from the terminating end of said cable than said signal conductors,

a row of signal contacts extending transversely across said cable, and

a row of shield contacts extending transversely across said cable and generally parallel to said row of signal contacts, said signal contacts extending a different distance inwardly from the end of said cable than said shield contacts so that said signal contacts can be crimped on said signal conductors without contacting said common conductor.

2. The cable recited in claim 1 wherein said common conductor is a flat shield member.

3. The cable recited in claim 1 wherein said shield member is terminated at a point further from the end of each cable than said signal conductors, said shield contacts have two sidewalls extending from a web, said sidewalls being crimped to said shield member, the forward end of said shield contacts terminating in a female receptacle.

4. The cable recited in claim 1 further comprising a housing having an open side for receiving said flat cable.

5. A connector for a flat cable of the type including:

a plurality of parallel spaced apart signal conductors lying in a single plane,

insulating material encasing said signal conductors to form a generally flat cable having two terminating ends, and

a common conductor lying in a plane parallel to the single plane of said spaced apart signal conductors, said common conductor being terminated at a different distance from the terminating end of said cable than said signal conductors, said connector comprising:

a housing having an open side for receiving said flat cable,

a row of signal contacts, said row extending transversely across said housing and parallel to said open side,

a row of shield contacts, said row extending transversely across said housing and generally parallel to said open side, said shield contacts extending a different distance toward said open side than said signal contacts.

6. The connector recited in claim 5, wherein said signal contacts each have a pair of sidewalls extending outwardly from an elongated flat web positioned against the flat side of the cable, said sidewalls extending through said insulation and being crimped over one of said signal conductors, each of said shield contacts having a pair of sidewalls extending upwardly from an elongated flat web positioned against the flat side of the cable, said sidewalls extending through said insulation and being crimped to said common conductor.

7. The connector recited in claim 5, wherein said housing has a generally closed side with holes therein opposite said open side, the forward end of each contact being formed into a female receptacle with an opening disposed against said closed side so that male plugs can be inserted through said holes into the openings in said contacts.

8. The connector recited in claim 7, wherein the forward end of each contact has a tab which extends into one of the holes in the closed side of said housing for proper positioning of said contacts.

9. The connector recited in claim 5, wherein said signal contacts are opposed to said shield contacts so that said signal contacts can be inserted in one side of said flat cable and said shield contacts can be inserted in the other side of said flat cable.