Ribbon Cable Connector System Having Stress Relieving Means

Abstract

An improved ribbon cable connector for accurate and reliable connection of flat multiconductor electrical ribbon cable to other electrical components or subsystems. A plurality of flat conductive fingers embedded in a non-conductive medium are connected one each to a wire of the flat multi-conductor ribbon cable and encapsulated in a protective case which grips the ribbon cable so as to minimize stresses on the electrical connections.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates generally to electrical connectors, and more particularly to connectors designed for use with flexible multi-conductor cable having embedded therein a plurality of thin electrical conductors.

2. Description of the Prior Art

Flexible, flat multi-conductor cable comprised of a plurality of thin parallel wires longitudinally embedded in a thin flat belt-like insulating medium has been commercially available for a number of years. Such flat cable is particularly adapted for making economical electrical connections to high density closely arrayed circuit elements are as found in circuit boards and other electrical components of modern day computers. To effect such connections rapidly and economically a number of connectors and connecting systems have been devised. Some typical prior art devices are to be found in the U.S. Pat. Nos. having the following numbers: 3,508,187; 3,307,139; 3,034,091; 3,221,286; 3,319,216; 3,084,302; 3,131,017; 3,159,447; 2,932;810; 3,059,211, 3,407,374; 3,114,587.

Some reasons why flat ribbon cable connector systems have not found more extensive application, and particularly harness applications for interconnecting electrical components and circuits in the computer field, is the requirement for accuracy, consistency, and reliability.

In a present day computer system each electrical termination is identified and its position accurately known. Furthermore, rows of electrical terminals may be spatially stacked vertically one above the other, i.e. the electrical terminals of spatially stacked printed circuit boards. Each electrical terminal is associated with one wire, and a pair of wires is generally associated with one complete electrical circuit -- a live wire and a ground wire.

For the purpose of this invention the termination of a pair of associated electrical wires available for operatively coupling to other components, subcomponents, circuits or other similar terminations will be termed a port. When it is desired to interconnect rapidly one electrical terminal with another, and especially to connect each-to-each a plurality of electrical terminals, flat cable connectors may be effectively used. However, since each electric port may comprise at least two wires it is very important that a wire-to-wire correspondence be maintained for each terminal in the port. With prior art connectors such wire-to-wire correspondence is not always possible. For example, when a flat ribbon cable having two wires embedded one each on opposite surfaces of the cable, is used to connect two printed circuit boards disposed in vertical spatial alignment, the ribbon cable is bent in a U-shape and disposed such that the open ends of the U, face the wires they are to connect so that the wire on the upper surface of the cable forming one leg of the U is connected to the upper wire of the top circuit board. That same wire on the upper surface of the cable however becomes the lower wire embedded on the lower surface of the cable forming the other leg of the U -- physically the wire still remains embedded in the insulating medium in the same prior position, but its relative position changes. Hence, with such a prior art connection the top wire of one port of a top circuit boar could become connected to the bottom wire of another port of a bottom circuit board. Wherein a top-wire to top-wire connection is desired, a top-wire to a bottom wire can result.

Still another problem with prior art connectors is one of reliability. Since flat ribbon cable generally is comprised of a plurality of very thin wires embedded in an insulating medium, the wires are fragile and not capable of withstanding even ordinary stresses encountered with other types of electrical connecting systems, especially during the process of pulling the connectors apart.

SUMMARY OF THE INVENTION

Briefly, the invention herein disclosed comprises a ribbon cable connector system for accurate and reliable connection of flat multiconductor electrical ribbon cable to electrical circuits, components or subsystems.

A plurality of flat conductive fingers are embedded on either surface of a flat non-conductive medium, each finger having a portion of its area exposed and accessible for making surface-to-surface contact with other electrical conductors. Each of said fingers are also capable of soldered connection each-to-each with a plurality of thin wires embedded in a flexible ribbon-like electrically non-conductive medium. The combination is encapsulated in an electrically non-conductive housing having a predetermined curved portion for gripping the flexible ribbon cable, and relieving stresses especially during the process of pulling the connector out of its mating socket.

OBJECTS

It is an object therefore of the invention to provide an improved ribbon cable connector and system.

It is still a further object of the invention to provide an improved low cost, high density ribbon cable connector.

Still another object is to provide a ribbon cable connector having improved reliability.

Other objects and advantages of the invention will become apparent from the following description of a preferred embodiment of the invention when read in conjunction with the drawings contained herewith.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a pictorial representation of a front elevation of the ribbon cable connector system.

FIG. 2 is an exploded diagram of the ribbon cable connector system.

FIG. 3 is a schematic diagram of the ribbon cable connector system.

FIG. 4 is a partially explosed cross-section of the invention.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

Referring now to FIG. 1 a plurality of flat conductive fingers 3 are shown embedded on one surface of a flat non-conductive medium or wafer 4 each finger having one of its surfaces exposed. Similar non-conductive fingers 3 are also embedded on the opposite face of the flat non-conductive medium 4. A non-conductive housing 2 encloses a portion of the embedded electrically conductive fingers 3, the actual joint between the conductive fingers 3 and the plurality of wires of ribbon cable 1 further encloses and firmly grips a portion of ribbon cable 1. A serrated handle 6 with serrations 6.1 thereon provides a means for firmly gripping the unit when extracting it or inserting it in female connector 102. The female connector 102 has a plurality of receptacles along two of its edges 9 and is adapted to receive the plurality of flat conductive fingers 3 in registered interlocked engagement as shown in FIG. 1 on the right side of female connector 102. Notch 8 on the housing 2 of male connector 101 engages a resilient protrusion 7 which locks the male and female connectors together. The locking portion of the resilient protrusion 7 is rounded to permit ease of disengagement when an axial force is applied for separating said female and male connector. A space 9 devoid of any material is left between one pair of adjacent fingers and acts as a key in order that male connector 101 be inserted into the receptacles of female connector 102 having the proper relationship therewith.

Referring now to FIG. 2 details of the ribbon cable connector system are shown in an exploded view. A plurality of flat conductive fingers 3 fashioned from material such as aluminum, copper, gold, or silver which has good electrical conducting properties, are embedded on a portion of either or both surfaces of the wafer of predetermined shape and comprised substantially of a flat, substantially rigid, electrically non-conductive medium 4. It will be understood that the plurality of conducting fingers 3 may also be plated on a flat non-conducting medium 4 by techniques well known in the plated circuit board art and utilized to produce printed circuit boards. The conductive fingers 3 are disposed in parallel rows which extend transversely along the front edge of wafer 4. Each finger on either face of wafer 4 extends in parallel configuration rearward from the front edge to a position roughly midway between the front edge and the rear edge of wafer 4. The electrical path of each finger is continued toward the rear edge of wafer 4 by means of conductive connections 11 which may be plated on the surface of wafer 4. The conductive connections 11 provide not only a continuous electrical path for each finger from the front edge to the rear edge of the wafer but it also provides for compressed transverse dimensions of the electrical path of the fingers as they emerge at the rear edge of the wafer so that there is a one-to-one registration between cable wires and connector paths where the small wires 10 of ribbon cable 1 are permanently joined to the male connector. Electrical connection between the wires 10 and conductive paths 11 is effected by removing a portion of the insulation medium at the terminal end of the ribbon cable to expose a portion of each of the embedded wires and joining one each of the wires by soldering or other bonding means to one each of the conductive paths on the rear edge of the wafer. A non-conductive housing to protect the joints between wires 10 and conductive interconnections 11 is formed by bringing the two halves of the housing 2 together in correspondence one with the other and bonding the two casings together by compatible bonding techniques such as, for example, a thermal compression welding technique.

The female connector is typically assembled from two non-conductive mouldings or bodies made of plastic or other suitable non-conductive material. Each body 5 has a plurality of electrically isolated recesses 12 on one face of each body 5 extending inward from each edge. Spacer elements 13 provide the correct spaced relationship between bodies to form a receptacle at either end for receiving the male portion of the male connector 101. Inserted in each recess 12 of each body 5 are conductive resilient members 14 and 15.

Hence, when the two bodies 5 are brought together in registered alignment and joined by means of bolts 16 or other suitable joining means, a female connector 102 is formed having at least two receptacles at opposite edges for receiving the male portion of connector 101, and also having a plurality of open ended channels formed by the recesses 12 terminating on either edge of said female connectors 102 and with each open ended channel containing therein a pair of resilient members 14 and 15 extending from edge to edge. It will be noted that resilient members 14 and 15, which may be constructed from any suitable electrically conductive spring material such as berrylium copper each having at either end, toe sections in transverse relation to the longitudinal dimension, intermediate sections at either side of the center section in conjugate inverse lateral displacement relative to each other and a center section are assembled in each recess 12 in the form of an X. Each resilient member 14 and 15 of the X structure is electrically isolated from the other by having the cross-over point at the center section of the X structure, smaller in dimensions than the main body of the X structure and by displacing the center section of each finger 14 or 16 laterally from the longitudinal center. Pairs of resilient members are assembled in each recess so that the center section complements one another in position, i.e. one resilient member 15 has its center section raised relative to the other member 14, thus leaving a space at the cross-over point. (For ease of manufacture of members 14 and 15 both are identical; they differ however in assembly in that one is turned over so that its cross-over point complements in position the cross-over point of the other member).

When the several components are assembled as shown in FIG. 1, each one of fingers 3 of the male connector will slidably insert between resilient members 14 and 16 at either end. When two male connectors 101 are inserted into either edge of the opening of female connector 102 an edge schematic view would appear as shown in FIG. 3. A and B and also A' and B' represent wires on either face of a ribbon cable. It will be noted that wire A is on a top face whereas A WIRE A' is on a bottom face. When the male connectors are inserted into the female connectors an electrical contact is made between the wires on the respective faces of ribbon cable 1, the wires on the A face of one ribbon cable is connected to the wire in A' face of another ribbon cable. Thus, it will be observed that electrical connection is made between wires on opposite faces of separate ribbon cables. As hereinabove discussed, this feature permits accurate connection of desired terminals within a port particularly when connecting components in spaced parallel vertical alignment. It will of course be understood that said wires may also be in one plane and by bending the ends of each wire sequentially in alternate directions -- one up and the next one down, and so on -- the same effect is achieved as if the wires were on separate planes as herein discussed.

Referring now to FIG. 4 a plurality of conductive fingers 3 on either surface of a non-conducting wafer 4 are connected each to each by wires 11 to exposed wire portions 10 of conductive wires embedded within a flat ribbon cable 1. A non-conductive housing 2 comprised of a left half and a right half envelops and protects the connections and a portion of ribbon cable 1. Each half of the housing has an envelope section for enclosing the connections and a portion of the wafer with a plurality of embedded wires therein, and an S-curve section 21. When the two halves of the housing are aligned and joined together S-curves 21 interior to the housing fit together in coordinated engagement crimping the ribbon cable 1 to the same configuration and firmly holding it thereinbetween. Any force which is applied in any direction on the ribbon cable 1 external to the housing is absorbed within the configuration of the curve 21 and is not transmitted to the joints of wires 10 and 11.

Having shown and described one embodiment of the invention, those skilled in the art will realize that many variations and modifications can be made to produce the described invention and sill be within the spirit and scope of the claimed invention.

Claims

I claim:

1. An electrical ribbon cable male connector for connection to a flat, flexible ribbon-cable comprised of a plurality of longitudinally oriented substantially parallel flexible conductive wires embedded in a thin flat belt-like insulating medium and having a portion of the insulating medium at the terminal end removed to expose a portion of each of the embedded wires, said electrical ribbon cable male connector comprising:

a. a wafer of predetermined shape and comprised substantially of a flat non-conductive medium;

b. a plurality of flat electrically conducted fingers affixed to a an array on either surface of said wafer, each of said plurality of electrically conductive fingers having three of its faces substantially embedded in said non-conductive medium and with its fourth face substantially exposed, each of said fingers further comprised of two sections each section having different lateral dimensions and with the first section having larger lateral dimensions than the second section, each of said fingers further being disposed of said wafer in parallel longitudinal relationship with each other for that portion of their longitudinal dimensions contained in said first section, and for the remainder of their longitudinal dimensions in said second portion converging toward constricted lateral dimensions in isolated independence one from the other;

c. and non-conductive housing means for enveloping a portion of said wafer, and that portion of said plurality of conductive fingers in said second section, and a portion of the ribbon-cable when connected to the plurality of conductive fingers, said non-conductive housing means including stress-relieving means for minimizing stresses on the embedded conductive fingers when connected to the conductive wires of the electrical ribbon cable.

2. An electrical ribbon-cable connector for connection to a flat, flexible ribbon-cable as recited in claim 1 wherein said non-conductive housing means is comprised of two mating halves, each half further comprising an envelope section and in S-curve section, said envelope section having at least two notches on two of its peripheral sides, said notches for receiving mating protrusions from a female connector, when present, for locking the male connector to the female connector, said S-curve section containing the stress-relieving means, said S-curve section having lateral dimensions of the envelope sections, said lateral dimensions of said S-curve section flaring curvedly outwardly front to rear along the longitudinal access of S-curve section forming a curved flared grip-handle said curved flared grip-handle forming at least two cradles on its lateral periphery where said flared curved grip-handle joins said envelope section, whereby a thumb and forefinger may be cradled in each cradle respectively for ease in inserting or extracting said male connector into a female connector when present, said halves of said housing joined in mating alignment with the envelope sections enveloping a portion of said wafer and plurality of conductive fingers embedded therein and said S-curve sections in coordinated engagement with the flat ribbon cable when present thereinbetween.

3. An electrical ribbon-cable connector for connection to a flat, flexible ribbon-cable as recited in claim 2 further including on S-curve section lateral serrations on said flared curve handle means for firmly gripping said handle means with substantially no slippage when inserting or extracting said male connector into a female connector when present.

4. An electrical ribbon-cable connector for connection to a flat, flexible ribbon-cable as recited in claim 3 wherein a portion of said wafer with said plurality of conductive fingers affixed thereto protruding longitudinally beyond the envelope section of said non-conductive housing and including a section on a predetermined position of said protruding wafer devoid of any material therein for keying said connector to other mating connectors.

5. An electrical ribbon-cable connector for connection to a flat flexible ribbon-cable as recited in claim 4 wherein the plurality of flat electrically conductive fingers affixed in substantially parallel array on either face of said wafer as plated thereon.

6. An electrical ribbon-cable male connector for connection to a flat, flexible ribbon-cable comprised of a plurality of longitudinally oriented substantially parallel flexible conductive wires embedded in a thin-flat belt-like insulating medium and having a portion of the insulating medium at the terminal end removed to expose a portion of each of the embedded wires, said electrical ribbon cable male connector comprising:

a. a wafer of predetermined shape and comprised substantially of a flat non-conductive medium, said predetermined shape of said wafer having a recess on its rear peripheral edge, said recess having a depth dimension equal to at least the length by which said embedded wires are exposed, said recess also having a length dimension substantially equal to the width of the flat, flexible, ribbon cable;

b. a plurality of flat electrically conductive fingers affixed on either face of said wafer, each of said plurality of electrically conductive fingers having 3 of its faces substantially embedded in said non-conductive medium and with its fourth face substantially exposed, each of said fingers further being disposed on said wafer and parallel longitudinal relationship with each other for a portion of their longitudinal dimensions, and for the remainder of their longitudinal dimensions converging toward constricted lateral dimensions and isolated independent ones from the other;

c. in non-conductive housing means comprised of two mating halves, each half further comprising an envelope section and an S-curve section said halves of said housing joined in mating alignment, with the envelope sections enveloping a portion of said wafer, the portion of said wafer and conductive fingers thereon not enveloped by said envelope section protruding longitudinally forward of said envelope section, and with said S-curve section in coordinated engagement with the flat ribbon-cable when present thereinbetween.

7. An electrical ribbon-cable connector system comprising:

a. a wafer of predetermined shape and comprised substantially of flat non-conductive medium, said predetermined shape of said wafer having a recess on its rear peripheral edge;

b. a plurality of flat electrically conductive fingers affixed on either surface of said wafer, each of said plurality of electrically conductive fingers having three of its faces substantially embedded in said non-conductive medium and with its fourth face substantially exposed, each of said fingers further comprised of two sections each section having different lateral dimensions and with the first section having larger lateral dimensions than the second section; each of said fingers further being disposed on said wafer and parallel longitudinal relationship with each other for that portion of their longitudinal dimensions contained in said first section, and for the remainder of their longitudinal dimensions in said second section converging toward constricted lateral dimensions in isolated independence one from the other, said first section of said fingers for providing mating engagement with a female connector when present, and said fingers in said second section providing a surface for bonding thereto;

c. a flexible ribbon-cable comprised of a plurality of longitudinally oriented substantially parallel flexible conductive wires embedded in a thin flat belt-like insulating medium having a portion of the insulating medium at the terminal end removed to expose a portion of each of the embedded wires said exposed wires of said flexible ribbon-cable disposed, relative to the constricted end of said conductive fingers affixed to said wafer, in registered contacting alignment each-to-each and said wafer, in registered contacting alignment each-to-each and bonded one each-to-each at the contact points to the bonding surface;

d. and non-conductive housing means comprised of two mating halves, each half further comprising an envelope section and an S-curve section, said envelope section having at least two notches on two of its peripheral sides, said notches for receiving mating protrusions from a female connector, when present, for locking the male connector the the female connector, said S-curve section containing the stress relieving means, said S-curve section having lateral dimensions which are smaller than the lateral dimensions of the envelope sections, said lateral dimensions of said S-curve section flaring curvedly outwardly front to rear along the longitudinal access of the S-curve section forming a curved flared grip handle said curved flared grip handle forming at least two cradles on its lateral periphery where said flared curved grip handle joins said envelope section, whereby a thumb and forefinger may be cradled in each cradle respectively for ease in inserting or extracting said male connector into a female connector when present , said halves of said housing joined in mating alignment, with an envelope section enveloping a portion of said wafer, the portion of said wafer and conductive fingers thereon not enveloped by said envelope section protruding longitudinally forward of said envelope section, and with said S-curve sections in coordinated engagement with said flat ribbon-cable.

8. An electrical ribbon-cable connector system as recited in claim 7 further including on the lateral edges of said housing a notch of predetermined shape for accommodating a resilient protrusion when said electrical ribbon-cable connector is in cooperating unison with another connector having a resilient protrusion attached to its lateral edges, and wherein the recess contained in the shape of said wafer has a depth dimension equal to at least the length by which said embedded wires are exposed, said recess also having a length dimension substantially equal to the width of the flat, flexible, ribbon-cable.