GB2241391A - Earth continuity in electrical connector - Google Patents

Abstract

A miniature electric connector (1), for example a data jack, is used with a cable having an earth screen, and has a metal end fitting (not shown) connected to the screen. A resilient conductive clip (20) is preformed with flexible tail (21); the clip (20) resiliently engages the end fitting on the cable and the flexible tail (21) (which is preferably insulated) can be connected to a connector contact. <IMAGE>

Description

ELECTRIC CONNECTOR This invention relates to electric connectors, and more particularly to connectors of small size. Extremely compact designs of connector, often based on a monolithic plastics moulding, have become commonplace in the connection of telecommunication apparatus, and are generally satisfactory for use with telephone speech circuits, but if they are to be used successfully for data transmission the need to provide for screening against interference becomes apparent. For simplicity, such connectors, whether male or female, will be referred to hereinafter as "data jacks".

The present invention provides connectors of comparable dimensions that are screened and suitable for use with screened or fully-shielded cords and thus suitable for data transmission applications, for example in Local Area Networks. The connectors in accordance with the invention may inter alia, be cord-mounted plugs or sockets, panel-mounted sockets or wall mounted sockets.

This will entail the use of a cord with a braid or other earth screen, and in most cases it will be necessary to provide earth continuity though the connector by connecting the earth screen of the cord to one (or in extreme cases more than one, but not all) of the contacts of the connector.

The contact(s) to be used for this purpose will vary with the application of the connector, and it is therefore desirable to provide facilities whereby any chosen contact may be connected to the earth screen, and this is difficult within the small spaces available in suqh connectors.

In accordance with the present invention, å metal and fitting is applied to the cord and connected to its earth screen, and the connector includes a resilient conductive (preferably metal) clip pre-formed with a flexible tail, the clip resiliently engaging the said end fitting and the flexible tail being connected to a selected one of the connector contacts.

The flexible tail may be a narrow strip formed in one piece with the clip, or alternatively it may be a wire (or wire strand, or tinsel) conductor connected to it by crimping or in any other suitable way. In both cases, the flexible tail can be insulated if desired.

When the cord screen is a braid, the end fitting is preferably of the form described in another application (Agent's reference MJP/J0795) filed today.

The invention will be further described, by way of example, with reference to the accompanying drawings in which: Figure 1 an exploded view shoeing 5 parts of a cord mounted data jack in accordance with the invention separated form one another in correct vertical alignment; Figures 2, 3 & 4 are plan views of three of these members; Figure 5 is an end view of another member; Figure 6 is a diagramatic sectional view of a cord end prepared for connection to the data jack; Figure 7 is a diagramatic end view of the cord termination of figure 6; and Figures 8 & 9 are sketches of earthing accessories for use with the termination of figures 6 and 7.

Referring first to figures 1 to 5, the jack (which is designed to North American, rather than British, practice) comprises five separate mouldings all formed in a plastics material having a suitable small degree of flexibility; the components have been numbered from top to bottom for ease of reference to the drawing.

Component 3 (figures 1 and 3) is the main insulating component upon which are mounted contacts 6 having portions (at the right hand end as drawn) for making contact with the mating connector and (at the left hand end) insulation piercing formations for contacting conductors of an electric cord. Depending on design preference, component 3 may be a monolithic moulding or it may be a composite made of two (or more) mouldings welded or snapped together. This component 3 is trapped between two main screening components, 1 and 4, both of which are metallised all over, including their inner surfaces, and which snap fit together; spigots 7 and apertures 8 on components 4 and 3 respectively assist in precise location.The remaining members of the connector proper are an unmetallised, insulating "conductor stuffer" 2, which is first snap fitted inside component 1 as shown in dotted lines in figure 1, and which presses the cord conductor ends into effective engagement with the appropriate insulation-displacing contacts 6 when the parts are assembled, and eliminates any risk that a properly terminated cord conductor end might make electrical contact with the metallising on component 1, and a locking member 5 which is trapped between the insulating component 3 and the housing member 4, with a recess 9 providing precise location. This member 5 is unmetallised, not for any electrical reason but because repeated flexing in use might tend to cause unsightly flaking off of the metallisation.

Figures 6 and 7 show the way in which a wire braided cord is terminated for connection to the phone jack; the cable comprises (say) four insulated conductors 10 surrounded by wire braid 11 and enclosed in a plastics sheath 12. In preparation for termination, these parts are cut back to a appropriate distance in the usual way. A metal ferrule 13 is threaded over the cut-back cord end so that one of its ends is pushed onto the sheath 12 while its other end overlies the exposed part of the braid 11. The ferrule is a resilient push fit on the end of the sheath, and local detents 14 may if desired be provided to improve the grip and give a measure of security against tension.The ferrule is preferably of tapered or stepped internal diameter, to avoid leaving any substantial gap between it and the underlying part of the braid, and its external surface may be correspondingly stepped or tapered, for instance by making it of uniform wall thickness. The projecting end portion 15 of the braid 11 is next turned back to surround the end part of the ferrule 13, and an outer metal ring 16 is threaded over it and compressed with a crimping tool so that the braid is firmly gripped between the ring 16 and the ferrule 13. The ring 16 might be a simple circular one, but preferably it is formed with a pair of projecting lugs 17 (or at least one lug) since this provides a ready means of securing the cord end against tension and any tendency to rotation.Specifically, the lugs 17 may enter recesses 18 (figure 4) to provide the required location, and at the same time ensure adequate electrical contact between the cord braid and the metallising on components 1 and 4.

It will often be a requirement also to provide connection between the cord braid and one of the contacts 6, and this may be acheived using an auxillary component of the form shown in either figure 8 or 9. Figure 8 shows a one-piece metal clip having an end part 20 which is of suitable dimensions and resilience for gripping engagement either with one of the lugs 17 or with the main body of the ring 16 and a thin flexible projection 21 which can be bent by the installer to engage it with any selected one of the contacts 6. Two of these components can be used to provide earth connections on two of the conductors 6 if required. The alternative design in figure 9 is similar, except that the integral projecting finger 21 is replaced by a short length of insulated wire conductor 22, and is used in a substantially the same way.

Claims (7)

1. An electric connector mounted on the end of a cord having an earth screen in which a metal end fitting is applied to the cord and connected to the said earth screen and in which the connector includes a resilient conductive clip preformed with a flexible tail, the clip resiliently engaging the said end fitting and the flexible tail being connected to a selected one of the connector contacts.

2. A connector as claimed in claim 1 in which the said flexible tail is narrow strip formed in one piece with the clip.

3. A connector as claimed in claim 1 in which the said flexible tail is a wire, wire strand or tinsel conductor connected to the clip.

4. A connector as claimed in any one of the preceding claims in which the said flexible tail is insulated.

5. An electric connector substantially as described with reference to figure 8 of the drawings.

6. A connector as substantially as described in figure 9 of the drawing.

7. A connector as substantially as described with reference to figures 6,7 and 8 or 6,7 and 9 of the drawings.