Keyed fibre optic connector

A keying system for providing selective interconnection between a receptacle socket and a connector plug terminating an optic fibre, the connector plug adapted for insertion into the receptacle socket. The keying system comprises a raised boss configured to one of a plurality of predefined boss keying geometries and a cavity configured to one of a plurality of predefined cavity keying geometries. The boss is either in one of the receptacle socket or on a forward end of the connector plug and the cavity is formed in the other of the receptacle socket or the forward end of the connector plug. At least one of the predefined boss keying geometries matches at least one of the predefined cavity keying geometries. When the boss keying geometry matches the cavity keying geometry, the boss can be inserted into the cavity thereby interconnecting the connector plug with the receptacle socket. In this manner correct interconnections between connectors and other connectors or sockets can be insured thereby providing an enhanced level of security.

FIELD OF THE INVENTION

The present invention relates to a keyed fibre optic connector. In particular, the present invention relates to an interlocking connector and receptacle pair for fibre optic cables with a geometric keying system moulded into the interface thereby preventing connectors with a first key from being interconnected via a receptacle having a differing key.

BACKGROUND OF THE INVENTION

Optical fibres terminated by connectors and the receptacles which are adapted to received these connectors are an important part of virtually any fibre optic communications system. For example, such connectors and receptacles may be used to interconnect fibre segments to create longer lengths, to connect optic fibre to active or passive devices, etc. However, in some cases, for example for security reasons or in order to better manage a telecommunications network, it is desired to physically limit the insertion of a connector plug into a particular receptacle socket, and as a result prevent the transmission of data via that connector plug and receptacle socket.

The prior art reveals a variety of systems for preventing a connector plug from being inserted into a receptacle socket. One of these prior art systems comprises at least one tab arranged at a certain position on the connector plug, each of which is adapted for insertion into a corresponding tab receiving indentation moulded in the receptacle socket. In the absence of such a hollow the tab buts against the opening of the receptacle socket, thereby preventing the connector plug from being completely inserted into the receptacle socket, thereby preventing the connector plug from being correctly interconnected with the receptacle socket. One drawback of these prior art designs is that that the tab, being typically moulded into the plastic connector plug housing, can be easily removed by filing or using a sharp blade or the like. Another drawback is that such prior art designs only allow two types of connector plugs to be differentiated between: connector plugs with a tab and connector plugs without a tab.

The prior art also reveals keying systems such as the U.S. patent application Ser. No. published with the No. 2002/0126960 A1 comprising a connector plug and receptacle socket. Interconnection of the connector plug and receptacle socket is limited to connector plug/receptacle socket pairs where a key within the receptacle socket mates with a corresponding key receiving slot in the connector plug. A connector plug with a key receiving slot in one position is unable to interconnect with receptacle sockets with a differently positioned key. As a result, by providing a number of differently positioned keys and key receiving slot a system of selective interconnection between connector plugs and receptacle sockets can be arrived at. These systems, however, are generally impractical in many fibre optic systems given the relatively small size of the connector plug and the receptacle socket.

SUMMARY OF THE INVENTION

In order to address the drawbacks of the prior art, there is provided a keying system for providing selective interconnection between a receptacle socket and a connector plug terminating an optic fibre, the connector plug adapted for insertion into the receptacle socket. The keying system comprises a raised boss configured to one of a plurality of predefined boss keying geometries and a cavity configured to one of a plurality of predefined cavity keying geometries. The boss is either in one of the receptacle socket or on a forward end of the connector plug and the cavity is formed in another of the receptacle socket or the forward end of the connector plug. At least one of the predefined boss keying geometries matches at least one of the predefined cavity keying geometries. When the boss keying geometry matches the cavity keying geometry, the boss can be inserted into the cavity thereby interconnecting the connector plug with the receptacle socket.

There is also provided a receptacle for providing selective interconnection with a connector plug terminating a first optic fibre, the connector plug comprising a cavity having a connector keying geometry formed in a forward end thereof. The receptacle comprises at least one receptacle socket comprising a raised boss therein, the boss having a shape corresponding to one of a plurality of predefined receptacle keying geometries, the connector keying geometry corresponding to one of the predefined receptacle keying geometries. When the receptacle keying geometry corresponds to the connector keying geometry, the connector plug can be inserted into the receptacle socket.

Furthermore, there is provided a receptacle for providing selective interconnection with a connector plug terminating a first optic fibre, the connector plug comprising a boss having a connector keying geometry formed in a forward end thereof. The receptacle comprises at least one receptacle socket comprising a cavity formed therein, the cavity having a shape corresponding to one of a plurality of predefined receptacle keying geometries, the connector keying geometry corresponding to one of the predefined receptacle keying geometries. When the receptacle keying geometry corresponds to the connector keying geometry, the connector plug can be inserted into the receptacle socket.

Additionally, there is provided a connector terminating an optic fibre for providing selective interconnection with a receptacle socket, the receptacle socket comprising a raised boss having a receptacle keying geometry formed therein. The connector comprises a connector plug adapted for insertion into the receptacle socket and comprising a cavity, the cavity having one of a plurality of predefined connector keying geometries formed in a forward end thereof, the receptacle keying geometry corresponding to one of the predefined connector keying geometries. When the receptacle keying geometry corresponds to the connector keying geometry, the connector plug can be inserted into the receptacle socket.

Also there is provided a connector terminating an optic fibre for providing selective interconnection with a receptacle socket, the receptacle socket comprising a cavity having a receptacle keying geometry formed therein. The connector comprises a connector plug adapted for insertion into the receptacle socket and comprising a boss having one of a plurality of predefined connector keying geometries formed in a forward end thereof, the receptacle keying geometry corresponding to one of the predefined connector keying geometries. When the receptacle keying geometry corresponds to the connector keying geometry, the connector plug can be inserted into the receptacle socket.

Furthermore, there is provided a system for providing selective interconnection between first and second optic fibres. The system comprises a receptacle comprising back-to-back receptacle sockets, each of the sockets comprising a raised boss disposed therein and configured to one of a plurality of predefined receptacle keying geometries, a first connector plug terminating the first optic fibre, the plug adapted for insertion into a first of the back-to-back receptacle sockets and comprising a cavity formed in a forward end of the plug, the cavity configured to one of a plurality of predefined connector keying geometries, and a second connector plug terminating the second optic fibre, the plug adapted for insertion into a second of the back-to-back receptacle sockets and comprising a cavity formed in a forward end of the plug, the cavity configured to one of a plurality of predefined connector keying geometries. At least one of the predefined connector keying geometries matches at least one of the predefined receptacle keying geometries and when a receptacle keying geometry of a boss of a first of the back-to-back receptacle sockets corresponds to the connector keying geometry of the first cable and a receptacle keying geometry of a boss of a second of the back-to-back receptacle sockets corresponds to the connector keying geometry of the second cable, the first cable can be inserted in the first socket and the second cable can be inserted in the second socket bringing the first optic fibre into axial alignment with the second optic fibre.

Additionally, there is provided a receptacle for providing selective interconnection between first and second fibre optic cables, each cable comprising a connector plug comprising a cavity having a connector keying geometry formed in a forward end thereof. The receptacle comprises back-to-back receptacle sockets, each of the sockets comprising a raised boss, the boss having a shape corresponding to one of a plurality of predefined receptacle keying geometries. Each of the connector keying geometries corresponds to one of the predefined receptacle keying geometries and when the receptacle keying geometry of the boss of a first of the back-to-back receptacle sockets corresponds to the connector keying geometry of the first cable and when the receptacle keying geometry of the boss of a second of the back-to-back receptacle socket corresponds to the connector keying geometry of the second cable, the connector plug of the first cable can be inserted in the first socket and the connector plug of the second cable can be inserted in the second socket, thereby interconnecting the first and second cables.

There is also provided a field-configurable receptacle for providing selective interconnection with a connector plug in a fibre optic communications system, the connector plug comprising a connector keying geometry formed in a forward end thereof. The receptacle comprises at least one receptacle socket adapted for receiving the connector plug and comprising a configurable shape, the shape corresponding to one of a plurality of predefined receptacle keying geometries. The he connector keying geometry corresponds to one of the predefined receptacle keying geometries and when the shape is configured to correspond to the connector keying geometry, the connector plug may be inserted into the socket.

In addition, there is provided a field-configurable connector for providing selective interconnection with a receptacle in a fibre optic communications system, the receptacle comprising at least one receptacle socket having a receptacle keying geometry formed therein. The connector comprises a connector plug adapted for insertion into the receptacle socket and comprising a configurable shape corresponding to one of a plurality of predefined connector keying geometries. One of the predefined connector keying geometries corresponds to the receptacle keying geometry and when the receptacle keying geometry corresponds to the connector keying geometry, the connector plug can be inserted into the receptacle socket.

DETAILED DESCRIPTION OF THE ILLUSTRATIVE EMBODIMENTS

Referring now toFIG. 1, a fibre optic connector in accordance with an illustrative embodiment of the present invention will be described. The connector, generally referred to using the reference numeral2, which serves to connect a fibre optic cable4to a receptacle (not shown) is disclosed. As illustrated, connector2forms part of a cable assembly with an LC type connector plug attached at one end. It should be noted that although the illustrative embodiment of the present invention is described in reference to LC type connectors, it is not intended to limit the invention to this type of connector. Accordingly, the present invention may also be used, for example, with LC, SC, FC, MU and other similar connectors having a ferrule guide and/or support.

Still referring toFIG. 1, the connector is comprised of a connector plug housing6, fabricated from a suitable non-conductive material such as glass filled thermoplastic, through which the optic fibre8extends protruding from a forward end10thereof. The optic fibre8is held rigidly within a hollow ferrule12, fabricated from a suitable stiff non-conductive material such as ceramics, which is in turn held in axial alignment within the plug housing6, thus ensuring that the optical fibre is maintained in substantially axial alignment with the central axis A of the plug housing6. Typically, ferrule12is held rigidly inside the plug housing6, but may also be spring loaded allowing some movement of the ferrule12, and thus the optic fibre8, forward and backwards along the central axis A.

A cavity14, also in axial alignment with the central axis A, is moulded or machined into the forward end10of the plug housing6with the optic fibre8/ferrule assembly12being axially aligned therein. A flexible locking tab or latch16is attached to the outside of the plug housing6allowing the plug housing6to be removeably attached to a suitable receptacle (not shown). The join between optic fibre cable4and the plug housing6is protected by means of a flexible strain-relieving boot18, typically manufactured from rubber, rubberised plastic or the like. A pair of raised tabs as in20may be moulded to the outside of the plug housing which, as will be seen below, mate with corresponding indentations in the receptacle (both not shown).

During fabrication, the optic fibre8is typically inserted through the ferrule12and bonded thereto with an appropriate adhesive or bonding technique. The ends of the optic fibre8/ferrule12are then cut and polished according to a predefined geometry dictated to the standard being implemented. The polishing results in an exposed end22of the optic fibre8extending forward of the forward end10of the plug housing, thereby allowing light to propagate to and from the optic fibre8.

Referring now toFIG. 2, a first illustrative embodiment of a keying system in accordance with the present invention will be described in more detail. The cavity14, through which the optic fibre8/ferrule12assembly extends, is configured to one of a plurality of predefined connector keying geometries. The connector keying geometry is illustratively provided by a cavity having a cavity keying geometry having an oval or egg shaped cross section with a first generally circular concentric portion of radius X1and a keying portion24extending a distance of X2from the centre of the optic fibre8, with X2being illustratively greater than radius X1. As illustrated inFIG. 2, the cavity keying portion24, for example a flute, notch or protuberance, is illustratively symmetric about an axis B, with axis B at a predetermined connector keying angle θ from the horizontal plane C. Of course, the maximum point of extension X2from the core of the optic fibre8must be chosen such that it is sufficiently less than distance y between the centre of the optic fibre8and the outer surface of the plug housing6to ensure that sufficient material remains between the cavity14and the outer surface of the plug housing6for all keying angles θ. The other dimensions of the cavity keying portion24such as the width and profile, are preferably selected such that the cavity keying portion24is difficult to modify, for example by removing the cavity keying portion24using a knife or the like in the case of a protuberance, or to modify without destroying the connector2, thereby deterring the user from modifying the connector2for other purposes.

The cross section of the cavity keying portion24could alternatively be of a different shape, for example a square notch or concave depression in the side wall of the cavity14, or could also be asymmetric. As will be seen below, the combination of the cavity keying portion24with the connector keying angle θ provides one embodiment for the connector portion of the keying system.

Referring now toFIG. 3, a receptacle in accordance with an illustrative embodiment of the present invention will be described. The receptacle, generally referenced using the numeral26, illustratively comprises a receptacle housing28fabricated from a non-conductive material such as glass filled thermoplastic into which are moulded one or more receptacle sockets30. Referring toFIG. 1in addition toFIG. 3, the sockets30are dimensioned for receiving the forward end10of the plug housing6which is held snugly therein. Note that, although in the present illustrative embodiment a receptacle26having a duplex configuration with two (2) sockets30is disclosed, the receptacle26could also be simplex with a single socket30, or provide for three (3) or more sockets30.

Referring back toFIG. 3, the receptacle housing28can be fastened to a patch bay panel or the like (not shown) by means of a pair of integrated flanges32and/or by screws or similar fasteners inserted through the cut outs34in the flanges.

Each receptacle socket30is terminated by a rear wall36and onto which is moulded a raised boss38, illustratively of an oval or egg shape, having a circular ferrule accepting bore40therein. Also moulded into the socket30is a reciprocal locking mechanism42which, referring toFIG. 1in addition toFIG. 3, mates with the latch16, thereby securely interlocking the connector2with the receptacle26when the connector plug housing6is completely inserted into the socket30. A pair of indentations44are also moulded in the socket30which mate with the corresponding tabs20moulded into the connector plug housing6. The tabs20prevent a connector2from being completely inserted into a receptacle26which does not have these indentations. Note that in an alternative embodiment both the tabs20and indentations44could be absent without otherwise affecting the present invention.

Referring now toFIG. 4, each socket30is configured to one of a plurality of predefined receptacle keying geometries. Illustratively, the receptacle keying geometry is provided by a raised boss38having a boss keying geometry, mounted on the rear wall36of the socket30comprising an oval or egg shaped cross section having a first generally circular concentric portion of radius x.sub.1 and a keying portion46, for example a protuberance such as a ridge, projecting a distance of x.sub.2 from the centre of the ferrule cavity40, x.sub.2 being illustratively greater than radius x.sub.1, although in a given implementation the distance of x.sub.2 could also be smaller than x.sub.1. The boss keying portion46is illustratively symmetric about an axis such as D, with axis D at a predetermined receptacle keying angle .phi.sub.1 from the horizontal plane E.

Referring toFIG. 2in addition toFIG. 4, in order for a connector2to correctly mate with a receptacle26, the keying angles θ and φ as well as the lengths X1, X2and x1, x2must match such that the cross section of the raised boss38is the mirror image of the cross section of the cavity14and that the cavity14fits snugly over the raised boss38. For example, in the illustrative embodiment if the keying angles θ and φ do not match, then a portion of the front surface10of the connector plug housing6will butt against the boss keying portion46of the raised boss38thereby preventing the connector2from being correctly inserted into the receptacle26.

It is foreseen that a combination of eight (8) keying angles θ and φ equally distributed around 360° (for example 0°, 45°, 90°, 135°, 180°, 225°, 270°, 315°) will provide adequate keying for most applications, although it will be understood that this could easily be extended to sixteen (16) or even greater with precision manufacturing of the connector2and receptacle26. Referring back toFIG. 4, it is also foreseen that receptacles26can have multiple sockets301,302,303each socket301,302,303having a raised boss381,382,383with differing keying angles φ1, φ2, φ3. It will be understood that although a receptacle26is shown with three raised bosses381,382,383, and three keying angles φ1, φ2, φ3a receptacle26could easily be manufactured having many sockets30, each socket30having a corresponding raised boss38and keying angle φ in any one of a number of combinations. It should also be understood that multiple connectors2with different connector keying angles θ can also be bundled together into a multiple connector assembly (not shown). It should also be understood that sockets such as304may be included with raised bosses such as384which are circular in cross section without the inclusion of a receptacle keying portion, thereby allowing conventional non-keyed connectors to be inserted into the receptacle26.

Note that, although the above illustrative embodiment has been described with the cavity14being moulded or machined into the forward end10of the plug housing6and the raised boss38being located within the receptacle socket30, a person of ordinary skill in the art would understand that, with appropriate modifications, the cavity14could be moulded or otherwise formed into the receptacle socket30and the boss formed in the forward end10of the plug housing6.

Of note is that the present system can be designed for use as a one way system or a two way system. A one way system being defined as a system where keyed connectors can only be connected with a keyed receptacle and a two way system is defined as a system where keyed connectors are backward compatible with legacy system receptacles (or vice versa), allowing for example, keyed connectors to be used with existing receptacles.

Referring toFIG. 4, for example, in an illustrative embodiment of a two way system using existing circular legacy bosses as in384is disclosed. These legacy bosses384allow for the plug housing6of a connector2to be correctly inserted into the socket304regardless of the connector keying angle θ (provided, of course, the length X1ofFIG. 2is less than the length X2and corresponds to the radius of the legacy boss304).

Referring toFIG. 5Ain addition toFIG. 4, an illustrative embodiment of a one way system is disclosed. In order to stop a keyed connector2from being inserted into a socket such as socket304, a tab39could be moulded into or otherwise attached to the outside of the plug housing6. Referring toFIG. 5B, as known in the art, existing LC type behind the wall (BTW) connectors and receptacles include such an assembly. However, the tabs of these prior art connectors extend only partially along the plug housing6and stop at a position Z1well short of the forward end10of the plug housing6. By extending the tab39such that it stops at a position Z2closer to the forward end10of the plug housing6, the plug housing6can also be prevented from being fully inserted into legacy LC receptacles. In order for such a connector2to be correctly inserted into a receptacle26, the socket30will have to be modified to include a notch within which the tab39fits. It will be apparent now to a person of ordinary skill in the art that, in the absence of a receiving groove in the receptacle (all not shown) for the tab39, or a groove of the correct depth, the tab39would butt against the receptacle housing thereby preventing the user from inserting the plug housing6completely into the socket30.

It is also foreseen that the plug housings6and the sockets30be colour coded, with a given colour corresponding to a given pair of keying angles θ, φ, in order to aid the user in determining which connector2belongs in which socket30. Additionally, other coding means such as symbols, alphanumeric characters, etc., may be used alone or in combination with colours to provide a variety of means for distinguishing keyed connectors and receptacle sockets from one another.

Referring now toFIG. 6, a connector2inserted into the first socket30of a duplex receptacle26is shown. Referring toFIG. 7in addition toFIG. 6, and assuming that the keying angles θ, φ are a matched pair, on insertion the forward end10of the plug housing6butts against the rear wall36of the socket30. At this point the latch16is engaged by the reciprocal locking mechanism42thereby holding the plug housing6securely in the socket30. Simultaneously, the ferrule12containing the optic fibre is inserted into the ferrule accepting bore40and the raised boss38is encircled by the cavity14, with the exposed end22of the optic fibre8being substantially in alignment with reference plane F. Insertion of a second connector (not shown) into a similar socket46moulded into the rearward side of the receptacle26and in back-to-back relationship with the socket30would have the effect bringing the exposed end of the second connector's optic fibre into close contact with the exposed end22of the optic fibre8, with the optic fibres being substantially axially aligned, and thereby allowing light propagating in one of the optic fibres to be transferred to the other. Typically (although not necessarily), sockets as in30,46in back-to-back relationship would have the same predefined receptacle keying geometries to ensure that fibre optic cables having compatible connector keying geometries could be interconnected.

The connector2can be readily removed from the receptacle26by depressing the latch16, thereby releasing the reciprocal locking mechanism42.

Referring toFIG. 8, a connector2in accordance with an alternative illustrative embodiment of the present invention is disclosed. In this embodiment the cavity14includes two connector keying portions24,24′ corresponding to two different connector keying angles θ, θ′. In this manner, connectors2can be provided which mate with the sockets having receptacle keying portions with different keying angles φ, provided, of course, that the receptacle keying angle φ matches with one of the connector keying angles θ, θ′. It will now be apparent to a person of ordinary skill in the art that the number of connector keying portions24at a variety of keying angles θ could be increased to provided for a variety of keying situations.

Referring toFIG. 9in addition toFIG. 8, receptacles26having sockets301,302,303with raised bosses381,382,383are disclosed. Raised bosses382,383are depicted as having multiple receptacle keying portions (respectively)462′,462″ and463′,463″,463′″. When combined with a corresponding set of connectors2having multiple connector keying portions24,24′, etc., this allows for a wide variation in the number of potential keys which can be used in a given implementation.

Referring now toFIG. 10, a connector2in accordance with a second alternative embodiment is disclosed including a plug housing6having a cavity48therein, with the cavity48machined or moulded to comprise a generally circular section50and a protuberance52such as a ridge, tab or the like running axially along the inside of the cavity48. Similar to the keying system as discussed hereinabove, the protuberance52is positioned along the inside of the cavity at the requisite keying angle θ. Referring now toFIG. 11in addition toFIG. 10, a receptacle26comprised of one or more sockets30having raised bosses54is shown. The raised bosses54are moulded or machined to include an indentation56, for example such as a notch, slot or flute, therein. Similar to the ridge52, the indentation56is positioned on the raised boss54at a requisite keying angle φ.

It should be understood that although the protuberance52and corresponding indentation56have been portrayed as being symmetrically concave in cross section, other shapes of cross sections, for example a square or triangular notch, could also be applied in the context of the present invention. Additionally, the shapes could be asymmetric.

Referring now toFIG. 12in addition toFIG. 11, in order to prevent a standard connector cable (not shown) from being inserted into a socket30keyed by a raised boss54having an indentation56therein, tabs57can be moulded or otherwise bonded to the inside of the sockets301,302in the receptacle26. In order for a connector to be inserted into a given socket301or302it will be necessary that the connector plug housing (not shown) be modified to include a suitable notch therein for reception of the tab57.

Referring toFIG. 13, a connector2in accordance with a third alternative illustrative embodiment of the present invention is disclosed. In this embodiment the plug housing6is machined or moulded to include a cavity58therein having both an indentation60and a protuberance62therein. The indentation60and a protuberance62are positioned within the cavity58at requisite keying angles as discussed hereinabove. Such a connector2would mate with a receptacle having a socket therein with a raised boss including both an indentation and a protuberance located at keying angles (all not shown) matching the keying angles of the indentation60and the protuberance62of the connector2.

Referring toFIG. 14, a connector2in accordance with a forth alternative illustrative embodiment of the present invention is disclosed. In this embodiment the plug housing6is machined or moulded to include a cavity64having a cross section which varies depending on the depth of the cavity64. Illustratively, the cavity64is comprised of an inner aligning portion66, illustratively cylindrical, and an outer portion68having an illustratively oval or egg shaped cross section with a depth Z and a keying portion70. In line with the keyed connectors as already disclosed hereinabove, the keying portion70is positioned at a predetermined keying angle θ from the horizontal axis C.

Referring toFIG. 15in addition toFIG. 14, the corresponding receptacle26is comprised of one or more sockets30having a raised boss72machined, moulded or other wise formed into a rear wall36thereof. The raised boss72is comprised of a lower portion74having an illustratively oval or egg shaped cross section and an upper aligning portion76, illustratively cylindrical. Additionally, the lower portion74has a protruding keying portion78which is positioned at a predetermined keying angle φ from the horizontal axis E. As will now be apparent to a person of ordinary skill in the art, provided the keying angles θ, φ match, in order for the connector2to be inserted completely into the receptacle socket30, the thickness Z of the lower portion74of the raised boss72must be the same or less than the depth Z of the upper portion66of the cavity64.

Still referring toFIGS. 14 and 15, provided the keying angles θ, φ match and the thickness Z is the same as or less than the depth Z, when the plug housing6is inserted into the socket30of the receptacle26, the cavity64will mate with the raised boss72, thereby allowing the connector2to be securely fastened to the receptacle. If the keying angles θ, φ do not match, then illustratively the forward end10of the plug housing6will butt against the protruding keying portion78of the raised boss72thereby preventing correct insertion of the plug housing6in the socket30. Similarly, if the thickness z is somewhat greater than the depth z then plug housing6will be prevented from being completely inserted into the socket30, thereby preventing the flexible locking tab or latch16from being engaged.

Referring now toFIGS. 16,17and18, a receptacle26in accordance with a fifth alternative embodiment of the present invention will be disclosed. The receptacle26is similar as to described hereinabove with the difference that the receptacle keying portion46of the raised boss includes a bevelled or chamfered outer surface80in order to facilitate insertion of a connector (not shown) into the socket30. Other types of surfaces, for example rounded, could also be implemented in order to facilitate insertion of a connector.

It is also foreseen that the present keying system be field configurable by the installer in order to provide connectors and receptacles with an installer selected keying. Referring toFIG. 19A, for example, the cavity14would be provided in an interchangeable module82for insertion into a suitably adapted receiving cut out84in the forward end10of the plug housing6. The module82would be held in place within the plug housing by clips, an adhesive or other suitable securing means.

Referring toFIG. 19B, alternatively the raised bosses38could be manufactured separately from the receptacle26and including a shaft86having a second geometry, for example a regular geometric form, such as a triangle, square, hexagon, octagon or the like, a series of grooves88therein. The shaft86would be rotated to the requisite receptacle keying angle and inserted in a shaft receiving opening90having a first geometry in the rear wall36of each socket30until the raised boss is in contact with the rear wall36. The shaft receiving opening90could include, for example, a ridged inner surface92adapted to mate with the series of grooves88on the shaft86. The shaft86could also be held in place within the shaft receiving opening90by an adhesive, for example.

Alternatively, the cavities and raised bosses of the invention could be modifiable and adaptable through removal from or addition to the cavities or raised bosses through the provision of a suitable tool (for example by cutting away a portion of a raised boss or fluting the inside of a cavity).

Referring toFIG. 20, although the above invention has been described using BTW receptacles for interconnecting two connectors, the keying system could also be moulded into single sided receptacles94for mounting on active components, attenuators and the like (not shown).

Although the present invention has been described hereinabove by way of an illustrative embodiment thereof, this embodiment can be modified at will without departing from the spirit and nature of the subject invention.