GB2252683A

GB2252683A - Connection security of coaxial connectors

Info

Publication number: GB2252683A
Application number: GB9202612A
Authority: GB
Inventors: Enis Albert Oates
Original assignee: Individual
Current assignee: Individual
Priority date: 1991-02-08
Filing date: 1992-02-07
Publication date: 1992-08-12
Anticipated expiration: 2012-02-07
Also published as: GB9202612D0; GB2252683B; GB9102720D0

Abstract

A connection between male (3) and female (1) coaxial connectors is fitted with a tubular shroud (10) which prevents unauthorised uncoupling of the connectors. The shroud (10) surrounds the connection so as to prevent direct manual manipulation of the outer sleeve (5) of the male connector (3). The shroud (10) is retained in position by the coupled connectors, for example by means of an inwardly directed annular flange (14) received between the leading end face of the sleeve (5) and a shoulder or other portion of the female connector (1). The rear end face (8) of the sleeve (5) is provided with keying means, such as slots (9), for co-operation with complementary means provided on a key-tool (17) which is inserted into the rear end (11) of the shroud (10) for uncoupling the connectors. If a terminator is used between the connectors the shroud may be extended (24, Fig. 4, not shown) to cover the terminator. A grub screw (25, not shown) in the shroud may secure the shroud to the terminator. <IMAGE>

Description

CONNECTION SECURITY FOR COAXIAL CABLING SYSTEMS The invention relates to the protection of connections between coaxial plug and socket connectors in a coaxial cabling system.

Such systems are commonly used in, for example, offices and banking or broking institutions, forming what are known as local area networks in which computer terminals at a number of different workstations are each connected to a common computer via an outlet socket at the respective workstation. Each terminal is generally connected to its respective outlet socket by means of a coaxial cable (fly-lead) having a male coaxial connector plug at each end, one plugging into a female coaxial connector forming the workstation outlet socket, and the other plugging into a female coaxial connector socket associated with the terminal.If the network is constructed as a "string" system (in which the workstations are connected to the computer in series with each other) instead of as a single system (in which each workstation is connected to the computer individually), each workstation outlet will have two female coaxial connectors for connection to the terminal by two separate coaxial leads fitted with male coaxial connectors at each end.

The male coaxial connector comprises a central pin to which the core of the cable is joined, and a shell to which the cable braid is joined, for example by means of a crimped ferrule, the pin being supported within the shell by a body of insulating material. Correspondingly, the female coaxial connector comprises a central inner socket for receiving the pin of the male connector as a relatively close fit, and an outer socket which is insulated from the inner socket and which is designed to receive the shell portion of the male connector.

Generally, the male connector further comprises an outer sleeve which is retained and rotatably mounted on the shell portion and which is designed to fit over the outer socket of the female connector and to cooperate therewith in order to hold the connectors together and to prevent accidental disconnection.

In a common form of such coaxial connectors, known as BNC connectors, the sleeve of the male connector and the outer socket portion of the female connector together define a coupling of the bayonet type.

Although inadvertent separation of such coupled connectors is prevented satisfactorily, intentional disconnection is very easy. All that is necessary is to release the safety coupling by appropriately turning the sleeve and then to pull the connectors apart. This can lead to loss of data and costly delays if a connection is uncoupled at the wrong time, and also makes it easy to connect an unauthorised terminal into the network in place of an existing terminal in order to gain unauthorised access to the computer and its associated data storage facilities. It is thought that many frauds in banking and broking institutions have been perpetrated "in-house" in this way.

It is an aim of the invention, therefore, to make it almost impossible to uncouple male and female coaxial connectors of the kind described above, and to this end, according to the invention a connection between such connectors is provided with a protector comprising a shroud which substantially surrounds the male connector so as to prevent direct manual manipulation of the outer sleeve thereof and which is retained substantially axially in position by the coupled connectors, the shroud providing sufficient clearance between it and the cable at the rear of the male connector to permit insertion of a suitable key-tool into the shroud for engagement with the sleeve in order to rotate the sleeve relative to the female connector and thereby uncouple the sleeve from the female connector to allow the male connector to be withdrawn therefrom.

As will be appreciated, a coaxial connection formed in accordance with the invention cannot be uncoupled without the aid of a special tool, thus making inadvertent or unauthorised uncoupling of the connection almost impossible. Similarly, the tool will also be needed in order to connect the male and female connectors together with the protector in position.

Preferably the outer sleeve of the male connector is provided with keying means, such as at least two circumferentially spaced slots or holes, in or on the rear end face of the sleeve, the keying means being designed to receive complementary means provided on the key-tool in order that the tool can be engaged positively with the sleeve for the purpose of rotating the sleeve relative to the female connector.

It will of course be appreciated that a male coaxial connector in which the outer sleeve is provided with such keying means, preferably in or on its rear end face, forms a further important aspect of the present invention.

The keying means may be made unique to each workstation or, more likely, to each different network or institution employing the network. For example, when the keying means are constituted by slots or holes provided in the rear end face of the sleeve, the required uniqueness may be provided by suitably varying the spacing and/or number of the slots or holes. Obviously, each different key array used will require its own specific key-tool.

The shape of the protector shroud and the way in which it is retained in position by the coupled connectors may vary depending on the nature of the connection and any terminator or adaptor which it may incorporate.

Generally, the most common connection will be a direct connection between a male connector (e.g. on a fly-lead) and a female connector at a workstation outlet. Such connections will exist in both single and string systems. In this case the protector shroud preferably comprises an open-ended tubular member in which the size of the opening at its rear end is sufficient to permit the passage of the male connector into and out of the shroud, and the forward end of the member has inwardly directed retaining means, such as an annular flange, which prevents the passage of the male connector beyond the forward end but allows the outer socket portion of the female connector to pass through the opening at the forward end.

Preferably the tubular shroud is of stepped construction, the cross-sectional size of the rear end portion being smaller than that of the forward end portion, excluding of course the retaining means at the forward end.

Preferably the tubular shroud will have a circular crosssection.

In the case of a connection to a computer terminal at a workstation, the connection will often be made through a terminator device. This device has a male coaxial connector at one end for coupling to the female connector of the terminal, and a female coaxial connector at its other end for receiving the male connector of the flylead. In this case, the protector shroud may be similar to that just described for the connection between the other end of the fly-lead and the workstation outlet socket in so far as it will be fitted in the same way to the connection between the fly-lead and the female connector socket of the terminator, and in addition the shroud is preferably provided with a tubular extension portion at its forward end which surrounds the terminator along substantially its entire length in order to prevent access to the connection between the terminator and the terminal socket to disconnect the terminator.

Two preferred embodiments of the invention will now be described, by way of example, with reference to the accompanying diagrammatic drawings, in which: Figure 1 is an exploded perspective view of a first embodiment of a connection in accordance with the invention; Figure 2 is a view of the assembled connection, the protector shroud being shown in longitudinal section to show the relative positions of the connected male and female connectors therewithin; Figure 3 is a perspective view of a key-tool for use in making and breaking the connection shown in Figures 1 and 2; and, Figure 4 is a side elevation of a protector shroud for a connection in accordance with the invention incorporating a terminator device.

Figures 1 and 2 illustrate a connection in accordance with the invention between a female BNC coaxial connector socket 1 mounted in a face plate 2 at a workstation, and a male BNC coaxial connector plug 3 fitted to the end of a coaxial fly-lead 4. The construction of each of the BNC coaxial connector socket 1 and connector plug 3 is entirely conventional except for a slight modification to the outer rotatable sleeve 5 of the plug 3. As is conventional, the sleeve 5 is provided with a pair of diametrically opposite slots 6 designed to receive and cooperate with a pair of diametrically opposite pins 7 on the outside of the socket 1 to form a bayonet coupling for holding the connectors firmly together, but in addition the rear end face 8 of the sleeve 5 is provided with a pair of diametrically opposed radial slots 9.As mentioned earlier, the number and position of the slots 9 in the rear end face 8 of the sleeve may be varied as desired.

The connection also includes a protector shroud 10 in the form of a tubular member of circular cross-section having a narrower portion 11 of substantially uniform diameter at its rear end and a wider portion 12, also of substantially uniform diameter, at its forward end, the two portions being interconnected through a step portion 13. At its extreme forward end the tubular shroud member 10 has a radially inwardly directed annular flange 14 defining an opening 15 having a diameter which is greater than the outer diameter of the socket 1 and pins 7, but less than the outer diameter of the leading end of the sleeve 5 of the plug 3.

As can be seen from Figure 2, when the connection is completed, the plug 3 is received in the socket 1 with the sleeve 5 surrounding the socket and the bayonet coupling 6,7 fully engaged to hold the plug and socket together, and the tubular shroud 10 completely surrounds the connected plug and socket with the annular retaining flange 14 at the forward end housed between the leading end of the sleeve 5 and the portion of the socket 1 mounted in the face plate 2. This prevents the shroud 10 from being retracted axially along the cable 4 to uncover the sleeve 5, and the shroud thereby prevents manual disconnection of the plug 3 from the socket 1.

As will be noted, the length of the wider portion 12 of the shroud is slightly longer than the length of the sleeve 5, and the rear end of the narrower rear portion 11 lies rearwardly of the ferrule 16 which crimps the cable 4 to the connector plug 3. The inner diameter of the rear portion 11 is slightly greater than the maximum diameter of the sleeve 5 in order to allow the plug 3 to be passed into and out of the shroud when making or breaking the connection between the plug and the socket.

For the purpose of making and breaking the connection a special key-tool is required and an example of a suitable tool 17 for the connection illustrated in Figures 1 and 2 is shown in Figure 3. This tool comprises a solid cylindrical handle portion 18 at its rear end, and a hollow cylindrical portion 19 at its forward end having an outer diameter which is less than the inner diameter of the rear end portion 11 of the shroud 10, and an inner diameter which is greater than the cable 4 and the ferrule 16 of the plug 3. The hollow cylindrical portion 19 of the tool 17 is provided with a longitudinally extending slot 20 by which a portion of the cable 4 can be laid into the hollow portion 19, the slot 20 opening at the leading end of the tool 17 so that the leading end is formed with a substantially C-shaped end face 21.

This end face 21 is provided with a pair of diametrically opposite axially projecting lugs 22 of a shape and size such that they will fit closely into the slots 9 in the rear end face 8 of the sleeve 5.

To make the connection, the forward end of the tubular shroud 10 is placed over the connector socket 1 until the flange 14 abuts the mounting portion at the root of the socket. The key-tool 17 is then engaged with the connector plug 3 so that the lugs 22 are received in the slots 9 at the rear end face of the sleeve 5, and the cable 4 extends rearwardly within the hollow portion 19 of the tool. While in this condition the plug 3 is then inserted by means of the tool 17 through the rear end portion 11 of the tubular shroud 10 until it engages the end of the socket 1. The tool is then turned slowly until the pins 7 are felt to engage in the slots 6 of the sleeve 5, and the tool is then moved axially to push the plug further into the socket and so that the pins enter the slots 6.The tool 17 is then turned sharply in a clockwise direction for approximately one quarter of a turn to cause the sleeve 5 to rotate relative to the socket 1 so that the pins 7 move into locking engagement with the base of the slots 6 and thereby complete engagement of the bayonet coupling to lock the plug 3 in the socket 1. The tool is then retracted to disengage the lugs 22 from the slots 9 and to remove it from the rear end of the protector shroud 10, which remains held captive in position around the connection. Tugging on the fly-lead 4 will indicate whether or not the connection has been properly made.

If the plug is to be removed from the connector socket 1, the leading end of the key-tool 17 is reinserted into the rear end portion 11 of the protector shroud 10 around the fly-lead 4 and crimping ferrule 16 until it engages the rear end face 8 of the sleeve 5. The tool is then slowly turned until the lugs 22 enter and engage with the key slots 9, whereupon a sharp anti-clockwise twist through one quarter of a turn will unlock the bayonet coupling 6,7 so that the plug 3 can be withdrawn from the protector shroud 10 when the tool is withdrawn.

Figure 4 illustrates an example of a protector shroud which may be used when a coaxial connection incorporates a terminator device between the fly-lead connector plug 3 and a connector socket 1. As shown, the protector shroud 23 is identical to the shroud 10 described above with reference to Figures 1 and 2 (corresponding parts being given the same reference numerals), except that it has a cylindrical extension portion 24 extending forwardly beyond the position of the inwardly directed annular flange 14. The length of this extension portion 24 is such that the shroud 23 will substantially surround the terminator which is connected to the socket 1 so as to prevent disconnection of the terminator from the socket.

The female socket portion of the terminator at the rear end of the terminator projects through the opening 15 defined by the retaining flange 14, and the connector plug 3 of the fly- lead is connected to this socket portion using the key- tool 17 in the same way as described above with reference to Figures 1 and 2. In case difficulty is encountered in effecting this connection as a result of rotation of the terminator, a threaded hole 25 is provided in the side of the extension portion 24 of the shroud 23 to receive a locking grub screw (not shown) which can be screwed into engagement with the body of the terminator to prevent rotation of the terminator and the shroud relative to each other.

Thus, holding the shroud to prevent rotation of the shroud will also prevent rotation of the terminator.

Claims

1. A connection between male and female coaxial connectors wherein the male connector comprises a rotatable outer sleeve which fits over the outer socket of the female connector and cooperates therewith in order to hold the connectors together, the connection being provided with a protector for preventing inadvertent or unauthorised uncoupling of the connectors, the protector comprising a shroud which substantially surrounds the male connector so as to prevent direct manual manipulation of the outer sleeve thereof and which is retained substantially axially in position by the coupled connectors, the shroud providing sufficient clearance between it and the cable at the rear of the male connector to permit insertion of a suitable key-tool into the shroud for engagement with the sleeve in order to rotate the sleeve relative to the female connector and thereby uncouple the sleeve from the female connector to allow the male connector to be withdrawn therefrom.

2. A connection according to claim 1, in which the outer sleeve of the male connector is provided with keying means in or on the rear end face of the sleeve, the keying means being designed to receive complementary means provided on the key-tool in order that the tool can be engaged positively with the sleeve for the purpose of rotating the sleeve relative to the female connector.

3. A connection according to claim 2, in which the keying means comprises at least two circumferentially spaced slots or holes in the rear end face of the sleeve.

4. A connection according to any one of the preceding claims, in which the connectors are of the BNC type wherein the connectors are held together by means of a bayonet coupling defined by the sleeve of the male connector and the outer socket of the female connector.

5. A connection according to any one of the preceding claims, in which the protector shroud comprises an open ended tubular member in which the size of the opening at its rear end is sufficient to permit the passage of the male connector into and out of the shroud, and the forward end of the member has inwardly directed retaining means which prevents the passage of the male connector beyond the forward end but allows the outer socket portion of the female connector to pass into the shroud through the opening at the forward end.

6. A connection according to any one of claims 1 to 4, in which the female connector is at one end of terminator device having a male coaxial connector at its other end coupled to the female coaxial connector socket of a terminal, and the protector shroud comprises an open ended tubular member in which the size of the opening at its rear end is sufficient to permit the passage of the male connector into and out of the shroud, the tubular member having inwardly directed retaining means which prevents the passage of the male connector beyond it while allowing the passage therethrough of the outer socket portion of the female connector of the terminator device, and the tubular member having an extension portion forwardly of the retaining means which surrounds the terminator device along substantially its entire length to prevent access to the connection between the terminator and the terminal socket.

7. A connection according to claim 6, in which the extension portion of the protector shroud is provided with a threaded hole which receives a locking grub screw which can be screwed into engagement with the terminator device to prevent rotation of the terminator device and the shroud relative to each other.

8. A connection according to any one of claims 5 to 7, in which the inwardly directed retaining means of the protector shroud is in the form of an annular flange.

9. A connection according to any one of claims 5 to 8, in which the tubular member is of stepped construction, the cross-sectional size of the rear end portion being smaller than that of the forward end portion, the retaining means being located in the larger portion of the tubular member.

10. A connection according to any one of claims 5 to 9, in which the tubular member has a circular cross-section.

11. A male coaxial connector of the type having a rotatable outer sleeve which fits over the corresponding female connector and cooperates therewith in order to hold the connectors together, the rear end face of the outer sleeve being provided with keying means for engagement by complementary keying means of a key-tool.

12. A connector according to claim 11, in which the keying means comprises at least two circumferentially spaced slots or holes in the rear end face of the sleeve.

13. A key-tool for use in coupling and uncoupling the connectors in a connection according to claim 2, comprising a hollow cylindrical portion at its forward end having an outer diameter which is less than the inner diameter of the rear end portion of the protector shroud of the connection, the hollow cylindrical portion having a longitudinally extending slot by which a portion of the cable attached to the male connector can be laid into the hollow portion, the slot opening at the leading end of the tool so that the leading end is formed with a substantially C-shaped end face, this end face being provided with keying means complementary to the keying means in or on the rear end face of the outer sleeve of the male connector.

14. A connection according to claim 1, substantially as described with reference to Figures 1,2 and 4 of the accompanying drawings.

15. A coaxial connector according to claim 11, substantially as described with reference to Figures 1 and 2 of the accompanying drawings.

16. A protector shroud for a connection according to claim 1, substantially as described with reference to Figures 1 and 2 or Figure 4 of the accompanying drawings.

17. A key-tool according to claim 13, substantially as described with reference to Figure 3 of the accompanying drawings.