GB2338124A

GB2338124A - A plug and socket

Info

Publication number: GB2338124A
Application number: GB9909767A
Authority: GB
Inventors: Gerard Michael John Cardew; Janutz Holland
Original assignee: STATIC SYSTEMS GROUP PLC
Current assignee: STATIC SYSTEMS GROUP PLC
Priority date: 1998-04-29
Filing date: 1999-04-29
Publication date: 1999-12-08
Anticipated expiration: 2019-04-29
Also published as: GB9809092D0; GB9909767D0; GB2338124B

Abstract

A plug has a body 13, a first electrical connector 15, means 14 for receiving an electrical cable 12 and a rim part 23. The rim part 23 has an abutment portion 23a. A socket 11 contains a second electrical connector 18 intended for connection with the first 15. The socket 11 can have a latching means 20 intended to engage with the abutment portion 23a and is aimed to secure the connection of the plug 13 with the socket 11. The plug 13 can be relatively securely connected to the socket 11, but if the cable 12 or plug 13 is pulled or knocked the connection will be broken in preference to damaging the components.

Description

2338124 1 Title: A Plug and a Plug and a Socket

Description of Invention

This invention relates to a plug and a plug and a socket, particularly but not exclusively for use in a hospital environment, for example, a nurse call device, a telephone, other communication device or other device.

Conventionally, in a plug or a plug and socket for a communication device, a cable leading from the device is appropriately connected to the plug, which when engaged with a socket is held in place by a latch mechanism provided on the plug. When undue tension and/or inadvertent tension is applied to the cable, particularly at an angle from the axis of withdrawal of the plug, at least one of the following may occur; the cable can be damaged, the cable may be at least partially detached from the plug, the plug may be damaged and if engaged with a socket, the socket may be damaged.

An object of the invention is to provide a plug and a plug and a socket which overcome or reduce the above problem.

According to a first aspect of the present invention, we provide a plug, the plug having a first receiving portion to receive a first electrical connector, the first electrical connector being engageable with a second electrical connector by movement of the plug in a first direction, the plug further comprising an abutment portion spaced from said receiving portion in a direction transverse to said first direction, and means for engaging a cable.

When a cable is attached to said plug, the first electrical connector is engaged with the second electrical connector and a tension is applied to the cable, the plug is caused to pivot about a fulcrum defined by said abutment 2 portion to disengage the first electrical connector from the second electrical connector.

The first electrical connector, when engaged with the second electrical connector, may be permitted to rotate relative to said first direction through a first angle and when said plug is caused to pivot, the first electrical connector is caused to rotate relative to said first direction by a second, smaller, angle. Said first angle may be in the range 10-30' and particularly may be 200.

Said tension may be in the range 2 to 3 Newtons.

The plug may comprise a plug case, and said abutment portion may be provided by said plug case.

Said means for engaging a cable may comprise latch means to engage a part of the plug.

Said latch means may engage a part of the plug case.

Alternatively, the plug case may be provided with one or more projections and said latch means may engage the or each projection.

The socket may comprise one or more recesses into which said one or more projections is received.

In either alternative, the latch means may comprise one or more resiliently movable hook elements.

The first electrical connector and second electrical connector may comprise telephone connectors of conventional type.

According to a second aspect of the invention we provide a plug and a socket, the plug comprising a plug according to the first aspect of the invention, wherein the socket has a second receiving portion to receive said second electrical connector.

Said abutment portion may contact a pail of said socket to provide said fulcrum.

The socket may comprise latch means to engage a pad of said plug.

3 Where the plug comprises a plug case, said latch means may engage a part of the plug case.

The plug may be provided with said first electrical connector and the socket may be provided with said second electrical connector.

The invention will now be described by way of example only with reference to the accompanying drawings wherein:

Figure 1 is a perspective view of a first embodiment of a plug and a socket according to the second aspect of the present invention, wherein the plug is a plug according to the first aspect of the present invention, Figure 2 is a cross-section on line 2-2 of Figure 1, Figure 3 is a side view of a plug and a socket as shown in Figure I.

Figure 4 is a perspective view of a second embodiment of a plug and a socket according to the second aspect of the present invention, wherein the plug is a plug according to the first aspect of the present invention, Figure 5 is a cross-section on line 5-5 of Figure 4, and Referring now to Figures 1 to 3, a plug is shown generally at 10 and a socket at 11. The plug 10 comprises a plug case 13 and is provided with a first electrical connector 15, which is shown comprising a conventional six way telephone connector of known type, although any other suitable electrical connector may be used as desired. A cable 12, connected to a nurse call device used in hospitals or a telephone or other communication device is attached to the plug case 13 by a clamp means 14 comprising projections moulded integrally with the plug case 13. The cable 12 is connected to the first electrical connector 15. The socket means 11 comprises a mounting element 16 which may be connected to a suitable support means 17, for example part of a metal or plastic connection box of known type. Attached to the mounting element 16 is a second electrical connector 18 attached to a printed circuit board 18a. The second electrical connector 18 is here shown as a conventional 4 six way telephone type connector of known type compatible with the first electrical connector 15. The printed circuit board 18-a is connected to an insulation displacement connector (IDC) 19 of known type. The first electrical connector 15 is engageable with the second electrical connector 18 by movement in a first direction generally shown as axis B. Attached to said mounting element 16 are latch means 20, here comprising a pair of hook elements 21 attached to the mounting element 16 by U- shaped elements 22, the U-shaped elements 22 permitting resilient movement of the hook elements 2 1. The plug case 13 comprises a rim part 23 which is received into a recess 16a of the mounting element 16. The rim part 23 comprises an internally directed part 23a and an abutment portion 23b, the abutment portion 23b being spaced from the first electrical connector 15 in a direction transverse to said first direction.

When the plug 10 is brought into engagement with the socket 11 the first electrical connector 15 is received in the second electrical connector 18 by movement in said first direction. The hook elements 21 engage the inwardly directed parts 23a of the rim 23, and the U-shaped members 22 are sufficiently resilient that the hook means 21 and the inwardly directed part 23a hold the plug 10 in engagement with the socket 11.

The engagement of the hook elements 21 and inwardly directed part 23a are sufficient to hold the socket and plug in engagement under tension caused by normal use.

When a tension is applied to the cable 12, particularly at a large angle A to the axis B as shown in Figure 3, the cable 12 acts on the plug case 13. The plug case 13 is caused to pivot about a fulcrum defined by the region of contact between abutment portion 23b of the rim part 23 and the socket 11. The torque on the plug case causing it to rotate about the fulcrum and hence the force acting to disengage the plug 10 from the socket 11 is proportional to the product of the tension of the cable and the distance from the clamp means 14 to the abutment portion 23b. The tension necessary to disengage the plug 10 from the socket 11 is also dependent on the direction in which the tension is applied to the cable 12. In a typical case said tension may be in the range 2-3 Newtons, although the precise value may vary both within and outside this range depending on at least those factors described above.

When said tension is applied to the cable 12 in a direction not parallel to said first direction, the inwardly directed part 23a on the opposite side of the plug 10 to the abutment portion 23b defining the fulcrum about which the plug 10 is rotated displaces the hook element 21 inwardly against the force of the resilient U-shaped member 22, such that the inwardly directed part 23a disengages from the hook part 21. The plug 10 then disengages from the other hook element 21. The pivotal movement is sufficient to begin to disengage the first electrical connector 15 from the second electrical connector 17, causing the first electrical connector to rotate relative to the first direction through a second angle which is smaller than a first angle, the first angle being the maximum permitted relative rotation between the first electrical connector and said first direction when engaged. If it is attempted to disengage the first electrical connector from the second electrical connector by rotating the first electrical connector relative to the second by an angle greater than the first angle, the first electrical connector will jam in the second electrical connector and damage may occur to either connector. In the present example the first angle is 200 and may be in the range 10 to 30'. The plug 10 is thus disengaged from the latch means 20 and the first and second electrical connectors are sufficiently disengaged such that only a lesser tension is required to completely disengage the first electrical connector 15 from the second electrical connector 18 and completely detach the plug 10 from the socket 11 without damage.

6 It will be clear that the fulcrum about which the plug is caused to pivot may be provided by, for example, contact of the abutment portion 23b with a wall or other surface spaced from said second electrical connector 18 in a direction transverse to said first direction.

If a conventional plug and socket, for example the electrical connectors shown at 15 and 17 without the plug case, were used, the plug would be resistant to being withdrawn at any angle greater than the first angle.

In the present example, the plug may be disengaged from the socket by tension applied to a cable in a direction at an angle at least in the range 120' to a direction perpendicular to the socket and may be disengaged at greater angles.

Of course, where the tension in the cable is applied in the direction of the axis B, the plug is simply disengaged from the socket by virtue of both hook elements 21 being displaced inwardly.

An alternative embodiment of a plug and a socket according to the invention is shown in Figures 4 and 5. Features which are same as those in Figures 1 and 2 are referred to by the same reference numerals.

A plug 10 has a case 29 which is provided with a pair of projections 30, disposed either side of the first electrical connector 15, the plug 10 adapted to be received into a recess 16a provided on a mounting element 16 of a socket 11. The socket 11 has a second electrical connector 18 engageable with said first electrical connector 15. Each projection 30 is received in a corresponding recess 3 1 provided on the socket 11. Also provided on the socket 11 is latch means comprising a pair of hook elements 32 attached to the mounting element 16 by a pair of U-shaped members 33. As in the embodiment of Figures 1 and 2, the U-shaped members 33 permit resilient movement of the hook elements 32. The mounting element 16 is further provided with further recesses 35 to permit the hook elements 32 to be displaced outwardly. The hook elements 32 7 are disposed such that they do not project significantly outwardly into the recess 16a of the mounting element 16. The projections 30 are provided with outwardly facing notches 34 to receive the hook elements 32.

In this example, a clamp means 36 to engage the cable 12 is disposed along the length of the cable 12 inside the plug 10. It would be apparent that such a clamp means 36 can be used in the first embodiment.

The first electrical connector 15 in the present example is not captively mounted on the case 29, but is attached to the cable 12 adjacent a protrusion 37 having a curved surface, in the present example a partspherical surface. The first electrical connector is thus 'floating', that is movable relative to the case 29, such that the first electrical connector 15 does not jam in the second electrical connector 18 if withdrawn at an angle.

As in the embodiment of Figures 1 and 2, the plug 10 is introduced into engagement with the socket 11 to engage the first electrical connector 15 and a second electrical connector 18 by a movement in a first direction. The hook elements 32 are displaced outwardly by the projections 30 as the plug 10 is introduced into the socket 11, and then are urged into engagement with the notches 34 by the resilient U-shaped elements 33 to hold the plug 10 in engagement with the socket 11. When a tension is applied to the cable 12, the plug 10 and socket 11 are disengaged as described hereinbefore in relation to the embodiment of Figures 1 and 2.

It would be apparent that a plug and a plug socket according to the present invention may include features of either or both embodiments as shown in the Figures.

The features disclosed in the forgoing description, or the following claims, or the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for attaining the disclosed result, as appropriate, may, separately, or in any

8 combination of such features, be utilised for realising the invention in diverse forms thereof.

9

Claims

1. A plug, the plug having a receiving portion to receive a first electrical connector, the first electrical connector being engageable with a second electrical connector by movement of the plug in a first direction, the plug comprising an abutrnent portion spaced from said receiving portion in a direction transverse to said first direction, and means for engaging a cable.

2. A plug according to claim 1 wherein the plug comprises a plug case.

3. A plug according to claim 2 wherein said abutment portion is provided by said plug case.

4. A plug according to any one of the preceding claims wherein said means for engaging a cable comprises clamp means.

5. A plug according to claim 4 where dependent on claim 3 or claim 4 wherein said clamp means comprise a part of the plug case.

6. A plug according to any one of the preceding claims wherein the first electrical connector and second electrical connector comprise telephone connectors of conventional type.

7. A plug as herein described with reference to the accompanying drawings.

8. A plug and a socket, the plug comprising a plug according to any one of claims 1 to 7, wherein the socket comprises a second receiving portion to receive said second electrical connector.

9. A plug and a socket according to claim 8 wherein said abutment portion contact a part of said socket.

10. A plug and a socket according to claim 8 or claim 9 wherein the socket comprises latch means to engage a part of said plug.

11. A plug and a socket according to claim 10 where dependent directly or indirectly on claim 2 wherein said latch means engages a part of the plug case.

12. A plug and a socket according to claim 10 where dependent directly or indirectly on claim 2 wherein the plug case is provided with one or more projections and wherein said latch means engages the or each projection.

13. A plug and a socket according to claim 12 wherein the socket comprises one or more recesses into which said one or more projections is received.

14. A plug and a socket according to any one of claims 10 to 13 wherein the latch means comprises one or more resiliently movable hook elements.

15. A plug and a socket according to any one of the preceding claims wherein the plug is provided with said first electrical connector and the socket provided with said second electrical connector.

16. A plug and a socket as described herein with reference to Figures 1, 2 and 3 of the accompanying drawings or Figures 3, 4 and 5 of the accompanying drawings.

17. Any novel feature or novel combination of features described herein and/or in the accompanying drawings.