GB2110481A

GB2110481A - Electrical socket with shutter

Info

Publication number: GB2110481A
Application number: GB08232382A
Authority: GB
Inventors: Michael Scott-Coomber
Original assignee: PARK ROYAL PORCELAIN CO Ltd
Current assignee: PARK ROYAL PORCELAIN CO Ltd
Priority date: 1981-11-26
Filing date: 1982-11-12
Publication date: 1983-06-15

Abstract

An electrical socket (1), for a screw fitting plug (10), having a sleeve (11) that (a) carries a shutter (17), (b) is screwed externally to run freely in a corresponding screw in the socket (1) and internally to receive the plug and (c) is resiliently flexible to grip a fully inserted plug (10), whereby a fully inserted plug (10) in electrical connection with contacts (6, 9) in the socket, when rotated for withdrawal, withdraws the sleeve (11) to a position at which an abutment (21) allowing the grip of the sleeve on the plug to be broken is reached and the contacts are isolated by the shutter (17), whereafter full withdrawal of the plug can take place. <IMAGE>

Description

SPECIFICATION Electrical socket The invention relates to screw lampholders and the like.

Attempts have been made in the past to design a screw lampholder, particularly for conventional Edison-screw lamps, in which electrically live parts cannot be left accessible when a lamp is not in place in the holder. None has come into use however. With the increasing emphasis on electrical safety we have returned to the problem, seeking a safety provision that is simple, economically made and certain in action.

We provide an electrical socket, for a screw fitting plug, having a sleeve that (i) carries a shutter, (ii) is screwed externally to run freely in a corresponding screw in the socket and internally to receive the plug and (iii) is resiliently flexible to grip a fully inserted plug, whereby a fully inserted plug in electrical connection with contacts in the socket, when rotated for withdrawal, withdraws the sleeve to a position at which an abutment allowing the grip of the sleeve on the plug to be broken is reached and the contacts are isolated by the shutter, whereafter full withdrawal of the plug can take place.

A particulariy suitable form of sleeve is one of metal on which a single rolled threadform provides the external and internal screw and which is slit axially to provide the necessary flexing. With the usual centre-contact plug a second contact in the socket may readily be engaged by such a sleeve in its inward position, for example to provide full connection to an Edison screw lamp.

Conveniently, electrical access of a centrecontact plug to the corresponding socket contact is indirect, through an electrically conducting stud in the shutter. Conveniently also the shutter, which effectively closes the inner end of the sleeve, is a bar running across it. Conveniently further such a bar projects from slots in the sleeve and engages the abutment referred to above.

An example of a lampholder according to the invention is illustrated in the accompanying drawing in which: Fig. lisa part sectional elevation of the holder with a lamp in place, and Fig. 2 shows a sleeve and shutter separately.

The holder has a body formed of moulded upper and lower parts 1 and 2, for nipple mounting, screwed together at 3 and trapping an insulating terminal plate 4 between them. Fixed to this plate are terminal blocks 5 carrying spring strip contacts, one of which, 6 gives connection with the contact pad 7 of the lamp 8 via a conductive stud 1 8 and the other of which, 9 gives connection with the screw base 10 of the lamp 8 via a sleeve 11.

This sleeve, shown aiso in Fig. 2 is of brass, formed from a tube by rolling the thread 12 and base flange 13 seen in the drawing. It is slit at 14, 1 5 and has slots at 16 (Fig. 2) and opposite (not shown). The slits, made after the rolling, cause the sleeve to take up a slightly oval shape with the long axis through the slits and give a convenient grip on the lamp base. The slots 1 6 receive an insulating shutter 1 7 having a central conductive stud 1 8 through which the contact 6 has electrical access to the contact pad 7.

The movement of the sleeve, starting from the position in Fig. 1 in which the lamp is fully home and in electrical connection with the contacts 6 and 9, is to be carried outwards by anticlockwise turning of the lamp, moving in a screw thread 1 9 in the upper body 1, until shoulders 20 on the shutter contact corresponding abutment shoulders 21 in the upper body. Further rotation of the lamp simultaneously brings the two sets of shoulders into firm engagement and breaks the engagement of the lamp base with the sleeve.

The lamp may then be withdrawn, ieaving the shutter in its safe position. On re-insertion of a lamp the movements are reversed, the lamp base entering until the end of its thread engages the top of the sleeve and it is gripped as the engagement of the shoulders is broken, and the lamp and sleeve then screwing in together until engagement with the contacts 6 and 9 is made.

The lamp may then make a small further part of a turn, bringing it into still firmer engagement with the end of the sleeve, by spreading the split ends of the sleeve very slightly, in readiness for carrying the sleeve outwards when the lamp is next removed.

Claims

1. An electrical socket, for a screw fitting plug, having a sleeve that (i) carries a shutter, (ii) is screwed externally to run freely in a corresponding screw in the socket and internally to receive the plug and (iii) is resiliently flexible to grip a fully inserted plug, whereby a fully inserted plug in electrical connection with contacts in the socket, when rotated for withdrawal, withdraws the sleeve to a position at which an abutment allowing the grip of the sleeve on the plug to be broken is reached and the contacts are isolated by the shutter, whereafter full withdrawal of the plug can take place.

2. A socket according to Claim 1, wherein the sleeve is one of metal on which a single rolled threadform provides the external and internal screw and which is slit axially to provide the necessary flexing.

3. A socket according to Claim 1 or Claim 2, wherein electrical access of a centre-contact plug to the corresponding socket contact is indirect, through an electrically conducting stud in the shutter.

4. A socket according to any previous claim, wherein the shutter, which effectively closes the inner end of the sleeve, is a bar running across it.

5. A socket according to Claim 4, wherein the

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Electrical socket The invention relates to screw lampholders and the like. Attempts have been made in the past to design a screw lampholder, particularly for conventional Edison-screw lamps, in which electrically live parts cannot be left accessible when a lamp is not in place in the holder. None has come into use however. With the increasing emphasis on electrical safety we have returned to the problem, seeking a safety provision that is simple, economically made and certain in action. We provide an electrical socket, for a screw fitting plug, having a sleeve that (i) carries a shutter, (ii) is screwed externally to run freely in a corresponding screw in the socket and internally to receive the plug and (iii) is resiliently flexible to grip a fully inserted plug, whereby a fully inserted plug in electrical connection with contacts in the socket, when rotated for withdrawal, withdraws the sleeve to a position at which an abutment allowing the grip of the sleeve on the plug to be broken is reached and the contacts are isolated by the shutter, whereafter full withdrawal of the plug can take place. A particulariy suitable form of sleeve is one of metal on which a single rolled threadform provides the external and internal screw and which is slit axially to provide the necessary flexing. With the usual centre-contact plug a second contact in the socket may readily be engaged by such a sleeve in its inward position, for example to provide full connection to an Edison screw lamp. Conveniently, electrical access of a centrecontact plug to the corresponding socket contact is indirect, through an electrically conducting stud in the shutter. Conveniently also the shutter, which effectively closes the inner end of the sleeve, is a bar running across it. Conveniently further such a bar projects from slots in the sleeve and engages the abutment referred to above. An example of a lampholder according to the invention is illustrated in the accompanying drawing in which: Fig. lisa part sectional elevation of the holder with a lamp in place, and Fig. 2 shows a sleeve and shutter separately. The holder has a body formed of moulded upper and lower parts 1 and 2, for nipple mounting, screwed together at 3 and trapping an insulating terminal plate 4 between them. Fixed to this plate are terminal blocks 5 carrying spring strip contacts, one of which, 6 gives connection with the contact pad 7 of the lamp 8 via a conductive stud 1 8 and the other of which, 9 gives connection with the screw base 10 of the lamp 8 via a sleeve 11. This sleeve, shown aiso in Fig. 2 is of brass, formed from a tube by rolling the thread 12 and base flange 13 seen in the drawing. It is slit at 14, 1 5 and has slots at 16 (Fig. 2) and opposite (not shown). The slits, made after the rolling, cause the sleeve to take up a slightly oval shape with the long axis through the slits and give a convenient grip on the lamp base. The slots 1 6 receive an insulating shutter 1 7 having a central conductive stud 1 8 through which the contact 6 has electrical access to the contact pad 7. The movement of the sleeve, starting from the position in Fig. 1 in which the lamp is fully home and in electrical connection with the contacts 6 and 9, is to be carried outwards by anticlockwise turning of the lamp, moving in a screw thread 1 9 in the upper body 1, until shoulders 20 on the shutter contact corresponding abutment shoulders 21 in the upper body. Further rotation of the lamp simultaneously brings the two sets of shoulders into firm engagement and breaks the engagement of the lamp base with the sleeve. The lamp may then be withdrawn, ieaving the shutter in its safe position. On re-insertion of a lamp the movements are reversed, the lamp base entering until the end of its thread engages the top of the sleeve and it is gripped as the engagement of the shoulders is broken, and the lamp and sleeve then screwing in together until engagement with the contacts 6 and 9 is made. The lamp may then make a small further part of a turn, bringing it into still firmer engagement with the end of the sleeve, by spreading the split ends of the sleeve very slightly, in readiness for carrying the sleeve outwards when the lamp is next removed. Claims

5. A socket according to Claim 4, wherein the bar projects from slots in the sleeve and engages the abutment.

6. A socket substantially as herein described and shown in the drawings.