GB2280550A - Lampholder - Google Patents

Abstract

A lampholder for a bayonet bulb includes shuttering for obstructing access to bulb engaging contacts when there is no bulb in the lampholder. The lampholder has a body (310) with bayonet slots (311) and bulb engaging contacts (370). The shutter means comprise two apertured members (330, 360). Rotation of an inserted bulb actuates rotation of the first member (330) and means such as gear teeth (335, 352, 365) or cams actuate contrarotation of a second member (360) between a first inoperative position in which the contacts (370) are shielded by at least one of the members, and a second operative position in which the contacts extend through aligned apertures in both members for bearing against a bulb. Use of a contrarotation mechanism allows the lampholder to open larger apertures for the bulb engaging contacts for a selected extent of rotation of an inserted bulb. The lampholder may be adapted to include a transverse switch bar which, after bulb insertion, is operable manually to complete the contrarotation or to bridge the contacts to the lampholder terminals, the switch bar automatically returning to its off position or bulb removal. <IMAGE>

Description

LAMPHOLDER The present invention relates to a shuttered safety lampholder for a bayonet type bulb.

French Patent No. 2403665 discloses a so-called shuttered lampholder in which a shutter is interposed between contacts connected to a power supply and a bulb receiving socket. In use, when a bulb is inserted into the socket, the shutter is rotated by the bulb. This moves apertures in the shutter into alignment with telescopic spring loaded contacts supported by the lampholder. The contacts spring through the apertures in the shutter to engage pad electrodes on the end of the inserted bulb.

However, it has been found that, with the above shutter arrangement, the spring loaded contacts can become embedded in the bulb pad electrodes. This results in the contacts passing through the apertures in the shutter to such an extent that they lock the shutter against rotation. Thus, this prevents bulb removal.

Furthermore, even in the absence of a bulb, it is still possible for a wire, nail or the like to be inserted through the apertures in the shutter by, for example, an inquisitive child. If an inquisitive child should move the shutter to its open position, the spring loaded contacts would spring through the apertures in the shutter, locking the shutter against rotation with no bulb present. Thus, the lampholder may then be left in a highly dangerous condition.

A further problem arises in that, in order to comply with current UK requirements defined in British Standard BS5042, which concerns lampholder construction, a bulb should be rotated in a lampholder by no more than 23".

In addition, the minimum diameter of the bulb engaging contacts should be 3.5mm at 13.2mm centres. The above prior art shutter designs are expected to be unsatisfactory in that they would not comply with British, and possibly, International standards. This is on the grounds that they would require rotation of a bulb far in excess of 23 to provide aperturing in the shutter adequate to allow 3.5mm diameter contacts to extend therethrough.

The present invention seeks to provide an improved shuttered safety lampholder in which the bulb engaging contacts cannot lock the shutter against rotation when no bulb is present in the lampholder and in which the apertures in the shutter are covered when a bulb is not present, and furthermore, the shutter will automatically assume its closed position if a bulb is not present.

Accordingly, with this object in mind, the present invention provides a safety lampholder for a bayonet bulb, the lampholder comprising a body defining slots to receive bayonet pins of an inserted bulb, bulb engaging contacts located within the body for electrical connection to a power source to supply electricity to the bulb and shutter means in the body for selectively obstructing access to the contacts, the shutter means comprising two apertured shutter members capable of relative rotation about a common axis between a first position in which their apertures are obstructed and a second position in which they are aligned and arranged so that rotation of a bulb actuates rotation of a first shutter member and means are provided in the body for actuating contrarotation of a second shutter member between a first inoperative or "closed" position in which the contacts are shielded by at least one of the shutter members and a second operative or "open" position in which the contacts extend through aligned apertures in both shutter members for bearing against a bulb.

Thus, rotation of a first shutter member by, say, 23 may open apertures in the rotatable members having a radial length of 46 . This is adequate to allow passage of a typical contact having a width/breadth of about 3.5mm. Suitably the body of the lampholder comprises a hollow, generally cylindrical housing. Typically the lampholder has "J" type slots, comprising an axial portion and a circumferential portion, along which the bayonet pins of an inserted bulb slide. Conveniently the housing supports resilient flex engaging terminals adapted to be electrically connected to a power supply and to electrically engage the pad electrodes of an inserted bulb. Preferably the lampholder assumes its "open" position only when a bulb is fully inserted.

Suitably the free ends of the bulb engaging contacts are moveable inwardly and outwardly of the housing as the lampholder is closed and opened.

Typically the end of the body or housing opposite the bulb receiving end is closed by a terminal block which supports the resilient flex engaging terminals.

Any such terminal block is preferably fixedly mounted to the housing so as to prevent relative rotation, for example as a snap engaging fit therein.

Preferably the bulb engaging contacts are in the form of hollow cylinders, closed at one end and typically having a flare or rim around the open end which serves to retain them in the lampholder. Typically, compression springs provide a resilient electrical connection between the bulb engaging contacts and the power supply flex terminals. The bulb engaging contacts may have circular, oval or rectangular cross section. Typically the contacts have a width/breadth of about 3.5mm to comply with current industry standards. The free ends of the contacts may be of ramp or angled form. This can be advantageous in assisting displacement of the contacts inwardly of the housing.

In preferred embodiments of the present invention, means are provided for rotationally biasing the first shutter member to the closed position. Example biasing means comprise a torsion spring. Preferably the biasing means act between the first and second rotatable shutter members. Alternatively or in addition, means are provided in the body for ensuring that the shutter members rotate about a common axis. Preferably centralising peg means are associated with the first and second shutter members and the lampholder body. For example, a boss or centralising peg may be defined on one member for accommodation in a central bore or aperture in another member. In addition, the lampholder preferably also has formations for limiting the extent of rotation of the rotatable shutter members.

Preferably, the first and second rotatable shutter members are arranged to be axially movable within the body of the lampholder. In preferred embodiments locking means are provided for inhibiting rotation of at least the first member until it has first been displaced axially inwardly of the body by an inserted bulb. Such locking means may be releasable by axial displacement upon engagement with an inserted bulb. Example locking means may take the form of surface formations in the body.

In particularly preferred embodiments of the present invention, the means for actuating contrarotation of the second shutter member are driven by rotation of the first shutter member by an inserted bulb. Thus, the first member preferably has axial slots to receive the bayonet pins of the bulb. Preferred actuating means comprise a rack and pinion gear mechanism. Example preferred means comprise circumferentially spaced formations on opposing surfaces of said first and second rotatable members and a displaceable member such as a paddle or wheel member located between said first and second shutter members so as to be rotatable about an axis perpendicular to the common axis of rotation of the shutter members, the displaceable member having formations interengageable with formations on said first and second shutter members and arranged such that rotation of a first member by a bulb is effective to drive rotation of the second member in the opposite direction to the first member.

Suitably the displaceable member is in the form of a geared paddle or pinion wheel having formations, such as teeth spaced around its periphery.

Preferably means are provided for inhibiting rotation of the displaceable member about the axis of rotation of the first and second shutter members. This may be effected by locating the displaceable member in an axially extending channel in the lampholder body. Thus, the displaceable member may be free to be moved axially with the rotatable shutter members. In this regard, preferably the displaceable member also has a smooth annular surface for accommodating in such a channel.

In such embodiments, preferably the first and second members are secured against relative axial displacement.

This may be achieved by provision of snap engaging means for interengagment of the first and second shutter members, or by use of a screw, or by any other suitable means.

Typically, the first shutter member, which is engageable by an inserted bulb, is located near the open, bulb receiving end of the lampholder body, and the second shutter member located between the first member and the other, closed end of the body. Alternatively, the first member may be located in the body between the second member and the closed end of the body, and provided with slotted limbs which extend to the body slots through arcuate apertures in the first member.

In other preferred embodiments, the means for actuating contrarotation of the second member include a member movable transversely with respect to the housing, the transversely movable member having formations interengageable with formations on the second member and arranged such that transverse displacement of the transversely moveable member is effective to drive contrarotation of the second member to the operative position.

Preferably, in such embodiments, the second rotatable member also acts as an axially moveable contact carrier for displacing resilient bulb engaging contacts inwardly and outwardly of the lampholder housing between the "closed1, and "open" positions. The contacts may bias the carrier outwardly of the housing. Preferably the contacts and carrier bias the first rotatable member outwardly of the housing. Alternatively, additional biasing means may be provided for the first rotatable member.

Preferably, interengageable surface formations are provided between the first rotatable member and contact carrier to drive axial displacement of the carrier upon rotation of the first member.

In particularly preferred embodiments which include a transversely moveable member, the first rotatable member and transversely moveable member have interengageable formations arranged such that rotation of the first member is effective to drive transverse displacement of the transversely moveable member which, in turn, drives contrarotation of the second rotatable member or contact carrier.

A suitable transversely moveable member (or actuator) is locatable between a terminal block and contact carrier and is slidably mountable in the housing.

The transversely moveable member may comprise a body portion provided with cam following formations opposite ends thereof and a pair of wing formations which extend outwardly from the body portion to locate on support ledges in the lampholder body. Preferably the first rotatable member has cam formations, capable of interengagement with cam followers on the transversely moveable member (or actuator) to drive the latter.

Preferably, means are provided for guiding transverse displacement of the actuator. For example, a guide channel may be provided in a terminal block for the lampholder.

In some preferred embodiments the second rotatable member or contact carrier is rotatable by the transversely moveable member by provision of a formation such as a limit depending from the carrier and arranged to engage with a wing formation on the transversely moveable member.

Suitably, in use, about 1.5mm to 2.0mm of the free ends of the bulb engaging contacts protrude through the contact carrier to engage a bulb. Preferably, the first rotatable member is provided with recesses alongside its apertures to accommodate said free ends of the contacts which the lampholder is in the closed position. Thus, prior to bulb insertion, preferably the free ends of the contacts are seated in the recesses and thereby shielded by the first rotatable member so as to be inaccessible.

Interengageable surface formations are conveniently defined between the contact carrier and first rotatable member to drive axial displacement of the contacts to raise them out of such recesses.

Preferred surface formations comprise humps or ramps arranged on the periphery of the first member and carrier and located near to the walls of the lampholder housing.

Preferably, two sets of hump formations are provided on the inner surface of the first rotatable member, each set of humps comprising four ramp faces, with the two sets of ramps being diametrically opposed and spaced circumferential on the periphery of the shutter. The two ramp faces comprising the first hump in a set, are preferably of equal length and the extent of the hump represents 23 rotation. The two ramp races forming the second hump preferably comprise a first 'off' short ramp face and a second 'on' long ramp face, between them representing 23 of rotation. The second 'on' long ramp face extends approximately 2mm below the level of the bottom of the other ramps.

Preferably, two hump formations are defined on and depend from the outer surface of the contact carrier and extending outwardly of the housing, each hump being arranged to engage a respective set of humps on the first rotatable member to provide that, as the rotatable member and carrier are displaced on bulb insertion (the member being rotated 23 anti-clockwise and simultaneously the carrier being rotated 23 in a clockwise direction or in the opposite direction to that of the shutter) the humps on the carrier ride over the two sets of humps respectively on the member to locate close to the bottom of the 'on' long ramp faces respectively of the rotatable member humps. Thus, the contact carrier is rotated and axially displaced to move the contacts outwards of the housing such that they extend through the aligned apertures in the rotatable member to engage their respective pad electrodes of the inserted bulb.

In other embodiments which employ a transversely moveable member or actuator it may be preferable to arrange the actuator so that it is manually operable independently of the first rotatable member. Thus, the actuator may be provided with limbs which extend laterally beyond the housing, suitably through slots in the housing wall to provide a manually operable switchbar for making and breaking to electrical connection to an inserted bulb. Thus, such embodiments are of manually switchable type.

Preferably such an actuator does not have surface formations for interengagement with the first rotatable member as described in relation to previous embodiments.

Also, preferably the first rotatable member has formations arranged for inhibiting transverse displacement of the actuator when the lampholder is in the inoperative position. However, the first rotatable member and contact carrier are preferably provided with ramp formations for actuating axial displacement of the carrier and contacts. Preferably locking means are provided to prevent transverse displacement of the actuator until the first rotatable member has been rotated by a bulb.

This may be achieved by arranging the transversely moveable member so that it may effect axial displacement of the contacts between positions in which they may bear against the pad electrodes of an inserted bulb and position in which they are displaced inwardly of the housing.

In such manually switchable lampholders should the carrier and actuator be in an operative position when a bulb is removed, formations on the first rotatable member and actuator may be arranged to automatically move the actuator (and thereby the carrier) to the inoperative position. Thus, as a bulb is removed axially from the lampholder the first rotatable member may be biassed outwardly from the housing to this inoperative position.

Preferably, in this state, the first rotatable member inhibits transverse displacement of the actuator.

In yet another embodiment which incorporates a transversely moveable member and a rack and pinion gear mechanism arranged such that rotation of a first rotatable member drives contrarotation of contact carrier, preferably power supply terminals and bulb engaging contacts are supported in the housing and a pair of bridging contacts are carried by the transversely moveable member to effect an electrical connection, between the terminals and bulb engaging contacts, the transversely moveable member being displaceable to displace the bridging contacts to make and break the electrical connection to an inserted bulb.

Suitably the bridging contacts comprise bridging springs. Preferably a formation such as a cam formation is provided on such a transversely moveable member and is arranged to engage a corresponding formation such as a cam follower as the contact carrier which is secured against axial movement relative to a first rotatable member. This preferably arranged so that, should a bulb be removed from the lampholder when the bridging contacts effect an electrical connection, this actuates rotation of the first rotatable member and contact carrier which is effective to drive transverse displacement of the transversely moveable member (by interengagement of the cam formation(s) and follower(s)). Thus, such a switched lampholder should always be in an inoperative state when a user inserts a bulb therein.

Embodiments of the present invention will now be described further, by way of example, with reference to the accompanying drawings, in which: Figs. 1 to 3 are cross sectional views of a lampholder according to a first embodiment, showing the positions of the components after various stages of bulb insertion; Figs. 4 to 8 are enlarged perspective views of components of the first embodiment; Fig. 9 is an enlarged part sectional view of the first embodiment; Fig. 10 is an exploded view of a second embodiment; Fig. 11 is a plan view of the second embodiment; Fig. 12 shows a modification to the second embodiment; Figs. 13 to 15 are cross sectional views of the lampholder according to the second embodiment, showing the positions of the components after various stages of bulb insertion; Figs. 16 to 18 are part cross sectional views of the second embodiment; Figs. 18 to 22 are cross sectional views of lampholder according to a third embodiment; Fig. 23 is a cross sectional view of a lampholder according to a fourth embodiment; Figs. 24 and 25 are part cross sectional views of the fourth embodiment; Figs. 26 to 29 are part cross sectional views of a fifth embodiment; Figs. 30 to 32 are part cross sectional views of a sixth embodiment; Fig. 33 is an exploded view of a seventh embodiment; Figs. 34, 39 and 40 are plan views of part of the eight embodiment; Figs 35 to 38 are cross sectional views of the Fig.

33 embodiment; Figs 41 and 42 are part cross sectional views of the Fig. 33 embodiment; Fig. 43 is a cross sectional view of a modification of the Fig. 33 embodiment; Fig. 44 is a plan view of part of the Fig. 43 embodiment; Fig. 45 is a cross sectional view of a ninth embodiment; Fig. 46 is a plan view of part of the ninth embodiment; and Figs 47 and 48 are part cross sectional views of the ninth embodiment.

Referring now to Figs. 1 to 9 there is illustrated a first example of a shuttered lampholder comprising a hollow cylindrical housing 110 into one end of which can be received the cap of a bayonet type bulb. The housing 110 is provided with "J" slots 111 at its open end to receive the respective bayonet pins of a bulb. The housing 110 is also provided with a screw thread 115 to retain a shade locking ring. In use, a cover (not illustrated) would be secured to the top of the lampholder housing 110 so as to cover the terminals 155 whilst providing an entry port for the power supply flex.

The end of the housing opposite the bulb receiving end, generally referred to as the "inner end" is closed by a terminal block 150 which is secured in fixed relation to the housing 110. The terminal block also supports a pair of resilient terminal contacts 154, each comprising a flex engaging terminal 155, a bulb engaging contact 157 and a bridging spring 156. The bulb engaging contacts 157 are of generally cylindrical shape, having flared ends 158 which locate on steps 152 in bores 151 in terminal block. The free ends of the contacts have opposed ramp formations 159. The terminal contacts 154 extend through the terminal block 150 so as to be accessible on opposite sides thereof. A pair of limbs 160 are also defined on and depend from the periphery of the inner surface of the terminal block, 150, and are arranged to engage a shutter, described in more detail below.

A first rotatable member, referred to as a shutter 120 is located in the bulb receiving end of the housing 110. The shutter 120 has an annular skirt 121 which extends to the open end of the housing 110. The skirt 121 is provided with a pair of axial slots 122 which align with the axial portion 112 of the "J" slots 111 in the housing.

A pair of spaced elongate arcuate apertures 123 are diametrically opposed on the shutter 120. A pair of limbs 125, terminating in hook means 126 and located between apertures 123 and extend into the housing 110 from the inner surface of the shutter 120.

A number of upstanding gear type driving teeth 128 are defined at the periphery of the inner surface of the shutter 120 together with vertical rotational stop faces 127. The shutter 120 is arranged so as to be movable axially and rotationally with respect to the housing 110.

A second rotatable member, referred to as cover plate 130 is also located in the housing 110 between the terminal block 150 and shutter 120. The cover plate 130 is of generally disc shape and provided with a pair of spaced, elongate arcuate apertures 131 and a central bore 132. Depending formations 136 extend from the outer surface of the cover plate 130 alongside each aperture 131. The lips are arranged to locate in shutter apertures 123. The central bore 132 is arranged to receive the hooked limbs 125 of the shutter 120. In this way the cover plate 130 is secured to the shutter 120 against relative axial movement. This also provides a sub-assembly to assist in manufacture of the lampholder.

A number of gear teeth 135 are also defined at the periphery of the cover plate, and on the surface which, in use, is facing the shutter 120. A pair of vertical stop faces 134 are also provided at the periphery of the cover plate and arranged to be engaged by the limbs 160 which depend from the terminal block 150.

A geared wheel member 200, having a plain or smooth peripheral portion 201 and a number of gear teeth 202 recessed into its periphery, locates in the housing 110 between the shutter 120 and cover plate 130. The teeth 202 of wheel member 200 are arranged to engage the teeth 135 in the cover plate 130 and the teeth 128 in the shutter 120. This is best illustrated in Fig. 4, which shows the shutter, cover plate and gear wheel subassembly prior to insertion into the housing 110.

When the above sub-assembly is located in the housing 110 the limbs 160 depending from the terminal block 150 engage the geared wheel 200 by the plain band 201. This prevents the wheel from rotating relative to the axis of the housing 110 but allows the wheel 200 to turn and move axially with respect to the housing 110 as the shutter, cover plate and geared wheel sub-assembly are moved axially with respect to the housing 110. Fig.

5 shows how, when the shutter 120 is rotated 23 degrees in one direction it causes the geared wheel 200 to rotate the cover plate 130 23 degrees in the opposite direction to the shutter 120.

Prior to bulb insertion, (ref Figs. 1 and 9A) the bulb engaging contacts 157 are supported in the terminal block 150 by their flared ends 158, which locate on the steps 152 in the bores 151. The contacts 157 are loaded against the steps 152 by bridging springs 156. The free ends of the contacts 157 locate within the apertures 131 in the cover plate 130. The extreme ends 159A of the contacts 157 are positioned just clear of the inner surface of the shutter 120 and partially over the shutter apertures 123. The apertures 123 are closed by the cover plate 130 including formations 136. At this stage the slots 122 in the shutter 120 are aligned with the axial portions 112 of the "J" slots 111. The flex engaging terminals 155 are retained in the terminal block 150 by snap-engagement and the bridging springs 156 provide a resilient electrical connection between the terminals 155 and contacts 157.

Figs. 2 and 9B illustrate the position of the components after axial insertion of a bulb into the housing 110. Here, the contacts 157 have been depressed inwardly of the housing 110 (against the force of the springs 156) by the shutter 120 and cover plate 130 as the shutter, cover plate and geared wheel are moved inwards of the housing 110 by the end of the bayonet cap of the bulb. The flared ends 158 of the contacts 157 are raised off the steps 152 further loading the springs 156.

As the bulb is rotated in the lampholder it rotates the shutter 120 with it. Thus, as the bayonet pins of the bulb are engaged in the slots 122, the shutter 120 is rotated from its closed to its open position. This simultaneously turns the geared wheel 200 which causes the cover plate 130 to rotate in the opposite direction to the shutter 120 from its closed to its open position.

The contacts 157, via their angled faces 159, slide through the apertures between the shutter 120 and cover plate 130 to bear against their respective pad electrodes 180 of the inserted bulb.

When a bulb is removed from the lampholder the foregoing procedure is reversed and the lampholder components reassume the position illustrated in Figs. 1 and 9A, in which position the live terminal contacts 154 are inaccessible and not visible behind the shutter 120 and cover plate 130.

In use, when the lampholder of Figs. 1 to 9 is assembled, and with no bulb present, the lampholder components assume the position illustrated in Figs. 1 and 9A. The axial shutter slots 122 are aligned with the axial portion 112 of the "J" slots 111. The contacts 157 are located behind the shutter 120 and cover plate 130.

The shutter, cover plate and geared wheel assembly may be biased outwards of the housing 110 and rotationally to the first shuttered position by spring means, such as a torsion spring (not illustrated). The shutter 120 and cover plate 130 are in their respective closed positions in which apertures 123 in the shutter 120 are non-aligned with the respective apertures 131 in the cover plate 130.

The shutter assembly is supported in the housing 110 on the ledge 117.

Insertion of a bulb is done in two stages, an axial stage and a rotational stage. As a bulb is inserted axially into the lampholder, the bayonet pins engage in the aligned slots 112 and 122 and the pad electrodes 180 on the end of the bulb engage the outer surface of the shutter 120 and move the shutter, cover plate and geared wheel assembly inwards of the housing 110. This depresses the contacts 157 via their free ends 159A until the bayonet pins reach the end of the axial portion 112 of the "J" slots 111. The lampholder components thus assume the position illustrated in Figs. 2 and 9B after this axial stage of bulb insertion.

Rotation of the bulb in the lampholder causes the shutter 120 to rotate with it from its closed to its open position. At this stage the shutter teeth 128 interengage with teeth 202 on the wheel member 200 to turn the wheel 200. The wheel 200 also actuates rotation of the cover plate 130, via interengagement of teeth 202 and 135, in the opposite direction to the shutter 120.

This action moves the two pairs of apertures 123 and 131 in the shutter 120 and cover plate 130 respectively into alignment. As the shutter and cover plate assume their open positiOns, the loaded contacts 157 pass through the now open aligned apertures between the shutter 120 and cover plate 130 to engage their respective pad electrodes 180 of the inserted bulb. The lampholder components thus assume the position illustrated in Figs. 3 and 9C when a bulb is fully inserted.

As the shutter 120 and cover plate 130 are rotated on removal of a bulb, from their open back to their closed position, they engage the angled faces of 159 of the contacts 157. This facilitates moving the contacts 157 inwards of the housing 110 and back behind the shutter 120 and cover plate 130. As the bulb is removed axially from the lampholder the loaded contacts 157 move the shutter, cover plate and gear wheel sub-assembly outwardly of the housing 110 and against the support ledge 117. At this stage the sub-assembly is locked against rotation until it is moved axially inwardly of the housing. The flared ends 158 of the contacts 157 locate on the terminal block steps 152 and the lampholder components assume the position illustrated in Figs. 1 and 9A.

Returning to Figs. 4 and 5, stop faces 127 and 134 on the shutter 120 and cover plate 130 respectively engage limbs 160 depending from the terminal block 150.

The limbs 160 effectively act as rotation stops to limit the extent of rotation of the cover plates 130 and shutter 120. Formations 136 on the cover plate 130 may also provide stop means. The cover plate 130 and shutter 120 are typically arranged to allow 23 rotation of the shutter 120 and 23 rotation of the cover plate 130 in opposite directions. This gives a total of 46" which is sufficient to provide a pair of apertures through which a 3.5mm diameter bulb engaging contact may extend through in accordance with current UK requirements set by British Standard BS 5042.

It will be appreciated that more than one geared wheel member 200 may be used according to this invention.

For example it may be advantageous to use two diametrically opposed wheels.

The lampholder as illustrated in Figs. 1 to 3 suitably has a metal shell housing 110. It should be understood, however, that the principles of the present invention may be incorporated into a lampholder having a plastic housing 110. In such a lampholder, the plain band of the geared wheel member could be arranged to engage in a vertical slot defined internally in the housing wall. An additional rotatable component would be provided supporting limbs which extend to the housing "J" slots. The limbs would be provided with cut-outs to engage the bayonet pins of a bulb. The rotatable component would typically drive a modified shutter which would turn the geared wheel to rotate a cover plate. All other aspects would be similar to those of Figs. 1 to 9.

Referring now to Figs. 10 to 18, there is illustrated a shuttered lampholder according to a further embodiment of the present invention. The lampholder comprises a hollow cylindrical housing 10 having the usual "J" slots 11 (i.e. comprising an axial portion 12 and a circumferential portion 13). The housing 10 has a screw thread 16 to retain a shade locking ring, and cutouts 15 are provided to engage a cover for flex terminals whilst providing an entry port for the power supply flex.

Annular support ledges 20 and 20A are provided internally in the housing 10 to support a first rotatable member comprising shutter 30. Vertical stop faces 21 defined in the housing wall engage stops 45 on the shutter 30. This prevents rotation of the shutter 30 relative to the housing 10 until the shutter 30 has first been moved inwardly of the housing 10 by axial insertion of a bulb.

The end of the housing 10 opposite the bulb receiving end is closed by a terminal block 70 having flex engaging terminals 74.

The shutter 30 is mounted in the open end of the housing 10 and comprises a plate or base portion 31 defining a pair of limbs 32 which, in use, extend outwardly to the open end of housing 10 to "J" slots.

The limbs 32 locate on the support ledges 20, and are provided with axial slots 33 for engagement with the bayonet pins of an inserted bulb. A pair of stop lugs 45 are defined at the periphery of the shutter 30 to engage vertical stop faces 21 in the inside of the housing.

This is arranged so that the shutter 30 has to be moved inwardly of the housing 10 to an unlocked position in which it clears stop faces 21 before it can be rotated relative to the housing 10.

The housing "J" slots 11 and shutter slots 33 are arranged such that rotation of a bulb causes the shutter 30 to rotate with it. A central bore or aperture 40 and a pair of elongate diametrically opposed arcuate apertures 37 are defined in the surface of the shutter 30. A small indent or recess 38 is provided adjacent each aperture 37. This is shown more clearly in Figs. 16 to 18.

A further pair of limbs 34 extend inwardly of the housing from the shutter 30. Lugs 35 defined on the ends of the limbs 34 provide cam surfaces 36 and 36A. At least two sets of hump formations are also provided at or close to the periphery of the shutter 30. Each set of hump formations comprises a first hump 41 and a second smaller hump 42. The large hump 41 comprises two opposed generally equivalent ramp faces 41A and 41B. Preferably each ramp is at an angle of 45". The small hump 42 comprises a short "off" face 42A and a long "on" face 42B which typically extends approximately 2mm below the level of the bottom of the other ramp faces.

A second rotatable member referred to as a contact carrier 50 locates in the housing 10 on the shutter 30 and is rotatable and movable axially inwards and outwards with respect to the housing 10. The carrier 50 is provided with a pair of spaced contact receiving apertures 51. A sleeve formation 52 depends from the outer surface of the carrier 50 to form a skirt around the apertures 51. Centralising pegs 53A and 53B are defined on and extend centrally from the internal and external surfaces respectively of the carrier 50. The peg 53A locates in a central bore 77 in the terminal block 70 and the peg 53B locates in a central bore 40 in the shutter 30. This is to ensure that the carrier 50 and shutter 30 rotate around a common axis.

At least two hump formations 55 are defined on and extend axially from the periphery of the outer surface of the carrier 50. In use the humps 56 engage a set of humps 41 and 42 on the shutter 30. A limb 54 also extends from the inner surface at the periphery of the carrier 50 and its use will be explained below.

Bulb engaging contacts 57 are supported by the carrier 50 within the spaced apertures 51. The contacts 57 are supported within the apertures 51 by their flared ends 58. One end of a bridging spring 59 locates within the hollow contacts 57, the other end locating within a blind bore in the flex terminal 74 in the terminal block 70. The springs 59 provide a suitable, resilient, electrical bridging connection between contacts 57 and flex terminals 74 and accommodate relative movement, rotationally and axially of the contacts 57 with respect to the flex terminals 74. Preferably the closed ends 57A of the contacts 57 protrude about 1.5mm to 2.0mm past the end of the sleeve formations 52 on the carrier 50. The closed or free ends 57A of the contacts 57 locate in indents or recesses 38 in shutter 30, prior to bulb insertion.

A transversely movable actuator member 60 is also located in the housing 10, preferably in the gap defined between the carrier 50 and terminal block 70. It is supported on ledges 19 defined in the housing wall. The actuator 60 is slidably mounted for movement transversely within the housing 10 between a first inoperative position and a second operative position. The actuator 60 comprises a body portion 61, provided with a pair of cam following formations 67A and 67B, (one at each end thereof) which, in use, engage respective cams 36 and 36A on the shutter 30. This provides that rotational movement imparted to the shutter 30 on bulb insertion is converted to transverse movement of the actuator 60.

The actuator 60 also has a pair of wing portions 62A and 62B which extend outwardly from the body 61 to locate on the housing support ledges 19. An elongate aperture 64 is provided centrally in the body 61, through which peg 53A of the carrier 50 extends to locate in a bore 77 in the terminal block 70. A cutout 63 is provided in wing 62A to accept the upstanding limb 54 depending from the inner surface of the carrier 50. This limb 54 provides that transverse movement imparted to the actuator 60 by the shutter 30 is converted to rotational movement of the carrier 50 in the opposite direction to that of the shutter 30. Thus, a contramotion mechanism is provided.

The shutter 30 is movable between a closed position in which the apertures 37 and contacts 57 are non-aligned and an open position in which the apertures 37 are aligned with the bulb engaging contacts 57. Rotation of a bulb in the housing 10, on insertion causes the shutter 30 to rotate with it from its "closed" to its "open" position and removal of a bulb causes the shutter to rotate back from its "open" to its "closed" position.

The contacts 57, via the springs 59, act to bias the carrier 50 outwardly of the housing 10 and against the shutter 30. This biases the shutter 30 into its first locked position and against the support ledges 20 and 20A.

Preferably, two spaced hump formations 55 depend from the periphery of the outer surface of the carrier 50 to interengage respectively two sets of double hump formations defined on the periphery of the inner surface of the shutter 30. The double sets of hump formations on the shutter 30 comprise a first hump 41 having a first ramp face 41A and a second ramp face 41B and a second hump 42 comprising a short "off" ramp face 42A and a long "on" ramp face 42B which extends outwards of the housing to a level approximately 2.Omm below the level of the bottom of the other ramp faces. The interengagement of the ramps 41,42 and 55 provide that, as the shutter 30 is rotated by the bulb on insertion from its closed to its open position, the actuator 60 is moved transversely within the housing from its first to its second position.

Thus in turn causes the carrier to rotate from its first to its second position.

The hump formations 41, 42 and 55 also cause the carrier to be displaced axially inwards of the housing 10 as it is rotated. Thus the carrier 50 is moved axially inwards of the housing 10 as the humps 55 rise up the first ramp faces 41A of the humps 41, and outwards of the housing 10 as humps 55 move down the second ramp face 41B. The carrier 50 is again moved inwards of the housing 10 as the humps 55 rise up the short "off" ramp face 42A of the humps 42 and outwards of the housing 10 as the humps 55 move down the long "on" ramp face 42B.

This allows the carrier 50 to be moved approximately 2.Omm further outwards of the housing 10 with respect to the shutter 30. This is best illustrated in Figs. 16 to 18. Thus the ends 57A of the contacts 57 extend through the aligned apertures 37 in the shutter 30 to engage their respective pad electrodes 180 of the inserted bulb.

The reason for providing double humps will become evident later, when it is explained that the shutter is a common component in a double purpose lampholder. It should be appreciated that, as the humps 55 ride over the humps 41 and 42, the shutter 30 and carrier 50 are simultaneously being rotated in opposite directions to each other.

In use, with the lampholder of Figs. 10, 11 and 13 to 18 assembled and with no bulb present the lampholder components assume the positions illustrated in Figs. 13, 14 and 16. Shutter slots 33 are aligned with the axial portion 12 of the housing "J" slots 11. The contacts 57 are located behind the inner surface of the shutter 30, their ends 57A located in the recesses 38 and thereby inaccessible and not visible. The carrier 50 is biased outwards of the housing 10 by the loaded contacts 57.

The humps 55 on the carrier 50 are urging the shutter 30 outwards of the housing 10 and against the support ledges 20 and 20A. The shutter 30 is in its closed position and locked against rotation relative to the housing.

Insertion of a bulb is done in two stages, an axial stage and a rotational state. As a bulb is inserted axially into the lampholder, the bayonet pins engage the aligned slots 12 and 33 and the pad electrodes 180 of the bulb abut against the outer surface of the shutter 30.

This moves the shutter 30 and thereby the carrier 50 inwards of the housing 10 against the force of the loaded contacts 57. This action unlocks the shutter 30 to permit it to be rotated within the housing 10.

As the shutter 30 is rotated by the bulb, the cam 36 on the shutter 30 engages the cam follower 67A causing the actuator 60 to be moved transversely of the housing 10 from its first, inoperative, position to its second, operative, position. Simultaneously, the humps 55 ride over the humps 41 and 42 as the carrier 50 is rotated in the opposite direction to the shutter 30 by limb 54 on the actuator 60. This action moves the carrier 50 rotationally and displaces it axially relative to the shutter 30 and housing 10 to raise the ends 57A of the contacts 57 out of the recesses 38.

As the humps 55 on the carrier 50 move down the long "on" ramp 42B the loaded contacts 57 move the carrier 50 outwards of the housing 10 such that the ends 57A of contacts 57 extend through the now aligned apertures 37 in the shutter 30 to engage their respective pad electrodes 180 of the inserted bulb. The lampholder components thus assume the "on" position best illustrated in Figs. 15 and 18. The ramp faces 42B allow the surfaces of the carrier 50 and shutter 30 to move together and thereby the carrier 50 to move further outwards of the housing 10. This allows the ends of the contacts 57 to project, if required, substantially beyond the outer surface of the shutter 30.

As the shutter 30 is rotated by the bulb on bulb removal, the cam 36A engages the cam follower 67B to move the actuator 60 transversely of the housing from its second back to its first position. Via the limb 54 this rotates the carrier 50 in the opposite direction to the shutter 30. The carrier 50 is simultaneously displaced axially inwards and outwards of the housing 10 as humps 55 ride over respective humps 41 and 42 on the shutter 30. This moves the contacts 57 back through the apertures 37 to be relocated in the recesses 38 prior to the shutter 30 assuming its closed position (ref Fig.

16). Thus, the interengagement of humps 55 and ramp faces 42B provide a means of raising the contacts 57 back through the apertures 37 in the shutter 30.

As the bulb is removed axially from the lampholder the loaded contacts 57 move the carrier 50, and thereby the shutter 30, outwardly of the housing 10. The limbs 32 of the shutter are moved against the support ledges 20 and the lampholder components assume their first position, best illustrated in Figs. 13, 14 and 16. In this position the shutter is locked against rotation relative to the housing 10.

Referring now to Figs. 12 and 19 to 22, there is illustrated a slightly modified version of the embodiment of Figs. 10 , 11 and 13 to 18 in which an alternative actuator 60A is provided. This actuator 60A defines limbs or longer end portions 66A and 66B and on which the cam follower 67A has been omitted. The limbs 66A and 66B extend externally of the housing 10 through slots 22 in the housing wall, thus converting the lampholder of Fig. 10 into a manually switchable type. The housing 10, shutter 30, carrier 50, terminal block 70, terminals 74, contacts 57 and bridging springs 59 are all common components. A cover (not illustrated) would be provided with cutouts to accommodate the limbs 66A and 66B.

In use, with the lampholder of Figs. 19 to 22 assembled, and with no bulb present, the components assume the position illustrated in Figs. 16, 19 and 20.

As a bulb is inserted axially into the lampholder, the pad electrodes 180 of the bulb engage the outer surface of the shutter 30. This moves the shutter 30 and thereby the carrier 50 inwards of the housing 10 against the force of the loaded contacts 57, unlocking the shutter 30 to be rotated with respect to the housing 10. The actuator 60A cannot yet be moved by depressing the limb 66A as the cam follower 67B will abut against the inner surface of the limb 34 of the shutter 30. Thus, it is necessary to rotate the shutter 30 before the actuator 60A can be moved transversely relative to the housing 10.

As the shutter 30 is rotated by the bulb on insertion, rather than with the previous embodiment, the cam 36 does not engage the actuator 60A. This is because the "on" cam follower 67A has been omitted. As the shutter 30 is rotated from its closed to its open position humps 41 are forced past the humps 55 on the carrier 50. This causes the carrier 50 to be displaced axially inwards and then outwards of the housing 10.

This action raises the ends 57A of the contacts 57 out of the recesses 38, and the humps 55 locate in the intermediate position between humps 41 and 42 on the shutter 30 (best illustrated in Figs. 17 and 21). As the shutter is now in its open position it does not obstruct the actuator 60A. The cam 36A is now positioned to receive the cam follower 67B when the actuator 60A is moved transversely of the housing 10 from its first to its second position.

The lampholder is now in its "switched off" position, in which the ends 57A of the contacts 57 are unshuttered but held in spaced relationship from the pad electrodes 180 of the inserted bulb and back from the outer surface of the shutter 30. The lampholder may now be switched "on" and "off" in conventional manner by manually moving the actuator 60A between its two positions.

Depressing the limb 66A in order to switch the lampholder "on" moves the actuator 60A transversely of the housing 10. This rotates the carrier 50 (in a direction opposite to that of the shutter 30), simultaneously causing the carrier 50 to be displaced axially inwards of the housing 10 (as its humps 55 ride up the short "off" ramps 42A) and outwards of the housing 10 (as the humps 55 move down the long "on" ramps 42B of the humps 42). The loaded contacts 57 move the carrier 50 outwards of the housing 10 such that the ends 57A of said contacts 57 extend through the aligned apertures 37 in the shutter 30 to engage their respective pad electrodes 180 of the inserted bulb. The lampholder components assume the position best illustrated in Figs.

18 and 22 when the lampholder is in its "switched on" position, in which the "off" cam follower 67B has moved into the "off" cam 36A and is thus positioned to be engaged by the cam 36A should the bulb be removed in this "switched on" position rotating the shutter 30.

The actuator 60A may now be moved manually in conventional manner between its two positions in order to switch the lampholder "on" and "off".

Depressing the limbs 66B in order to switch the lampholder "off" moves the actuator 60A transversely of the housing 10 from its second back to its first position. This causes the carrier 50 to be simultaneously rotated and axially displaced relative to the shutter 30 and housing 10, such that the humps 55 move back up the long "on" side 42B of the ramps 42.

This moves the carrier 50 and thereby the contacts 57 inwards of the housing and the ends 57A of the contacts 57 back through the apertures 37 in the shutter 30. The humps 55 locate between the humps 41 and 42 in the intermediate position. This switched "off" position is best illustrated in Figs. 17 and 21, in which the ends 57A of the contacts 57 are held in spaced relationship from the pad electrodes 180 of the bulb. Switching the lampholder between its two positions simply makes and breaks electrical connection between the contacts 57 and electrodes 180 by raising and lowering the carrier 50 and thereby the contacts 57 to engage and disengage the pad electrodes 180. Interengagement of the humps 55 and 41 and 42 also provide indent means to locate the carrier 50 in its intermediate "switched off" position.

Should the actuator 60A be in its second position (i.e. the lampholder "switched on" ref Fig. 18) when the bulb is removed, the "off" cam 36A on the shutter 30 will engage the cam follower 67B and automatically move the actuator 60A from its second back to its first position.

This rotates the carrier 50 in the opposite direction to the shutter 30, the carrier 50 being simultaneously displaced axially inwards and outwards of the housing 10 as the humps 55 ride over the humps 41 and 42 respectively on the shutter 30, and the humps 55 locate adjacent the ramps 41A of the humps 41. The ends 57A of the contacts 57 relocate in the recesses 38 defined in the shutter 30, as shown in Fig. 16.

Should the actuator 60A and carrier 50 be in their first positions (i.e. the lampholder "switched off" ref Figs. 14 and 21) when the bulb is removed, the shutter 30 will be rotated from its open back to its closed position. The humps 41 on the shutter 30 engage the humps 55 on the carrier 50 to displace the carrier 50 axially inwards and outwards of the housing 10, as the humps 55 ride up the faces 41B and down the faces 41A of the humps 41. The shutter then assumes its closed position with the ends 57A of the contacts 57 locating in the recesses 38.

On axial removal of the bulb the shutter assumes its locked position. When removing a bulb in this "switched off" position there will be a tendency for the shutter 30 to move the carrier 50 and thereby the actuator 60A towards the "switched on" position. However, this is prevented by the cam 36A which will ensure the actuator 60A, and thereby the carrier 50, are in their first inoperative positions prior to axial bulb removal and locked in said inoperative positions by the shutter 30 when the bulb is fully removed from the lampholder.

Referring now to Figs. 23 to 25, there is illustrated a further slightly modified version of Fig.

10, in which the humps 41 have been omitted from the shutter 30. All other aspects of this embodiment are identical to that of Figs. 10, 11 and 17 to 18.

In use, with the lampholder of Figs. 23 to 25 assembled and with no bulb present, the components assume the position illustrated in Figs. 23 and 24. As a bulb is inserted axially into the lampholder the pad electrodes 180 of the bulb engage the shutter 30 moving the shutter and thereby the carrier 50 inwards of the housing 10, against the force of the loaded contacts 57.

This unlocks the shutter 30, permitting it to be rotated relative to the housing.

As the shutter 30 is rotated by the bulb, the cam 36 engages the cam follower 67A moving the actuator 60 transversely of the housing 10. This action simultaneously rotates the carrier 50 in the opposite direction to the shutter 30. This causes the carrier 50 to be displaced axially inwardly of the housing 10 (as its humps 55 ride up the face 42A of the short "off" ramp 42) and outwardly of the housing 10 (as the humps 55 move down the long "on" face 42B). The loaded contacts 57 move the carrier 50 outwards of the housing 10 once the ends 57A of the contacts 57 have been raised out of the recesses 38 to extend through the now aligned apertures 37 in the shutter 30 to engage respective pad electrodes 200 of the inserted bulb. This is illustrated in Fig.

25. All other aspects are identical to those of Figs. 10 to 18.

Referring now to Figs. 26 to 29, there is illustrated a further alternative modified shutter 130' and carrier 150'. In this arrangement, the carrier 150' is provided with two limbs 155' which extend outwardly towards the open end of the housing to engage the shutter 130'. The limbs 155' define a ramp face 156'. Down facing ramps 142', which extend below the inner surface of the shutter 130, allow the carrier 150', and thereby the contacts 157', to move outwards of the housing 110'.

The ramps also provide the means to raise the carrier and contacts 157' back behind the shutter 130'.

In use, as the shutter 130' is rotated by the bulb, a cam on shutter 130' engages a cam follower on actuator (cf 60), moving the actuator 60 transversely of the housing. This action simultaneously effects rotation of the carrier 150' also causing the contacts 157' to be forced inwards of the carrier 150', against the force of the springs 159'. As the ends 157A' of the contacts 157' are forced out of the recesses 138' in the shutter 130', the shutter 130' and carrier 150' are rotated in opposite directions until the limbs 155' move down the ramp faces 142B' on the shutter 130'. This allows the carrier 150', and thereby the contacts 157', to be moved outwards of the housing 110'. The ends 157A' of contacts 157' extend through the now aligned apertures 137' in the shutter 130' to engage respective pad electrodes 200 of the inserted bulb. This is illustrated in Fig. 29. All other aspects of this embodiment are identical to those of Figs. 10, 11 and 13 to 18. Requiring a force to displace the ends 157A' of the contacts 157' out the recesses 138' provides resistance to rotation of the shutter 130' and carrier 150'.

Referring now to Figs. 30 to 32, there is illustrated an arrangement similar to that of Fig. 10, the only difference being that the humps 41 on the shutter 30' have been omitted. Thus, in this embodiment (as with that of Figs. 26 to 29) the ends 57A of the contacts 57 provide resistance to rotation of the shutter 30' and carrier 50. This is because the contacts 57 are required to be depressed inwardly of the carrier 50, against the force of the springs 59 as they are forced out of the recesses 38. The humps 42 provide that the ends 57A of the contacts 57 engage the pad electrodes 180 of the bulb in a desired snap-action manner. All other aspects of this embodiment correspond to those of Figs.

10,11 and 13 to 18.

Referring now to Figs. 33 to 42, there is illustrated a shuttered lampholder comprising a hollow cylindrical housing 310 having "J" slots 311 (comprising an axial portion 312 and a circumferential portion 313).

The housing 310 has a screw thread 316 to retain a shade locking ring.

Support ledges 320 are provided in the housing wall to support a shutter 330. Vertical stop faces 322 and 323 are also defined in the housing wall to limit rotation of a shutter 330 and contact carrier 360 relative to each other and the housing 310. Vertical faces 321 are defined in the housing wall to prevent rotation of the shutter 330 until it has first been moved inwards of the housing 310. A terminal block 380 is supported on the housing ledge 318 and flat faces 317 in the housing prevent relative rotation of the terminal block in the housing 310. The terminal block supports flex engaging terminals 384 which are accessible on opposite sides thereof.

The shutter 330 is mounted in the open end of the housing 310 and comprises a plate or body portion defining a pair of limbs 331 which extend outwards of the housing 310 to the housing "J" slots 311, to locate on support ledges 320. The limbs 331 are provided with slots 332 for engagement with the bayonet pins of an inserted bulb. The housing "J" slots 311 and shutter slots 332 are arranged such that rotation of a bulb causes the shutter slots 332 to rotate with it.

A central boss 336 extends from the inner surface of the shutter 330, and defines a central bore 337. A pair of elongate apertures 333 are provided in the surface of the shutter 330. The walls of the apertures 333 are stepped to provide a contact support surface 334 adjacent each aperture 333 proper. The support surfaces 334 are provided with a dished recess 334A into which the extreme free ends 373 of the contacts 370 locate. This is seen more clearly from Figs 41 and 42. Rotational stops 339 on the shutter 330 engage vertical stop faces 323 defined in the housing wall to limit rotation of the shutter 330.

A rack of gear type teeth 335 are defined on the inner surface at the periphery of the shutter 330. A spring abutment member 338 depends from said inner surface of the shutter to engage one end of a biasing spring 355, as discussed in more detail below.

A contact carrier 360 locates in the housing 310 between the terminal block 380 and shutter 330 and is secured to the shutter 330 by means of a screw 368. The screw 368 engages the stepped aperture 363 in the boss 362 defined centrally on the inner surface of the carrier 360. The screw 368 has a plain band 369 which acts as a stop and spacer and provides that, when the screw 368 is screwed fully into the bore 337 in the shutter, there is clearance between the shutter 330 and carrier 360 to enable them to rotate freely relative to each other.

A pair of spaced, arcuate, contact receiving apertures 361 are diametrically opposed on carrier 360.

A central boss 362 with a stepped aperture 363 extend centrally from the inner surface of the carrier 360. The boss 362 locates in a central bore 386 in the terminal block 380. This ensures that the shutter/carrier assembly is centralised and rotates around a common axis.

The boss 336 on the shutter locates within a bore in the outer surface of the carrier 360.

A rack of gear type teeth 365 are also defined on the periphery of the carrier 360 and arranged to face the rack of teeth 335 on the shutter 330. A formation 367 is provided in the carrier 360 to receive the horizontally arranged biasing spring 355. One end of the spring 355 abuts the stop 366 the other

A pinion wheel 350 is provided, which comprises a plain or smooth body portion 351 with gear teeth formations 352 arranged around the circumference and adjacent body portion 351. The body portion 351 in use engages vertical slot 319 in the housing 310. The pinion wheel 350 is interposed between the shutter 330 and carrier 360 such that its gear teeth are in mesh with the racks of teeth 365 and 335 on the carrier 360 and shutter 330 respectively. The shutter 330, carrier 360, pinion wheel 350 and spring 355 preferably comprise a subassembly which is mounted in the housing 310, with the plain body portion 351 of the pinion 350 engaged in slot 319 in the housing 310. The pinion 350 is free to move inwards and outwards of the housing 310 as the shutter 330 and carrier 360 are moved vertically with respect to the housing. It is also free to turn or revolve within the slot 319 but is prevented from rotating about the axis of the housing 310.

As the shutter 330 is rotated by a bulb on insertion, the teeth 335 on the shutter rack drive the teeth 352 of the pinion wheel 350. This action simultaneously causes the pinion teeth 352 (which are in mesh with the teeth 365 on the carrier rack) to rotate the carrier 360 in the opposite direction to that of the shutter 330. This achieves contramotion which may at the very least double rotational movement of the bulb engaging contacts 370 relative to the shutter 330 for a given rotation of a bulb in the housing 310. This enables contacts of a size that conform with lampholder standards to be readily used and shuttered.

Each bulb engaging contact 370 is a snug, slidable fit in the radial, elongate aperture 361 in the carrier 360. The carrier 360 provides support along the length of the contacts 370. The free ends 373 of the contacts 370 are supported within the recesses 334A in the shutter 330 (see Figs. 41 and 42). The shutter 330 and carrier 360 are rotatable relative to each other between a closed position, in which the apertures 333 and contacts 370 are non-aligned (the contacts 370 in their first position are shielded by the formations 367 depending from the outer surface of the shutter 360), and an "open" position in which the apertures 333 are aligned with the bulb engaging contacts 370. The contacts 370 slidably extend through the apertures 333 to engage respective pad electrodes 180 of an inserted bulb.

The radial width of the shutter apertures 333 is selected such that they will not allow the contacts 370 to pass completely therethrough. The angled faces 372 of the contacts 370 abut the edge of the apertures 333.

Adjacent the support surface 334 the angled faces 372 of the contacts 370 enable the shutter 330 to move the contacts back through the apertures 333, against the force of the bridging springs 375. As the shutter 330 and carrier 360 are rotated from their second back to their first position, assisted by the spring 355 on bulb removal, the contacts 370 (via the springs 375) act to bias the shutter assembly outwards of the housing 310 into the first locking position, in which the limbs 331 locate on the support ledges 320 in the housing wall.

The rotationally biasing spring 355 may be arranged to act between the housing 310 and shutter 320 to bias the shutter means to a "closed" position. Alternatively, spring 355 may act between the housing 310 and the carrier 360 to bias the shutter means.

In use, when the lampholder of Figs. 33 to 42 is assembled, and with no bulb present, the components assume the position illustrated in Figs. 35, 36 and 41.

The shutter slots 332 are aligned with the axial portion 312 of the "j" slots 311 and the contacts 370 are located behind the inner surface of the shutter 330, their free ends 373 being seated in the recesses 334A and shielded by the formations 367. Thus, the contacts 370 are inaccessible and not visible behind the shutter 330. The shutter 330 (and thereby the shutter assembly) is biased outwards of the housing 310 against the support ledges 320 by the loaded contacts 370. The shutter 330 and carrier 360 are rotationally biased relative to each other to their "closed" position by the spring 355. The ends of the limbs 331 abut the stop face 321 to lock the carrier against rotation.

Insertion of a bulb is done in two stages, an axial stage and a rotational stage. As a bulb is inserted axially into the lampholder the bayonet pins engage the aligned slots 311 and 332 and the pad electrodes 180 of the bulb abut against the outer surface of the shutter 330 to move the shutter assembly inwards of the housing 310 against the force of the loaded contacts 370. This action unlocks the shutter 330 (and thereby the carrier 360) to be rotated within the housing 310. This also frees the pinion wheel 350 to turn within the slot or keyway 319 in the housing wall. When the bayonet pins reach the end of the axial slot 312 the lampholder components assume the position illustrated in Fig. 37 after this axial stage of bulb insertion.

Rotation of a bulb in the lampholder causes the shutter 330 to rotate with it from its "closed" to its "open" position. This action simultaneously causes the teeth 335 on the shutter rack to drive the teeth 352 to turn the pinion 350. The pinion 350 (via its teeth 352 which are in mesh with the carrier teeth 365) also rotates the carrier 360 in the opposite direction to the shutter 330. The rotation of the shutter 330 is against the force of the spring 355. This aligns the apertures 333 with the contacts 370 such that the ends 373 of the contacts 370 slidably extend through the apertures 333, moved by the force of the springs 375 to engage the pad electrodes 200 of the inserted bulb. The lampholder components assume the "on" position best illustrated in Figs. 38 and 42 when a bulb is fully inserted.

As the shutter 330 and thereby the carrier 360 (via the pinion wheel 350) are rotated by the bulb on bulb removal, assisted by the spring 355, from their second "open" position back to their "closed" position, the edge of the support surface 334 engages the angled face 372 of the contacts 370. This readily moves the contacts 370 inwards of the housing 310 against the force of the springs 375. The ends 373 of the contacts 370 are moved back through the apertures 333 to be relocated behind the shutter 330 in the recesses 334A. The shutter 330 thus assumes its "closed" position, as shown in Fig. 41.

As the bulb is removed axially from the lampholder the loaded contacts 370 move the shutter sub-assembly outwards of the housing 310. The limbs 331 locate on the support ledges 320 and the lampholder components assume their first position best illustrated in Figs. 35, 36 and 41, in which position the shutter means is locked against rotation relative to the housing.

Referring now to Figs. 43 and 44, there is illustrated a lampholder similar to the embodiment of Figs. 33 to 42, modified to incorporate a transverse switchbar 390. The switchbar 390 supports a pair of bridging contacts 398 which are electrically connected to the bulb engaging contacts 370 via bridging springs 375.

The switchbar 390 is manually movable transversely of the housing 310 between an "off" position (as illustrated in Fig. 43), in which there is no electrical connection between the pair of bridging contacts 398 and respective flex terminals 384 in the terminal block 380, and an "on" position, in which the bridging contacts 398 engage the terminals 384 to make an electrical connection.

A cam formation 394 is defined on and depends from the surface of the switchbar 390 which faces the carrier 360. The cam formation 394 is arranged to be engageable by an upstanding cam follower 367 extending from the periphery of the inner surface of the carrier 360. Prior to bulb insertion the switchbar 390 is in its "off" position and is locked against transverse movement relative to the housing 310 by the cam follower 367, until a bulb is axially inserted and rotated in the lampholder.

As the carrier 360 is rotated by a bulb, the cam follower 367 is moved clear of the cam 394 unlocking the switchbar 390 to be moved transversely between its two positions in order to manually switch the lampholder "on" and "off" in conventional manner. The bridging contacts 398 are forced over switching humps 390 defined on the inner surface of the terminal block 380 to engage and disengage respective terminals 384 in a snap-action fashion. Should a bulb be removed from the lampholder when the switchbar 390 is in the "on" position, the cam follower 367 will engage the cam 394 and automatically move the switchbar 390 transversely of the housing 310 from its "on" back to its "off" position. The cam follower 367 will relocate in front of the switchbar to obstruct transverse movement, locking the switchbar 390 in its "off" position until a bulb is once again inserted.

Thus the proposed manually switchable lampholder will always be in the "switched off" position when a user inserts a bulb.

An elongate aperture 392 is provided centrally in the switchbar 390 through which the modified screw 368A passes to locate in the bore 387 in the terminal block 380. The modified screw 368A provides that the shutter means 330, 360(or shutter sub-assembly) rotates around a common axis. Alternatively, should the shutter 330 and carrier 360 be secured together by, for example, snapengaging means, a centralising peg may be defined on the inner surface of the carrier 360 to engage the bore 387 in the terminal block 380.

Guide ribs 393 are defined on the upper surface of the switchbar 390 to engage in a channel 386 in the terminal block 380. Slots 324 are provided in the housing wall through which the limbs 391 of the switchbar extend so as to be accessible to the user.

Referring now to Figs. 45 to 48, there are illustrated views of a lampholder similar to that of the embodiments of Figs. 33 to 42, modified to incorporate a locking peg 400. The peg 400 is supported by the housing 310 and is biased to a locked position in which it prevents rotational movement of the shutter means from its "closed" to its "open" position. The locking peg 400 is arranged such that it is engaged by an inserted bulb so as to be moved by the bulb to an unlocked position, in which the carrier 360 and shutter 330 are free to be moved from "their" closed to their "open" position.

The locking peg 400 is engaged by an inserted bulb so as to be moved to the unlocked position as a bulb is axially inserted into the lampholder and prior to rotation of the bulb.

Preferably, the locking peg 400 defines an angle or ramp formation 404 which interengages a corresponding ramp form 420 on a carrier 360A. This may provide that the locking peg 400, on bulb removal, will act to bias the carrier 360A and thereby the shutter means, moving the shutter means from its "open" back to its "closed1' position and lock the shutter sub-assembly in its "closed" position, The locking peg 400 is biased to a locked position by a compression spring 410, one end of which locates in a bore 430 in the terminal block 380A. The other end of the spring 410 engages a boss 403 on the peg 400. The body portion 401 of the peg 400 extends to adjacent the open end of the housing 310 in a slot 319A to locate on a ledge 320A so as to be engageable by the shoulder of the bulb. Cut outs 440 and 441 are provided in the periphery of the body portions of the shutter 330A and carrier 360A respectively to enable them to rotate relative to the peg 400. A rib 402 on the peg 400 is engaged by the shoulder of the bulb in order to raise the peg 400 to its unlocked position, and prior to the bulb electrodes 180 engaging the outer surface of the shutter 330A. A vertical face 405 at the foot of the ramp 404 provides the locking means.

In this arrangement the rotationally biasing spring 355 may be dispensed with as the peg 400 will rotate the carrier 360A, which via the pinion wheel 350 will rotate the shutter 330A biasing the shutter means to its "closed" position.

The incorporation of such a locking peg will make it even more difficult for a child to defeat the shutter mechanism.

It will be appreciated that various modifications may be made to the illustrated embodiments.

Claims (20)

1. A safety lampholder for a bayonet bulb comprising a body defining slots to receive bayonet pins of an inserted bulb, bulb engaging contacts within the body for electrical connection to a power source to supply electricity to the bulb and shutter means in the body for selectively obstructing access to the contacts, the shutter means comprising apertured shutter members capable of relative rotation about a common axis between a first position in which their apertures are obstructed and a second position in which they are aligned and arranged so that rotation of a bulb actuates rotation of a first shutter member, means being provided in the housing for actuating contrarotation of a second member between a first inoperative position in which the contacts are shielded by at least one of the shutter members and a second operative position in which they extend through aligned apertures in both shutter members for bearing against a bulb.

2. A safety lampholder according to Claim 1 wherein the apertured shutter members are axially moveable within the lampholder body.

3. A safety lampholder according to Claim 2 wherein locking means are provided for inhibiting rotation of at least the first shutter member until it has been displaced axially inwardly of the lampholder body.

4. A safety lampholder according to Claim 3 wherein the locking means are arranged to be releasable by an inserted bulb.

5. A safety lampholder according to any one of claims 2 to 4 wherein means are provided for biasing at least the first shutter member outwardly of the housing.

6. A safety lampholder according to Claim 5 having resilient bulb engaging contacts which bias the first shutter member outwardly of the housing.

7. A safety lampholder according to any preceding claim wherein the means for actuating contrarotation of the second shutter member are driven by rotation of the first shutter member.

8. A safety lampholder according to any preceding claim wherein the means for actuating contrarotation of the second shutter member comprise circumferentially spaced formations on opposing surfaces of said first and second shutter members and a displaceable member located between said first and second shutter members so as to be rotatable about an axis perpendicular to the common axis of rotation of the shutter members, said displaceable members having formations interengageable with shutter member formations and arranged such that rotation of a first shutter member by a bulb is effective to drive rotation of the displaceable member to actuate rotation of the second shutter member in the opposite direction to the first shutter member.

9. A safety lampholder according to Claim 8 wherein means are provided for inhibiting rotation of the displaceable member about the axis of rotation of the first and second shutter members.

10. A safety lampholder according to Claim 8 or 9 wherein the displaceable member is in the form of a gear wheel.

11. A safety lampholder according to any preceding claim wherein means are provided for preventing relative axial movement of the first and second shutter members.

12. A safety lampholder according to any preceding claim wherein the means for actuating contrarotation are manually operable.

13. A safety lampholder according to Claim 12 wherein the means for actuating contrarotation include a member moveable transversely with respect to the lampholder body, the transversely moveable member having formations interengageable with formations on the second shutter member and arranged such that transverse displacement of the transversely moveable member is effective to drive contrarotation of the second shutter member.

14. A safety lampholder according to Claim 13 wherein the transversely moveable member and first shutter member have interengageable formations arranged such that rotation of the first shutter member is effective to drive transverse displacement of the transversely moveable member.

15. A safety lampholder according to Claim 13 or 14 wherein the transversely moveable member has limbs which extend laterally beyond the lampholder body, to provide a manually operable switch bar for making and breaking the electrical connection to an inserted bulb.

16. A safety lampholder according to any one of claims 13 to 15 wherein the second rotatable shutter member acts as a contact carrier and is arranged to be axially moveable upon transverse displacement of the transversely moveable member to displace the contacts inwardly and outwardly of the lampholder body to make and break the electrical connection to an inserted bulb.

17. A safety lampholder according to any one of claims 13 to 16 wherein power supply terminals and bulb engaging contacts are supported in the housing and a pair of bridging contacts are carried by the transversely moveable member to effect an electrical connection between the terminals and bulb engaging contacts, the transversely moveable member being displaceable to displace the bridging contacts to make and break the electrical connection to an inserted bulb.

18. A safety lampholder according to Claim 16 or 17 wherein the carrier and first shutter member have interengageable formations arranged such that rotation of the first shutter member is effective to drive axial displacement of the carrier inwardly and outwardly of the housing between a first inoperative position in which the contacts are located behind the first shutter member and a second position in which the contacts are aligned with and extend through apertures in the first shutter member.

19. A safety lampholder according to any preceding claim wherein the first shutter member has recesses alongside its apertures for accommodating the contacts when the lampholder is in the first inoperative position.

20. A safety lampholder substantially as hereinbefore described with reference to, and as illustrated in, any one of the accompanying Figures 1 to 40.