AU671699B2

AU671699B2 - Safety lampholder for a bayonet bulb

Info

Publication number: AU671699B2
Application number: AU55323/94A
Authority: AU
Inventors: Terence Hartley
Original assignee: Gerard Industries Pty Ltd
Current assignee: Clipsal Australia Pty Ltd
Priority date: 1992-11-25
Filing date: 1993-11-25
Publication date: 1996-09-05
Anticipated expiration: 2013-11-25
Also published as: AU5532394A; WO1994013041A1; HK63097A; MY110097A; NZ257902A

Description

SAFETY LAMPHOLDER FOR A BAYONET BULB

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

Safety lampholders have been proposed in which removal of a bulb from the lampholder causes an internal mechanism to isolate the bulb engaging contacts from the live flex terminals. Examples of such lampholders are disclosed in French Patent No. 2403665, US Patent 4,461,523 and German Patent 2651334. In such lampholders a shutter mechanism may be used to place a shutter between a socket defined by the lampholder for receiving a bulb, and contacts which when a bulb is inserted bear against the contact pads of that bulb.

In the safety lampholder structure of DE Patent No. 2651334 the bayonet pins of an inserted bulb engage in recesses defined by the shutter during the initial axial movement of the bulb, and the shutter is then driven by the bulb bayonet pins as the bulb is rotated into its final resting position. This rotation of the shutter moves apertures in the shutter into alignment with telescopic spring flex contacts supported by the lampholder. The contacts thus spring through the apertures into engagement with the contact pads of the bulb. However, it has been found in practice that with the above mentioned arrangement, the telescopic spring loaded flex terminals become embedded in the bulb pad contacts, which action locks the shutter against rotation and prevents bulb removal. Also, difficulties arise in getting the contacts back behind the shutter. Furthermore, even when the contacts are behind the shutter, it is still possible for a wire or the like to be inserted through the apertures in the shutter by for example an inquisitive child.

The present invention seeks to overcome such problems by providing an improved safety lampholder. In particular, the present invention seeks to provide an effective way of drawing contacts behind the shutter on removal of the bulb.

Accordingly, in a broad aspect, the present invention provides a safety lampholder for a bayonet bulb comprising a hollow, generally cylindrical housing defining slots at one end thereof to receive bayonet pins of an inserted bulb, bulb engaging contacts within the housing for electrical connection to a power source to supply electricity to the bulb, apertured shutter means located within the housing for selectively obstructing access to the contacts and arranged such that insertion and removal of an inserted bulb actuates relative movement of the contacts and shutter means between a first inoperative (or "closed") position in which the contacts are and obstructed by the shutter means and a second operative (or "open") position in which the contacts extend through the apertures in the shutter means to bear against an inserted bulb, interengageable surface formations being provided within the housing for actuating displacement of the contacts and arranged such that, upon rotation of an inserted bulb, the contacts are displaced inwardly of the housing and raised from their first position and lowered through apertures in the shutter means into their second position, and upon removal of a bulb the contacts are raised back through the apertures in the shutter means and lowered into their first position. Preferably, in their first position the contacts are offset from apertures in the shutter means.

Suitably the contacts assume their first position when the bulb is removed and their second position when the bulb is fully inserted.

Conveniently, power supply terminals are supported in a closed end of the housing at its end remote from the bulb receiving end and the bulb engaging contacts are electrically connected to the power supply terminals by flexible, suitably resilient, conducting elements. Conveniently the power supply terminals may be located in a terminal block, fixedly mounted in the housing so that it cannot rotate with respect to the housing. Particularly preferred flexible conducting elements comprise coil springs. Preferably the bulb engaging contacts are biased outwardly of the housing by the flexible conducting elements.

In preferred embodiments such hollow cylinders may accommodate a flexible conducting element as described above.

In some preferred embodiments the bulb engaging contacts are located in an axially moveable contact carrier capable of actuating displacement of the contacts between their first and second positions. The contact carrier is located in the housing between its closed end and the shutter means. Preferably the contact carrier engages the contacts to achieve displacement thereof upon rotation of an inserted bulb. Suitably the contact carrier has apertures which are smaller than enlarged heads of the contacts so that the carrier can engage the contacts.

Preferably any such contact carrier is biased outwardly of the housing. In particularly preferred embodiments the contact carrier is biased outwardly of the housing by the contacts, including their resilient conducting elements.

In some preferred embodiments of the invention, a rotatable generally cylindrical member is mounted in the housing and extends to the housing slots and defines slots for engagement with the pins of an inserted bulb, the housing slots and rotatable member slots being arranged such that insertion of a bulb causes the rotatable member to rotate from a first to a second position and removal of the bulb causes the rotatable member to rotate from the second to the first position. In this regard, suitably the housing slots are so-called J-slots having an axial portion and a circumferential portion. Preferably the rotatable member has axial slots for engaging bulb pins.

In some preferable embodiments an axially movable contact carrier is located in the housing and surface formations are provided on the contact carrier and arranged to interengage with surface formations on a rotatable member such that rotation of the rotatable member drives axial displacement of the contact carrier and displaces the contacts between their first and second positions. The rotatable member may be apertured to provide the shutter means. Alternatively a different component may provide the shutter means. In this respect preferably the rotatable member drives rotation of a shutter means, or alternatively the contacts.

In embodiments of the invention, the shutter means are axially movable with respect to the housing. In some preferred embodiments the shutter means are axially movable between first and second positions and which provide locking means such that when the shutter means are in their first position movement of the rotatable member is obstructed and when the shutter means are in their second position movement of the rotatable member is permitted. If the shutter means are axially movable with respect to the housing, preferably they are biased outwardly of the housing. In particularly preferred embodiments the shutter means are biased outwardly of the housing by resilient bulb engaging contacts. Alternatively, separate biasing means may act between the shutter means and the housing, suitably between a terminal block and the shutter means.

In some embodiments of the present invention the bulb engaging contacts are accommodated in recesses in the shutter means when in their first position.

Preferably such recesses are alongside the apertures in the shutter means. Preferably means are provided for shielding the contacts from the apertures in the shutter means particularly when the contacts are located in such recesses in the shutter means. Such shielding means may comprise surface formations on the shutter means or another component of the lampholder. In preferred embodiments the shielding means comprise annular skirts which depend from a contact carrier at or near the apertures in the carrier.

In some embodiments of the present invention the housing includes a bridge member having arcuate slots which accommodate limbs of a rotatable member to permit rotation thereof between first and second position the bridge member also having a pair of apertures to permit passage of bulb engaging contacts therethrough to bear against an inserted bulb. In this respect, preferably surface formations are provided on the housing (in the walls of the housing or on the bridge member) to drive axial displacement of the contacts between their first and second positions. In such embodiments preferably the contacts are rotatable by a rotatable member with respect to the bridge member such that the bridge member provides a shutter means. In other embodiments a different component i the lampholder provides the shutter means. In such embodiments preferably the shutter means is both rotatably and axially movable with respect to the housing. In this way the shutter means may effect axial displacement of the contacts/contact carrier.

The surface formations which actuate axial displacement of the contacts ( including a contact carrier, if appropriate), may take various forms. Preferably the interengagable surface formations comprise opposing hump formations. Thus,one component of the lampholder may include a hump formation extending inwardly of the housing and another component may include a hump formation extending outwardly of the housing.

Preferably the surface formations are provided at or near the internal peripheral wall of the housing. In particularly preferred embodiments a hump formation comprises a first ramp face and a second ramp face of a length different to that of the first ramp face. Preferably such humps or other surface formations are circumferentially spaced within the housing.

In addition to the interengagable surface formations for driving axial displacement of the contacts, other surface formations may be located within the housing. In cases where the lampholder includes several rotatable components, for example, it may be desirable to include means for ensuring that the components rotate about a common axis. For example, a centralising peg may be included on one component for accommodation in a central aperture in another component. Alternatively or in addition surface formations may also be provided to guide axial displacement of any of the components, and/or to prevent relative rotation of certain components. Example preferred such formations include projections or keys on a first component which is axially movable within a slot or channel cr keyway in a second component. In addition, surface formations in the form of ledges may be provided on the internal wall of the housing for retaining components of the holder inside the housing.

Embodiments of the present invention will now be described further, by way of example, with reference to the accompanying drawings in which:

Fig. 1 is an exploded view of a lampholder according to a first embodiment;

Figs. 2 to 5 are cross-sectional views of the Fig. 1 lampholder, illustrating the position of the components after various stages of bulb insertion;

Figs. 6 to 8 are exploded sectional views of a part of the Fig. 1 lampholder, illustrating the position of the components after various stages of bulb insertion;

Figs. 9 and 10 are cross-sectional views of a second embodiment;

Fig. 11 is an exploded view of a third embodiment;

Figs. 12 and 13 are cross-sectional views of the Fig. 11 lampholder, illustrating the position of the components after different stages of bulb insertion;

Figs. 14 to 17 are cross-sectional views of a fourth embodiment, illustrating the position of the components after different stages of bulb insertion; Fig. lc is a plan view of the lampholder housing of the fourth embodiment;

Fig. 19 is a cross-sectional view of a modified version of the embodiment of Figs. 14 to 17;

Figs. 20 to 23 are cross-sectional views of a fifth embodiment, illustrating the position of the components after different stages of bulb insertion;

Figs. 24 and 25 are cross-sectional views of a modified version of the Fig. 20 to 23 embodiment;

Figs. 26 to 28 are cross-sectional views of a sixth embodiment, illustrating the position of the components after different stages of bulb insertion.

Fig. 29 is a cross-sectional view of the sixth embodiment modified to include a transverse switchbar;

Figs. 30 and 31 are cross-sectional views of a seventh embodiment, illustrating the position of the components after different stages of bulb insertion;

Figs. 32 to 47 are cross-sectional views of an assembled lampholder according to an eighth embodiment and views of the various lampholder components;

Figs. 48 to 53 are cross-sectional views of an assembled lampholder according to an eighth embodiment, illustrating the position of the components after different stages of bulb insertion.

Figs. 54 to 57 are cross-sectional views of an assembled lampholder according to a further embodiment, illustrating the position of the components after different stages of bulb insertion.

Referring now to Figs. 1 to 8, there is illustrated a shuttered lampholder comprising a hollow cylindrical housing 10 into one end of which can be received the cap of a bayonet type bulb. The housing 10 is provided with the usual "J" slots 11 to receive the respective bayonet pins of a bulb. The slots 11 include an axial portion 12 and a circumferential portion 13. The housing 10 is also provided with a screw thread 15 to accept a threaded locking ring 80. This is used to secure a cover 90 onto the top of the housing 10 so as to cover the terminal 65 whilst providing an entry port 92 for the power supply flex. The thread 15 also acts to retain a shade locking ring.

An annular support ledge 17 is provided internally at the open end of the housing 10 to support a shutter 20. Formations/indentations are defined in the housing wall (not illustrated) to engage the shutter 20 and prevent rotation of the shutter relative to the housing 10 until said shutter 20 has first been moved inwards of the housing 10 on axial insertion of a bulb, to be described in more detail below.

The end of the housing 10 opposite the bulb receiving end is closed by a terminal block 60 which is secured in fixed relation to the housing 10 by formations 16 and 16A. The formations 16 engage in undercuts 69 in the terminal block 60. The terminal block 60 supports a pair of resilient terminal contacts which each comprise a flex engaging terminal 65 and a bulb engaging contact 40 which are connected by a bridging spring 50 (see Fig. 2) . The bulb engaging contacts 40 comprise hollow metal cylinders having a reduced diameter at 43 providing a step 41. They are closed at end 43. Their other ends are open and flared at 42. The terminal contacts are located within bores 63 in the terminal block 60 and extend through the terminal block 60 so as to be accessible on opposite sides thereof. A slot 67 is provided centrally in the inner surface of the terminal block 60 to receive limb 39 which extends from the inner surface of the contact carrier 30 to prevent relative rotation.

A shutter 20 is located in the open end of the housing 10 which is the bulb receiving end, and comprises a base surface 27 with a peripheral skirt or wall portion 21. The wall portion 21 extends to the housing "J" slots to locate on the support ledge 17 defined internally at the mouth of the housing 10. The wall portion 21 also includes slots 22 for engagement with the bayonet pins of an inserted bulb.

Surface formations are provided on the wall of the housing 10 so that axial insertion of a bulb is required to cause the shutter 20 to be moved inwards of the housing 10 to an unlocking position, in which it is free to be rotated by the bulb. The housing "J" slots 11 and shutter slots 22 are arranged such that rotation of a bulb on insertion causes the shutter 20 to rotate with it. A pair of spaced elongate apertures 23 are provided in the surface 27 of the shutter 20. Each aperture has an arcuate ledge or stepped portion 26 and a dished well or recess 25. At least two hump formations 24 are also defined on the perimeter of the shutter. The formations 24 comprise a short ramp face 24A and a longer ramp face 24B. A central bore 29 is also provided in the inwardly facing surface of the shutter 20 to receive a centralising peg 33 defined on the outer surface of a contact carrier 30. The shutter 20 is capable of adopting an "open" position in which apertures 23 are aligned with the bulb engaging contacts and a "closed" position in which the apertures 23 and contacts 40 are not aligned. Rotation of a bulb on insertion causes the shutter 20 to rotate from its closed to its open position and removal of a bulb causes the shutter 20 to rotate from its open back to its closed position.

A contact carrier 30 locates in the housing 10 in the gap defined between the terminal block 60 and shutter 20. The carrier 30 is arranged so that it can only move axially with respect to the housing 10. The contact carrier is provided with a pair of spaced apertures 31, each having a step 32 to engage a shoulder 41 of the contacts 40. An annular skirt 36 extends around the aperture 31 with a depending limb 37, to shield the contacts 40 when a bulb is removed from the lampholder. Fig. 8 illustrates in more detail how the annular skirt 36 and depending limb 37 move into the aperture 23 of shutter 20 in the operative position of the lampholder.

A limb 39 is defined on and extends from the inner surface of the contact carrier 30 to locate in the slot 67 in the terminal block. At least two downwardly directed and generally triangular hump formations 34 are provided on the periphery of the inner surface of the carrier 30 to interengage corresponding hump formations 24 on the shutter 20. The interengagable formations 24, 34 provide that as the shutter 20 is rotated on bulb insertion from its closed to its open position it moves the contact carrier 30 axially inwards of the housing 10 as the hump 34 rides up the short or "off" side 24A of the hump 24, and outwards of the housing 10 as the humps 34 move down the longer or "on" side 24B of the humps 24. As the shutter 20 is rotated on bulb removal from its open back -o its closed position it moves the contact carrier 30 inwards of the housing as the humps 34 ride up the "on" side 24B of the humps 24, and outwards of the housing as the humps 34 move down the "off" side 24A of the humps 24.

The flared end 42 of a bulb engaging contact is located on a step 64 in the bore 63 in terminal block 60. The other end of the bore 63 is closed by the flex engaging terminal 65 which is secured in fixed relation to the terminal block. A bridging spring 50 is interposed between the bulb engaging contact 40 and terminal 65. The spring 50 provides a resilient electrical connection between the contacts 40 and terminals 65 and allows the contact 40 to be depressed against the force of the springs 50 inwards of the bore 63. The contacts 40 extend from the inner surface of the terminal block 60 with their narrow ends 43 extending through the apertures 31 in the carrier 30 such that their shoulders 41 locate on the respective steps 32 in the apertures 31. The contacts 40 thereby act to bias the carrier 30 outwards of the housing 10 and against the shutter 20 and thus the shutter 20 against the support ledge 17.

In use with the lampholder of Figs. 1 to 8 assembled and with no bulb present, the lampholder components assume the position illustrated in Fig. 2 and 6. The slots 22 are aligned with the axial portion 12 of the "J" slots 11. The contacts 40 are each located behind the outward face of the shutter 20 in a dished recess 25 and shielded by the skirt 36 and limb 37 of the contact carrier 30. The carrier 30 is biased outwards of the housing 10 by the contacts 40. Thus the humps 34 on the carrier 30 are biasing the shutter 20 outwards of the housing 10 and against the support ledge 17. At this stage, the humps 34 are located on the "off" side 24A of the hump formation 24 and the shutter 20 is therefore in its first closed position and the contacts 40 are not visible nor accessible. The shutter 20 is also locked 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 12 and 22 and the pad electrodes 100 of the bulb abut against the outer surface of the shutter 20 moving the shutter 20 and thereby the carrier 30 inwards of the housing 10, against the combined force of the loaded contacts 40, until the bayonet pins reach the end of the slots 12 and the lampholder components assume the position illustrated in Figs. 3 and 6. After this axial stage of bulb insertion the shutter 20 is now in its unlocked position and free to be rotated in the housing.

Rotation of the bulb causes the shutter 20 to rotate with it and thereby the humps 34 on contact carrier 30 to ride up the "off" faces 24A of the humps 24. This action moves the carrier 30 axially inwards of the housing 10, raising the contacts 40 out of the dished recesses 25, and further loads the springs 50. The lampholder components thus assume the position best illustrated in Figs. 4 and 7. After this partial rotation of the bulb the apertures 23 in the shutter 20 move inτo alignment with the contacts 40.

On continued rotation of the bulb, the humps 34 on carrier 30 move down the "on" side 24B of the humps 24, which causes the contacts 40 to move the carrier 30 outwards of the housing 10. The ends 42 of rhe contacts 40 extend through the now aligned apertures 23 in the shutter 20 to engage respective pad electrodes 100 of the inserted bulb. This "on" position is illustrated in Figs. 5 and 8.

As the shutter 20 is fully rotated to its open position the skirt 36 on contact carrier 30 moves into the stepped portion 26 alongside the aperture 23 and the limb 37 move into the aperture 23. The "on" sides 24B of the hump 24 are longer than the "off" sides 24A and extend further outwards of the housing. Thus the carrier 30 is allowed to move further outwards of the housing in its on position in order for the contacts 40 to extend past the outer surface of the shutter 20 to engage the pad electrodes 100 of the bulb.

As the shutter 20 is rotated by the bulb on removal the bayonet pins move along the horizontal portion 13 of the "J" slots 11 causing the humps 34 to ride up the "on" side 24B of the humps 24 and thereby the carrier 30 is moved inwards of the housing 10 against the force of the loaded contacts 40. The contacts 40 are moved back through the apertures 23 and are re-located in the dished recesses 25. As the humps 34 reach the bottom of the "on" humps 24A, the shutter assumes its closed position with the contacts 40 behind the shutter 20 and shielded by the skirts 36 and limbs 37 respectively. At this stage the lampholder components assume the position illustrated in Figs. 3 and 6. As the bulb is removed axially from the lampholder the loaded contacts 40 move the carrier 30 and thereby the shutter 20 outwards of the housing 10 to their respective first positions. The shutter 20 relocates against the support ledge 17 and the components assume the position illustrated in Fig. 2 in which the shutter 20 is locked against rotation relative to the housing.

Referring now to Figs. 9 and 10 there is illustrated another embodiment of the present invention. The figures are sectional views of a lampholder with a plastic housing 110. The principle of operation is essentially the same as for the previous embodiment, which is preferably fabricated from metal. Making a lampholder out of metal allows a thin wall section to be used. This made it possible to have a peripheral wall 21 on the shutter 20 which extended to adjacent the open end of the housing. However, in this embodiment, the wall of the plastic housing 110 can suitably only be reduced in thickness locally and to adjacent the horizontal portion 113 of the "J" slot. This leaves full material thickness beneath the horizontal portion 113 of the "J" slot as this is a potential weak point. Therefore, in the embodiment of Figs. 9 and 10, a shutter 120 is provided in the form of a disc having aperturing 123. The shutter 120 has humps 124 and central bore 129 generally as in the previous embodiment. Lugs 128 extend outwardly from the edge of the shutter to engage vertical slots 119 in the housing 110 and locate on support ledges 118. The slots 119 define a stop face 116. Interengagement of lugs 128 and slots 119 prevents rotation of the shutter 120, until the shutter 120 is raised clear of step face 116.

As with the previous arrangement a carrier 130 locates on the shutter 120 and the carrier 130 is biased outwards of the housing by the resilient terminal contacts 140 thereby biasing the shutter 120 outwards and against the support ledges 118. A cylindrical rotatable member 170 locates in the housing between the terminal block 160 and carrier 130 and defines a pair of limbs 171 which extend therefrom to the housing "J" slots to locate on support ledges 117. The limbs 171 are provided with axial slots 172 for engagement with the bayonet pins of a bulb. A pair of vertical keys or projections 174 are provided internally on the limbs 171 which engage in elongate keyways in the shutter 120 and provide that, as the rotatable member 170 is rotated by the bulb, it moves the shutter 120 with it. Before the shutter 120 can be rotated it must first be moved inwards of the housing 110 in order that the lugs 128 are raised clear of the stop face 116 in the slots 119.

In use when the lampholder of Figs. 9 and 10 is assembled and with no bulb present the lampholder components assume the position illustrated in Figs. 9 and 6. The slots 172 in the rotatable member 170 are aligned with the axial portion 112 of the slots 111. The contacts 140 are located behind the shutter 120 in dished recesses (not illustrated) and are shielded by a skirt 136 and depending limb of the carrier 130 (as in the previous embodiment) . The carrier 130 is also biased outwards of the housing 110 by the contacts 140. Thus, the humps 134 on the carrier 130 bias the shutter 120 outwards of the housing 110 and against the support ledges 118, when the humps 134 are located on an "off" side 124A of humps 124. The shutter is therefore in its closed position and the contacts 140 are inaccessible and the shutter 120 is locked- against rotation.

As a bulb is inserted axially into the lampholder the bayonet pins move into the aligned slots 112 and 172 and the pad electrodes 100 of the bulb engage the shutter 120 moving it and carrier 130 inwards of the housing 110, against the force of the loaded contacts 140, until the bayonet pins reach the end of the slots 112. At this stage the lugs 128 have been raised clear of the stop faces 116, freeing the shutter to be rotated in the housing 110.

Rotation of the bulb causes the rotatable member 170 to rotate with it which also causes the shutter 120 to rotate. The humps 134 on the contact carrier 130 respectively ride up the "off" faces 124A of humps 124 on the rotating shutter 120, moving the carrier 130 axially inwards of the housing 110. This also raises the contacts 140 out the of dished recesses in the shutter 120 and further loads the contacts 140 until the humps 134 move down the "on" side 124B of the humps 124. This causes the contacts 140 to move the carrier 130 outwards of the housing 110 and the ends 142 of said contacts 140 extend through the now aligned apertures 123 in the shutter 120 to engage their respective pad electrodes on the end of the bulb. The lampholder components assume the "on" position illustrated in Fig. 10.

On removal of a bulb the rotatable member 170 rotates the shutter 120 from its open back to its closed position. All other aspects of this embodiment are similar to that of Figs. 1 to 8. Components of this embodiment which are similar to those of the previous embodiments are designated by similar reference numerals advanced by 100.

Referring now to Figs. 11 to 13 there is illustrated an alternative arrangement in which a shutter 220 moves axially inwards and outwards with respect to the housing. This is because the shutter 220 has lugs 228 to engage in the axial or vertical slots 219 in the housing wall and be supported on ledges 218 also in the housing wall. Hump formations 224 and 234 respectively are defined on the shutter 220 and carrier 230. In this embodiment it is the carrier 230 which is rotatable with respect to the housing 210.

As discussed above the carrier 230 is provided with lugs 238 which engage in the vertical body slots 219. A stop face 216 of the slots 219 prevents rotation of the carrier 230 until it has first been moved inwards of the housing. As with the previous embodiment of Figs. 9 and 10 an additional rotatable member 270 is provided to engage the carrier 230. The carrier 230 locates within cutouts 273 in the rotatable member 270. The member 270 also defines limbs 271 having axial slots 272 which extend to the housing "J" slots 211 so as to be engageable by a bulb. The arrangement provides that, as the rotatable member 270 is rotated by the bulb, it rotates the carrier 230 with it from a first to a second position causing the humps 234 on the contact carrier 230 to ride up the "off" side 224A of the humps 224 and down the "on" side 224B of humps 224. This action moves the carrier 230 firstly inwards of the housing 210, to raise the contacts out of the cup shaped recesses 225 and then outwardly of the housing as the humps 234 move down the "on" side 224B of the humps 224. The contacts 240 now extend through the aligned apertures 223 in the shutter 220 to engage respective the pad electrodes of an inserted bulb. The component thus assume the position illustrated in Fig. 13.

In this arrangement the bulb engaging contacts are supported by the contact carrier 230 within stepped apertures 231. The enlarged heads 242 of the contacts 240 locate on a step 232 in the carrier 230. The end of a bridging spring 250 locates within a bore 244 in each contact 240. The other end of the spring 250 locates in an aperture 263 in the terminal block 260 and engages the terminal 265. This provides an acceptable electrical bridging connection between the pairs of bulb engaging contacts 240 and flex engaging terminals 265 and accommodates the movement axially and rotationally of the contacts 240 with respect to the terminals 265. Fig. 12 illustrates how the rotatable member 270 is prevented from rotating until the shutter 220 has first been moved inwards of the housing 110 by the end of the bulb to raise the lugs 238 on the carrier 230 above the stop face 216.

Figs. 14 to 18 show another embodiment of the present invention. As before, this concerns a lampholder which comprises a hollow cylindrical housing 310 having "J" slots 311.

The other end of the housing 310 is closed by a terminal block 360 which is fixed relative to said housing 310. A terminal contact housing 362 depends from the inner surface of the terminal block 360 and comprises a pair of bores 363 to house resilient terminal contact assemblies. Each assembly consists of a terminal 365, a bridging spring 364 and a bulb engaging contact 366. The contacts 366 are of generally cylindrical form, closed at one end 367 and retained in the terminal block 360 by means of shoulders 369. One end of each spring 364 locates on the contacts 366 and the other end within the terminal 365. Springs 364 thus provide a resilient electrical bridging connection between the contacts 366 and terminals 365 respectively.

A generally cylindrical rotatable member 330 locates in the housing 310 and has a pair of limbs 331, depending from one end thereof, and which extend to the housing "J" slots 311 to locate on support ledges 317 in the housing 10. The limbs 331 have slots 332 for engagement with the bayonet pins of an inserted bulb. A pair of vertical keyways or channels are also designed internally in the wall of the rotatable member 330.

A shutter member 340 is generally in the form of an inverted dish and locates in the housing 310 within the rotatable member 330. Vertical keys or projections 342 are defined externally on the wall of the shutter 340 to locate in respective keyways 333 in the rotatable member 330 and provide that as the rotatable member 330 is rotated it rotates the shutter 340 with it. The shutter 340 is retained in the housing 310 by means of limbs 347 projecting outwardly of the wall of the shutter. The limbs 347 locate on support ledges 319 defined in the housing wall. A pair of spaced apertures 345 are provided in the base 341 of the shutter 340 and a number of raised ramp formations 344 are defined on and extend from the inner surface of the base 341.

A contact support plate 350 is located in the housing 310, within the shutter 340. The support plate 350 has a pair of spaced apertures 351 through which the end 367 of the contacts 366 protrude. Preferably the contacts 366 prevent the plate 350 rotating relative to the housing 310. A shoulder 370 on each of the contacts 366 engages the support plate 350 so that movement of the plate 350 inwards of the housing moves the contacts 366 inwards of the housing against the force of the bridging springs 364. Thus, the support plate 350 is biased outwards of the housing 310 and against the ramp formations 344 on the shutter 340 by the resiliently loaded contacts 366. Indentations 352 are defined in the support plate 350, on the surface facing the shutter 340.

As the shutter 340 is rotated relative to the plate 350 on bulb insertion, ramp formations 344 on the shutter 340 drop into indentations 352 defined in the surface of the plate 350 facing the shutter 340. Rotation of the shutter 340 relative to the plate 350 also aligns the ends 367 of the contacts with the apertures 345 in the shutter 340 while simultaneously allowing the support plate 350 to be moved outwards of the housing 310. The ends 367 of the contacts 366 are thus lowered through the apertures 345 in the shutter 340 to engage respective pad electrodes of an inserted bulb.

When no bulb is present the lampholder components assume the position illustrated in Figs. 14 and 17. Slots 332 are aligned with the axial portion of the "J" slots 311. The ends 367 of the terminal contacts 366 are located behind the shutter 340. As a bulb is inserted axially into the lampholder the bayonet pins move along the slots 311 and the pad electrodes lOOon the end of the bulb engage the base 341 of the shutter 340 moving the shutter 340 inwards of the housing 310. This also moves the support plate 350 inwards of the housing against the combined force of the resiliently loaded contacts 366. The limbs 342 are raised off the support ledges 319 and clear of the vertical stop faces 316 freeing the shutter 340 to be rotated by the rotatable member 330. The lampholder components thus assume the position illustrated in Fig. 15.

As the rotatable member 330 is rotated by the bulb on bulb insertion it causes the shutter 340 to rotate with it. This moves the formations 344 relative to the support plate 350 until the formations 344 on shutter 340 slide into the indentations 352 defined in the surface of the plate 350. This action also allows the support plate 350 to be moved outwards of the housing 310 as the resilient ends 367 of the contacts are simultaneously ^• aligned with and lowered through the apertures 345 in the shutter 340 to engage their respective pad electrodes 100 of the inserted bulb. At this stage the lampholder components assume the position illustrated in Figs. 16 when the bulb is fully inserted.

As the rotatable member 330 is rotated en bulb removal it rotates the shutter 340 with it, moving the formations 344 relative to the indentations 352. This causes the plate 350 to be moved inwards of the housing 310. As the formations 344 are raised to bear against the surface of the plate 350, simultaneously the ends 367 of the contacts 366 are raised back through the apertures 345 and the apertures 345 become non-aligned with the ends 367 of the contacts 366. As the bulb is removed axially from the lampholder the plate 350 and shutter 340 are moved outwards of the housing 310. The shutter 340 engages the support ledges 319 with the limbs 342 located behind the stop faces 316 to lock the rotatable member 330 against rotation. The lampholder components assume the position illustrated in Figs. 14 and 17.

As illustrated in Fig. 18, the limbs 342 on the shutter 340 may engage ramp faces 318 defined in the housing wall and provide that in the absence of a bulb, if the locking mechanism is overridden by a person using for example, a tool, the interengagement of the limbs 342 and ramps 318 will automatically return the lampholder components to their first "off" position ensuring that the lampholder cannot be left in an unsafe condition.

Fig. 19 illustrates a modified version of the Figs. 14 to 18 embodiment simply incorporating an additional spring 357 which is arranged to act between the terminal block 360 and shutter 340 ( located at peg 349 extending through aperture 354 in support plate 350) to bias the shutter 340 rotationally to its first closed inoperative position.

Turning now to Figs. 20 to 23, they illustrate an alternative embodiment of the present invention incorporating a spring 457 arranged to act between a terminal block 460 and support plate 450, biasing the plate 450 and thereby a shutter 440 outwards of the housing 410 to their first positions. Unlike some of the previous embodiments the contacts 466 are not biasing the plate 450 outwards of the housing to its first position. The shutter 440 abuts against the ends 467 of the loaded terminal contacts depressing them inwards of the housing against the bridging springs 464. The shoulders 470 of the contacts 466 are positioned inwards of the support plate 450 prior to rotation of the shutter 440 and the switching hump formations 444 defined on the shutter 440 are located in "off" indentations 452A defined in the support plate 450. The inner surface of the shutter 440 is substantially flush with the outer surface of the support plate 450.

When no bulb is present, the components assume the position illustrated in Figs. 20 and 23. The cutouts or slots 432 in a rotatable member 430 are aligned with the axial portion of the "J" slots 411 in housing 410 and the contacts 466 are located behind the shutter 440. The apertures 445 in the shutter .440 are also non-aligned with the pair of apertures 451 in the plate 450. The switching hump formations 444 are located in "off" indentations 452A and the shutter 440 and plate 450 are biased outwards of the housing 410 by the spring 457.

As a bulb is inserted axially into the lampholder, the pad electrodes on the end of the bulb 100 move the shutter 440 and thereby the plate 450 inwards of the housing 10, against the force of the spring 457, until the shutter 440 abuts against the ends 467 of the spring loaded contacts 466. When the shutter 440 and plate 450 are moved against the combined forces of the springs 457 and 464 the limbs 442 of shutter 440 are raised off the support ledges 419 and clear of the stop faces 416. The limbs 442 are moved axially within the keyways 433 in the rotatable -ember 430 until the bayonet pins have travelled tc the end of the slots 412. At this stage the rotatable member 430 is unlocked and free to be rotated and the component assume the position illustrated in Fig. 21.

As the rotatable member 430 is rotated by the bulb 100 it rotates the shutter 440 with it, moving the switching humps 444 on the shutter 440 relative to the humps 453 in the plate 450. This causes the shutter 440 to move the plate 450. As the humps 453 ride up on first side of the humps 444, simultaneously the apertures 445 in the shutter 440 are aligned with the ends 467 of the contacts 466. Also, as the humps 453 move down the other side of the humps 444, the shoulders 470 on the contacts 466 engage the plate 450 and plate 450 lowers the contacts 466 such that the ends 467 pass through the apertures 445. Thus, the contacts 466 engage respective pad electrodes of the inserted bulb 100 to make electrical connection between said pad electrodes and the flex terminals 465. At this stage the hump formations 444 on shutter 440 locate in "on" indentations 452B in the plate 450. The surfaces of the plate 450 and shutter 440 lie flush with each other and the lampholder components assume the position illustrated in Fig. 22.

As the rotatable member 430 is rotated on bulb removal it rotates the shutter 440 with it moving the switching humps 444 out of the indentations 452B and back past the humps 453 to relocate in the "off" indentations 452A. This causes the shutter 440 to move tne plate 450 inwards of the housing 410, with the plate 450 raising the contacts 466, via their shoulders 470, inwards of the housing and back through the apertures 445. The apertures 445 become non-aligned with the ends 467 of the contacts, and plate 450 moves the contacts behind the inner surface of the shutter 440. As the humps 444 relocate in the indentations 452A the components assume the position illustrated in Fig. 21.

As the bulb is removed axially from the lampholder the plate 450 and shutter 440 are moved outwards of the housing 410 initially by the combined forces of the resiliently loaded contacts 466 and spring 457 but finally by the springs 457 only, once the shoulder 469 on the contacts 466 is arrested by the ledge 461 in the terminal housing. The lampholder components once again assume their "off" position, in which position the shutter 440 is locking the rotatable member 430 against rotation.

Referring now to Figs. 24 and 25 they illustrate a less elaborate version of the invention similar to the previous embodiment, in which the rotatable member 430' is adapted to shutter the contacts 466. The contacts 466 are resiliently loaded against the inner surface of the rotatable member 430' when no bulb is present. The rotatable member 430 is also prevented from moving axially relative to the housing. A small spring 458 acts between the terminal block 460' and support plate 450' biasing the plate 450' outwards of the housing 410' and against the rotatable member 430' . As with the previous embodiment switching humps 444 ' are provided to interengage humps 453' on the support plate 450' but in this embodiment the humps 444 ' are defined on the rotatable member 430' .

With no bulb present the components assume the position illustrated in Fig. 24. The cutouts or slots 432 of rotatable member 430 are aligned with the axial portions of the "J" slots 411. The contacts 466 are located behind the rotatable member 430, the ends 467 of the contacts 466 being non-aligned with the apertures 445 in the rotatable member 430'. The contacts 466 are also spring loaded against an inner surface of the rotatable member 430'. The limbs 431' of the rotatable member 430' are located on the support ledges 417' in housing 410' and the switching humps 444' are located respectively in "off" indentations 452A' defined in the support plate 450' .

As the bulb is inserted into the lampholder the bayonet pins move along the slots 411 to engage the cutouts 432. Rotation of the bulb causes the rotatable member 430' to rotate with it moving the switching humps 444' in the rotatable member 430' relative to the humps (not illustrated) in the support plate 450'. This action forces the plate 450' inwards of the housing 410' . Also as the humps in the support plate 450' ride over the humps 444^* in the rotatable member 430, simultaneously the apertures 445' in the rotatable member 430 are aligned with the contacts 466. The ends 467 of said contacts 466 are lowered by the plate 450' through the apertures 445' to engage the pad electrodes of the bulb. Prior to the humps 444' locating in "on" indentations in the support plate 450' as the plate 450' was moved outwards of the housing its outer surface lay flush with the inner surface of the rotatable member 430' .

As the rotatable member 430' is rotated on bulb removal the switching humps 444' engage the humps on the support plate 450' moving the support plate 450' inwards of the housing 410'. As the humps on the support plate 450' ride over and past the humps 444' on the rotatable member 430 this causes the plate 450' to move the contacts 466 back through the apertures 445' and inwards of the housing 410' . The contacts 466 are positioned by the plate 450' behind the rotatable member 430' and the switching humps 444' relocate in the "off" indentations 452A so that the lampholder components assume the position illustrated in Fig. 24.

Turning now to Figs. 26 to 28 a shuttered lampholder comprises housing 510 with "J" slots 511 and which is closed by terminal block 560. The terminal block 560 supports flex engaging terminals 565 and has a pair of support limbs 562 to prevent relative rotation of support plate 550.

Rotatable shutter member 530 has apertures 545 and limbs 531 supported on housing ledges 517, and defining axial slots 532 for engagement with the bayonet pins of an inserted bulb. The shutter 530 is rotatable between a closed position in which its apertures 545 are non- aligned with contacts 566 and an open position in which its apertures 545 and contacts 566 are aligned. Upon insertion of a bulb the shutter 530 is moved from a closed to an open position and on removal of a bulb the shutter 530 is moved from its open back to its closed position. A peg 536 is defined centrally on the inner surface of the shutter 530. The shutter is prevented from moving inwards of the housing 510 by the limbs 562 depending from the terminal block 560.

A contact support plate 550 is located in the housing 510, supported within the shutter 530 locating on the peg 536 and is prevented from rotation relative to the housing 510 by the limbs 562 depending from the terminal block 560. A pair of stepped apertures 551 are provided in the support plate 550 to receive bulb engaging contacts 566. As before contacts, 566 are connected via bridging compression springs 564 to flex engaging terminals 565. A central compression spring 558 locates in blind bore 557 in the contact slate 550 and bore 563 ir. the terminal block 560. This biases the plate 550 outwards of the housing 510 and against the inner surface of the shutter 530. Hump formations 553 are defined at the perimeter of the support plate 550 and are arranged to interengage corresponding hump formations 544 at the perimeter of the shutter 530 (see Fig. 28).

The arrangement is such that as the shutter 530 is rotated between its two positions it moves the plate 550 inwards and outwards of the housing 510 as humps 544 are forced past the humps 553. This causes plate 550 to engage the shoulders 570 of the contacts 566 to lower/move said contacts 566 through the respective apertures 545. (The apertures 545 are simultaneously aligned with the apertures 551 and contacts 566 as the shutter 530 is rotated relative to the plate 550. ) The contacts 566 thus engage their respective pad electrodes of the inserted bulb and the shutter 530 assumes its open position. On removal of a bulb the plate 550 engages the contacts 556 moving them back through the apertures 545 and positioning them behind the shutter 530. The apertures 545 in the shutter 530 become non-aligned with the apertures 551 in contact support plate 550 and with the contacts 566 as the shutter assumes its closed position. Thus, the lampholder components assume the position illustrated in Fig. 26.

Thus, when no bulb is present the components assume the position illustrated in Fig.26 the contacts 566 being behind the shutter 530 and apertures 551 and contacts 566 are non-aligned with the apertures 545. The humps 544 in shutter 530 are located in the "off" indentations 552A defined in the support plate 550.

As the bulb is inserted into the lampholder the bayonet pins move along the slots 511 tc engage the cutouts 532. Rotation of the bulb causes the shutter 530 to rotate with it moving the switching humps 544 relative to the humps 553 which action causes plate 550 to be initially moved inwards of the housing 510 to engage the contacts 566 and then move them outwards of the housing 510. The ends 567 of the contacts pass through the aligned apertures 545 to engage their respective pad electrodes of the inserted bulb and the plate 550 is moved outwards of the housing by the force of the spring 558. The apertures 545 and the apertures 551 and contacts 566 are simultaneously aligned as the plate 550 is rotated and moved inwards and.outwards of the housing 510 against the force of the spring 558, as the shutter 530 is moved from its closed to its open position. The hump formations 544 locate in the "on" indentations 552B and the lampholder components assume the "on" position illustrated in Fig. 27.

As the shutter 530 is rotated on bulb removal the humps 544 and 553 engage, causing the plate 550 to engage shoulders 570 of contacts 566 raising them inwards of the housing 510. The ends 567 of said contacts pass back through the apertures 545 to be located against the inner surface 551 of the shutter 530. Simultaneously apertures 545 in the shutter 530 and the apertures 551 in plate 550 and contacts 566 become non-aligned and the shutter 530 resumes its closed position. Thus, the contacts 566 are once again inaccessible and not visible behind the shutter 530 and the lampholder components resume the position illustrated in Fig. 26.

Fig. 29 illustrates a part cross-sectional view of a lampholder of the embodiments of Figs. 26 to 29 modified to incorporate a transverse switchbar 580, which supports a pair of bridging contacts 5S4 which are electrically connected via bridging springs 564 to the bulb engaging contacts 566. The switchbar 580 is movable transversely between an "off" position, as illustrated, in which there is no connection between the bridging contacts 584 and the terminals 565 in the terminal block 560, and an "on" position, in which bridging contacts 584 engage terminals 565 to make an electrical connection. The spring 558' is arranged to act between the switchbar 580 and support plate 550 biasing the support plate 550 outwards of the housing 510 against the shutter 530.

Figs. 30 and 31 show a further embodiment which includes a housing 610 having "J" slots 611 and closed by terminal block 660 supporting terminals 665. Located in the housing 610 is a bridge support member 620 which is provided with a pair of spaced apertures 621 and a pair of arcuate slots 622 adjacent the housing wall. An upstanding peg 623 is also defined centrally on the inner surface of said bridge 620 and hump formations 644 are defined internally on the bridge and adjacent the housing wall 610. Support ledges 617 and 619 are also defined internally in the housing wall.

A cylindrical rotatable member 630 locates in the housing 610 and has limbs 631 which extend through arcuate slots 622 in bridge 620 to the housing "J" slots 611. The limbs 631 are supported on ledges 617, and define slots 632 for engagement with the bayonet pins of an inserted bulb. Slots 611 and 632 are arranged such that rotation of a bulb causes the rotatable member 630 to rotate with it. The rotatable member 630 is prevented from moving axially relative to the housing by the terminal block 660.

A contact support plate 650 is located between terminal block 660 and bridge 620 and within cutouts 635 in the rotatable member 630, locating or. peg 623 on bridge 620. The contact plate 650 can move axially within the cutouts 635. As the rotatable member 630 is moved by a oulb from a first to a second position it rotates/drives the contact plate 650 from a closed to an open position, in which the pairs of apertures 621 and 651 in the bridge 620 and plate 650 respectively are aligned. As the rotatable member is moved by the bulb from its second back to its first position it rotates/drives the contact plate 650 from its open back to its closed position in which the pairs of apertures 621 and 650 are non-aligned.

Stepped apertures 651 provided in support plate 650 are arranged to receive bulb engaging contacts 666. A compression spring 658 acts to bias the support plate 650 outwards of the housing 610 against the bridge 620, one end of the spring locating in the bore 657 in the plate 650 and the other end locating in bore 663 in terminal block 660.

Hump formations 653 are defined on the perimeter of the support plate 650 to interengage corresponding hump formations 644 on bridge 620 and provide that, as the plate 650 is rotated between its two positions it is moved inwards and outwards of the housing 610. As the humps 653 ride over the humps 644 the plate 650 engages the contacts 666 lowering them through the aligned apertures 621 to engage the pad electrodes of an inserted bulb. As the plate 650 is moved by the rotatable member 630 from its open back to its closed position it engages the contacts 666 raising them back through apertures 621 and behind the bridge 620 and the two pairs of apertures 621 and 651 become non-aligned.

It will thus be appreciated that when no bulb is present the components assume the position illustrated in Fig. 30 witr. the contacts 666 located behind bridge 620 and the ends 667 of contacts 666 and the apertures 651 non-aligned with the apertures 621.

As a oulb is inserted into the lampholder the bayonet pins move along the slot 611 to engage the cutouts 632. Rotation of the bulb causes the rotatable member 630 to rotate with it thereby rotating the support plate 650 and the humps 653 relative to the humps 644 on the bridge 620. This causes plate 650 to be initially moved inwards of the housing 610 to engage and move contacts 666 outwards of the housing 610 and through the apertures 621 to engage pad electrodes of the inserted bulb. Plate 650 is moved outwards of the housing 610 by the force of the springs 658. The lampholder components assume the "on" position illustrated in Fig. 31, with the hump formations 644 locating in the "on" indentations 652A.

As the rotatable member 630 is rotated on bulb removal, the hump formations 653 and 644 provide that the plate 650 engages shoulders 670 and raises the contacts 666 inwards of the housing 610, the ends 667 of said contacts 666 passing back through the apertures 621 to locate on the inner surface of the bridge 620. Simultaneously the two pairs of apertures 621 and 651 become non-aligned and plate 650 resumes its closed position in which it shutters apertures 621. Contacts 666 are once again inaccessible and not visible behind the bridge 620. The lampholder components again assume the position illustrated in Fig. 30.

Turning now to Figs. 32 to 47 they show cross- sectional views of an assembled lampholder according to another embodiment, and views of the various lampholder components. When the lampholder is assembled and no bulb present the components assume the position illustrated in Fig. 32. (For features of this embodiment which are similar to the previous embodiment, comparable reference numerals are employed advanced by 100) . The cutouts 737, which may be straight or angled as illustrated are aligned with the axial portion 712 of the "J" slots 711. The contacts 766 are located behind the bridge 720 and spring loaded against the inner surface of the bridge in the cupped recesses "A". Apertures 721 in the bridge are closed off by the rotatable shutter 730. Small peg-like formations "B" on the base of the shutter 730 extend into the apertures 721 and act to.shield the ends 767 of the contacts 766 when in their cupped recess. (This allows for a minimum amount of material beneath the contacts 767 thereby reducing the distance the contacts are required to be moved outwards of the housing to engage the pad electrodes 100). The shoulder 770 of the contacts 766 are raised clear of the steps 756 in the shutter 730 the limbs 731 of shutter 730 are located on the ledges 717 humps 753 on the rotatable member are located on the "off" side of humps 744 defined in the housing wall.

As a bulb is inserted into the lampholder the bayonet pins move along the slots 711 to engage the cutouts 732. Rotation of the bulb causes the shutter 730 to rotate with it and humps 753 ride up the "off" side of the humps 744 in the housing. This causes the shutter 730 to be simultaneously moved inwards of the housing and rotated. Steps 756 engage the shoulders 70 of the contacts 766, prior to the hums 753 reaching the apex of the humps 744. When humps 753 move down the "on" side of the humps 744 (while simultaneously the contacts 766 are becoming aligned with the apertures 721 in the bridge 720) causing the shutter to move outwards of the housing 710 by the force of the springs 764 and 758. The ends 767 of the contacts 766 extend through the now aligned apertures 721 to engage the pad electrodes of the inserted bulb and the components assume the position illustrated in Fig. 33 with the shutter in its open position. On bulb removal the above procedure is reversed, the steps 756 engage the shoulders to raise the contacts and lowering them back behind the bridge into the cupped recesses "A" where they are shuttered. Figs. 34 and 35 are cross-sectional views of the housing 710 of this embodiment illustrating in more details the hump formations 744 and features of the bridge 720. Figs. 36 and 37 are plan views of the housing 710 and bridge 720. Figs. 38 to 43 are cross-sectional views of the rotatable member 730 of this embodiment, illustrating in more detail hump formations 753. Figs. 44 to 47 illustrate the features of the terminal block 760.

Figs. 48 to 53 illustrate a further embodiment of the invention. Fig. 48 illustrates a shuttered lampholder comprising housing 810 having slots 811. The housing 810 is closed by terminal block 860 which supports resilient flex engaging terminals 865. A bore 863 in the terminal block 860 receives one end of compression spring 858.

A shutter 820 locates in the housing 310 and has a peripheral wall 821 which extends to the housing "J" slots 811 and defines slots 822 for engagement with the bayonet pins of a bulb. Slots 811, 822 are arranged such that insertion of a bulb causes the shutter 820 to be moved axially inwards of the housing 810 and to rotate with it from its closed to its open positior.. Removal of a bulb causes the shutter 820 to rotate and move axially outwards of the housing 810 to its closed position. A pair of spaced elongated apertures 823 are provided in the surface of the shutter 820. Hump formations 824 are also defined on the perimeter of the inner surface of the shutter 82C. together with a central location peg 825 for engaging an axially movable member 830.

The axially movable member 830 is located in the housing 810 and is provided with a pair of spaced, stepped contact receiving apertures 831 and a raised boss 834 on its inner surface which provides a spring housing 832 to receive one end of a compression spring 858. A central bore 833 is also provided in the outwardly directed face of the member 830 and receives peg 825 on shutter 820. Hump formations 834 are provided at each end of the member 830. The formations 834 are arranged to interengage hump formations 824 on the shutter 820 and provide that, as the shutter 820 is rotated on bulb insertion, it moves the axially moveable member 830 inwards and outwards of the housing 810 as the humps 834 ride over the humps 824. Bulb engaging contacts 840 in the form of metal cylinders and provided with shoulders 841 locate in the apertures 831 in the axially moveable member 830. The contacts 840 in their first position bear against the inner surface of the shutter 820. Bridging springs 850 are arranged between the terminals 865 and contacts 840.

When no bulb is present the lampholder components assume the position illustrated in Fig. 48. Slots 822 are aligned with the axial portion 812 of the "J" slots 811 and contacts 840 are located behind shutter 820 and are spring loaded against it. The apertures 823 in the shutter 820 are closed by formations 836 and 837. The shutter 820 is spring biased against support ledge 817 and hump formations 824 on the shutter 820 are located on the "off" side of the hump formations 834 en the axially moveable member 830.

As a bulb is inserted axially into tne lampholder the bayonet pins move into the aligned slots 812 and 822 and the pad electrodes of the bulb abut against the outer surface of the shutter 820, causing the shutter 820 and member 830 to be moved inwards of the housing 810 against the combined forces of the springs 850 and 858 and the lampholder components to assume the position best illustrated in Figs. 49 and 52 after this axial stage of bulb insertion. Rotation of the bulb causes the shutter 820 to rotate with it and the humps 834 to ride up the humps 824 to move member 830 axially inwards of the housing 810. Steps 835 on member 830 engage shoulders 841 of the contacts 840, raising the contacts 840 off the surface of the shutter 820. Prior to the humps 834 reaching the apex of the humps 824 the lampholder components assume the position illustrated in Figs. 50 and 53 after partial rotation of the bulb.

On continued rotation of the bulb the humps 834 move down the "on" side of the humps 824 causing the axially movable member 830 to be moved outwards of the housing 810 by the combined forces of the springs 850 and 858 and to lower the ends 842 of the contacts 840 through the aligned, elongated apertures 823 in the shutter 820 to engage the pad electrodes of the inserted bulb. The spring 858 moves the member 830 further outwards of the housing to engage the inner surface of the shutter 820 and the lampholder components assume the "on" position illustrated in Fig. 51. The shutter 820 is in its open position and hump formations 834 are located on the "on" side of the humps 824 respectively.

As the shutter 820 is rotated on bulb removal the bayonet pins move along the horizontal portions 813 of the "J" slots 811 causing the humps 834 to ride up the "on" side of the humps 824 and the axially moveable member 830 to be initially moved inwards cf the housing 810, the steps 835 engaging the shoulders 841 of the contacts 840. This moves contacts 840 inwards of the housing 810 against the force of the springs 850, the ends 842 of the contacts 840 passing back through the apertures 823 to be relocated against the inner surface of the shutter 820. The humps 834 move down the "off" side of the humps 824 and the formations 836 and 837 close off the apertures 823 in the shutter 820, and the member 830 abuts against the inner surface of the shutter 820. As the bulb is removed axially from the lampholder the springs 858 and the springs 850 cause the shutter 820 and member 830 to be moved outwards of the housing 810 to the first positions, the shutter 820 relocating on the support ledge 817 and the components assuming the position illustrated in Fig. 48, in which position the terminal contacts are inaccessible and not visible behind the shutter.

Referring now to Figs. 54 to 57 there is shown an alternative arrangement in which the shutter 920 moves axially only, and a member 930 moves axially and is rotatably driven by the bulb. Hump formations 934 on the member 930 ride over humps 924 on the shutter 920 as the member 930 is rotated in order to raise and lower the contacts 940 through elongated apertures 923. The shutter 920 and member 930 are both moved inwards of the housing 910 by the pad electrodes on axial bulb insertion and the member 930 closes the apertures 923 in the shutter 920 when no bulb is present.

When no bulb is present the components assume the position illustrated in Fig. 54 with slots 932 aligned with the axial portion 912 of the "J" slots 911 and contacts 940 located behind shutter 920. The ends 942 of contacts 940 are spring loaded against shutter 920 and apertures 931A in the member 930 are non-aligned apertures 923 in shutter 920. The shoulders 941 of the contacts 940 are raised clear of steps 935 in the member 930. The member 930 is spring biased outwards of the housing 910 and against the shutter 920 and the hump formations 934 are located respectively on the "off" side of the humps 942 on the shutter 920.

As a bulb is inserted axially into the lampholder the bayonet pins move into the aligned slots 912 and 932 and the pad electrodes 100 of the bulb engage the outer surface of the shutter 920 causing the shutter 920 and member 930 to be moved inwards of the housing 910 against the combined forces of the springs 950 and 958 and the lampholder components assume the position illustrated in Fig. 55 after this axial stage of bulb insertion. Rotation of the bulb causes the member 930 to rotate with it and the humps 934 on the member 930 to ride up the humps 924 on the shutter 920. This causes the member 930 to move axially inwards of the housing 910 as it is also being rotated. The steps 935 engage shoulders 941 of the contacts 940, raising the contacts 940 off the surface of the shutter 920 prior to humps 934 reaching the apex of respective humps 924. After this partial rotation step the components assume the position illustrated in Fig. 56. On continued rotation of the bulb humps 934 move down the "on" side of the humps 924, causing the member 930 to be moved outwards of the housing 910 by the forces of springs 950 and 958 as it is simultaneously being rotated by the bulb, and shoulders 935 lower contacts 940 such that the ends 942 pass through the aligned apertures 923 and 931A in the shutter 920 and member 930 respectively. The contacts 940 engage their respective pad electrodes of the inserted bulb, the pad electrodes arresting outward movement of the contacts 940 and the spring 958 moving the member 930 to engage the inner surface of the shutter 920. At this stage the shutter 920 is in its open position, with humps 934 located on the "on" side of humps 924 and the lampholder in the "on" position. This is illustrated in Fig. 57.

On bulb removal the above procedure is reversed, the member 930 is rotated to raise contacts 940 and locate them back behind the inner surface of the shutter 920, the apertures 923 in the shutter are closed by the member 930 and formations 937, and the shutter 920 and member 930 are moved outwards of the housing 910 to their first position, in which the shutter 920 relocates on the support ledge 917 and the components assume the position shown in Fig. 54, in which the live terminal contacts are inaccessible and not visible behind the shutter 920.

Formations defined between the housing 910 and shutter 920 which are not shown prevent the shutter rotating relative to said housing 910.

Claims

1. A safer-/ lampholder for a bayonet bulb comprising a hollow housing defining slots at one end thereof to receive bayonet pins of an inserted bulb, bulb engaging contacts within the housing for electrical connection to a power source to supply electricity to the bulb, apertured εnutter means located within the housing for selectively obstructing access to the contacts and arranged such that insertion and removal of a bulb actuates relative movement of the contacts and shutter means between a first inoperative position in which the contacts are obstructed by the shutter means and a second operative position in which the contacts extend through the apertures in the shutter means to bear against an inserted bulb, interengageable surface formations being provided within the housing for actuating displacement of the contacts and arranged such that, upon rotation of an inserted bulb, the contacts are displaced inwardly of the housing from their first position and then outwardly of the housing through apertures in the shutter means into their second position, and upon removal of a bulb the contacts are displaced inwardly of the housing through the apertures in the shutter means and outwardly of the housing to return to their first position.

2. A safety lampholder according to Claim 1 wherein power supply terminals are supported in the housing and the bulb engaging contacts are electrically connected to the power supply terminals by flexible conducting elements.

3. A safety lampholder according to Claim 2 wherein the bulb engaging contacts are biased outwardly of the housing by the flexible conducting elements.

4. A safety lampholder according to any preceding claim wherein the bulb engaging contacts are located in an axially moveable contact carrier capable of actuating displacement of the contacts between their first and second positions.

5. A safety lampholder according to Claim 4 wherein the contact carrier engages the contacts to actuate displacement thereof upon rotation of an inserted bulb.

6. A safety lampholder according to Claim 4 or 5 wherein the contact carrier is biased outwardly of the housing.

7. A safety lampholder according to any preceding claim wherein a rotatable member is mounted in the housing and extends to the housing slots and defines slots for engagement with the pins of an inserted bulb, the housing slots and rotatable member slots being arranged such that insertion of a bulb causes the rotatable member to rotate from a first to a second position and removal of the bulb causes the rotatable member to rotate from the second to the first position.

8. A safety lampholder according to Claim 7 wherein an axially movable contact carrier is located in the housing and surface formations are provided on the contact carrier and arranged to interengage with surface formations on the rotatable member such that rotation of the rotatable member drives axial displacement of the contact carrier and displaces the contacts between their first and second positions.

9. A safety lampholder according to Claim 7 or 8 wherein the rotatable member is apertured and provides a shutter means.

10. A safety lampholder according to Claim 7 or 8 wherein rotation of the rotatable member actuates rotation of a shutter means.

11. A safety lampholder according to any preceding claims wherein the shutter means are axially movable.

12. A safety lampholder according to claims 10 and 11 wherein the shutter means are axially movable between first and second positions and which provide locking means such that when the shutter means are in their first position movement of the rotatable member is obstructed and when the shutter means are in their second position movement of the rotatable member is permitted.

13. A safety lampholder according to claim 11 or 12 wherein the shutter means are biased outwardly of the housing.

14. A safety lampholder according to any preceding claim wherein the bulb engaging contacts are accommodated in recesses in the shutter means when in their first position.

15. A safety lampholder^' according to Claim 14 wherein the recesses are alongside the apertures in the shutter means.

16. A safety lampholder according to Claim 14 or 15 wherein means are provided for shielding the contacts from the apertures when the contacts are located in recesses in the shutter means.

17. A safety lampholder according to Claim 14 wherein the shielding means comprise surface formations depending from a contact carrier.

18. A safety lampholder according to Claim 8 wherein the housing includes a bridge member having arcuate slots which accommodate limbs of a rotatable member to permit rotation thereof between first and second positions, the bridge member also having a pair of apertures to permit passage of bulb engaging contacts therethrough to bear against an inserted bulb.

19. A safety lampholder according to Claim 18 wherein surface formations are provided on the housing to drive axial displacement of the contacts between their first and second positions.

20. A safety lampholder according to Claim 19 wherein the contacts are rotatable with respect to the bridge member by the rotatable member and the bridge member provides a shutter means.

21. A safety lampholder according to any preceding Claim wherein the interengagable surface formations comprise opposing hump formations.

22. A safety lampholder according to any preceding claim wherein the surface formations are provided at or near the internal peripheral wall of the housing.

23. A safety lampholder according to Claims 21 or 22 wherein a hump formation comprises a first ramp face and a second ramp face of a length different to that of the first ramp face.

24. A safety lampholder according to any preceding claim wherein surface formations are circumferentially spaced within the housing.