AU671021B2 - Safety lampholder - Google Patents

Description

4 2267607 1 SAFETY LAMPHOLDER 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. In one type of safety lampholder, described in DE 2651334, a shutter mechanism is used to place a shutter between a socket defined by the lampholder to receive 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. Accordingly, in one aspect the present invention provides a safety lampholder for

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JSS290493 a bayonet bulb comprising a body defining slots to receive bayonet pins of an inserted bulb, contacts within the body for electrical connection to a power source to supply electricity to the bulb, rotatable apertured shutter means in the body for selectively obstructing access to the contacts and arranged so as to be actuable upon rotation of the bulb and surface formations within the body capable of actuating axial displacement of the contacts relative to the shutter means and upon rotation of the hiutter means, between a first S inoperative position which the contacts are located behind the rotatable shutter means and a second operative position in which they extend through apertures in the shutter means for bearing against a bulb.

Such an arrangement is particularly advantageous in that it provides an effective means for bringing the contacts into engagement with an inserted bulb and for driving the contacts back into an obstructed position. Rotation of the shutter means is appropriately actuable, directly or indirectly, by rotation of the inserted bulb. The shutter means or other S. part of the lampholder has surface formations, conveniently of ramp form, to directly or indirectly cause the contacts to reciprocate so that they can move up and down or backwards and forwards in a reversible fashion so as to be either obstructed by the shutter means or extending therethrough. The arrangement is generally such that rotation of the bulb effectively actuates rotation of the shutter and axial movement of the contacts.

Preferably the shutter means is provided with formations which interengage directly or indirectly with the contacts in the lampholder. In this way, the arrangement is suitably such that rotational movement imparted to the shutter means on bulb insertion and removal is converted into linear or axial movement of the bulb engaging contacts in the lampholder.

In preferred embodiments the surface formations are at or I c I JSS290493 3 near the internal periphery of the lampholder, conveniently associated with the body or the rotatable shutter means.

Suitably the surface formations are spaced from apertures in the shutter means.

To improve safety, it is preferred that means are provided for shielding apertures in the shutter means when the contacts are in the inoperative position. Preferably the shielding means are actuable upon rotation of an inserted bulb. In preferred embodiments the shielding means are provided by limbs depending or extending from the housing or from a terminal block, for example.

To assist location of the terminals/contacts in the apertured shutter means, preferably means are provided for resisting angular or rotation movement of the terminals/ contacts.

According to preferred embodiments of the present invention there is provided a lampholder for receiving a bayonet bulb, comprising a body defining slots along which bayonet pins of an inserted bulb slide, resilient flex S engaging terminals (or contacts) supported by the body adapted to be electrically connected to a power supply and to electrically engage the pad contacts of an inserted bulb, a shutter mounted in the body and rotatable by engagement with an inserted bulb between a closed position when the bulb is removed, in which position the shutter obstructs access to the flex terminals and an open position when the bulb is fully inserted, in which position the flex terminals extend through apertures which are formed in the shutter to bear against the pad contacts of the inserted bulb.

The invention is preferably characterised in that the inner surface of the shutter, the surface remote from the inserted bulb, defines ramps which directly or indirectly are engaged by resilient flex terminals mounted in the body to JSS290493 4 provide a connection between an electrical supply and a light bulb, such that, rotation of the said shutter relative to lampholder body by the insertion of a bulb causes the said flex terminals to move outward of the lampholder, towards the bulb, as they are directly or indirectly lowered down said ramp surfaces such that they extend through apertures which are formed in the shutter, to bear against their respective pad contacts of an inserted bulb. As the shutter is rotated on removal of a bulb said ramp surfaces act to raise directly or indirectly the flex terminals inward of the lampholder and back through the apertures in the shutter. Formations extending from the body may close off said apertures in the shutter as the bulb is removed and open said apertures as a bulb is inserted.

In preferred embodiments the bulb engaging ends of the flex terminals are mounted in an axially movable carrier member which is slidably mounted in the body and is conveniently spring biased outward of the lampholder by the flex terminals. The other ends of the terminals, which engage the power supply cable, are fixed relative to the body with the carrier member being interposed between the body (or terminal block) and shutter. Bearing surfaces are suitably defined on the said carrier member which engage the ramp surfaces defined on the shutter such that insertion of a bulb causes the carrier member to be moved axially outward to the lampholder and thereby the flex terminals to engage the pad contacts of the bulb, and removal of the bulb causes the carrier member to be moved axially inward of the lampholder thereby raising the flex terminals back behind the shutter.

Preferably, resting slots are provided at the top of each ramp member on the shutter in which the bearing surfaces defined on the said carrier member locate when the lampholder is in the first inoperative position, said resting slots providing resistance to movement of the shutter to the second operative position.

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JSS290493 The resilient flex terminals may be of a conventional nature, consisting of three separate components, a screw terminal, compression spring and pin contact. However, a flex terminal of the screwless type may be provided in the form of a single strip of conductive spring metal, of any desired section i.e. flat or round etc,. coiled to give the desired resilience, the terminal end of said strip secured in the body and fashioned to resiliently grip the electrical power cable in known manner. The other end of said terminal is attached to the axially movable carrier member which is slidably mounted in the body, the said flex terminal acting to bias the carrier member outward of the lampholder body as previously mentioned, ramp surfaces on the shutter interengage with bearing surfaces on the said carrier member so as to raise and lower the end of the flex terminal through the apertures in the shutter as bulb is inserted and removed from the lampholder.

Preferably, at least one locking member is supported by the body, the or each locking member being biased towards a locked position in which it prevents movement of the shutter from the first off position to the second on position, and the or each locking member being arranged such that it is engaged by an inserted bulb so as to be moved by the inserted bulb to an unlocked position in which the shutter is free to move from the first 'off' position to the second 'on' position.

In such preferred embodiments, the or each locking member is suitably engaged by an inserted bulb so as to be moved to the unlocked position as the bulb is initially inserted into the lampholder before rotation of the bulb to fully engage the bulb bayonet pins with the lampholder. As the bulb is subsequently rotated its bayonet pins directly bear against the shutter so that the shutter rotates with the bulb.

If desired, the or each locking member may extend ~cg~ I JSS290493 adjacent the side wall of a bulb receiving socket defined by the lampholder body so as to be engaged by a peripheral portion of the bulb. Alternatively the or each locking member may be arranged to be directly engaged by a respective bayonet pin of the inserted bulb.

The locking member when in the locked position may be arranged in slots defined in the lampholder body and the shutter, the locking member being lifted out of one of the slots to enable rotation of the shutter when a bulb is inserted.

Alternatively, or in addition thereto, a central locking member may be provided preferably circular in section, and extending between the shutter and terminal block and biased to the locked position by a compression spring. Projections on the locking member engage in axial slots within sockets defined by the shutter and terminal block and prevent relative rotation between the locking member and the shutter. As a bulb is inserted it pushes the locking member inward of the lampholder lifting the said projections out of engagement with the shutter which can then rotate relative to the terminal block and lampholder body.

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 first embodiment of the present invention; Figs. 2a and 2b illustrate a modification to the Fig. 1 embodiment; Figs. 3a, 3b and 3c illustrate another embodiment of the present invention; JSS290493 7 Fig. 4a is an exploded view of a further embodiment of the present invention; Fig. 4b is a plan view of a housing of Fig. 4a; Figs. 4c, 4d and 4e are cross-sectional views of an assembled holder of Fig. 4a; Fig. 4f is a plan view of the housing of Fig. 4b with the shutter assembled; 9 Fig. 4g is a plan view of the assembly of Fig. 4h with the contact plate and bulb engaging contacts assembled; Fig. 4i is a cross-sectional view of a lampholder according to Fig. 4 converted to a non-switching lampholder; Fig. 5a is a part cross-sectional view of the housing of an alternative embodiment and Figs. 5b and 5c show parts for use with this housing; Fig. 6 is an exploded view of a lampholder according to a further alternative embodiment of the present invention; Fig. 6a is a plan view of a housing of housing of the Fig. 6 embodiment; Figs. 6b and 6c are cross-sectional views of an assembled lampholder of Fig. 6; Figs. 6d and 6e are enlarged, part cross-sectional views of the Fig. 6 lampholder; Figs. 7a, b and c, are enlarged, part cross-sectional views of another alternative contact/terminal assembly; Figs. 8a and 8b are cross-sectional views of an assembled JSS290493 8 lampholder of Fig. 6 incorporating an alternative contact/terminal assembly; Figs. 9a and 9b are cross-sectional views of an assembled lampholder of an alternative embodiment; Figs. 9c and 9d are views of the rotatable member of the embodiment of Figs. 9a and 9b; Figs. lOa and 10b are cross-sectional views of an assembled lampholder according to a further alternative :i embodiment of the present invention; Fig. 10c is a cross-sectional view of the shutter of and Fig. 10d is perspective view of the axially movable member of Figs. 10a and Fig. 1Oe is a cross-sectional view of a sub-assembly of a terminal block, axially movable member and terminal/contact of the embodiment of Fig. 10a and 10b; and Figs. lla and llb are cross-sectional views of yet another alternative lampholder according to an embodiment of the present invention.

Referring now to Fig. 1 the illustrated lampholder comprises a body 10 in which a terminal block 30 is a snap engaging fit. The terminal block 30 supports a pair of flex terminals 67 which, in use, are connected to conductors of an electrical flex. A lampholder cap (not illustrated) is in use fitted onto the top of the lampholder body 10 so as to cover the terminals 67 whilst providing an entry port for the power supply flex. Locations 16 on the body 10 are to accept the clips of a clip on type cover.

The terminal block 30 also supports a terminal pin I-

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JSS290493 carrier 50 which is slidably mounted in the housing 31. The pin carrier 50 is provided with apertures 51 to receive pin terminals 60 which are retained therein by means of the annular shoulders 61, with coil springs 66 locating on the pin terminal. Flex terminals 67 are engaged in the terminal block in locations 33 such that they bridge the housing 31 and thereby retain the carrier member 50 in the terminal block Once assembled the compression springs 66 act to bias the carrier member 50 inward of the terminal block 30 and also provide a resilient electrical bridging connection between the flex terminals 67 and pin terminals 60. The carrier 50 may be moved axially within the terminal block housing 31 between a first and second position.

A shutter means 20 is located in the body 10 by the terminal block 30 and is rotatable relative to the body 10 and terminal block 30. Raised ramps 23 defined by the shutter on the surface 27 facing the terminal block 30 engage bearing surfaces 52 of the carrier 50. In use the arrangement is such that rotation of the shutter 20, on insertion of a bulb, provides that the said bearing surfaces 52 are depressed inwardly in of the lampholder and thereby raised out of the oe.o.i holding recesses 25. The bearing surfaces 52 then follow the ramp surfaces 24 outward of the lampholder. This action moves the pin terminals 60 outward of the lampholder to extend through the apertures 26 in the shutter 20 to bear against their respective pad contacts 77 of the inserted bulb.

As the shutter 20 is rotated during removal of a bulb, the ramp surfaces 24 act to raise the pin carrier 50, and thereby the pin terminals 60, inward of the lampholder and back through the apertures 26 in the shutter 20. The bearing surfaces 52 thus locate in the holding recesses 25 in the first inoperative position. Formations 34 extending from the terminal block 30 effectively close off the apertures 26 in the shutter 20 in the first inoperative position. Faces 36 and 37 on the block 30 act as guides and supports for the pin JSS290493 terminals 60 and retain the pin carrier 50 assembly in the terminal block 40. Numeral 38 denotes the shut off faces.

As in conventional lampholders, the body 10 defines slots 11 into which the pins of a bayonet type bulb are inserted.

When the shutter 20 is in the first inoperative position recesses 22 defined by the shutter 20 are in alignment with the slot 11. Accordingly, as the bulb is inserted, the bayonet pins move along the slot 11 and into the recesses 22, so that rotation of the bulb causes the shutter 20 to rotate with it until the bulb bayonet pins drop into the recesses 13 which are defined in the body 10 and communicate with the entry slots 11. The bulb is then held securely in the lampholder and can only be removed by reversing the above procedures so that the bayonet pins move back to the slots 11 driving with them the shutter When the bulb is initially inserted, the pin carrier is in a raised inoperative position with its bearing surfaces 52 located in the holding recesses 25. The apertures 26 in the shutter 20 are closed off by means of the shut off faces 38. The live pin terminals 60 are on the side of the shutter .:.ooi S" remote from the inserted bulb. As the shutter 20 is rotated the bearing surfaces 52 are raised out of their respective holding recesses 25 by the ramp members 23 which depress the pin carrier inward of the lampholder against the force of the springs 66. Continued rotation of the shutter 20 causes the bearing surfaces 52 to slide down their respective ramp faces 24. Simultaneously apertures 26 are being opened in the shutter 20 as it moves relative to the shut off faces 38.

Thus the pin terminals on the carrier member 50 are moved outward of the lampholder such that they extend through the apertures 26 in the shutter to bear against their respective pad contacts of the inserted bulb. When the bulb is subsequently removed, the lampholder components return to a position in which the live terminal pins 60 are inaccessible even if a finger or wire is inserted into the end of the

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JSS290493 lampholder into which a bulb is normally inserted and furthermore no visible bulb engaging contacts would indicate to a user that the lampholder as proposed was safe.

Referring now to Figs. 2a and 2b, these show a slightly modified lampholder of Fig. 1 in which the terminal block and shutter 20 have been adapted for use in a metal body shell. 7n this example, the terminal block 40 is retained in a body 71 and prevented from rotation therein by means of the .:.ooi S finger members 75 which are bent over to engage in the recesses 79 in the terminal block 50. The cover 75 and body 71 are secured together in a conventional manner by means of the threaded locking ring 73. Fig. 2b illustrates a modified body 71 the end of which has been bent over to provide a lip 76 the associated shutter 20 having an extended side 21 so as to locate on the said lip 76 and an elongated aperture 22.

The operation of this modified version is identical to that of Fig. i.

Referring now to Figs. 3a, 3b and 3c a second embodiment of the present invention is shown. The principle of operation is the same as that of Fig. i. According to this embodiment the bulb engaging terminal assembly is mounted in the terminal block 30 and provides a resilient connection between an electrical supply and the pad contacts 77 of a light bulb.

Fig. 3c illustrates a partly exploded view of a terminal assembly and shows how a blade member 62 is inserted into an aperture 53 in an assembled terminal block 40. Sides of the blade member 62 locate in elongate slots 54 to be slidably mounted therein. A compression spring 66 is then assembled into a bore 55 and locates in the blade member 62 on the location 69. A flex terminal 67 is then assembled in apertures 33 to as to bridge the aperture 53 and thereby retain the resilient terminal assembly in the terminal block The terminal blade 62 protrudes from the terminal block with limbs 68 on the terminal blade 62 engaging shoulders 42 on the terminal block 40 thereby restricting movement of Ib IPII1I~I~-~SP_-I ~111 11 r I JSS290493 spring biased blade 62 relative to the lampholder body.

The body 10 and the shutter 20 are identical to that of Fig. 1, in that the shutter supports ramps 23, apertures 26 and holding recesses 25. However, in this embodiment, the terminal 62 bears directly against the ramp surfaces 24 and The bent over section 64 of the terminal blade 62 provides, the bearing surface and the finger 65 extends through the shutter to engage the contact pads 77 of an inserted bulb.

Fig. 3a illustrates the lampholder in its first inoperative position, which it assumes when no bulb is present. As a bulb is inserted and the shutter 20 is rotated, the bearing surfaces 64 are raised out of their respective holding recesses 25 by the ramps members 23. The ramp members 23 depress the terminal blades 62 vertically inwardly of the lampholder against the force of the springs 66, and the bearing surfaces 64 are spring biased outward of the lampholder 10. The bearing surfaces 64 thus slide down the ramp faces 24 as the shutter 20 is rotated. Simultaneously apertures 26 are opened in the shutter 20 to permit fingers t, to extend through apertures 26 in the shutter to bear agains their respective pad contacts 77 of the inserted bulb as illustrated in Fig. 3b. On removal of a bulb the lampholder components will resume the position shown in Fig. 3b.

The recesses 22 in the shutter 20 may be angled as illustrated in Fig. 3c such angled recesses 22a will allow increased shutter rotation, as a bulb would rotate the shutter as it was being moved vertically in the slot 11 as well as when it was being moved horizontally in the slot 11.

Referring now to Figs. 4a to 4h, there is illustrated a switched shuttered lampholder comprising a hollow cylindrical housing 110 into one end of which can be received the cap of a bayonet type bulb. As before, the housing 110 is provided ~e~sp~eR~i~wps~pr~ I JSS290493 13 with conventional slots 11 to receive the bayonet pins respectively of a bulb. (The slots 111 comprise an axial portion 112 and a circumferential portion 113 which is provided with the usual resting point to retain the bulb in position.) The housing 110 is also provided with a plain band 114 intermediate its ends below which is a screw thread intended to retain a shade locking ring. The plain band 114 defines cut-outs 116 to accept clips of a clip-on type cover (not illustrated). In use the cover is fitted into the top of the lampholder housing 110 so as to cover the terminals 171 whilst providing an entry port for the power supply flex. The housing 110 also defines a pair of diametrically disposed cutouts 120 which are positioned generally at right angles to the bulb resting points 113 in the slots 11.

n Also located in the housing 110 is a bridge support member 121 which is provided with a pair of apertures 23 and a r.r pair of arcuate slots 122 adjacent the housing wall. An upstanding peg 128 is defined centrally on the inner surface of said bridge member 121. Support ledges 117 and 127 are defined internally in the housing 110, also vertical flat o* faces 118. The other end of the housing is closed by a terminal block 170 which is disc shaped and provided with two flat faces 173. On assembly the flat faces 173 engage the flat faces 118 defined in the housing 110 preventing relative rotation.

The terminal block 170 supports a pair of flex engaging terminals 171, which extend through the terminal block so as to be exposed on opposite sides thereof. Limbs 175 are defined on and depending from the surface of the terminal block facing the bridge member 121 said limbs 175 preventing the contact plate 140 and contact carrier 151 rotating relative to the housing 110.

JSS290493 14 A shutter member 130 in the form of a disc is provided and defines a pair of limbs 131 depending therefrom. The limbs 131 are provided with cut-outs 132 to receive the bayonet pins of a bulb. Ramp/cam surfaces 136 are also defined on the periphery of and extend from the surface of the shutter facing the terminal blcck 170. Indents or holding recesses 138 are provided at the top of each ramp/cam surface 136. A central aperture 135 is provided on the shutter to engage the peg 128 on the bridge member 121 providing location and centralising means for the shutter 130 in the housing 110.

A pair of spaced apertures 134 are also provided on the shutter. In the operative position of the lampholder the apertures 134 of the shutter 130 are aligned with the apertures 123 in the bridge member 121. In the inoperative position of the lampholder the apertures 134 and 123 are nonaligned.

The shutter 130 locates in the housing 110 in the gap defined between the terminal block 170 and bridge member 121 and is movable angularly within said gap between an inoperative position and an operative position. The limbs 131 of the shutter extend internally in the housing 110 through the arcuate slots 122 on either side of the bridge member 121 to locate respectively on the support ledges 117. The cutouts 132 of the shutter 130 are positioned so as to be engagable by the bayonet pins of an inserted bulb.

A contact plate 140 is also provided having a central aperture 142 which locates .on the peg 128 and a pair of spaced apertures 141 to receive bulb engaging contacts 145. The contacts 145 which are of cylindrical form closed at one end and retained by means of the shoulder 146. When assembled the said contacts 145 extend from the surface of the contact plate 140 facing the shutter 130. A pair of bearing surfaces 143 are defined on ti.e contact plate 140 to engage in use the ramp/cam surfaces 137 defined on the shutter 130.

111 JSS290493 When no bulb is present in the lampholder the bearing surfaces 143 are located in their respective indent or holding recesses 138 at the top of the ramp/cam surfaces 136.

The contact plate 140 is positioned in the housing 110 in the gap defined between the shutter 130 and terminal block 170 and is movable axially within said gap and within the limbs 175 depending from the terminal block 170. It is movable between two positions, namely a first position, in which the contacts 145 on the contact plate 140 are inaccessible behind the shutter 130, and a second position in which the said ooo.

contacts 145 and contact plate 140 have been moved axially outward of the housing 110, with contacts 145 extend through the two pairs of apertures 134 and 123 in the shutter and bridge member respectively so as to be engagable by the pad contacts of a bulb inserted into the lampholder.

A bridging contact carrier 151 is also mounted in the housing 110 and locates in a gap defined between the contact plate 140 and terminal block 170. It is movable axially within said gap and within the support limbs 175 defined on the terminal block 170. The contact carrier 151 is provided with a pair of spaced apertures 152 to receive bridging contacts 149 respectively which are retained therein by means of the shoulder 150.

The contacts 149 are typically either cylindrical or fabricated from flat metal strip and closed at one end.

Support bridging springs 148 locate within the contacts 149, with the other end of said springs 148 locating within the contacts 145 on the contact plate 140. Thus, the springs 148 provide a resilient electrical bridging connection between the two pairs of contacts 149 and 145 respectively.

In the operative position of the lampholder the bridging contacts 149 effect electrical connection between the pair of bulb engaging contacts 145 mounted in the contact plate 140

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JSS290493 and the pair of flex terminals 171 mounted on the terminal block 170 respectively. The contact carrier 151 also defines a central cam following bearing surfaces 153 positioned so as to be engaged by a shaped cam member 161 defined on the surface of a switch actuating member 160 facing the contact carrier 151.

In this embodiment, a switch actuating member 160 is also slidably mounted in the housing 110 and has ena positions 167 ooooo: S which locate in the cut-outs 120 respectively. The actuating member 160 is assembled in the housing 110 in the gap defined between the contact carrier 151 and terminal block 170 and is slidable within the cut-away portion 154 in the contact carrier 151. It is positioned such that the shaped cam surface 161 engages the cam following bearing surface 153 on the contact carrier 151. The switch actuator member is also spring biased inward of the housing 110 by the said contact carrier 151. The cam surface 161 on the actuator 160 has a short 'OFF' side 163 and a long 'on' side 162. Thus, on moving the actuator 160 transversely from its 'ON' to its 'OFF' position, axial movement of the contact carrier 151 is S arrested prematurely by the raised surface 164 defined on the said actuator 160 prior to an electrical connection being made between the bridging contacts 149 on the contact carrier 151 and the pair of flex terminals 171 on the terminal block respectively. This is best illustrated in Fig. 4e, The bridging compression springs 148 urge the contact carrier 151 and thereby the cam follower 153 against the cam 161 to provide an over-centre mechanism interconnecting the actuator 160 and contact carrier 151. The actuator 160 can be moved transversely between its 'OFF' and its 'ON' positions in conventional manner whether or not a bulb is present in the lampholder said movement is limited in both directions by the lugs 165 which engage the housing 110.

In use, the lampholder of Fig. 4 is assembled and when no

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JSS290493 17 bulb is present the lampholder components assume the position illustrated in Fig. 4b. The cut-outs 132 are aligned with the axial portion of the slots 111. As a bulb is inserted into the lampholder in a conventional manner the bayonet pins of the bulb move along the slots 111 to engage the cat-outs 132. Rotation of the bulb causes the shutter 130 to rotate with it, thereby rotating the ramp/cam surfaces 136 relative to the contact plate 140, moving said contact plate 140 axially inward of the housing 110 against the force of the S compression springs 148 raising the bearing surfaces 143 out of the indents or holding recesses 138.

Continued rotation of the shutter 130 causes the bearing surfaces 143 to move axially outward of the housing 110 following the ramp/cam faces 138 respectively (the contact plate 140 spring biased outward of the housing 110 by the springs 48). Simultaneously the pairs of apertures 134 and 123 in the shutter and bridge member respectively are aligned as the shutter 130 moves angularly relative to the housing 110.

The angle and length of incline of the ramp/cam surfaces 137 provide that said pairs of apertures 134 and 123 are fully aligned prior to the bulb engaging contacts 145 on the contact plate 140 extending through said pairs of apertures 134 and 123 to bear against their respective pad contacts of the inserted bulb. In this second operative position, the actuator in its 'ON' position the lampholder components are arranged as illustrated in Fig. 4d.

Fig. 4e illustrates the position of the components in the second operative position, with the actuator 160 having moved to its 'OFF' position. Axial movement of the contact carrier 151 has been arrested prior to electrical connection being made between the pair of bridging contacts 149 and the pair of flex engaging terminals 171 respectively. As the shutter 130 is rotated on removal of a bulb, the ramp/cam JSS290493 surfaces 136 drive the contact plate 140 and thereby the contacts 145 axially inward of the housing 110 against the force of the springs 148. The contacts 145 are thus driven back through the apertures 23 and 134 in the bridge member 121 and shutter 130 respectively until the contacts 145 are inaccessible behind the shutter. At this stage the shutter 130 has closed off the apertures 123 and the lampholder components resume the position illustrated in Fig. 4c with the bearing surfaces 143 relocated in the indents of recesses 138 S at the top of the ramp/cam members 136.

Referring now to Fig. 4 this illustrates how conveniently, from a manufacturers point of view, the proposed switched lampholder of the invention can be converted to a non-switched version by simply removing or not including in the assembly the switch actuator 160, bridging contacts 149 and the contact carrier 151. In this example the bridging springs 148 directly engage the flex terminals 171. The terminals 171 are fashioned at numeral 174 allowing them to locate within the springs 148. Alternatively, bores 176 may be provided in the terminal block 170 to support springs 148.

An injection moulding tool for forming may be provided with inserts to blank out the actuator cut-outs 120 in the housing 1. 0. It will thus be appreciated that a manufacturer may produce both types of lampholders from one set of moulding tools, metal components would be common and automatic assembly costs and other associated costs would be kept to a minimum.

Turning to Figs. 5a, b and c, this is an alternative embodiment of the present invention in which the ramp/cam surfaces 136 are defined internally on the housing 110. In this embodiment the contact plate 140' is engaged and driven angularly by the shutter 130' (or other rotating member). The contact plate 140' is rotated axially outward of the housing 110 with contacts 145 passing through the apertures 134 and 123 in the shutter and bridge member respectively to engage the pad contacts of an inserted bulb.

g"e I II JSS290493 19 The bridging springs 148 flex to accommodate the angular* movement of the contact plate 140' relative to the contact carrier 151. On removal of a bulb the shutter 130' drives the contact plate 140' axially and rotationally inward of the housing 110 against.the force of the springs 148 to the first position in which the bearing surfaces 143 are located in the indents or holding recesses 138 and the bulb engaging contacts are safe behind the shutter. All other aspects of this embodiment are similar to that of the embodiment of Fig. 4.

All the components.of the lampholder, with the exception of the springs, metal contacts and terminals can be moulded from a suitable non-conductive thermoplastics material.

Referring now to Figs. 6 to 6e there is illustrated an alternative shuttered lampholder comprising a hollow cylindrical housing 210 of a bayonet type bulb, having conventional slots 211 to receive the bayonet pins respectively of a bulb. The housing 210 is also provided with a plain band 214 intermediate its-ends. The plain band 214 defines cut-outs 216 to accept clips of a clip-on type cover (not illustrated). Located. in the housing 210 is the bridge support member 221 having apertures 223 and a pair of arcuate slots 222 adjacent to the housing wall. Peg 228 is defined S centrally on the inner surface of said bridge member 221, and S support ledges 217 and 227 are defined internally in the housing 210, together with vertical flat faces 218.

The other end of the housing 210 is closed by a terminal block 280 which is disc shaped and provided with two flat faces 283 which on assembly engage the flat faces 218 defined in the housing 210 to prevent relative rotation.

The terminal block 280 supports a pair of flex engaging terminals 281 which extend through said terminal block so as to be exposed on opposite sides thereof. Limbs 284 are defined on and deoend from the surface of the terminal block o .J

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C c L _I a JSS290493 facing the bridge member 221. The limbs 284 prevent the contact carrier 240 rotating relative to the housing 210.

A shutter member 230 in the form of a disc has two spaced apertures 232, a central aperture 231 and two cut-outs 233 on its periphery. The shutter 230 is movable between first and second positions.

A contact carrier 240 also locates in the housing 210 in :geeI a gap defined between the rotatable member 230 and is movable axially within said gap between first and second positions.

A central blind bore 242 and two contact receiving apertures 241 are provided in said contact carrier 240. A bearing

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surface 243 is provided at each end of said contact carrier, elongated slots 244 retain the bridging strip contacts 260 in said contact carrier said contacts 260 resiliently connected to the bulb engaging contacts 250.

A rotatable member 270 is mounted in the housing 210 in the gap defined between the terminal block 280 and contact carrier 240. The member 20 is rotatable with respect to the terminal block 280 and contact carrier 240 between first and second positions. The rotatable member 270 comprises a hollow cylindrical housing defining a pair of limbs 271 which extend therefrom to the housing slots 211. The limbs 271 define slots 272 for engagement with the bayonet pins of an inserted bulb. The housing slots 211 and rotatable member slots 272 are arranged such that insertion of a bulb causes the rotatable member 270 to rotate from its first to its second positions and removal of a bulb causes the rotatable member 270 to rotate from its second to its first position.

A compression spring 234 is positioned centrally in the housing 210, with one end of said spring 234 passing through the central aperture 231 in the shutter 230 to locate on and be supported by the bridge member 221. The other enC of the spring 234 is retained within the blind bore 242 on the I r L I JSS290493 contact carrier 240. This spring 234 acts to bias the contact carrier 240 inward of the housing 210 to its first position.

The limbs 271 of the rotatable member 270 engage the cutouts 233 in the shutter member 230 and provide that movement of the rotatable member 270 on bulb insertion from its first to its second position rotates the shutter 230 from its first to its second position. This aligns the pair of apertures 232 in the shutter 230 with the pair of apertures 223 in the housing bridge member 221 respectively. On bulb removal the rotatable member 270 is moved back to its first position moving the shutter 230 back to its first position non-aligning said two pairs of apertures 232 and 223.

In this embodiment the rotatable member 270 is characterised in that it defines angled/cam surfaces 273 in its wall 274. These angled/cam surfaces 273 engage bearing surfaces 243 respectively on each end of the contact carrier 240 and provide that as the rotatable member 270 is rotated on bulb insertion it drives the contact carrier 240 axially outward of the housing 210 against the force of the central return spring 234 from its first to its second position. This action also rotates the shutter 230 aligning the pairs of apertures 232 and 223 in said shutter and bridge member 221 allowing the bulb engaging contacts 250 to pass through said pairs of apertures to engage the pad contacts of an inserted bulb.

The bulb engaging contacts 250 are retained in the contact carrier 240 by means of the shoulder 251. These contacts 250 are preferably in the form of hollow metal spinnings closed at one end.

The bridging contacts 260 are also preferably fabricated from flat metal strip and are retained in the contact carrier 240 by means of their edges 263 which engage the elongated slots 244. The ends 262 of the contacts 260 bias the bulb I I I JSS290493 22 engaging contacts 250 in resilient fashion against the contact carrier 240 to their first position. The other end 261 of the bridging contacts 260 engage the flex terminals 281 in the terminal block 280 in a resilient, wiping, self cleaning fashion, which conveniently presents minimal resistance to the central automatic return spring 234 as it biases or returns the contact carrier 240 and thereby the rotatable member 270 to their first inoperative positions. As the central return spring 34 is supported by the housing bridge member 221 its forces are not transferred to the slot resting points.

In use, when the lampholder of Fig. 6 is assembled and with no bulb present, the lampholder components assume the position illustrated in Fig. 6b and 6d. The cut-outs 272 are aligned with the axial portion of the slots 211. As a bulb is inserted into the lampholder in conventional manner the bayonet pins move along the slots 211 to engage the cutouts 272. Rotation of the bulb causes the rotatable member 270 to rotate with it thereby rotating the shutter 230 and the angled/ramp surfaces 273 relative to the bearing surfaces 243 on the contact carrier 240. As before, this action moves the said contact carrier 240 axially outward of the housing 210 against the force of the return spring 234 while simultaneously the pairs of apertures 223 and 232 in the bridge member and shutter 230 respectively are al.gned and the bulb engaging contacts 250 extend through said pairs of apertures 223 and 232 to bear against their respective pad contacts of the inserted bulb, and to go under independent tension against said pad contacts (best illustrated in Figs.

6c and 6e).

As the rotatable member 270 is rotated on removal of a bulb the central compression spring 234 urges the contact carrier 240 and thereby the cam following bearing surfaces 243 against the angled/cam surfaces 273 of the rotatable member 270, driving the contact carrier 240 axially inward of the cl JSS290493 23 housing 210. The bulb engaging contacts 250 are drawn back through the pairs of apertures 223 and 232 and the shutter 230 closes off the apertures 223 in the bridge member 221, so that the lampholder components resume the position illustrated in Figs. 6b and 6e.

Turning now to Figs. 7a to 7c, they illustrate an alternative contact/terminal assembly in which a compression spring 355 has been interposed between the bulb engaging contact 350 and a modified bridging contact strip 360. The bridging contact 360 is retained in the contact carrier 340 by means of a barb 365. A rib 345 positions a leg 361 of contact 360 prior to assembly (see Fig. 7a). Fig. 7b illustrates the arrangement of the components prior to bulb insertion and Fig. 7c with bulb inserted.

As regards Figs. 8a and 8b, they illustrate a further S example of a resilient contact/terminal assembly, this time incorporating a compression spring 456. One end of this spring 456 locates within the bulb engaging contact 450. The other end bears directly against the flex terminal 481. Fig.

8a illustrates the arrangement of the components prior to bulb o I S insertion and Fig. 8b with bulb inserted.

Turning now to Figs. 9a to 9d, they illustrate an alternative embodiment which differs from the lampholder of Figs. 8a to 8b only in that a rotatable member 670 is provided with an internal bridge portion 676. This bridge portion 676 replaces the shutter 530 of the previous embodiments. A central aperture 677 and two spaced apertures 678 are defined in said bridge portion 676. In the first position of the rotatable member 670, the bridge portion 676 closes off the apeztures 623 in the housing bridge 621. As the rotatable member 670 is rotated on bulb insertion it uncovers apertures 623 to allow the bulb engaging contacts 650 to pass through to engage their respective pad contacts of an inserted bulb.

1 JSS290493 24 Another alternative embodiment is shown in Figs. 10a to Here a shuttered lampholder comprises a hollow cylindrical housing 710 having slots 711.

The other end of the housing 710 is closed by a terminal block 780 which is generally disc shaped but provided with flat faces which engage corresponding flat faces defined in the housing wall to prevent relative rotation. The terminal block 780 is a snap-engaging fit in the housing 710 and is supported on a shelf 719. Limbs 784 are defined on and depend from the inner face of the terminal block. The terminal block also supports a pair of resilient flex engaging terminal/contacts 760 which extend through said terminal block 780 so as to be exposed on opposite sides thereof.

A shutter 770 locates in the housing 710 on the support ledge 717 and is rotatable by engagement with an inserted bulb between closed and open positions. The shutter 770 has spaced apertures 776 and a pair of vertical slots 772. The housing slots and shutter slots 772 are arranged such that insertion of a bulb causes the shutter 770 to rotate from its closed to its open position and removal of a bulb drives the S shutter from its open position back to its closed position.

:.E

This shutter 770 is particularly characterised in that it defines cam surfaces 774A and 774B in its wall 777. These cam surfaces engage cam following bearing surfaces 743 defined on the axially movable member 740.

Rotation of the shutter 770 on bulb insertion causes the cam surfaces 774A to engage the bearing surfaces 743 moving the axially movable member 740 outward of the housing 710 from its first to its second position, thereby rotating the shutter 770. On removal of a bulb the cam surfaces 774B engage the bearing surfaces 743 and move the axially movable member 740 inwards of the housing 10 back to its first inoperative position.

~IP~L~ I JSS290493 The resilient terminal/contacts 760 are engaged by the axially movable member 740. The terminal/contacts 760 locate in cut-outs 742C and are preferably a snap-engaging fit therein and preventcd from relative rotation by the lugs 744.

As the axially movable member 740 is moved on bulb insertion from its first to its second position it extends the resilient terminal/contacts 760 outwards of the housing 710 against the resistance of said terminal/contacts 760. The ends 763 of said terminal/contacts 760 pass through the apertures 767 in the shutter 770 to engage their respective pad electrodes 790 of an inserted bulb.

As before, in use when the lampholder of Figs. 10a and is assembled and with no bulb present, the lampholder components assume the position illustrated in Fig. 10a. As a bulb is inserted into the lamphclder in conventional manner the bayonet pins move along the slots 711 to engage the cutout.3 772. Rotation of the bulb causes the shutter 770 to rotate with it, causing the cam surfaces 774A to engage the cam following bearing s-urfaces 743 thereby moving the axially :i movbl.e member 740 outwards of the housing 710 against the force of the terminal/contacts 760 from its first to its second position. Simultaneously, the apertures 776 in the shutter 770 are rotated clear of the limbs 784 depending from the terminal block 780. The axially movable member 740 extends the terminal/contact 760 outward of the housing 710 such that the ends 763 extend through the pair of apertures 776 in the shutter 770 to engage their respective pad electrodes 790 of the inserted bulb, (ref Fig. lOb).

On bulb removal, as the shutter 770 is rotated to move the axially movable member 740 inwards of the housing 10, the ends 763 of the terminal/contacts 760 passing back through the apertures 776. The limbs 784 close off the apertures 776 so that the terminal/contacts 760 are once again inaccessible and llyl LLIIIIIIII I I -Y e JSS290493 26 not visible behind the shutter 770.

Another alternative is shown in Figs. lla and llb. This incorporates a rotatable member 870 defining cam surfaces 874A and 874B which interengage cam following bearing surfaces 843 defined on the axially movable member 840. The provide that, on bulb insertion as the rotatable member 870 is moved from its first to its second position, it moves the axially movable member 840 outwards of the housing 810 from its first to is second position.

A bridge member 821 is defined in the housing 810, having S a pair of apertures 823, a pair of arcuate slots 822 and upstanding limbs 829. Flex engaging terminals 881 are supported by a terminal block 880 and electrically isolated from bulb engaging bridging contacts 860 mounted in the axially movable member 840 when no bulb is piesent in the lampholder. The bulb engaging ends 862 of the contacts 860 are inaccessible within the housing 810 behind the bridge member 821 when no bulb is present.

The rotatable member is supported on the ledge 817, and is rotatable with respect to the housing 810 and axially movable member 840 between first and second positions, The rotatable member 870 comprises a hollow cylindrical housing defining a pair of limbs 871 which extend therefrom to the housing slots 811, the limbs 871 having slots 72 for engagement with the bayonet pins of an inserted bulb are arranged such that insertion of a bulb causes the rotatable member 970 to rotate.

The axially movable member 840 locates in the housing 810, in its bearing surfaces 843 locating respectively in the cut-outs 873 in the wall of the rotatable member 870 and is movable axially within said gap and within the limbs 884 depending from the terminal block between first and second positions. Cam following bearing surfaces 843 defined on the ,e a- I JSS290493 27 axially movable member 840 engage cam surfaces 874A and 874B defined on the rotatable member 870. A compression spring 834 is mounted centrally on the internal surface of the bridge 821, the other end of said spring locating in a bore in movable member 840. The spring acts to bias the axially movable member 840 inwards of the housing 810 to its first position.

A pair of bridging contacts 860 are supported by the axially movable member 840 and positioned so as to be accessible on opposite sides thereof said contacts 860 in the second operative position of the axially movable member 840 effect electrical connection between the power supply flex terminals 881 and the pad electrodes 890 of an inserted bulb, said electrical connection being broken on bulb removal.

It will be appreciated that the lampholder may be employed in a manner similar to that described for previous embodiments.

Claims (14)

1. A safety lampholder for a bayonet bulb comprising a body defining slots to receive bayonet pins of an inserted bulb, contacts within the body for electrical connection to a power source to supply electricity to the bulb, rotatable apertured shutter means in the body for selectively obstructing access to the contacts and arranged so as to be actuable upon rotation of the bulb, and projecting surface formations within the body capable of actuating axial displacement of the contacts, relative to the shutter means and upon rotation of the shutter means, between a first inoperative position in which the contacts are behind the rotatable shutter means and a second operative position in which they extend through apertures in the shutter means for bearing against a bulb.

2. A lampholder according to claim 1 wherein the formations within the body provide cam surfaces for actuating axial displacement of the contacts.

3. A lampholder according to claim 1 or 2 wherein the ormations are provided on the shutter means.

4. A lampholder according to any preceding claim wherein the shutter means are engageable with an inserted bulb.

A lampholder according to any preceding claim wherein means are provided for shielding apertures in the shutter means when the contacts are in the inoperative position.

6. A lampholder according to claim 5 wherein the shutter means include two or more apertured members capable of relative rotation about a common axis between a first position in which the apertures are obstructed and a second position in which they are aligned. JSS290493 29

7. A lampholder according to claim 6 wherein at least one apertured member is fixedly mounted in the body.

8. A lampholder according to any preceding claim comprising a locking member biased towards a locked position in which it inhibits movement of the shutter means from the first to the second position, the locking member being releasable upon engagement with an inserted bulb.

9. A lampholder according to any preceding claim wherein the contacts bear against the surface formations within the body. e*

1 0. A lampholder according to any one of claims 1 to 8 wherein the contacts are located in an axially movable carrier which co-operates with the surface formations within the body Sto effect axial displacement of the contacts.

11. A lampholder according to claim 9 or 10 wherein biasing means are provided for urging the contacts or carrier into engagement with the surface formations.

12. A lampholder according to any one of the preceding claims wherein biasing means are provided for urging the contacts into the first inoperative position.

13. A lampholder according to any one of the preceding claims wherein means are provided for resisting rotational or angular displacement of the contacts.

14. A lampholder substantially as hereinbefore described with reference to, and as illustrated in, any one of the accompanying drawings. P. T. bokcRTy nj TuNE Iqqq- ~i U, ABSTRACT/FIG.1 SAFETY LAMPHOLDER A shuttered lampholder comprises a body (10) having slots (11) to receive bayonet pins of a bulb. Electrical contacts (60) are located in the body preferably within an axially movable contact carrier(30). A rotatable shutter (20) having apertures (26) is mounted in the body (10) for selectively obstructing access to the contacts Rotation of the shutter (20) is actuable, directly 3r indirectly, by rotation of the inserted bulb. The shutter (20) or other part of the lampholder has surface formations suitably of ramp form, to directly or indirectly actuate axial displacement of contacts (60) when the shutter is rotated, for example by moving the contact carrier The lampholder may assume a first inoperative position in which the contacts are located behind the shutter and second operative position in which they extend through apertures (26) in the shutter (20) so as to be available to supply electricity to an inserted bulb. e