GB1600848A

GB1600848A - Lampholders

Info

Publication number: GB1600848A
Application number: GB54305/76A
Authority: GB
Original assignee: IMI Kynoch Ltd
Current assignee: IMI Kynoch Ltd
Priority date: 1976-12-30
Filing date: 1976-12-30
Publication date: 1981-10-21
Also published as: ZA777539B

Description

(54) LAMPHOLDERS (71) We, IMI KYNOCH LIMITED (formerly Imperial Metal Industries (Kynoch) Limited), a British Company, of Kynoch Works, Witton, Birmingham B6 7BA, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- The present invention relates to lampholders and particularly, but not exclusively, to electric lampholders of the bayonet socket type.

It is known to have lampholders comprising a body adapted to receive and retain a lamp and also to retain a portion of insulating material, and a conductive structure mounted in the insulating portion, the conductive structure comprising a terminal portion for establishing electrical connection in use with a lead by which current is fed to or from the structure and a contact portion for establishing electrical connection in use with a lamp held by the body.

Lampholder bodies are conventionally of the bayonet socket or Edison-screw type.

While the present invention is concerned mainly with bayonet socket lampholders, certain aspects may be applied to Edison screw holders or to any other type of lamp retaining body. The body may be of metal, plastics, ceramic or any other desired, suitable material.

In conventional lampholder technology, the portion of insulating material is frequently referred to as the "interior" of the lampholder.

It is conventionally of ceramic or plastics material. It is generally dise shaped with an edge adapted to co-operate with the body to retain the insulating portion relative thereto.

A lampholder will normally comprise a plurality of separate conductive structures mounted in its insulating portion to establish respective electrical connections between plural input/output leads and corresponding contacts on a lamp. The structures mounted in a single lampholder may be virtually identical, or they may differ entirely. For ease of description and definition, one conductive structure only ("the conductive structure") is referred to below-any others in the same lampholders may be identical, similar (using the principles described herein although differing in detail) or entirely different.

According to the invention we provide a lampholder or an insert therefor having an insulating portion and a conductive structure passing through said insulating portion, the conductive structure being adapted to carry an electric current from a conductor lead to a lamp contact, wherein the conductive structure includes means adapted non-resiliently to clamp the conductor lead between itself and the insulating portion, and in which the conductive structure includes integral means for retaining a plunger contact for a lamp.

The plunger contact is typically in the form of a plunger which is spring loaded to ensure proper contact between the lamp and the plunger.

The conductive structure may include a strip which passes through a channel in the insulating portion. The strip may be suitably bent to provide one leg which is used to retain the plunger contact, and one leg which passes through the channel in the insulating portion.

The non-resilient clamping means suitably comprises a screw extending through a cooperating threaded orifice in the conductive structure. The conductive structure may also have integrally formed securing means adapted to secure said structure to the insulating portion. The securing means may comprise a portion of the conductive structure eg a strip which has been deformed. The deformed portion may take the form of a tag or tags formed on the conductive structure during the assembly of the conductive structure to the insulating portion. The tag or tags may be bent over an abutment in the insulating portion. Alternatively, the deformed portion is formed prior to the assembly of the conductive structure to the insulating portion, and snap fits into locations provided in the insulating portion upon assembly of the conductive structure to the insulating portion.

The channel through the insulating portion may be so shaped as to provide a passage for the connecting strip, and an adjacent passage for a conductor lead, the clamping screw being arranged so as to be able to clamp the conductor lead to the wall of the channel. The insulating portion, also called the interior, may have a suitable recess to per mit access to the head of the clamping screw.

By way of example only, several embodiments of lampholders in accordance with the invention will now be described with reference to the accompanying diagrammatic drawings in which: Figure 1 is a vertical section through a first plunger-type lampholder according to the invention, Figure 2 is a plan view of the interior of the lampholder shown in Figure 1, with the plungers omitted, Figure 3 is an exploded view of the contact/ terminal portions of the lampholder of Figure 1, Figure 4 is a sectioned side elevation of the interior of a second lampholder according to the invention, with associated partial plan view above and below it, Figure 5 is a side elevation of part of a terminal strip shown in section of Figure 4 Figure 6 is a sectioned side elevation of part of a third lampholder in accordance with the invention, Figure 7 is an end-plan of the part shown in Figure 6, Figure 8 is a side elevation of one element of the assembly shown in Figure 6, and Figure 9 is a partially sectioned side elevation of a complete lampholder assembly including the part shown in Figure 6.

The lampholder shown in Figure 1 comprises a body 10 forming a bayonet socket, although the invention is not limited to a socket of this type. An interior or insulating portion 12 of ceramic is held in the body 10 by any convenient means, not shown in the drawings. The interior 12 carries two plunger contacts 14 and two terminal/connector portions 16 (Figure 3) which will be described in further detail below. The plungers 14 and portion 16 are formed separately from each other. The body defines a generally cylindrical envelope within which the interior must lie.

The interior 12 has a pair of blind bores 18 opening on to the upper face ofthebodyas viewed in Figure 1 and receiving in use respective plungers 14 and springs 20 to urge those plungers outwardly from their respective bores. This arrangement is better seen in Figure 4, the lampholder of which is similar in this respect to that of Figure 1. Interior 12 also has another pair of bores 22 opening downwardly of the interior as viewed in Figure 1 and communicating on one side with slots 24 for a purpose now to be described.

Each connector/terminal portion 16 is formed from strip pressed into a first leg 26 and second leg 28. Leg 26 overlies the upper surface of the interior 12 in use and closes the end of the associated bore 22. Each leg 26 has an opening 30 to revive the associated plunger 14. The latter has a flange 33 at one end to engage the leg 26 and to prevent the plunger leaving the lampholder interior under the force applied by the spring 20.

The other leg 28 is located in a respective slot 24, and has projections 32 which can be deformed outwardly behind shoulders 34 (Figure 1) formed in that slot in order to hold the portion 16 in the lampholder interior by clamping the interior between them selves and the connector leg 26. Leg 28 also has screw-threaded opening 35 to receive a screw 36. The latter can be mated with its opening by way of a further slot 38 (Figure 2) extending transversely of each slot 24 and deep enough to give access to the opening 35 when the portion 16 has been secured in the interior 12.

Accordingly, the bared end of a lead wire can be inserted into one of the bores 22 from the lower face of the interior 12. The clamping screw 36 can be engaged with the screwthreaded opening 35 via the slot 38, and will clamp the lead wire in the bore 22 by forcing it against the ceramic interior 12. Current is then transferred to or from the associated plunger 14 by way of the terminal leg 28, and the connector leg 26. The surfaces defining slot 24 and facing bore 22 support the leg 28 when screw 36 is operated to clamp the lead against the ceramic. Tightening of the screw 36 also tightens the complete assembly,preventing excessive lateral movement of the associated plunger 14.

It will be appreciated that one advantage of the arrangement shown in the drawings is that no turned parts are required; the hollow plunger 14 and the portion 16 can both be made by pressing operations and the screw 36 can be forged. However, the invention is not limited to these forms of contact and terminal members and the various openings in the interior must be adapted to the selected form of a modified contact and/or terminal member. It will also be appreciated that the separate formation of the contact and terminal portions enables the body and interior portions to be shortened relative to conventional lampholders, and the integral formation of the terminal and connector portions reduces the number of parts to be assembled and the complexity of the assembly aperation.

The form of terminaVconnector portion 16 shown in Figures 2 and 3 is suitable for use with conventional plungers. By using smaller diameter plungers, e.g. of diameter about 3mm it is possible to use a straight leg 26 instead of the "cranked" leg shown in Figure 2. The interior 12 shown in Figure 2 has conventional cutouts to receive locating pieces on the body 10. Alternatively, the cutouts could be provided at the ends of the slots 38.

Clamping of the lead against the ceramic body, instead of within a block or tube of metal, substantially simplifies the formation of the terminal portion which can now be formed from strip metal by pressing. It also reduces the metal cost component in the production cost of the lampholder.

The section in Figure 4 is arranged to show one assembly of a lampholder plunger and terminal strip. Only this one assembly will be described, but it will be understood that the assembly is duplicated in the lampholder, as described above for Figures 1 to 3.

Figure 4 shows only the ceramic interior 40 of the second lampholder. In use the interior is mounted in a body of any convenient form and by any convenient means; for example the flange shown at the lower end of the interior in Figure 4 could be clamped between a lampholder body and cap as shown in Figure 9.

Interior 40 has a blind bore 42 receiving the open end of a tubular metal plunger 44. The other end of the plunger 44 is closed, and a compression spring 46 extends between the closed ends of the plunger 44 and the bore 42, so that the plunger is urged outwardly of its bore.

The interior 40 also has a through bore 48 which in use receives the electrical lead to supply current to or receive current from the plunger 44. Located beside and communicating with the bore 48 is a rectangular section slot 50 which receives one leg of a terminal/connector strip now to be described.

The terminal strip has two legs 52, 54 respectively, arranged at right angles to each other. Leg 52 lies in a suitable recess in the upper surface of the interior 40 and has an opening through which the plunger 44 projects. The diameter of this opening is such that the plunger is retained in the interior 40 by engagement of a flange 56 at the open end of the plunger with the leg 52 of the terminal strip. Leg 52 also has a flange 58 surrounding said opening to provide a sufficient area of contact between the leg 52 and the plunger 44 for transferring electrical current in use and to give additional support to the plunger.

The other leg 54 of the terminal strip has a window 60 cut from it adjacent its free end.

One metal portion 62 adjacent this window is cut free from the strip at one end 64 and is pressed outwardly from the strip to form a retaining tang. The resilience of the metal enables this tang 62 to be forced back into the general plane of the leg 54, but when the tang is released, it will return to its outwardly projecting position as shown in Figure 4.

At the lower end of the slot 50, as viewed in Figure 4, interior 40 is formed with two openings 66 to either side of the bore 48 (see the end plan view below Figure 4). Each opening 66 provides a shoulder 68 behind which a tang such as the tang 62 can locate and retain the terminal strip in the interior by a detent action. Thus, if the free end of the leg 54 is forced into the upper end of the slot 50, the tang 62 will first be deformed into the general plane of the leg 54, and will then snap behind one of the shoulders 68 when the leg is fully inserted.

Interior 40 has a further slot 70 extending from the slot 50 to the periphery of the interior, and providing access for a clamping screw to a screw-threaded opening formed in the leg 54 of the terminal. Thus, when an electrical lead is located in the slot 48, clamping screw 72 can clamp the lead between itself and the ceramic defining the slot 48.

Two shoulders 68 have been illustrated, but only one of these is necessary with the illustrated form of terminal strip. If the terminal strip had an integral central portion, with projecting tangs on each side, both shoulders 68 could be used as retaining shoulders. In the illustrated embodiment, the provision of both shoulders enables provision of the tang 62 on either side of the window 60.

In Figure 6 there is seen a ceramic interior 100 for a lampholder. The interior again has a pair of blind bores 120 (only one of which is seen in Figure 6). Each bore 120 receives a metal plunger contact 140 which is urged outwardly from its respective bore by a compression spring 160.

Each plunger 140 is prevented from leaving its associated bore by means of a flange 180 at one end of the plunger engaging a retaining annulus 200 integral with a terminal/connector strip 220. The strip 220 again has two legs arranged at right-angles, the free end of one leg providing the retaining annulus- 200 and the other leg extending into a slot 240 in the ceramic. The free end of this second leg is provided with a pair of tags 260, which are deformable out of the general plane of the strip.

The slot 240 extends completely through ceramic interior 100 and apens into a recess 280 in the face of the interior opposite that from which the plungers 140 project. The length of the terminal leg of the strip 220 is such that the tags project from the slot 240 into the recess 280. Thus, they can be deformed behind a retaining shoulder 300 provided within the recess, thereby retaining the terminal/connector strip, and hence the corresponding plunger, in position.

The recessed face of the interior 100 is also provided with two dome-shaped projections 320 aligned with respective blind bores 120.

One purpose of these domes 320 will be described later but it will be noted immediately that they permit shortening of the distance between the main faces of the interior while retaining an adequate length of bore 120 with an adequate thickness of ceramic at the blind end of each bore.

In use, the interior with its metal parts shown in Figures 6 to 8 is assembled in a metal body 340 (Figure 9). A flange 360 on the interior is clamped between the body 340 and a metal cap 380 by means of a clamping ring 400 which is inernally screw-threaded to engage external screw-threads on a skirt on the cap.

Electrical connections to the lampholder are made via a nipple 420 which screws into an opening in the cap, and through whch lead wires 440 can extend to connections with respective terminal strips 220. It is essential to ensure that there is no contact between the nipple 420 and a live terminal strip 220. Accordingly, the domes 320 are so arranged that they will be engaged by the inner end of the nipple 420 if the latter is screwed too far into the cap 380. The same spacing ensures adequate clearance for the leads 440 in their passage to the terminal strips 220. Adequate spacing of the nipple 420 and the terminal strips 220 is aided by the recesses 280, in which the tags 260 are arranged to lie.

The arrangement for connecting the leads to the terminal strips is as described above. A through-bore to receive the bared ends of the leads is shown at 460. Each terminal strip 220 has a screw-threaded opening 480 (Figure 8) recieving a clamping screw 500 (Figure 6) by means of which the lead end is clamped against the ceramic interior within the respective bore 460.

There are two domed projections in Figures 6 and 7 aligned with respective bores 120.

There could be a single bar extending across the rear face of the interior and performing the same functions but aligned with both bores 120. Where plural spacers are provided, the domed shape is not essential. The nipple type arrangement for feeding electrical connections to the interior is not essential, since the spacers are generally useful for preventing contact between terminal strips and conductive parts of the lampholder body. The bayonet type connection shown in Figure 9 for retaining the bulb is also not essential.

Other modifications will occur to those skilled in the art. For example, the elongate retaining annulus 200 may project outwardly from the interior instead of inwardly as illustrated.

This would facilitate further reduction in the distancebetween the main faces of the interior.

The recess which receives the leg 26 of the conductive structure shown in Figure 1, and the corresponding recesses in Figures 4 and 6 can be eliminated, so that the upper leg of the conductive structure stands proud of the ceramic interior. It is not necessary to use a blind bore to receive the compression spring for each plunger. A shelf at the lower end of each bore may provide support for the spring and even if the bore extends completely through the cermic.

Further, it is not essential to use a clamping screw to clamp the lead against the ceramic interior. A non-resilient connection is required to ensure retention of the lead in the clamp.

It will be appreciated that it is not essential for a bore to specifically receive the plunger.

Any opening which will permit the required travel of the plunger is satisfactory, since retention and guiding of the plunger is effected by reason of its contact with the conductive structure.

In connection with the performance of certain of the embodiments described herein, attention is directed to our co-pending applications 8016691 and 8016684. Serial Nos.

1600849 and 1600850.

WHAT WE CLAIM IS 1. A lampholder or an insert therefor having an insulating portion and a conductive structure passing through said insulating portion, the conductive structure being adapted to carry an electric current from a conductor lead to a lamp contact, wherein the conductive structure includes means adapted non-resiliently to clamp the conductor lead between itself and the insulating portion, and in which the conductive structure includes integral means for retaining a plunger contact for a lamp.

2. A lampholder or an insert as claimed in Claim 1 in which the conductive structure includes a strip which passes through a channel in the insulating portion.

3. A lampholder or an insert as claimed in Claim 1 or Claim 2 in which the non-resilient clamping means comprises a screw extending through a co-operating threaded orifice in the conductive structure.

4. A lampholder or an insert as claimed in any preceding claim in which the conductive structure has integrally formed securing means adapted to secure said structure to the insulating portion.

5. A lampholder or an insert as claimed in Claim 4 in which the securing means comprises a portion of the conductive structure which has been deformed.

6. A lampholder or an insert as claimed in Claim 5 in which the deformed portion comprises a tag or tags formed on the conductive structure during the assembly of the conductive structure to the insulating portion.

7. A lampholder or an insert as claimed in Claim 5 in which the deformed portion is formed prior to the assembly of the conductive structure to the insulating portion, and snap fits into locations provided in the insulating portion upon assembly of the conductive structure to the insulating portion.

8. A lampholder or an insert as claimed in Claim 3 as dependant upon Claim 2 in which the channel through the insulating portion is so shaped as to provide a passage for the conducting strip, and an adjacent passage for a conductor lead, the clamping

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

Claims

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

metal body 340 (Figure 9). A flange 360 on the interior is clamped between the body 340 and a metal cap 380 by means of a clamping ring 400 which is inernally screw-threaded to engage external screw-threads on a skirt on the cap.

Electrical connections to the lampholder are made via a nipple 420 which screws into an opening in the cap, and through whch lead wires 440 can extend to connections with respective terminal strips 220. It is essential to ensure that there is no contact between the nipple 420 and a live terminal strip 220. Accordingly, the domes 320 are so arranged that they will be engaged by the inner end of the nipple 420 if the latter is screwed too far into the cap 380. The same spacing ensures adequate clearance for the leads 440 in their passage to the terminal strips 220. Adequate spacing of the nipple 420 and the terminal strips 220 is aided by the recesses 280, in which the tags 260 are arranged to lie.

The arrangement for connecting the leads to the terminal strips is as described above. A through-bore to receive the bared ends of the leads is shown at 460. Each terminal strip 220 has a screw-threaded opening 480 (Figure 8) recieving a clamping screw 500 (Figure 6) by means of which the lead end is clamped against the ceramic interior within the respective bore 460.

There are two domed projections in Figures 6 and 7 aligned with respective bores 120.

There could be a single bar extending across the rear face of the interior and performing the same functions but aligned with both bores 120. Where plural spacers are provided, the domed shape is not essential. The nipple type arrangement for feeding electrical connections to the interior is not essential, since the spacers are generally useful for preventing contact between terminal strips and conductive parts of the lampholder body. The bayonet type connection shown in Figure 9 for retaining the bulb is also not essential.

Other modifications will occur to those skilled in the art. For example, the elongate retaining annulus 200 may project outwardly from the interior instead of inwardly as illustrated.

This would facilitate further reduction in the distancebetween the main faces of the interior.

The recess which receives the leg 26 of the conductive structure shown in Figure 1, and the corresponding recesses in Figures 4 and 6 can be eliminated, so that the upper leg of the conductive structure stands proud of the ceramic interior. It is not necessary to use a blind bore to receive the compression spring for each plunger. A shelf at the lower end of each bore may provide support for the spring and even if the bore extends completely through the cermic.

Further, it is not essential to use a clamping screw to clamp the lead against the ceramic interior. A non-resilient connection is required to ensure retention of the lead in the clamp.

It will be appreciated that it is not essential for a bore to specifically receive the plunger.

Any opening which will permit the required travel of the plunger is satisfactory, since retention and guiding of the plunger is effected by reason of its contact with the conductive structure.

In connection with the performance of certain of the embodiments described herein, attention is directed to our co-pending applications 8016691 and 8016684. Serial Nos.

1600849 and 1600850.

WHAT WE CLAIM IS 1. A lampholder or an insert therefor having an insulating portion and a conductive structure passing through said insulating portion, the conductive structure being adapted to carry an electric current from a conductor lead to a lamp contact, wherein the conductive structure includes means adapted non-resiliently to clamp the conductor lead between itself and the insulating portion, and in which the conductive structure includes integral means for retaining a plunger contact for a lamp.
2. A lampholder or an insert as claimed in Claim 1 in which the conductive structure includes a strip which passes through a channel in the insulating portion.
3. A lampholder or an insert as claimed in Claim 1 or Claim 2 in which the non-resilient clamping means comprises a screw extending through a co-operating threaded orifice in the conductive structure.
4. A lampholder or an insert as claimed in any preceding claim in which the conductive structure has integrally formed securing means adapted to secure said structure to the insulating portion.
5. A lampholder or an insert as claimed in Claim 4 in which the securing means comprises a portion of the conductive structure which has been deformed.
6. A lampholder or an insert as claimed in Claim 5 in which the deformed portion comprises a tag or tags formed on the conductive structure during the assembly of the conductive structure to the insulating portion.
7. A lampholder or an insert as claimed in Claim 5 in which the deformed portion is formed prior to the assembly of the conductive structure to the insulating portion, and snap fits into locations provided in the insulating portion upon assembly of the conductive structure to the insulating portion.
8. A lampholder or an insert as claimed in Claim 3 as dependant upon Claim 2 in which the channel through the insulating portion is so shaped as to provide a passage for the conducting strip, and an adjacent passage for a conductor lead, the clamping

screw being arranged so as to be able to clamp the conductor lead to the wall of the channel.
9. A lampholder or an insert therefor as claimed in Claim 1 and as hereinbefore described with reference to and as shown in Figures 1 to 3, or Figures 4 and 5, or Figures 6 to 9 of the accomDanving drawers.