GB2360636A - Lampholder with earthing strip - Google Patents

Abstract

A lampholder has conductive cover 10 and an insulating insert (20). A metal strip 28 on the insert has a connection portion 36 and a contact portion 30. An abutment 32 on the insert holds the contact portion in contact with the cover 10. This allows the cover to be earthed more easily, and is more reliable than using a spring contact.

Description

9 2360636

Title: Lampholder Description of Invention

This invention relates to electric lampholders.

A lampholder conventionally comprises retaining means for a cap part of a light bulb, electrically conductive pins to engage a light bulb held in the retaining means and terminals adapted for connection to an electricity supply.

For aesthetic and reliability considerations, such a lampholder often comprises a metal outer pail which comprises, inter alia, the retaining means. The electrically conductive pins, contact means and terminals are provided in a non-conducting body which is received within the metal outer part to ensure that no electrical connection is made between the electrically conductive pins or electricity supply and the outer pail. For safety's sake, it is further desirable that the outer part be earthed, in particular connected to an earth connection of the electricity supply.

An aim of the invention is to provide a new or improved lampholder.

According to the present invention, we provide a lampholder having retaining means for a cap part of a light bulb, electrically conductive pins to engage a light bulb held in said retaining means and terminals for connection to an electrical supply, wherein the lampholder comprises an outer pail and inner part, the electrically conductive pins and terminals being provided on said inner part, the said inner part further comprising a connection means and a contact means to electrically connect said outer part to said connection means, and abutment means to maintain said contact means in contact with said outer pall.

Said abutment means and said contact means may be an interference fit within said inner part.

The abutment means may comprise a first abutment portion and a second abutment portion, wherein said first abutment portion may contact said 2 contact means, said second abutment portion may contact said outer part and said contact means may contact said outer part.

Alternatively, the abutment means may comprise a first abutment portion and a second abutment portion, wherein said first abutment portion may be spaced from said contact means, said second abutment portion may contact said outer part and said contact means may contact said outer part.

In either alternative, the contact means may contact an internal face of said outer part.

Said first abutment portion and said second abutment portion may be disposed on diametrically opposed faces of said inner part.

Said contact means preferably comprises a resiliently deformable wiper contact.

Said wiper contact is preferably provided on said inner part and comprises an end part resiliently biased outwardly from said inner part.

The contact means may be biased to a first position to hinder introduction of the inner pail into the outer part and may be movable to a second position to permit introduction of the inner part into said outer part.

Said inner part may be provided with second abutment means to hinder location of the inner part in said outer part when said contact means is in an outwardly biased position.

Said wiper contact and said connection means may be integrally provided.

Said connection means may comprise an earth connection means.

Said inner part may comprise a body comprising a non-conducting material.

Said outer part may comprise metal or a metallic material.

The invention will now be described by way of example only with reference to the accompanying drawings, wherein 3 Figure 1 is an exploded perspective view of a lampholder according to the present invention, Figure 2 is a section on line 2-2 of the assembled lampholder of Figure 1, and Figure 3 is a side view of part of the lampholder of Figure 1.

Referring now to the drawings, a lampholder is shown comprising an outer part comprising a lower housing part 10 and an upper housing part 11 which is releasably secured to the lower housing part 10 by a flanged sleeve 12 having an internal thread 13 which engages an external thread 14 of the lower housing part 10. The lower housing part 10 and upper housing part 11 have cooperating shoulders 15, 16. The lower housing part 10 comprises a first generally cylindrical part 10a, and a second, generally cylindrical part 10b of smaller cross-section of the first cylindrical part 10a. Interconnecting the generally first cylindrical pail 10a and the second cylindrical part 10b is a curved tapering part 10c. The upper housing part 11 comprises a first a first generally cylindrical part lla and a second generally cylindrical part 11b having a smaller cross-section than the first cylindrical part lla. The first generally cylindrical part 1 la and the second generally cylindrical pail 1 1b are connected by a frusto-conical part 11 c. The second generally cylindrical part 1 1b is provided with bayonet retaining means 17 to engage, in conventional manner, outward projections of the cap part of a light bulb (not shown). The lower housing part 10 is provided with a pair of vertically extending slots 18, 18' disposed mutually diametrically opposed to one another. Each slot 18, 18' has a lower edge, 18a, Wa respectively.

Also received on an external thread 19 on the second generally cylindrical part I la is a ring 19a adapted to hold a lamp shade or other attachment in place on said lamp holder.

Received within the outer pail is an inner part 20 comprising in the present example a body 20a comprising an upper portion 21 and a lower 4 portion 22 which are joined by a snap fit connection 23. The body 20a preferably comprises a non-conductive material. The inner part 20 is provided with electrically conductive pins 24 to engage, in conventional manner, the contacts of a light bulb (not shown) received in the retaining means 17, and terminals 25 to be connected to an electrical supply, and in the present example, a switch arm 26 to isolate the pins 24 ftom the terminals 25. In the present example, a switch mechanism indicated generally at 27 operable by the switch ann 26 comprises a safety switch mechanism as described in UK patent application no. GB 2319901 A, but of course any switch mechanism may be provided as desired, or indeed there may be no switch means provided within the inner part 20.

Provided on the inner part 20 is a connection means 28 having contact means in the form of a wiper contact 29. As seen in Figure 2, the wiper contact 29 has an outwardly extending hook-shaped upper part 30 and a lower, resiliently deformable part 31 extending around a portion of the body 20a. The body 20a is further provided with abutment means comprising, disposed on the body 20a adjacent the hook-shaped upper pail 30 of the wiper contact 29, a projection comprising a first abutment portion 32, and, on the opposite side of the body 20a to the first abutment portion 32, a pr jection comprising a second 01 abutment portion 33. The second abutment portion 33 further has a lower transverse surface 33a extending inwardly and horizontally from a lower pail thereof. The abutment means is of such a size to locate the body 20a relative to the lower housing 10 in a desired relationship, in the present example as explained below by (1) engagement of the second abutment means 33 with an internal face of the lower housing pail 10, (ii) engagement of the first abutment means with an inwardly directed face of the wiper contact 29 and (iii) engagement of an outer face of the wiper contact with an internal face of the lower housing part 10.

Although in the present example the abutment means comprises a pair of diametrically opposed projections, any suitable arrangement of abutment means could be provided, for example three projections at 120' spacing, or indeed any other suitable arrangement as desired.

In the present example, the connection means 28 further comprises an end part 34, received in a recess 35 provided in the body 20a shaped to provide an inwardly directed hook part 36 to engage an earth connection, for example the earth strand of a three-core wire. The wiper contact 29 is biased by resiliently deformable part 31 such that the upper pail 30 is spaced from the first abutment portion 32. The wiper contact 29 further comprises a shoulder 37 disposed between the resiliently deformable part 31 and the upper part 30. The connection means 28 may comprise a folded copper strip such that the end part 34, wiper contact 29 and upper part 30 are integrally provided, although any other suitable contact means may be used as desired.

The body 20a further comprises on a lower part thereof a first shoulder portion 38 disposed above the first abutment portion 32 and extending outwardly thereof and a second shoulder portion 39 disposed above the second abutinent portion 33 and extending outwardly thereof.

To ensure correct alignment between the inner part 20 and the upper housing part 11, the upper housing part 11 is provided with inwardly directed ridges 40 disposed on the internal face of the first cylindrical portion 1 la. The ridges 40 are disposed to extend parallel to the longitudinal axis of the upper housing part 11. The upper portion 21 of the body 20a is provided with corresponding recesses 41 to receive the ridges 40 when the inner part 20 is received in the outer part. In the present example, the upper housing pail 11 is provided with two ridges 40, and the body 20a comprises a pair of corresponding recesses 41.

To assemble the lampholder, the inner pail 20 is inserted in a generally vertical direction as seen in Figure 1 into the lower housing part 10 of the outer 6 part such that the switch arm 26 and first and second shoulder portions 38, 39 are received in the slots 18. In its biased position, the upper part 30 of the connection means 28 is spaced from the first abutment portion 32 such that the body 20a cannot be inserted into the position shown in Figure 2.

As the inner part 20 is introduced into the lower housing part 10, either or both of the following situations can occur. Either the shoulder 37 engages the lower edge 18a of the corresponding slot 18, or if the upper part 30 engages the lower edge 18a of the slot 18, the transverse surface 33a engages the lower edge Wa of the opposite slot 18', In either situation, the outward bias of the wiper contact 29 hinders any further introduction of the inner part 20 into the lower housing part 10.

To overcome the bias and to urge the inner part 20 into the position as shown in Figure 2, it is necessary to act on the inner part 20 such that the upper part 30 of the wiper contact 29 is urged towards the first abutment portion 32 and the shoulder 37 is received below the first abutment portion 32. In this position, the inner part 20 may be inserted into the lower housing part 10 such that the upper part 30 engages the lower pail 18a of the corresponding slot 18. The second shoulder portion 39 engages the lower part 18a of its corresponding slot 18, while the second abutment portion 333 engages an internal face of the lower part 10.

The dimension of the inner pail 20 between the outer faces of the first abutment portion 32 and the second abutment portion 33 is preferably selected such that the dimension of the body 20a and the wiper contact 29 is an interference fit within the first cylindrical pail 10a of the lower housing part 10 immediately below the slot 18a. This ensures that the wiper contact 29 is held firmly in abutment with the lower housing pail 10 of the outer part, to maintain the contact means in contact with the outer part.. The contact is not reliant on any biasing means of the contact to hold the wiper contact in contact with the 7 lower housing part 10 or any downward pressure being applied to the upper part 30 of the wiper contact 29.

Although it is preferable that the dimension of the body 20a and wiper contact 29 is an interference fit within the lower housing part 10, it may be desirable or may arise ftom manufacturing tolerances that there is some play between the abutment means and the lower housing part 10, i.e. there is not an exact interference fit. If this is the case, in the present example the second abutment portion 33 will engage an internal face of the lower housing part 10, the first abutment portion 32 will be spaced from said wiper contact 29 and the outward bias of the wiper contact 29 will maintain said contact means in contact with said outer part. The outward bias of the wiper contact 29 will thus hold the second abutment means 33 against an internal face of the lower housing part 10 and hence accommodate any such play between the body 20a and the lower housing part 10.

In either case, it is the engagement of the wiper contact 29 with an internal face of the lower housing part 10, by virtue of being an interference fit or due to the outward bias of the wiper contact 29, which provides a good electrical connection between the connection means 28 and the outer part of the lampholder.

Although in the present example the upper part 30 comprises a hook part 30a which lies alongside at least part of an outer face of the lower housing pail 10, it will be apparent that this hook pail 30a. may be substantially shorter without hindering good electrical contact between the wiper contact 29 and lower housing part 10.

The abutment portion 32 provides the further advantage of limiting the distance which the wiper contact 29 can be inwardly displaced. Repeated deformation of a resilient element can lead to plastic deformation and ultimately failure of the element. By restricting the distance which the wiper contact 29 can be displaced the extent of deformation of the wiper contact 29 8 can be limited and failure of the contact wiper avoided or at least deferred. The first abutment portion 32 thus helps maintain contact between the contact means and the outer part by ensuring that the resilient bias of the wiper contact is not weakened to the extent that the contact means is incapable of accommodating any play between the body 20a and lower housing part 10 as discussed above.

The cylindrical part 10b may provide a boss through which a suitable electrical cable may be passed, in the present example a three core cable having earth, live and neutral connections.

Although in the above described example and, as preferred, a bayonet type fitting is provided, the invention may be applied to a lampholder for a screw-in type lamp connection.

The invention may also be applied to lampholders for other kinds of lamp such as a fluorescent lamp having a similar single cap for being received and retained in a lampholder. In addition, the invention may be applied to lamps of the kind having two caps at opposite ends such as an incandescent or fluorescent tube where the lampholder is provided with two sockets, one for each cap.

In the present specification "comprise" means "includes or consists of' and "comprising" means "Including or consisting of'.

The features disclosed in the foregoing description, or the following claims, or the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for attaining the disclosed result, as appropriate, may, separately, or in any combination of such features, be utilised for realising the invention in diverse forms thereof.

9

Claims (16)

CLAIMS:

1. A lampholder having retaining means for a cap part of a light bulb, electrically conductive pins to engage a light bulb held in the retaining means and terminals for connection to an electrical supply, wherein the lampholder comprises an outer part and an inner part, the electrically conductive pins and said terminals being provided on said inner part, the inner part further comprising a connection means and a contact means to electrically connect said outer part to said connection means, and abutment means to maintain said contact means in contact with said outer part.

2. A lampholder according to Claim 1 wherein said abutment means and said contact means are an inteiference fit within said inner part.

3. A lampholder according to Claim 1 or Claim 2 wherein the abutment means comprises a first abutinent portion and a second abutment portion, wherein said first abutment portion contacts said contact means, said second abutment portion contacts said outer part and said contact means contacts said outer part.

4. A lampholder according to Claim 1 or Claim 2 wherein the abutment means comprises a first abutment portion and a second abutment portion, wherein said first abutment portion is spaced from said contact means, said second abutment portion contacts said outer part and said contact means contacts said outer pail.

5. A lampholder according to any one of the preceding claims wherein the contact means contacts an inner face of said outer part.

6. A lampholder according to Claim 3, Claim 4 or Claim 5 wherein said first abutment portion and said second abutment portion are disposed on diametrically opposed faces of said inner part.

7. A lampholder according to any one of the preceding claims wherein the contact means comprises a resiliently deformable wiper contact.

8. A lampholder according to Claim 7 wherein said wiper contact is provided on said inner part and comprises an end part resiliently biased outwardly from said inner body.

9. A lampholder according to Claim 8 wherein the contact means is biased to a first position to hinder introduction of the inner part into said outer part and is movable to a second position to permit introduction of the inner part into said outer part

10. A lampholder according to Claim 8 or Claim 9 where dependent directly or indirectly on Claim 3 or Claim 4 wherein said second abutment portion hinders location of the inner pail in said outer part when said contact means is in an outwardly biased position.

11. A lampholder according to any one of Claims 7 to 10 wherein said wiper contact and said connection means are integrally provided.

12. A lampholder according to any one of the preceding claims wherein said connection means comprises an earth connection means.

13. A lampholder according to any one of the preceding claims wherein said inner part comprises a body. comprising a non-conducting material.

14. A lampholder according to any one of the preceding. claims wherein the outer part comprises metal or a metallic material.

15. A lampholder as described herein with reference to the accompanying drawings.

16. Any novel feature or novel combination of features described herein and/or in the accompanying drawings.