GB2245776A

GB2245776A - Lamp holders

Info

Publication number: GB2245776A
Application number: GB9110419A
Authority: GB
Inventors: Gary Evett
Original assignee: Ranton & Co Ltd
Current assignee: Ranton & Co Ltd
Priority date: 1990-05-18
Filing date: 1991-05-14
Publication date: 1992-01-08
Also published as: GB9110419D0; GB9011231D0

Abstract

A lampholder comprising a body part (12) carrying lamp cap contacts (16) and requiring electrical connections thereto, the body part having slideway provision (32, 34), and blade means (20) engageable in the slideway provision (32, 34) to make electrical connection between a said lamp contact (16) and an electrical supply wire (39). Alternative wire accommodation (36) for each lamp contact, entries of connection blade means (20) from either end of slideways, and lampholder cap (14) orientations facilitate assembly. Preferred gripping of electrical cord (18) uses fingers (48) of the cap deflected during snap-on fitting of the cap (14) (figs. 1, 3). Alternatively (figs. 5, 7) fingers (148) are formed with a base (145) which is attached to lampholder body by engagement with lugs 132, 134. The fingers are actuated by the cap. <IMAGE>

Description

LAMPHOLDERS This invention relates to lampholders.

It has become a common practice to supply lampholders pre-wired with a short length of electrical cord, flex or cable for ready attachment to an electrical outlet accessory, normally a ceiling rose, even to provide same further connected into a ceiling rose. Self-evidently, prpviding a wired-up lampholder adds to product costs for the lampholder manufacturer.

Most cost is found to be added where the lampholder concerned is of screw-clamp type for electrical connections, hence general moves towards use of crimped connections, thus to pre-wired lampholders that are, in general practical terms, incapable of being rewired.

Non-rewirability is accepted herein.

Screw-clamp component parts are in such largescale and long-established production that there is actually little or no significant gain from substituting crimp type connectors, either from costs of their component parts or from lampholder assembly costs, i.e.

most of costs gain is in terms of time taken to wire up.

It is a general object of this invention to provide for wiring up of lampholders in a manner that produces some further economy of costs and/or improvement of certainty of electrical connection, say compared with the obvious alternative of spring-loaded grab-type connection provisions.

According to one aspect of this invention, there is provided a lampholder having a lamp cap contacts carrying body part to which electrical connection is to be made for electrical supply to its contacts, wherein making of said electrical connection(s) involves slideway provision(s) in said body part and sliding electrical connection making means for said slideway provision(s) to engage and make preferably gripping electrical contact with wire for electrical supply purposes and further make electrical connection with said contacts of the body part.

The latter electrical connection, i.e. with said contacts, is readily achieved by spring means for example as conventionally applicable to plunger type lamp cap contacts.

Usually, there will be two slideways, preferably parallel, one for each contact of the body part and corresponding wire to be in electrical connection therewith, and two slide-insertion connection-making means, both of which and related slideways may conveniently be transversely of innermost ends or parts of contact provisions of the body part.

It is particularly advantageous for the or each innermost end or part of the lamp cap contact provision(s) of the body part to be flanked in the direction of the corresponding slideway by electrical supply wire accommodations and for the slideway to permit entry of the connection making means in either direction, so that installation of the or each slideaction connection making means is tolerant of orientations of the body part differing by 1800. That is especially useful in relation to dual plunger type lamp cap contacts as typical for bayonet-fitting lampcaps, and where customary J-slots are natural location aids during assembly.

That gives rise to a further aspect of invention, namely a method of making electrical connections to a contact carrying body part of a lampholder, the method including installing one or more sliding contact making parts into one or more corresponding slideways in the body part in either of two orientations of the body part.

Preferred electrical connection making gripping of the electrical wire or wires is by disruption or displacement of its insulation due to action of the slidable electrical connection making part, typically a slotted IDC member whose slot sides break through such insulation.

Another factor for conventional lampholders that affects wiring up is normal provision of labyrinth systems for insulated electrical supply wires between entry through a cap of the lampholder and the actual electrical connections to the lampholder's contact carrying body part, or operation of outer insulating sheath gripping provisions of the electrical cord.

According to another aspect of this invention, there is provided a lampholder comprising a contact carrying body part to which electrical connections are made and a cap through which electrical cord having wires for said electrical connections is passed, the cap having internally projecting formation adjacent its cord entry position and the body part having or abutting another part having formation cooperating with the internally projecting formation of the cap to produce deflection of a part or parts of said formations towards and then gripping said cord.

In one embodiment, the cap and body part formations permit only axial relative movement as they interengage and the cap is a push fit onto the body part. Suitable cap formation comprises at least one deflectable finger extending towards the mouth of the cap, and suitable body part formation comprises at least one recess shaped to deflect said finger.

In another embodiment, the body part abuts a said other part having deflectable fingers as its said formations. A preferred said other part has an annular base to abut inner end of the body part and fit about a said electrical cord with its deflectable fingers extending away from the base and distributed about cordaccommodation aperturing thereof.

With such a preferred other part acting as a cord clamp device there is no need for said cap formations to interact with the fingers for preventing non-axial movement of the cap in deflecting the fingers, and the cap formation can be a simple inward neck gding about ends of the fingers. Moreover the annular base of the cord clamp device need not make irrotational abutment on the body part, the top of which may be at a single level above its slide ways. All of these features further contribute to ease of assembly, i.e. without any orientation requirement for the cord clamp device or the cap.

However, after assembly, relative rotations of the cord clamp device and the cap, or of either relative to the body part, are undesirable, and avoiding same gives rise to two features. One is at least one further interior formation of the cap by way of a rib capable of deforming an edge of the cord clamp base. The other is at least one cap-grip formation of the body part by way of a rib capable of deforming an edge of the cap.

A cord grip device having base and finger features as aforesaid, though not necessarily limited to lampholder applications, contributes a further aspect of this invention, and it is preferred where such device is operable by parts moving towards each other at base and finger ends, for the base to be dished from its rim out to its aperture from which its fingers extend, thereby improving flexure and resilience capabilities.

Specific implementation by way of one embodiment of this invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is an isometric view of a lampholder 10 having body (12) and cap (14) parts; Figure 2 is a top plan view of the body part 12; Figure 3 is an inverted sectional view on line A A of Figure 2 further showing the cap (14), lamp cap contact (16), electrical cord (18) and electrical connection making means (20); Figure 4 is a plan view of the electrical connection making means (20); Figures 4A and 4B show a modified connection making means (20'); Figure 5 is a perspective view of another lampholder body; Figure 6 is a top plan view thereof; Figure 7 is a perspective view of a cord grip device for the body of Figure 5; Figure 8 is a plan view of the cord grip device of Figure 7;; Figure 9 is a perspective view of lampholder cap for the body of 'Figure 5 and the grip device of Figure 7; Figures 10 and 10A are bottom plan and detail views of the cap of Figure 9; Figures 11 and llA are axial section and detail views of the cap of Figure 9; Figure 12 is a section through a lampholder assembled from parts as in Figures 5 to 11; and Figure 13 is a plan view of a bandolier of slide grips.

In Figures 1 to 4, body part 12 is shown with a sleeve 22 for accepting insertion of a lamp cap. The sleeve 22 has lamp cap retention provisions by way of lower conventional diametrically opposed J-slots 24 (one only shown) and upper external threading 26 for a shield or a shade ring below a flange 28 with grip-aiding bumps 28A,B. Internally, the body part 12 has depending well formations 30A,B accommodating plunger contacts 16 extending therefrom and loading springs 33 therefor. The well formations 30A,B are suitably located spatially relative to the J-slots 24 to assure lamp cap retention and contact by the plungers 16 as is well known.

Above the flange 28, the body part 12 has two slideway formations defined by spaced pairs of confronting returned lug formations 32A,34A and 32B,34B, the pairs for each slideway flanking a different one of entry apertures to the wells 30A and 30B. Shown between the lugs of each of the pairs 32A,32B,34A,34B are blind recesses 36 capable of taking free ends of conductors of electrical cord 18, see 39 in Figure 3. The slideways accommodate an electrical connector 20 shown as being of blade form with tapered ends 38A,B and slots 40A,B extending from each of those ends. A central part 42 of each blade connector 20 will pass over the corresponding entry aperture to the underlying plunger and spring accommodating well 30A or 30B, and makes electrical contact with the spring 33 concerned.Preferably, the connector blade slots 40A,B and the material of the blades 20 are consistent with making electrical contact with insulated wires 39 by disrupting or displacing their insulation.

An alternative approach, see Figures 4A and 4B, is to have the blade connector 20' engage a ferruled wire end 39E, i.e. an end bared of insulation and wrapped with a conducting metal sleeve. Then slot 40' is shown at a modified end of the blade connector 40', specifically with a medial enlargement 40H and an enlarged entry 40E to take the ferruled wire end 39E.

What is shown in Figures 4A,B can be taken as no more than a fragment of a double-ended blade connector, generally as in Figure 4, or as a single-ended blade connector.

It will be appreciated that use of insulation displacing or ferrule engaging blades 20 or 20' and related parallel slideways substantially eases making of electrical connections between lamp cap contacts (16) and electrical cord (18). Moreover, use of a doubleended blade 20 operative at either end, i.e. with two end slots 40A,B and preferably tapered top and bottom at its ends 38A,B further eases assembly to an electrical cord, especially in conjunction with provision of two electrical wire receiving recesses 36 one to each side of entries to the lamp cap contact having well formations 30A,B. Then, as well as 1800 attitude tolerance of the body part 12, which particularly facilitates location by either or both of the J-slots 24, say in an appropriate nest or cradle or other holder, there would be end-about and inversion tolerance for the blades 20.Even a single-ended blade 20' would, of course, be capable of insertion from either end of the slideways.

Also shown above the flange 28 of the body part 12 are diametrically opposed upstands 42A,B shown extending from between the slideways. The upstands 42A,B have confronting slot formations 44A,B shown extending down from top platform formations 46A,B. The slots 44A,B curve towards each other and will deflect finger formations 48A,B of the cap 14.

Those finger formations 48A,B are shown formed in an internal depending neck formation 50 by flanking axially extending pairs of slots, see 52A,B in Figure 1.

That forces one of two orientations of the cap 14 relative to the body part, it affords sheath gripping facilities for the electrical cord 18, see particularly toothed ends 54A,B of the fingers 48A,B. Snap action fitting of the cap 14 to the body part 12 is indicated by way of cap teeth 56 and body part undercuts 58.

The cap 14 can usefully further have formations, see 60 in Figure 3, by which ends of the blades 20 are secured against displacement in the slideways.

Turning to Figures 5 to 12, body part 112 differs mainly at its upper part above its flanging 128. Its slide-way formations, specifically lug formations 132A,134A and 132B,134B finish flush, see flats 132F and 134F, with dividing upstands, see flat 142F. The flats 132F,134F and 142F lie in a common transverse plane and present abutments for a cord grip device 144 at its annular base 145 having a body-abutting ring formation 145R and dishing 145D up to its central aperture 147.

The cord grip device 144 further has evenly spaced upstanding deflectable fingers 148 terminating in cord grip teeth formations 154. Deflection of the fingers 148 into cord-gripping action is by way of a tapered neck formation 150 of lampholder cap 114. The lampholder cap 114 is a snap-fit to the body part 112 by way of arcuate inner cap formations 156 relative to body part ledging 158.

In assembly, there is no directional or relative angular orientation requirement for the body part 112, the cord grip device 144, and the cap 114, or any two of them. After assembly, however, it is desirable that relative rotation be prevented. For that purpose, the cap 114 is shown with inner formation 162, actual four thereof, running down inner sides of the cap 114 to engage and locally deform at least outer rimming 164 of the cord grip device; and the body part 112 is shown with upstanding formation 166, actual two thereof, to engage and locally deform the cap 114 at its bottom edge when snap-fitting thereof is completed. The cap inner formations 162 are shown of sharp edged triangular form, see Figures 10A and 11A, and the body part formations 166 on its flange 128 may have similarly triangular formation to present cap deforming edges.

Materials for the cap 114 and cord grip device 144 can, of course, be of cheaper and softer material than needed to meet electrical requirements of the body part 112.

Figure 13 shows blades 120 that are one-sided for contact making slots 140, and supplied in bandolier form for snapping-off or cutting to fit into the lampholder slideways. Apertures 141 between contact blades 120 can assist transport, but will become waste at taking the blades 120 off, whether by snapping or by cutting using a small press-tool wider than the width of the bandolier and its carrier and could take out the intended scrap in single operations of the press-tool.

Claims

1. A lampholder comprising a body part carrying lamp cap contacts and requiring electrical connections thereto, the body part having slideway provision, and means engageable in the slideway provision to make electrical connection between a said lamp contact and an electrical supply wire.

2. A lampholder according to claim 1, wherein said slideways extend transversely of said body part and its said lamp contacts.

3. A lampholder according to claim 2, wherein the electrical connection making means is operative to disrupt insulation of said wire.

4. A lampholder according to claim 3, wherein the electrical connection making means comprises a blade of electrical conducting material slidable into and then retained by the slideway provision.

5. A lampholder according to claim 4, wherein electrical connection between said blade and said lamp contact is by way of a conductive compression spring.

6. A lampholder according to claim 5, wherein said spring is of a plunger type said lamp contact.

7. A lampholder according to any preceding claim, wherein the body part has two said slideways, one for each of two said lamp contacts and two said electrical supply wires.

8. A lampholder according to claim 7, wherein the slideways are parallel with each other.

9. A lampholder according to any preceding claim, wherein the body part has spaced possible accommodations for each said wire, which accommodations flank a position in the or each slideway whereat lamp contact connection is made.

10. A lampholder according to any preceding claim, wherein said electrical connection making means is enterable said slideway provisions from either end thereof.

11. A method of making electrical connections to a lampholder body part carrying lamp cap contacts accessible via slideway provisions, the method comprising inserting insulated electrical supply wires into accommodations therefor through the slideway provisions, and inserting electrical connection making means into said slideway provisions to disrupt insulation of said wire.

12. A method according to claim 11, wherein it is immaterial from which ends of said slideway provisions said electrical connection making means is inserted.

13. A lampholder according to any one of claims 1 to 10, further carrying a cap for said body part through which cap electrical supply cord is passed, the cap having internally projecting formation adjacent its cord entry position, and the body part having or abutting another part having formation cooperating with the internally projecting formation of the cap to produce deflection of a part or parts of said formations towards and then gripping said cord.

14. A lampholder according to claim 13, wherein the cap is a push fit into the body part.

15. A lampholder according to claim 14, wherein said other part is a cord grip device having deflectable fingers for engaging and gripping said cord.

16. A lampholder according to claim 15, wherein said cord grip device has an annular base to abut said body part and said fingers extend away from the base.

17. A lampholder according to claim 16, wherein said body part has coplanar flats to abut said annular base of the cord grip device.

18. A lampholder according to any one of claims 14 to 17, wherein said cap has an inward neck as its said formation.

19. A method of assembly a pre-wired lampholder comprising the method of claim 11 or claim 12, followed by fixing a cord grip device by deflecting fingers thereof into engagement and gripping of an electric cord by coaction of the lampholder body part and a lamp cap fitting over the cord grip device and onto the body part.

20. A method according to claim 19, wherein annular orientation of the body part, the cord grip device and the cap are immaterial to assembly achieving cord gripping.

21. A lampholder according to any one of claims 13 to 18, wherein said cap has formations that locally deform said other part to prevent its rotation relative to the cap after assembly.

22. A lampholder according to any one of claims 13 to 18, or claim 21, wherein said body part has formations that locally deform said cap to prevent its rotation relative to the body part after assembly.

23. A lampholder according to claim 21 or claim 22, wherein said deforming formations comprise substantially triangular section ribs presenting a deforming edge.

24. A lampholder according to claim 13 or claim 14, wherein said formations of said cap and of said body part permit only axial relative movement as they interengage.

25. A lampholder according to claim 24, wherein said cap formation comprises at least one deflectable finger and cooperating said formation of said body part is a slot.

26. A lampholder substantially as herein described with reference to and as shown in Figures 1 to 4, or Figures 5 to 12, or Figure 13 of the accompanying drawings.

27. A method of prewiring a lampholder substantially as herein described with reference to the accompanying drawings.