GB2075277A - Lamp holder incorporating cord grip - Google Patents

Abstract

A lamp holder for electrical light bulbs, e.g. for Xmas tree decoration, comprising: an elongate body (2) moulded of electrically insulating thermoplastics material and having a socket therein to hold the light bulb; electrical contact elements (9) retained in the body (2) for engagement of electrical terminals of the lamp to be held in said holder; electrical wires (10) connected to the contact elements and extending therefrom longitudinally of the body; a support member (12) for the electrical wires moulded integrally with the body (2) to extend longitudinally thereof; a clamping member (15) moulded of electrically insulating thermoplastics material for co-operation with the support member (12) in a manner to trap the wires (10) between the two members (12, 15); and a sleeve (20) longitudinally slidable over the members (12, 15) to urge them towards one another such that they effect a tight gripping action on the wires (10) trapped between them and retain said wires substantially immovable with respect to the contact elements. As illustrated, the retention and trapping of the wires (10) is enhanced by providing the mutually facing surfaces (12, 19) of the members (12, 15) with mutually interdigitating projections (18, 14, 18) in the form of ridges directed transversely of the elongate body and away from said surfaces such as to deform the wires (10) and cause them to follow a sinuous path as they extend longitudinally of the two members (12, 15). <IMAGE>

Description

SPECIFICATION Electrical holders This invention relates to electrical holders and in particularto electrical lamp holders for holding an electrical light bulb provided with electrical terminals, and for making electrical contact with such terminals via electrical contact elements of the lamp holder.

Such electrical lamp holders for small light bulbs, e.g. as are used for decorating Xmas trees and the like, must have an appropriately high safety level yet be inexpensive to produce. One particularly important safety requirement is rendering the electrical wires to the electrical contact elements of the lamp holder substantially immovable with respect to the contact elements. In one proposed construction aimed at achieving this, the electrical lamp holder comprises an outer member which encompasses an inner member having the contact elements mounted therein, the electrical wires connected to the contact elements extending in and along elongate grooves following a tortuous path and formed in the outer surface of said inner member.Such a proposed construction is considered to suffer the disadvantage (a) of too high a production cost in that considerable time must be spent by a skilled assembly operative to lay the wires carefully and correctly in the tortuous-path-following elongate groove, and/ or (b) of requiring the maintenance of close manufacturing tolerances between the inner and outer members, and/or (c) of requiring complicated moulds and moulding techniques for producing the inner and outer members of plastics material.

It is accordingly deemed desirable for an alternative construction to be devised which can obviate one or more of the above-mentioned and/or other disadvantages.

According to this invention there is provided an electrical lamp holder for a light bulb provided with electrical terminals, said holder comprising: (a) an elongate body of electrically insulating material having a socket therein for holding the light bulb, said body retaining electrical contact elements therein for engagement of said electrical terminals; (b) electrical wires connected to said contact elements and extending therefrom longitudinally of said body; (c) a support member for said electrical wires, said support member extending longitudinally of the body and being longitudinally immovable with respect thereto; (d) a clamping memberforsaid electrical wires co-operable with said support member to trap said longitudinally extending wires between the two said members; and (e) a sleeve slidable longitudinally over the support member and clamping member to urge them towards one another such that the latter tend to effect a tight gripping action on the wires trapped between them and retain said wires substantially immovable with respect to said contact elements.

Preferably the mutually facing surfaces of said two members are provided with mutually interdigitating projections directed transversely of the body's longi tudinal direction and away from said surfaces such as to deform the electrical wires and cause them to follow a sinuous path as they extend longitudinally between the two said members.

Preferably said support member and/or said clamping member and/or said sleeve is/are of electrically insulating material, advantageously of plastics material.

Conveniently said body and said support member are each of plastics material and are moulded integrally with one another thereby to render them mutually immovable.

By way of non-limiting example, an electrical lamp holder according to this invention will now be described, reference being had to the accompanying drawing of which Figure 1 is an end elevation of the exemplary holder embodying this invention, Figure2 is a longitudinal cross-section generally along the line II - II of Figure 1, Figure 3 is a longitudinal cross-section generally along the line lil - lil of Figure 2 showing the clamping member 15 separately below, and Figure 4 is a transverse cross-section generally along the line IV - IV of Figure 2.

The illustrated exemplary holder 1 comprises an elongate, generally cylindrical body 2 having a socket 3 therein at the front of the body. The socket 3 is formed by a wide slot 4 extending diametrically through the body and having two pairs 6,7 of oppositely facing transverse grooves 5 in its side walls. Each of the two pairs of grooves 6,7 receives, in a tight sliding fit, a flat metal contact element 8, 9 respectively that is integrally formed with a tag connector 11. An insulated electrical wire 10 is crimped to each tag connector 11 so as to make electrical connection with the respective contact element 8, 9. The spacing between the two contact elements 8, 9 is substantially equal to the width of slot 4 so as to form the socket 3 with a generally square cross-section.The base of the socket 3 is provided by a cross-bar 13 which serves to separate the two tag connectors 11 and the two electrical wires 10 extending therefrom rearwardly of the elongate body.

The body 2 is moulded of electrically insulating thermo-plastics material integral with a rearwardly extending extension 12 of hollow generally semicylindrical cross-section. The extension is integrally provided centrally with an up-standing ridge 14 having a straight upper edge, and is integrally provided at its end with an end wall 16 of height fractionally less than half the diameter of the body 2, but having two laterally spaced, shallow, semicircular depressions 17 therein to accommodate the wires 10. The extension 12 thus serves as a support member to support the wires 10 as they extend rearwardly of the body 2.

A separate clamping member 15 is moulded of electrically insulating thermoplastics material to have a solid generally semicylindrical cross-section co-operable with the support member 12. The clamping member 15, shown separately in Figure 3, is integrally provided with two ridges 18 projecting away from the major flat surface 19 of clamping member 15, the ridges 18 being directed transversely of the cylinder axis and spaced apart longitudinally thereof such as to be disposed in planes one each side of the plane containing ridge 14. The height of the ridges 14 and 18 is such thattheirfree upper and lower surfaces respectively lie in horizontal planes spaced apart by a distance substantially less than thickness of the insulated electric wires 10 (see Figure 2).Accordingly as the clamping member 15 is brought into cylindrical contiguity with the body 2 and its extension support member 12, the wires 10 are compressed and deformed into following a sinuous path as they extend from body 2 past ridges 18,14,18 and end wall 16.

To achieve compression and trapping of the wires 10, and mutual approach of the members 12, 15 into mutual clamping co-operation, the two parts 2,15 are together slid into a hollow cylindrical sleeve 20 moulded of electrically insulating thermoplastics material to have an internal diameter substantially equal to the practically identical outer diameter of part 2 and parts 12, 15 combined, and also to have an encompassing flange 21 to assist in assembly and/or mounting of the lamp holder 1.

It will thus be apparent that due to the interdigitating nature ofthe ridges 18, 14, 18 the wires 10 are automatically trapped between members 12, 15 by assembly of the holder's three main parts and no skilled "threading" or laying wires into pre-formed grooves therefore is required. The three main parts, viz. body 2, clamping member 15 and sleeve 20, are all relatively simple mouldings of thermoplastics material (which, conveniently, may be of a green colour to blend in with the Xmas trees for which the lamp holders are primarily, but not exclusively, intended). Although it is desirable that the outer sleeve 20 fit tightly over at least members 12 and 15, it is not essential that very close manufacturing tolerances be maintained in order to achieve a sufficient clamping pressure on wires 10 since the latter are sufficiently trapped and rendered substantially immovable with respect to contact elements 8, 9 by a relatively light clamping pressure sufficient to effect the sinuous deformation of the wires 10 as illustrated in Figure 2. It will be appreciated that moulding the body 2 integrally with the support member 12 renders the latter immovable with respect to the body 2 (and to the contact elements 8, 9 firmly retained therein).

Claims (6)

1. An electrical lamp holder for a light bulb provided with electrical terminals, said holdercom- prising: (a) an elongate body of electrically insulating material having a socket therein for holding the light bulb, said body retaining electrical contact elements therein for engagement of said electrical terminals; (b) electrical wires connected to said contact elements and extending therefrom longitudinally of said body; (c) a support member for said electrical wires, said support member extending longitudinally of the body and being longitudinally immovable with respect thereto; (d) a clamping member for said electrical wires co-operable with said support member to trap said longitudinally extending wires between the two said members; and (e) a sleeve slidable longitudinally over the sup- port member and clamping member to urge them towards one another such that the latter tend to effect a tight gripping action on the wires trapped between them and retain said wires substantially immovable with respect to said contact elements.

2. A lamp holder according to Claim 1, wherein the mutually facing surfaces of said two members are provided with mutually interdigitating projections directed transversely of the body's longitudinal direction and away from said surfaces such as to deform the electrical wires and cause them to follow a sinuous path as they extend longitudinally between the two said members.

3. A lamp holder according to Claim or Claim 2, wherein said support member and/or said clamping member and/or said sleeve is/are of electrically insulating material.

4. A lamp holder according to any preceding Claim wherein said support member and/o(said clamping member and/or said sleeve is/are of plastics material.

5. A lamp holder according to any preceding Claim wherein said body and said support member are each of plastics material and are moulded integrally with one another thereby to render them mutually immovable.

6. An electrical lamp holder substantially as herein described with reference to and/or as illustrated in the accompanying drawing.