GB2103776A - Disposable lamp - Google Patents

Abstract

A battery-lamp has a strip 22 of insulating material interposed between contacts 12 and 20 until the lamp is required for use. The strip is then removed to complete a circuit from the battery through a bulb 18. <IMAGE>

Description

SPECIFICATION Electric lamp This invention relates to an electric lamp and is primarily concerned with a lamp of the kind used at the site of road workings or other temporary hazards to provide a visible warning of the temporary hazard.

According to the invention there is provided an electric lamp comprising a battery, an electrically energisable light source, a pair of electrical contacts through which current flows between the battery and the light source when the lamp is in use, and a spacer interposed between the contacts to maintain them apart until the light source is required to be energised, the spacer being movable relative to the contacts to permit the contacts to engage each other and thereby complete the electrical circuit from the battery through the light source.

The spacer may be removable from the lamp when the light source is required to be energised.

With this arrangement, the lamp cannot readily be turned off once it has been turned on. It will be understood that the battery may comprise a single cell or a plurality of cells.

Two examples of lamp embodying the invention will now be desribed, with reference to the accompanying drawings, wherein: FIGURE 1 shows a perspective view of the lamp, certain parts being broken away; FIGURE 2 shows a cross-section of the lamp in a vertical plane; and FIGURE 3 shows a fragmentary cross-section of a modified lamp viewed in the direction of arrow Ill on Figure 1.

The lamp shown in Figures 1 and 2 comprises a battery 10 having a case within which are disposed a plurality of electrical cells. The battery has two terminals, 11 and 12 respectively projecting upwardly from an upper wall of the battery case, the terminal 11 being disposed at the centre of the upper wall and the terminal 12 being situated near to a corner of the upper wall.

As viewed in plan, the battery has a square shape.

The lamp further comprises a housing 13 comprising an upper wall 14 from which there depend four side walls 1 5 which are an interference fit on the side walls of the battery 1 0.

The upper wall 14 is spaced somewhat from the upper wall of the battery and there may be provided in the housing one or more abutments 1 6 to limit approach of the upper wall 14 to the battery. There is secured on the upper surface of the upper wall 14 a bulb carrier 1 7 which is formed of electrically conductive material and which has an aperture in which the bulb 18 can be screwed in the usual way. In the centre of the upper wall 14 there is provided an electrical conductor 1 9 which establishes electrical contact between the central terminal 11 of the battery and a central terminal of the bulb 18. In the assembled lamp, the centre terminal of the bulb is permanently in electrical contact with the centre terminal 11.

There is secured to the underside of the upper wall 14 an annular contact 20 of electrically conductive material which is connected with the bulb carrier 1 7 by an electrically conductive rivet 21. The contact 20 passes directly over the battery terminal 12 and is engaged thereby when the bulb 18 is energised from the battery 10. It will be noted that both of the terminals 11 and 12 are resiliently deformable and, in the particular example illustrated, have the form of a coiled compression spring which, when unstressed, has a length substantially exceeding the separation between the battery 10 and the upper wall 14.

The lamp further comprises a spacer 22 in the form of a strip of electrically insulating material, one end part of which is interposed between the battery terminal 12 and the contact 20 to maintain these apart until the bulb 18 is required to be energised. A further end part 23 of the strip 22 protrudes from the housing 1 3 through an aperture therein. The strip 22 is preferably formed of a flexible plastics material, preferably resiliently flexible, so that the protruding end part 23 can be folded against the side wall of the housing 13 for storage and packing of the lamp. When the lamp is removed from its packing, the end part 23 of the strip will tend to spring away from the housing so that it can readily be grasped.

The contact 20 and the battery terminal 12 (which forms the other one of the pair of contacts hereinbefore mentioned) are both engaged with the spacer strip 22 under pressure determined by the degree of compression of the spring contact 12. There is substantial friction between the spacer strip on the one hand and the electrical contacts on the other hand, this friction restraining movement of the spacer strip relative to the contacts. This friction can readily be overcome by a user whoe grasps the protruding end part 23 of the strip and withdraws the strip from the housing.

It will be understood that the strip cannot readily be re-inserted to switch the lamp off. Normally, the bulb 18 will remain energised until the battery 10 is exhausted.

There is provided in a side wall of the housing 13 a further opening 24 which is adjacent to the battery terminal 12. Through this opening, there can be inserted an instrument 25 having an electrically conductive, bifurcated end portion by means of which the spacer strip 22 can be bridged temporarily to provide an electrically conductive path from the terminal 1 2 to the contact 20 to enable operation of the lamp to be tested.

The lamp is conveniently assembled with the housing 1 3 inverted after the contact 20 and bulb carrier 1 7 have been secured to the upper wall 14. The spacer strip 22 is introduced through its opening in the housing to lie on the contact 20.

The battery 10 is then applied to the housing 13 so that the terminal 12 bears on the strip 22. The assembled housing and battery can then be turned over and the bulb screwed into the carrier 1 7.

Finally, a light-transmitting cover 26 is applied to the housing to enclose the bulb and bulb carrier.

Certain parts of the lamp shown in Figure 3 correspond to parts of the lamp already described with reference to Figures 1 and 2. Such corresponding parts are indicated in Figure 3 by like reference numerals with the prefix 1. The preceding description is deemed to apply to the lamp shown in Figure 3, except for the differences hereinafter mentioned.

The terminal 112 of the battery 110 has the form of a flat plate secured in face-to-face relation with the upper wall of the battery case. For cooperation with this terminal, there is provided a contact 127 in the form of a leaf spring having one limb which is secured to the underside of the wall 114 of the housing 11 3 by a rivet which establishes an electrically conductive path between the leaf spring 127 and the bulb carrier 117.

The spacer strip 1 22 is interposed between the leaf spring 1 27 and the battery terminal 112 to maintain these contacts apart when the bulb is not required to be energised. The spacer strip protrudes to the outside of the housing 113 through an aperture so that the protruding portion can be grasped by a user to enable the spacer strip to be withdrawn from the housing and to permit the leaf spring 127 to flex downwardly to engage the battery terminal 11 2, thereby completing the circuit from the battery to the bulb 11 8. Spring 127 is formed to engage the spacer strip 122 or the battery terminal 112 under pressure.

The spacer strip 122 is somewhat stiffer than is the spacer strip 22, although the end portion of the spacer strip 1 22 which protrudes from the housing 113 can be bent to lie against the side wall of the housing for storage and packaging of the lamp. Typically, the spacer strip 122 is formed of a single, solid piece of polypropylene having a thickness of approximately 2 mm. The leaf spring 127 is shaped to provide a tapered gap 128 leading to a nip between the leaf spring and the battery terminal 112 when the bulb 118 is energised. The spacer strip 112 can be inserted through the aperture in the housing into this gap to separate the leaf spring from the battery terminal and thus open the circuit from the battery to the bulb. The spacer strip can be replaced in the position in which it was placed during manufacture of the lamp.

Claims (14)

1. An electric lamp comprising a battery, an electrically energisable light source, a pair of electrical contacts through which current flows between the battery and the light source when the lamp is in use, and a spacer interposed between the contacts to maintain them apart until the light source is required to be energised, the spacer being movable relative to the contacts to permit the circuit from the battery through the light source to be completed.

2. A lamp according to Claim 1 wherein at least one of said contacts is biased towards the other.

3. A lamp according to Claim 2 wherein said one contact is a spring.

4. A lamp according to any preceding claim wherein the spacer is formed of electrically insulating material.

5. A lamp according to Claim 4 wherein the spacer is engaged with both contacts.

6. A lamp according to any preceding claim further comprising a housing containing the contacts and the interposed part of the spacer, and wherein a further part of the spacer protrudes from the housing to be accessible at the outside of the housing.

7. A lamp according to Claim 6 wherein the spacer is in the form of a flat strip.

8. A lamp according to Claim 7 wherein the spacer is flexible.

9. A lamp according to any one of Claims 6 to 8 wherein there is provided in the housing an opening through which an electrically conductive instrument can be inserted to engage both contacts.

10. The combination comprising a lamp according to Claim 9 and an electrically conductive instrument adapted for insertion through the opening to engage both of said contacts to provide an elecrically conductive path between them.

11. A lamp according to any one of Claims 6 to 8 wherein the spacer is sufficiently stiff to be pushed between said contacts to separate them.

12. A lamp according to Claim 11 wherein said contacts are so arranged that, when the spacer is removed from between them, they define a tapered gap leading to a position at which the contacts are engaged with each other.

13. A lamp according to Claim 12 wherein one of said contacts is a leaf spring.

14. A lamp substantially as herein described with reference to and as shown in Figures 1 and 2 of the accompanying drawings.

1 5. A lamp according to Claim 14 modified substantially as herein described with reference to and as shown in Figure 3 of the accompanying drawings.

1 6. Any novel feature or novel combination of features disclosed herein or in the accompanying drawings.