GB2093971A - Decorative attachment for electric lamps - Google Patents

Abstract

A decorative attachment for an electric lamp consists of a casing (1) made from two or more parts (8 and 9) which are assembled around the bulb by means of hooks on one part which engage a flange (26) on the other, the assembled casing being such that the bulb cannot be withdrawn from it. The casing includes inwardly directed spacers (15, 16, 24 and 25) which engage a relatively small area of the bulb and maintain a gap between the bulb and the casing. <IMAGE>

Description

SPECIFICATION Decorative attachments for electric lamps This invention relates to decorative attachments for electric lamps, and in particular to decorative attachments for electric lamps of the kind (hereinafter referred to as the kind specified) comprising a transparent or translucent bulb of generally globe-like shape containing light-producing means, such as a filament which can be heated by electricity, the lamp having a projecting neck carrying electric terminals for the light-producing means. The terminals may be mounted on or incorporated in a cap secured to the bulb. Part of the neck of the lamp may be constituted by a projecting part of the bulb.

It is usual for the bulbs of such lamps to be uncoloured and to be transparent or translucent so that in use the light from the lamp is white or approximately white. Nevertheless there is a requirement for lamps which produce light of colours other than white. Various methods have been adopted to enable lamps to produce light of colours other than white. In one method the bulbs themselves have been made of transparent or translucent coloured glass; in other methods the inside or outside surfaces of the bulbs have been lined or coated with coloured varnishes or similar coloured materials which permit light of only certain colours to pass through them. In one commonly adopted method, bulbs of clear glass are dipped in liquids which dry or set to form such coloured materials. None of those methods, however, is entirely satisfactory. The use of coloured glass is expensive.The use of varnishes and other coloured materials is also expensive, and in addition it suffers from the problem that it is difficult to provide materials which will withstand prolonged use without fading, or otherwise changing in colour, or without becoming crazed or even becoming partially or wholly detached from the bulb.

An object of the present invention is to provide means enabling at least some of those difficulties to be reduced or overcome.

While the invention provides means enabling lamps to produce light of different colours, it is not restricted to this field and may also provide decorative features of other kinds, as described in more detail below.

From one aspect the present invention comprises a decorative attachment for an electric lamp of the kind specified, which comprises a casing having at least two parts which can be assembled together around the bulb, the casing being so shaped that when it is assembled around the bulb, the bulb cannot be withdrawn or separated from it, the casing having an opening for the neck of the lamp and including inwardly directed spacing means for contact with a relatively small area of the surface of the bulb and to ensure that there is a gap or there are gaps between the bulb and the remainder of the casing.

The gap or gaps between the bulb and the casing helps or help to prevent the lamp becoming over-heated in use.

The spacing means may be integral with at least one of said parts of the casing and may comprise at least one inwardly directed projection. Alternatively the spacing means may be formed separately from said parts and may be disposed between the bulb and the parts or at least one of the parts. The spacing means may comprise resilient means such as a helical compression spring operative in use to bear on the bulb. When the spring means is separately formed from said parts it may be anchored to at least one of them. The same attachment may incorporate spacing means of both kinds.

From another aspect the present invention comprises an assembly comprising an electric lamp of the kind specified with a decorative attachment, of the kind outlined in the last preceding paragraph, assembled around it.

The neck of the lamp may lie wholly outside the casing, in which case the neck is aligned with the opening, and part of the bulb adjacent to the neck lies in the opening. Alternatively the neck of the lamp may lie wholly inside the casing, in which case that part of the casing adjacent to the opening is shaped to accommodate the neck of the lamp, and the terminals of the lamp are accessibie through the opening. In a preferred arrangement, however, the neck of the lamp projects through the opening and the terminals are disposed outside the casing.

The parts of the casing are preferably made so as to be separate from one another before assembly. Nevertheless it is within the scope of the invention to provide a casing of which the parts are formed unitarily or are linked together to permit relative movement, before they are assembled around a bulb. For example the casing could comprise two or more relatively rigid parts joined by a flexible strap or flexible straps, which might be integral with those parts, or it could comprise two or more relatively rigid parts hingedly connected together.

Preferably the casing comprises two relatively rigid parts, one of which constitutes a flared collar with said opening at its narrower end and the other of which constitutes a closure for attachment to the broader end of the collar, the arrangement being such that the casing can be assembled around a lamp of the kind specified, the maximum breadth of the bulb being greater than the minimum breadth of the opening so that the bulb cannot be passed right through the opening.

Alternatively the casing could comprise two relatively rigid parts of the same or similar shape, capable of being attached together in face-to-face relationship to form a generally globe-shaped or bulb-shaped casing with an opening for the neck of the lamp, one part of the opening being defined by one part of the casing and the other or another part of the opening defined by the other part of the casing.

The casing is preferably shaped so as to permit little or no relative movement, other than relative rotational movement, between the lamp and the assembled casing. Where resilient spacing means is provided, operative in use to bear on the bulb, the arrangement is preferably such that the spacing means engages the bulb with sufficient friction to prevent free movement of the casing relative to the lamp.

The casing may include optical deflecting means operative to act in the manner of one or more prisms and/or lenses so arranged that in use the casing appears patterned with areas of greater and lesser brightness. For example at least part of the inside surface of the casing may be formed with ribs of triangular shape in crosssection, which act like prisms. It is preferred to provide any such irregular surface features on the inside of the casing, and to arrange for the outside surface of the casing to be relatively smooth as to enable it the more readily to be kept clean.

In addition to said opening for the neck of the lamp the casing may also be provided with one or more other apertures. When a lamp with a casing is to be used out of doors, one or more drainage apertures are preferably provided to enable rain water to drain from inside the casing. The apertures may also assist in the circulation of air inside the casing.

The casing may be clear, so that it does not have a coloured appearance in use. However, at least one of the parts of the casing is preferably coloured. The parts may be of the same colour, or one or more may be uncoloured or may be of a colour different from the other or others. Where a part is coloured it is preferably made from a plastics material with colouring incorporated in it, the colouring not being applied to the surface or incorporated in only the surface layers of that part. The colouring used is preferably of a kind resistant to ultra-violet radiation.

Each part of the casing is preferably formed as a moulding of a plastic material. Acrylic materials are often suitable, as are polycarbonate materials, though the latter tend to be unnecessarily expensive.

An embodiment of the invention will now be described in more detail, by way of example, with reference to the accompanying drawings in which Figure 1 is a side view of a decorative attachment embodying the present invention and comprising a two-part casing, Figure 2 is a somewhat diagrammatic sectional view of the casing shown in Figure 1, the plane of the section including the principal axis of the casing and the outline of a lamp to which the casing is attached being shown in chain-dotted lines, Figure 3 is an axial view of a collar constituting one part of the casing shown in Figures 1 and 2, as viewed from above in said Figures, Figure 4 is an axial view of a closure constituting the other part of the casing shown in Figures 1 and 2, as viewed from below in said Figures, and Figure 5 is a scrap view of attachment means shown in Figure 1 but to a larger scale, and in relative positions assumed in the course of the assembly of the casing.

The casing, 1, that is illustrated, is intended for use with an electric lamp of a standard kind. The outline of such a lamp, 2, is shown in Figure 2.

This is a standard GLS lamp and comprises a glass bulb 3 containing light-producing means constituted by a filament (not shown). The bulb 3 is of generally globe-like shape but has a projecting portion 4, which is attached to a cap 5 carrying terminals 6 for the filament. The cap also has bayonet lugs 7 projecting from it. The portion 4 of the bulb and the cap 5 together constitute the neck of the lamp. It will be appreciated from the following description that the casing 1 could equally well be used with a lamp having a bulb of the same shape as that illustrated but a cap of the screw-threaded kind, such as an Edison screw cap, in which there is one terminal at the end of the cap and another constituted by the screwthreaded metal shell of the cap.

The casing 1 comprises two parts, 8 and 9, each made as a separate moulding of an acrylic plastics material, the mould for each moulding being a simple two-part mould, with no moving parts or inserts. Each part of the casing is transparent but contains colouring matter resistant to ultra-violet light. One part, 8, constitutes a collar and the other part, 9, a closure. The collar 8 is of flared shape and largely conforms to the shape of that part of the bulb 3 extending from near the cap 5 to the part of maximum diameter. The arrangement is such that the bulb 3 can just fit into the collar 8, with its neck projecting through the opening at the narrower end thereof. The outside surface of the collar 8 is smooth but much of the inside surface thereof is formed with ribs 10 of triangular crosssection which extend in parallel circles around the principal axis of the collar.An annular portion 11 of the collar 8, which in use extends-around the neck of the lamp, is substantially cylindrical in shape, is smooth on the outside and is also smooth and free from ribs on the inside. The outer end portion 11 constitutes the opening for the neck of the iamp, referred to above. An annular portion 12 of the collar adjacent to the broader end of the collar, however, is smooth outside but is formed internally with ribs 13, which are parallel to the principal axis of the collar. The ribs 13, like the ribs 10, are of triangular crosssection. The ribs 10 and 13 constitute optical deflecting means and act in use as prisms so that the casing appears patterned with areas of greater and lesser brightness.

The collar 8 is formed with six apertures 14 uniformly spaced around the collar and located at the boundary between the portion 12 and the adjacent portion of the collar. Six of the ribs 13 inside the portion 12 of the collar are enlarged to form spacing bars 1 5 uniformly spaced around the collar. The spacing bars 1 5 extend inwards further than do the remainder of the ribs 13. The collar 8 is also formed with four internal projections 16, which are uniformly spaced around the principal axis of the collar and are disposed adjacent to the annular portion 11 of the collar. The ends of the projections are rounded.

The rim at the broader end of the collar 8 is recessed internally to form an annular rebate.

Three hooks 1 7 are formed integrally with the collar and are disposed at uniform intervals around the rim. Each hook 1 7 is constituted by an axially extending lug 18 and a circumferentially extending finger 19. The tip of the finger 19 is chamfered, as indicated 20 in Figure 5. The outer surface of that part of the collar adjacent to the circumferentially extending portion 19 of each lug is formed with a recess 21 of rectangular shape, which is sufficiently deep to communicate with the rebate.

The closure 9 is of approximately hemispherical shape. A relatively small aperture 22 is formed at the centre of the closure. The outside surface of the closure is smooth, but the inside surface thereof is formed with annular ribs 23 similar to the ribs 10 and with axially directed ribs similar to the ribs 13. The closure is also formed internally with six spacing bars 24 similar to the spacing bars 24 and four axial projections 25 similar to the projections 1 6. An outwardly directed flange 26 is formed a short distance from the broader end of the closure. The flange is of annular shape but has three gaps 27 spaced uniformly around it. A short way to one side of each gap, the flange is formed with a radially extending rib 28.

The fact that the collar 8 and closure 9 are each made in a simple two-part mould has a considerable effect in determining the shapes of those components. In particular, as no re-entrant or overhanging parts can be moulded, it will be appreciated that the fingers 1 9 are in part formed by portions of a tool extending axially along the adjacent recesses 21.

In the installation of the casing illustrated, the lamp is first assembled with the collar, and the cap 5 is engaged with a complementary lampholder. The closure is then coupled to the collar. In coupling the closure and collar, the closure is fitted onto the collar so that the fingers 19 of the hooks pass through the gaps 27 in the flange 26, and the end portion of the closure enters the annular rebate in the collar. Relative rotation of the parts is effected to bring the chamfers 20 into contact with the adjacent ends of the flange, as shown in Figure 5. Further relative rotation tends to push the flange towards the collar, but this movement is resisted by the engagement between the ribs 28 and the end face of the collar, as illustrated.On the application of increased torque, however, the components yield resiliently and the fingers 1 9 pass beneath the adjacent end parts of the flange to retain the closure against the collar. Finally the ribs 28 snap into the adjacent ends of the recesses 21, as shown in chain-dotted lines in Figure 5, and thus prevent unintentional separation of the parts. Separation of the parts can be effected on relative rotation in the opposite direction, but a relatively high initial torque is required to cause the ribs 28 to leave the recesses 21. The hooks 1 7 and adjacent parts of the flange 26 constitute the coupling means referred to.

When the casing is assembled around the bulb of the lamp, the bulb cannot be withdrawn from it owing to the fact that the opening in the collar is too small to allow the bulb to pass right through it. The casing is so shaped as to permit little or no relative movement between the casing and the bulb other than free relative rotation. This makes it difficult or impossible for anyone to remove the lamp from its associated socket merely by manipulation of the casing; it is therefore normally necessary to remove the closure 9 before the lamp can be released from its socket.

In use this feature helps in preventing lamps being stolen, for its much more difficult to remove a lamp with a casing 1 than it is to remove a conventional coloured lamp which has no casing.

In practice it is found that the shapes of the bulbs vary slightly from lamp to lamp and that the bulbs tend to expand very slightly when heated.

The casing is preferably designed to accommodate such variations in shape and size without allowing significantly more piay between the casing and a bulb than is necessary for that purpose.

In use, only the spacing bars 1 5 and 24 and the projections 16 and 25 engage the bulb 3.

These therefore constitute the spacing means referred to. The arrangement is such that in the assembled casing each of the spacing bars 24 is disposed half way between an adjacent pair of spacing.bars 1 5. There is thus a gap between most of the surface of the bulb and the casing 1.

Air can enter and leave this gap through the opening at the narrower end of the collar 8 and through the apertures 14 and 22. Likewise, rain water entering the casing can drain from it through that opening and those apertures.

The casing may be used on a lamp used out-ofdoors and forming part of a display of coloured lights. In such displays it is common practice to run the component lamps at voltages lower than their rated voltages to ensure that the lamps have relatively long lives. For example, lamps are often paired so that the two lamps of each pair are connected in series so that each lamp runs at half the rated voltage. Practices such as this result in a reduction in the heat output of the individual lamps and a consequent reduction in the temperature of their bulbs; any rise in temperature of the bulb, in use, that might result from the presence of a casing around it, can therefore be partly or wholly offset by running the lamp at a reduced voltage.

The arrangement is preferably such that the casing does not become so hot that someone touching it is likely to be hurt or burned. The lamp in a casing may be arranged to dissipate no more than 1 5 watts, in which case the casing does not normally become too hot. Owing to the ribs in the casing acting as prisms, it is found that in use the encased bulb has an appearance that is more attractive and bright than that of a naked bulb, and that in consequence it is often acceptable to use, in place of a lamp with a naked bulb of a certain power, a lamp with an encased bulb of a lower power, without a loss of decorative effect.

It will be appreciated that the life of a casing embodying the present invention is likely to be many times that of a filament lamp, and that a lamp that has burned out can readily be replaced with a new one.

In a modification (not illustrated) of the casing that is described above and illustrated in the accompanying drawings, there is provided a helical coil spring, made from spring wire, between the casing and the bulb, the spring being co-axial with the aperture 22. The closure 9 is modified by the addition of four integral pegs, shorter than the projections 25 and disposed uniformly around the aperture 22. The pegs are a little closer to the aperture 22 than are the projections 25. One end turn of the spring is located between the pegs and is anchored in place by frictional engagement with the pegs. In use the other end turn of the spring bears on the adjacent end portion of the bulb and urges the casing into a position such that the projections 1 6 firmly engage the bulb.If desired the projections 25 may be omitted, though they may remain present so as to become operative if the spring is lost or broken.

The spring and the projections 16 engage the bulb with sufficient friction to prevent free relative movement between the casing and the bulb. This prevents any tendency there might otherwise be for the casing to rattle on the bulb in use. It is also found that when a spring is employed it may be possible to use a lamp dissipating a higher power than would otherwise be appropriate. For example, when using a spring use may be made of a 25 watt lamp instead of a 1 5 watt lamp (the lamps in each case being run at their normal voltage).

It will be appreciated that a spring or springs could equaily well be used in place of or additionally to the projections 16, in which case the spring adjacent to the aperture 22 may be present or may be omitted, as desired.

The kinds of casings described above may be modified, if desired, by the addition of integral decorative or other structures to the outside of the casings. For example, in a decorative casing made to resemble a flower, the collar and closures are preferably of different colours, and petal-like or leaf-like projections are provided around the broader end of the collar.

Another kind of casing embodying the present invention comprises two relatively rigid parts of the same or similar shape capable of being attached together in face-to-face relationship to form a generally globe-shaped or bulb-shaped casing with an opening for the neck of the lamp, one part of the opening being defined by one part of the casing and the other or another part of the opening defined by the other part of the casing. The two parts, when assembled around a lamp, may lie substantially entirely on opposite sides of a plane containing the axis of the lamp. The parts may be made as plastics mouldings and have inwardly directed spacing means similar to those described above and illustrated in the accompanying drawings. The parts may have integral coupling means enabling the parts to be releasably attached together.

Claims (21)

Claims

1. A decorative attachment for an electric lamp of the kind specified, which comprises a casing having at least two parts which can be assembled together around the bulb, the casing being so shaped that when it is assembled around the bulb, the bulb cannot be withdrawn or separated from it, the casing having an opening for the neck of the lamp and including inwardly directed spacing means for contact with a relatively small area of the surface of the bulb and te ensure that there is a gap or there are gaps between the bulb and the remainder of the casing.

2. A decorative attachment according to claim 1 in which the spacing means comprises a plurality of inwardly directed projections.

3. A decorative attachment according to either of claims 1 and 2 in which the spacing means comprises at least one projection formed integrally with at least one of said parts of the casing.

4. A decorative attachment according to any one of claims 1,2 and 3 in which the spacing means comprises spring means operative in use to bear on the bulb.

5. A decorative attachment according to claim 4 in which said spring means comprises a helical compression spring.

6. A decorative attachment according to either one of claims 4 and 5 in which the spring means is anchored to at least one of said parts.

7. A decorative attachment according to any one of the preceding claims in which the parts of the casing are made so as to be separate from one another before assembly.

8. A decorative attachment according to any one of the preceding claims in which the casing comprises two relatively rigid parts, one of which constitutes a flared collar with said opening at its narrower end and the other of which constitutes a closure for attachment to the broader end of the collar, the arrangement being such that the casing can be assembled around a lamp of the kind specified, the maximum breadth of the bulb being greater than the minimum breadth of the opening so that the bulb cannot be passed right through the opening.

9. A decorative attachment according to claim S 8 in which the collar and closure are provided with releasable means which become operative to attach the closure to the collar on relative rotation between the collar and the closure.

10. A decorative attachment according to claim 9 in which the coupling means comprise hook-like formations for engagement with retainers on relative rotation between the collar and the closure.

11. A decorative attachment according to any of claims 1 to 7 in which the casing comprises two relatively rigid parts of the same or similar shape capable of being attached together in faceto-face relationship to form a generally globeshaped or bulb-shaped casing with an opening for the neck of the lamp, one part of the opening being defined by one part of the casing and the other or another part of the opening defined by the other part of the casing.

12. A decorative attachment according to any one of the preceding claims in which the casing is so shaped as to permit little or no relative movement other than relative rotational movement, between the lamp and the assembled casing.

1 3. A decorative attachment according to any one of the preceding claims in which the casing includes optical deflecting means operative to act in the manner of one or more prisms and/or lenses so arranged that in use the casing appears patterned with areas of greater and lesser brightness.

14. A decorative attachment according to any one of the preceding claims in which at least the larger part of the outside surface of the casing is smooth.

1 5. A decorative attachment according to any one of the preceding claims in which the casing is formed or provided with one or more apertures.

1 6. A decorative attachment according to any one of the preceding claims in which the part or at least one of the parts of the casing that permits light to pass through it is coloured.

1 7. A decorative attachment according to claim 1 6 in which said part or each of said parts is made from a plastics material with colouring incorporated in it.

18. A decorative attachment according to any one of the preceding claims in which at least one part of the casing is formed as a moulding of a plastics material.

1 9. A decorative attachment for an electric lamp of the kind specified, substantially as hereinbefore described.

20. An assembly comprising an electric lamp of the kind specified with a decorative attachment in accordance with any of the preceding claims assembled around it.

21. An assembly according to claim 16 in which the neck of the lamp projects through the opening and the terminals are disposed outside the casing.