This invention relates to an electric lamp, and in particular a lamp in which the light source can be a light emitting diode (LED) or other low energy source.

There are known low energy replacement lamps which include light sources such as light emitting diodes. These provide a relatively high light output, comparable to that of incandescent standard light bulbs, whilst consuming much less energy. For example, a typical incandescent bulb may produce approximately 15 lumens per watt whereas an LED replacement bulb may produce up to 100 or more lumens per watt. Low energy replacement lamps are provided with standard fittings for connecting to lamp holders designed to deal with standard incandescent bulbs, such as bayonet fittings or Edison screw (ES) fittings and may come in various shapes and sizes. Low energy replacement lamps are available to match the designs of a number of standard lamps.

A problem arises when there are special aesthetic requirements for a low energy replacement lamp. This may be the case when a chandelier is concerned. The range of low energy lamps available may not include a design that is appropriate to match the chandelier. An object of this invention is to provide a more versatile arrangement for providing low energy replacement lamps.

Viewed from one aspect of the invention, there is provided a low energy electric lamp comprising a base unit provided with electrical contacts and with means for engaging with a light fitting also having electrical contacts, whereby the base unit may interlock releasably with such a light fitting so that the electrical contacts of the base unit are engaged with the electrical contacts of the light fitting; the base unit having conductors which connect the electrical contacts to electrical socket means, and a light module comprising a low energy electrically powered source of light is connected releasably to the electrical socket means; wherein a translucent envelope surrounds the light module and is connected in a replaceable manner to the base unit by means of a grommet which surrounds part of the base unit.

For a lamp in accordance with the invention, the translucent envelope can be of any size or shape that will surround the light module and can thus be of any design that is required to meet aesthetic requirements. Envelopes can be custom made to any specification. Envelopes that are no longer required, for example because the user prefers a different design, can be replaced and then re-used. A replacement envelope can be used with the same light module. The envelope, which typically be made of glass, is sustainable and does not need to be thrown away unless it is broken. In addition, replacing the lamp with one of a different design does not require replacement of the light module, which is can be re-used.

If the light module fails it is not necessary to replace the entire lamp. The envelope can be removed, the failed light module replaced by a working module, and then the envelope replaced. In a similar manner, if it is desired to change the brightness or other parameters of the light emitted, this can be achieved by changing the light module (which can be re-used) making it unnecessary to replace the entire lamp. If the envelope is broken, it can be replaced whilst retaining the same light module.

A lamp in accordance with the invention is thus kinder to the environment as it comprises a number of different parts which can be replaced and re-used. A conventional incandescent bulb must be thrown away if any part fails.

A typical use of a lamp in accordance with the invention may be in the context of lamps for chandeliers.

The means for engaging with a light fitting may be adapted to interlock with the light fitting by means of relative rotation between the lamp and the light fitting. The means for engaging with a light fitting could be adapted to engage with a bayonet type fitting, or with an Edison screw (ES) type fitting.

In some embodiments of the invention, the electrical socket means of the base unit comprises a pair of sockets into which corresponding pins of the light module are pressed.

The light module may be in the form of an array of light emitting diodes, preferably arranged to produce an omnidirectional output, at least around the axis of the bulb, which in normal use will be vertical. One suitable bulb is the G4 omnidirectional LED lamp available from Aurora Limited of St. Albans, United Kingdom. Many other suitable LED light modules are available, with a range of connectors for e.g. G4 or G9 or other sockets in the base unit. Preferably, a low energy replacement lamp in accordance with the invention has a light module with an output of at least about 45 lumens per watt. More preferably the output may be of at least about 85 lumens per watt or at least about 100 lumens per watt. Typically the output of the lamp will be equivalent to a conventional incandescent bulb of about 25, 40, 60 or 100 watts.

The translucent envelope may be clear, i.e. fully transparent, or frosted, or of any other degree of translucence desired.

It will be appreciated that the envelope will have an opening at one end which fits around the grommet. Preferably the grommet has a chamfered profile, i.e. tapering from one edge to the other. This provides regions of varying diameter, so that envelope openings of different sizes can be accommodated.

Particularly in the context of a scenario where the bulb maybe suspended upside down, in which case the grommet fit with the envelope needs to be at it's most secure, steps may be taken to provide a better fit with the envelope. These may be combinations of a) protruding serrations or beads of rubber around the

circumference of the grommet to offer additional purchase when compressed by the envelope and/or b) an indentation or bead within the circumference of the rubber for the rounded bottom of the envelope to "pop" into the indented bead securely.

Thus , in some embodiments of the invention the outer surface of the grommet is provided with at least one protrusion to assist in gripping the envelope. The at least one protrusion may be in the form of at least one peripheral bead.

Alternatively, the at least one protrusion is in the form of at least one peripheral row of spaced protrusions. Additionally or alternatively, in some embodiments of the invention, the outer surface of the grommet is provided with a peripheral groove which receives an edge of the envelope adjacent said opening at one end. A preferred property of the rubber of the grommet is that it will be tactile. Rubber may also be used in the base unit to improve the fit of the light module's pins in the base unit. Again, this would assist with the scenario of an upside down bulb. The light module will still maintain electrical connection with the base unit and the rubber will further ensure a compression fit with the pins over and above the electrical connection.

Viewed from another aspect, the invention provides base unit for a low energy electric lamp, the base unit being provided with electrical contacts and with means for engaging with a light fitting also having electrical contacts, whereby the base unit may interlock releasably with such a light fitting so that the electrical contacts of the base unit are engaged with the electrical contacts of the light fitting; the base unit having conductors which connect the electrical contacts to electrical socket means, adapted to receive releasably a light module comprising a low energy electrically powered source of light; the base unit being provided with grommet which surrounds part of the base unit, the grommet being adapted to engage with a translucent envelope to surround the light module.

In some embodiments, the base unit is provided in combination with a light module received by the electrical socket means. In some embodiments, the base unit is connected by means of the grommet to a translucent envelope which surrounds the light module.

Another aspect of the invention extends to the lamp in combination with a lamp holder, which may be part of a chandelier having a plurality of holders, each of which is provided with a lamp as described above.

An embodiment of the invention will now be described by way of example and with reference to the accompanying drawings, in which:

Figure 1 is a side elevation of a lamp in accordance with the invention; Figure 2 is a top plan view of the base unit of the lamp; Figure 3 is a side elevation of a lamp holder for use with the lamp; Figure 4 is a side elevation of the lamp mounted in the lamp holder; and Figure 5 is a side elevation of a modified grommet.

Figure 1 shows a lamp 1 in accordance with the invention, comprising a removable and replaceable translucent envelope 2 of glass or another suitable material, and a base 3. The envelope emulates a candle type of shape. At its lower end the base unit is configured as a male bayonet fitting, with side pins 4 to engage in a bayonet light fitting and a pair of bottom contacts 5 which form an electrical contact with contacts in the fitting when the lamp is inserted and turned to latch it in place.

The upper part 6 of the base unit is provided with a pair of sockets 7, which in this case provide a G4 configuration. Conductors 8 pass from the bottom contacts 5 to the sockets 7, so as to provide an electrical connection to a pair of pins 9 on a low energy LED light module 10, which in this case is an omnidirectional module with a plurality of LEDs 1 1 .

A grommet 12 in the form of a ring of rubber, synthetic rubber or another suitable eiastomeric material is provided between the envelope 2 and the upper part 6 of the base unit. This provides a seal between the envelope and the base unit, around the entire circumference of the upper part of the base unit. The grommet both serves to isolate the space with the envelope from the environment, to prevent the ingress of moisture, dust and so forth, and to secure the envelope to the base unit by virtue of the tight fit around the envelope and around the base unit. However, additional securing means could be provided to hold the two together. The envelope 2 has an opening at its lower end which fits around the grommet. The grommet 12 has a chamfered profile, i.e. tapering from one edge to the other. This provides regions of varying diameter, so that envelope openings of different sizes can be

accommodated. Figure 3 shows a light fitting 13 for use with the lamp, which emulates a holder for a candle. There is a dish 14 and a holder portion 15. Within this holder portion 15 is a socket 16 of a female bayonet fitting, provided with contacts 17 which engage with contacts 5 when the lamp is placed in the holder and rotated so that the two parts of the bayonet fitting interlock. The contacts 17 are connected to a flex 18. In this form the holder could be used with a conventional lamp.

Figure 4 shows the lamp 1 mounted in the holder portion 15 of the light fitting 13. In this arrangement the flex 18 may be connected to a power supply, such as a DC source (say 12 volt or 24 volt) which uses a transformer and a rectifier connected to the AC mains; or another type of power supply such as an LED driver. In some alternative embodiments, a transformer or other power supply could be embedded within the lamp itself. Figure 5 shows a modified grommet 19 of rubber or another resilient material that will provide a secure fit with the envelope 2. There is a central bore 20 defined by a wall 21 which is of tapering cross section, in this case triangular, with the thinner portion at one end and the thicker portion at the other end. The central bore fits over the upper part 6 of the base unit, forming a secure fit. To improve the security of the fit with the envelope 2, the outer wall of the grommet is provided with a peripheral bead 22. As shown this is a continuous bead but this could be replaced by a series of spaced protrusions such as serrations. The bead or protrusions serve the purpose of providing additional purchase when compressed by the envelope. In this embodiment there is also provided a peripheral groove or indentation 23 in the outer wall of the grommet. This receives the edge 23 (Fig. 1 ) at the open end of the envelope 2, which forms a pop fit into this groove so as to improve the security with which the envelope is retained. The edge 23 may be rounded. Either or both of these feature may be used, and they are of particular use when the bulb is suspended upside down.