It is known to provide lights with an adjustable rheostat, adjustable by the user to select a predetermined intensity of light emitted by the unit. One known form of such a light comprises a"standard"lamp or a table lamp which are freestanding and can be moved to be desired position. Typically however, such lights must be connected by a cable to the main electricity supply. Such lights are therefore not completely mobile.

Hand torches are completely mobile and it is known to provide such torches with a series of coloured glass shields which may be moved over the light output to provide different coloured light outputs. However, the known systems cannot change the intensity or colour of the light emitted without manual intervention.

The present invention seeks to provide a light unit which is adapted to emit light with a variable intensity, colour and/or sequence of intensity and/or colour to provide particular light effects.

According to the present invention there is provided a free-standing, mobile light unit including a light emitting element, a re-chargeable battery to power the light emitting element, and control means adapted to adjust the intensity and/or the colour of the light emitted by the element in accordance with a predetermined sequence or in response to a predetermined control signal. Preferably, the control means includes an on-off switch, which may be a tilt switch operable by tilting the light unit.

The control means may be adapted to be selectively operable to enable a selected one of a plurality of light sequences to be rendered operable. The operation of the control means and/or adjustment of the control means may be by touch sensitive means, pressure sensitive means or temperature sensitive means and may include a membrane potentiometer such as that sold under the name Spectra Symbol SOFT POT, which includes a plurality of individual switching stations each of which may initiate a particular programme for the light output.

The light unit may be generally egg-shaped and may have a flat portion at one end, which forms a base end, to bias the egg to an upright position.. The re-chargeable battery is preferably located in the egg shaped unit adjacent to the base end to provide stability and also to provide easy electrical connection to a charging unit for recharging the battery. The electrical connection may be by induction or may include a socket to enable the unit to be plugged onto the charger.

A preferred embodiment of the present invention will now be described by way of example with reference to the accompanying drawings in which:- Figure 1 shows a side view of a light unit Figure 2 shows a sectional view of Figure 1 along the line B-B, Figure 3 shows a bottom view of the unit in Figure 1, Figure 4 shows a battery charging device, Figure 5 shows a perspective view of the underside of a light unit showing an electrical connection, and Figure 6 shows a cross-section of an alternative embodiment shaped like a conventional table lamp.

Referring now to Figures 1-3, there is shown a generally egg-shaped light unit 1 having a lower opaque base part 2 and a transparent or translucent upper part 3. The upper part 3 is clipped or screwed onto the base part so that it is re-movable to gain access to the interior of the unit. The unit has a flattened base portion 4 to provide stability to the light unit to enable it to remain in an upright position. The base part 2 also contains an on-off switch 5 to enable the light to be switched on and off manually.

Figure 2 shows a cross sectional view of the light unit along the line B-B of Figure 1 and it can be seen that the light unit contains a re-chargeable battery 6 and a light emitting source 7 which is shown in the form of an RGB LED bulb capable of producing a wide range of intensity and/or colour for the light within the visible spectrum.

Referring now to Figure 4, there is shown a battery charging unit 8 in the form of a plate 9 having a plurality of recesses 10 each adapted to receive a light unit 1 for recharging purposes. The charging unit 8 is connected to a mains power supply through an electrical lead 11. Each of the recesses 10 contains an electrical connection 12 for charging the battery in a light unit located in the recess. The connection 12 may be by inductance or each recess may contain electrical pins 13 as illustrated in Figure 4. In this case, as shown in Figure 5, the light unit 1 will incorporate a socket 14 engageable with the pins 13 in the recess.

Each light unit 1 contains control means which is adapted to change the light emitted, either the intensity and/or colour of the light in accordance with a predetermined sequence or control signal. The on-off switch 5 is preferably touch- sensitive. The control means may also be selectively operable to enable a selected one of a plurality of light sequences to the selected. Operation of the control means, and the adjustability of the light may be by a temperature responsive touch sensitive control, or by a pressure sensitive control so that the control signal given to the control means varies the longer and/or harder the light unit is touched. The control may be by means of a touch-sensitive membrane potentiometer extending in a linear manner around part of the periphery of the unit and may be such as to provide an infinitely variable signal to the control or may provide a step-wise variation in the signal to enable a plurality of different programmes in the control means to be selectively triggered.

It is also intended to give each light unit a receptor, responsive either to radio signals, sound or light signals which can be, but are not essentially, emitted from other light units. In this way, the light units will have the ability to interact with each other so that, for example, a particular light frequency being emitted from one light unit may be used to trigger a particular light output of an adjacent light unit. Thus, it would be possible, for example, by arranging the units in a circle round a room or a dining table, to effect a form of Mexican wave in which the light gradually changes in sequence around the circle of lights.

It will be understood that the embodiment of light unit illustrated is by way of example only. For example, although shown as two separate parts, the transparent or translucent upper part 3 and the opaque lower part 2 the unit could be entirely of a translucent material and the degree of opacity may vary over the surface of the unit, being less translucent at its lower part for example. Also, although the light source is described as an RGB LED, it could also be a fibre optic unit which may be such that the colour emitted by the unit can be varied across the surface of the unit. The on-off switch may alternatively be a tilt switch operable by tilting the unit.

Although described as egg-shaped, it will be understood that the unit could take other forms and may be shaped to conform to any chosen object such as a 3D Trade Mark for marketing purposes, designer objects, model buildings or cars. An alternative shape is shown in Figure 6 in the form of a table lamp. Functionally, the lamp operates in the same way as the egg-shaped unit of the first embodiment. As shown, it has a base unit 4, a battery 6 and a light-emitting diode 7 as in the first embodiment. The lamp has a generally barrel-shaped main body 12 open at its supper and lower ends, which is formed of an opaque plastics material, ceramic or terra cotta which contains the functional elements just described with the light emitting diode 7 projecting above the main body 12 into a translucent shade element 13. The base unit 4 is a snap fit in the lower opening in the main body 12. The translucent shade element comprises a frusto- conical shaped body closed at its upper, smaller diameter end 14 and closed at its lower end 15 by a wall 16. The wall 16 has a central opening 17 through which the diode 7 projects, the opening defining a spigot adapted to clip onto the main body 12 to secure the shade to the main body.