WO2002065016A1

WO2002065016A1 - Illumination device and illumination element therefor

Info

Publication number: WO2002065016A1
Application number: PCT/NL2002/000082
Authority: WO
Inventors: Ireneus Johannes Theodorus Maria Pas
Original assignee: Pas Ireneus Johannes Theodorus
Priority date: 2001-02-15
Filing date: 2002-02-05
Publication date: 2002-08-22
Also published as: AR032807A1; NL1017366C2

Abstract

The invention relates to an illumination device (1) comprising an at least partially light-transmitting, elongate hollow body (2, 3) which is filled with a light-transmitting material (4), and light sources (5) which emit inside the body, in the longitudinal direction thereof, and each interact with a reflector (6), and light-scattering means, in which device a plurality of pairs of light sources (5) and reflectors (6) are present in the hollow body, and each pair comprises a first light source and a first reflector, and a second light source and a second reflector, and the first reflector and the second reflector, when the light sources are operating, reflect light substantially in the direction of one another. The light sources preferably comprise LEDs. The reflectors preferably also comprise outer reflectors. In this way, it is possible to obtain a very versatile, low-maintenance illumination device with very homogeneous radiation of light. The invention also relates to an illumination element, comprising a light source (5), a reflector (6) and connection means (8, 9) for use in an illumination device according to the invention.

Description

Short title: Illumination device and illumination element therefor

The present invention relates to an illumination device comprising an at least partially light-transmitting, elongate hollow body which is filled with a light-transmitting material, and light sources which emit inside the body, in the longitudinal direction thereof, and each interact with a reflector, and light-scattering means.

An illumination device of this type is known from US-A- 5,799,124. This document describes an illumination system which comprises a flexible plastic tube which, at least at one end, is closed off by a plug which accommodates a light source, and which is furthermore filled with a liquid with a suitable refractive index. The light which is emitted by the light source can escape via scratches on the inner side of the tube. The device can be used, for example, for illumination of swimming pools.

The known device has the drawback that light is only introduced into the light guide at a maximum of two locations. Particularly if the light guide is of relatively great length, as is the case in swimming pool illumination, this will result in insufficient homogeneity of illumination, which is undesirable. In addition, the possibilities of illumination are limited on account of the maximum number of light sources being two. For example, it is impossible to display a light signal running in one direction.

It is an object of the present invention to overcome the above drawbacks, and to this end the invention is characterized in that a plurality of pairs of light sources and reflectors are present in the hollow body, and each pair comprises a first light source and a first reflector, and a second light source and a second reflector, and the first reflector and the second reflector, when the light sources are operating, reflect light substantially in the direction of one another. - E -

As a result of a plurality of light sources being fitted in the hollow body, which acts as a light guide, in this way, the light sources radiating towards one another, relatively homogeneous radiation of light from the light guide is already achieved. In addition, it is possible to achieve a higher mean intensity. It is also possible, by suitable actuation of the light sources, to achieve various lighting effects, such as a travelling light signal.

The present application refers at a number of points to a hollow body. However, in the illumination device which is ultimately produced, the body is no longer hollow, but rather is filled with the light-transmitting material, so that it can act as a light guide based on total internal reflection. Only during production will the illumination device temporarily exist in the form of a hollow body.

For the radiation of light, it is important to note that some of the emitted light will be able to leave the hollow body directly, since the angle of incidence is favourable therefor. The proportion of the light which, by contrast, is guided onwards through total reflection can be emitted with the aid of the light-scattering means.

In principle, the light sources and reflectors may be positioned anywhere over the length of the hollow body. Preferably, from at least one first pair of light sources and reflectors, one of the reflectors is positioned back-to-back with one of the reflectors from a second pair of light sources and reflectors. This back- to-back positioning, that is to say one reflector is positioned with its rear side against the rear side of the other, ensures that the parts of the device where inhomogeneous illumination could occur are as small as possible.

Advantageously, at least two reflectors which are positioned back-to-back form a unit. This offers the advantage that the positioning and orientation of the reflectors positioned back- to-back with respect to one another is retained, with the result that no undesirable inhomogeneity can form in the illumination. In addition, the number of components of the illumination device is limited. Nevertheless, it is possible for all the light sources and reflectors to be designed as separate components if exchangeability is of preferred importance.

The distance between two reflectors which, when the light sources are operating, reflect light substantially in the direction of one another is advantageously identical over the entire hollow body. In this way, it is possible to ensure that, when identical light sources are used, the intensity becomes as homogeneous as possible. However, it is also possible for this distance to differ in order to achieve a different intensity where desired, for example as local accent illumination.

In the light sources, light is generated by light-generating means. The design of the light sources is not particularly limited, but it is preferable for at least one of the light sources to comprise two or more light-generating means. By way of example, one of the light-generating means of a light source is a light source which can emit a particular signal. Consideration may be given to a fault signal or an emergency signal. In addition, one of the light-generating means may be emergency illumination which switches on when the power supply to the other light-generating means fails.

Advantageously, each of the light sources comprises two or more light-generating means. In this way, it becomes possible, if one of the light-generating means of a light source fails, for this role to be taken over by one of the other light-generating means of the said light source. This ensures very reliable emission of light.

In principle, the light-generating means of a light source can be selected as desired, although it is advantageous for at least one light source to comprise at least two light-generating means which can radiate differently coloured light. In this way, it becomes possible, in the event, for example, of an emergency or a fault, for one or more light-generating means to emit a signal of a defined, different colour. It also becomes possible to - M - achieve specific light effects, such as a colour shift in the light emitted by the hollow body, which shift, if desired, can be changed by suitable actuation. It is also possible to apply specific accents.

Furthermore, it is possible to select suitable combinations of colours, in such a manner that any desired colour can be compiled from these colours . Consideration may be given, for example, to the colours red, green and blue belonging to the "RGB" system.

In principle, the type of light-generating means can be selected as desired, although it is preferable for the light-generating means to be selected from incandescent lamps, halogen incandescent lamps and light-emitting diodes (LEDs) . Light sources of this type can be of a very compact design and are therefore also suitable for sufficiently bundling the light even in a hollow body with a small cross section, with the aid of a suitable reflector. In addition, these light sources can be dimmed, so that in the case of the (halogen) incandescent lamps a specific colour temperature can be set by means of dimming. This offers particular advantages when adapting the light emitted by the illumination device to the desired atmosphere and ambience. Nevertheless, it would also be possible to use other light sources, such as diode lasers, or optical fibres which are introduced into the hollow body and lit up from the outside.

It is particularly advantageous for all the light-generating means to be LEDs. Since LEDs have a very long service life, a virtually constant brightness during their service life and a high efficiency, and therefore a relatively low emission of heat, LEDs are eminently suitable for illumination devices for use outdoors, at locations which are difficult to gain access to, etc. It is also possible, when using LEDs, for them to be cast substantially permanently into the hollow body by selecting a curable resin as light-transmitting material and by curing the resin after the light sources have been fitted. In this way, a very strong illumination device which requires little maintenance is obtained. There are also no particular limitations when light-emitting diodes are selected as light-generating means. However, it is preferable for the light-generating means to be selected from multicolour LEDs. These LEDs can emit two different colours of light depending on the power supply voltage. In this way, the possibility of two colours of light being emitted is created within a very small space with the aid of only one light- generating means and one associated reflector.

It is particularly advantageous for the LED crystals to be, at least in part, directly surrounded by the light-transmitting material. This means that the LED crystals themselves, and therefore the heat-generating components, are in contact, at least in part, and preferably substantially completely, with the light-transmitting material. This allows good dissipation of heat from the LED crystals to the environment of the illumination device, which the applicant has been able to prove in tests, and means that a lower operating temperature of the LEDs is achieved than when the LED is operated in air or in a separately shielded housing, as is generally the case for LEDs. Since the service life of LEDs increases at a lower operating temperature, in this way it is possible to extend the service life still further. In this respect, it is also advantageous if the light-transmitting material can circulate past the LED crystals, for example by pumping.

In a particular embodiment of the illumination device according to the invention, at least one reflector has a cross-sectional area which is smaller than the cross-sectional area of the interior of the hollow body at the location of the said reflector. In this way, it becomes possible for light which is emitted by a different light source towards the abovementioned reflector to pass the latter. In this way, any shadow from the reflector on the hollow body is greatly reduced, and in this way the homogeneity of the emitted light is greatly improved. A further advantage is that, if the light-transmitting material with which the hollow body is filled is a liquid, the latter can flow through the entire hollow body, past the reflectors and - fa - light sources, in order to provide cooling. Nevertheless, it is also possible to fill the entire cross section of the interior of the hollow body with the reflector. This may be advantageous, for example, if use is made of relatively wide light sources which need a relatively large reflector for sufficient bundling of the light.

The external shape of the reflectors is not particularly limited, although advantageously at least one reflector comprises an outer side, remote from the associated light source, which can reflect light originating from one or more of the other light sources in a direction in which the light source belonging to the said reflector does not emit any light. This means that a reflector of this type can reflect light in the direction in which the reflector itself throws a shadow with respect to the light source associated with the said reflector. This results in even more homogeneous emission of light from the illumination device.

The reflector may, for example, be designed as a truncated cone, in which case the apex angle associated with the cone is selected in such a way that the shadow is substantially completely illuminated by light which is incident on the reflector outer side, and in which case there is a recess in the truncated surface, in the form of a second reflection surface in which the associated light source is accommodated. This second reflection surface is generally in the form of a paraboloid, with the light source positioned in or close to the focal point of the paraboloid. However, any other form of the second reflection surface is also possible, in which case the light beam which is emitted by the combination of light source and reflector has a maximum angle which is such that the emitted light can be guided substantially by the light-transmitting material and the hollow body. The higher the refractive index of the light-transmitting material and/or the hollow body compared to that of air, the wider the light beam can be, in principle.

In a preferred embodiment of the illumination device according to the invention, the hollow body comprises diffuser means over at least part of its periphery. These diffuser means can be used to almost completely eliminate any residual inhomogeneity in the emitted light. Therefore, what remains is light which is emitted uniformly and will be equally visible from all sides. In principle, the diffuser means may extend over the entire periphery of the hollow body, although this is not necessary. If, for example, the illumination device is arranged on a wall of, for example, a building, it is possible to opt for that part of the hollow body which faces toward the wall not to be provided with diffuser means. In this case, it is possible, for example, for the light-scattering means to be arranged on that part of the hollow body which faces towards the wall, which means are able to ensure that light which is passed through the hollow body can still leave the hollow body via total reflection. These light-scattering means comprise, for example, uneven sections on the inner surface of the hollow body, including scratches or pits. In addition, it is possible for the inner surface of the hollow body to be coated with reflective material, in the form of, for example, powder, crystals or ribs. These reflect the light impinging on them at an angle which is such that the light no longer undergoes total reflection from the hollow body. It is also possible for the inner surface of the body to be of reflective design.

The invention also relates to an illumination element, comprising a light source, a reflector and connection means, for use in an illumination device according to the invention.

The invention will be explained in more detail on the basis of the following description of the figures, with reference to the drawing, in which:

Figure 1 shows a cross section through an illumination device according to the invention,

Figure 2 shows a set of light sources and reflectors for use in the device, and - A -

Figures 3A-3C show the structure of the illumination device illustrated in Figure 1 in section on line I-I'.

In Figure 1, 1 denotes a section of an illumination device according to the invention. Diffuser cap 2 and reflector section

3 form a hollow body which is filled with a light-transmitting material 4.

Light sources, which emit light beams 7 with the aid of reflectors 6, are denoted by 5. Power supply pins, which end in a sharp point 9, are denoted by 8. The sharp point 9 sticks into core 10 of power supply cable 11. The entire assembly is accommodated in profiled section 12.

A projecting section of diffuser cap 2, which fits into a recess 14 in a diffuser cap 2' of an adjoining illumination device 1', is denoted by 13.

Diffuser cap 2 is produced from a light-transmitting material, for example a light-transmitting plastic. Other materials, such as glass or quartz, are also possible. It is preferable for the plastic selected to have a high impact toughness and/or to be flexible. The diffuser cap 2 comprises diffuser means which are not indicated in more detail. These diffuser means ensure diffused radiation of the light incident on the inner side thereof. Diffuser means of this type may comprise, for example, a surface roughness or cast-in light-scattering materials.

On the open side of the diffuser cap 2, the latter is closed off by a reflector section 3. Together, the diffuser cap 2 and the reflector section 3 form a hollow body which is substantially round in cross section. In principle, other cross-sectional shapes are possible, for example the shape of an ellipse, oval or an undulating form. However, a round cross section is eminently suitable for an illumination device which radiates as homogeneously as possible in as many directions as possible. In principle, the hollow body could also, for example, be extruded as a single piece from a profiled section, but this may cause difficulties when installing the light sources. - 1 -

The reflector section 3 may be made from the same material as the diffuser cap 2, with the exception of the diffuser means. However, it may also be made from a material with lower optical properties or even from an opaque material. The reflector section 3 can then be provided, on the inner side, with reflection means (not indicated in more detail) . These reflection means are able to provide that light which impinges thereon is reflected at a different angle with respect to the longitudinal axis of the illumination device 1, so that this reflected light will no longer be completely reflected and can leave the illumination device 1. The reflection means may, for example, comprise a scattered light reflector, consisting, for example, of titanium dioxide powder. However, it is also possible for the surface to be of specular design, for example by sputtering on aluminium. As a result, a smaller proportion of the incident light is reflected at the correct angle, but the effective length of the illumination device 1 which can be illuminated by the light beam in question increases.

The light-transmitting material 4 with which the hollow body is filled may be of a wide range of types. It may substantially comprise water, optionally with additives, or another liquid. A clear resin, for example a bioresin, which is very light-stable, can also be selected. If desired, the selected liquid can be gelated, or the selected resin can be cured. This reduces the risk of leaks. In the case of curable resins, the curing also makes it possible to increase the overall strength.

In principle, the hollow body of the illumination device 1 according to the invention is closed off by means of a transverse wall (not shown) . Particularly in the case of cured resins, however, it is possible to leave the hollow body open or even for the diffuser means and the reflection means described above to be fitted directly in the resin, so that in principle the component parts of the hollow body, namely diffuser cap 2 and reflector section 3, can be removed. In this case, what remains is a resin body in which the light sources are accommodated. - ID -

Light sources 5 are compact light sources which emit a light beam 7. This beam 7 in part comprises directly radiated light and in part comprises light reflected via reflector 6. In principle, in each case pairs of light sources and reflectors of this type are incorporated in the illumination device 1, shining towards one another at a defined distance from one another.

The power is supplied to the light sources 5 via power supply pins 8, sharp points 9 of which project into the cores 10 of a power supply cable 11. The power supply cable 11 has a number of cores 10 which corresponds to the number of power supply pins 8 of the light sources 5. Naturally, the number of cores 10 is at least two, but this number may be supplemented by one or more additional cores. This may, for example, be an earth line or a data line. Control signals which are able to control the light source can be transmitted via the data line. If desired, this can take place with the aid of cast-in control means, such as a chip (not shown) .

The power supply cable 11 is attached to the supporting profiled section 12, for example in a longitudinal groove, with the aid of an adhesive. The adhesive is, for example, double-sided adhesive tape or a glue. The longitudinal groove in the supporting profiled section 12 has to be carefully dimensioned, in such a manner that the cores 10 of the power supply cable 11 always adopt the same position. In this way, the sharp points 9 of the power supply pins 8, by simple positioning, can penetrate the cores 10 of the power supply cable 11 in order in this way to produce an electrical connection. Nevertheless, other electrical connections are also possible, for example soldering or connectors .

The supporting profiled section 12 serves to accommodate the abovementioned components and to secure the illumination device as a whole to a support, for example a wall or other object which is to be illuminated. The supporting profiled section 12 may be made from any suitable material, but is preferably inert, for example glass-reinforced polyester, with the result that there can be no stress corrosion with respect to the support on which the illumination device is mounted.

The supporting profiled section 12 is preferably shaped in such a manner that the components which are to be accommodated, in particular reflector section 3 and diffuser cap 2, can be accommodated therein under a certain stress. To this end, the supporting profiled section 12 may be provided with a recess with internal dimensions which are substantially equal to or slightly smaller than the external dimensions of, in particular, the reflector section 3.

The projecting section 13 fits into a recess 14 of an adjacent illumination device 1 ' . This ensures a reliable coupling which is sealed against dirt and water between adjacent illumination devices. By way of example, the projecting section 13 is an encircling lip. However, other shapes are also possible.

If desired, the size of the illumination device can be tailored to each specific application. However, by creating a number of different standard dimensions, it is possible to create a very wide range of overall lengths for combined illumination devices. For example, consideration may be given to a set of standard dimensions which are comparable to a system of coins, in which any desired length can be made up from a very small number of smaller units .

Figure 2 shows a combination of two light sources 5 with the associated reflector 6. In this figure, a light source is denoted overall by 5. This light source 5 comprises two light- generating means 15 and 16. These means radiate light which is partially reflected by inner reflector 17 of reflector 6. Reflector 6 also comprises an outer reflector 18, on the outer side which is remote from light source 5.

Light source 5 is powered by means of power supply wire 19, which is connected to power supply pin 9 which ends in a sharp point 9. - IB -

Light source 5 may comprise one or more light-generating means 15, 16. These may be any desired light sources, but are preferably compact light sources. By way of example, they are small incandescent lamps, preferably low-voltage incandescent lamps, or halogen incandescent lamps. They are advantageously halogen incandescent lamps with a compact spiral filament.

Another possible light source is formed by light-emitting diodes (LEDs) . In many cases, these light sources are preferred, on account of their very long service life and high efficiency, so that relatively little heat is evolved. Moreover, they are relatively unsusceptible to damage, the brightness does not deteriorate (greatly) during the service life, and they operate on a low voltage. The choice of LEDs is not particularly limited, and it is possible, for example, to make use of standard LEDs, but also of what are known as "barracuda" or "ultrabright" LEDs. These offer a very high brightness while still having compact dimensions.

In the light source 5 illustrated in Figure 2, there are two light-generating means 15 and 16. These may, for example, be two halogen incandescent lamps of equal or different power. By way of example, one of the two light-generating means serves as a reserve light-generating means. It is also possible, in this way, to have available three different luminous intensities, namely the luminous intensity of the first halogen incandescent lamp, that of the second, and that of the combination of the two halogen incandescent lamps.

It is also possible to combine a (halogen) incandescent lamp with, for example, an LED. It is thus possible, for example, to provide the incandescent lamp light with a defined additional colour impression or to indicate a particular signal.

In addition, it is possible to use a combination of two or more different LEDs. This may, for example, be a combination of red and green, but also, for example, a combination of red, green and blue. With this latter combination, it is possible to compile any desired light colour using the so-called "RGB" system. For this purpose, the light-generating means (LEDs) have to be controlled with the aid of suitable control means. These may be cast into the illumination device 1, but it is also possible to transmit a suitable signal from external control means by means of the power supply pins 8 and the power supply cable 11. The control means may, for example, switch on or off a desired light-generating means or may dim this means. This dimming may take place, for example, with the aid of a suitably selected power supply voltage, for example for (halogen) incandescent lamps. It is also possible, when using two-colour LEDs, to select a colour by means of a suitably selected power supply voltage.

Desired light effects can be achieved by switching light sources 5 on and off in a controlled way. By way of example, it is possible to produce travelling light spots by switching the adjacent light sources on and off again with a set time delay.

With this means of control, it is advantageous for the so-called address of each light source in principle to be known, so that the control means can automatically transmit the appropriate control signals. In addition, it is also possible for the control means to establish whether a light source is faulty or in some other way failing to operate correctly. This offers certain advantages in terms of maintenance of the illumination device.

The light source 5 receives the power and the control signals via supply conductor wire 19 and power supply pin 8, which can penetrate into a core 10 of the power supply wire 11 with the aid of its sharp point 9. For this purpose, correct positioning of the power supply pins 8 with respect to the power supply cable 11 is to be maintained during installation. It is advantageous for the sharp points 9 to prick into the (combined) cores of power supply cable 11 in such a manner that the sharp points 9 come to be under stress between the constituent copper filaments of each separate core 10. This ensures reliable electrical connection. - m -

The outer reflector 18 forms a reflector for the light which originates from other light sources of the illumination device 1. For this purpose, the outer reflector 18 is generally in the shape of part of a cone, with the result that light which is incident thereon is reflected in a direction which is directed away from the supporting profiled section 12. The angle which the outer reflector 18 should form with the longitudinal axis of the illumination device 1 is dependent, inter alia, on the beam spreading of the light beams 7, on the distance between the light sources 5 and on the internal diameter of the light- transmitting material 4. The person skilled in the art will know how to set the most appropriate angle. The outer reflector 18 may be truncated on the side of the supporting profiled section 12, since there is often no need for any light to be transmitted in this direction.

By selecting the cross-sectional surface area of the reflector 6 to be smaller than the cross-sectional surface area of the light-transmitting material 4, it is possible for light which originates from adjacent light sources 5 to pass the reflector 6 and thus contribute to reducing the shadow from the said reflector 6.

In principle, the external diameter of the illumination device 1 may be of any desired size. Preferably however, it will not be selected to be excessively great and, for example, be between 5 and 50 mm. This dimension is dependent to some extent on the light sources used and the desired homogeneity. In the case of LEDs with a higher brightness, which often have a larger diameter, the overall external diameter will also increase. In principle, it is also possible to choose, for the light sources 5, light-conducting fibres which are cast into the light- transmitting material 4. This allows an extremely small diameter to be achieved for the illumination device 1, for example of only a few millimetres.

One possibility of installing a compact light source which does not require a dedicated reflector is a solid-state laser. This offers a very compact light-emitting surface and, moreover, by - IS - its very nature, a beam which is so narrow that it can be guided by the light-conducting properties of the illumination device 1. It will be possible to use this light source in particular applications .

Figures 3A-3C diagrammatically depict the structure of an illumination device 1 according to the invention. Identical reference numerals denote corresponding components from previous figures .

In principle, it will be possible, for example, for an illumination device 1 according to the invention to be constructed as follows. A reflector 6 in which a light source 5 is accommodated and which has power supply pins 8 with sharp points 9 projecting from it pricks into a reflector section 3, in such a manner that the power supply pins 8 project through the reflector section 3. Then, diffuser cap 2 is fitted by being pushed over the reflector section 3. The hollow body which then forms is closed off on one side and is then filled with diagrammatically indicated light-transmitting material 4.

The assembly formed in this way is fixed to supporting profiled section 12, in such a manner that reflector section 3 drops into a recess in the supporting profiled section 12 and that the sharp points 9 of the power supply pins 8 prick into the cores 10 of the power supply cable 11, producing an electrical connection.

The illumination device 1 formed in this way can be fixed to any desired base by means of suitable attachment means.

If a light source is defective, it can easily be removed and, if necessary, replaced if the light-transmitting material is still liquid. To do this, it is merely necessary for the combination of light source 5 and reflector 6 to be pulled out of the reflector section 3 and for a new combination to be fitted.

The illumination device 1 may be rigid or flexible. In principle, the homogeneity of the light which is emitted will - lb - not be lost with a curved illumination device 1, since in principle the light conduction in the light-transmitting material 4 means that the same optical properties are retained throughout. Naturally, this only applies up to certain maximum radii of curvature, which are determined by the refractive index of the light-transmitting material 4 and the diffuser cap 2.

To achieve even greater homogeneity of the light which is emitted, it is possible to choose to remove the diffuser means from the diffuser cap 2, so that the latter becomes clear and, in principle, a component of the light guide, and then to fit separate diffuser means around the illumination device 1, preferably with an air gap between the two components. In this way, the function of the light guide of guiding the light via total internal reflection and the function of the diffuser means are separated, so that each can be optimized independently.

Claims

1. Illumination device (1) comprising an at least partially light-transmitting, elongate hollow body (2, 3) which is filled with a light-transmitting material (4) , and light sources (5) which emit inside the body, in the longitudinal direction thereof, and each interact with a reflector (6), and light- scattering means, characterized in that a plurality of pairs of light sources (5) and reflectors (6) are present in the hollow body, and each pair comprises a first light source and a first reflector, and a second light source and a second reflector, and the first reflector and the second reflector, when the light sources are operating, reflect light substantially in the direction of one another.

2. Illumination device according to claim 1, characterized in that, of at least a first pair of light sources (5) and reflectors (6), one of the reflectors is positioned back-to-back with one of the reflectors belonging to a second pair of light sources and reflectors.

3. Illumination device according to claim 2, characterized in that at least two reflectors (6), which are positioned back-to- back, form a unit.

4. Illumination device according to one or more of the preceding claims, characterized in that the distance between two reflectors (6) which, when the light sources (5) are operating, substantially reflect light in the direction of one another, is identical over the entire hollow body (2, 3) .

5. Illumination device according to one or more of the preceding claims, characterized in that at least one of the light sources (5) comprises two or more light-generating means (15, 16) .

6. Illumination device according to claim 5, characterized in that at least one light source (5) comprises at least two light- - Ifl - generating means (15, 16) which are able to emit differently coloured light.

7. Illumination device according to one or more of the preceding claims, characterized in that the light-generating means (15, 16) are selected from incandescent lamps, halogen incandescent lamps and light-emitting diodes.

8. Illumination device according to one or more of the preceding claims, characterized in that the light-generating means (15, 16) are selected from multicolour LEDs.

9. Illumination device according to claim 7 or 8, characterized in that the LED crystals are, at least in part, directly surrounded by the light-transmitting material (4) .

10. Illumination device according to one or more of the preceding claims, characterized in that at least one reflector

(6) has a cross-sectional surface area which is smaller than the cross-sectional surface area of the interior of the hollow body (2, 3) at the location of the said reflector (6) .

11. Illumination device according to one or more of the preceding claims, characterized in that at least one reflector (6) comprises an outer side (18) , remote from the associated light source (5) , which can reflect light originating from one or more of the other light sources in a direction in which the light source (5) belonging to the said reflector (6) does not emit any light.

12. Illumination device according to one or more of the preceding claims, characterized in that the hollow body (2, 3) comprises diffuser means over at least part of the periphery.

13. Illumination element, comprising at least one light source (5) , at least one reflector (6) and connection means (8, 9) , for use in an illumination device according to one of claims 1-12.