Patent Description:
Currently, there is a high interest in bringing the positive aspects of natural light into an office, retail or home environment. Positive aspects of natural light, such as outdoor light or sun light, are e.g. dappled light created by sunlight shining through the leaves of trees or the reflected light from a water surface on the wall of a house. These dynamic light effects can be applied indoors to create a more attractive, lively atmosphere.

A known way to apply dynamic lighting is to project specific content on a wall. The projection of visual content on a wall has been investigated for at least a century. A relatively new way of projection is the use of ultra-short throw (UST) LCD projectors which can be used at a fairly close distance (less than <NUM>) to the wall. These projectors give a crisp image on the wall, however at a high cost. Another disadvantage is noise generated by a fan needed to cool the device.

<CIT> describes a lighting system with an array of lighting elements which provide light in different directions. The intensity of the lighting elements is controlled by means of a controller in dependence on a time-varying parameter related to at least one of a position of a light emitting or light reflecting body, and an intensity, color or color temperature of the light emitted or reflected by the body, such that the system can simulate directional sunlight.

It is thus desired to provide a light emitting device with which the above-mentioned disadvantages are reduced or even overcome entirely.

It is an object of the present invention to provide a light emitting device of the type with which natural dynamic lighting effects may be created, which light emitting device is cheap to produce and which do not produce noise when in operation.

It is a further object of the present invention to provide such a light emitting device which may be used at a fairly close distance to a surface to be illuminated, and which is capable of providing a high quality image on the surface to be illuminated.

According to a first aspect of the invention, these and other objects are achieved by means of a light emitting device comprising at least one cluster of light sources and lenses, the at least one cluster comprising at least a first light source and a second light source, the first light source and the second light source being adapted for, in operation, emitting first respectively second light, at least one first lens associated with the first light source, and at least one second lens associated with the second light source, where the first lens is configured to create a first illuminance pattern in a plane P and the second lens is configured to create a second illuminance pattern in the plane P, where the first light source and the first lens and the second light source and the second lens, respectively, are arranged in a predefined distance D from the plane P, the predefined distance D being measured in a direction extending perpendicular to the plane P, where the first light source and the first lens are arranged such that during operation an average emission direction of the first light is along a first axis, and the second light source and the second lens are arranged such that during operation an average emission direction of the second light is along a second axis, where the first light source and the first lens and the second light source and the second lens, respectively, are oriented such that the first axis and the second axis extend at an angle φ with a plane H extending in parallel with and in the predefined distance D from the plane P and that the first axis and the second axis intersect at or in the plane P, wherein the first light source and the first lens and the second light source and the second lens, respectively, are further arranged and on a straight line extending in parallel with the plane P and perpendicular to the direction in which the distance D is measured, wherein the first lens and the second lens are freeform lenses, and wherein the first illuminance pattern and the second illuminance pattern are mutually different illuminance patterns, each illuminance pattern comprising at least three first and at least three second areas, wherein the first areas have a first color and the second areas have a second color different from the first color and/or the first areas comprise a brightest area having a brightness Bb and the second areas are dark areas of a brightness Bd, and wherein Bd <= <NUM> * Bb, preferably Bd <= <NUM> * Bb, such as Bd <= <NUM> * Bb. The plurality of first areas is at least three, but preferably is more than three, such as four, five, ten, or more than twenty. The plurality of second areas is at least three, but preferably is more than three such as four, five, ten, or more than twenty. First and second color are to be understood as also comprising first and second color temperature and correllated color temperature. The average emission direction of a (first and second) light beam is to be understood as the direction towards the center of the whole area, comprising both first and second areas, illuminated by said light beam.

Thereby, and in particular by providing that the first lens is configured to create a first illuminance pattern in a plane P and the second lens is configured to create a second illuminance pattern in the plane P, as well as by providing that the first light source and the first lens and the second light source and the second lens, respectively, are arranged as described above, a light emitting device of the type with which natural dynamic lighting effects of a high quality as perceived by a viewer may be created, which light emitting device is structurally extremely simple and comprises very few components as compared to the prior art solutions. Such a light emitting device is cheap to produce and further does not produce noise when in operation.

The light emitting device could have the feature that each illuminance pattern comprises at least one first area surrounded by at least three second areas and at least one second area surrounded by at least three first areas. Thus an illuminance pattern with an acceptable, minimal degree of variation in illuminace is created.

Furthermore, and in particular by providing that the first light source and the first lens and the second light source and the second lens, respectively, are arranged in the distance D, and that the first axis and the second axis extend at an angle φ, as described above, it is enabled that such a light emitting device may be used at a fairly close distance to a surface to be illuminated, and is still capable of providing a high-quality image on the surface to be illuminated.

In an embodiment, the size of at least one of the first lens and the second lens is chosen in dependence of the size of a light emitting area of at least one of the first light source and the second light source.

Thereby, it becomes possible to scale the size of the optics, particularly the lenses, depending on the size of the light emitting area of the associated light source. This in turn provides for a light emitting device providing a sharper output of a particularly high quality.

In an embodiment, the angle φ is an acute angle with the plane H extending in parallel with and in the predefined distance D from the plane P.

Thereby, it is enabled that the light emitting device may be used at a particularly close distance to a surface to be illuminated and that it is still capable of providing a high-quality image on the surface to be illuminated.

In an embodiment, the predefined distance D is equal to or less than one meter.

Thereby, it becomes possible to use the light emitting surface instead of a more complex and expensive projector type, such as ultra-short throw (UST) LCD projectors.

In an embodiment, the first light source and the second light source are configured to, in operation, emitting light of mutually different colors.

Thereby a light emitting device is provided with which a wider range of visual effects may be obtained as compared to if the first light source and the second light source were configured to emit light of the same or similar color.

In an embodiment, the first light source and the second light source are configured to be tunable with respect to any one or more of color, color temperature, light intensity and light flux.

Thereby a light emitting device is provided with which a particularly wide range of visual effects may be obtained. For instance, by tuning color and flux of the first light source and the second light source, visual effects may be obtained where colors appear and disappear in time and the illuminance uniformity can vary between highly non-uniform to almost perfectly uniform. Also, by tuning color and flux as a function of time, visual effects similar to, e.g., a cloudy sky where clouds disappear and appear may be obtained.

In an embodiment, the first light source and the second light source are any one of point light sources, an LED, an LED having a light emitting area with a size of <NUM> × <NUM>, an LED having a light emitting area with a size of <NUM> x <NUM>, a plurality of LEDs, an RGB package of LEDs or an RBGW package of LEDs.

For instance, point light sources are preferred for enabling obtaining a particularly sharp pattern. Also, an LED having a square light emitting area SL with a size of <NUM> × <NUM> is preferred for enabling, for a give lens, obtaining a sharper pattern as compared to, e.g., an LED having a light emitting area with a size of <NUM> x <NUM>, which in turn nevertheless still gives an acceptably sharp pattern. A plurality of LEDs, an RGB package of LEDs or an RBGW package of LEDs are all preferred for enabling patterns composed of several - or indeed all - different colors, and thus enabling complex and highly detailed patterns.

In an embodiment, the mutually different first illuminance pattern and second illuminance pattern comprise randomly generated illuminance patterns and mutually complementary illuminance patterns.

Mutually different illuminance patterns or random illuminance patterns provide for a wide range of visual effects which may change over time. Mutually complementary illuminance patterns are particularly preferred for also enabling a constant illuminance pattern in case both the first and second light source is on. Complementary in this respect means that where a first illuminance pattern has first and second areas, the second illuminance pattern is inversed in color and/or brightness, i.e. the first areas of the first illuminance pattern that have a first color and/or are dark are areas with a second color and/or are bright areas in the second illuminance pattern, and the second areas of the first illuminance pattern that have a second color and/or are bright are areas with a first color and/or are dark areas in the second illuminance pattern.

In an embodiment, the first lens and the second lens are made of any one of optical grade PMMA and polycarbonate.

Thereby, particularly robust and durable lenses are provided for, which in turn provides for a light emitting device providing a continuously high-quality light output over a long period of time.

In an embodiment, at least a part of a light exit surface of at least one of the first lens and the second lens comprises any one of optical microstructures and an optical foil.

Thereby a light emitting device is provided with which the uniformity and smoothness of the light output is enhanced.

In an embodiment, the light emitting device further comprises at least one light mixing element arranged and configured to mix light emitted from at least one of the first light source and the second light source.

Thereby a light emitting device is provided with which the light emitted from one or both of the first light source and the second light source may be mixed in order to provide an improved uniformity of the light output.

In an embodiment, at least a part of a light exit surface of the at least one light mixing element comprises any one of optical microstructures and an optical foil.

Thereby a light emitting device is provided with which the uniformity and smoothness of the mixed light output is enhanced.

In an embodiment, the optical microstructures comprise any one or more of lenslets and surface roughnesses.

Thereby a light emitting device is provided with which an improved uniformity and smoothness of the light output may be obtained in a structurally very simple and easy to manufacture manner.

In an embodiment, the at least one cluster further comprises at least one further light source adapted for, in operation, emitting at least one further light and at least one further lens associated with the at least one further light source, where the first light source and the first lens, the second light source and the second lens and the at least one further light source and the at least one further lens, respectively, are arranged in a predefined distance D from the plane P, the predefined distance D being measured in a direction extending perpendicular to the plane P, wherein the first light source and the first lens are arranged such that during operation the average emission direction of the first light is along the first axis, and the second light source and the second lens are arranged such that during operation the average emission direction of the second light is along the second axis, and the at least one further light source and the at least one further lens are arranged such that during operation the emission direction of at least one further light is along at least one further axis, where the first light source and the first lens, the second light source and the second lens and the at least one further light source and the at least one further lens are oriented such that the first axis, the second axis and the at least one further axis extend at an angle φ with a plane H extending in parallel with and in the predefined distance D from the plane P, and that the first axis, the second axis and the at least one further axis intersect at or in the plane P, and where the first light source and the first lens, the second light source and the second lens and the at least one further light source and the at least one further lens, respectively, are further arranged and on a straight line extending in parallel with the plane P and perpendicular to the direction in which the distance D is measured.

Thereby, a light emitting device is provided which has a further degree of freedom in designing the resulting image in the plane P, and which is thus more versatile, especially in terms of use possibilities and complexity of the resulting total image in the plane P.

In an embodiment, each cluster comprises N first lenses, M second lenses and, where provided, Q further lenses, where N, M and Q each are an integer being <NUM> or more, and where N, M and Q may be the same or different.

Thereby, a light emitting device is provided which has several degrees of freedom in designing the resulting image in the plane P, and which is thus much more versatile, especially in terms of use possibilities.

In an embodiment, the first lenses, the second lenses and, where provided, the further lenses are mutually different lenses.

Thereby, a light emitting device is provided which has a further degree of freedom in designing the resulting image in the plane P, especially as two or more different images may be used to form the resulting total image in the plane P.

In an embodiment, the light emitting device further comprises at least two clusters of light sources and lenses.

In an embodiment, the light emitting device further comprises an array of clusters of light sources and lenses.

Thereby, a light emitting device is provided with which a larger area, such as a whole wall or a broad section of a wall, may be illuminated. Furthermore, such a light emitting device allows for varying the density and illuminance of the pixels forming the resulting image in the plane P with position, for instance such as to obtain a more natural transition between various settings.

In an embodiment, the two or more clusters are arranged with a pitch p seen along the straight line extending in parallel with the plane P and perpendicular to the direction in which the distance D is measured, where the pitch p is chosen to be smaller than the size in the direction of the said straight line of the areas illuminated by the respective cluster of the two or more clusters.

Thereby a seamless transition between the areas illuminated by the respective cluster of the two or more clusters is obtained.

The invention further relates to a luminaire or a lamp comprising a housing at least partly accommodating a light emitting device according to the invention.

This especially applies for the size of the lenses <NUM>-<NUM> and <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, respectively, with respect to the size of the image <NUM> and <NUM>-<NUM>, respectively, in the illustrations of <FIG> and <FIG>.

<FIG> shows a perspective view of a first embodiment of a light emitting device <NUM> according to the invention. Generally, the light emitting device <NUM> according to the invention comprises a first light source <NUM> and a first lens <NUM> as well as a second light source <NUM> and a second lens <NUM>. This applies for all embodiments of the invention.

The first light source <NUM> and the first lens <NUM> are arranged on a first axis <NUM>. The second light source <NUM> and the second lens <NUM> are arranged on a second axis <NUM>. The first axis <NUM> and the second axis <NUM> intersect at a target surface <NUM>. The target surface <NUM> is a surface which it is desired to illuminate with the light emitting device <NUM>. The target surface <NUM> may for instance be a wall (as shown on <FIG>), a ceiling or a floor.

The first light source <NUM> and the second light source <NUM> are arranged in a distance D from a plane P in which the target surface <NUM> is arranged. The distance D is measured perpendicular to the plane P, i.e. in the direction x illustrated by the coordinate system shown in <FIG>. The distance D is thus the shortest distance between the respective light source <NUM>, <NUM> and the plane P. The distance D is generally less than one meter. The first light source <NUM> and the first lens <NUM> and the second light source <NUM> and the second lens <NUM> are further arranged in a height h above a surface <NUM> extending perpendicular to the plane P. The height h is measured in the direction z illustrated by the coordinate system shown in <FIG>. For instance, in case the target surface <NUM> is a wall, the surface <NUM> may be a floor surface. The first axis <NUM> and the second axis <NUM> extend at an angle φ with a plane H extending in parallel with and in the predefined distance D from the plane P. The angle φ may be an acute angle with the plane H. The first axis <NUM> and the second axis <NUM> further intersect at or in the plane P.

The first light source <NUM> and the first lens <NUM> and the second light source <NUM> and the second lens <NUM> are further arranged on a straight line extending in the direction y illustrated by the coordinate system shown in <FIG>, and thus in parallel with the plane P and the target surface <NUM>. The first light source <NUM> and the first lens <NUM> and the second light source <NUM> and the second lens <NUM>, respectively, are more particularly arranged beside one another in the direction y. The distance or free space in the direction y between the first lens <NUM> and the second lens <NUM> is generally less than <NUM>, such as between <NUM> and <NUM>. The diameter of the first lens <NUM> and the second lens <NUM> may be between <NUM> and <NUM>.

The first light source <NUM> and the second light source <NUM> may be point light sources, or light sources having a light emitting area with, e.g., a size of <NUM> × <NUM> or <NUM> x <NUM>. The first light source <NUM> and the second light source <NUM> may be an LED or a plurality of LEDs, such as an RGB or an RBGW package of LEDs. The first light source <NUM> and the second light source <NUM> may be adapted for, in operation, emitting first light respectively second light, said first and second light being of mutually different colors.

The light emitting device <NUM> comprising at least the combination of the first light source <NUM> with the first lens <NUM> for providing first light and the combination of the second light source <NUM> with the second lens <NUM> for providing second light, said combinations together may be configured to provide any suitable or desired dynamic pattern on the target surface <NUM>, including a random pattern. The size of the first lens <NUM> and the second lens <NUM> may be chosen in dependence of the size of a light emitting area of at least one of the first light source <NUM> and the second light source <NUM>. The first lens <NUM> and the second lens <NUM> may be made of optical grade PMMA or polycarbonate or another suitable material. An example of a first lens <NUM> and a second lens <NUM> are shown in more detail in <FIG>, respectively. In this embodiment, the first lens <NUM> and the second lens <NUM> are freeform lenses and are configured to provide mutually complementary illumination patterns on the target surface <NUM>. Such complementary illumination patterns are illustrated in <FIG>, illustrating an exemplary illumination pattern of the respective lenses <NUM>, <NUM> of <FIG>. As may be seen, the lens <NUM> provides an illumination pattern (<FIG>) having some parts/areas with a first color and/or brightness A and some parts/areas with a second color and/or brightness B, while the lens <NUM> provides an identical illumination pattern (<FIG>), albeit where the parts having the color and/or brightness A in <FIG> have the color and/or brightness B and vice versa in <FIG>. Alternatively, the first lens <NUM> and the second lens <NUM> may be configured to provide mutually different or even random illumination patterns. In the <FIG> the brightness of bright areas is about six times higher than the brightness of dark areas. Also shown in <FIG> is that the illuminance pattern covers a whole illuminated area <NUM> and comprises a plurality of over ten of first areas <NUM> and a plurality of over ten of second areas <NUM>. Furthermore, there is at least one first area <NUM> surrounded by at least three second areas <NUM> and there is at least one second area <NUM> surrounded by at least three first areas <NUM>. In <FIG> the center <NUM> of the whole rectangular illuminated area <NUM> is indicated, i.e. in this case being the intersection of the two diagonals of the rectangular illuminated area <NUM>. Said center <NUM> indicates the average emission direction of a light source.

The first lens <NUM> and the second lens <NUM> comprises a light exit surface. A part or all of the light exit surface of the first lens <NUM> and the second lens <NUM> may comprise an optical element <NUM>, <NUM> (cf. <FIG>) such as optical microstructures, e.g. lenslets, surface roughnesses or the like, or an optical foil.

The light emitting device <NUM> also comprises a further (third) light source <NUM> adapted for, in operation, emitting light and a further (third) lens <NUM> associated with the further light source <NUM>. It is noted that the further light source <NUM> and the further lens <NUM> are optional features. More than one further light source and associated lens may in principle also be provided. The further light source <NUM> and the further lens <NUM> may be of any of the respective types of light sources and lenses described above. The further light source <NUM> may be of a type emitting light of a color differing from both the first light source <NUM> and the second light source <NUM> or being the same as one of the first light source <NUM> and the second light source <NUM>. The further lens <NUM> may be different from, both the first lens <NUM> and the second lens <NUM>.

The further light source <NUM> and the further lens <NUM> are arranged on a further axis <NUM>. The further light source <NUM> and the further lens <NUM> are oriented such that the further axis <NUM> intersects the first axis <NUM> and the second axis <NUM> at the target surface <NUM>. The further light source <NUM> and the further lens <NUM> are arranged in a distance D from the plane P and thus from the target surface <NUM>. The distance D is generally equal to or less than <NUM> meter. The further light source <NUM> and the further lens <NUM> are further arranged in a height h, for instance a height h above a floor surface <NUM>. The height h is typically equal to or less than <NUM>. The further axis <NUM> extends at an angle φ, such as an acute angle φ, with respect to the plane H. The further light source <NUM> and the further lens <NUM> are arranged beside the first light source <NUM> and the first lens <NUM> and the second light source <NUM> and the second lens <NUM>, respectively, in the direction y extending in parallel with the plane P and thus with target surface <NUM>. The distance or free space in the direction y between the further lens <NUM> and the first lens <NUM> and the second lens <NUM>, respectively, is generally less than <NUM>, such as between <NUM> and <NUM>. The diameter of the further lens <NUM> may be between <NUM> and <NUM>.

Turning now to <FIG>, a perspective view of a second embodiment of a light emitting device <NUM> according to the invention is shown. The light emitting device <NUM> differs from that described above in relation to <FIG> in virtue of the following features.

The light emitting device <NUM> comprises three clusters <NUM>, <NUM>, <NUM> of lenses. Each cluster <NUM>, <NUM>, and <NUM> comprises two light sources and two lenses. The first cluster <NUM> comprises a first light source <NUM> and a first lens <NUM> as well as and a second light source <NUM> and a second lens <NUM>. The second cluster <NUM> comprises a first light source <NUM> and a first lens <NUM> as well as and a second light source <NUM> and a second lens <NUM>. The third cluster <NUM> comprises a first light source <NUM> and a first lens <NUM> as well as and a second light source <NUM> and a second lens <NUM>. In comparison, the light emitting device <NUM> according to <FIG> thus comprises only one cluster <NUM>.

Generally, each cluster <NUM>, <NUM>, <NUM> is in principle identical. Generally speaking, each cluster comprises N first lenses, being lenses of a first type, and M second lenses, being lenses of a second type, where N is an integer being <NUM> or more and where M is an integer being <NUM> or more, and where N and M may be the same or different. Optionally, each cluster may further comprise Q further lenses, e.g. being lenses of a further type different from the first and second type, where Q is an integer being <NUM> or more, and where Q may be the same as or different from one or both of N and M.

The light emitting device <NUM> comprises a light mixing element <NUM> arranged and configured to mix light emitted from the first light source <NUM> of the first cluster <NUM> and a light mixing element <NUM> arranged and configured to mix light emitted from the second light source <NUM> of the first cluster. The light mixing elements <NUM>, <NUM> may be arranged between the respective light source <NUM>, <NUM> and lens <NUM>, <NUM> or (as shown on <FIG>) in front of the respective lens <NUM>, <NUM>. The light mixing elements <NUM>, <NUM> each comprise a light exit surface. A part of or all of the light exit surface one or both light mixing elements <NUM>, <NUM> may comprise optical microstructures, e.g. lenslets, surface roughnesses or the like, or an optical foil. Similar light mixing elements may be provided to the second cluster <NUM> and/or to the third cluster <NUM>.

The first light sources <NUM>, <NUM> and <NUM> and the second light sources <NUM>, <NUM> and <NUM> of each of the three clusters <NUM>, <NUM> and <NUM> are in this embodiment configured to be tunable with respect to color, color temperature, light intensity, light flux or any combination thereof. The light emitting device <NUM> comprises a controller <NUM> configured to control the tunable parameter or parameters of the light sources <NUM>, <NUM>, <NUM>, <NUM>, <NUM> and <NUM>. The controller <NUM> is thus in a signal transferring relationship with the respective light sources <NUM>, <NUM>, <NUM>, <NUM>, <NUM> and <NUM>, for instance by use of a wired or wireless connection.

It is also feasible to provide a light emitting device according to the invention with more than three clusters. It is also feasible to provide at least one cluster of a light emitting device according to the invention with more than pairs, such as four, five or six pairs, of light sources and lenses.

A light emitting device according to the invention may also comprise an array of clusters such as the clusters <NUM>, <NUM>, <NUM> shown in <FIG>. The light emitting device <NUM> thus comprises an array of 1x3 clusters. By way of example, a second row of three clusters similar to the clusters shown in <FIG> may be provided at another position in the Z-direction such as to provide an array of 2x3 clusters. In principle any suitable size of array is possible.

Turning now to <FIG>, a perspective view of the light emitting device <NUM> according to <FIG> and seen from another angle of view making all illuminated areas visible is shown. For the sake of simplicity, the lenses and light sources of each cluster are not shown explicitly on <FIG>. As may be seen, the first cluster <NUM> illuminates a first target area <NUM>, the second cluster <NUM> illuminates a second target area <NUM> and the third cluster <NUM> illuminates a third target area <NUM>. The first and second target areas <NUM> and <NUM> are arranged with an overlap, and the second and third target areas <NUM> and <NUM> are arranged with an overlap. Thereby a seamless transition between the target areas is obtained. To obtain this, the clusters <NUM>, <NUM>, <NUM> are arranged with a pitch p seen along the direction y, where the pitch p is smaller than the size of the illuminated areas <NUM>, <NUM>, <NUM> measured in the direction y.

In the following a number of examples of simulations performed on a light emitting device <NUM> according to the invention and as described above with reference to <FIG> will be described. The examples are described with reference to <FIG> and serve to illustrate the function of and effects obtained with a such light emitting device <NUM>.

<FIG> shows plots illustrating the irradiance created on a target surface <NUM> by using a light emitting device <NUM> according to <FIG>, where the optional third light source and lens are omitted, and where the first light source <NUM> and the second light source <NUM> are provided as point light sources. <FIG> shows plots similar to those of <FIG> and illustrating the irradiance created on a target surface <NUM> by using a light emitting device <NUM> according to <FIG>, where the first light source <NUM> and the second light source <NUM> are provided with a light emitting surface area of <NUM> × <NUM>. The first lens <NUM> and the second lens <NUM> used in these two examples were identical.

As may clearly be seen, for a given lens <NUM>, <NUM>, the use of light sources <NUM> and <NUM> with a light emitting surface area of <NUM> × <NUM> provides a more uniform image with a higher irradiance level as compared to the use of point light sources <NUM> and <NUM>. On the other hand, the use of point light sources <NUM> and <NUM> provides a considerably sharper image with a higher quality as compared to the use of light sources <NUM> and <NUM> with a light emitting surface area of <NUM> × <NUM>.

<FIG> shows a circular plot illustrating the direction of the irradiance created by using a light emitting device <NUM> according to <FIG>, where the optional third light source and lens are omitted, and where the first light source <NUM> and the second light source <NUM> are provided with a light emitting surface area of <NUM> × <NUM>. <FIG> shows a spherical plot illustrating the spatial direction of the irradiance created by using the same light emitting device as used to produce the result illustrated in <FIG>.

As may clearly be seen, for a given lens <NUM>, <NUM>, the use of light sources <NUM> and <NUM> with a light emitting surface area of <NUM> × <NUM> provides an output with a very well defined directionality, and thus provides for a particularly sharp pattern and thus resulting image on the target area <NUM>.

<FIG> shows a plot illustrating the irradiance created on a target surface <NUM> by using a light emitting device <NUM> according to <FIG>, where the optional third light source and lens are omitted, and where the first light source <NUM> and the second light source <NUM> are point light sources. <FIG> shows a plot similar to that of <FIG> and illustrating the irradiance created on a target surface <NUM> by using a light emitting device <NUM> according to <FIG>, where the optional third light source and lens are omitted, and where the first light source <NUM> and the second light source <NUM> have a light emitting surface area of <NUM> × <NUM>. Finally, <FIG> shows a plot illustrating the irradiance created on a target surface <NUM> by using a light emitting device <NUM> according to <FIG>, where the optional third light source and lens are omitted, and where the first light source <NUM> and the second light source <NUM> have a light emitting surface area of <NUM> x <NUM>. In all three cases identical lenses <NUM> and <NUM> were used. For all three plots (<FIG>) it applies that the lighter the gray tone on the plot, the higher the irradiance.

As may clearly be seen from <FIG>, for a given lens <NUM>, <NUM>, the use of light sources <NUM> and <NUM> with a light emitting surface area of <NUM> × <NUM> provides a more uniform image with a higher irradiance level as compared to the use of point light sources. On the other hand, the use of point light sources <NUM> and <NUM> provides a considerably sharper image with a higher quality as compared to the use of light sources <NUM> and <NUM> with a light emitting surface area of <NUM> × <NUM>. Likewise, the use of light sources <NUM> and <NUM> with a light emitting surface area of <NUM> × <NUM> provides a considerably sharper image with a higher quality as compared to the use of light sources <NUM> and <NUM> with a light emitting surface area of <NUM> x <NUM>. However, the use of light sources <NUM> and <NUM> with a light emitting surface area of <NUM> x <NUM> is seen to still yield a sharp image with a high quality.

Claim 1:
A light emitting device comprising at least one cluster (<NUM>) of light sources and lenses, the at least one cluster comprising:
at least a first light source (<NUM>) and a second light source (<NUM>), the first light source and the second light source being adapted for, in operation, emitting first respectively second light,
at least one first lens (<NUM>) associated with the first light source, and
at least one second lens (<NUM>) associated with the second light source, wherein
the first lens is configured to create a first illuminance pattern in a plane P and the second lens is configured to create a second illuminance pattern in the plane P, wherein
the first light source and the first lens and the second light source and the second lens, respectively, are arranged in a predefined distance D from the plane P, the predefined distance D being measured in a direction extending perpendicular to the plane P, wherein
the first light source and the first lens are arranged such that during operation an average emission direction of the first light is along a first axis (<NUM>), and the second light source and the second lens are arranged such that during operation an average emission direction of the second light is along a second axis (<NUM>), wherein
the first light source and the first lens and the second light source and the second lens, respectively, are oriented such that the first axis and the second axis extend at an angle φ with a plane H extending in parallel with and in the predefined distance D from the plane P and that the first axis and the second axis intersect at or in the plane P, wherein
the first light source and the first lens and the second light source and the second lens, respectively, are further arranged and on a straight line extending in parallel with the plane P and perpendicular to the direction in which the distance D is measured,
wherein the first lens and the second lens are freeform lenses, and
wherein the first illuminance pattern and the second illuminance pattern are mutually different illuminance patterns, each illuminance pattern comprising at least three first areas and at least three second areas, wherein the first areas have a first color and the second areas have a second color different from the first color and/or the first areas comprise a brightest area having a brightness Bb and the second areas are dark areas of a brightness Bd, and wherein Bd <= <NUM> * Bb, preferably Bd <= <NUM> * Bb, such as Bd <= <NUM> * Bb.