Lighting system and artificial window

Abstract

To counteract a disadvantage of a known artificial skylight device.SOLUTION: The invention relates to a lighting system, which comprises a light area and a side wall around the light area defining a recess. The light area is located at a base of the recess, and a light exit window is located downstream at a top of the recess opposite the light area. The side wall comprises a first wall portion, and a second wall portion located upstream of the first wall portion. A clear transparent pane is provided between the first and second wall portions, where (essentially the whole of) the second wall portion is screened by the first wall portion from a direct line of view through the light exit window.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a lighting system and an artificial window. [Background technology]

[0002] Artificial skylight devices are a relatively new class of devices that have recently attracted a lot of attention. Their purpose is to provide humans with a feeling of connection with nature while being indoors where access to natural light may be completely or partially denied. Examples of such indoor spaces are offices, corridors, subways, underground malls, stations, tunnels, hospitality areas, hospitals, airplanes, submarines, etc. Currently, there are many different artificial skylights, ranging from (very) low-end, low-cost, static (backlit) posters to (mostly) impractical, unaffordable, huge size and weight, high volume, high-tech devices, more expensive, high-resolution dynamic TV and / or projector-based devices deploying wavelength-dependent nanoparticle scattering, known as Rayleigh scattering (the reason the sky is blue). A relatively simple and low-cost artificial skylight device is known from US 9,488,327 B2. The device consists of a set of one or more side walls with a recessed panel that acts as a diffuse light source representing blue sky, and a triangular shaped portion that can be back-lit, thus simulating a sunlit area while providing a visual cue toward the distant position of the sun in the sky. However, this known artificial skylight device has the disadvantage that it only provides a moderately realistic sensation of an actual window or skylight. Summary of the Invention [Problem to be solved by the invention]

[0003] It is an object of the present invention to address the disadvantages of known artificial skylight devices. [Means for solving the problem]

[0004] For this purpose, the present invention provides a light area extending transversely to the main axis direction, a sidewall extending downstream from the light region defining a recess having a cross section; 1. A lighting system comprising: the light region is located at the bottom of the recess and the light exit window is located downstream at the top of the recess facing the light region; The side wall includes a first wall portion and a second wall portion located upstream of the first wall portion, a transparent pane is disposed between the first wall and the second wall; It proposes an illumination system in which essentially the entire second wall is screened from a direct line of view through the light exit window by the first wall.

[0005] In the context of the present invention, the expression "essentially" is to be understood as almost completely or completely, and it should be taken into account that the inner surface of the second wall of the side wall, which is already hidden from said direct line of sight, for example by the part where the second wall of the side wall is attached to another part, is not necessarily hidden by the first wall. Moreover, it is clear that the screening of the second wall relates to the inner surface of the second wall, i.e. the side of the second wall facing the transparent pane.

[0006] The lack of immersive / realistic effect was found to be due to reflections of the backlit side walls, which appear as blurred and smeared-out areas on the diffuse surface of the recessed panel. The problem with these blurred and smeared reflections is that the sky appears as a surface with different colored areas visible along two or more sides of the recessed panel. As a result, the human eye may focus on the surface of origin of the color difference, which is the surface / light area of ​​the panel, and this significantly reduces the sense of depth. Furthermore, the adverse effect of reflections may be so strong that, for example, when the entire circumference of the first wall is lit / backlit, a clearly visible circle of different color appears in the center of the light area ("sky"), which further reduces the sense of depth. Also, the overall illusion of the artificial skylight is compromised, while the reference to the position of the sun in the sky disappears, since there are no clear shadows. Various options are envisaged to solve these problems, but most of the options have certain other disadvantages. For example, one option to reduce the negative effect of the backlit sidewall is to reduce the visibility by decreasing the light intensity of the backlit part. However, at that point, the artificial "sun" becomes less intense and the realistic illusion is broken. Another option is to increase the vertical distance between the first wall and the recessed light area by deploying a more forgiving sky configuration, for example an indirectly lit (half) dome, an ellipsoid, a sphere, a tubular cavity of any other integrating body (acting as a sky). Moreover, this comes at the expense of a significant increase in the total built-in depth of the device, especially for devices with large sky areas.Yet another option, as implemented by Mitsubishi Electric and COELUX with slanted sidewalls, is to tilt the sidewalls outwards so that little to no light is directed towards the light area (sky).

[0007] The lighting system may be characterized in that the light area is formed by an LED panel with a diffusing surface, thus enhancing the effect of infinity. Such an LED panel may be LEDs mounted on a carrier combined with a separate diffuser or an integrated diffuser. The diffuser has the diffusing surface and is arranged between the carrier and a transparent pane. The separate diffuser may be spaced apart from the carrier, but alternatively may be arranged on the surface of the carrier. Furthermore, a diffuser is arranged between the array of LEDs and the transparent pane to diffuse the light emitted by the LEDs during operation.

[0008] The approach of the present disclosure is to prevent the sidewall reflection from being blurred. This is achieved by providing a clear transparent window between the recessed panel and one or more (back-lit) sidewalls. Furthermore, a second wall and a homogenous diffuse lit surface, such as a very diffuse and homogenous lit sky-blue recessed LED panel, are provided upstream of the pane, and the viewing angle limiting frame height of the first wall is large enough to limit the direct line of sight through the light exit window in the frame of the second wall and sky-panel, to ensure that there are no witnesses to the origin of the sky, while at the same time providing a feeling of sufficient structural integrity of the (suspended) ceiling. It has been found that the second wall part should not be visible through the transparent pane, as this would reduce the realistic effect of the artificial window.

[0009] The advantages of such clear panes or sheet materials, e.g. made of PC, PMMA or (window) glass, are: - the sheet or pane acts as a semi-mirror; and - grazing angle light rays are redirected towards the opposing sidewall, thereby reducing the amount of sidewall light that could have reached the diffusing surface of the recessed panel in the first place; That is the thing.

[0010] The positive effect of having an intermediate pane of clear material between the light area and the first wall is that, as a first visual cue, a clear and sharp reflection of the "sunlit" inner first wall is clearly visible in contrasting proportions on both sides of the clear glass pane. Furthermore, as a second visual cue, both the real and reflected images of the shadowed areas give clear guidance toward the virtual sun's position in the air without the need to look at the sun. Furthermore, as a third visual cue, the glass pane also shows the reflection (virtual image) of other objects in the space below the canopy, appearing as an augmented image in the air at a focal plane beyond the surface of the glass pane. The fact that the second wall is hidden from the direct line of sight through the light exit window by the first wall prevents a potential, unrealistic disturbance of the reflection (virtual image) due to the visibility of the second wall. Thus, combined with the uniform appearance of the blue sky, the depth of the blue sky light area appears infinite as there is no indicator to give a measure of "distance" towards the sky.

[0011] Typically, the sidewall has dimensions such that it can be considered as an axial extension of the periphery of the light area, in other words, the sidewall has dimensions such that it can be considered as a downstream, axially extending wall around the light area. Typically, the transparent pane is essentially non-diffusing and non-scattering and is positioned directly opposite the light area, i.e., there is no separate pane, sheet or plate between the light area and the transparent pane, and substantially all light from the light area is directly incident on the transparent pane.

[0012] The lighting system may be characterized in that the transparent pane is specular Fresnel reflective. The Fresnel reflection of the specular, clear, transparent pane further enhances the sense of depth as the reflected image is sharpened, improving the suggestion of a real window. Typically, the lighting system may be characterized in that the transparent pane extends over the full cross sectional area Ra of the recess in the first wall, to further enhance the desired realism of the artificial skylight solution.

[0013] The lighting system may have the feature that the first wall can emit light. In addition to the light area, the first wall may be a light transmitting area, such as a side-lit light guide, or a light generating area (and may be referred to herein as a light generating area), such as a back-lit area or an OLED, and may be equipped with a light source. The use of lighting in the sidewall helps to enhance the realism of the lighting system. In this case, the light source is intended to reproduce natural sunlight, or even lighting from the moon or stars. If the light area and the first wall are lit in the right proportions / ratios, the artificial sky will have an even improved and strong sense of depth, with a clear depth that extends far beyond the surface of the transparent pane. Furthermore, some of the light originating from the back-lit sidewall preferably reaches the opposing non-illuminated sidewall surface to "neutralize" the bluish appearance of that sidewall as a result of the blue sky engine. In this way, the illuminated side wall(s) compensate for the blue light coming from the artificial skylight and therefore the recessed walls appear white (or any other color / color temperature of sunlight desired) to the observer. Apart from color issues, bright recessed walls enhance the realism of the sunlight effect. The lighting system can be used or included as an artificial window in the ceiling, but also as an artificial vertical window in the wall.

[0014] The lighting system may be characterized in that the sidewall, the first wall portion of the sidewall and the second wall portion of the sidewall are circumferentially around the recess, the first wall portion comprising a shape in which light is provided by (a part of) at least one sub-wall of the first wall portion and a lighting arrangement for controlling at least one of the following: color, intensity, contrast of the lighting. In this case, the lighting system has a circumferential sidewall in which the first wall portion comprises a set of sub-sidewalls, each sub-sidewall comprising a rectangular light-emitting area. This defines a basic recess for the polygonal panel.

[0015] In a first example with a set of side walls, each side wall may include a rectangular light-emitting area formed from two independently controllable triangular light-emitting areas. With one triangle illuminated, a sharp boundary effect may be created, which may reproduce the sharp line created by a distant point light source such as the sun. In this way, the triangular illumination shape may appear to be created by a sunlit light-transmitting or -producing area. If both triangles are illuminated, the side wall may appear to face the sun, whereas if one triangle is illuminated, the side wall may appear to be disposed laterally to the sun. If neither triangle is illuminated, the side wall may appear to be in shadow.

[0016] In another example with a set of side walls, each side wall contains a rectangular light emitting area formed from four independently controllable triangular light emitting areas, each of which can have an apex in the center of the rectangular light emitting area. This means that the triangles can be defined with an inverse slope. This means that the lighting system does not have to be oriented in any special way to reproduce the shadows caused by the sun.

[0017] In another example with a set of side walls, two side walls each include a rectangular light-emitting area formed from a number of independently controllable triangular light-emitting areas, each of which can have an apex at one corner of the rectangular light-emitting area. This means that the triangles can be defined with various inclinations. This means that the lighting system can reproduce the lines cast by the sun at different heights in the sky, representing different times of day. There can be four side walls, two of which (with a number of triangles) face each other and the other two side walls with a number of rectangular light-emitting areas. The side walls that are arranged laterally (with respect to the direction of the incoming light from the sun) have triangles, whereas the front and back walls have rectangles. This means that all four side walls can be controlled to give an overall impression corresponding to daylight illumination from a specific sun position. The light-transmitting or light-generating areas typically have a rectangular or square shape, but other shapes are also possible.

[0018] The light source can provide a first color for light emitted in a normal direction to the light-generating area and a second, different color for light emitted in a direction oblique to the normal direction. For example, the second color can have a stronger blue component than the first color. This arrangement functions as an artificial skylight, i.e., a system that provides an appearance that attempts to reproduce the appearance of a ceiling window when lit by daylight (direct sunlight or full light such as might be seen on an overcast day). This arrangement provides a whiter downward task light that represents the sun and a bluer light in the other direction that represents the daytime sky. Sidewall lighting can prevent the sidewall from appearing blue, which does not match the effect observed through a real window.

[0019] Even greater realism can be achieved by creating clearly defined light / dark boundaries as explained above. These measures can be used to greatly enhance the realism of artificial skylight solutions.

[0020] In a first configuration, the illumination system includes a first wall portion having a height H1 and a transverse wall portion extending radially in the transparent pane across a width Wt within a recess having a width Wr to hide a second wall portion having a height H2 from said direct line of sight; H2<=H1*Wt / (Wr-Wt) The present invention can be characterized in that:

[0021] Alternatively, in a second configuration, the illumination system comprises a first wall having a height H1 and offset radially from the second wall by a distance D into a recess having a width Wr to hide a second wall having a height H2 from said direct line of sight; H2<=H1*D / (Wr-2*D) The present invention can be characterized in that:

[0022] Thus, in both the first and second configurations, it is ensured that the second wall is not visible through the light-exit window and therefore that the desired realism of the artificial skylight is not adversely affected. In practice, the height H2 of the second wall can be practically zero, but is typically greater than zero. The second wall is that part of the side wall that is between the light area and the transparent pane and that forms a very small space between the light area and the transparent pane. Moreover, preferably, the second wall has a small height H2 and the light area and the transparent pane are spaced apart by a distance H2 that is in the range of 0.1-7.5 cm, preferably 0.5-5 cm, most preferably 0.5-1.5 cm. In practice, it has been found that an upper limit for the height H2 is 7.5 cm, since otherwise the size of the cross-sectional area Ra of the recess in the first wall would be too small and / or the height H1 of the first wall would be too large, resulting in too high a built-in depth of the lighting system. Therefore, from this point of view, the height H2 should be as small as possible, and a preferred upper limit for H2 is 5 cm. On the other hand, the height H2 should be large enough to avoid optical contact between the light area and the transparent pane, and therefore should be at least 0.1 cm, but preferably large enough to accommodate objects for further enhancement of the realism of the artificial skylight solution. Therefore, H2 is preferably in the range of 0.5 cm to 1.5 cm. In order to accommodate objects for further enhancement of the realism, the lighting system can have the feature that at least one object selected from handlebars, dirt, and artificial drops of birds-po, leaves, raindrops, and / or grains of sand are placed on the clear pane or placed in the space between the light area and the clear transparent pane.

[0023] The lighting system may have the feature that the transparent pane is made of clear, colorless glass, PMMA or PC, as these materials are typically used and are convenient to use as window panes, and resemble as closely as possible real window glass panes, thus enhancing the desired realism of the artificial skylight solution.

[0024] The lighting system may be characterized in that the second wall has a white diffusely reflective surface facing the recess. Such a configuration of the second wall has been found to improve the effect of the second wall on the desired realism of the artificial skylight solution compared to other configurations of the second side wall. Also, the desired realism of the artificial skylight solution is satisfactorily maintained even when the second wall is unintentionally not completely hidden from a direct line of sight through the light-exit window.

[0025] The lighting system may be characterized in that the first wall has a white diffuse reflective surface facing the recess, thus enhancing the visibility of the (virtual) reflection of the first wall in the clear transparent pane that appears as an aerial augmented image, thus enhancing the desired realism of the artificial skylight solution.

[0026] The first wall can emit white light and / or colored light, for example with a Lambertian intensity distribution. Furthermore, the lighting system can be characterized in that the light area emits light with a color temperature or color-correlated color temperature in the range of 6500-20000K, including the color temperatures of both overcast and clear blue sky, preferably in the range of 9000-15000K for the color temperature of clear blue sky. Additionally or alternatively, the lighting system can be characterized in that the first wall emits light with a color temperature or color-correlated color temperature in the range of 3500-6000K, preferably in the range of 4000-5500K. In any of these solutions, the appearance of the side wall can be matched to the lighting effect desired from the light area.

[0027] The lighting system according to the invention may be used as an artificial window or as a recessed wall arrangement. Indoor spaces, such as offices, corridors, subways, underground malls, stations, tunnels, hospitality areas, hospitals, airplanes, submarines, etc., where natural light is completely or partially absent, are among the suitable application areas for the lighting system according to the invention. [Brief description of the drawings]

[0028] The present invention will now be further described by means of schematic drawings, which are intended to clarify the invention rather than to limit its scope, and for which some dimensions are not to scale and may be exaggerated for illustrative purposes. [Figure 1] FIG. 1 shows a first embodiment of a lighting system according to the invention. [Diagram 2] FIG. 2 shows a second embodiment of a lighting system according to the invention. [Diagram 3] 3A to 3B show conditions for hiding the second wall portion in the first and second embodiments. [Figure 4] FIG. 4 shows a third embodiment of a lighting system according to the invention. [Diagram 5] FIG. 5 shows a detailed cross-sectional portion of one embodiment of a light region. [Figure 6] FIG. 6 shows a lighting system integrated into a false ceiling. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0029] FIG. 1 shows a first embodiment of an artificial window, for example an artificial skylight, of an illumination system 1 according to the invention. The illumination system comprises a light area 3 (also called light-generating or light-transmitting area) extending transversely to a main axis direction 5, and a side wall 7 extending downstream from the light area, defining a recess 9 with a cross section Ra. The light area is located at the bottom 15 of the recess, and a light-exit window 13 is located downstream at the top 11 of the recess opposite the light area. The side wall comprises a first wall 17 and a second wall 19 located upstream from the first wall, and a transparent pane 21 is provided between the first and second walls. The second wall is hidden by the first wall from a direct line of sight through the light-exit window, the first wall being offset from the second wall radially into the recess. This is further explained in FIG. 3A. The transparent pane, the light area and the second wall define a space 25 in which an object can be accommodated. The transparent pane is colorless and transparent, made from PMMA, and exhibits specular Fresnel reflection. The first wall is coated with a white diffuse reflective coating 27 of white paint. The light-generating region includes a side-illuminating light guide 33 with an outcoupling structure 45 and with LEDs as light sources 35.

[0030] Figure 2 shows a second embodiment of the artificial window of the lighting system 1 according to the invention. The second embodiment of the lighting system is similar to the first embodiment, except that the first wall 17 includes a lateral wall 29 extending radially to the main axis 5 at the transparent pane 21 in the recess 9 to hide the second wall 19 from said direct line of sight. This is further explained in figure 3B. Furthermore, the second embodiment includes a relatively large space 25 formed by the light area 3, the transparent pane and the second wall to accommodate an object 31, in the figure a tree leaf. Due to the relatively large height H2 of the second wall, the second wall can be unintentionally seen through the light exit window 13, for which reason the second wall is provided with a white diffuse reflection coating 27 of aluminium oxide.

[0031] Figures 3A-3B show the conditions for hiding the second wall for the first and second embodiments. Figure 3A shows the lighting system 1 according to the first embodiment shown in Figure 1. In this first embodiment, the first wall 17 has a height H1 and is offset from the second wall 19 by a distance D radially with respect to the main axis 5 in a recess 9 having a width Wr, here the width of the light-exit window 13, in order to hide the second wall having a height H2 from the direct line of sight 23; H2<=H1*D / (Wr-2*D) It is.

[0032] Fig. 3B shows the lighting system 1 according to the second embodiment shown in Fig. 2. In this second embodiment, the first wall 17 has a height H1 and includes a lateral wall 29 extending radially in the transparent pane 21 relative to the main axis 5 over a width Wt in a recess 9 having a width Wr, here the width of the light-generating area 3, in order to hide a second wall 19 having a height H2 from a direct line of sight 23 through the light-exit window 13; H2<=H1*Wt / (Wr-Wt) It is.

[0033] FIG. 4 shows a third embodiment of an artificial window, for example a recessed wall portion, of an illumination system 1 according to the invention. The illumination system comprises a light area 3 extending transversely to the main axis direction 5 and a side wall 7 extending downstream from the light area, defining a recess 9 with a cross section Ra. The light area is located at the bottom 15 of the recess and a light exit window 13 is located downstream at the top 11 of the recess opposite the light area. The side wall comprises a first wall 17 and a second wall 19 located upstream from the first wall, and a transparent pane 21 is provided between the first and second walls. The second wall is hidden by the first wall from a direct line of sight through the light exit window, and the first wall is offset from the second wall radially into the recess. The transparent pane, the light area and the second wall define a space 25 in which an object can be accommodated. A portion 37 of the first wall 17 is translucent and adapted to emit light. To that end, the first wall is back-illuminated by an array of LEDs 39 and is provided with a diffuser 41. In operation, said portion of the first wall is illuminated and a reflection of said portion is visible in the clear transparent pane as a virtual image 43, thus enhancing the desired realism of the artificial window.

[0034] FIG. 5 shows a detailed cross-section of one embodiment of the light region 3 as shown in FIG. 4. The light-generating region includes a clear, light-transmissive light guide 33 that is side-illuminated by LEDs 35 and is provided with a light out-coupling structure 45 on a first side, first major surface 47 facing the reflector 49. A diffuser 53 is provided in front of a second side, major surface 51 of the light guide. A clamp or housing wall 55 with a cover 57 is provided to shield the LEDs from direct view, to keep the various parts of the light-generating region positioned relative to one another, and to attach the light-generating region to a second wall 19 (partially shown). In other embodiments, the light guide plate can be back-illuminated instead of side-illuminated, and at least one of the cover, reflector and out-coupling structure can be omitted. The diffuser can scatter or homogenize the light by beam widening via refraction or TIR (total internal reflection).

[0035] FIG. 6 shows a lighting system 1 integrated in a false ceiling 59, whose first wall 17 and second wall (not visible) are circumferential around the recess 9. The first wall is provided with a shape in which light is provided by a part 61 of at least one sub-wall 65 of the first wall, and with a lighting arrangement (not shown, but visible in FIG. 4) for controlling at least one of the color, intensity and contrast of the lighting. Thus, the first side wall includes a light-emitting part 61 and a triangular non-light-emitting part 63. Thus, an effect of a sharp boundary 67 is created, which reproduces the sharp line created by a distant point source such as the sun. In this way, the lighting shape appears to be created by a sunlit light-transmitting or -producing area. The bright light-emitting part is reflected as a virtual image 43 in the transparent pane 21 and is clearly visible.

[0036] Finally, the following is noted: - The direct light path (and thus the light path that is not reflected e.g. at the first wall 17, see FIG. 4) from the main surface 51 of the light guide (see FIG. 5) to the light exit window and including the light exit is essentially diffuser free (the reflection of the first wall 17 at the main surface 51 of the light guide appears unblurred / specular / free of scattering from the outside downstream of the illumination system). The approach of the present disclosure is to prevent the side wall reflections from becoming blurred. The light area (3) is formed by a light guide which is illuminated (back-illuminated, but preferably laterally) by LEDs (see for example the description of FIG. 5). - The artificial sky enhances the illusion of being able to "see around the corners" of the clear material pane. This is achieved by i) limiting the visibility at the clear pane by making the surface area of ​​the clear pane small relative to the surface area of ​​the recessed sky panel that is placed slightly away from the clear pane, and ii) providing an inner sidewall of sufficient height relative to the height of the spacer. Thus, the artificial sky is imagined to "float" above the clear pane without providing a witness of the finite size of the spacer and the recessed panel.

Claims

1. a light region extending transversely to the main axis direction; a sidewall extending downstream from the light region defining a recess having a cross section; 1. A lighting system comprising: the light area is located at the bottom of the recess and a light exit window is located downstream at the top of the recess facing the light area; The side wall includes a first wall portion and a second wall portion located upstream of the first wall portion, a transparent pane is disposed between the first wall and the second wall; 13. An illumination system, wherein essentially the entire second wall is hidden from a direct line of sight through the light exit window by the first wall.

2. 10. The lighting system of claim 1, wherein the light area is formed by an LED panel having a diffusive surface.

3. 3. The lighting system according to claim 1 or 2, wherein the transparent pane is specular Fresnel reflective.

4. 4. The lighting system according to claim 1, wherein the first wall (12) is capable of emitting light.

5. 5. The lighting system of claim 1 , wherein the sidewall, the first wall portion of the sidewall and the second wall portion of the sidewall are circumferentially around the recess, and the first wall portion comprises a lighting arrangement for controlling a shape in which light is provided by the first wall portion and at least one of a color, intensity, contrast of the lighting.

6. the first wall portion having a height H1 includes a lateral wall portion extending radially in the transparent pane over a width Wt within the recess having a width Wr to conceal the second wall portion having a height H2 from the direct line of sight; H2<=H1*Wt / (Wr-Wt) 6. The lighting system according to claim 1 , wherein:

7. the first wall portion having a height H1 is radially offset from the second wall portion having a height H2 by a distance D within the recess having a width Wr to hide the second wall portion from the direct line of sight; H2<=H1*D / (Wr-2*D) 6. The lighting system according to claim 1 , wherein:

8. 8. The lighting system according to any one of the preceding claims, wherein the light area and the transparent pane are spaced apart by a distance in the range of 0.1 to 7.5 cm, preferably 0.5 to 5 cm, most preferably 0.5 to 1.5 cm.

9. 9. The lighting system according to claim 1, wherein the transparent pane (12) extends over the entire cross-sectional area of ​​the recess (12) in the first wall (10).

10. 10. The lighting system according to claim 1, wherein the transparent pane is made of clear and colorless glass, PMMA or PC.

11. 11. The illumination system according to claim 1, wherein the second wall (12) has a white diffusely reflective surface (14) facing the recess (12).

12. 12. The illumination system according to claim 1, wherein the first wall (12) has a white diffusely reflective surface (14) facing the recess (12).

13. 13. The lighting system according to any one of the preceding claims, wherein the light area emits light having a color temperature or a color-correlated color temperature in the range of 6500-20000K, preferably in the range of 9000-15000K.

14. 14. The lighting system according to any one of the preceding claims, wherein the first wall (10) emits light having a color temperature or a color-correlated color temperature in the range of 3500-6000K, preferably in the range of 4000-5500K.

15. An artificial window or a recessed wall arrangement, said artificial window or said recessed wall arrangement comprising an illumination system according to any one of claims 1 to 14.

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