Abstract
The invention relates to a lighting system comprising 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 in between the first and second wall portion, wherein (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.
Claims
1. A lighting system comprising: a light area extending transverse to a main, axial direction, and a side wall extending downstream from the light area, defining a recess with a cross section, wherein 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, wherein the side wall comprises a first wall portion and a second wall portion located upstream of the first wall portion, and wherein a transparent pane is provided in between the first and second wall portion, and wherein essentially the whole second wall portion is screened by the first wall portion from all direct lines of view through the light exit window.
2. The lighting system according to claim 1, wherein the light area is formed by a LED panel having a diffuse surface.
3. The lighting system according to claim 1, wherein the transparent pane is specular Fresnel reflective.
4. The lighting system according to claim 1, wherein the first wall portion is capable of emitting light.
5. The lighting system according to claim 1, wherein the sidewall, the first and second wall portion thereof are circumferential around the recess and wherein the first wall portion is provided with a lighting arrangement for controlling at least one of color, intensity, contrast of the illumination, and shape from which light is provided by the first wall portion.
6. The lighting system according to claim 1, wherein the first wall portion having a height H1 comprises a transverse wall portion extending at the transparent pane in a radial direction over a width Wt into the recess having a width Wr for screening the second wall portion having a height H2 from said direct line of view, wherein
H2<=H1*Wt/(Wr−Wt).
7. The lighting system according to claim 1, wherein the first wall portion having a height H1 is offset from the second wall portion by a distance D in a radial direction into the recess having a width Wr for screening the second wall portion with a height H2 from said direct line of view, wherein
H2<=H1*D/(Wr−2*D).
8. The lighting system according to claim 1, wherein the light area and the transparent pane are spaced apart by a distance in the range of 0.1-7.5 cm, preferably 0.5-5 cm, most preferably 0.5-1.5 cm.
9. The lighting system according to claim 1, wherein the transparent pane extends over the full cross sectional area Ra of the recess at the first wall portion.
10. The lighting system according to claim 1, wherein the transparent pane is made of clear, colorless glass, PMMA or PC.
11. The lighting system according to claim 1, wherein the second wall portion has a white colored, diffuse reflective surface facing the recess.
12. The lighting system according to claim 1, wherein the first wall portion has a white colored, diffuse reflective surface facing the recess.
13. The lighting system according to claim 1, wherein the light area emits light with a color temperature or color correlated color temperature in the range of 6500-20000K, preferably in the range of 9000-15000K.
14. The lighting system according to claim 1, wherein the first wall portion emits light with a color temperature or 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, wherein the artificial window or the recessed wall arrangement comprises the lighting system according to claim 1.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0033] The invention will now be further explained by means of the schematic drawings which are intended to elucidate the invention rather than to limit the scope of the invention, thereto some dimensions may not be up to scale but may be exaggerated for explanation purposes. In the drawings:
[0034] FIG. 1 shows a first embodiment of a lighting system according to the invention;
[0035] FIG. 2 shows a second embodiment of a lighting system according to the invention;
[0036] FIG. 3A-B shows the conditions for screening of the second wall portion for the first and second embodiment;
[0037] FIG. 4 shows a third embodiment of a lighting system according to the invention;
[0038] FIG. 5 shows a part of a detailed cross section of an embodiment of light area; and
[0039] FIG. 6 shows a lighting system built into a false ceiling.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0040] FIG. 1 shows a first embodiment of an artificial window, for example an artificial skylight, of a lighting system 1 according to the invention. The lighting system comprises a light area 3 (also referred to as light generating area or light transmitting area) extending transverse to a main, axial 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 a base 11 of the recess and a light exit window 13 is located downstream at a top 15 of the recess opposite the light area. The side wall comprises a first wall portion 17 and a second wall portion 19 located upstream of the first wall portion, and a transparent pane 21 is provided in between the first and second wall portion. The second wall portion is screened by the first wall portion from a direct line of view through the light exit window, in that the first wall portion is offset from the second wall portion in a radial direction into the recess. This is further explained in FIG. 3A. The transparent pane, the light area and the second wall portion define a space 25 which can house an object. The transparent pane is clear and colorless, is made from PMMA and exhibits a specular Fresnel reflection. The first wall portion is coated with a white, diffuse reflective coating 27 of white paint. The light generating area comprises a side-lit light guide 33 provided with an outcoupling structure 45 and with LEDs as a light source 35.
[0041] FIG. 2 shows a second embodiment of an artificial window of a lighting system 1 according to the invention. The second embodiment of the lighting system is similar to the first embodiment, but yet differs in that the first wall portion 17 comprises a transverse wall portion 29 extending at the transparent pane 21 in a radial direction with respect to main axis 5 into the recess 9 for screening the second wall portion 19 from said direct line of view. This is further explained at the hand of FIG. 3B. Furthermore, said second embodiment comprises a relatively large space 25, formed by the light area 3, the transparent pane and the second wall portion to house an object 31, in the figure a tree leaf. Due to relatively large height H2 of the second wall portion, it unintentionally could be visible through the light exit window 13, and thereto the second wall portion is provided with a white diffuse reflective coating 27 of aluminum oxide.
[0042] FIG. 3A-B shows the conditions for screening of the second wall portion for the first and second embodiment. FIG. 3A shows the lighting system 1 according to the first embodiment shown in FIG. 1. In this first embodiment the first wall portion 17 has a height H1 which is offset from the second wall portion 19 by a distance D in a radial direction with respect to main axis 5 into the recess 9 having a width Wr, here being the width of the light exit window 13, for screening the second wall portion with a height H2 from a direct line of view 23, wherein
H2<=H1*D/(Wr−2*D).
[0043] FIG. 3B shows the lighting system 1 similar to the second embodiment shown in FIG. 2. In this second embodiment the first wall portion 17 has a height H1 which comprises a transverse wall portion 29 extending at the transparent pane 21 in a radial direction with respect to main axis 5 over a width Wt into the recess 9 having a width Wr, here being the width of light generating area 3, for screening the second wall portion 19 having a height H2 from said direct line of view 23 through the light exit window 13, wherein
H2<=H1*Wt/(Wr−Wt).
[0044] FIG. 4 shows a third embodiment of an artificial window, for example a recessed wall portion, of a lighting system 1 according to the invention. The lighting system comprises a light area 3 extending transverse to a main, axial 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 a base 11 of the recess and a light exit window 13 is located downstream at a top 15 of the recess opposite the light area. The side wall comprises a first wall portion 17 and a second wall portion 19 located upstream of the first wall portion, and a transparent pane 21 is provided in between the first and second wall portion. The second wall portion is screened by the first wall portion from a direct line of view through the light exit window, in that the first wall portion is offset from the second wall portion in a radial direction into the recess. The transparent pane, the light area and the second wall portion define a space 25 which can house an object. A part 37 of the first wall portion 17 is translucent and made light emitting. Thereto the first wall portion is backlit by an array of LEDs 39 and provided with a diffuser 41. In operation said part of the first wall portion is illuminated and a reflection of said part is visible as a virtual image 43 in the clear transparent pane, thus enhancing the desired realism of the artificial window.
[0045] FIG. 5 shows a part of a detailed cross section of an embodiment of light area 3 as shown in FIG. 4. The light generating area comprises a clear, light transmissive light guide 33 side-lit by LEDs 35 and provided with a light out-coupling structure 45 on a first side, first main surface 47, facing a reflector 49. In front of a second side, main surface 51, of the light guide a diffuser 53 is provided. A clamp or housing wall 55 with cover 57 is provided to shield the LEDs from direct view, to maintain the various parts of the light generating area mutually positioned and to attach the light generating area to the second wall portion 19 (partially shown). In other embodiments the light guide plate can be back-lit instead of side lit, and at least one of the cover, the reflector and the outcoupling structure can be omitted. The diffuser can be scattering or homogenize light by beam widening via refraction or TIR (total internal reflection).
[0046] FIG. 6 shows a lighting system 1 built into a false ceiling 59. The first 17 and second wall portion (not visible) thereof are circumferential around the recess 9. The first wall portion is provided with a lighting arrangement (not shown, but see FIG. 4) for controlling at least one of color, intensity, contrast of the illumination, and shape from which light is provided by at least a part 61 of one sub-wall 65 of the first wall portion. Thus, the first side wall comprises light emitting parts 61 and triangular non-light emitting parts 63. Thus an effect of a sharp boundary 67 is created, which replicates the sharp lines created by a distant point light source such as the sun. In this way, the illumination shape appears to have been created by a sunlit light transmitting or generating area. The bright light emitting parts are reflected and clearly visible as virtual images 43 in the transparent pane 21.
[0047] Finally, the following is noted: [0048] the direct light path (hence without being reflected at for example first wall portions 17, see FIG. 4)) from main surface 51 (see FIG. 5) of the light guide up to and including the light exit window is essentially free from a diffuser (the reflection of the first wall portions 17 in the main surface 51 of the light guide is visible from outside downstream the lighting system in an unblurred/specular/non-scattered manner). The approach of the current invention disclosure is to prevent that the reflections of the sidewalls become blurred. [0049] light area (3) is formed by a light guide which is (back-lit but preferably side-)lit by LEDs, see e.g. description FIG. 5 [0050] enhancing the illusion of being able to “view around the corner” of the clear material pane, into the artificial sky. It is achieved by i) limiting the view at the clear pane in reducing its surface area with respect to the surface area of the recessed sky panel that is arranged to be slightly spaced apart from the clear pane and ii) in providing inner sidewalls of sufficient height in relation to the height of the spacer. Thus, the artificial sky is suggested to “float” above the clear pane without providing any witness to the spacer and the finite size of a recessed panel.
