A LIGHTING SYSTEM AND A METHOD FOR IMPROVING GROWTH CONDITIONS FOR PLANTS

Abstract

A lighting system is for providing photosynthetically stimulating artificial light to a specified target area where such artificial light is needed. The lighting system has at least one luminaire with a light source. The luminaire emits photosynthetically stimulating light at a narrow beam angle of less than and including 20° (FWHM). The lighting system has means for positioning the at least one luminaire at a distance of minimum 20 m from the specified target area measured in a light beam direction, and the luminaire is adapted to illuminate the specified target area with a minimum photosynthetic photon flux density of 140 μmol/s/m.sup.2. A method is for improving the growth conditions for plants in need of light at a specified target area by exposing the plants to a photosynthetically artificial light from a light source.

Claims

1. A lighting system for providing photosynthetically stimulating artificial light to a specified target area where such artificial light is needed, said lighting system comprising at least one luminaire with a light source, wherein the luminaire emits photosynthetically stimulating light at a narrow beam angle of less than and including 20° (FWHM), the lighting system further comprising means for positioning the at least one luminaire at a distance of minimum 20 m from the specified target area measured in a light beam direction, and wherein the luminaire is adapted to illuminate the specified target area with a minimum photosynthetic photon flux density of 140 μmol/s/m.sup.2.

2. The lighting system according to claim 1, wherein the luminaire emits photosynthetically stimulating light at a narrow beam angle of more than and including 3° (FWHM).

3. The lighting system according to claim 1, wherein the luminaire illuminates the specified target area with a minimum of 210 μmol/s/m.sup.2.

4. The lighting system according to claim 1, wherein the target area is illuminated with a lighting uniformity of at least 0.6.

5. The lighting system according to claim 1, wherein the light source comprises LED lamps.

6. The lighting system according to claim 1 4, wherein the light source comprises laser diodes.

7. The lighting system according to claim 1, wherein the luminaire is mounted tiltable.

8. The lighting system according to claim 1, wherein the light source is tiltable relative to the luminaire.

9. The lighting system according to claim 1, wherein the means for positioning the at least one luminaire comprises a rim portion of a roof of a sports stadium.

10. The lighting system according to claim 1, wherein the means for positioning the at least one luminaire comprises alight mast.

11. The lighting system according to claim 1, wherein the lighting system comprises a monitoring system for monitoring and estimation of the needs for artificial lighting on all parts of the target area in order to obtain acceptable growth conditions for the grass.

12. The lighting system according to claim 11, wherein the monitoring system comprises at least one camera.

13. The lighting system according to claim 1, wherein the lighting system comprises a floodlighting system.

14. A floodlighting system for illuminating a grass field of a stadium, wherein the floodlighting system comprises a lighting system for providing photosynthetically stimulating artificial light to a specified target area where such artificial light is needed, said lighting system comprising at least one luminaire with a light source, wherein the luminaire emits photosynthetically stimulating light at a narrow beam angle of less than and including 20° (FWHM), the lighting system further comprising means for positioning the at least one luminaire at a distance of minimum 20 m from the specified target area measured in a light beam direction, and wherein the luminaire is adapted to illuminate the specified target area with a minimum photosynthetic photon flux density of 140 μmol/s/m.sup.2.

15. A method for improving growth conditions for plants in need of light at a specified target area by exposing the plants to a photosynthetically artificial light from a light source, wherein the method comprises to provide a luminaire comprising the light source, said luminaire is adapted to emit the photosynthetically artificial light at a narrow beam angle of less than and including 20° (FWHM), the light source is positioned at a distance of minimum 20 m from the specified target area, and the plants in the specified target area are illuminated with a minimum photosynthetic photon flux density of 140 μmol/s/m.sup.2.

16. The method according to claim 15, wherein the specified target area is illuminated with a minimum of 210 μmol/s/m.sup.2.

17. The method according to claim 15, wherein the target area comprises grass in a stadium.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0058] In the following is described examples of preferred embodiments illustrated in the accompanying drawings, wherein:

[0059] FIG. 1 shows a schematic drawing of a luminaire of the lighting system for stimulating growth of plants;

[0060] FIG. 2 shows a simulated contour plot of light intensity isolines using 506 luminaires shown in FIG. 1 to illuminate a target area that is 100 meters long and 64 meters wide;

[0061] FIG. 3 shows a simulated contour plot of light intensity isolines (lux) using 306 luminaires shown in FIG. 1 to illuminate a target area that is 104 meters long and 68 meters wide;

[0062] FIGS. 4-6 show schematically how a grass field is illuminated by a lighting system according to the invention;

[0063] FIG. 7 shows schematically the same as FIGS. 4-6, but with partly overlapping beams of light; and

[0064] FIG. 8 shows schematically and not to scale a footprint on the ground of one beam of light from one luminaire, and a graph showing the full width half maximum (FWHM) to define the beam angle.

DETAILED DESCRIPTION OF THE DRAWINGS

[0065] In the figures, the reference numeral 1 indicates a luminaire. The luminaire 1 comprises a plurality of LEDs (not shown). The luminaire 1 comprises a frame 13. The luminaire 1 is shown with a fixing iron 15 for fasting the luminaire 1 to a support 2, as seen in FIGS. 4-7. The luminaire 1 comprises a tilting means 17 for adjusting the angle of the frame 13 relative to the fixing iron 15.

[0066] The luminaire 1 is supplied with electricity at a sufficient rate, such as of approximately 2500 W. The LEDs may emit white light with a correlated colour temperature of approximately 4000 K. The luminaire 1 emits light with a narrow beam of light 19. The luminaire 1 may emit light at a beam angle 10 of 5.5° as seen in FIG. 8.

[0067] FIG. 2 shows a simulated contour plot of light intensity isolines. The calculation is based on a soccer field 100 m long and 64 m wide. The luminaires 1 as shown in FIG. 1, are located 32 m above ground, and 506 luminaires 1 are distributed evenly above the field such that the beam of lights 19 are perpendicular to the ground. The simulation shows that the center of the field is illuminated at an intensity above 20,000 lux and a substantial portion of the field is illuminated close to 20,000 lux and above.

[0068] FIG. 3 shows a simulation based on 306 luminaires distributed evenly above a soccer field that is 104 m long and 68 m wide such that the beam of lights 19 are perpendicular to the ground. The simulation shows that the center of the field is illuminated at an intensity above 10,000 lux and a substantial portion of the field is illuminated close to 10,000 lux and above.

[0069] The simulations shown in FIGS. 2 and 3 show that a lighting system 3 according to the invention is able to illuminate grass at a distance to stimulate grass growth.

[0070] FIGS. 4-7 show schematically how the lighting system 3 illuminates a grass field 4. In FIG. 4 a plurality of luminaires 1 are mounted on a support 2, schematically shown as a roof 5 of stadium 6. The plurality of luminaires 1 illuminate the whole grass field 4. In FIGS. 5-6, the plurality of luminaires 1 illuminate ⅓ of the grass field. The plurality of luminaires 1 are tiltable. Thereby, the whole grass field 4 may be illuminated by adjusting successively the angle of the luminaires 1. In FIG. 7 less than ⅓ of the grass field is illuminated. The beam of lights 19 overlap to increase the light intensity at the edge portion of each footprint 7 created by the beam of light 19.

[0071] FIG. 8 shows the footprint 7 on a ground 40 of a beam of light 19 from one luminaire 1. The light is emitted from the luminaires 1 at a beam angle 10 of 5.5° measured from the edge 130 of the frame 13 of the luminaires 1. The footprint 7 is calculated based on that the luminaires 1 is mounted 32 m above the ground 40 and the beam of light 19 is oriented perpendicular to the ground 40. The dimensions are for illustration of the invention only, and the dimensions will change with height above the ground, dimensions of the luminaires 1, beam angle 10, and direction of beam of light relative to the ground 40.

[0072] A schematic curve 8 shows the intensity of light within the beam of light 19. The light intensity is at a maximum M at the centre of the beam of light 19. The light intensity drops at an increasing distance from the centre. The curve shows where light intensity has dropped to half of maximum ½M. As seen in FIG. 8, this defines the full width half maximum FWHM beam angle.

[0073] It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design many alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. Use of the verb “comprise” and its conjugations does not exclude the presence of elements or steps other than those stated in a claim. The article “a” or “an” preceding an element does not exclude the presence of a plurality of such elements.

[0074] The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.